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 #include <linux/io.h> 23 #include <linux/of_device.h> 24 #include <linux/of_address.h> 25 #include <linux/platform_device.h> 26 #include <linux/stat.h> 27 #include <linux/slab.h> 28 #include <linux/mfd/syscon.h> 29 #include <linux/regmap.h> 30 #include <linux/leds.h> 31 32 /** 33 * struct syscon_led - state container for syscon based LEDs 34 * @cdev: LED class device for this LED 35 * @map: regmap to access the syscon device backing this LED 36 * @offset: the offset into the syscon regmap for the LED register 37 * @mask: the bit in the register corresponding to the LED 38 * @state: current state of the LED 39 */ 40 struct syscon_led { 41 struct led_classdev cdev; 42 struct regmap *map; 43 u32 offset; 44 u32 mask; 45 bool state; 46 }; 47 48 static void syscon_led_set(struct led_classdev *led_cdev, 49 enum led_brightness value) 50 { 51 struct syscon_led *sled = 52 container_of(led_cdev, struct syscon_led, cdev); 53 u32 val; 54 int ret; 55 56 if (value == LED_OFF) { 57 val = 0; 58 sled->state = false; 59 } else { 60 val = sled->mask; 61 sled->state = true; 62 } 63 64 ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val); 65 if (ret < 0) 66 dev_err(sled->cdev.dev, "error updating LED status\n"); 67 } 68 69 static int __init syscon_leds_spawn(struct device_node *np, 70 struct device *dev, 71 struct regmap *map) 72 { 73 struct device_node *child; 74 int ret; 75 76 for_each_available_child_of_node(np, child) { 77 struct syscon_led *sled; 78 const char *state; 79 80 /* Only check for register-bit-leds */ 81 if (of_property_match_string(child, "compatible", 82 "register-bit-led") < 0) 83 continue; 84 85 sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL); 86 if (!sled) 87 return -ENOMEM; 88 89 sled->map = map; 90 91 if (of_property_read_u32(child, "offset", &sled->offset)) 92 return -EINVAL; 93 if (of_property_read_u32(child, "mask", &sled->mask)) 94 return -EINVAL; 95 sled->cdev.name = 96 of_get_property(child, "label", NULL) ? : child->name; 97 sled->cdev.default_trigger = 98 of_get_property(child, "linux,default-trigger", NULL); 99 100 state = of_get_property(child, "default-state", NULL); 101 if (state) { 102 if (!strcmp(state, "keep")) { 103 u32 val; 104 105 ret = regmap_read(map, sled->offset, &val); 106 if (ret < 0) 107 return ret; 108 sled->state = !!(val & sled->mask); 109 } else if (!strcmp(state, "on")) { 110 sled->state = true; 111 ret = regmap_update_bits(map, sled->offset, 112 sled->mask, 113 sled->mask); 114 if (ret < 0) 115 return ret; 116 } else { 117 sled->state = false; 118 ret = regmap_update_bits(map, sled->offset, 119 sled->mask, 0); 120 if (ret < 0) 121 return ret; 122 } 123 } 124 sled->cdev.brightness_set = syscon_led_set; 125 126 ret = led_classdev_register(dev, &sled->cdev); 127 if (ret < 0) 128 return ret; 129 130 dev_info(dev, "registered LED %s\n", sled->cdev.name); 131 } 132 return 0; 133 } 134 135 static int __init syscon_leds_init(void) 136 { 137 struct device_node *np; 138 139 for_each_of_allnodes(np) { 140 struct platform_device *pdev; 141 struct regmap *map; 142 int ret; 143 144 if (!of_device_is_compatible(np, "syscon")) 145 continue; 146 147 map = syscon_node_to_regmap(np); 148 if (IS_ERR(map)) { 149 pr_err("error getting regmap for syscon LEDs\n"); 150 continue; 151 } 152 153 /* 154 * If the map is there, the device should be there, we allocate 155 * memory on the syscon device's behalf here. 156 */ 157 pdev = of_find_device_by_node(np); 158 if (!pdev) 159 return -ENODEV; 160 ret = syscon_leds_spawn(np, &pdev->dev, map); 161 if (ret) 162 dev_err(&pdev->dev, "could not spawn syscon LEDs\n"); 163 } 164 165 return 0; 166 } 167 device_initcall(syscon_leds_init); 168