[PATCH v6 0/1] platform/x86: asus-wmi: add support for ASUS screenpad

[PATCH v6 0/1] platform/x86: asus-wmi: add support for ASUS screenpad

[Luke D. Jones]

Add support for the WMI methods used to turn off and adjust the
brightness of the secondary "screenpad" device found on some high-end
ASUS laptops like the GX650P series and others.

Changelog:
- V6
  - Move bulk of cover letter in to commit message
  - Add define for ASUS_SCREENPAD_BRIGHT_DEFAULT to be used on boot
  - Remove the use of max() in update_screenpad_bl_status()
  - Previous: https://lore.kernel.org/all/20230827232358.80512-1-luke@ljones.dev/
- V5
  - Add minimum brightness to prevent screen from becoming invisible
  - Previous: https://lore.kernel.org/all/20230630041743.911303-1-luke@ljones.dev/
- V4
  - Fix a null dereference that happened if the display was powered off and dev struct uninitialised yet
  - Previous: https://lore.kernel.org/all/20230620030033.55033-1-luke@ljones.dev/
- V3
  - Refactor error handling in all functions
- V2
  - Complete refactor to use as a backlight device

Luke D. Jones (1):
  platform/x86: asus-wmi: add support for ASUS screenpad

 drivers/platform/x86/asus-wmi.c            | 133 +++++++++++++++++++++
 drivers/platform/x86/asus-wmi.h            |   1 +
 include/linux/platform_data/x86/asus-wmi.h |   4 +
 3 files changed, 138 insertions(+)

-- 
2.41.0

[PATCH v6 1/1] platform/x86: asus-wmi: add support for ASUS screenpad

[Luke D. Jones]

Add support for the WMI methods used to turn off and adjust the
brightness of the secondary "screenpad" device found on some high-end
ASUS laptops like the GX650P series and others.

There are some small quirks with this device when considering only the
raw WMI methods:
1. The Off method can only switch the device off
2. Changing the brightness turns the device back on
3. To turn the device back on the brightness must be > 1
4. When the device is off the brightness can't be changed (so it is
   stored by the driver if device is off).
5. Booting with a value of 0 brightness (retained by bios) means the bios
   will set a value of >0 <15
6. When the device is off it is "unplugged"

asus_wmi sets the minimum brightness as 20 in general use, and 60 for
booting with values <= min.

The ACPI methods are used in a new backlight device named asus_screenpad.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
---
 drivers/platform/x86/asus-wmi.c            | 133 +++++++++++++++++++++
 drivers/platform/x86/asus-wmi.h            |   1 +
 include/linux/platform_data/x86/asus-wmi.h |   4 +
 3 files changed, 138 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index f54178d6f780..0b13be703856 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -25,6 +25,7 @@
 #include <linux/input/sparse-keymap.h>
 #include <linux/kernel.h>
 #include <linux/leds.h>
+#include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/pci_hotplug.h>
@@ -127,6 +128,10 @@ module_param(fnlock_default, bool, 0444);
 #define NVIDIA_TEMP_MIN		75
 #define NVIDIA_TEMP_MAX		87
 
+#define ASUS_SCREENPAD_BRIGHT_MIN 20
+#define ASUS_SCREENPAD_BRIGHT_MAX 255
+#define ASUS_SCREENPAD_BRIGHT_DEFAULT 60
+
 static const char * const ashs_ids[] = { "ATK4001", "ATK4002", NULL };
 
 static int throttle_thermal_policy_write(struct asus_wmi *);
@@ -212,6 +217,7 @@ struct asus_wmi {
 
 	struct input_dev *inputdev;
 	struct backlight_device *backlight_device;
+	struct backlight_device *screenpad_backlight_device;
 	struct platform_device *platform_device;
 
 	struct led_classdev wlan_led;
@@ -3776,6 +3782,124 @@ static int is_display_toggle(int code)
 	return 0;
 }
 
