1 /* 2 * LEDs driver for LT3593 controllers 3 * 4 * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf 5 * 6 * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de> 7 * 8 * Based on leds-gpio.c, 9 * 10 * Copyright (C) 2007 8D Technologies inc. 11 * Raphael Assenat <raph@8d.com> 12 * Copyright (C) 2008 Freescale Semiconductor, Inc. 13 * 14 * This program is free software; you can redistribute it and/or modify 15 * it under the terms of the GNU General Public License version 2 as 16 * published by the Free Software Foundation. 17 */ 18 19 #include <linux/kernel.h> 20 #include <linux/init.h> 21 #include <linux/platform_device.h> 22 #include <linux/leds.h> 23 #include <linux/workqueue.h> 24 #include <linux/delay.h> 25 #include <linux/gpio.h> 26 #include <linux/slab.h> 27 28 struct lt3593_led_data { 29 struct led_classdev cdev; 30 unsigned gpio; 31 struct work_struct work; 32 u8 new_level; 33 }; 34 35 static void lt3593_led_work(struct work_struct *work) 36 { 37 int pulses; 38 struct lt3593_led_data *led_dat = 39 container_of(work, struct lt3593_led_data, work); 40 41 /* 42 * The LT3593 resets its internal current level register to the maximum 43 * level on the first falling edge on the control pin. Each following 44 * falling edge decreases the current level by 625uA. Up to 32 pulses 45 * can be sent, so the maximum power reduction is 20mA. 46 * After a timeout of 128us, the value is taken from the register and 47 * applied is to the output driver. 48 */ 49 50 if (led_dat->new_level == 0) { 51 gpio_set_value_cansleep(led_dat->gpio, 0); 52 return; 53 } 54 55 pulses = 32 - (led_dat->new_level * 32) / 255; 56 57 if (pulses == 0) { 58 gpio_set_value_cansleep(led_dat->gpio, 0); 59 mdelay(1); 60 gpio_set_value_cansleep(led_dat->gpio, 1); 61 return; 62 } 63 64 gpio_set_value_cansleep(led_dat->gpio, 1); 65 66 while (pulses--) { 67 gpio_set_value_cansleep(led_dat->gpio, 0); 68 udelay(1); 69 gpio_set_value_cansleep(led_dat->gpio, 1); 70 udelay(1); 71 } 72 } 73 74 static void lt3593_led_set(struct led_classdev *led_cdev, 75 enum led_brightness value) 76 { 77 struct lt3593_led_data *led_dat = 78 container_of(led_cdev, struct lt3593_led_data, cdev); 79 80 led_dat->new_level = value; 81 schedule_work(&led_dat->work); 82 } 83 84 static int __devinit create_lt3593_led(const struct gpio_led *template, 85 struct lt3593_led_data *led_dat, struct device *parent) 86 { 87 int ret, state; 88 89 /* skip leds on GPIOs that aren't available */ 90 if (!gpio_is_valid(template->gpio)) { 91 printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n", 92 KBUILD_MODNAME, template->gpio, template->name); 93 return 0; 94 } 95 96 ret = gpio_request(template->gpio, template->name); 97 if (ret < 0) 98 return ret; 99 100 led_dat->cdev.name = template->name; 101 led_dat->cdev.default_trigger = template->default_trigger; 102 led_dat->gpio = template->gpio; 103 104 led_dat->cdev.brightness_set = lt3593_led_set; 105 106 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); 107 led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; 108 109 if (!template->retain_state_suspended) 110 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 111 112 ret = gpio_direction_output(led_dat->gpio, state); 113 if (ret < 0) 114 goto err; 115 116 INIT_WORK(&led_dat->work, lt3593_led_work); 117 118 ret = led_classdev_register(parent, &led_dat->cdev); 119 if (ret < 0) 120 goto err; 121 122 printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n", 123 KBUILD_MODNAME, template->name, template->gpio); 124 125 return 0; 126 127 err: 128 gpio_free(led_dat->gpio); 129 return ret; 130 } 131 132 static void delete_lt3593_led(struct lt3593_led_data *led) 133 { 134 if (!gpio_is_valid(led->gpio)) 135 return; 136 137 led_classdev_unregister(&led->cdev); 138 cancel_work_sync(&led->work); 139 gpio_free(led->gpio); 140 } 141 142 static int __devinit lt3593_led_probe(struct platform_device *pdev) 143 { 144 struct gpio_led_platform_data *pdata = pdev->dev.platform_data; 145 struct lt3593_led_data *leds_data; 146 int i, ret = 0; 147 148 if (!pdata) 149 return -EBUSY; 150 151 leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds, 152 GFP_KERNEL); 153 if (!leds_data) 154 return -ENOMEM; 155 156 for (i = 0; i < pdata->num_leds; i++) { 157 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i], 158 &pdev->dev); 159 if (ret < 0) 160 goto err; 161 } 162 163 platform_set_drvdata(pdev, leds_data); 164 165 return 0; 166 167 err: 168 for (i = i - 1; i >= 0; i--) 169 delete_lt3593_led(&leds_data[i]); 170 171 kfree(leds_data); 172 173 return ret; 174 } 175 176 static int __devexit lt3593_led_remove(struct platform_device *pdev) 177 { 178 int i; 179 struct gpio_led_platform_data *pdata = pdev->dev.platform_data; 180 struct lt3593_led_data *leds_data; 181 182 leds_data = platform_get_drvdata(pdev); 183 184 for (i = 0; i < pdata->num_leds; i++) 185 delete_lt3593_led(&leds_data[i]); 186 187 kfree(leds_data); 188 189 return 0; 190 } 191 192 static struct platform_driver lt3593_led_driver = { 193 .probe = lt3593_led_probe, 194 .remove = __devexit_p(lt3593_led_remove), 195 .driver = { 196 .name = "leds-lt3593", 197 .owner = THIS_MODULE, 198 }, 199 }; 200 201 MODULE_ALIAS("platform:leds-lt3593"); 202 203 static int __init lt3593_led_init(void) 204 { 205 return platform_driver_register(<3593_led_driver); 206 } 207 208 static void __exit lt3593_led_exit(void) 209 { 210 platform_driver_unregister(<3593_led_driver); 211 } 212 213 module_init(lt3593_led_init); 214 module_exit(lt3593_led_exit); 215 216 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); 217 MODULE_DESCRIPTION("LED driver for LT3593 controllers"); 218 MODULE_LICENSE("GPL"); 219