Merge branch 'i2c/for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa...
[muen/linux.git] / drivers / i2c / i2c-core-base.c
1 /*
2  * Linux I2C core
3  *
4  * Copyright (C) 1995-99 Simon G. Vogl
5  *   With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
6  *   Mux support by Rodolfo Giometti <giometti@enneenne.com> and
7  *   Michael Lawnick <michael.lawnick.ext@nsn.com>
8  *
9  * Copyright (C) 2013-2017 Wolfram Sang <wsa@the-dreams.de>
10  *
11  * This program is free software; you can redistribute it and/or modify it
12  * under the terms of the GNU General Public License as published by the Free
13  * Software Foundation; either version 2 of the License, or (at your option)
14  * any later version.
15  *
16  * This program is distributed in the hope that it will be useful, but WITHOUT
17  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
18  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
19  */
20
21 #define pr_fmt(fmt) "i2c-core: " fmt
22
23 #include <dt-bindings/i2c/i2c.h>
24 #include <linux/acpi.h>
25 #include <linux/clk/clk-conf.h>
26 #include <linux/completion.h>
27 #include <linux/delay.h>
28 #include <linux/err.h>
29 #include <linux/errno.h>
30 #include <linux/gpio/consumer.h>
31 #include <linux/i2c.h>
32 #include <linux/i2c-smbus.h>
33 #include <linux/idr.h>
34 #include <linux/init.h>
35 #include <linux/irqflags.h>
36 #include <linux/jump_label.h>
37 #include <linux/kernel.h>
38 #include <linux/module.h>
39 #include <linux/mutex.h>
40 #include <linux/of_device.h>
41 #include <linux/of.h>
42 #include <linux/of_irq.h>
43 #include <linux/pm_domain.h>
44 #include <linux/pm_runtime.h>
45 #include <linux/pm_wakeirq.h>
46 #include <linux/property.h>
47 #include <linux/rwsem.h>
48 #include <linux/slab.h>
49
50 #include "i2c-core.h"
51
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/i2c.h>
54
55 #define I2C_ADDR_OFFSET_TEN_BIT 0xa000
56 #define I2C_ADDR_OFFSET_SLAVE   0x1000
57
58 #define I2C_ADDR_7BITS_MAX      0x77
59 #define I2C_ADDR_7BITS_COUNT    (I2C_ADDR_7BITS_MAX + 1)
60
61 #define I2C_ADDR_DEVICE_ID      0x7c
62
63 /*
64  * core_lock protects i2c_adapter_idr, and guarantees that device detection,
65  * deletion of detected devices, and attach_adapter calls are serialized
66  */
67 static DEFINE_MUTEX(core_lock);
68 static DEFINE_IDR(i2c_adapter_idr);
69
70 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
71
72 static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
73 static bool is_registered;
74
75 int i2c_transfer_trace_reg(void)
76 {
77         static_branch_inc(&i2c_trace_msg_key);
78         return 0;
79 }
80
81 void i2c_transfer_trace_unreg(void)
82 {
83         static_branch_dec(&i2c_trace_msg_key);
84 }
85
86 const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
87                                                 const struct i2c_client *client)
88 {
89         if (!(id && client))
90                 return NULL;
91
92         while (id->name[0]) {
93                 if (strcmp(client->name, id->name) == 0)
94                         return id;
95                 id++;
96         }
97         return NULL;
98 }
99 EXPORT_SYMBOL_GPL(i2c_match_id);
100
101 static int i2c_device_match(struct device *dev, struct device_driver *drv)
102 {
103         struct i2c_client       *client = i2c_verify_client(dev);
104         struct i2c_driver       *driver;
105
106
107         /* Attempt an OF style match */
108         if (i2c_of_match_device(drv->of_match_table, client))
109                 return 1;
110
111         /* Then ACPI style match */
112         if (acpi_driver_match_device(dev, drv))
113                 return 1;
114
115         driver = to_i2c_driver(drv);
116
117         /* Finally an I2C match */
118         if (i2c_match_id(driver->id_table, client))
119                 return 1;
120
121         return 0;
122 }
123
124 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
125 {
126         struct i2c_client *client = to_i2c_client(dev);
127         int rc;
128
129         rc = of_device_uevent_modalias(dev, env);
130         if (rc != -ENODEV)
131                 return rc;
132
133         rc = acpi_device_uevent_modalias(dev, env);
134         if (rc != -ENODEV)
135                 return rc;
136
137         return add_uevent_var(env, "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name);
138 }
139
140 /* i2c bus recovery routines */
141 static int get_scl_gpio_value(struct i2c_adapter *adap)
142 {
143         return gpiod_get_value_cansleep(adap->bus_recovery_info->scl_gpiod);
144 }
145
146 static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
147 {
148         gpiod_set_value_cansleep(adap->bus_recovery_info->scl_gpiod, val);
149 }
150
151 static int get_sda_gpio_value(struct i2c_adapter *adap)
152 {
153         return gpiod_get_value_cansleep(adap->bus_recovery_info->sda_gpiod);
154 }
155
156 static void set_sda_gpio_value(struct i2c_adapter *adap, int val)
157 {
158         gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val);
159 }
160
161 static int i2c_generic_bus_free(struct i2c_adapter *adap)
162 {
163         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
164         int ret = -EOPNOTSUPP;
165
166         if (bri->get_bus_free)
167                 ret = bri->get_bus_free(adap);
168         else if (bri->get_sda)
169                 ret = bri->get_sda(adap);
170
171         if (ret < 0)
172                 return ret;
173
174         return ret ? 0 : -EBUSY;
175 }
176
177 /*
178  * We are generating clock pulses. ndelay() determines durating of clk pulses.
179  * We will generate clock with rate 100 KHz and so duration of both clock levels
180  * is: delay in ns = (10^6 / 100) / 2
181  */
182 #define RECOVERY_NDELAY         5000
183 #define RECOVERY_CLK_CNT        9
184
185 int i2c_generic_scl_recovery(struct i2c_adapter *adap)
186 {
187         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
188         int i = 0, scl = 1, ret;
189
190         if (bri->prepare_recovery)
191                 bri->prepare_recovery(adap);
192
193         /*
194          * If we can set SDA, we will always create a STOP to ensure additional
195          * pulses will do no harm. This is achieved by letting SDA follow SCL
196          * half a cycle later. Check the 'incomplete_write_byte' fault injector
197          * for details.
198          */
199         bri->set_scl(adap, scl);
200         ndelay(RECOVERY_NDELAY / 2);
201         if (bri->set_sda)
202                 bri->set_sda(adap, scl);
203         ndelay(RECOVERY_NDELAY / 2);
204
205         /*
206          * By this time SCL is high, as we need to give 9 falling-rising edges
207          */
208         while (i++ < RECOVERY_CLK_CNT * 2) {
209                 if (scl) {
210                         /* SCL shouldn't be low here */
211                         if (!bri->get_scl(adap)) {
212                                 dev_err(&adap->dev,
213                                         "SCL is stuck low, exit recovery\n");
214                                 ret = -EBUSY;
215                                 break;
216                         }
217                 }
218
219                 scl = !scl;
220                 bri->set_scl(adap, scl);
221                 /* Creating STOP again, see above */
222                 ndelay(RECOVERY_NDELAY / 2);
223                 if (bri->set_sda)
224                         bri->set_sda(adap, scl);
225                 ndelay(RECOVERY_NDELAY / 2);
226
227                 if (scl) {
228                         ret = i2c_generic_bus_free(adap);
229                         if (ret == 0)
230                                 break;
231                 }
232         }
233
234         /* If we can't check bus status, assume recovery worked */
235         if (ret == -EOPNOTSUPP)
236                 ret = 0;
237
238         if (bri->unprepare_recovery)
239                 bri->unprepare_recovery(adap);
240
241         return ret;
242 }
243 EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
244
245 int i2c_recover_bus(struct i2c_adapter *adap)
246 {
247         if (!adap->bus_recovery_info)
248                 return -EOPNOTSUPP;
249
250         dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
251         return adap->bus_recovery_info->recover_bus(adap);
252 }
253 EXPORT_SYMBOL_GPL(i2c_recover_bus);
254
255 static void i2c_init_recovery(struct i2c_adapter *adap)
256 {
257         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
258         char *err_str;
259
260         if (!bri)
261                 return;
262
263         if (!bri->recover_bus) {
264                 err_str = "no recover_bus() found";
265                 goto err;
266         }
267
268         if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) {
269                 bri->get_scl = get_scl_gpio_value;
270                 bri->set_scl = set_scl_gpio_value;
271                 if (bri->sda_gpiod) {
272                         bri->get_sda = get_sda_gpio_value;
273                         /* FIXME: add proper flag instead of '0' once available */
274                         if (gpiod_get_direction(bri->sda_gpiod) == 0)
275                                 bri->set_sda = set_sda_gpio_value;
276                 }
277                 return;
278         }
279
280         if (bri->recover_bus == i2c_generic_scl_recovery) {
281                 /* Generic SCL recovery */
282                 if (!bri->set_scl || !bri->get_scl) {
283                         err_str = "no {get|set}_scl() found";
284                         goto err;
285                 }
286                 if (!bri->set_sda && !bri->get_sda) {
287                         err_str = "either get_sda() or set_sda() needed";
288                         goto err;
289                 }
290         }
291
292         return;
293  err:
294         dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
295         adap->bus_recovery_info = NULL;
296 }
297
298 static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
299 {
300         struct i2c_adapter *adap = client->adapter;
301         unsigned int irq;
302
303         if (!adap->host_notify_domain)
304                 return -ENXIO;
305
306         if (client->flags & I2C_CLIENT_TEN)
307                 return -EINVAL;
308
309         irq = irq_find_mapping(adap->host_notify_domain, client->addr);
310         if (!irq)
311                 irq = irq_create_mapping(adap->host_notify_domain,
312                                          client->addr);
313
314         return irq > 0 ? irq : -ENXIO;
315 }
316
317 static int i2c_device_probe(struct device *dev)
318 {
319         struct i2c_client       *client = i2c_verify_client(dev);
320         struct i2c_driver       *driver;
321         int status;
322
323         if (!client)
324                 return 0;
325
326         driver = to_i2c_driver(dev->driver);
327
328         if (!client->irq && !driver->disable_i2c_core_irq_mapping) {
329                 int irq = -ENOENT;
330
331                 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
332                         dev_dbg(dev, "Using Host Notify IRQ\n");
333                         irq = i2c_smbus_host_notify_to_irq(client);
334                 } else if (dev->of_node) {
335                         irq = of_irq_get_byname(dev->of_node, "irq");
336                         if (irq == -EINVAL || irq == -ENODATA)
337                                 irq = of_irq_get(dev->of_node, 0);
338                 } else if (ACPI_COMPANION(dev)) {
339                         irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
340                 }
341                 if (irq == -EPROBE_DEFER)
342                         return irq;
343
344                 if (irq < 0)
345                         irq = 0;
346
347                 client->irq = irq;
348         }
349
350         /*
351          * An I2C ID table is not mandatory, if and only if, a suitable OF
352          * or ACPI ID table is supplied for the probing device.
