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authorDenis Osterland-Heim <Denis.Osterland@diehl.com>2021-06-08 08:35:54 +0200
committerPavel Machek <pavel@ucw.cz>2021-08-18 08:27:31 +0200
commit3d3d65bd27645830a6f23af29d0f9ebe5cc8bcb2 (patch)
tree4a62c84f7b32b57d79349369193c92769c1fac20
parent791bc41163c51f870972d6c6b82d971ce951096c (diff)
leds: pwm: add support for default-state device property
This patch adds support for "default-state" devicetree property, which allows to defer pwm init to first use of led. This allows to configure the PWM early in bootloader to let the LED blink until an application in Linux userspace sets something different. Signed-off-by: Denis Osterland-Heim <Denis.Osterland@diehl.com> Signed-off-by: Pavel Machek <pavel@ucw.cz>
-rw-r--r--drivers/leds/leds-pwm.c49
1 files changed, 43 insertions, 6 deletions
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index d71e9fa5c8de..6832180c1c54 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -17,10 +17,12 @@
#include <linux/err.h>
#include <linux/pwm.h>
#include <linux/slab.h>
+#include "leds.h"
struct led_pwm {
const char *name;
u8 active_low;
+ u8 default_state;
unsigned int max_brightness;
};
@@ -77,7 +79,38 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
led_data->cdev.brightness_set_blocking = led_pwm_set;
- pwm_init_state(led_data->pwm, &led_data->pwmstate);
+ /* init PWM state */
+ switch (led->default_state) {
+ case LEDS_DEFSTATE_KEEP:
+ pwm_get_state(led_data->pwm, &led_data->pwmstate);
+ if (led_data->pwmstate.period)
+ break;
+ led->default_state = LEDS_DEFSTATE_OFF;
+ dev_warn(dev,
+ "failed to read period for %s, default to off",
+ led->name);
+ fallthrough;
+ default:
+ pwm_init_state(led_data->pwm, &led_data->pwmstate);
+ break;
+ }
+
+ /* set brightness */
+ switch (led->default_state) {
+ case LEDS_DEFSTATE_ON:
+ led_data->cdev.brightness = led->max_brightness;
+ break;
+ case LEDS_DEFSTATE_KEEP:
+ {
+ uint64_t brightness;
+
+ brightness = led->max_brightness;
+ brightness *= led_data->pwmstate.duty_cycle;
+ do_div(brightness, led_data->pwmstate.period);
+ led_data->cdev.brightness = brightness;
+ }
+ break;
+ }
ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
if (ret) {
@@ -86,11 +119,13 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
return ret;
}
- ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
- if (ret) {
- dev_err(dev, "failed to set led PWM value for %s: %d",
- led->name, ret);
- return ret;
+ if (led->default_state != LEDS_DEFSTATE_KEEP) {
+ ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
+ if (ret) {
+ dev_err(dev, "failed to set led PWM value for %s: %d",
+ led->name, ret);
+ return ret;
+ }
}
priv->num_leds++;
@@ -120,6 +155,8 @@ static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
fwnode_property_read_u32(fwnode, "max-brightness",
&led.max_brightness);
+ led.default_state = led_init_default_state_get(fwnode);
+
ret = led_pwm_add(dev, priv, &led, fwnode);
if (ret)
goto err_child_out;