Re: [PATCH v2 1/3] HID: apple: Add support for keyboard backlight on certain T2 Macs.

[Aditya Garg]

> On 24-Jan-2022, at 8:38 PM, Aditya Garg <gargaditya08@xxxxxxxx> wrote:
> 
> From: Paul Pawlowski <paul@xxxxxxxx>
> 
> This patch introduces the requisite plumbing for supporting keyboard
> backlight on T2-attached, USB exposed models. The quirk mechanism was
> used to reuse the existing hid-apple driver.
> 
> Signed-off-by: Paul Pawlowski <paul@xxxxxxxx>
> Signed-off-by: Aun-Ali Zaidi <admin@xxxxxxxxxx>
> Signed-off-by: Aditya Garg <gargaditya08@xxxxxxxx>
> ---
> drivers/hid/hid-apple.c | 125 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 125 insertions(+)
> 
> diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
> index 24802a4a6..c22d445a9 100644
> --- a/drivers/hid/hid-apple.c
> +++ b/drivers/hid/hid-apple.c
> @@ -7,6 +7,7 @@
>  *  Copyright (c) 2005 Michael Haboustak <mike-@xxxxxxxxxxxx> for Concept2, Inc
>  *  Copyright (c) 2006-2007 Jiri Kosina
>  *  Copyright (c) 2008 Jiri Slaby <jirislaby@xxxxxxxxx>
> + *  Copyright (c) 2019 Paul Pawlowski <paul@xxxxxxxx>
>  */
> 
> /*
> @@ -33,6 +34,7 @@
> /* BIT(7) reserved, was: APPLE_IGNORE_HIDINPUT */
> #define APPLE_NUMLOCK_EMULATION	BIT(8)
> #define APPLE_RDESC_BATTERY	BIT(9)
> +#define APPLE_BACKLIGHT_CTL	0x0200
Jiri, should it be BIT(10)? 0x0200 is BIT(9) if I ain’t wrong.
> 
> #define APPLE_FLAG_FKEY		0x01
> 
> @@ -61,6 +63,12 @@ MODULE_PARM_DESC(swap_fn_leftctrl, "Swap the Fn and left Control keys. "
> 		"(For people who want to keep PC keyboard muscle memory. "
> 		"[0] = as-is, Mac layout, 1 = swapped, PC layout)");
> 
> +struct apple_sc_backlight {
> +	struct led_classdev cdev;
> +	struct hid_device *hdev;
> +	unsigned short backlight_off, backlight_on_min, backlight_on_max;
> +};
> +
> struct apple_sc {
> 	struct hid_device *hdev;
> 	unsigned long quirks;
> @@ -68,6 +76,7 @@ struct apple_sc {
> 	unsigned int fn_found;
> 	DECLARE_BITMAP(pressed_numlock, KEY_CNT);
> 	struct timer_list battery_timer;
> +	struct apple_sc_backlight *backlight;
> };
> 
> struct apple_key_translation {
> @@ -76,6 +85,20 @@ struct apple_key_translation {
> 	u8 flags;
> };
> 
> +struct apple_backlight_config_report {
> +	u8 report_id;
> +	u8 version;
> +	u16 backlight_off, backlight_on_min, backlight_on_max;
> +};
> +
> +struct apple_backlight_set_report {
> +	u8 report_id;
> +	u8 version;
> +	u16 backlight;
> +	u16 rate;
> +};
> +
> +
> static const struct apple_key_translation apple2021_fn_keys[] = {
> 	{ KEY_BACKSPACE, KEY_DELETE },
> 	{ KEY_ENTER,	KEY_INSERT },
> @@ -530,6 +553,105 @@ static int apple_input_configured(struct hid_device *hdev,
> 	return 0;
> }
> 
> +static bool apple_backlight_check_support(struct hid_device *hdev)
> +{
> +	int i;
> +	unsigned int hid;
> +	struct hid_report *report;
> +
> +	list_for_each_entry(report, &hdev->report_enum[HID_INPUT_REPORT].report_list, list) {
> +		for (i = 0; i < report->maxfield; i++) {
