drivers/leds/leds-bcm6358.c

   1 /*
   2  * Driver for BCM6358 memory-mapped LEDs, based on leds-syscon.c
   3  *
   4  * Copyright 2015 Álvaro Fernández Rojas <noltari@gmail.com>
   5  *
   6  * This program is free software; you can redistribute  it and/or modify it
   7  * under  the terms of  the GNU General  Public License as published by the
   8  * Free Software Foundation;  either version 2 of the  License, or (at your
   9  * option) any later version.
  10  */
  11 #include <linux/delay.h>
  12 #include <linux/io.h>
  13 #include <linux/leds.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/spinlock.h>
  18
  19 #define BCM6358_REG_MODE                0x0
  20 #define BCM6358_REG_CTRL                0x4
  21
  22 #define BCM6358_SLED_CLKDIV_MASK        3
  23 #define BCM6358_SLED_CLKDIV_1           0
  24 #define BCM6358_SLED_CLKDIV_2           1
  25 #define BCM6358_SLED_CLKDIV_4           2
  26 #define BCM6358_SLED_CLKDIV_8           3
  27
  28 #define BCM6358_SLED_POLARITY           BIT(2)
  29 #define BCM6358_SLED_BUSY               BIT(3)
  30
  31 #define BCM6358_SLED_MAX_COUNT          32
  32 #define BCM6358_SLED_WAIT               100
  33
  34 /**
  35  * struct bcm6358_led - state container for bcm6358 based LEDs
  36  * @cdev: LED class device for this LED
  37  * @mem: memory resource
  38  * @lock: memory lock
  39  * @pin: LED pin number
  40  * @active_low: LED is active low
  41  */
  42 struct bcm6358_led {
  43         struct led_classdev cdev;
  44         void __iomem *mem;
  45         spinlock_t *lock;
  46         unsigned long pin;
  47         bool active_low;
  48 };
  49
  50 static void bcm6358_led_write(void __iomem *reg, unsigned long data)
  51 {
  52         iowrite32be(data, reg);
  53 }
  54
  55 static unsigned long bcm6358_led_read(void __iomem *reg)
  56 {
  57         return ioread32be(reg);
  58 }
  59
  60 static unsigned long bcm6358_led_busy(void __iomem *mem)
  61 {
  62         unsigned long val;
  63
  64         while ((val = bcm6358_led_read(mem + BCM6358_REG_CTRL)) &
  65                 BCM6358_SLED_BUSY)
  66                 udelay(BCM6358_SLED_WAIT);
  67
  68         return val;
  69 }
  70
  71 static void bcm6358_led_mode(struct bcm6358_led *led, unsigned long value)
  72 {
  73         unsigned long val;
  74
  75         bcm6358_led_busy(led->mem);
  76
  77         val = bcm6358_led_read(led->mem + BCM6358_REG_MODE);
  78         if ((led->active_low && value == LED_OFF) ||
  79             (!led->active_low && value != LED_OFF))
  80                 val |= BIT(led->pin);
  81         else
  82                 val &= ~(BIT(led->pin));
  83         bcm6358_led_write(led->mem + BCM6358_REG_MODE, val);
  84 }
  85
  86 static void bcm6358_led_set(struct led_classdev *led_cdev,
  87                             enum led_brightness value)
  88 {
  89         struct bcm6358_led *led =
  90                 container_of(led_cdev, struct bcm6358_led, cdev);
  91         unsigned long flags;
  92
  93         spin_lock_irqsave(led->lock, flags);
  94         bcm6358_led_mode(led, value);
  95         spin_unlock_irqrestore(led->lock, flags);
  96 }
  97
  98 static int bcm6358_led(struct device *dev, struct device_node *nc, u32 reg,
  99                        void __iomem *mem, spinlock_t *lock)
 100 {
 101         struct bcm6358_led *led;
 102         unsigned long flags;
 103         const char *state;
 104         int rc;
 105
 106         led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
 107         if (!led)
 108                 return -ENOMEM;
 109
 110         led->pin = reg;
 111         led->mem = mem;
 112         led->lock = lock;
 113
 114         if (of_property_read_bool(nc, "active-low"))
 115                 led->active_low = true;
 116
 117         led->cdev.name = of_get_property(nc, "label", NULL) ? : nc->name;
 118         led->cdev.default_trigger = of_get_property(nc,
 119                                                     "linux,default-trigger",
 120                                                     NULL);
 121
 122         spin_lock_irqsave(lock, flags);
 123         if (!of_property_read_string(nc, "default-state", &state)) {
 124                 if (!strcmp(state, "on")) {