+/* Screenpad backlight *******************************************************/
+
+static int read_screenpad_backlight_power(struct asus_wmi *asus)
+{
+	int ret;
+
+	ret = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_SCREENPAD_POWER);
+	if (ret < 0)
+		return ret;
+	/* 1 == powered */
+	return ret ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
+}
+
+static int read_screenpad_brightness(struct backlight_device *bd)
+{
+	struct asus_wmi *asus = bl_get_data(bd);
+	u32 retval;
+	int err;
+
+	err = read_screenpad_backlight_power(asus);
+	if (err < 0)
+		return err;
+	/* The device brightness can only be read if powered, so return stored */
+	if (err == FB_BLANK_POWERDOWN)
+		return asus->driver->screenpad_brightness - ASUS_SCREENPAD_BRIGHT_MIN;
+
+	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT, &retval);
+	if (err < 0)
+		return err;
+
+	return (retval & ASUS_WMI_DSTS_BRIGHTNESS_MASK) - ASUS_SCREENPAD_BRIGHT_MIN;
+}
+
+static int update_screenpad_bl_status(struct backlight_device *bd)
+{
+	struct asus_wmi *asus = bl_get_data(bd);
+	int power, err = 0;
+	u32 ctrl_param;
+
+	power = read_screenpad_backlight_power(asus);
+	if (power < 0)
+		return power;
+
+	if (bd->props.power != power) {
+		if (power != FB_BLANK_UNBLANK) {
+			/* Only brightness > 0 can power it back on */
+			ctrl_param = asus->driver->screenpad_brightness - ASUS_SCREENPAD_BRIGHT_MIN;
+			err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_LIGHT,
+						    ctrl_param, NULL);
+		} else {
+			err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_POWER, 0, NULL);
+		}
+	} else if (power == FB_BLANK_UNBLANK) {
+		/* Only set brightness if powered on or we get invalid/unsync state */
+		ctrl_param = bd->props.brightness + ASUS_SCREENPAD_BRIGHT_MIN;
+		err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_LIGHT, ctrl_param, NULL);
+	}
+
+	/* Ensure brightness is stored to turn back on with */
+	if (err == 0)
+		asus->driver->screenpad_brightness = bd->props.brightness + ASUS_SCREENPAD_BRIGHT_MIN;
+
+	return err;
+}
+
+static const struct backlight_ops asus_screenpad_bl_ops = {
+	.get_brightness = read_screenpad_brightness,
+	.update_status = update_screenpad_bl_status,
+	.options = BL_CORE_SUSPENDRESUME,
+};
+
+static int asus_screenpad_init(struct asus_wmi *asus)
+{
+	struct backlight_device *bd;
+	struct backlight_properties props;
+	int err, power;
+	int brightness = 0;
+
+	power = read_screenpad_backlight_power(asus);
+	if (power < 0)
+		return power;
+
+	if (power != FB_BLANK_POWERDOWN) {
+		err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT, &brightness);
+		if (err < 0)
+			return err;
+	}
+	/* default to an acceptable min brightness on boot if too low */
+	if (brightness < ASUS_SCREENPAD_BRIGHT_MIN)
+		brightness = ASUS_SCREENPAD_BRIGHT_DEFAULT;
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW; /* ensure this bd is last to be picked */
+	props.max_brightness = ASUS_SCREENPAD_BRIGHT_MAX - ASUS_SCREENPAD_BRIGHT_MIN;
+	bd = backlight_device_register("asus_screenpad",
+				       &asus->platform_device->dev, asus,
+				       &asus_screenpad_bl_ops, &props);
+	if (IS_ERR(bd)) {
+		pr_err("Could not register backlight device\n");
+		return PTR_ERR(bd);
+	}
+
+	asus->screenpad_backlight_device = bd;
+	asus->driver->screenpad_brightness = brightness;
+	bd->props.brightness = brightness;
+	bd->props.power = power;
+	backlight_update_status(bd);
+
+	return 0;
+}
+
+static void asus_screenpad_exit(struct asus_wmi *asus)
+{
+	backlight_device_unregister(asus->screenpad_backlight_device);
+
+	asus->screenpad_backlight_device = NULL;
+}
+
 /* Fn-lock ********************************************************************/
 
 static bool asus_wmi_has_fnlock_key(struct asus_wmi *asus)
@@ -4431,6 +4555,12 @@ static int asus_wmi_add(struct platform_device *pdev)
 	} else if (asus->driver->quirks->wmi_backlight_set_devstate)
 		err = asus_wmi_set_devstate(ASUS_WMI_DEVID_BACKLIGHT, 2, NULL);
 
