1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Generic Syscon LEDs Driver 4 * 5 * Copyright (c) 2014, Linaro Limited 6 * Author: Linus Walleij <linus.walleij@linaro.org> 7 */ 8 #include <linux/io.h> 9 #include <linux/init.h> 10 #include <linux/of_device.h> 11 #include <linux/of_address.h> 12 #include <linux/platform_device.h> 13 #include <linux/stat.h> 14 #include <linux/slab.h> 15 #include <linux/mfd/syscon.h> 16 #include <linux/regmap.h> 17 #include <linux/leds.h> 18 19 /** 20 * struct syscon_led - state container for syscon based LEDs 21 * @cdev: LED class device for this LED 22 * @map: regmap to access the syscon device backing this LED 23 * @offset: the offset into the syscon regmap for the LED register 24 * @mask: the bit in the register corresponding to the LED 25 * @state: current state of the LED 26 */ 27 struct syscon_led { 28 struct led_classdev cdev; 29 struct regmap *map; 30 u32 offset; 31 u32 mask; 32 bool state; 33 }; 34 35 static void syscon_led_set(struct led_classdev *led_cdev, 36 enum led_brightness value) 37 { 38 struct syscon_led *sled = 39 container_of(led_cdev, struct syscon_led, cdev); 40 u32 val; 41 int ret; 42 43 if (value == LED_OFF) { 44 val = 0; 45 sled->state = false; 46 } else { 47 val = sled->mask; 48 sled->state = true; 49 } 50 51 ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val); 52 if (ret < 0) 53 dev_err(sled->cdev.dev, "error updating LED status\n"); 54 } 55 56 static int syscon_led_probe(struct platform_device *pdev) 57 { 58 struct device *dev = &pdev->dev; 59 struct device_node *np = dev->of_node; 60 struct device *parent; 61 struct regmap *map; 62 struct syscon_led *sled; 63 const char *state; 64 int ret; 65 66 parent = dev->parent; 67 if (!parent) { 68 dev_err(dev, "no parent for syscon LED\n"); 69 return -ENODEV; 70 } 71 map = syscon_node_to_regmap(parent->of_node); 72 if (IS_ERR(map)) { 73 dev_err(dev, "no regmap for syscon LED parent\n"); 74 return PTR_ERR(map); 75 } 76 77 sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL); 78 if (!sled) 79 return -ENOMEM; 80 81 sled->map = map; 82 83 if (of_property_read_u32(np, "offset", &sled->offset)) 84 return -EINVAL; 85 if (of_property_read_u32(np, "mask", &sled->mask)) 86 return -EINVAL; 87 sled->cdev.name = 88 of_get_property(np, "label", NULL) ? : np->name; 89 sled->cdev.default_trigger = 90 of_get_property(np, "linux,default-trigger", NULL); 91 92 state = of_get_property(np, "default-state", NULL); 93 if (state) { 94 if (!strcmp(state, "keep")) { 95 u32 val; 96 97 ret = regmap_read(map, sled->offset, &val); 98 if (ret < 0) 99 return ret; 100 sled->state = !!(val & sled->mask); 101 } else if (!strcmp(state, "on")) { 102 sled->state = true; 103 ret = regmap_update_bits(map, sled->offset, 104 sled->mask, 105 sled->mask); 106 if (ret < 0) 107 return ret; 108 } else { 109 sled->state = false; 110 ret = regmap_update_bits(map, sled->offset, 111 sled->mask, 0); 112 if (ret < 0) 113 return ret; 114 } 115 } 116 sled->cdev.brightness_set = syscon_led_set; 117 118 ret = led_classdev_register(dev, &sled->cdev); 119 if (ret < 0) 120 return ret; 121 122 platform_set_drvdata(pdev, sled); 123 dev_info(dev, "registered LED %s\n", sled->cdev.name); 124 125 return 0; 126 } 127 128 static const struct of_device_id of_syscon_leds_match[] = { 129 { .compatible = "register-bit-led", }, 130 {}, 131 }; 132 133 static struct platform_driver syscon_led_driver = { 134 .probe = syscon_led_probe, 135 .driver = { 136 .name = "leds-syscon", 137 .of_match_table = of_syscon_leds_match, 138 .suppress_bind_attrs = true, 139 }, 140 }; 141 builtin_platform_driver(syscon_led_driver); 142