Merge tag 'backlight-next-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee...
[muen/linux.git] / drivers / video / backlight / pwm_bl.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Simple PWM based backlight control, board code has to setup
4  * 1) pin configuration so PWM waveforms can output
5  * 2) platform_data being correctly configured
6  */
7
8 #include <linux/delay.h>
9 #include <linux/gpio/consumer.h>
10 #include <linux/gpio.h>
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <linux/platform_device.h>
15 #include <linux/fb.h>
16 #include <linux/backlight.h>
17 #include <linux/err.h>
18 #include <linux/pwm.h>
19 #include <linux/pwm_backlight.h>
20 #include <linux/regulator/consumer.h>
21 #include <linux/slab.h>
22
23 struct pwm_bl_data {
24         struct pwm_device       *pwm;
25         struct device           *dev;
26         unsigned int            lth_brightness;
27         unsigned int            *levels;
28         bool                    enabled;
29         struct regulator        *power_supply;
30         struct gpio_desc        *enable_gpio;
31         unsigned int            scale;
32         bool                    legacy;
33         unsigned int            post_pwm_on_delay;
34         unsigned int            pwm_off_delay;
35         int                     (*notify)(struct device *,
36                                           int brightness);
37         void                    (*notify_after)(struct device *,
38                                         int brightness);
39         int                     (*check_fb)(struct device *, struct fb_info *);
40         void                    (*exit)(struct device *);
41 };
42
43 static void pwm_backlight_power_on(struct pwm_bl_data *pb)
44 {
45         struct pwm_state state;
46         int err;
47
48         pwm_get_state(pb->pwm, &state);
49         if (pb->enabled)
50                 return;
51
52         err = regulator_enable(pb->power_supply);
53         if (err < 0)
54                 dev_err(pb->dev, "failed to enable power supply\n");
55
56         state.enabled = true;
57         pwm_apply_state(pb->pwm, &state);
58
59         if (pb->post_pwm_on_delay)
60                 msleep(pb->post_pwm_on_delay);
61
62         if (pb->enable_gpio)
63                 gpiod_set_value_cansleep(pb->enable_gpio, 1);
64
65         pb->enabled = true;
66 }
67
68 static void pwm_backlight_power_off(struct pwm_bl_data *pb)
69 {
70         struct pwm_state state;
71
72         pwm_get_state(pb->pwm, &state);
73         if (!pb->enabled)
74                 return;
75
76         if (pb->enable_gpio)
77                 gpiod_set_value_cansleep(pb->enable_gpio, 0);
78
79         if (pb->pwm_off_delay)
80                 msleep(pb->pwm_off_delay);
81
82         state.enabled = false;
83         state.duty_cycle = 0;
84         pwm_apply_state(pb->pwm, &state);
85
86         regulator_disable(pb->power_supply);
87         pb->enabled = false;
88 }
89
90 static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
91 {
92         unsigned int lth = pb->lth_brightness;
93         struct pwm_state state;
94         u64 duty_cycle;
95
96         pwm_get_state(pb->pwm, &state);
97
98         if (pb->levels)
99                 duty_cycle = pb->levels[brightness];
100         else
101                 duty_cycle = brightness;
102
103         duty_cycle *= state.period - lth;
104         do_div(duty_cycle, pb->scale);
105
106         return duty_cycle + lth;
107 }
108
109 static int pwm_backlight_update_status(struct backlight_device *bl)
110 {
111         struct pwm_bl_data *pb = bl_get_data(bl);
112         int brightness = bl->props.brightness;
113         struct pwm_state state;
114
115         if (bl->props.power != FB_BLANK_UNBLANK ||
116             bl->props.fb_blank != FB_BLANK_UNBLANK ||
117             bl->props.state & BL_CORE_FBBLANK)
118                 brightness = 0;
119
120         if (pb->notify)
121                 brightness = pb->notify(pb->dev, brightness);
122
123         if (brightness > 0) {
124                 pwm_get_state(pb->pwm, &state);
125                 state.duty_cycle = compute_duty_cycle(pb, brightness);
126                 pwm_apply_state(pb->pwm, &state);
127                 pwm_backlight_power_on(pb);
128         } else
129                 pwm_backlight_power_off(pb);
130
131         if (pb->notify_after)
132                 pb->notify_after(pb->dev, brightness);
133
134         return 0;
135 }
136
137 static int pwm_backlight_check_fb(struct backlight_device *bl,
138                                   struct fb_info *info)
139 {
140         struct pwm_bl_data *pb = bl_get_data(bl);
141
142         return !pb->check_fb || pb->check_fb(pb->dev, info);
143 }
144
145 static const struct backlight_ops pwm_backlight_ops = {
146         .update_status  = pwm_backlight_update_status,
147         .check_fb       = pwm_backlight_check_fb,
148 };
149
150 #ifdef CONFIG_OF
151 #define PWM_LUMINANCE_SCALE     10000 /* luminance scale */
152
153 /*
154  * CIE lightness to PWM conversion.