353          */
354         if (!driver->id_table &&
355             !i2c_acpi_match_device(dev->driver->acpi_match_table, client) &&
356             !i2c_of_match_device(dev->driver->of_match_table, client))
357                 return -ENODEV;
358
359         if (client->flags & I2C_CLIENT_WAKE) {
360                 int wakeirq = -ENOENT;
361
362                 if (dev->of_node) {
363                         wakeirq = of_irq_get_byname(dev->of_node, "wakeup");
364                         if (wakeirq == -EPROBE_DEFER)
365                                 return wakeirq;
366                 }
367
368                 device_init_wakeup(&client->dev, true);
369
370                 if (wakeirq > 0 && wakeirq != client->irq)
371                         status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
372                 else if (client->irq > 0)
373                         status = dev_pm_set_wake_irq(dev, client->irq);
374                 else
375                         status = 0;
376
377                 if (status)
378                         dev_warn(&client->dev, "failed to set up wakeup irq\n");
379         }
380
381         dev_dbg(dev, "probe\n");
382
383         status = of_clk_set_defaults(dev->of_node, false);
384         if (status < 0)
385                 goto err_clear_wakeup_irq;
386
387         status = dev_pm_domain_attach(&client->dev, true);
388         if (status)
389                 goto err_clear_wakeup_irq;
390
391         /*
392          * When there are no more users of probe(),
393          * rename probe_new to probe.
394          */
395         if (driver->probe_new)
396                 status = driver->probe_new(client);
397         else if (driver->probe)
398                 status = driver->probe(client,
399                                        i2c_match_id(driver->id_table, client));
400         else
401                 status = -EINVAL;
402
403         if (status)
404                 goto err_detach_pm_domain;
405
406         return 0;
407
408 err_detach_pm_domain:
409         dev_pm_domain_detach(&client->dev, true);
410 err_clear_wakeup_irq:
411         dev_pm_clear_wake_irq(&client->dev);
412         device_init_wakeup(&client->dev, false);
413         return status;
414 }
415
416 static int i2c_device_remove(struct device *dev)
417 {
418         struct i2c_client       *client = i2c_verify_client(dev);
419         struct i2c_driver       *driver;
420         int status = 0;
421
422         if (!client || !dev->driver)
423                 return 0;
424
425         driver = to_i2c_driver(dev->driver);
426         if (driver->remove) {
427                 dev_dbg(dev, "remove\n");
428                 status = driver->remove(client);
429         }
430
431         dev_pm_domain_detach(&client->dev, true);
432
433         dev_pm_clear_wake_irq(&client->dev);
434         device_init_wakeup(&client->dev, false);
435
436         return status;
437 }
438
439 static void i2c_device_shutdown(struct device *dev)
440 {
441         struct i2c_client *client = i2c_verify_client(dev);
442         struct i2c_driver *driver;
443
444         if (!client || !dev->driver)
445                 return;
446         driver = to_i2c_driver(dev->driver);
447         if (driver->shutdown)
448                 driver->shutdown(client);
449 }
450
451 static void i2c_client_dev_release(struct device *dev)
452 {
453         kfree(to_i2c_client(dev));
454 }
455
456 static ssize_t
457 show_name(struct device *dev, struct device_attribute *attr, char *buf)
458 {
459         return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
460                        to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
461 }
462 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
463
464 static ssize_t
465 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
466 {
467         struct i2c_client *client = to_i2c_client(dev);
468         int len;
469
470         len = of_device_modalias(dev, buf, PAGE_SIZE);
471         if (len != -ENODEV)
472                 return len;
473
474         len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
475         if (len != -ENODEV)
476                 return len;
477
478         return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
479 }
480 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
481
482 static struct attribute *i2c_dev_attrs[] = {
483         &dev_attr_name.attr,
484         /* modalias helps coldplug:  modprobe $(cat .../modalias) */
485         &dev_attr_modalias.attr,
486         NULL
487 };
488 ATTRIBUTE_GROUPS(i2c_dev);
489
490 struct bus_type i2c_bus_type = {
491         .name           = "i2c",
492         .match          = i2c_device_match,
493         .probe          = i2c_device_probe,
494         .remove         = i2c_device_remove,
495         .shutdown       = i2c_device_shutdown,
496 };
497 EXPORT_SYMBOL_GPL(i2c_bus_type);
498
499 struct device_type i2c_client_type = {
500         .groups         = i2c_dev_groups,
501         .uevent         = i2c_device_uevent,
502         .release        = i2c_client_dev_release,
503 };
504 EXPORT_SYMBOL_GPL(i2c_client_type);
505
506
507 /**
508  * i2c_verify_client - return parameter as i2c_client, or NULL
509  * @dev: device, probably from some driver model iterator
510  *
511  * When traversing the driver model tree, perhaps using driver model
512  * iterators like @device_for_each_child(), you can't assume very much
513  * about the nodes you find.  Use this function to avoid oopses caused
514  * by wrongly treating some non-I2C device as an i2c_client.
