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/delay.h> 23 #include <linux/gpio.h> 24 #include <linux/slab.h> 25 #include <linux/module.h> 26 27 struct lt3593_led_data { 28 struct led_classdev cdev; 29 unsigned gpio; 30 }; 31 32 static int lt3593_led_set(struct led_classdev *led_cdev, 33 enum led_brightness value) 34 { 35 struct lt3593_led_data *led_dat = 36 container_of(led_cdev, struct lt3593_led_data, cdev); 37 int pulses; 38 39 /* 40 * The LT3593 resets its internal current level register to the maximum 41 * level on the first falling edge on the control pin. Each following 42 * falling edge decreases the current level by 625uA. Up to 32 pulses 43 * can be sent, so the maximum power reduction is 20mA. 44 * After a timeout of 128us, the value is taken from the register and 45 * applied is to the output driver. 46 */ 47 48 if (value == 0) { 49 gpio_set_value_cansleep(led_dat->gpio, 0); 50 return 0; 51 } 52 53 pulses = 32 - (value * 32) / 255; 54 55 if (pulses == 0) { 56 gpio_set_value_cansleep(led_dat->gpio, 0); 57 mdelay(1); 58 gpio_set_value_cansleep(led_dat->gpio, 1); 59 return 0; 60 } 61 62 gpio_set_value_cansleep(led_dat->gpio, 1); 63 64 while (pulses--) { 65 gpio_set_value_cansleep(led_dat->gpio, 0); 66 udelay(1); 67 gpio_set_value_cansleep(led_dat->gpio, 1); 68 udelay(1); 69 } 70 71 return 0; 72 } 73 74 static int create_lt3593_led(const struct gpio_led *template, 75 struct lt3593_led_data *led_dat, struct device *parent) 76 { 77 int ret, state; 78 79 /* skip leds on GPIOs that aren't available */ 80 if (!gpio_is_valid(template->gpio)) { 81 dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n", 82 KBUILD_MODNAME, template->gpio, template->name); 83 return 0; 84 } 85 86 led_dat->cdev.name = template->name; 87 led_dat->cdev.default_trigger = template->default_trigger; 88 led_dat->gpio = template->gpio; 89 90 led_dat->cdev.brightness_set_blocking = lt3593_led_set; 91 92 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); 93 led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; 94 95 if (!template->retain_state_suspended) 96 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 97 98 ret = devm_gpio_request_one(parent, template->gpio, state ? 99 GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW, 100 template->name); 101 if (ret < 0) 102 return ret; 103 104 ret = led_classdev_register(parent, &led_dat->cdev); 105 if (ret < 0) 106 return ret; 107 108 dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n", 109 KBUILD_MODNAME, template->name, template->gpio); 110 111 return 0; 112 } 113 114 static void delete_lt3593_led(struct lt3593_led_data *led) 115 { 116 if (!gpio_is_valid(led->gpio)) 117 return; 118 119 led_classdev_unregister(&led->cdev); 120 } 121 122 static int lt3593_led_probe(struct platform_device *pdev) 123 { 124 struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev); 125 struct lt3593_led_data *leds_data; 126 int i, ret = 0; 127 128 if (!pdata) 129 return -EBUSY; 130 131 leds_data = devm_kcalloc(&pdev->dev, 132 pdata->num_leds, sizeof(struct lt3593_led_data), 133 GFP_KERNEL); 134 if (!leds_data) 135 return -ENOMEM; 136 137 for (i = 0; i < pdata->num_leds; i++) { 138 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i], 139 &pdev->dev); 140 if (ret < 0) 141 goto err; 142 } 143 144 platform_set_drvdata(pdev, leds_data); 145 146 return 0; 147 148 err: 149 for (i = i - 1; i >= 0; i--) 150 delete_lt3593_led(&leds_data[i]); 151 152 return ret; 153 } 154 155 static int lt3593_led_remove(struct platform_device *pdev) 156 { 157 int i; 158 struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev); 159 struct lt3593_led_data *leds_data; 160 161 leds_data = platform_get_drvdata(pdev); 162 163 for (i = 0; i < pdata->num_leds; i++) 164 delete_lt3593_led(&leds_data[i]); 165 166 return 0; 167 } 168 169 static struct platform_driver lt3593_led_driver = { 170 .probe = lt3593_led_probe, 171 .remove = lt3593_led_remove, 172 .driver = { 173 .name = "leds-lt3593", 174 }, 175 }; 176 177 module_platform_driver(lt3593_led_driver); 178 179 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); 180 MODULE_DESCRIPTION("LED driver for LT3593 controllers"); 181 MODULE_LICENSE("GPL"); 182 MODULE_ALIAS("platform:leds-lt3593"); 183