155  *
156  * The CIE 1931 lightness formula is what actually describes how we perceive
157  * light:
158  *          Y = (L* / 902.3)           if L* ≤ 0.08856
159  *          Y = ((L* + 16) / 116)^3    if L* > 0.08856
160  *
161  * Where Y is the luminance, the amount of light coming out of the screen, and
162  * is a number between 0.0 and 1.0; and L* is the lightness, how bright a human
163  * perceives the screen to be, and is a number between 0 and 100.
164  *
165  * The following function does the fixed point maths needed to implement the
166  * above formula.
167  */
168 static u64 cie1931(unsigned int lightness, unsigned int scale)
169 {
170         u64 retval;
171
172         lightness *= 100;
173         if (lightness <= (8 * scale)) {
174                 retval = DIV_ROUND_CLOSEST_ULL(lightness * 10, 9023);
175         } else {
176                 retval = int_pow((lightness + (16 * scale)) / 116, 3);
177                 retval = DIV_ROUND_CLOSEST_ULL(retval, (scale * scale));
178         }
179
180         return retval;
181 }
182
183 /*
184  * Create a default correction table for PWM values to create linear brightness
185  * for LED based backlights using the CIE1931 algorithm.
186  */
187 static
188 int pwm_backlight_brightness_default(struct device *dev,
189                                      struct platform_pwm_backlight_data *data,
190                                      unsigned int period)
191 {
192         unsigned int i;
193         u64 retval;
194
195         /*
196          * Once we have 4096 levels there's little point going much higher...
197          * neither interactive sliders nor animation benefits from having
198          * more values in the table.
199          */
200         data->max_brightness =
201                 min((int)DIV_ROUND_UP(period, fls(period)), 4096);
202
203         data->levels = devm_kcalloc(dev, data->max_brightness,
204                                     sizeof(*data->levels), GFP_KERNEL);
205         if (!data->levels)
206                 return -ENOMEM;
207
208         /* Fill the table using the cie1931 algorithm */
209         for (i = 0; i < data->max_brightness; i++) {
210                 retval = cie1931((i * PWM_LUMINANCE_SCALE) /
211                                  data->max_brightness, PWM_LUMINANCE_SCALE) *
212                                  period;
213                 retval = DIV_ROUND_CLOSEST_ULL(retval, PWM_LUMINANCE_SCALE);
214                 if (retval > UINT_MAX)
215                         return -EINVAL;
216                 data->levels[i] = (unsigned int)retval;
217         }
218
219         data->dft_brightness = data->max_brightness / 2;
220         data->max_brightness--;
221
222         return 0;
223 }
224
225 static int pwm_backlight_parse_dt(struct device *dev,
226                                   struct platform_pwm_backlight_data *data)
227 {
228         struct device_node *node = dev->of_node;
229         unsigned int num_levels = 0;
230         unsigned int levels_count;
231         unsigned int num_steps = 0;
232         struct property *prop;
233         unsigned int *table;
234         int length;
235         u32 value;
236         int ret;
237
238         if (!node)
239                 return -ENODEV;
240
241         memset(data, 0, sizeof(*data));
242
243         /*
244          * These values are optional and set as 0 by default, the out values
245          * are modified only if a valid u32 value can be decoded.
246          */
247         of_property_read_u32(node, "post-pwm-on-delay-ms",
248                              &data->post_pwm_on_delay);
249         of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
250
251         data->enable_gpio = -EINVAL;
252
253         /*
254          * Determine the number of brightness levels, if this property is not
255          * set a default table of brightness levels will be used.
256          */
257         prop = of_find_property(node, "brightness-levels", &length);
258         if (!prop)
259                 return 0;
260
261         data->max_brightness = length / sizeof(u32);
262
263         /* read brightness levels from DT property */
264         if (data->max_brightness > 0) {
265                 size_t size = sizeof(*data->levels) * data->max_brightness;
266                 unsigned int i, j, n = 0;
267
268                 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
269                 if (!data->levels)
270                         return -ENOMEM;
271
272                 ret = of_property_read_u32_array(node, "brightness-levels",
273                                                  data->levels,
274                                                  data->max_brightness);
275                 if (ret < 0)
276                         return ret;
277
278                 ret = of_property_read_u32(node, "default-brightness-level",
279                                            &value);
280                 if (ret < 0)
281                         return ret;
282
283                 data->dft_brightness = value;
284
285                 /*
286                  * This property is optional, if is set enables linear
287                  * interpolation between each of the values of brightness levels
288                  * and creates a new pre-computed table.