515  */
516 struct i2c_client *i2c_verify_client(struct device *dev)
517 {
518         return (dev->type == &i2c_client_type)
519                         ? to_i2c_client(dev)
520                         : NULL;
521 }
522 EXPORT_SYMBOL(i2c_verify_client);
523
524
525 /* Return a unique address which takes the flags of the client into account */
526 static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
527 {
528         unsigned short addr = client->addr;
529
530         /* For some client flags, add an arbitrary offset to avoid collisions */
531         if (client->flags & I2C_CLIENT_TEN)
532                 addr |= I2C_ADDR_OFFSET_TEN_BIT;
533
534         if (client->flags & I2C_CLIENT_SLAVE)
535                 addr |= I2C_ADDR_OFFSET_SLAVE;
536
537         return addr;
538 }
539
540 /* This is a permissive address validity check, I2C address map constraints
541  * are purposely not enforced, except for the general call address. */
542 static int i2c_check_addr_validity(unsigned int addr, unsigned short flags)
543 {
544         if (flags & I2C_CLIENT_TEN) {
545                 /* 10-bit address, all values are valid */
546                 if (addr > 0x3ff)
547                         return -EINVAL;
548         } else {
549                 /* 7-bit address, reject the general call address */
550                 if (addr == 0x00 || addr > 0x7f)
551                         return -EINVAL;
552         }
553         return 0;
554 }
555
556 /* And this is a strict address validity check, used when probing. If a
557  * device uses a reserved address, then it shouldn't be probed. 7-bit
558  * addressing is assumed, 10-bit address devices are rare and should be
559  * explicitly enumerated. */
560 int i2c_check_7bit_addr_validity_strict(unsigned short addr)
561 {
562         /*
563          * Reserved addresses per I2C specification:
564          *  0x00       General call address / START byte
565          *  0x01       CBUS address
566          *  0x02       Reserved for different bus format
567          *  0x03       Reserved for future purposes
568          *  0x04-0x07  Hs-mode master code
569          *  0x78-0x7b  10-bit slave addressing
570          *  0x7c-0x7f  Reserved for future purposes
571          */
572         if (addr < 0x08 || addr > 0x77)
573                 return -EINVAL;
574         return 0;
575 }
576
577 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
578 {
579         struct i2c_client       *client = i2c_verify_client(dev);
580         int                     addr = *(int *)addrp;
581
582         if (client && i2c_encode_flags_to_addr(client) == addr)
583                 return -EBUSY;
584         return 0;
585 }
586
587 /* walk up mux tree */
588 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
589 {
590         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
591         int result;
592
593         result = device_for_each_child(&adapter->dev, &addr,
594                                         __i2c_check_addr_busy);
595
596         if (!result && parent)
597                 result = i2c_check_mux_parents(parent, addr);
598
599         return result;
600 }
601
602 /* recurse down mux tree */
603 static int i2c_check_mux_children(struct device *dev, void *addrp)
604 {
605         int result;
606
607         if (dev->type == &i2c_adapter_type)
608                 result = device_for_each_child(dev, addrp,
609                                                 i2c_check_mux_children);
610         else
611                 result = __i2c_check_addr_busy(dev, addrp);
612
613         return result;
614 }
615
616 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
617 {
618         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
619         int result = 0;
620
621         if (parent)
622                 result = i2c_check_mux_parents(parent, addr);
623
624         if (!result)
625                 result = device_for_each_child(&adapter->dev, &addr,
626                                                 i2c_check_mux_children);
627
628         return result;
629 }
630
631 /**
632  * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
633  * @adapter: Target I2C bus segment
634  * @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
635  *      locks only this branch in the adapter tree
636  */
637 static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
638                                  unsigned int flags)
639 {
640         rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter));
641 }
642
643 /**
644  * i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
645  * @adapter: Target I2C bus segment
646  * @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
647  *      trylocks only this branch in the adapter tree
648  */
649 static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
650                                    unsigned int flags)
651 {
652         return rt_mutex_trylock(&adapter->bus_lock);
653 }
654
655 /**
656  * i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
657  * @adapter: Target I2C bus segment
658  * @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
659  *      unlocks only this branch in the adapter tree
660  */
661 static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
662                                    unsigned int flags)
663 {
664         rt_mutex_unlock(&adapter->bus_lock);
665 }
666
667 static void i2c_dev_set_name(struct i2c_adapter *adap,
668                              struct i2c_client *client,
669                              struct i2c_board_info const *info)
670 {
671         struct acpi_device *adev = ACPI_COMPANION(&client->dev);
672
673         if (info && info->dev_name) {
674                 dev_set_name(&client->dev, "i2c-%s", info->dev_name);
675                 return;
676         }
677
678         if (adev) {
679                 dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
680                 return;
681         }
682
683         dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
684                      i2c_encode_flags_to_addr(client));
685 }
686
687 static int i2c_dev_irq_from_resources(const struct resource *resources,
688                                       unsigned int num_resources)
689 {
690         struct irq_data *irqd;
691         int i;
692
693         for (i = 0; i < num_resources; i++) {
694                 const struct resource *r = &resources[i];
695
696                 if (resource_type(r) != IORESOURCE_IRQ)
697                         continue;
698
699                 if (r->flags & IORESOURCE_BITS) {
700                         irqd = irq_get_irq_data(r->start);
701                         if (!irqd)
702                                 break;
703
704                         irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
705                 }
706
707                 return r->start;
708         }
709
710         return 0;
711 }
712
713 /**
714  * i2c_new_device - instantiate an i2c device
715  * @adap: the adapter managing the device
716  * @info: describes one I2C device; bus_num is ignored
717  * Context: can sleep
718  *
719  * Create an i2c device. Binding is handled through driver model
720  * probe()/remove() methods.  A driver may be bound to this device when we
721  * return from this function, or any later moment (e.g. maybe hotplugging will
722  * load the driver module).  This call is not appropriate for use by mainboard
723  * initialization logic, which usually runs during an arch_initcall() long
724  * before any i2c_adapter could exist.
725  *
726  * This returns the new i2c client, which may be saved for later use with
727  * i2c_unregister_device(); or NULL to indicate an error.
728  */
729 struct i2c_client *
730 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
731 {
732         struct i2c_client       *client;
733         int                     status;
734
735         client = kzalloc(sizeof *client, GFP_KERNEL);
736         if (!client)
737                 return NULL;
738
739         client->adapter = adap;
740
741         client->dev.platform_data = info->platform_data;
742         client->flags = info->flags;
743         client->addr = info->addr;
744
745         client->irq = info->irq;
746         if (!client->irq)
747                 client->irq = i2c_dev_irq_from_resources(info->resources,
748                                                          info->num_resources);
749
750         strlcpy(client->name, info->type, sizeof(client->name));
751
752         status = i2c_check_addr_validity(client->addr, client->flags);
753         if (status) {
754                 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
755                         client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
756                 goto out_err_silent;
757         }
758
759         /* Check for address business */
760         status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
761         if (status)
762                 goto out_err;
763
764         client->dev.parent = &client->adapter->dev;
765         client->dev.bus = &i2c_bus_type;
766         client->dev.type = &i2c_client_type;
767         client->dev.of_node = of_node_get(info->of_node);
768         client->dev.fwnode = info->fwnode;
769
770         i2c_dev_set_name(adap, client, info);
771
772         if (info->properties) {
773                 status = device_add_properties(&client->dev, info->properties);
774                 if (status) {
775                         dev_err(&adap->dev,
776                                 "Failed to add properties to client %s: %d\n",
777                                 client->name, status);
778                         goto out_err_put_of_node;
779                 }
780         }
781
782         status = device_register(&client->dev);
783         if (status)
784                 goto out_free_props;
785
786         dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
787                 client->name, dev_name(&client->dev));
788
789         return client;
790
791 out_free_props:
792         if (info->properties)
793                 device_remove_properties(&client->dev);
794 out_err_put_of_node:
795         of_node_put(info->of_node);
796 out_err:
797         dev_err(&adap->dev,
798                 "Failed to register i2c client %s at 0x%02x (%d)\n",
799                 client->name, client->addr, status);
800 out_err_silent:
801         kfree(client);
802         return NULL;
803 }
804 EXPORT_SYMBOL_GPL(i2c_new_device);
805
806
807 /**
808  * i2c_unregister_device - reverse effect of i2c_new_device()
809  * @client: value returned from i2c_new_device()
810  * Context: can sleep
811  */
812 void i2c_unregister_device(struct i2c_client *client)
813 {
814         if (!client)
815                 return;
816
817         if (client->dev.of_node) {
818                 of_node_clear_flag(client->dev.of_node, OF_POPULATED);
819                 of_node_put(client->dev.of_node);
820         }
821
822         if (ACPI_COMPANION(&client->dev))
823                 acpi_device_clear_enumerated(ACPI_COMPANION(&client->dev));
824         device_unregister(&client->dev);
825 }
826 EXPORT_SYMBOL_GPL(i2c_unregister_device);
827
828
829 static const struct i2c_device_id dummy_id[] = {
830         { "dummy", 0 },
831         { },
832 };
833
834 static int dummy_probe(struct i2c_client *client,
835                        const struct i2c_device_id *id)
836 {
837         return 0;
838 }
839
840 static int dummy_remove(struct i2c_client *client)
841 {
842         return 0;
843 }
844
845 static struct i2c_driver dummy_driver = {
846         .driver.name    = "dummy",
847         .probe          = dummy_probe,
848         .remove         = dummy_remove,
849         .id_table       = dummy_id,
850 };
851
852 /**
853  * i2c_new_dummy - return a new i2c device bound to a dummy driver
854  * @adapter: the adapter managing the device
855  * @address: seven bit address to be used
856  * Context: can sleep
857  *
858  * This returns an I2C client bound to the "dummy" driver, intended for use
859  * with devices that consume multiple addresses.  Examples of such chips
860  * include various EEPROMS (like 24c04 and 24c08 models).
861  *
862  * These dummy devices have two main uses.  First, most I2C and SMBus calls
863  * except i2c_transfer() need a client handle; the dummy will be that handle.
864  * And second, this prevents the specified address from being bound to a
865  * different driver.
866  *
867  * This returns the new i2c client, which should be saved for later use with
868  * i2c_unregister_device(); or NULL to indicate an error.
869  */
870 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
871 {
872         struct i2c_board_info info = {
873                 I2C_BOARD_INFO("dummy", address),
874         };
875
876         return i2c_new_device(adapter, &info);
877 }
878 EXPORT_SYMBOL_GPL(i2c_new_dummy);
879
880 /**
881  * i2c_new_secondary_device - Helper to get the instantiated secondary address
882  * and create the associated device
883  * @client: Handle to the primary client
884  * @name: Handle to specify which secondary address to get
885  * @default_addr: Used as a fallback if no secondary address was specified
886  * Context: can sleep
887  *
888  * I2C clients can be composed of multiple I2C slaves bound together in a single
889  * component. The I2C client driver then binds to the master I2C slave and needs
890  * to create I2C dummy clients to communicate with all the other slaves.
891  *
892  * This function creates and returns an I2C dummy client whose I2C address is
893  * retrieved from the platform firmware based on the given slave name. If no
894  * address is specified by the firmware default_addr is used.
895  *
896  * On DT-based platforms the address is retrieved from the "reg" property entry
897  * cell whose "reg-names" value matches the slave name.
898  *
899  * This returns the new i2c client, which should be saved for later use with
900  * i2c_unregister_device(); or NULL to indicate an error.
