drivers/leds/leds-syscon.c

   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);