drivers/leds/leds-syscon.c

   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 led_init_data init_data = {};
  59         struct device *dev = &pdev->dev;
  60         struct device_node *np = dev_of_node(dev);
  61         struct device *parent;
  62         struct regmap *map;
  63         struct syscon_led *sled;
  64         const char *state;
  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         state = of_get_property(np, "default-state", NULL);
  90         if (state) {
  91                 if (!strcmp(state, "keep")) {
  92                         u32 val;
  93
  94                         ret = regmap_read(map, sled->offset, &val);
  95                         if (ret < 0)
  96                                 return ret;
  97                         sled->state = !!(val & sled->mask);
  98                 } else if (!strcmp(state, "on")) {
  99                         sled->state = true;
 100                         ret = regmap_update_bits(map, sled->offset,
 101                                                  sled->mask,
 102                                                  sled->mask);
 103                         if (ret < 0)
 104                                 return ret;
 105                 } else {
 106                         sled->state = false;
 107                         ret = regmap_update_bits(map, sled->offset,
 108                                                  sled->mask, 0);
 109                         if (ret < 0)
 110                                 return ret;
 111                 }
 112         }
 113         sled->cdev.brightness_set = syscon_led_set;
 114
 115         init_data.fwnode = of_fwnode_handle(np);
 116
 117         ret = devm_led_classdev_register_ext(dev, &sled->cdev, &init_data);
 118         if (ret < 0)
 119                 return ret;
 120
 121         platform_set_drvdata(pdev, sled);
 122         dev_info(dev, "registered LED %s\n", sled->cdev.name);
 123
 124         return 0;
 125 }
 126
 127 static const struct of_device_id of_syscon_leds_match[] = {
 128         { .compatible = "register-bit-led", },
 129         {},
 130 };
 131
 132 static struct platform_driver syscon_led_driver = {
 133         .probe          = syscon_led_probe,
 134         .driver         = {
 135                 .name   = "leds-syscon",
 136                 .of_match_table = of_syscon_leds_match,
 137                 .suppress_bind_attrs = true,
 138         },
 139 };
 140 builtin_platform_driver(syscon_led_driver);