901  */
902 struct i2c_client *i2c_new_secondary_device(struct i2c_client *client,
903                                                 const char *name,
904                                                 u16 default_addr)
905 {
906         struct device_node *np = client->dev.of_node;
907         u32 addr = default_addr;
908         int i;
909
910         if (np) {
911                 i = of_property_match_string(np, "reg-names", name);
912                 if (i >= 0)
913                         of_property_read_u32_index(np, "reg", i, &addr);
914         }
915
916         dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
917         return i2c_new_dummy(client->adapter, addr);
918 }
919 EXPORT_SYMBOL_GPL(i2c_new_secondary_device);
920
921 /* ------------------------------------------------------------------------- */
922
923 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
924
925 static void i2c_adapter_dev_release(struct device *dev)
926 {
927         struct i2c_adapter *adap = to_i2c_adapter(dev);
928         complete(&adap->dev_released);
929 }
930
931 unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
932 {
933         unsigned int depth = 0;
934
935         while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
936                 depth++;
937
938         WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
939                   "adapter depth exceeds lockdep subclass limit\n");
940
941         return depth;
942 }
943 EXPORT_SYMBOL_GPL(i2c_adapter_depth);
944
945 /*
946  * Let users instantiate I2C devices through sysfs. This can be used when
947  * platform initialization code doesn't contain the proper data for
948  * whatever reason. Also useful for drivers that do device detection and
949  * detection fails, either because the device uses an unexpected address,
950  * or this is a compatible device with different ID register values.
951  *
952  * Parameter checking may look overzealous, but we really don't want
953  * the user to provide incorrect parameters.
954  */
955 static ssize_t
956 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
957                      const char *buf, size_t count)
958 {
959         struct i2c_adapter *adap = to_i2c_adapter(dev);
960         struct i2c_board_info info;
961         struct i2c_client *client;
962         char *blank, end;
963         int res;
964
965         memset(&info, 0, sizeof(struct i2c_board_info));
966
967         blank = strchr(buf, ' ');
968         if (!blank) {
969                 dev_err(dev, "%s: Missing parameters\n", "new_device");
970                 return -EINVAL;
971         }
972         if (blank - buf > I2C_NAME_SIZE - 1) {
973                 dev_err(dev, "%s: Invalid device name\n", "new_device");
974                 return -EINVAL;
975         }
976         memcpy(info.type, buf, blank - buf);
977
978         /* Parse remaining parameters, reject extra parameters */
979         res = sscanf(++blank, "%hi%c", &info.addr, &end);
980         if (res < 1) {
981                 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
982                 return -EINVAL;
983         }
984         if (res > 1  && end != '\n') {
985                 dev_err(dev, "%s: Extra parameters\n", "new_device");
986                 return -EINVAL;
987         }
988
989         if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
990                 info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
991                 info.flags |= I2C_CLIENT_TEN;
992         }
993
994         if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
995                 info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
996                 info.flags |= I2C_CLIENT_SLAVE;
997         }
998
999         client = i2c_new_device(adap, &info);
1000         if (!client)
1001                 return -EINVAL;
1002
1003         /* Keep track of the added device */
1004         mutex_lock(&adap->userspace_clients_lock);
1005         list_add_tail(&client->detected, &adap->userspace_clients);
1006         mutex_unlock(&adap->userspace_clients_lock);
1007         dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
1008                  info.type, info.addr);
1009
1010         return count;
1011 }
1012 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
1013
1014 /*
1015  * And of course let the users delete the devices they instantiated, if
1016  * they got it wrong. This interface can only be used to delete devices
1017  * instantiated by i2c_sysfs_new_device above. This guarantees that we
1018  * don't delete devices to which some kernel code still has references.
1019  *
1020  * Parameter checking may look overzealous, but we really don't want
1021  * the user to delete the wrong device.
1022  */
1023 static ssize_t
1024 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
1025                         const char *buf, size_t count)
1026 {
1027         struct i2c_adapter *adap = to_i2c_adapter(dev);
1028         struct i2c_client *client, *next;
1029         unsigned short addr;
1030         char end;
1031         int res;
1032
1033         /* Parse parameters, reject extra parameters */
1034         res = sscanf(buf, "%hi%c", &addr, &end);
1035         if (res < 1) {
1036                 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1037                 return -EINVAL;
1038         }
1039         if (res > 1  && end != '\n') {
1040                 dev_err(dev, "%s: Extra parameters\n", "delete_device");
1041                 return -EINVAL;
1042         }
1043
1044         /* Make sure the device was added through sysfs */
1045         res = -ENOENT;
1046         mutex_lock_nested(&adap->userspace_clients_lock,
1047                           i2c_adapter_depth(adap));
1048         list_for_each_entry_safe(client, next, &adap->userspace_clients,
1049                                  detected) {
1050                 if (i2c_encode_flags_to_addr(client) == addr) {
1051                         dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1052                                  "delete_device", client->name, client->addr);
1053
1054                         list_del(&client->detected);
1055                         i2c_unregister_device(client);
1056                         res = count;
1057                         break;
1058                 }
1059         }
1060         mutex_unlock(&adap->userspace_clients_lock);
1061
1062         if (res < 0)
1063                 dev_err(dev, "%s: Can't find device in list\n",
1064                         "delete_device");
1065         return res;
1066 }
1067 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1068                                    i2c_sysfs_delete_device);
1069
1070 static struct attribute *i2c_adapter_attrs[] = {
1071         &dev_attr_name.attr,
1072         &dev_attr_new_device.attr,
1073         &dev_attr_delete_device.attr,
1074         NULL
1075 };
1076 ATTRIBUTE_GROUPS(i2c_adapter);
1077
1078 struct device_type i2c_adapter_type = {
1079         .groups         = i2c_adapter_groups,
1080         .release        = i2c_adapter_dev_release,
1081 };
1082 EXPORT_SYMBOL_GPL(i2c_adapter_type);
1083
1084 /**
1085  * i2c_verify_adapter - return parameter as i2c_adapter or NULL
1086  * @dev: device, probably from some driver model iterator
1087  *
1088  * When traversing the driver model tree, perhaps using driver model
1089  * iterators like @device_for_each_child(), you can't assume very much
1090  * about the nodes you find.  Use this function to avoid oopses caused
1091  * by wrongly treating some non-I2C device as an i2c_adapter.
1092  */
1093 struct i2c_adapter *i2c_verify_adapter(struct device *dev)
1094 {
1095         return (dev->type == &i2c_adapter_type)
1096                         ? to_i2c_adapter(dev)
1097                         : NULL;
1098 }
1099 EXPORT_SYMBOL(i2c_verify_adapter);
1100
1101 #ifdef CONFIG_I2C_COMPAT
1102 static struct class_compat *i2c_adapter_compat_class;
1103 #endif
1104
1105 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1106 {
1107         struct i2c_devinfo      *devinfo;
1108
1109         down_read(&__i2c_board_lock);
1110         list_for_each_entry(devinfo, &__i2c_board_list, list) {
1111                 if (devinfo->busnum == adapter->nr
1112                                 && !i2c_new_device(adapter,
1113                                                 &devinfo->board_info))
1114                         dev_err(&adapter->dev,
1115                                 "Can't create device at 0x%02x\n",
1116                                 devinfo->board_info.addr);
1117         }
1118         up_read(&__i2c_board_lock);
1119 }
1120
1121 static int i2c_do_add_adapter(struct i2c_driver *driver,
1122                               struct i2c_adapter *adap)
1123 {
1124         /* Detect supported devices on that bus, and instantiate them */
1125         i2c_detect(adap, driver);
1126
1127         /* Let legacy drivers scan this bus for matching devices */
1128         if (driver->attach_adapter) {
1129                 dev_warn(&adap->dev, "%s: attach_adapter method is deprecated\n",
1130                          driver->driver.name);
1131                 dev_warn(&adap->dev,
1132                          "Please use another way to instantiate your i2c_client\n");
1133                 /* We ignore the return code; if it fails, too bad */
1134                 driver->attach_adapter(adap);
1135         }
1136         return 0;
1137 }
1138
1139 static int __process_new_adapter(struct device_driver *d, void *data)
1140 {
1141         return i2c_do_add_adapter(to_i2c_driver(d), data);
1142 }
1143
1144 static const struct i2c_lock_operations i2c_adapter_lock_ops = {
1145         .lock_bus =    i2c_adapter_lock_bus,
1146         .trylock_bus = i2c_adapter_trylock_bus,
1147         .unlock_bus =  i2c_adapter_unlock_bus,
1148 };
1149
1150 static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
1151 {
1152         struct irq_domain *domain = adap->host_notify_domain;
1153         irq_hw_number_t hwirq;
1154
1155         if (!domain)
1156                 return;
1157
1158         for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
1159                 irq_dispose_mapping(irq_find_mapping(domain, hwirq));
1160
1161         irq_domain_remove(domain);
1162         adap->host_notify_domain = NULL;
1163 }
1164
1165 static int i2c_host_notify_irq_map(struct irq_domain *h,
1166                                           unsigned int virq,
1167                                           irq_hw_number_t hw_irq_num)
1168 {
1169         irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
1170
1171         return 0;
1172 }
1173
1174 static const struct irq_domain_ops i2c_host_notify_irq_ops = {
1175         .map = i2c_host_notify_irq_map,
1176 };
1177
1178 static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
1179 {
1180         struct irq_domain *domain;
1181
1182         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
1183                 return 0;
1184
1185         domain = irq_domain_create_linear(adap->dev.fwnode,
1186                                           I2C_ADDR_7BITS_COUNT,
1187                                           &i2c_host_notify_irq_ops, adap);
1188         if (!domain)
1189                 return -ENOMEM;
1190
1191         adap->host_notify_domain = domain;
1192
1193         return 0;
1194 }
1195
1196 /**
1197  * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
1198  * I2C client.
