Re: [PATCH v3] HID: asus: support backlight on USB keyboards

[Benjamin Tissoires]

On Apr 06 2017 or thereabouts, Carlo Caione wrote:
> From: Carlo Caione <carlo@xxxxxxxxxxxx>
> 
> The latest USB keyboards shipped on several ASUS laptop models
> (including ROG laptop models such as GL702VMK) have the keyboards
> backlight controlled by the keyboard firmware.
> 
> The firmware implements at least 3 different commands:
> - Init command (to use when the system starts)
> - Configuration command (to get keyboard status/information)
> - Backlight level control (to change the level of the keyboard light)
> 
> With this patch we create the usual 'asus::kbd_backlight' led class
> entry to control the keyboard backlight.
> 
> Signed-off-by: Carlo Caione <carlo@xxxxxxxxxxxx>
> ---
> Changelog:
> 
> v2:
>  - Code refactoring
>  - s/sysfs/led class
>  - No error messages on kzalloc/kmemdup failing
>  - Fixed race condition when removing device
>  - Used devm_* when possible
>  - Added LEDS_CLASS dependency
> 
> v3:
>  - s/asus_kbd_get_report/asus_kbd_set_report
>  - Added cancel_work_sync()
>  - Return error from asus_kbd_register_leds()
>  - Do not leak drvdata->kbd_backlight on devm_led_classdev_register()
>    failure
>  - Coding style
> ---
>  drivers/hid/Kconfig    |   1 +
>  drivers/hid/hid-asus.c | 184 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 184 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index eb1846a..dec5f3e 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -136,6 +136,7 @@ config HID_APPLEIR
>  
>  config HID_ASUS
>  	tristate "Asus"
> +	depends on LEDS_CLASS
>  	---help---
>  	Support for Asus notebook built-in keyboard and touchpad via i2c, and
>  	the Asus Republic of Gamers laptop keyboard special keys.
> diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
> index bacba97..e78c7de 100644
> --- a/drivers/hid/hid-asus.c
> +++ b/drivers/hid/hid-asus.c
> @@ -40,8 +40,12 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
>  
>  #define FEATURE_REPORT_ID 0x0d
>  #define INPUT_REPORT_ID 0x5d
> +#define FEATURE_KBD_REPORT_ID 0x5a
>  
>  #define INPUT_REPORT_SIZE 28
> +#define FEATURE_KBD_REPORT_SIZE 16
> +
> +#define SUPPORT_KBD_BACKLIGHT BIT(0)
>  
>  #define MAX_CONTACTS 5
>  
> @@ -64,6 +68,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
>  #define QUIRK_SKIP_INPUT_MAPPING	BIT(2)
>  #define QUIRK_IS_MULTITOUCH		BIT(3)
>  #define QUIRK_NO_CONSUMER_USAGES	BIT(4)
> +#define QUIRK_USE_KBD_BACKLIGHT		BIT(5)
>  
>  #define I2C_KEYBOARD_QUIRKS			(QUIRK_FIX_NOTEBOOK_REPORT | \
>  						 QUIRK_NO_INIT_REPORTS | \
> @@ -74,9 +79,19 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
>  
>  #define TRKID_SGN       ((TRKID_MAX + 1) >> 1)
>  
> +struct asus_kbd_leds {
> +	struct led_classdev cdev;
> +	struct hid_device *hdev;
> +	struct work_struct work;
> +	unsigned int brightness;
> +	bool removed;
> +};
> +
>  struct asus_drvdata {
>  	unsigned long quirks;
>  	struct input_dev *input;
> +	struct asus_kbd_leds *kbd_backlight;
> +	bool enable_backlight;
>  };
>  
>  static void asus_report_contact_down(struct input_dev *input,
> @@ -171,6 +186,149 @@ static int asus_raw_event(struct hid_device *hdev,
>  	return 0;
>  }
>  
> +static int asus_kbd_set_report(struct hid_device *hdev, u8 *buf, size_t buf_size)
> +{
> +	unsigned char *dmabuf;
> +	int ret;
> +
> +	dmabuf = kmemdup(buf, buf_size, GFP_KERNEL);
> +	if (!dmabuf)
> +		return -ENOMEM;
> +
> +	ret = hid_hw_raw_request(hdev, FEATURE_KBD_REPORT_ID, dmabuf,
> +				 buf_size, HID_FEATURE_REPORT,
> +				 HID_REQ_SET_REPORT);
> +	kfree(dmabuf);
> +
> +	return ret;
> +}
> +
> +static int asus_kbd_init(struct hid_device *hdev)
