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/module.h> 24 #include <linux/of_device.h> 25 #include <linux/of_address.h> 26 #include <linux/platform_device.h> 27 #include <linux/stat.h> 28 #include <linux/slab.h> 29 #include <linux/mfd/syscon.h> 30 #include <linux/regmap.h> 31 #include <linux/leds.h> 32 33 /** 34 * struct syscon_led - state container for syscon based LEDs 35 * @cdev: LED class device for this LED 36 * @map: regmap to access the syscon device backing this LED 37 * @offset: the offset into the syscon regmap for the LED register 38 * @mask: the bit in the register corresponding to the LED 39 * @state: current state of the LED 40 */ 41 struct syscon_led { 42 struct led_classdev cdev; 43 struct regmap *map; 44 u32 offset; 45 u32 mask; 46 bool state; 47 }; 48 49 static void syscon_led_set(struct led_classdev *led_cdev, 50 enum led_brightness value) 51 { 52 struct syscon_led *sled = 53 container_of(led_cdev, struct syscon_led, cdev); 54 u32 val; 55 int ret; 56 57 if (value == LED_OFF) { 58 val = 0; 59 sled->state = false; 60 } else { 61 val = sled->mask; 62 sled->state = true; 63 } 64 65 ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val); 66 if (ret < 0) 67 dev_err(sled->cdev.dev, "error updating LED status\n"); 68 } 69 70 static int syscon_led_probe(struct platform_device *pdev) 71 { 72 struct device *dev = &pdev->dev; 73 struct device_node *np = dev->of_node; 74 struct device *parent; 75 struct regmap *map; 76 struct syscon_led *sled; 77 const char *state; 78 int ret; 79 80 parent = dev->parent; 81 if (!parent) { 82 dev_err(dev, "no parent for syscon LED\n"); 83 return -ENODEV; 84 } 85 map = syscon_node_to_regmap(parent->of_node); 86 if (IS_ERR(map)) { 87 dev_err(dev, "no regmap for syscon LED parent\n"); 88 return PTR_ERR(map); 89 } 90 91 sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL); 92 if (!sled) 93 return -ENOMEM; 94 95 sled->map = map; 96 97 if (of_property_read_u32(np, "offset", &sled->offset)) 98 return -EINVAL; 99 if (of_property_read_u32(np, "mask", &sled->mask)) 100 return -EINVAL; 101 sled->cdev.name = 102 of_get_property(np, "label", NULL) ? : np->name; 103 sled->cdev.default_trigger = 104 of_get_property(np, "linux,default-trigger", NULL); 105 106 state = of_get_property(np, "default-state", NULL); 107 if (state) { 108 if (!strcmp(state, "keep")) { 109 u32 val; 110 111 ret = regmap_read(map, sled->offset, &val); 112 if (ret < 0) 113 return ret; 114 sled->state = !!(val & sled->mask); 115 } else if (!strcmp(state, "on")) { 116 sled->state = true; 117 ret = regmap_update_bits(map, sled->offset, 118 sled->mask, 119 sled->mask); 120 if (ret < 0) 121 return ret; 122 } else { 123 sled->state = false; 124 ret = regmap_update_bits(map, sled->offset, 125 sled->mask, 0); 126 if (ret < 0) 127 return ret; 128 } 129 } 130 sled->cdev.brightness_set = syscon_led_set; 131 132 ret = led_classdev_register(dev, &sled->cdev); 133 if (ret < 0) 134 return ret; 135 136 platform_set_drvdata(pdev, sled); 137 dev_info(dev, "registered LED %s\n", sled->cdev.name); 138 139 return 0; 140 } 141 142 static int syscon_led_remove(struct platform_device *pdev) 143 { 144 struct syscon_led *sled = platform_get_drvdata(pdev); 145 146 led_classdev_unregister(&sled->cdev); 147 /* Turn it off */ 148 regmap_update_bits(sled->map, sled->offset, sled->mask, 0); 149 return 0; 150 } 151 152 static const struct of_device_id of_syscon_leds_match[] = { 153 { .compatible = "register-bit-led", }, 154 {}, 155 }; 156 157 MODULE_DEVICE_TABLE(of, of_syscon_leds_match); 158 159 static struct platform_driver syscon_led_driver = { 160 .probe = syscon_led_probe, 161 .remove = syscon_led_remove, 162 .driver = { 163 .name = "leds-syscon", 164 .of_match_table = of_syscon_leds_match, 165 }, 166 }; 167 module_platform_driver(syscon_led_driver); 168