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/platform_device.h> 21 #include <linux/leds.h> 22 #include <linux/workqueue.h> 23 #include <linux/delay.h> 24 #include <linux/gpio.h> 25 #include <linux/slab.h> 26 #include <linux/module.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 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 dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n", 92 KBUILD_MODNAME, template->gpio, template->name); 93 return 0; 94 } 95 96 led_dat->cdev.name = template->name; 97 led_dat->cdev.default_trigger = template->default_trigger; 98 led_dat->gpio = template->gpio; 99 100 led_dat->cdev.brightness_set = lt3593_led_set; 101 102 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); 103 led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; 104 105 if (!template->retain_state_suspended) 106 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 107 108 ret = devm_gpio_request_one(parent, template->gpio, state ? 109 GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW, 110 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 = dev_get_platdata(&pdev->dev); 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 = dev_get_platdata(&pdev->dev); 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 }, 188 }; 189 190 module_platform_driver(lt3593_led_driver); 191 192 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); 193 MODULE_DESCRIPTION("LED driver for LT3593 controllers"); 194 MODULE_LICENSE("GPL"); 195 MODULE_ALIAS("platform:leds-lt3593"); 196