> +{
> +	u8 buf[] = { FEATURE_KBD_REPORT_ID, 0x41, 0x53, 0x55, 0x53, 0x20, 0x54,
> +		     0x65, 0x63, 0x68, 0x2e, 0x49, 0x6e, 0x63, 0x2e, 0x00 };
> +	int ret;
> +
> +	ret = asus_kbd_set_report(hdev, buf, sizeof(buf));
> +	if (ret < 0)
> +		hid_err(hdev, "Asus failed to send init command: %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static int asus_kbd_get_functions(struct hid_device *hdev,
> +				  unsigned char *kbd_func)
> +{
> +	u8 buf[] = { FEATURE_KBD_REPORT_ID, 0x05, 0x20, 0x31, 0x00, 0x08 };
> +	u8 *readbuf;
> +	int ret;
> +
> +	ret = asus_kbd_set_report(hdev, buf, sizeof(buf));
> +	if (ret < 0) {
> +		hid_err(hdev, "Asus failed to send configuration command: %d\n", ret);
> +		return ret;
> +	}
> +
> +	readbuf = kzalloc(FEATURE_KBD_REPORT_SIZE, GFP_KERNEL);
> +	if (!readbuf)
> +		return -ENOMEM;
> +
> +	ret = hid_hw_raw_request(hdev, FEATURE_KBD_REPORT_ID, readbuf,
> +				 FEATURE_KBD_REPORT_SIZE, HID_FEATURE_REPORT,
> +				 HID_REQ_GET_REPORT);
> +	if (ret < 0) {
> +		hid_err(hdev, "Asus failed to request functions: %d\n", ret);
> +		kfree(readbuf);
> +		return ret;
> +	}
> +
> +	*kbd_func = readbuf[6];
> +
> +	kfree(readbuf);
> +	return ret;
> +}
> +
> +static void asus_kbd_backlight_set(struct led_classdev *led_cdev,
> +				   enum led_brightness brightness)
> +{
> +	struct asus_kbd_leds *led = container_of(led_cdev, struct asus_kbd_leds,
> +						 cdev);
> +	if (led->brightness == brightness)
> +		return;
> +
> +	led->brightness = brightness;
> +	schedule_work(&led->work);
> +}
> +
> +static enum led_brightness asus_kbd_backlight_get(struct led_classdev *led_cdev)
> +{
> +	struct asus_kbd_leds *led = container_of(led_cdev, struct asus_kbd_leds,
> +						 cdev);
> +
> +	return led->brightness;
> +}
> +
> +static void asus_kbd_backlight_work(struct work_struct *work)
> +{
> +	struct asus_kbd_leds *led = container_of(work, struct asus_kbd_leds, work);
> +	u8 buf[] = { FEATURE_KBD_REPORT_ID, 0xba, 0xc5, 0xc4, 0x00 };
> +	int ret;
> +
> +	if (led->removed)
> +		return;
> +
> +	buf[4] = led->brightness;
> +
> +	ret = asus_kbd_set_report(led->hdev, buf, sizeof(buf));
> +	if (ret < 0)
> +		hid_err(led->hdev, "Asus failed to set keyboard backlight: %d\n", ret);
> +}
> +
> +static int asus_kbd_register_leds(struct hid_device *hdev)
> +{
> +	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
> +	unsigned char kbd_func;
> +	int ret;
> +
> +	/* Initialize keyboard */
> +	ret = asus_kbd_init(hdev);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Get keyboard functions */
> +	ret = asus_kbd_get_functions(hdev, &kbd_func);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Check for backlight support */
> +	if (!(kbd_func & SUPPORT_KBD_BACKLIGHT))
> +		return -ENODEV;
> +
> +	drvdata->kbd_backlight = devm_kzalloc(&hdev->dev,
> +					      sizeof(struct asus_kbd_leds),
> +					      GFP_KERNEL);
> +	if (!drvdata->kbd_backlight)
> +		return -ENOMEM;
> +
> +	drvdata->kbd_backlight->removed = false;
> +	drvdata->kbd_backlight->brightness = 0;
> +	drvdata->kbd_backlight->hdev = hdev;
> +	drvdata->kbd_backlight->cdev.name = "asus::kbd_backlight";
> +	drvdata->kbd_backlight->cdev.max_brightness = 3;
> +	drvdata->kbd_backlight->cdev.brightness_set = asus_kbd_backlight_set;
> +	drvdata->kbd_backlight->cdev.brightness_get = asus_kbd_backlight_get;
> +	INIT_WORK(&drvdata->kbd_backlight->work, asus_kbd_backlight_work);
> +
> +	ret = devm_led_classdev_register(&hdev->dev, &drvdata->kbd_backlight->cdev);
> +	if (ret < 0) {
> +		/* No need to have this still around */
> +		devm_kfree(&hdev->dev, drvdata->kbd_backlight);
> +		cancel_work_sync(&drvdata->kbd_backlight->work);