1199  * @adap: the adapter
1200  * @addr: the I2C address of the notifying device
1201  * Context: can't sleep
1202  *
1203  * Helper function to be called from an I2C bus driver's interrupt
1204  * handler. It will schedule the Host Notify IRQ.
1205  */
1206 int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
1207 {
1208         int irq;
1209
1210         if (!adap)
1211                 return -EINVAL;
1212
1213         irq = irq_find_mapping(adap->host_notify_domain, addr);
1214         if (irq <= 0)
1215                 return -ENXIO;
1216
1217         generic_handle_irq(irq);
1218
1219         return 0;
1220 }
1221 EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
1222
1223 static int i2c_register_adapter(struct i2c_adapter *adap)
1224 {
1225         int res = -EINVAL;
1226
1227         /* Can't register until after driver model init */
1228         if (WARN_ON(!is_registered)) {
1229                 res = -EAGAIN;
1230                 goto out_list;
1231         }
1232
1233         /* Sanity checks */
1234         if (WARN(!adap->name[0], "i2c adapter has no name"))
1235                 goto out_list;
1236
1237         if (!adap->algo) {
1238                 pr_err("adapter '%s': no algo supplied!\n", adap->name);
1239                 goto out_list;
1240         }
1241
1242         if (!adap->lock_ops)
1243                 adap->lock_ops = &i2c_adapter_lock_ops;
1244
1245         rt_mutex_init(&adap->bus_lock);
1246         rt_mutex_init(&adap->mux_lock);
1247         mutex_init(&adap->userspace_clients_lock);
1248         INIT_LIST_HEAD(&adap->userspace_clients);
1249
1250         /* Set default timeout to 1 second if not already set */
1251         if (adap->timeout == 0)
1252                 adap->timeout = HZ;
1253
1254         /* register soft irqs for Host Notify */
1255         res = i2c_setup_host_notify_irq_domain(adap);
1256         if (res) {
1257                 pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
1258                        adap->name, res);
1259                 goto out_list;
1260         }
1261
1262         dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1263         adap->dev.bus = &i2c_bus_type;
1264         adap->dev.type = &i2c_adapter_type;
1265         res = device_register(&adap->dev);
1266         if (res) {
1267                 pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
1268                 goto out_list;
1269         }
1270
1271         res = of_i2c_setup_smbus_alert(adap);
1272         if (res)
1273                 goto out_reg;
1274
1275         dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1276
1277         pm_runtime_no_callbacks(&adap->dev);
1278         pm_suspend_ignore_children(&adap->dev, true);
1279         pm_runtime_enable(&adap->dev);
1280
1281 #ifdef CONFIG_I2C_COMPAT
1282         res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
1283                                        adap->dev.parent);
1284         if (res)
1285                 dev_warn(&adap->dev,
1286                          "Failed to create compatibility class link\n");
1287 #endif
1288
1289         i2c_init_recovery(adap);
1290
1291         /* create pre-declared device nodes */
1292         of_i2c_register_devices(adap);
1293         i2c_acpi_register_devices(adap);
1294         i2c_acpi_install_space_handler(adap);
1295
1296         if (adap->nr < __i2c_first_dynamic_bus_num)
1297                 i2c_scan_static_board_info(adap);
1298
1299         /* Notify drivers */
1300         mutex_lock(&core_lock);
1301         bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1302         mutex_unlock(&core_lock);
1303
1304         return 0;
1305
1306 out_reg:
1307         init_completion(&adap->dev_released);
1308         device_unregister(&adap->dev);
1309         wait_for_completion(&adap->dev_released);
1310 out_list:
1311         mutex_lock(&core_lock);
1312         idr_remove(&i2c_adapter_idr, adap->nr);
1313         mutex_unlock(&core_lock);
1314         return res;
1315 }
1316
1317 /**
1318  * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1319  * @adap: the adapter to register (with adap->nr initialized)
1320  * Context: can sleep
1321  *
1322  * See i2c_add_numbered_adapter() for details.
1323  */
1324 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1325 {
1326         int id;
1327
1328         mutex_lock(&core_lock);
1329         id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL);
1330         mutex_unlock(&core_lock);
1331         if (WARN(id < 0, "couldn't get idr"))
1332                 return id == -ENOSPC ? -EBUSY : id;
1333
1334         return i2c_register_adapter(adap);
1335 }
1336
1337 /**
1338  * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1339  * @adapter: the adapter to add
1340  * Context: can sleep
1341  *
1342  * This routine is used to declare an I2C adapter when its bus number
1343  * doesn't matter or when its bus number is specified by an dt alias.
1344  * Examples of bases when the bus number doesn't matter: I2C adapters
1345  * dynamically added by USB links or PCI plugin cards.
1346  *
1347  * When this returns zero, a new bus number was allocated and stored
1348  * in adap->nr, and the specified adapter became available for clients.
1349  * Otherwise, a negative errno value is returned.
1350  */
1351 int i2c_add_adapter(struct i2c_adapter *adapter)
1352 {
1353         struct device *dev = &adapter->dev;
1354         int id;
1355
1356         if (dev->of_node) {
1357                 id = of_alias_get_id(dev->of_node, "i2c");
1358                 if (id >= 0) {
1359                         adapter->nr = id;
1360                         return __i2c_add_numbered_adapter(adapter);
1361                 }
1362         }
1363
1364         mutex_lock(&core_lock);
1365         id = idr_alloc(&i2c_adapter_idr, adapter,
1366                        __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1367         mutex_unlock(&core_lock);
1368         if (WARN(id < 0, "couldn't get idr"))
1369                 return id;
1370
1371         adapter->nr = id;
1372
1373         return i2c_register_adapter(adapter);
1374 }
1375 EXPORT_SYMBOL(i2c_add_adapter);
1376
1377 /**
1378  * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1379  * @adap: the adapter to register (with adap->nr initialized)
1380  * Context: can sleep
1381  *
1382  * This routine is used to declare an I2C adapter when its bus number
1383  * matters.  For example, use it for I2C adapters from system-on-chip CPUs,
1384  * or otherwise built in to the system's mainboard, and where i2c_board_info
1385  * is used to properly configure I2C devices.
1386  *
1387  * If the requested bus number is set to -1, then this function will behave
1388  * identically to i2c_add_adapter, and will dynamically assign a bus number.
1389  *
1390  * If no devices have pre-been declared for this bus, then be sure to
1391  * register the adapter before any dynamically allocated ones.  Otherwise
1392  * the required bus ID may not be available.
1393  *
1394  * When this returns zero, the specified adapter became available for
1395  * clients using the bus number provided in adap->nr.  Also, the table
1396  * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1397  * and the appropriate driver model device nodes are created.  Otherwise, a
1398  * negative errno value is returned.
