HID: google: add support tablet mode switch for Whiskers
authorDmitry Torokhov <dtor@chromium.org>
Fri, 5 Oct 2018 18:41:14 +0000 (11:41 -0700)
committerJiri Kosina <jkosina@suse.cz>
Tue, 9 Oct 2018 08:40:55 +0000 (10:40 +0200)
Whiskers is a foldable base, and thus requires combining "base presence"
signal coming from EC with base state signal (folded/unfolded) coming
from USB/HID interface to produce proper SW_TABLET_MODE event.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
drivers/hid/hid-google-hammer.c

index 6bf4da7..de3e7d0 100644 (file)
  * any later version.
  */
 
+#include <linux/acpi.h>
 #include <linux/hid.h>
 #include <linux/leds.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
 #include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeup.h>
+#include <asm/unaligned.h>
 
 #include "hid-ids.h"
 
-#define MAX_BRIGHTNESS 100
+/*
+ * C(hrome)B(ase)A(ttached)S(witch) - switch exported by Chrome EC and reporting
+ * state of the "Whiskers" base - attached or detached. Whiskers USB device also
+ * reports position of the keyboard - folded or not. Combining base state and
+ * position allows us to generate proper "Tablet mode" events.
+ */
+struct cbas_ec {
+       struct device *dev;     /* The platform device (EC) */
+       struct input_dev *input;
+       bool base_present;
+       struct notifier_block notifier;
+};
 
