[PATCH v2 8/9] platform/x86: asus-wmi: Add support for MCU powersave

["Luke D. Jones" <luke@ljones.dev>]

Add support for an MCU powersave WMI call. This is intended to set the
MCU in to a low-power mode when sleeping. This mode can cut sleep power
use by around half.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
---
 .../ABI/testing/sysfs-platform-asus-wmi       | 11 +++-
 drivers/platform/x86/asus-wmi.c               | 50 +++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-platform-asus-wmi b/Documentation/ABI/testing/sysfs-platform-asus-wmi
index 41b92e53e88a..28144371a0f1 100644
--- a/Documentation/ABI/testing/sysfs-platform-asus-wmi
+++ b/Documentation/ABI/testing/sysfs-platform-asus-wmi
@@ -202,4 +202,13 @@ Contact:	"Luke Jones" <luke@ljones.dev>
 Description:
 		Set if the BIOS POST sound is played on boot.
 			* 0 - False,
-			* 1 - True
\ No newline at end of file
+			* 1 - True
+
+What:		/sys/devices/platform/<platform>/mcu_powersave
+Date:		Apr 2024
+KernelVersion:	6.10
+Contact:	"Luke Jones" <luke@ljones.dev>
+Description:
+		Set if the MCU can go in to low-power mode on system sleep
+			* 0 - False,
+			* 1 - True
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index ddf568ef8c5e..cf872eed0986 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1292,6 +1292,53 @@ static ssize_t nv_temp_target_show(struct device *dev,
 }
 static DEVICE_ATTR_RW(nv_temp_target);
 
+/* Ally MCU Powersave ********************************************************/
+static ssize_t mcu_powersave_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+	int result;
+
+	result = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_MCU_POWERSAVE);
+	if (result < 0)
+		return result;
+
+	return sysfs_emit(buf, "%d\n", result);
+}
+
+static ssize_t mcu_powersave_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	int result, err;
+	u32 enable;
+
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+
+	result = kstrtou32(buf, 10, &enable);
+	if (result)
+		return result;
+
+	if (enable > 1)
+		return -EINVAL;
+
+	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_MCU_POWERSAVE, enable, &result);
+	if (err) {
+		pr_warn("Failed to set MCU powersave: %d\n", err);
+		return err;
+	}
+
+	if (result > 1) {
+		pr_warn("Failed to set MCU powersave (result): 0x%x\n", result);
+		return -EIO;
+	}
+
+	sysfs_notify(&asus->platform_device->dev.kobj, NULL, "mcu_powersave");
+
+	return count;
+}
+static DEVICE_ATTR_RW(mcu_powersave);
+
 /* Battery ********************************************************************/
 
 /* The battery maximum charging percentage */
@@ -4299,6 +4346,7 @@ static struct attribute *platform_attributes[] = {
 	&dev_attr_ppt_platform_sppt.attr,
 	&dev_attr_nv_dynamic_boost.attr,
 	&dev_attr_nv_temp_target.attr,
+	&dev_attr_mcu_powersave.attr,
 	&dev_attr_boot_sound.attr,
 	&dev_attr_panel_od.attr,
 	&dev_attr_mini_led_mode.attr,
@@ -4352,6 +4400,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
 		devid = ASUS_WMI_DEVID_NV_DYN_BOOST;
 	else if (attr == &dev_attr_nv_temp_target.attr)
 		devid = ASUS_WMI_DEVID_NV_THERM_TARGET;
+	else if (attr == &dev_attr_mcu_powersave.attr)
+		devid = ASUS_WMI_DEVID_MCU_POWERSAVE;
 	else if (attr == &dev_attr_boot_sound.attr)
 		devid = ASUS_WMI_DEVID_BOOT_SOUND;
 	else if (attr == &dev_attr_panel_od.attr)
-- 
2.44.0