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 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 = devm_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);