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leds-ixp4xx-gpio.c

/*
 * IXP4XX GPIO driver LED driver
 *
 * Author: John Bowler <jbowler@acm.org>
 *
 * Copyright (c) 2006 John Bowler
 *
 * Permission is hereby granted, free of charge, to any
 * person obtaining a copy of this software and associated
 * documentation files (the "Software"), to deal in the
 * Software without restriction, including without
 * limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the
 * following conditions:
 *
 * The above copyright notice and this permission notice
 * shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
 * ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
 * SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/leds.h>
#include <asm/arch/hardware.h>

extern spinlock_t gpio_lock;

/* Up to 16 gpio lines are possible. */
#define GPIO_MAX 16
static struct ixp4xxgpioled_device {
      struct led_classdev ancestor;
      int               flags;
} ixp4xxgpioled_devices[GPIO_MAX];

void ixp4xxgpioled_brightness_set(struct led_classdev *pled,
                        enum led_brightness value)
{
      const struct ixp4xxgpioled_device *const ixp4xx_dev =
            container_of(pled, struct ixp4xxgpioled_device, ancestor);
      const u32 gpio_pin = ixp4xx_dev - ixp4xxgpioled_devices;

      if (gpio_pin < GPIO_MAX && ixp4xx_dev->ancestor.name != 0) {
            /* Set or clear the 'gpio_pin' bit according to the style
             * and the required setting (value > 0 == on)
             */
            const int gpio_value =
                  (value > 0) == (ixp4xx_dev->flags != IXP4XX_GPIO_LOW) ?
                        IXP4XX_GPIO_HIGH : IXP4XX_GPIO_LOW;

            {
                  unsigned long flags;
                  spin_lock_irqsave(&gpio_lock, flags);
                  gpio_line_set(gpio_pin, gpio_value);
                  spin_unlock_irqrestore(&gpio_lock, flags);
            }
      }
}

/* LEDs are described in resources, the following iterates over the valid
 * LED resources.
 */
#define for_all_leds(i, pdev) \
      for (i=0; i<pdev->num_resources; ++i) \
            if (pdev->resource[i].start < GPIO_MAX && \
                  pdev->resource[i].name != 0)

/* The following applies 'operation' to each LED from the given platform,
 * the function always returns 0 to allow tail call elimination.
 */
static int apply_to_all_leds(struct platform_device *pdev,
      void (*operation)(struct led_classdev *pled))
{
      int i;

      for_all_leds(i, pdev)
            operation(&ixp4xxgpioled_devices[pdev->resource[i].start].ancestor);
      return 0;
}

#ifdef CONFIG_PM
static int ixp4xxgpioled_suspend(struct platform_device *pdev,
                        pm_message_t state)
{
      return apply_to_all_leds(pdev, led_classdev_suspend);
}

static int ixp4xxgpioled_resume(struct platform_device *pdev)
{
      return apply_to_all_leds(pdev, led_classdev_resume);
}
#endif

static void ixp4xxgpioled_remove_one_led(struct led_classdev *pled)
{
      led_classdev_unregister(pled);
      pled->name = 0;
}

static int ixp4xxgpioled_remove(struct platform_device *pdev)
{
      return apply_to_all_leds(pdev, ixp4xxgpioled_remove_one_led);
}

static int ixp4xxgpioled_probe(struct platform_device *pdev)
{
      /* The board level has to tell the driver where the
       * LEDs are connected - there is no way to find out
       * electrically.  It must also say whether the GPIO
       * lines are active high or active low.
       *
       * To do this read the num_resources (the number of
       * LEDs) and the struct resource (the data for each
       * LED).  The name comes from the resource, and it
       * isn't copied.
       */
      int i;

      for_all_leds(i, pdev) {
            const u8 gpio_pin = pdev->resource[i].start;
            int      rc;

            if (ixp4xxgpioled_devices[gpio_pin].ancestor.name == 0) {
                  unsigned long flags;

                  spin_lock_irqsave(&gpio_lock, flags);
                  gpio_line_config(gpio_pin, IXP4XX_GPIO_OUT);
                  /* The config can, apparently, reset the state,
                   * I suspect the gpio line may be an input and
                   * the config may cause the line to be latched,
                   * so the setting depends on how the LED is
                   * connected to the line (which affects how it
                   * floats if not driven).
                   */
                  gpio_line_set(gpio_pin, IXP4XX_GPIO_HIGH);
                  spin_unlock_irqrestore(&gpio_lock, flags);

                  ixp4xxgpioled_devices[gpio_pin].flags =
                        pdev->resource[i].flags & IORESOURCE_BITS;

                  ixp4xxgpioled_devices[gpio_pin].ancestor.name =
                        pdev->resource[i].name;

                  /* This is how a board manufacturer makes the LED
                   * come on on reset - the GPIO line will be high, so
                   * make the LED light when the line is low...
                   */
                  if (ixp4xxgpioled_devices[gpio_pin].flags != IXP4XX_GPIO_LOW)
                        ixp4xxgpioled_devices[gpio_pin].ancestor.brightness = 100;
                  else
                        ixp4xxgpioled_devices[gpio_pin].ancestor.brightness = 0;

                  ixp4xxgpioled_devices[gpio_pin].ancestor.flags = 0;

                  ixp4xxgpioled_devices[gpio_pin].ancestor.brightness_set =
                        ixp4xxgpioled_brightness_set;

                  ixp4xxgpioled_devices[gpio_pin].ancestor.default_trigger = 0;
            }

            rc = led_classdev_register(&pdev->dev,
                        &ixp4xxgpioled_devices[gpio_pin].ancestor);
            if (rc < 0) {
                  ixp4xxgpioled_devices[gpio_pin].ancestor.name = 0;
                  ixp4xxgpioled_remove(pdev);
                  return rc;
            }
      }

      return 0;
}

static struct platform_driver ixp4xxgpioled_driver = {
      .probe   = ixp4xxgpioled_probe,
      .remove  = ixp4xxgpioled_remove,
#ifdef CONFIG_PM
      .suspend = ixp4xxgpioled_suspend,
      .resume  = ixp4xxgpioled_resume,
#endif
      .driver  = {
            .name = "IXP4XX-GPIO-LED",
      },
};

static int __init ixp4xxgpioled_init(void)
{
      return platform_driver_register(&ixp4xxgpioled_driver);
}

static void __exit ixp4xxgpioled_exit(void)
{
      platform_driver_unregister(&ixp4xxgpioled_driver);
}

module_init(ixp4xxgpioled_init);
module_exit(ixp4xxgpioled_exit);

MODULE_AUTHOR("John Bowler <jbowler@acm.org>");
MODULE_DESCRIPTION("IXP4XX GPIO LED driver");
MODULE_LICENSE("Dual MIT/GPL");

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