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 #ifdef CONFIG_CPU_BIG_ENDIAN
  53         iowrite32be(data, reg);
  54 #else
  55         writel(data, reg);
  56 #endif
  57 }
  58
  59 static unsigned long bcm6358_led_read(void __iomem *reg)
  60 {
  61 #ifdef CONFIG_CPU_BIG_ENDIAN
  62         return ioread32be(reg);
  63 #else
  64         return readl(reg);
  65 #endif
  66 }
  67
  68 static unsigned long bcm6358_led_busy(void __iomem *mem)
  69 {
  70         unsigned long val;
  71
  72         while ((val = bcm6358_led_read(mem + BCM6358_REG_CTRL)) &
  73                 BCM6358_SLED_BUSY)
  74                 udelay(BCM6358_SLED_WAIT);
  75
  76         return val;
  77 }
  78
  79 static void bcm6358_led_set(struct led_classdev *led_cdev,
  80                             enum led_brightness value)
  81 {
  82         struct bcm6358_led *led =
  83                 container_of(led_cdev, struct bcm6358_led, cdev);
  84         unsigned long flags, val;
  85
  86         spin_lock_irqsave(led->lock, flags);
  87         bcm6358_led_busy(led->mem);
  88         val = bcm6358_led_read(led->mem + BCM6358_REG_MODE);
  89         if ((led->active_low && value == LED_OFF) ||
  90             (!led->active_low && value != LED_OFF))
  91                 val |= BIT(led->pin);
  92         else
  93                 val &= ~(BIT(led->pin));
  94         bcm6358_led_write(led->mem + BCM6358_REG_MODE, val);
  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         const char *state;
 103         int rc;
 104
 105         led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
 106         if (!led)
 107                 return -ENOMEM;
 108
 109         led->pin = reg;
 110         led->mem = mem;
 111         led->lock = lock;
 112
 113         if (of_property_read_bool(nc, "active-low"))
 114                 led->active_low = true;
 115
 116         led->cdev.name = of_get_property(nc, "label", NULL) ? : nc->name;
 117         led->cdev.default_trigger = of_get_property(nc,
 118                                                     "linux,default-trigger",
 119                                                     NULL);
 120
 121         if (!of_property_read_string(nc, "default-state", &state)) {
 122                 if (!strcmp(state, "on")) {
 123                         led->cdev.brightness = LED_FULL;
 124                 } else if (!strcmp(state, "keep")) {
 125                         unsigned long val;
 126                         val = bcm6358_led_read(led->mem + BCM6358_REG_MODE);
 127                         val &= BIT(led->pin);
 128                         if ((led->active_low && !val) ||
 129                             (!led->active_low && val))
 130                                 led->cdev.brightness = LED_FULL;
 131                         else
 132                                 led->cdev.brightness = LED_OFF;
 133                 } else {
 134                         led->cdev.brightness = LED_OFF;
 135                 }
 136         } else {
 137                 led->cdev.brightness = LED_OFF;
 138         }
 139
 140         bcm6358_led_set(&led->cdev, led->cdev.brightness);
 141
 142         led->cdev.brightness_set = bcm6358_led_set;
 143
 144         rc = led_classdev_register(dev, &led->cdev);
 145         if (rc < 0)
 146                 return rc;
 147
 148         dev_dbg(dev, "registered LED %s\n", led->cdev.name);
 149
 150         return 0;
 151 }
 152
 153 static int bcm6358_leds_probe(struct platform_device *pdev)
 154 {
 155         struct device *dev = &pdev->dev;
 156         struct device_node *np = pdev->dev.of_node;
 157         struct device_node *child;
 158         struct resource *mem_r;
 159         void __iomem *mem;
 160         spinlock_t *lock; /* memory lock */
 161         unsigned long val;
 162         u32 clk_div;
 163
 164         mem_r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 165         if (!mem_r)
 166                 return -EINVAL;
 167
 168         mem = devm_ioremap_resource(dev, mem_r);
 169         if (IS_ERR(mem))
 170                 return PTR_ERR(mem);
 171
 172         lock = devm_kzalloc(dev, sizeof(*lock), GFP_KERNEL);
 173         if (!lock)
 174                 return -ENOMEM;
 175
 176         spin_lock_init(lock);
 177
 178         val = bcm6358_led_busy(mem);
 179         val &= ~(BCM6358_SLED_POLARITY | BCM6358_SLED_CLKDIV_MASK);
 180         if (of_property_read_bool(np, "brcm,clk-dat-low"))
 181                 val |= BCM6358_SLED_POLARITY;
 182         of_property_read_u32(np, "brcm,clk-div", &clk_div);
 183         switch (clk_div) {
 184         case 8:
 185                 val |= BCM6358_SLED_CLKDIV_8;
 186                 break;
 187         case 4:
 188                 val |= BCM6358_SLED_CLKDIV_4;
 189                 break;
 190         case 2:
 191                 val |= BCM6358_SLED_CLKDIV_2;
 192                 break;
 193         default:
 194                 val |= BCM6358_SLED_CLKDIV_1;
 195                 break;
 196         }
 197         bcm6358_led_write(mem + BCM6358_REG_CTRL, val);
 198
 199         for_each_available_child_of_node(np, child) {
 200                 int rc;
 201                 u32 reg;
 202
 203                 if (of_property_read_u32(child, "reg", &reg))
 204                         continue;
 205
 206                 if (reg >= BCM6358_SLED_MAX_COUNT) {
 207                         dev_err(dev, "invalid LED (%u >= %d)\n", reg,
 208                                 BCM6358_SLED_MAX_COUNT);
 209                         continue;
 210                 }
 211
 212                 rc = bcm6358_led(dev, child, reg, mem, lock);
 213                 if (rc < 0) {
 214                         of_node_put(child);
 215                         return rc;
 216                 }
 217         }
 218
 219         return 0;
 220 }
 221
 222 static const struct of_device_id bcm6358_leds_of_match[] = {
 223         { .compatible = "brcm,bcm6358-leds", },
 224         { },
 225 };
 226 MODULE_DEVICE_TABLE(of, bcm6358_leds_of_match);
 227
 228 static struct platform_driver bcm6358_leds_driver = {
 229         .probe = bcm6358_leds_probe,
 230         .driver = {
 231                 .name = "leds-bcm6358",
 232                 .of_match_table = bcm6358_leds_of_match,
 233         },
 234 };
 235
 236 module_platform_driver(bcm6358_leds_driver);
 237
 238 MODULE_AUTHOR("Álvaro Fernández Rojas <noltari@gmail.com>");
 239 MODULE_DESCRIPTION("LED driver for BCM6358 controllers");
 240 MODULE_LICENSE("GPL v2");
 241 MODULE_ALIAS("platform:leds-bcm6358");