Small nitpick, you don't need to call cancel_work_sync() here, nobody
could have called a worker. But OTOH, it doesn't hurt.

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>

Cheers,
Benjamin

> +	}
> +
> +	return ret;
> +}
> +
>  static int asus_input_configured(struct hid_device *hdev, struct hid_input *hi)
>  {
>  	struct input_dev *input = hi->input;
> @@ -198,6 +356,9 @@ static int asus_input_configured(struct hid_device *hdev, struct hid_input *hi)
>  
>  	drvdata->input = input;
>  
> +	if (drvdata->enable_backlight && asus_kbd_register_leds(hdev))
> +		hid_warn(hdev, "Failed to initialize backlight.\n");
> +
>  	return 0;
>  }
>  
> @@ -248,6 +409,16 @@ static int asus_input_mapping(struct hid_device *hdev,
>  			 * as some make the keyboard appear as a pointer device. */
>  			return -1;
>  		}
> +
> +		/*
> +		 * Check and enable backlight only on devices with UsagePage ==
> +		 * 0xff31 to avoid initializing the keyboard firmware multiple
> +		 * times on devices with multiple HID descriptors but same
> +		 * PID/VID.
> +		 */
> +		if (drvdata->quirks & QUIRK_USE_KBD_BACKLIGHT)
> +			drvdata->enable_backlight = true;
> +
>  		return 1;
>  	}
>  
> @@ -358,6 +529,16 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  	return ret;
>  }
>  
> +static void asus_remove(struct hid_device *hdev)
> +{
> +	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
> +
> +	if (drvdata->kbd_backlight) {
> +		drvdata->kbd_backlight->removed = true;
> +		cancel_work_sync(&drvdata->kbd_backlight->work);
> +	}
> +}
> +
>  static __u8 *asus_report_fixup(struct hid_device *hdev, __u8 *rdesc,
>  		unsigned int *rsize)
>  {
> @@ -379,7 +560,7 @@ static const struct hid_device_id asus_devices[] = {
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK,
>  		USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD1) },
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK,
> -		USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD2) },
> +		USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD2), QUIRK_USE_KBD_BACKLIGHT },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(hid, asus_devices);
> @@ -389,6 +570,7 @@ static struct hid_driver asus_driver = {
>  	.id_table		= asus_devices,
>  	.report_fixup		= asus_report_fixup,
>  	.probe                  = asus_probe,
> +	.remove			= asus_remove,
>  	.input_mapping          = asus_input_mapping,
>  	.input_configured       = asus_input_configured,
>  #ifdef CONFIG_PM
> -- 
> 2.9.3
>