289                  */
290                 of_property_read_u32(node, "num-interpolated-steps",
291                                      &num_steps);
292
293                 /*
294                  * Make sure that there is at least two entries in the
295                  * brightness-levels table, otherwise we can't interpolate
296                  * between two points.
297                  */
298                 if (num_steps) {
299                         if (data->max_brightness < 2) {
300                                 dev_err(dev, "can't interpolate\n");
301                                 return -EINVAL;
302                         }
303
304                         /*
305                          * Recalculate the number of brightness levels, now
306                          * taking in consideration the number of interpolated
307                          * steps between two levels.
308                          */
309                         for (i = 0; i < data->max_brightness - 1; i++) {
310                                 if ((data->levels[i + 1] - data->levels[i]) /
311                                    num_steps)
312                                         num_levels += num_steps;
313                                 else
314                                         num_levels++;
315                         }
316                         num_levels++;
317                         dev_dbg(dev, "new number of brightness levels: %d\n",
318                                 num_levels);
319
320                         /*
321                          * Create a new table of brightness levels with all the
322                          * interpolated steps.
323                          */
324                         size = sizeof(*table) * num_levels;
325                         table = devm_kzalloc(dev, size, GFP_KERNEL);
326                         if (!table)
327                                 return -ENOMEM;
328
329                         /* Fill the interpolated table. */
330                         levels_count = 0;
331                         for (i = 0; i < data->max_brightness - 1; i++) {
332                                 value = data->levels[i];
333                                 n = (data->levels[i + 1] - value) / num_steps;
334                                 if (n > 0) {
335                                         for (j = 0; j < num_steps; j++) {
336                                                 table[levels_count] = value;
337                                                 value += n;
338                                                 levels_count++;
339                                         }
340                                 } else {
341                                         table[levels_count] = data->levels[i];
342                                         levels_count++;
343                                 }
344                         }
345                         table[levels_count] = data->levels[i];
346
347                         /*
348                          * As we use interpolation lets remove current
349                          * brightness levels table and replace for the
350                          * new interpolated table.
351                          */
352                         devm_kfree(dev, data->levels);
353                         data->levels = table;
354
355                         /*
356                          * Reassign max_brightness value to the new total number
357                          * of brightness levels.
358                          */
359                         data->max_brightness = num_levels;
360                 }
361
362                 data->max_brightness--;
363         }
364
365         return 0;
366 }
367
368 static const struct of_device_id pwm_backlight_of_match[] = {
369         { .compatible = "pwm-backlight" },
370         { }
371 };
372
373 MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
374 #else
375 static int pwm_backlight_parse_dt(struct device *dev,
376                                   struct platform_pwm_backlight_data *data)
377 {
378         return -ENODEV;
379 }
380
381 static
382 int pwm_backlight_brightness_default(struct device *dev,
383                                      struct platform_pwm_backlight_data *data,
384                                      unsigned int period)
385 {
386         return -ENODEV;
387 }
388 #endif
389
390 static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
391 {
392         struct device_node *node = pb->dev->of_node;
393
394         /* Not booted with device tree or no phandle link to the node */
395         if (!node || !node->phandle)
396                 return FB_BLANK_UNBLANK;
397
398         /*
399          * If the driver is probed from the device tree and there is a
400          * phandle link pointing to the backlight node, it is safe to
401          * assume that another driver will enable the backlight at the
402          * appropriate time. Therefore, if it is disabled, keep it so.
