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.h> 11 #include <linux/platform_device.h> 12 #include <linux/stat.h> 13 #include <linux/slab.h> 14 #include <linux/mfd/syscon.h> 15 #include <linux/regmap.h> 16 #include <linux/leds.h> 17 18 /** 19 * struct syscon_led - state container for syscon based LEDs 20 * @cdev: LED class device for this LED 21 * @map: regmap to access the syscon device backing this LED 22 * @offset: the offset into the syscon regmap for the LED register 23 * @mask: the bit in the register corresponding to the LED 24 * @state: current state of the LED 25 */ 26 struct syscon_led { 27 struct led_classdev cdev; 28 struct regmap *map; 29 u32 offset; 30 u32 mask; 31 bool state; 32 }; 33 34 static void syscon_led_set(struct led_classdev *led_cdev, 35 enum led_brightness value) 36 { 37 struct syscon_led *sled = 38 container_of(led_cdev, struct syscon_led, cdev); 39 u32 val; 40 int ret; 41 42 if (value == LED_OFF) { 43 val = 0; 44 sled->state = false; 45 } else { 46 val = sled->mask; 47 sled->state = true; 48 } 49 50 ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val); 51 if (ret < 0) 52 dev_err(sled->cdev.dev, "error updating LED status\n"); 53 } 54 55 static int syscon_led_probe(struct platform_device *pdev) 56 { 57 struct led_init_data init_data = {}; 58 struct device *dev = &pdev->dev; 59 struct device_node *np = dev_of_node(dev); 60 struct device *parent; 61 struct regmap *map; 62 struct syscon_led *sled; 63 enum led_default_state state; 64 u32 value; 65 int ret; 66 67 parent = dev->parent; 68 if (!parent) { 69 dev_err(dev, "no parent for syscon LED\n"); 70 return -ENODEV; 71 } 72 map = syscon_node_to_regmap(dev_of_node(parent)); 73 if (IS_ERR(map)) { 74 dev_err(dev, "no regmap for syscon LED parent\n"); 75 return PTR_ERR(map); 76 } 77 78 sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL); 79 if (!sled) 80 return -ENOMEM; 81 82 sled->map = map; 83 84 if (of_property_read_u32(np, "offset", &sled->offset)) 85 return -EINVAL; 86 if (of_property_read_u32(np, "mask", &sled->mask)) 87 return -EINVAL; 88 89 init_data.fwnode = of_fwnode_handle(np); 90 91 state = led_init_default_state_get(init_data.fwnode); 92 switch (state) { 93 case LEDS_DEFSTATE_ON: 94 ret = regmap_update_bits(map, sled->offset, sled->mask, sled->mask); 95 if (ret < 0) 96 return ret; 97 sled->state = true; 98 break; 99 case LEDS_DEFSTATE_KEEP: 100 ret = regmap_read(map, sled->offset, &value); 101 if (ret < 0) 102 return ret; 103 sled->state = !!(value & sled->mask); 104 break; 105 default: 106 ret = regmap_update_bits(map, sled->offset, sled->mask, 0); 107 if (ret < 0) 108 return ret; 109 sled->state = false; 110 } 111 sled->cdev.brightness_set = syscon_led_set; 112 113 ret = devm_led_classdev_register_ext(dev, &sled->cdev, &init_data); 114 if (ret < 0) 115 return ret; 116 117 platform_set_drvdata(pdev, sled); 118 dev_info(dev, "registered LED %s\n", sled->cdev.name); 119 120 return 0; 121 } 122 123 static const struct of_device_id of_syscon_leds_match[] = { 124 { .compatible = "register-bit-led", }, 125 {}, 126 }; 127 128 static struct platform_driver syscon_led_driver = { 129 .probe = syscon_led_probe, 130 .driver = { 131 .name = "leds-syscon", 132 .of_match_table = of_syscon_leds_match, 133 .suppress_bind_attrs = true, 134 }, 135 }; 136 builtin_platform_driver(syscon_led_driver); 137