1399  */
1400 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1401 {
1402         if (adap->nr == -1) /* -1 means dynamically assign bus id */
1403                 return i2c_add_adapter(adap);
1404
1405         return __i2c_add_numbered_adapter(adap);
1406 }
1407 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1408
1409 static void i2c_do_del_adapter(struct i2c_driver *driver,
1410                               struct i2c_adapter *adapter)
1411 {
1412         struct i2c_client *client, *_n;
1413
1414         /* Remove the devices we created ourselves as the result of hardware
1415          * probing (using a driver's detect method) */
1416         list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1417                 if (client->adapter == adapter) {
1418                         dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1419                                 client->name, client->addr);
1420                         list_del(&client->detected);
1421                         i2c_unregister_device(client);
1422                 }
1423         }
1424 }
1425
1426 static int __unregister_client(struct device *dev, void *dummy)
1427 {
1428         struct i2c_client *client = i2c_verify_client(dev);
1429         if (client && strcmp(client->name, "dummy"))
1430                 i2c_unregister_device(client);
1431         return 0;
1432 }
1433
1434 static int __unregister_dummy(struct device *dev, void *dummy)
1435 {
1436         struct i2c_client *client = i2c_verify_client(dev);
1437         i2c_unregister_device(client);
1438         return 0;
1439 }
1440
1441 static int __process_removed_adapter(struct device_driver *d, void *data)
1442 {
1443         i2c_do_del_adapter(to_i2c_driver(d), data);
1444         return 0;
1445 }
1446
1447 /**
1448  * i2c_del_adapter - unregister I2C adapter
1449  * @adap: the adapter being unregistered
1450  * Context: can sleep
1451  *
1452  * This unregisters an I2C adapter which was previously registered
1453  * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1454  */
1455 void i2c_del_adapter(struct i2c_adapter *adap)
1456 {
1457         struct i2c_adapter *found;
1458         struct i2c_client *client, *next;
1459
1460         /* First make sure that this adapter was ever added */
1461         mutex_lock(&core_lock);
1462         found = idr_find(&i2c_adapter_idr, adap->nr);
1463         mutex_unlock(&core_lock);
1464         if (found != adap) {
1465                 pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
1466                 return;
1467         }
1468
1469         i2c_acpi_remove_space_handler(adap);
1470         /* Tell drivers about this removal */
1471         mutex_lock(&core_lock);
1472         bus_for_each_drv(&i2c_bus_type, NULL, adap,
1473                                __process_removed_adapter);
1474         mutex_unlock(&core_lock);
1475
1476         /* Remove devices instantiated from sysfs */
1477         mutex_lock_nested(&adap->userspace_clients_lock,
1478                           i2c_adapter_depth(adap));
1479         list_for_each_entry_safe(client, next, &adap->userspace_clients,
1480                                  detected) {
1481                 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1482                         client->addr);
1483                 list_del(&client->detected);
1484                 i2c_unregister_device(client);
1485         }
1486         mutex_unlock(&adap->userspace_clients_lock);
1487
1488         /* Detach any active clients. This can't fail, thus we do not
1489          * check the returned value. This is a two-pass process, because
1490          * we can't remove the dummy devices during the first pass: they
1491          * could have been instantiated by real devices wishing to clean
1492          * them up properly, so we give them a chance to do that first. */
1493         device_for_each_child(&adap->dev, NULL, __unregister_client);
1494         device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1495
1496 #ifdef CONFIG_I2C_COMPAT
1497         class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1498                                  adap->dev.parent);
1499 #endif
1500
1501         /* device name is gone after device_unregister */
1502         dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1503
1504         pm_runtime_disable(&adap->dev);
1505
1506         i2c_host_notify_irq_teardown(adap);
1507
1508         /* wait until all references to the device are gone
1509          *
1510          * FIXME: This is old code and should ideally be replaced by an
1511          * alternative which results in decoupling the lifetime of the struct
1512          * device from the i2c_adapter, like spi or netdev do. Any solution
1513          * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1514          */
1515         init_completion(&adap->dev_released);
1516         device_unregister(&adap->dev);
1517         wait_for_completion(&adap->dev_released);
1518
1519         /* free bus id */
1520         mutex_lock(&core_lock);
1521         idr_remove(&i2c_adapter_idr, adap->nr);
1522         mutex_unlock(&core_lock);
1523
1524         /* Clear the device structure in case this adapter is ever going to be
1525            added again */
1526         memset(&adap->dev, 0, sizeof(adap->dev));
1527 }
1528 EXPORT_SYMBOL(i2c_del_adapter);
1529
1530 /**
1531  * i2c_parse_fw_timings - get I2C related timing parameters from firmware
1532  * @dev: The device to scan for I2C timing properties
1533  * @t: the i2c_timings struct to be filled with values
1534  * @use_defaults: bool to use sane defaults derived from the I2C specification
1535  *                when properties are not found, otherwise use 0
1536  *
1537  * Scan the device for the generic I2C properties describing timing parameters
1538  * for the signal and fill the given struct with the results. If a property was
1539  * not found and use_defaults was true, then maximum timings are assumed which
1540  * are derived from the I2C specification. If use_defaults is not used, the
1541  * results will be 0, so drivers can apply their own defaults later. The latter
1542  * is mainly intended for avoiding regressions of existing drivers which want
1543  * to switch to this function. New drivers almost always should use the defaults.
1544  */
1545
1546 void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults)
1547 {
1548         int ret;
1549
1550         memset(t, 0, sizeof(*t));
1551
1552         ret = device_property_read_u32(dev, "clock-frequency", &t->bus_freq_hz);
1553         if (ret && use_defaults)
1554                 t->bus_freq_hz = 100000;
1555
1556         ret = device_property_read_u32(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns);
1557         if (ret && use_defaults) {
1558                 if (t->bus_freq_hz <= 100000)
1559                         t->scl_rise_ns = 1000;
1560                 else if (t->bus_freq_hz <= 400000)
1561                         t->scl_rise_ns = 300;
1562                 else
1563                         t->scl_rise_ns = 120;
1564         }
1565
1566         ret = device_property_read_u32(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns);
1567         if (ret && use_defaults) {
1568                 if (t->bus_freq_hz <= 400000)
1569                         t->scl_fall_ns = 300;
1570                 else
1571                         t->scl_fall_ns = 120;
1572         }
1573
1574         device_property_read_u32(dev, "i2c-scl-internal-delay-ns", &t->scl_int_delay_ns);
1575
1576         ret = device_property_read_u32(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns);
1577         if (ret && use_defaults)
1578                 t->sda_fall_ns = t->scl_fall_ns;
1579
1580         device_property_read_u32(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns);
1581 }
1582 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1583
1584 /* ------------------------------------------------------------------------- */
1585
1586 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
1587 {
1588         int res;
1589
1590         mutex_lock(&core_lock);
1591         res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1592         mutex_unlock(&core_lock);
1593
1594         return res;
1595 }
1596 EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1597
1598 static int __process_new_driver(struct device *dev, void *data)
1599 {
1600         if (dev->type != &i2c_adapter_type)
1601                 return 0;
1602         return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1603 }
1604
1605 /*
1606  * An i2c_driver is used with one or more i2c_client (device) nodes to access
1607  * i2c slave chips, on a bus instance associated with some i2c_adapter.
1608  */
1609
1610 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1611 {
1612         int res;
1613
1614         /* Can't register until after driver model init */
1615         if (WARN_ON(!is_registered))
1616                 return -EAGAIN;
1617
1618         /* add the driver to the list of i2c drivers in the driver core */
1619         driver->driver.owner = owner;
1620         driver->driver.bus = &i2c_bus_type;
1621         INIT_LIST_HEAD(&driver->clients);
1622
1623         /* When registration returns, the driver core
1624          * will have called probe() for all matching-but-unbound devices.
1625          */
1626         res = driver_register(&driver->driver);
1627         if (res)
1628                 return res;
1629
1630         pr_debug("driver [%s] registered\n", driver->driver.name);
1631
1632         /* Walk the adapters that are already present */
1633         i2c_for_each_dev(driver, __process_new_driver);
1634
1635         return 0;
1636 }
1637 EXPORT_SYMBOL(i2c_register_driver);
1638
1639 static int __process_removed_driver(struct device *dev, void *data)
1640 {
1641         if (dev->type == &i2c_adapter_type)
1642                 i2c_do_del_adapter(data, to_i2c_adapter(dev));
1643         return 0;
1644 }
1645
1646 /**
1647  * i2c_del_driver - unregister I2C driver
1648  * @driver: the driver being unregistered
1649  * Context: can sleep
1650  */
1651 void i2c_del_driver(struct i2c_driver *driver)
1652 {
1653         i2c_for_each_dev(driver, __process_removed_driver);
1654
1655         driver_unregister(&driver->driver);
1656         pr_debug("driver [%s] unregistered\n", driver->driver.name);
1657 }
1658 EXPORT_SYMBOL(i2c_del_driver);
1659
1660 /* ------------------------------------------------------------------------- */
1661
1662 /**
1663  * i2c_use_client - increments the reference count of the i2c client structure
1664  * @client: the client being referenced
1665  *
1666  * Each live reference to a client should be refcounted. The driver model does
1667  * that automatically as part of driver binding, so that most drivers don't
1668  * need to do this explicitly: they hold a reference until they're unbound
1669  * from the device.
1670  *
1671  * A pointer to the client with the incremented reference counter is returned.
1672  */
1673 struct i2c_client *i2c_use_client(struct i2c_client *client)
1674 {
1675         if (client && get_device(&client->dev))
1676                 return client;
1677         return NULL;
1678 }
1679 EXPORT_SYMBOL(i2c_use_client);
1680
1681 /**
1682  * i2c_release_client - release a use of the i2c client structure
1683  * @client: the client being no longer referenced
1684  *
1685  * Must be called when a user of a client is finished with it.
1686  */
1687 void i2c_release_client(struct i2c_client *client)
1688 {
1689         if (client)
1690                 put_device(&client->dev);
1691 }
1692 EXPORT_SYMBOL(i2c_release_client);
1693
1694 struct i2c_cmd_arg {
1695         unsigned        cmd;
1696         void            *arg;
1697 };
1698
1699 static int i2c_cmd(struct device *dev, void *_arg)
1700 {
1701         struct i2c_client       *client = i2c_verify_client(dev);
1702         struct i2c_cmd_arg      *arg = _arg;
1703         struct i2c_driver       *driver;
1704
1705         if (!client || !client->dev.driver)
1706                 return 0;
1707
1708         driver = to_i2c_driver(client->dev.driver);
1709         if (driver->command)
1710                 driver->command(client, arg->cmd, arg->arg);
1711         return 0;
1712 }
1713
1714 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1715 {
1716         struct i2c_cmd_arg      cmd_arg;
1717
1718         cmd_arg.cmd = cmd;
1719         cmd_arg.arg = arg;
1720         device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1721 }
1722 EXPORT_SYMBOL(i2c_clients_command);
1723
1724 static int __init i2c_init(void)
1725 {
1726         int retval;
1727
1728         retval = of_alias_get_highest_id("i2c");
1729
1730         down_write(&__i2c_board_lock);
1731         if (retval >= __i2c_first_dynamic_bus_num)
1732                 __i2c_first_dynamic_bus_num = retval + 1;
1733         up_write(&__i2c_board_lock);
1734
1735         retval = bus_register(&i2c_bus_type);
1736         if (retval)
1737                 return retval;
1738
1739         is_registered = true;
1740
1741 #ifdef CONFIG_I2C_COMPAT
1742         i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1743         if (!i2c_adapter_compat_class) {
1744                 retval = -ENOMEM;
1745                 goto bus_err;
1746         }
1747 #endif
1748         retval = i2c_add_driver(&dummy_driver);
1749         if (retval)
1750                 goto class_err;
1751
1752         if (IS_ENABLED(CONFIG_OF_DYNAMIC))
1753                 WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
1754         if (IS_ENABLED(CONFIG_ACPI))
1755                 WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
1756
1757         return 0;
1758
1759 class_err:
1760 #ifdef CONFIG_I2C_COMPAT
1761         class_compat_unregister(i2c_adapter_compat_class);
1762 bus_err:
1763 #endif
1764         is_registered = false;
1765         bus_unregister(&i2c_bus_type);
1766         return retval;
1767 }
1768
1769 static void __exit i2c_exit(void)
1770 {
1771         if (IS_ENABLED(CONFIG_ACPI))
1772                 WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
1773         if (IS_ENABLED(CONFIG_OF_DYNAMIC))
1774                 WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
1775         i2c_del_driver(&dummy_driver);
1776 #ifdef CONFIG_I2C_COMPAT
1777         class_compat_unregister(i2c_adapter_compat_class);
1778 #endif
1779         bus_unregister(&i2c_bus_type);
1780         tracepoint_synchronize_unregister();
1781 }
1782
1783 /* We must initialize early, because some subsystems register i2c drivers
1784  * in subsys_initcall() code, but are linked (and initialized) before i2c.