403          */
404
405         /* if the enable GPIO is disabled, do not enable the backlight */
406         if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
407                 return FB_BLANK_POWERDOWN;
408
409         /* The regulator is disabled, do not enable the backlight */
410         if (!regulator_is_enabled(pb->power_supply))
411                 return FB_BLANK_POWERDOWN;
412
413         /* The PWM is disabled, keep it like this */
414         if (!pwm_is_enabled(pb->pwm))
415                 return FB_BLANK_POWERDOWN;
416
417         return FB_BLANK_UNBLANK;
418 }
419
420 static int pwm_backlight_probe(struct platform_device *pdev)
421 {
422         struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
423         struct platform_pwm_backlight_data defdata;
424         struct backlight_properties props;
425         struct backlight_device *bl;
426         struct device_node *node = pdev->dev.of_node;
427         struct pwm_bl_data *pb;
428         struct pwm_state state;
429         unsigned int i;
430         int ret;
431
432         if (!data) {
433                 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
434                 if (ret < 0) {
435                         dev_err(&pdev->dev, "failed to find platform data\n");
436                         return ret;
437                 }
438
439                 data = &defdata;
440         }
441
442         if (data->init) {
443                 ret = data->init(&pdev->dev);
444                 if (ret < 0)
445                         return ret;
446         }
447
448         pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
449         if (!pb) {
450                 ret = -ENOMEM;
451                 goto err_alloc;
452         }
453
454         pb->notify = data->notify;
455         pb->notify_after = data->notify_after;
456         pb->check_fb = data->check_fb;
457         pb->exit = data->exit;
458         pb->dev = &pdev->dev;
459         pb->enabled = false;
460         pb->post_pwm_on_delay = data->post_pwm_on_delay;
461         pb->pwm_off_delay = data->pwm_off_delay;
462
463         pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
464                                                   GPIOD_ASIS);
465         if (IS_ERR(pb->enable_gpio)) {
466                 ret = PTR_ERR(pb->enable_gpio);
467                 goto err_alloc;
468         }
469
470         /*
471          * Compatibility fallback for drivers still using the integer GPIO
472          * platform data. Must go away soon.
473          */
474         if (!pb->enable_gpio && gpio_is_valid(data->enable_gpio)) {
475                 ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
476                                             GPIOF_OUT_INIT_HIGH, "enable");
477                 if (ret < 0) {
478                         dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
479                                 data->enable_gpio, ret);
480                         goto err_alloc;
481                 }
482
483                 pb->enable_gpio = gpio_to_desc(data->enable_gpio);
484         }
485
486         /*
487          * If the GPIO is not known to be already configured as output, that
488          * is, if gpiod_get_direction returns either 1 or -EINVAL, change the
489          * direction to output and set the GPIO as active.
490          * Do not force the GPIO to active when it was already output as it
491          * could cause backlight flickering or we would enable the backlight too
492          * early. Leave the decision of the initial backlight state for later.
493          */
494         if (pb->enable_gpio &&
495             gpiod_get_direction(pb->enable_gpio) != 0)
496                 gpiod_direction_output(pb->enable_gpio, 1);
497
498         pb->power_supply = devm_regulator_get(&pdev->dev, "power");
499         if (IS_ERR(pb->power_supply)) {
500                 ret = PTR_ERR(pb->power_supply);
501                 goto err_alloc;
502         }
503
504         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
505         if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !node) {
506                 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
507                 pb->legacy = true;
508                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
509         }
510
511         if (IS_ERR(pb->pwm)) {
512                 ret = PTR_ERR(pb->pwm);
513                 if (ret != -EPROBE_DEFER)
514                         dev_err(&pdev->dev, "unable to request PWM\n");
515                 goto err_alloc;
516         }
517
518         dev_dbg(&pdev->dev, "got pwm for backlight\n");
519
520         /* Sync up PWM state. */
521         pwm_init_state(pb->pwm, &state);
522
523         /*
524          * The DT case will set the pwm_period_ns field to 0 and store the
525          * period, parsed from the DT, in the PWM device. For the non-DT case,
526          * set the period from platform data if it has not already been set
527          * via the PWM lookup table.
528          */
529         if (!state.period && (data->pwm_period_ns > 0))
530                 state.period = data->pwm_period_ns;
531
532         ret = pwm_apply_state(pb->pwm, &state);
533         if (ret) {
534                 dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
535                         ret);
536                 goto err_alloc;
537         }
538
539         if (data->levels) {
540                 /*
541                  * For the DT case, only when brightness levels is defined
542                  * data->levels is filled. For the non-DT case, data->levels
543                  * can come from platform data, however is not usual.
544                  */
545                 for (i = 0; i <= data->max_brightness; i++) {
546                         if (data->levels[i] > pb->scale)
547                                 pb->scale = data->levels[i];
548
549                         pb->levels = data->levels;
550                 }
551         } else if (!data->max_brightness) {
552                 /*
553                  * If no brightness levels are provided and max_brightness is
554                  * not set, use the default brightness table. For the DT case,
555                  * max_brightness is set to 0 when brightness levels is not
556                  * specified. For the non-DT case, max_brightness is usually
557                  * set to some value.
