diff options
Diffstat (limited to 'drivers/leds/leds-lt3593.c')
| -rw-r--r-- | drivers/leds/leds-lt3593.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/leds/leds-lt3593.c b/drivers/leds/leds-lt3593.c new file mode 100644 index 00000000000..fee40a84195 --- /dev/null +++ b/drivers/leds/leds-lt3593.c @@ -0,0 +1,217 @@ +/* + * LEDs driver for LT3593 controllers + * + * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf + * + * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de> + * + * Based on leds-gpio.c, + * + * Copyright (C) 2007 8D Technologies inc. + * Raphael Assenat <raph@8d.com> + * Copyright (C) 2008 Freescale Semiconductor, Inc. + * + * 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/kernel.h> +#include <linux/init.h> +#include <linux/platform_device.h> +#include <linux/leds.h> +#include <linux/workqueue.h> +#include <linux/delay.h> +#include <linux/gpio.h> + +struct lt3593_led_data { + struct led_classdev cdev; + unsigned gpio; + struct work_struct work; + u8 new_level; +}; + +static void lt3593_led_work(struct work_struct *work) +{ + int pulses; + struct lt3593_led_data *led_dat = + container_of(work, struct lt3593_led_data, work); + + /* + * The LT3593 resets its internal current level register to the maximum + * level on the first falling edge on the control pin. Each following + * falling edge decreases the current level by 625uA. Up to 32 pulses + * can be sent, so the maximum power reduction is 20mA. + * After a timeout of 128us, the value is taken from the register and + * applied is to the output driver. + */ + + if (led_dat->new_level == 0) { + gpio_set_value_cansleep(led_dat->gpio, 0); + return; + } + + pulses = 32 - (led_dat->new_level * 32) / 255; + + if (pulses == 0) { + gpio_set_value_cansleep(led_dat->gpio, 0); + mdelay(1); + gpio_set_value_cansleep(led_dat->gpio, 1); + return; + } + + gpio_set_value_cansleep(led_dat->gpio, 1); + + while (pulses--) { + gpio_set_value_cansleep(led_dat->gpio, 0); + udelay(1); + gpio_set_value_cansleep(led_dat->gpio, 1); + udelay(1); + } +} + +static void lt3593_led_set(struct led_classdev *led_cdev, + enum led_brightness value) +{ + struct lt3593_led_data *led_dat = + container_of(led_cdev, struct lt3593_led_data, cdev); + + led_dat->new_level = value; + schedule_work(&led_dat->work); +} + +static int __devinit create_lt3593_led(const struct gpio_led *template, + struct lt3593_led_data *led_dat, struct device *parent) +{ + int ret, state; + + /* skip leds on GPIOs that aren't available */ + if (!gpio_is_valid(template->gpio)) { + printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n", + KBUILD_MODNAME, template->gpio, template->name); + return 0; + } + + ret = gpio_request(template->gpio, template->name); + if (ret < 0) + return ret; + + led_dat->cdev.name = template->name; + led_dat->cdev.default_trigger = template->default_trigger; + led_dat->gpio = template->gpio; + + led_dat->cdev.brightness_set = lt3593_led_set; + + state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); + led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; + + if (!template->retain_state_suspended) + led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; + + ret = gpio_direction_output(led_dat->gpio, state); + if (ret < 0) + goto err; + + INIT_WORK(&led_dat->work, lt3593_led_work); + + ret = led_classdev_register(parent, &led_dat->cdev); + if (ret < 0) + goto err; + + printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n", + KBUILD_MODNAME, template->name, template->gpio); + + return 0; + +err: + gpio_free(led_dat->gpio); + return ret; +} + +static void delete_lt3593_led(struct lt3593_led_data *led) +{ + if (!gpio_is_valid(led->gpio)) + return; + + led_classdev_unregister(&led->cdev); + cancel_work_sync(&led->work); + gpio_free(led->gpio); +} + +static int __devinit lt3593_led_probe(struct platform_device *pdev) +{ + struct gpio_led_platform_data *pdata = pdev->dev.platform_data; + struct lt3593_led_data *leds_data; + int i, ret = 0; + + if (!pdata) + return -EBUSY; + + leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds, + GFP_KERNEL); + if (!leds_data) + return -ENOMEM; + + for (i = 0; i < pdata->num_leds; i++) { + ret = create_lt3593_led(&pdata->leds[i], &leds_data[i], + &pdev->dev); + if (ret < 0) + goto err; + } + + platform_set_drvdata(pdev, leds_data); + + return 0; + +err: + for (i = i - 1; i >= 0; i--) + delete_lt3593_led(&leds_data[i]); + + kfree(leds_data); + + return ret; +} + +static int __devexit lt3593_led_remove(struct platform_device *pdev) +{ + int i; + struct gpio_led_platform_data *pdata = pdev->dev.platform_data; + struct lt3593_led_data *leds_data; + + leds_data = platform_get_drvdata(pdev); + + for (i = 0; i < pdata->num_leds; i++) + delete_lt3593_led(&leds_data[i]); + + kfree(leds_data); + + return 0; +} + +static struct platform_driver lt3593_led_driver = { + .probe = lt3593_led_probe, + .remove = __devexit_p(lt3593_led_remove), + .driver = { + .name = "leds-lt3593", + .owner = THIS_MODULE, + }, +}; + +MODULE_ALIAS("platform:leds-lt3593"); + +static int __init lt3593_led_init(void) +{ + return platform_driver_register(<3593_led_driver); +} + +static void __exit lt3593_led_exit(void) +{ + platform_driver_unregister(<3593_led_driver); +} + +module_init(lt3593_led_init); +module_exit(lt3593_led_exit); + +MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); +MODULE_DESCRIPTION("LED driver for LT3593 controllers"); +MODULE_LICENSE("GPL"); |