diff options
Diffstat (limited to 'drivers/leds/leds-pwm.c')
| -rw-r--r-- | drivers/leds/leds-pwm.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c new file mode 100644 index 000000000..1d07e3e83 --- /dev/null +++ b/drivers/leds/leds-pwm.c @@ -0,0 +1,241 @@ +/* + * 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> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/of_platform.h> +#include <linux/fb.h> +#include <linux/leds.h> +#include <linux/err.h> +#include <linux/pwm.h> +#include <linux/leds_pwm.h> +#include <linux/slab.h> +#include <linux/workqueue.h> + +struct led_pwm_data { + struct led_classdev cdev; + struct pwm_device *pwm; + struct work_struct work; + unsigned int active_low; + unsigned int period; + int duty; + bool can_sleep; +}; + +struct led_pwm_priv { + int num_leds; + struct led_pwm_data leds[0]; +}; + +static void __led_pwm_set(struct led_pwm_data *led_dat) +{ + int new_duty = led_dat->duty; + + pwm_config(led_dat->pwm, new_duty, led_dat->period); + + if (new_duty == 0) + pwm_disable(led_dat->pwm); + else + pwm_enable(led_dat->pwm); +} + +static void led_pwm_work(struct work_struct *work) +{ + struct led_pwm_data *led_dat = + container_of(work, struct led_pwm_data, work); + + __led_pwm_set(led_dat); +} + +static void 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->period; + + duty *= brightness; + do_div(duty, max); + + if (led_dat->active_low) + duty = led_dat->period - duty; + + led_dat->duty = duty; + + if (led_dat->can_sleep) + schedule_work(&led_dat->work); + else + __led_pwm_set(led_dat); +} + +static inline size_t sizeof_pwm_leds_priv(int num_leds) +{ + return sizeof(struct led_pwm_priv) + + (sizeof(struct led_pwm_data) * num_leds); +} + +static void led_pwm_cleanup(struct led_pwm_priv *priv) +{ + while (priv->num_leds--) { + led_classdev_unregister(&priv->leds[priv->num_leds].cdev); + if (priv->leds[priv->num_leds].can_sleep) + cancel_work_sync(&priv->leds[priv->num_leds].work); + } +} + +static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, + struct led_pwm *led, struct device_node *child) +{ + struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; + int ret; + + led_data->active_low = led->active_low; + led_data->cdev.name = led->name; + led_data->cdev.default_trigger = led->default_trigger; + led_data->cdev.brightness_set = led_pwm_set; + led_data->cdev.brightness = LED_OFF; + led_data->cdev.max_brightness = led->max_brightness; + led_data->cdev.flags = LED_CORE_SUSPENDRESUME; + + if (child) + led_data->pwm = devm_of_pwm_get(dev, child, NULL); + else + led_data->pwm = devm_pwm_get(dev, led->name); + if (IS_ERR(led_data->pwm)) { + ret = PTR_ERR(led_data->pwm); + dev_err(dev, "unable to request PWM for %s: %d\n", + led->name, ret); + return ret; + } + + led_data->can_sleep = pwm_can_sleep(led_data->pwm); + if (led_data->can_sleep) + INIT_WORK(&led_data->work, led_pwm_work); + + led_data->period = pwm_get_period(led_data->pwm); + if (!led_data->period && (led->pwm_period_ns > 0)) + led_data->period = led->pwm_period_ns; + + ret = led_classdev_register(dev, &led_data->cdev); + if (ret == 0) { + priv->num_leds++; + } else { + dev_err(dev, "failed to register PWM led for %s: %d\n", + led->name, ret); + } + + return ret; +} + +static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) +{ + struct device_node *child; + struct led_pwm led; + int ret = 0; + + memset(&led, 0, sizeof(led)); + + for_each_child_of_node(dev->of_node, child) { + led.name = of_get_property(child, "label", NULL) ? : + child->name; + + led.default_trigger = of_get_property(child, + "linux,default-trigger", NULL); + led.active_low = of_property_read_bool(child, "active-low"); + of_property_read_u32(child, "max-brightness", + &led.max_brightness); + + ret = led_pwm_add(dev, priv, &led, child); + if (ret) { + of_node_put(child); + break; + } + } + + return ret; +} + +static int led_pwm_probe(struct platform_device *pdev) +{ + struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); + struct led_pwm_priv *priv; + int count, i; + int ret = 0; + + if (pdata) + count = pdata->num_leds; + else + count = of_get_child_count(pdev->dev.of_node); + + if (!count) + return -EINVAL; + + priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), + GFP_KERNEL); + if (!priv) + return -ENOMEM; + + if (pdata) { + for (i = 0; i < count; i++) { + ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], + NULL); + if (ret) + break; + } + } else { + ret = led_pwm_create_of(&pdev->dev, priv); + } + + if (ret) { + led_pwm_cleanup(priv); + return ret; + } + + platform_set_drvdata(pdev, priv); + + return 0; +} + +static int led_pwm_remove(struct platform_device *pdev) +{ + struct led_pwm_priv *priv = platform_get_drvdata(pdev); + + led_pwm_cleanup(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, + .remove = led_pwm_remove, + .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("PWM LED driver for PXA"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:leds-pwm"); |