558                  */
559
560                 /* Get the PWM period (in nanoseconds) */
561                 pwm_get_state(pb->pwm, &state);
562
563                 ret = pwm_backlight_brightness_default(&pdev->dev, data,
564                                                        state.period);
565                 if (ret < 0) {
566                         dev_err(&pdev->dev,
567                                 "failed to setup default brightness table\n");
568                         goto err_alloc;
569                 }
570
571                 for (i = 0; i <= data->max_brightness; i++) {
572                         if (data->levels[i] > pb->scale)
573                                 pb->scale = data->levels[i];
574
575                         pb->levels = data->levels;
576                 }
577         } else {
578                 /*
579                  * That only happens for the non-DT case, where platform data
580                  * sets the max_brightness value.
581                  */
582                 pb->scale = data->max_brightness;
583         }
584
585         pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
586
587         memset(&props, 0, sizeof(struct backlight_properties));
588         props.type = BACKLIGHT_RAW;
589         props.max_brightness = data->max_brightness;
590         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
591                                        &pwm_backlight_ops, &props);
592         if (IS_ERR(bl)) {
593                 dev_err(&pdev->dev, "failed to register backlight\n");
594                 ret = PTR_ERR(bl);
595                 if (pb->legacy)
596                         pwm_free(pb->pwm);
597                 goto err_alloc;
598         }
599
600         if (data->dft_brightness > data->max_brightness) {
601                 dev_warn(&pdev->dev,
602                          "invalid default brightness level: %u, using %u\n",
603                          data->dft_brightness, data->max_brightness);
604                 data->dft_brightness = data->max_brightness;
605         }
606
607         bl->props.brightness = data->dft_brightness;
608         bl->props.power = pwm_backlight_initial_power_state(pb);
609         backlight_update_status(bl);
610
611         platform_set_drvdata(pdev, bl);
612         return 0;
613
614 err_alloc:
615         if (data->exit)
616                 data->exit(&pdev->dev);
617         return ret;
618 }
619
620 static int pwm_backlight_remove(struct platform_device *pdev)
621 {
622         struct backlight_device *bl = platform_get_drvdata(pdev);
623         struct pwm_bl_data *pb = bl_get_data(bl);
624
625         backlight_device_unregister(bl);
626         pwm_backlight_power_off(pb);
627
628         if (pb->exit)
629                 pb->exit(&pdev->dev);
630         if (pb->legacy)
631                 pwm_free(pb->pwm);
632
633         return 0;
634 }
635
636 static void pwm_backlight_shutdown(struct platform_device *pdev)
637 {
638         struct backlight_device *bl = platform_get_drvdata(pdev);
639         struct pwm_bl_data *pb = bl_get_data(bl);
640
641         pwm_backlight_power_off(pb);
642 }
643
644 #ifdef CONFIG_PM_SLEEP
645 static int pwm_backlight_suspend(struct device *dev)
646 {
647         struct backlight_device *bl = dev_get_drvdata(dev);
648         struct pwm_bl_data *pb = bl_get_data(bl);
649
650         if (pb->notify)
651                 pb->notify(pb->dev, 0);
652
653         pwm_backlight_power_off(pb);
654
655         if (pb->notify_after)
656                 pb->notify_after(pb->dev, 0);
657
658         return 0;
659 }
660
661 static int pwm_backlight_resume(struct device *dev)
662 {
663         struct backlight_device *bl = dev_get_drvdata(dev);
664
665         backlight_update_status(bl);
666
667         return 0;
668 }
669 #endif
670
671 static const struct dev_pm_ops pwm_backlight_pm_ops = {
672 #ifdef CONFIG_PM_SLEEP
673         .suspend = pwm_backlight_suspend,
674         .resume = pwm_backlight_resume,
675         .poweroff = pwm_backlight_suspend,
676         .restore = pwm_backlight_resume,
677 #endif
678 };
679
680 static struct platform_driver pwm_backlight_driver = {
681         .driver         = {
682                 .name           = "pwm-backlight",
683                 .pm             = &pwm_backlight_pm_ops,
684                 .of_match_table = of_match_ptr(pwm_backlight_of_match),
685         },
686         .probe          = pwm_backlight_probe,
687         .remove         = pwm_backlight_remove,
688         .shutdown       = pwm_backlight_shutdown,
689 };
690
691 module_platform_driver(pwm_backlight_driver);
692
693 MODULE_DESCRIPTION("PWM based Backlight Driver");
694 MODULE_LICENSE("GPL v2");
695 MODULE_ALIAS("platform:pwm-backlight");