-/* HID usage for keyboard backlight (Alphanumeric display brightness) */
-#define HID_AD_BRIGHTNESS 0x00140046
+static struct cbas_ec cbas_ec;
+static DEFINE_SPINLOCK(cbas_ec_lock);
+static DEFINE_MUTEX(cbas_ec_reglock);
+
+static bool cbas_parse_base_state(const void *data)
+{
+       u32 switches = get_unaligned_le32(data);
+
+       return !!(switches & BIT(EC_MKBP_BASE_ATTACHED));
+}
+
+static int cbas_ec_query_base(struct cros_ec_device *ec_dev, bool get_state,
+                                 bool *state)
+{
+       struct ec_params_mkbp_info *params;
+       struct cros_ec_command *msg;
+       int ret;
+
+       msg = kzalloc(sizeof(*msg) + max(sizeof(u32), sizeof(*params)),
+                     GFP_KERNEL);
+       if (!msg)
+               return -ENOMEM;
+
+       msg->command = EC_CMD_MKBP_INFO;
+       msg->version = 1;
+       msg->outsize = sizeof(*params);
+       msg->insize = sizeof(u32);
+       params = (struct ec_params_mkbp_info *)msg->data;
+       params->info_type = get_state ?
+               EC_MKBP_INFO_CURRENT : EC_MKBP_INFO_SUPPORTED;
+       params->event_type = EC_MKBP_EVENT_SWITCH;
+
+       ret = cros_ec_cmd_xfer_status(ec_dev, msg);
+       if (ret >= 0) {
+               if (ret != sizeof(u32)) {
+                       dev_warn(ec_dev->dev, "wrong result size: %d != %zu\n",
+                                ret, sizeof(u32));
+                       ret = -EPROTO;
+               } else {
+                       *state = cbas_parse_base_state(msg->data);
+                       ret = 0;
+               }
+       }
+
+       kfree(msg);
+
+       return ret;
+}
+
+static int cbas_ec_notify(struct notifier_block *nb,
+                             unsigned long queued_during_suspend,
+                             void *_notify)
+{
+       struct cros_ec_device *ec = _notify;
+       unsigned long flags;
+       bool base_present;
+
+       if (ec->event_data.event_type == EC_MKBP_EVENT_SWITCH) {
+               base_present = cbas_parse_base_state(
+                                       &ec->event_data.data.switches);
+               dev_dbg(cbas_ec.dev,
+                       "%s: base: %d\n", __func__, base_present);
+
+               if (device_may_wakeup(cbas_ec.dev) ||
+                   !queued_during_suspend) {
+
+                       pm_wakeup_event(cbas_ec.dev, 0);
+
+                       spin_lock_irqsave(&cbas_ec_lock, flags);
+
+                       /*
+                        * While input layer dedupes the events, we do not want
+                        * to disrupt the state reported by the base by
+                        * overriding it with state reported by the LID. Only
+                        * report changes, as we assume that on attach the base
+                        * is not folded.
+                        */
+                       if (base_present != cbas_ec.base_present) {
+                               input_report_switch(cbas_ec.input,
+                                                   SW_TABLET_MODE,
+                                                   !base_present);
+                               input_sync(cbas_ec.input);
+                               cbas_ec.base_present = base_present;
+                       }
+
+                       spin_unlock_irqrestore(&cbas_ec_lock, flags);
+               }
+       }
+
+       return NOTIFY_OK;
+}
+
+static __maybe_unused int cbas_ec_resume(struct device *dev)
+{
+       struct cros_ec_device *ec = dev_get_drvdata(dev->parent);
+       bool base_present;
+       int error;
+
+       error = cbas_ec_query_base(ec, true, &base_present);
+       if (error) {
+               dev_warn(dev, "failed to fetch base state on resume: %d\n",
+                        error);
+       } else {
+               spin_lock_irq(&cbas_ec_lock);
+
+               cbas_ec.base_present = base_present;
+
+               /*
+                * Only report if base is disconnected. If base is connected,
+                * it will resend its state on resume, and we'll update it
+                * in hammer_event().
+                */
+               if (!cbas_ec.base_present) {
+                       input_report_switch(cbas_ec.input, SW_TABLET_MODE, 1);
+                       input_sync(cbas_ec.input);
+               }
+
+               spin_unlock_irq(&cbas_ec_lock);
+       }
+
+       return 0;
+}
+
+static const SIMPLE_DEV_PM_OPS(cbas_ec_pm_ops, NULL, cbas_ec_resume);
+
+static void cbas_ec_set_input(struct input_dev *input)
+{
+       /* Take the lock so hammer_event() does not race with us here */
+       spin_lock_irq(&cbas_ec_lock);
+       cbas_ec.input = input;
+       spin_unlock_irq(&cbas_ec_lock);
+}
+
+static int __cbas_ec_probe(struct platform_device *pdev)
+{
+       struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+       struct input_dev *input;
+       bool base_supported;
+       int error;
+
+       error = cbas_ec_query_base(ec, false, &base_supported);
+       if (error)
+               return error;
+
+       if (!base_supported)
+               return -ENXIO;
+
+       input = devm_input_allocate_device(&pdev->dev);
+       if (!input)
+               return -ENOMEM;
+
+       input->name = "Whiskers Tablet Mode Switch";
+       input->id.bustype = BUS_HOST;
+
+       input_set_capability(input, EV_SW, SW_TABLET_MODE);
+
+       error = input_register_device(input);
+       if (error) {
+               dev_err(&pdev->dev, "cannot register input device: %d\n",
+                       error);
+               return error;
+       }
+
+       /* Seed the state */
+       error = cbas_ec_query_base(ec, true, &cbas_ec.base_present);
+       if (error) {
+               dev_err(&pdev->dev, "cannot query base state: %d\n", error);
+               return error;
+       }
+
+       input_report_switch(input, SW_TABLET_MODE, !cbas_ec.base_present);
+
+       cbas_ec_set_input(input);
+
+       cbas_ec.dev = &pdev->dev;
+       cbas_ec.notifier.notifier_call = cbas_ec_notify;
+       error = blocking_notifier_chain_register(&ec->event_notifier,
+                                                &cbas_ec.notifier);
+       if (error) {
+               dev_err(&pdev->dev, "cannot register notifier: %d\n", error);
+               cbas_ec_set_input(NULL);
+               return error;
+       }
+
+       device_init_wakeup(&pdev->dev, true);
+       return 0;
+}
+
+static int cbas_ec_probe(struct platform_device *pdev)
+{
+       int retval;
+
+       mutex_lock(&cbas_ec_reglock);
+
+       if (cbas_ec.input) {
+               retval = -EBUSY;
+               goto out;
+       }
+
+       retval = __cbas_ec_probe(pdev);
+
+out:
+       mutex_unlock(&cbas_ec_reglock);
+       return retval;
+}
+
+static int cbas_ec_remove(struct platform_device *pdev)
+{
+       struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+
+       mutex_lock(&cbas_ec_reglock);
+
+       blocking_notifier_chain_unregister(&ec->event_notifier,
+                                          &cbas_ec.notifier);
+       cbas_ec_set_input(NULL);
+
+       mutex_unlock(&cbas_ec_reglock);
+       return 0;
+}
+
+static const struct acpi_device_id cbas_ec_acpi_ids[] = {
+       { "GOOG000B", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(acpi, cbas_ec_acpi_ids);
+
+static struct platform_driver cbas_ec_driver = {
+       .probe = cbas_ec_probe,
+       .remove = cbas_ec_remove,
+       .driver = {
+               .name = "cbas_ec",
+               .acpi_match_table = ACPI_PTR(cbas_ec_acpi_ids),
+               .pm = &cbas_ec_pm_ops,
+       },
+};
+
+#define MAX_BRIGHTNESS 100
 
 struct hammer_kbd_leds {
        struct led_classdev cdev;
@@ -90,33 +342,130 @@ static int hammer_register_leds(struct hid_device *hdev)
        return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
 }
 
