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authorHans de Goede <hdegoede@redhat.com>2024-05-09 17:12:06 +0300
committerHans de Goede <hdegoede@redhat.com>2024-05-14 12:43:40 +0300
commit9426adb0326a87ed2fa9d010c4c18189047e0c11 (patch)
tree785979deb39ffe5c205319f5e8f7d266dcd935c9
parent0b57e2e43c4d257b60c93e9d86ac7a850e21253f (diff)
downloadlinux-9426adb0326a87ed2fa9d010c4c18189047e0c11.tar.xz
platform/x86: x86-android-tablets: Create LED device for Xiaomi Pad 2 bottom bezel touch buttons
The Xiaomi [Mi]Pad 2 has 3 menu / home / back capacitive touch-buttons on its bottom bezel. These are backlit by LEDs attached to a TPS61158 LED controller which is controlled by the "pwm_soc_lpss_2" PWM output. Create a LED class device for this, using the new input-events trigger as default trigger so that the buttons automatically light up on any input activity. Note alternatively a "leds_pwm" platform device could be created together with the necessary fwnode_s_ and a fwnode link to the PWM controller. There are 2 downsides to this approach: 1. The code would still need to pwm_get() the PWM controller to get/attach a fwnode for the PWM controller fwnode link and setting up the necessary fwnodes is non-trivial. So this would likely require more code then simply registering the LED class device directly. 2. Currently the leds_pwm driver and its devicetree bindings do not support limiting the maximum dutycycle to less then 100% which is required in this case (the leds_pwm driver can probably be extended to allow this). Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20240509141207.63570-2-hdegoede@redhat.com
-rw-r--r--drivers/platform/x86/x86-android-tablets/other.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/drivers/platform/x86/x86-android-tablets/other.c b/drivers/platform/x86/x86-android-tablets/other.c
index ff7b1d0abaa3..eb0e55c69dfe 100644
--- a/drivers/platform/x86/x86-android-tablets/other.c
+++ b/drivers/platform/x86/x86-android-tablets/other.c
@@ -11,7 +11,9 @@
#include <linux/acpi.h>
#include <linux/gpio/machine.h>
#include <linux/input.h>
+#include <linux/leds.h>
#include <linux/platform_device.h>
+#include <linux/pwm.h>
#include <dt-bindings/leds/common.h>
@@ -662,8 +664,53 @@ static const struct software_node *ktd2026_node_group[] = {
NULL
};
+/*
+ * For the LEDs which backlight the menu / home / back capacitive buttons on
+ * the bottom bezel. These are attached to a TPS61158 LED controller which
+ * is controlled by the "pwm_soc_lpss_2" PWM output.
+ */
+#define XIAOMI_MIPAD2_LED_PERIOD_NS 19200
+#define XIAOMI_MIPAD2_LED_DEFAULT_DUTY 6000 /* From Android kernel */
+
+static struct pwm_device *xiaomi_mipad2_led_pwm;
+
+static int xiaomi_mipad2_brightness_set(struct led_classdev *led_cdev,
+ enum led_brightness val)
+{
+ struct pwm_state state = {
+ .period = XIAOMI_MIPAD2_LED_PERIOD_NS,
+ .duty_cycle = val,
+ /* Always set PWM enabled to avoid the pin floating */
+ .enabled = true,
+ };
+
+ return pwm_apply_might_sleep(xiaomi_mipad2_led_pwm, &state);
+}
+
static int __init xiaomi_mipad2_init(struct device *dev)
{
+ struct led_classdev *led_cdev;
+ int ret;
+
+ xiaomi_mipad2_led_pwm = devm_pwm_get(dev, "pwm_soc_lpss_2");
+ if (IS_ERR(xiaomi_mipad2_led_pwm))
+ return dev_err_probe(dev, PTR_ERR(xiaomi_mipad2_led_pwm), "getting pwm\n");
+
+ led_cdev = devm_kzalloc(dev, sizeof(*led_cdev), GFP_KERNEL);
+ if (!led_cdev)
+ return -ENOMEM;
+
+ led_cdev->name = "mipad2:white:touch-buttons-backlight";
+ led_cdev->max_brightness = XIAOMI_MIPAD2_LED_PERIOD_NS;
+ /* "input-events" trigger uses blink_brightness */
+ led_cdev->blink_brightness = XIAOMI_MIPAD2_LED_DEFAULT_DUTY;
+ led_cdev->default_trigger = "input-events";
+ led_cdev->brightness_set_blocking = xiaomi_mipad2_brightness_set;
+
+ ret = devm_led_classdev_register(dev, led_cdev);
+ if (ret)
+ return dev_err_probe(dev, ret, "registering LED\n");
+
return software_node_register_node_group(ktd2026_node_group);
}