 125                         led->cdev.brightness = LED_FULL;
 126                 } else if (!strcmp(state, "keep")) {
 127                         unsigned long val;
 128
 129                         bcm6358_led_busy(led->mem);
 130
 131                         val = bcm6358_led_read(led->mem + BCM6358_REG_MODE);
 132                         val &= BIT(led->pin);
 133                         if ((led->active_low && !val) ||
 134                             (!led->active_low && val))
 135                                 led->cdev.brightness = LED_FULL;
 136                         else
 137                                 led->cdev.brightness = LED_OFF;
 138                 } else {
 139                         led->cdev.brightness = LED_OFF;
 140                 }
 141         } else {
 142                 led->cdev.brightness = LED_OFF;
 143         }
 144         bcm6358_led_mode(led, led->cdev.brightness);
 145         spin_unlock_irqrestore(lock, flags);
 146
 147         led->cdev.brightness_set = bcm6358_led_set;
 148
 149         rc = led_classdev_register(dev, &led->cdev);
 150         if (rc < 0)
 151                 return rc;
 152
 153         dev_dbg(dev, "registered LED %s\n", led->cdev.name);
 154
 155         return 0;
 156 }
 157
 158 static int bcm6358_leds_probe(struct platform_device *pdev)
 159 {
 160         struct device *dev = &pdev->dev;
 161         struct device_node *np = pdev->dev.of_node;
 162         struct device_node *child;
 163         struct resource *mem_r;
 164         void __iomem *mem;
 165         spinlock_t *lock; /* memory lock */
 166         unsigned long val;
 167         u32 clk_div;
 168
 169         mem_r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 170         if (!mem_r)
 171                 return -EINVAL;
 172
 173         mem = devm_ioremap_resource(dev, mem_r);
 174         if (IS_ERR(mem))
 175                 return PTR_ERR(mem);
 176
 177         lock = devm_kzalloc(dev, sizeof(*lock), GFP_KERNEL);
 178         if (!lock)
 179                 return -ENOMEM;
 180
 181         spin_lock_init(lock);
 182
 183         val = bcm6358_led_busy(mem);
 184         val &= ~(BCM6358_SLED_POLARITY | BCM6358_SLED_CLKDIV_MASK);
 185         if (of_property_read_bool(np, "brcm,clk-dat-low"))
 186                 val |= BCM6358_SLED_POLARITY;
 187         of_property_read_u32(np, "brcm,clk-div", &clk_div);
 188         switch (clk_div) {
 189         case 8:
 190                 val |= BCM6358_SLED_CLKDIV_8;
 191                 break;
 192         case 4:
 193                 val |= BCM6358_SLED_CLKDIV_4;
 194                 break;
 195         case 2:
 196                 val |= BCM6358_SLED_CLKDIV_2;
 197                 break;
 198         default:
 199                 val |= BCM6358_SLED_CLKDIV_1;
 200                 break;
 201         }
 202         bcm6358_led_write(mem + BCM6358_REG_CTRL, val);
 203
 204         for_each_available_child_of_node(np, child) {
 205                 int rc;
 206                 u32 reg;
 207
 208                 if (of_property_read_u32(child, "reg", &reg))
 209                         continue;
 210
 211                 if (reg >= BCM6358_SLED_MAX_COUNT) {
 212                         dev_err(dev, "invalid LED (%u >= %d)\n", reg,
 213                                 BCM6358_SLED_MAX_COUNT);
 214                         continue;
 215                 }
 216
 217                 rc = bcm6358_led(dev, child, reg, mem, lock);
 218                 if (rc < 0)
 219                         return rc;
 220         }
 221
 222         return 0;
 223 }
 224
 225 static const struct of_device_id bcm6358_leds_of_match[] = {
 226         { .compatible = "brcm,bcm6358-leds", },
 227         { },
 228 };
 229
 230 static struct platform_driver bcm6358_leds_driver = {
 231         .probe = bcm6358_leds_probe,
 232         .driver = {
 233                 .name = "leds-bcm6358",
 234                 .of_match_table = bcm6358_leds_of_match,
 235         },
 236 };
 237
 238 module_platform_driver(bcm6358_leds_driver);
 239
 240 MODULE_AUTHOR("Álvaro Fernández Rojas <noltari@gmail.com>");
 241 MODULE_DESCRIPTION("LED driver for BCM6358 controllers");
 242 MODULE_LICENSE("GPL v2");
 243 MODULE_ALIAS("platform:leds-bcm6358");