/* * 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> #include <linux/slab.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");