1785  */
1786 postcore_initcall(i2c_init);
1787 module_exit(i2c_exit);
1788
1789 /* ----------------------------------------------------
1790  * the functional interface to the i2c busses.
1791  * ----------------------------------------------------
1792  */
1793
1794 /* Check if val is exceeding the quirk IFF quirk is non 0 */
1795 #define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
1796
1797 static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
1798 {
1799         dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
1800                             err_msg, msg->addr, msg->len,
1801                             msg->flags & I2C_M_RD ? "read" : "write");
1802         return -EOPNOTSUPP;
1803 }
1804
1805 static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1806 {
1807         const struct i2c_adapter_quirks *q = adap->quirks;
1808         int max_num = q->max_num_msgs, i;
1809         bool do_len_check = true;
1810
1811         if (q->flags & I2C_AQ_COMB) {
1812                 max_num = 2;
1813
1814                 /* special checks for combined messages */
1815                 if (num == 2) {
1816                         if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
1817                                 return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
1818
1819                         if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
1820                                 return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
1821
1822                         if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
1823                                 return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
1824
1825                         if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
1826                                 return i2c_quirk_error(adap, &msgs[0], "msg too long");
1827
1828                         if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
1829                                 return i2c_quirk_error(adap, &msgs[1], "msg too long");
1830
1831                         do_len_check = false;
1832                 }
1833         }
1834
1835         if (i2c_quirk_exceeded(num, max_num))
1836                 return i2c_quirk_error(adap, &msgs[0], "too many messages");
1837
1838         for (i = 0; i < num; i++) {
1839                 u16 len = msgs[i].len;
1840
1841                 if (msgs[i].flags & I2C_M_RD) {
1842                         if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
1843                                 return i2c_quirk_error(adap, &msgs[i], "msg too long");
1844
1845                         if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0)
1846                                 return i2c_quirk_error(adap, &msgs[i], "no zero length");
1847                 } else {
1848                         if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
1849                                 return i2c_quirk_error(adap, &msgs[i], "msg too long");
1850
1851                         if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0)
1852                                 return i2c_quirk_error(adap, &msgs[i], "no zero length");
1853                 }
1854         }
1855
1856         return 0;
1857 }
1858
1859 /**
1860  * __i2c_transfer - unlocked flavor of i2c_transfer
1861  * @adap: Handle to I2C bus
1862  * @msgs: One or more messages to execute before STOP is issued to
1863  *      terminate the operation; each message begins with a START.
1864  * @num: Number of messages to be executed.
1865  *
1866  * Returns negative errno, else the number of messages executed.
1867  *
1868  * Adapter lock must be held when calling this function. No debug logging
1869  * takes place. adap->algo->master_xfer existence isn't checked.
1870  */
1871 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1872 {
1873         unsigned long orig_jiffies;
1874         int ret, try;
1875
1876         if (WARN_ON(!msgs || num < 1))
1877                 return -EINVAL;
1878
1879         if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
1880                 return -EOPNOTSUPP;
1881
1882         /*
1883          * i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
1884          * enabled.  This is an efficient way of keeping the for-loop from
1885          * being executed when not needed.
1886          */
1887         if (static_branch_unlikely(&i2c_trace_msg_key)) {
1888                 int i;
1889                 for (i = 0; i < num; i++)
1890                         if (msgs[i].flags & I2C_M_RD)
1891                                 trace_i2c_read(adap, &msgs[i], i);
1892                         else
1893                                 trace_i2c_write(adap, &msgs[i], i);
1894         }
1895
1896         /* Retry automatically on arbitration loss */
1897         orig_jiffies = jiffies;
1898         for (ret = 0, try = 0; try <= adap->retries; try++) {
1899                 ret = adap->algo->master_xfer(adap, msgs, num);
1900                 if (ret != -EAGAIN)
1901                         break;
1902                 if (time_after(jiffies, orig_jiffies + adap->timeout))
1903                         break;
1904         }
1905
1906         if (static_branch_unlikely(&i2c_trace_msg_key)) {
1907                 int i;
1908                 for (i = 0; i < ret; i++)
1909                         if (msgs[i].flags & I2C_M_RD)
1910                                 trace_i2c_reply(adap, &msgs[i], i);
1911                 trace_i2c_result(adap, num, ret);
1912         }
1913
1914         return ret;
1915 }
1916 EXPORT_SYMBOL(__i2c_transfer);
1917
1918 /**
1919  * i2c_transfer - execute a single or combined I2C message
1920  * @adap: Handle to I2C bus
1921  * @msgs: One or more messages to execute before STOP is issued to
1922  *      terminate the operation; each message begins with a START.
1923  * @num: Number of messages to be executed.
1924  *
1925  * Returns negative errno, else the number of messages executed.
1926  *
1927  * Note that there is no requirement that each message be sent to
1928  * the same slave address, although that is the most common model.
1929  */
1930 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1931 {
1932         int ret;
1933
1934         /* REVISIT the fault reporting model here is weak:
1935          *
1936          *  - When we get an error after receiving N bytes from a slave,
1937          *    there is no way to report "N".
1938          *
1939          *  - When we get a NAK after transmitting N bytes to a slave,
1940          *    there is no way to report "N" ... or to let the master
1941          *    continue executing the rest of this combined message, if
1942          *    that's the appropriate response.
1943          *
1944          *  - When for example "num" is two and we successfully complete
1945          *    the first message but get an error part way through the
1946          *    second, it's unclear whether that should be reported as
1947          *    one (discarding status on the second message) or errno
1948          *    (discarding status on the first one).
1949          */
1950
1951         if (adap->algo->master_xfer) {
1952 #ifdef DEBUG
1953                 for (ret = 0; ret < num; ret++) {
1954                         dev_dbg(&adap->dev,
1955                                 "master_xfer[%d] %c, addr=0x%02x, len=%d%s\n",
1956                                 ret, (msgs[ret].flags & I2C_M_RD) ? 'R' : 'W',
1957                                 msgs[ret].addr, msgs[ret].len,
1958                                 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1959                 }
1960 #endif
1961
1962                 if (in_atomic() || irqs_disabled()) {
1963                         ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT);
1964                         if (!ret)
1965                                 /* I2C activity is ongoing. */
1966                                 return -EAGAIN;
1967                 } else {
1968                         i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
1969                 }
1970
1971                 ret = __i2c_transfer(adap, msgs, num);
1972                 i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
1973
1974                 return ret;
1975         } else {
1976                 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1977                 return -EOPNOTSUPP;
1978         }
1979 }
1980 EXPORT_SYMBOL(i2c_transfer);
1981
1982 /**
1983  * i2c_transfer_buffer_flags - issue a single I2C message transferring data
1984  *                             to/from a buffer
1985  * @client: Handle to slave device
1986  * @buf: Where the data is stored
1987  * @count: How many bytes to transfer, must be less than 64k since msg.len is u16
1988  * @flags: The flags to be used for the message, e.g. I2C_M_RD for reads
1989  *
1990  * Returns negative errno, or else the number of bytes transferred.
1991  */
1992 int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf,
1993                               int count, u16 flags)
1994 {
1995         int ret;
1996         struct i2c_msg msg = {
1997                 .addr = client->addr,
1998                 .flags = flags | (client->flags & I2C_M_TEN),
1999                 .len = count,
2000                 .buf = buf,
2001         };
2002
2003         ret = i2c_transfer(client->adapter, &msg, 1);
2004
2005         /*
2006          * If everything went ok (i.e. 1 msg transferred), return #bytes
2007          * transferred, else error code.
2008          */
2009         return (ret == 1) ? count : ret;
2010 }
2011 EXPORT_SYMBOL(i2c_transfer_buffer_flags);
2012
2013 /**
2014  * i2c_get_device_id - get manufacturer, part id and die revision of a device
2015  * @client: The device to query
2016  * @id: The queried information
2017  *
2018  * Returns negative errno on error, zero on success.