+	if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT)) {
+		err = asus_screenpad_init(asus);
+		if (err && err != -ENODEV)
+			goto fail_screenpad;
+	}
+
 	if (asus_wmi_has_fnlock_key(asus)) {
 		asus->fnlock_locked = fnlock_default;
 		asus_wmi_fnlock_update(asus);
@@ -4454,6 +4584,8 @@ static int asus_wmi_add(struct platform_device *pdev)
 	asus_wmi_backlight_exit(asus);
 fail_backlight:
 	asus_wmi_rfkill_exit(asus);
+fail_screenpad:
+	asus_screenpad_exit(asus);
 fail_rfkill:
 	asus_wmi_led_exit(asus);
 fail_leds:
@@ -4480,6 +4612,7 @@ static int asus_wmi_remove(struct platform_device *device)
 	asus = platform_get_drvdata(device);
 	wmi_remove_notify_handler(asus->driver->event_guid);
 	asus_wmi_backlight_exit(asus);
+	asus_screenpad_exit(asus);
 	asus_wmi_input_exit(asus);
 	asus_wmi_led_exit(asus);
 	asus_wmi_rfkill_exit(asus);
diff --git a/drivers/platform/x86/asus-wmi.h b/drivers/platform/x86/asus-wmi.h
index a478ebfd34df..5fbdd0eafa02 100644
--- a/drivers/platform/x86/asus-wmi.h
+++ b/drivers/platform/x86/asus-wmi.h
@@ -57,6 +57,7 @@ struct quirk_entry {
 struct asus_wmi_driver {
 	int			brightness;
 	int			panel_power;
+	int			screenpad_brightness;
 	int			wlan_ctrl_by_user;
 
 	const char		*name;
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index 16e99a1c37fc..63e630276499 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -58,6 +58,10 @@
 #define ASUS_WMI_DEVID_KBD_BACKLIGHT	0x00050021
 #define ASUS_WMI_DEVID_LIGHT_SENSOR	0x00050022 /* ?? */
 #define ASUS_WMI_DEVID_LIGHTBAR		0x00050025
+/* This can only be used to disable the screen, not re-enable */
+#define ASUS_WMI_DEVID_SCREENPAD_POWER	0x00050031
+/* Writing a brightness re-enables the screen if disabled */
+#define ASUS_WMI_DEVID_SCREENPAD_LIGHT	0x00050032
 #define ASUS_WMI_DEVID_FAN_BOOST_MODE	0x00110018
 #define ASUS_WMI_DEVID_THROTTLE_THERMAL_POLICY 0x00120075
 
-- 
2.41.0

Re: [PATCH v6 1/1] platform/x86: asus-wmi: add support for ASUS screenpad

[Hans de Goede]

Hi Luke,

Thank you for the updated patch.