-static int hammer_input_configured(struct hid_device *hdev,
-                                  struct hid_input *hi)
+#define HID_UP_GOOGLEVENDOR    0xffd10000
+#define HID_VD_KBD_FOLDED      0x00000019
+#define WHISKERS_KBD_FOLDED    (HID_UP_GOOGLEVENDOR | HID_VD_KBD_FOLDED)
+
+/* HID usage for keyboard backlight (Alphanumeric display brightness) */
+#define HID_AD_BRIGHTNESS      0x00140046
+
+static int hammer_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+                               struct hid_field *field,
+                               struct hid_usage *usage,
+                               unsigned long **bit, int *max)
 {
-       struct list_head *report_list =
-               &hdev->report_enum[HID_OUTPUT_REPORT].report_list;
+       if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+           usage->hid == WHISKERS_KBD_FOLDED) {
+               /*
+                * We do not want to have this usage mapped as it will get
+                * mixed in with "base attached" signal and delivered over
+                * separate input device for tablet switch mode.
+                */
+               return -1;
+       }
+
+       return 0;
+}
+
+static int hammer_event(struct hid_device *hid, struct hid_field *field,
+                       struct hid_usage *usage, __s32 value)
+{
+       unsigned long flags;
+
+       if (hid->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+           usage->hid == WHISKERS_KBD_FOLDED) {
+               spin_lock_irqsave(&cbas_ec_lock, flags);
+
+               hid_dbg(hid, "%s: base: %d, folded: %d\n", __func__,
+                       cbas_ec.base_present, value);
+
+               /*
+                * We should not get event if base is detached, but in case
+                * we happen to service HID and EC notifications out of order
+                * let's still check the "base present" flag.
+                */
+               if (cbas_ec.input && cbas_ec.base_present) {
+                       input_report_switch(cbas_ec.input,
+                                           SW_TABLET_MODE, value);
+                       input_sync(cbas_ec.input);
+               }
+
+               spin_unlock_irqrestore(&cbas_ec_lock, flags);
+               return 1; /* We handled this event */
+       }
+
+       return 0;
+}
+
+static bool hammer_is_keyboard_interface(struct hid_device *hdev)
+{
+       struct hid_report_enum *re = &hdev->report_enum[HID_INPUT_REPORT];
        struct hid_report *report;
 
-       if (list_empty(report_list))
-               return 0;
+       list_for_each_entry(report, &re->report_list, list)
+               if (report->application == HID_GD_KEYBOARD)
+                       return true;
 
-       report = list_first_entry(report_list, struct hid_report, list);
+       return false;
+}
+
+static bool hammer_has_backlight_control(struct hid_device *hdev)
+{
+       struct hid_report_enum *re = &hdev->report_enum[HID_OUTPUT_REPORT];
+       struct hid_report *report;
+       int i, j;
 
-       if (report->maxfield == 1 &&
-           report->field[0]->application == HID_GD_KEYBOARD &&
-           report->field[0]->maxusage == 1 &&
-           report->field[0]->usage[0].hid == HID_AD_BRIGHTNESS) {
-               int err = hammer_register_leds(hdev);
+       list_for_each_entry(report, &re->report_list, list) {
+               if (report->application != HID_GD_KEYBOARD)
+                       continue;
 
-               if (err)
+               for (i = 0; i < report->maxfield; i++) {
+                       struct hid_field *field = report->field[i];
+
+                       for (j = 0; j < field->maxusage; j++)
+                               if (field->usage[j].hid == HID_AD_BRIGHTNESS)
+                                       return true;
+               }
+       }
+
+       return false;
+}
+
+static int hammer_probe(struct hid_device *hdev,
+                       const struct hid_device_id *id)
+{
+       int error;
+
+       /*
+        * We always want to poll for, and handle tablet mode events from
+        * Whiskers, even when nobody has opened the input device. This also
+        * prevents the hid core from dropping early tablet mode events from
+        * the device.
+        */
+       if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+                       hammer_is_keyboard_interface(hdev))
+               hdev->quirks |= HID_QUIRK_ALWAYS_POLL;
+
+       error = hid_parse(hdev);
+       if (error)
+               return error;
+
+       error = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+       if (error)
+               return error;
+
+       if (hammer_has_backlight_control(hdev)) {
+               error = hammer_register_leds(hdev);
+               if (error)
                        hid_warn(hdev,
                                "Failed to register keyboard backlight: %d\n",
-                               err);
+                               error);
        }
 
        return 0;
 }
 
+
 static const struct hid_device_id hammer_devices[] = {
        { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
                     USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER) },
@@ -133,8 +482,34 @@ MODULE_DEVICE_TABLE(hid, hammer_devices);
 static struct hid_driver hammer_driver = {
        .name = "hammer",
        .id_table = hammer_devices,
-       .input_configured = hammer_input_configured,
+       .probe = hammer_probe,
+       .input_mapping = hammer_input_mapping,
+       .event = hammer_event,
 };
-module_hid_driver(hammer_driver);
+
+static int __init hammer_init(void)
+{
+       int error;
+
+       error = platform_driver_register(&cbas_ec_driver);
+       if (error)
+               return error;
+
+       error = hid_register_driver(&hammer_driver);
+       if (error) {
+               platform_driver_unregister(&cbas_ec_driver);
+               return error;
+       }
+
+       return 0;
+}
+module_init(hammer_init);
+
+static void __exit hammer_exit(void)
+{
+       hid_unregister_driver(&hammer_driver);
+       platform_driver_unregister(&cbas_ec_driver);
+}
+module_exit(hammer_exit);
 
 MODULE_LICENSE("GPL");