1 /* 2 * Generic Syscon LEDs Driver 3 * 4 * Copyright (c) 2014, Linaro Limited 5 * Author: Linus Walleij <linus.walleij@linaro.org> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation; either version 2 of 10 * the License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 20 * MA 02111-1307 USA 21 * 22 * This driver provides system reboot functionality for APM X-Gene SoC. 23 * For system shutdown, this is board specify. If a board designer 24 * implements GPIO shutdown, use the gpio-poweroff.c driver. 25 */ 26 #include <linux/io.h> 27 #include <linux/of_device.h> 28 #include <linux/of_address.h> 29 #include <linux/platform_device.h> 30 #include <linux/stat.h> 31 #include <linux/slab.h> 32 #include <linux/mfd/syscon.h> 33 #include <linux/regmap.h> 34 #include <linux/leds.h> 35 36 /** 37 * struct syscon_led - state container for syscon based LEDs 38 * @cdev: LED class device for this LED 39 * @map: regmap to access the syscon device backing this LED 40 * @offset: the offset into the syscon regmap for the LED register 41 * @mask: the bit in the register corresponding to the LED 42 * @state: current state of the LED 43 */ 44 struct syscon_led { 45 struct led_classdev cdev; 46 struct regmap *map; 47 u32 offset; 48 u32 mask; 49 bool state; 50 }; 51 52 static void syscon_led_set(struct led_classdev *led_cdev, 53 enum led_brightness value) 54 { 55 struct syscon_led *sled = 56 container_of(led_cdev, struct syscon_led, cdev); 57 u32 val; 58 int ret; 59 60 if (value == LED_OFF) { 61 val = 0; 62 sled->state = false; 63 } else { 64 val = sled->mask; 65 sled->state = true; 66 } 67 68 ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val); 69 if (ret < 0) 70 dev_err(sled->cdev.dev, "error updating LED status\n"); 71 } 72 73 static const struct of_device_id syscon_match[] = { 74 { .compatible = "syscon", }, 75 {}, 76 }; 77 78 static int __init syscon_leds_init(void) 79 { 80 const struct of_device_id *devid; 81 struct device_node *np; 82 struct device_node *child; 83 struct regmap *map; 84 struct platform_device *pdev; 85 struct device *dev; 86 int ret; 87 88 np = of_find_matching_node_and_match(NULL, syscon_match, 89 &devid); 90 if (!np) 91 return -ENODEV; 92 93 map = syscon_node_to_regmap(np); 94 if (IS_ERR(map)) 95 return PTR_ERR(map); 96 97 /* 98 * If the map is there, the device should be there, we allocate 99 * memory on the syscon device's behalf here. 100 */ 101 pdev = of_find_device_by_node(np); 102 if (!pdev) 103 return -ENODEV; 104 dev = &pdev->dev; 105 106 for_each_available_child_of_node(np, child) { 107 struct syscon_led *sled; 108 const char *state; 109 110 /* Only check for register-bit-leds */ 111 if (of_property_match_string(child, "compatible", 112 "register-bit-led") < 0) 113 continue; 114 115 sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL); 116 if (!sled) 117 return -ENOMEM; 118 119 sled->map = map; 120 121 if (of_property_read_u32(child, "offset", &sled->offset)) 122 return -EINVAL; 123 if (of_property_read_u32(child, "mask", &sled->mask)) 124 return -EINVAL; 125 sled->cdev.name = 126 of_get_property(child, "label", NULL) ? : child->name; 127 sled->cdev.default_trigger = 128 of_get_property(child, "linux,default-trigger", NULL); 129 130 state = of_get_property(child, "default-state", NULL); 131 if (state) { 132 if (!strcmp(state, "keep")) { 133 u32 val; 134 135 ret = regmap_read(map, sled->offset, &val); 136 if (ret < 0) 137 return ret; 138 sled->state = !!(val & sled->mask); 139 } else if (!strcmp(state, "on")) { 140 sled->state = true; 141 ret = regmap_update_bits(map, sled->offset, 142 sled->mask, 143 sled->mask); 144 if (ret < 0) 145 return ret; 146 } else { 147 sled->state = false; 148 ret = regmap_update_bits(map, sled->offset, 149 sled->mask, 0); 150 if (ret < 0) 151 return ret; 152 } 153 154 } 155 sled->cdev.brightness_set = syscon_led_set; 156 157 ret = led_classdev_register(dev, &sled->cdev); 158 if (ret < 0) 159 return ret; 160 161 dev_info(dev, "registered LED %s\n", sled->cdev.name); 162 } 163 164 return 0; 165 } 166 device_initcall(syscon_leds_init); 167