On 8/30/23 05:22, Luke D. Jones wrote:
> Add support for the WMI methods used to turn off and adjust the
> brightness of the secondary "screenpad" device found on some high-end
> ASUS laptops like the GX650P series and others.
> 
> There are some small quirks with this device when considering only the
> raw WMI methods:
> 1. The Off method can only switch the device off
> 2. Changing the brightness turns the device back on
> 3. To turn the device back on the brightness must be > 1
> 4. When the device is off the brightness can't be changed (so it is
>    stored by the driver if device is off).
> 5. Booting with a value of 0 brightness (retained by bios) means the bios
>    will set a value of >0 <15
> 6. When the device is off it is "unplugged"
> 
> asus_wmi sets the minimum brightness as 20 in general use, and 60 for
> booting with values <= min.
> 
> The ACPI methods are used in a new backlight device named asus_screenpad.
> 
> Signed-off-by: Luke D. Jones <luke@ljones.dev>
> ---
>  drivers/platform/x86/asus-wmi.c            | 133 +++++++++++++++++++++
>  drivers/platform/x86/asus-wmi.h            |   1 +
>  include/linux/platform_data/x86/asus-wmi.h |   4 +
>  3 files changed, 138 insertions(+)
> 
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index f54178d6f780..0b13be703856 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -25,6 +25,7 @@
>  #include <linux/input/sparse-keymap.h>
>  #include <linux/kernel.h>
>  #include <linux/leds.h>
> +#include <linux/minmax.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
>  #include <linux/pci_hotplug.h>
> @@ -127,6 +128,10 @@ module_param(fnlock_default, bool, 0444);
>  #define NVIDIA_TEMP_MIN		75
>  #define NVIDIA_TEMP_MAX		87
>  
> +#define ASUS_SCREENPAD_BRIGHT_MIN 20
> +#define ASUS_SCREENPAD_BRIGHT_MAX 255
> +#define ASUS_SCREENPAD_BRIGHT_DEFAULT 60
> +
>  static const char * const ashs_ids[] = { "ATK4001", "ATK4002", NULL };
>  
>  static int throttle_thermal_policy_write(struct asus_wmi *);
> @@ -212,6 +217,7 @@ struct asus_wmi {
>  
>  	struct input_dev *inputdev;
>  	struct backlight_device *backlight_device;
> +	struct backlight_device *screenpad_backlight_device;
>  	struct platform_device *platform_device;
>  
>  	struct led_classdev wlan_led;
> @@ -3776,6 +3782,124 @@ static int is_display_toggle(int code)
>  	return 0;
>  }
>  
> +/* Screenpad backlight *******************************************************/
> +
> +static int read_screenpad_backlight_power(struct asus_wmi *asus)
> +{
> +	int ret;
> +
> +	ret = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_SCREENPAD_POWER);
> +	if (ret < 0)
> +		return ret;
> +	/* 1 == powered */
> +	return ret ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
> +}
> +
> +static int read_screenpad_brightness(struct backlight_device *bd)
> +{
> +	struct asus_wmi *asus = bl_get_data(bd);
> +	u32 retval;
> +	int err;
> +
> +	err = read_screenpad_backlight_power(asus);
> +	if (err < 0)
> +		return err;
> +	/* The device brightness can only be read if powered, so return stored */
> +	if (err == FB_BLANK_POWERDOWN)
> +		return asus->driver->screenpad_brightness - ASUS_SCREENPAD_BRIGHT_MIN;
> +
> +	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT, &retval);
> +	if (err < 0)
> +		return err;
> +
> +	return (retval & ASUS_WMI_DSTS_BRIGHTNESS_MASK) - ASUS_SCREENPAD_BRIGHT_MIN;
> +}
> +
> +static int update_screenpad_bl_status(struct backlight_device *bd)
> +{
> +	struct asus_wmi *asus = bl_get_data(bd);
> +	int power, err = 0;
> +	u32 ctrl_param;
> +
> +	power = read_screenpad_backlight_power(asus);
> +	if (power < 0)
> +		return power;
> +
> +	if (bd->props.power != power) {
> +		if (power != FB_BLANK_UNBLANK) {
> +			/* Only brightness > 0 can power it back on */
> +			ctrl_param = asus->driver->screenpad_brightness - ASUS_SCREENPAD_BRIGHT_MIN;
> +			err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_LIGHT,
> +						    ctrl_param, NULL);
> +		} else {
> +			err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_POWER, 0, NULL);
> +		}
> +	} else if (power == FB_BLANK_UNBLANK) {
> +		/* Only set brightness if powered on or we get invalid/unsync state */
> +		ctrl_param = bd->props.brightness + ASUS_SCREENPAD_BRIGHT_MIN;
> +		err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_LIGHT, ctrl_param, NULL);
> +	}
> +
> +	/* Ensure brightness is stored to turn back on with */
> +	if (err == 0)
> +		asus->driver->screenpad_brightness = bd->props.brightness + ASUS_SCREENPAD_BRIGHT_MIN;
> +
> +	return err;
> +}
> +
> +static const struct backlight_ops asus_screenpad_bl_ops = {
> +	.get_brightness = read_screenpad_brightness,
> +	.update_status = update_screenpad_bl_status,
> +	.options = BL_CORE_SUSPENDRESUME,
> +};
> +
> +static int asus_screenpad_init(struct asus_wmi *asus)
> +{
> +	struct backlight_device *bd;
> +	struct backlight_properties props;
> +	int err, power;
> +	int brightness = 0;
> +
> +	power = read_screenpad_backlight_power(asus);
> +	if (power < 0)
> +		return power;
> +
> +	if (power != FB_BLANK_POWERDOWN) {
> +		err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT, &brightness);
> +		if (err < 0)
> +			return err;
> +	}
> +	/* default to an acceptable min brightness on boot if too low */
> +	if (brightness < ASUS_SCREENPAD_BRIGHT_MIN)
> +		brightness = ASUS_SCREENPAD_BRIGHT_DEFAULT;
> +
> +	memset(&props, 0, sizeof(struct backlight_properties));
> +	props.type = BACKLIGHT_RAW; /* ensure this bd is last to be picked */
> +	props.max_brightness = ASUS_SCREENPAD_BRIGHT_MAX - ASUS_SCREENPAD_BRIGHT_MIN;
> +	bd = backlight_device_register("asus_screenpad",
> +				       &asus->platform_device->dev, asus,
> +				       &asus_screenpad_bl_ops, &props);
> +	if (IS_ERR(bd)) {
> +		pr_err("Could not register backlight device\n");
> +		return PTR_ERR(bd);
> +	}
> +
> +	asus->screenpad_backlight_device = bd;
> +	asus->driver->screenpad_brightness = brightness;
> +	bd->props.brightness = brightness;

