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 #include <linux/module.h> 28 29 struct lt3593_led_data { 30 struct led_classdev cdev; 31 unsigned gpio; 32 struct work_struct work; 33 u8 new_level; 34 }; 35 36 static void lt3593_led_work(struct work_struct *work) 37 { 38 int pulses; 39 struct lt3593_led_data *led_dat = 40 container_of(work, struct lt3593_led_data, work); 41 42 /* 43 * The LT3593 resets its internal current level register to the maximum 44 * level on the first falling edge on the control pin. Each following 45 * falling edge decreases the current level by 625uA. Up to 32 pulses 46 * can be sent, so the maximum power reduction is 20mA. 47 * After a timeout of 128us, the value is taken from the register and 48 * applied is to the output driver. 49 */ 50 51 if (led_dat->new_level == 0) { 52 gpio_set_value_cansleep(led_dat->gpio, 0); 53 return; 54 } 55 56 pulses = 32 - (led_dat->new_level * 32) / 255; 57 58 if (pulses == 0) { 59 gpio_set_value_cansleep(led_dat->gpio, 0); 60 mdelay(1); 61 gpio_set_value_cansleep(led_dat->gpio, 1); 62 return; 63 } 64 65 gpio_set_value_cansleep(led_dat->gpio, 1); 66 67 while (pulses--) { 68 gpio_set_value_cansleep(led_dat->gpio, 0); 69 udelay(1); 70 gpio_set_value_cansleep(led_dat->gpio, 1); 71 udelay(1); 72 } 73 } 74 75 static void lt3593_led_set(struct led_classdev *led_cdev, 76 enum led_brightness value) 77 { 78 struct lt3593_led_data *led_dat = 79 container_of(led_cdev, struct lt3593_led_data, cdev); 80 81 led_dat->new_level = value; 82 schedule_work(&led_dat->work); 83 } 84 85 static int create_lt3593_led(const struct gpio_led *template, 86 struct lt3593_led_data *led_dat, struct device *parent) 87 { 88 int ret, state; 89 90 /* skip leds on GPIOs that aren't available */ 91 if (!gpio_is_valid(template->gpio)) { 92 dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n", 93 KBUILD_MODNAME, template->gpio, template->name); 94 return 0; 95 } 96 97 led_dat->cdev.name = template->name; 98 led_dat->cdev.default_trigger = template->default_trigger; 99 led_dat->gpio = template->gpio; 100 101 led_dat->cdev.brightness_set = lt3593_led_set; 102 103 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); 104 led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; 105 106 if (!template->retain_state_suspended) 107 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 108 109 ret = devm_gpio_request_one(parent, template->gpio, 110 GPIOF_DIR_OUT | state, template->name); 111 if (ret < 0) 112 return ret; 113 114 INIT_WORK(&led_dat->work, lt3593_led_work); 115 116 ret = led_classdev_register(parent, &led_dat->cdev); 117 if (ret < 0) 118 return ret; 119 120 dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n", 121 KBUILD_MODNAME, template->name, template->gpio); 122 123 return 0; 124 } 125 126 static void delete_lt3593_led(struct lt3593_led_data *led) 127 { 128 if (!gpio_is_valid(led->gpio)) 129 return; 130 131 led_classdev_unregister(&led->cdev); 132 cancel_work_sync(&led->work); 133 } 134 135 static int lt3593_led_probe(struct platform_device *pdev) 136 { 137 struct gpio_led_platform_data *pdata = pdev->dev.platform_data; 138 struct lt3593_led_data *leds_data; 139 int i, ret = 0; 140 141 if (!pdata) 142 return -EBUSY; 143 144 leds_data = devm_kzalloc(&pdev->dev, 145 sizeof(struct lt3593_led_data) * pdata->num_leds, 146 GFP_KERNEL); 147 if (!leds_data) 148 return -ENOMEM; 149 150 for (i = 0; i < pdata->num_leds; i++) { 151 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i], 152 &pdev->dev); 153 if (ret < 0) 154 goto err; 155 } 156 157 platform_set_drvdata(pdev, leds_data); 158 159 return 0; 160 161 err: 162 for (i = i - 1; i >= 0; i--) 163 delete_lt3593_led(&leds_data[i]); 164 165 return ret; 166 } 167 168 static int lt3593_led_remove(struct platform_device *pdev) 169 { 170 int i; 171 struct gpio_led_platform_data *pdata = pdev->dev.platform_data; 172 struct lt3593_led_data *leds_data; 173 174 leds_data = platform_get_drvdata(pdev); 175 176 for (i = 0; i < pdata->num_leds; i++) 177 delete_lt3593_led(&leds_data[i]); 178 179 return 0; 180 } 181 182 static struct platform_driver lt3593_led_driver = { 183 .probe = lt3593_led_probe, 184 .remove = lt3593_led_remove, 185 .driver = { 186 .name = "leds-lt3593", 187 .owner = THIS_MODULE, 188 }, 189 }; 190 191 module_platform_driver(lt3593_led_driver); 192 193 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); 194 MODULE_DESCRIPTION("LED driver for LT3593 controllers"); 195 MODULE_LICENSE("GPL"); 196 MODULE_ALIAS("platform:leds-lt3593"); 197