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Diffstat (limited to 'drivers/leds/leds-pwm.c')
-rw-r--r--drivers/leds/leds-pwm.c217
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
new file mode 100644
index 0000000000..2b3bf1353b
--- /dev/null
+++ b/drivers/leds/leds-pwm.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/leds-pwm.c
+ *
+ * simple PWM based LED control
+ *
+ * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
+ *
+ * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/leds.h>
+#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;
+};
+
+struct led_pwm_data {
+ struct led_classdev cdev;
+ struct pwm_device *pwm;
+ struct pwm_state pwmstate;
+ unsigned int active_low;
+};
+
+struct led_pwm_priv {
+ int num_leds;
+ struct led_pwm_data leds[];
+};
+
+static int led_pwm_set(struct led_classdev *led_cdev,
+ enum led_brightness brightness)
+{
+ struct led_pwm_data *led_dat =
+ container_of(led_cdev, struct led_pwm_data, cdev);
+ unsigned int max = led_dat->cdev.max_brightness;
+ unsigned long long duty = led_dat->pwmstate.period;
+
+ duty *= brightness;
+ do_div(duty, max);
+
+ if (led_dat->active_low)
+ duty = led_dat->pwmstate.period - duty;
+
+ led_dat->pwmstate.duty_cycle = duty;
+ led_dat->pwmstate.enabled = true;
+ return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
+}
+
+__attribute__((nonnull))
+static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
+ struct led_pwm *led, struct fwnode_handle *fwnode)
+{
+ struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
+ struct led_init_data init_data = { .fwnode = fwnode };
+ int ret;
+
+ led_data->active_low = led->active_low;
+ led_data->cdev.name = led->name;
+ led_data->cdev.brightness = LED_OFF;
+ led_data->cdev.max_brightness = led->max_brightness;
+ led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
+
+ led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
+ if (IS_ERR(led_data->pwm))
+ return dev_err_probe(dev, PTR_ERR(led_data->pwm),
+ "unable to request PWM for %s\n",
+ led->name);
+
+ led_data->cdev.brightness_set_blocking = led_pwm_set;
+
+ /* 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) {
+ dev_err(dev, "failed to register PWM led for %s: %d\n",
+ 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++;
+ return 0;
+}
+
+static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
+{
+ struct fwnode_handle *fwnode;
+ struct led_pwm led;
+ int ret;
+
+ device_for_each_child_node(dev, fwnode) {
+ memset(&led, 0, sizeof(led));
+
+ ret = fwnode_property_read_string(fwnode, "label", &led.name);
+ if (ret && is_of_node(fwnode))
+ led.name = to_of_node(fwnode)->name;
+
+ if (!led.name) {
+ ret = -EINVAL;
+ goto err_child_out;
+ }
+
+ led.active_low = fwnode_property_read_bool(fwnode,
+ "active-low");
+ 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;
+ }
+
+ return 0;
+
+err_child_out:
+ fwnode_handle_put(fwnode);
+ return ret;
+}
+
+static int led_pwm_probe(struct platform_device *pdev)
+{
+ struct led_pwm_priv *priv;
+ int ret = 0;
+ int count;
+
+ count = device_get_child_node_count(&pdev->dev);
+
+ if (!count)
+ return -EINVAL;
+
+ priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
+ GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ ret = led_pwm_create_fwnode(&pdev->dev, priv);
+
+ if (ret)
+ return ret;
+
+ platform_set_drvdata(pdev, priv);
+
+ return 0;
+}
+
+static const struct of_device_id of_pwm_leds_match[] = {
+ { .compatible = "pwm-leds", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
+
+static struct platform_driver led_pwm_driver = {
+ .probe = led_pwm_probe,
+ .driver = {
+ .name = "leds_pwm",
+ .of_match_table = of_pwm_leds_match,
+ },
+};
+
+module_platform_driver(led_pwm_driver);
+
+MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
+MODULE_DESCRIPTION("generic PWM LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:leds-pwm");