This should be:

	bd->props.brightness = brightness - ASUS_SCREENPAD_BRIGHT_MIN;

Since this is the value exported to userspace which is down-shited
by ASUS_SCREENPAD_BRIGHT_MIN to start at 0.

I have fixed this up while merging this:

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans


> +	bd->props.power = power;
> +	backlight_update_status(bd);
> +
> +	return 0;
> +}
> +
> +static void asus_screenpad_exit(struct asus_wmi *asus)
> +{
> +	backlight_device_unregister(asus->screenpad_backlight_device);
> +
> +	asus->screenpad_backlight_device = NULL;
> +}
> +
>  /* Fn-lock ********************************************************************/
>  
>  static bool asus_wmi_has_fnlock_key(struct asus_wmi *asus)
> @@ -4431,6 +4555,12 @@ static int asus_wmi_add(struct platform_device *pdev)
>  	} else if (asus->driver->quirks->wmi_backlight_set_devstate)
>  		err = asus_wmi_set_devstate(ASUS_WMI_DEVID_BACKLIGHT, 2, NULL);
>  
> +	if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT)) {
> +		err = asus_screenpad_init(asus);
> +		if (err && err != -ENODEV)
> +			goto fail_screenpad;
> +	}
> +
>  	if (asus_wmi_has_fnlock_key(asus)) {
>  		asus->fnlock_locked = fnlock_default;
>  		asus_wmi_fnlock_update(asus);
> @@ -4454,6 +4584,8 @@ static int asus_wmi_add(struct platform_device *pdev)
>  	asus_wmi_backlight_exit(asus);
>  fail_backlight:
>  	asus_wmi_rfkill_exit(asus);
> +fail_screenpad:
> +	asus_screenpad_exit(asus);
>  fail_rfkill:
>  	asus_wmi_led_exit(asus);
>  fail_leds:
> @@ -4480,6 +4612,7 @@ static int asus_wmi_remove(struct platform_device *device)
>  	asus = platform_get_drvdata(device);
>  	wmi_remove_notify_handler(asus->driver->event_guid);
>  	asus_wmi_backlight_exit(asus);
> +	asus_screenpad_exit(asus);
>  	asus_wmi_input_exit(asus);
>  	asus_wmi_led_exit(asus);
>  	asus_wmi_rfkill_exit(asus);
> diff --git a/drivers/platform/x86/asus-wmi.h b/drivers/platform/x86/asus-wmi.h
> index a478ebfd34df..5fbdd0eafa02 100644
> --- a/drivers/platform/x86/asus-wmi.h
> +++ b/drivers/platform/x86/asus-wmi.h
> @@ -57,6 +57,7 @@ struct quirk_entry {
>  struct asus_wmi_driver {
>  	int			brightness;
>  	int			panel_power;
> +	int			screenpad_brightness;
>  	int			wlan_ctrl_by_user;
>  
>  	const char		*name;
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 16e99a1c37fc..63e630276499 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -58,6 +58,10 @@
>  #define ASUS_WMI_DEVID_KBD_BACKLIGHT	0x00050021
>  #define ASUS_WMI_DEVID_LIGHT_SENSOR	0x00050022 /* ?? */
>  #define ASUS_WMI_DEVID_LIGHTBAR		0x00050025
> +/* This can only be used to disable the screen, not re-enable */
> +#define ASUS_WMI_DEVID_SCREENPAD_POWER	0x00050031
> +/* Writing a brightness re-enables the screen if disabled */
> +#define ASUS_WMI_DEVID_SCREENPAD_LIGHT	0x00050032
>  #define ASUS_WMI_DEVID_FAN_BOOST_MODE	0x00110018
>  #define ASUS_WMI_DEVID_THROTTLE_THERMAL_POLICY 0x00120075
>