diff options
Diffstat (limited to 'drivers/leds/leds-pwm.c')
| -rw-r--r-- | drivers/leds/leds-pwm.c | 217 |
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 000000000..6d3e33e8b --- /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_platform.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; + + memset(&led, 0, sizeof(led)); + + device_for_each_child_node(dev, fwnode) { + 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"); |