> +			hid = report->field[i]->usage->hid;
> +			if ((hid & HID_USAGE_PAGE) == HID_UP_MSVENDOR && (hid & HID_USAGE) == 0xf)
> +				return true;
> +		}
> +	}
> +
> +	return false;
> +}
> +
> +static int apple_backlight_set(struct hid_device *hdev, u16 value, u16 rate)
> +{
> +	int ret = 0;
> +	struct apple_backlight_set_report *rep;
> +
> +	rep = kmalloc(sizeof(*rep), GFP_KERNEL);
> +	if (rep == NULL)
> +		return -ENOMEM;
> +
> +	rep->report_id = 0xB0;
> +	rep->version = 1;
> +	rep->backlight = value;
> +	rep->rate = rate;
> +
> +	ret = hid_hw_raw_request(hdev, 0xB0u, (u8 *) rep, sizeof(*rep),
> +				 HID_OUTPUT_REPORT, HID_REQ_SET_REPORT);
> +
> +	kfree(rep);
> +	return ret;
> +}
> +
> +static int apple_backlight_led_set(struct led_classdev *led_cdev,
> +	enum led_brightness brightness)
> +{
> +	struct apple_sc_backlight *backlight = container_of(led_cdev,
> +							    struct apple_sc_backlight, cdev);
> +
> +	return apple_backlight_set(backlight->hdev, brightness, 0);
> +}
> +
> +static int apple_backlight_init(struct hid_device *hdev)
> +{
> +	int ret;
> +	struct apple_sc *asc = hid_get_drvdata(hdev);
> +	struct apple_backlight_config_report *rep;
> +
> +	if (!apple_backlight_check_support(hdev))
> +		return -EINVAL;
> +
> +	rep = kmalloc(0x200, GFP_KERNEL);
> +	if (rep == NULL)
> +		return -ENOMEM;
> +
> +	ret = hid_hw_raw_request(hdev, 0xBFu, (u8 *) rep, sizeof(*rep),
> +				 HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
> +	if (ret < 0) {
> +		hid_err(hdev, "backlight request failed: %d\n", ret);
> +		goto cleanup_and_exit;
> +	}
> +	if (ret < 8 || rep->version != 1) {
> +		hid_err(hdev, "backlight config struct: bad version %i\n", rep->version);
> +		ret = -EINVAL;
> +		goto cleanup_and_exit;
> +	}
> +
> +	hid_dbg(hdev, "backlight config: off=%u, on_min=%u, on_max=%u\n",
> +		rep->backlight_off, rep->backlight_on_min, rep->backlight_on_max);
> +
> +	asc->backlight = devm_kzalloc(&hdev->dev, sizeof(*asc->backlight), GFP_KERNEL);
> +	if (!asc->backlight) {
> +		ret = -ENOMEM;
> +		goto cleanup_and_exit;
> +	}
> +
> +	asc->backlight->hdev = hdev;
> +	asc->backlight->cdev.name = "apple::kbd_backlight";
> +	asc->backlight->cdev.max_brightness = rep->backlight_on_max;
> +	asc->backlight->cdev.brightness_set_blocking = apple_backlight_led_set;
> +
> +	ret = apple_backlight_set(hdev, 0, 0);
> +	if (ret < 0) {
> +		hid_err(hdev, "backlight set request failed: %d\n", ret);
> +		goto cleanup_and_exit;
> +	}
> +
> +	ret = devm_led_classdev_register(&hdev->dev, &asc->backlight->cdev);
> +
> +cleanup_and_exit:
> +	kfree(rep);
> +	return ret;
> +}
> +
> static int apple_probe(struct hid_device *hdev,
> 		const struct hid_device_id *id)
> {
> @@ -565,6 +687,9 @@ static int apple_probe(struct hid_device *hdev,
> 		  jiffies + msecs_to_jiffies(APPLE_BATTERY_TIMEOUT_MS));
> 	apple_fetch_battery(hdev);
> 
> +	if (quirks & APPLE_BACKLIGHT_CTL)
> +		apple_backlight_init(hdev);
> +
> 	return 0;
> }
> 
> -- 
> 2.25.1
> 
>