| 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_kzalloc(&pdev->dev, |
| 132 | sizeof(struct lt3593_led_data) * pdata->num_leds, |
| 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"); |