2019  */
2020 int i2c_get_device_id(const struct i2c_client *client,
2021                       struct i2c_device_identity *id)
2022 {
2023         struct i2c_adapter *adap = client->adapter;
2024         union i2c_smbus_data raw_id;
2025         int ret;
2026
2027         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
2028                 return -EOPNOTSUPP;
2029
2030         raw_id.block[0] = 3;
2031         ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0,
2032                              I2C_SMBUS_READ, client->addr << 1,
2033                              I2C_SMBUS_I2C_BLOCK_DATA, &raw_id);
2034         if (ret)
2035                 return ret;
2036
2037         id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4);
2038         id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3);
2039         id->die_revision = raw_id.block[3] & 0x7;
2040         return 0;
2041 }
2042 EXPORT_SYMBOL_GPL(i2c_get_device_id);
2043
2044 /* ----------------------------------------------------
2045  * the i2c address scanning function
2046  * Will not work for 10-bit addresses!
2047  * ----------------------------------------------------
2048  */
2049
2050 /*
2051  * Legacy default probe function, mostly relevant for SMBus. The default
2052  * probe method is a quick write, but it is known to corrupt the 24RF08
2053  * EEPROMs due to a state machine bug, and could also irreversibly
2054  * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2055  * we use a short byte read instead. Also, some bus drivers don't implement
2056  * quick write, so we fallback to a byte read in that case too.
2057  * On x86, there is another special case for FSC hardware monitoring chips,
2058  * which want regular byte reads (address 0x73.) Fortunately, these are the
2059  * only known chips using this I2C address on PC hardware.
2060  * Returns 1 if probe succeeded, 0 if not.
2061  */
2062 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
2063 {
2064         int err;
2065         union i2c_smbus_data dummy;
2066
2067 #ifdef CONFIG_X86
2068         if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
2069          && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2070                 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2071                                      I2C_SMBUS_BYTE_DATA, &dummy);
2072         else
2073 #endif
2074         if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
2075          && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2076                 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
2077                                      I2C_SMBUS_QUICK, NULL);
2078         else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2079                 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2080                                      I2C_SMBUS_BYTE, &dummy);
2081         else {
2082                 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2083                          addr);
2084                 err = -EOPNOTSUPP;
2085         }
2086
2087         return err >= 0;
2088 }
2089
2090 static int i2c_detect_address(struct i2c_client *temp_client,
2091                               struct i2c_driver *driver)
2092 {
2093         struct i2c_board_info info;
2094         struct i2c_adapter *adapter = temp_client->adapter;
2095         int addr = temp_client->addr;
2096         int err;
2097
2098         /* Make sure the address is valid */
2099         err = i2c_check_7bit_addr_validity_strict(addr);
2100         if (err) {
2101                 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2102                          addr);
2103                 return err;
2104         }
2105
2106         /* Skip if already in use (7 bit, no need to encode flags) */
2107         if (i2c_check_addr_busy(adapter, addr))
2108                 return 0;
2109
2110         /* Make sure there is something at this address */
2111         if (!i2c_default_probe(adapter, addr))
2112                 return 0;
2113
2114         /* Finally call the custom detection function */
2115         memset(&info, 0, sizeof(struct i2c_board_info));
2116         info.addr = addr;
2117         err = driver->detect(temp_client, &info);
2118         if (err) {
2119                 /* -ENODEV is returned if the detection fails. We catch it
2120                    here as this isn't an error. */
2121                 return err == -ENODEV ? 0 : err;
2122         }
2123
2124         /* Consistency check */
2125         if (info.type[0] == '\0') {
2126                 dev_err(&adapter->dev,
2127                         "%s detection function provided no name for 0x%x\n",
2128                         driver->driver.name, addr);
2129         } else {
2130                 struct i2c_client *client;
2131
2132                 /* Detection succeeded, instantiate the device */
2133                 if (adapter->class & I2C_CLASS_DEPRECATED)
2134                         dev_warn(&adapter->dev,
2135                                 "This adapter will soon drop class based instantiation of devices. "
2136                                 "Please make sure client 0x%02x gets instantiated by other means. "
2137                                 "Check 'Documentation/i2c/instantiating-devices' for details.\n",
2138                                 info.addr);
2139
2140                 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2141                         info.type, info.addr);
2142                 client = i2c_new_device(adapter, &info);
2143                 if (client)
2144                         list_add_tail(&client->detected, &driver->clients);
2145                 else
2146                         dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2147                                 info.type, info.addr);
2148         }
2149         return 0;
2150 }
2151
2152 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
2153 {
2154         const unsigned short *address_list;
2155         struct i2c_client *temp_client;
2156         int i, err = 0;
2157         int adap_id = i2c_adapter_id(adapter);
2158
2159         address_list = driver->address_list;
2160         if (!driver->detect || !address_list)
2161                 return 0;
2162
2163         /* Warn that the adapter lost class based instantiation */
2164         if (adapter->class == I2C_CLASS_DEPRECATED) {
2165                 dev_dbg(&adapter->dev,
2166                         "This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
2167                         "If you need it, check 'Documentation/i2c/instantiating-devices' for alternatives.\n",
2168                         driver->driver.name);
2169                 return 0;
2170         }
2171
2172         /* Stop here if the classes do not match */
2173         if (!(adapter->class & driver->class))
2174                 return 0;
2175
2176         /* Set up a temporary client to help detect callback */
2177         temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
2178         if (!temp_client)
2179                 return -ENOMEM;
2180         temp_client->adapter = adapter;
2181
2182         for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
2183                 dev_dbg(&adapter->dev,
2184                         "found normal entry for adapter %d, addr 0x%02x\n",
2185                         adap_id, address_list[i]);
2186                 temp_client->addr = address_list[i];
2187                 err = i2c_detect_address(temp_client, driver);
2188                 if (unlikely(err))
2189                         break;
2190         }
2191
2192         kfree(temp_client);
2193         return err;
2194 }
2195
2196 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
2197 {
2198         return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2199                               I2C_SMBUS_QUICK, NULL) >= 0;
2200 }
2201 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2202
2203 struct i2c_client *
2204 i2c_new_probed_device(struct i2c_adapter *adap,
2205                       struct i2c_board_info *info,
2206                       unsigned short const *addr_list,
2207                       int (*probe)(struct i2c_adapter *, unsigned short addr))
2208 {
2209         int i;
2210
2211         if (!probe)
2212                 probe = i2c_default_probe;
2213
2214         for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
2215                 /* Check address validity */
2216                 if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) {
2217                         dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
2218                                  addr_list[i]);
2219                         continue;
2220                 }
2221
2222                 /* Check address availability (7 bit, no need to encode flags) */
2223                 if (i2c_check_addr_busy(adap, addr_list[i])) {
2224                         dev_dbg(&adap->dev,
2225                                 "Address 0x%02x already in use, not probing\n",
2226                                 addr_list[i]);
2227                         continue;
2228                 }
2229
2230                 /* Test address responsiveness */
2231                 if (probe(adap, addr_list[i]))
2232                         break;
2233         }
2234
2235         if (addr_list[i] == I2C_CLIENT_END) {
2236                 dev_dbg(&adap->dev, "Probing failed, no device found\n");
2237                 return NULL;
2238         }
2239
2240         info->addr = addr_list[i];
2241         return i2c_new_device(adap, info);
2242 }
2243 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
2244
2245 struct i2c_adapter *i2c_get_adapter(int nr)
2246 {
2247         struct i2c_adapter *adapter;
2248
2249         mutex_lock(&core_lock);
2250         adapter = idr_find(&i2c_adapter_idr, nr);
2251         if (!adapter)
2252                 goto exit;
2253
2254         if (try_module_get(adapter->owner))
2255                 get_device(&adapter->dev);
2256         else
2257                 adapter = NULL;
2258
2259  exit:
2260         mutex_unlock(&core_lock);
2261         return adapter;
2262 }
2263 EXPORT_SYMBOL(i2c_get_adapter);
2264
2265 void i2c_put_adapter(struct i2c_adapter *adap)
2266 {
2267         if (!adap)
2268                 return;
2269
2270         put_device(&adap->dev);
2271         module_put(adap->owner);
2272 }
2273 EXPORT_SYMBOL(i2c_put_adapter);
2274
2275 /**
2276  * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
2277  * @msg: the message to be checked
2278  * @threshold: the minimum number of bytes for which using DMA makes sense
2279  *
2280  * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
2281  *         Or a valid pointer to be used with DMA. After use, release it by
2282  *         calling i2c_release_dma_safe_msg_buf().
2283  *
2284  * This function must only be called from process context!
2285  */
2286 u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)
2287 {
2288         if (msg->len < threshold)
2289                 return NULL;
2290
2291         if (msg->flags & I2C_M_DMA_SAFE)
2292                 return msg->buf;
2293
2294         pr_debug("using bounce buffer for addr=0x%02x, len=%d\n",
2295                  msg->addr, msg->len);
2296
2297         if (msg->flags & I2C_M_RD)
2298                 return kzalloc(msg->len, GFP_KERNEL);
2299         else
2300                 return kmemdup(msg->buf, msg->len, GFP_KERNEL);
2301 }
2302 EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);
2303
2304 /**
2305  * i2c_release_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
2306  * @msg: the message to be synced with
2307  * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
2308  */
2309 void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf)
2310 {
2311         if (!buf || buf == msg->buf)
2312                 return;
2313
2314         if (msg->flags & I2C_M_RD)
2315                 memcpy(msg->buf, buf, msg->len);
2316
2317         kfree(buf);
2318 }
2319 EXPORT_SYMBOL_GPL(i2c_release_dma_safe_msg_buf);
2320
2321 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2322 MODULE_DESCRIPTION("I2C-Bus main module");
2323 MODULE_LICENSE("GPL");