alistair23-linux/drivers/leds/leds-dac124s085.c

/*
 * Copyright 2008
 * Guennadi Liakhovetski, DENX Software Engineering, <lg@denx.de>
 *
 * This file is subject to the terms and conditions of version 2 of
 * the GNU General Public License.  See the file COPYING in the main
 * directory of this archive for more details.
 *
 * LED driver for the DAC124S085 SPI DAC
 */

#include <linux/leds.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/spi/spi.h>

struct dac124s085_led {
	struct led_classdev	ldev;
	struct spi_device	*spi;
	int			id;
	int			brightness;
	char			name[sizeof("dac124s085-3")];

	struct mutex		mutex;
	struct work_struct	work;
	spinlock_t		lock;
};

struct dac124s085 {
	struct dac124s085_led leds[4];
};

#define REG_WRITE		(0 << 12)
#define REG_WRITE_UPDATE	(1 << 12)
#define ALL_WRITE_UPDATE	(2 << 12)
#define POWER_DOWN_OUTPUT	(3 << 12)

static void dac124s085_led_work(struct work_struct *work)
{
	struct dac124s085_led *led = container_of(work, struct dac124s085_led,
						  work);
	u16 word;

	mutex_lock(&led->mutex);
	word = cpu_to_le16(((led->id) << 14) | REG_WRITE_UPDATE |
			   (led->brightness & 0xfff));
	spi_write(led->spi, (const u8 *)&word, sizeof(word));
	mutex_unlock(&led->mutex);
}

static void dac124s085_set_brightness(struct led_classdev *ldev,
				      enum led_brightness brightness)
{
	struct dac124s085_led *led = container_of(ldev, struct dac124s085_led,
						  ldev);

	spin_lock(&led->lock);
	led->brightness = brightness;
	schedule_work(&led->work);
	spin_unlock(&led->lock);
}

static int dac124s085_probe(struct spi_device *spi)
{
	struct dac124s085	*dac;
	struct dac124s085_led	*led;
	int i, ret;

	dac = kzalloc(sizeof(*dac), GFP_KERNEL);
	if (!dac)
		return -ENOMEM;

	spi->bits_per_word = 16;

	for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
		led		= dac->leds + i;
		led->id		= i;
		led->brightness	= LED_OFF;
		led->spi	= spi;
		snprintf(led->name, sizeof(led->name), "dac124s085-%d", i);
		spin_lock_init(&led->lock);
		INIT_WORK(&led->work, dac124s085_led_work);
		mutex_init(&led->mutex);
		led->ldev.name = led->name;
		led->ldev.brightness = LED_OFF;
		led->ldev.max_brightness = 0xfff;
		led->ldev.brightness_set = dac124s085_set_brightness;
		ret = led_classdev_register(&spi->dev, &led->ldev);
		if (ret < 0)
			goto eledcr;
	}

	spi_set_drvdata(spi, dac);

	return 0;

eledcr:
	while (i--)
		led_classdev_unregister(&dac->leds[i].ldev);

	spi_set_drvdata(spi, NULL);
	kfree(dac);
	return ret;
}

static int dac124s085_remove(struct spi_device *spi)
{
	struct dac124s085	*dac = spi_get_drvdata(spi);
	int i;

	for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
		led_classdev_unregister(&dac->leds[i].ldev);
		cancel_work_sync(&dac->leds[i].work);
	}

	spi_set_drvdata(spi, NULL);
	kfree(dac);

	return 0;
}

static struct spi_driver dac124s085_driver = {
	.probe		= dac124s085_probe,
	.remove		= dac124s085_remove,
	.driver = {
		.name	= "dac124s085",
		.owner	= THIS_MODULE,
	},
};

static int __init dac124s085_leds_init(void)
{
	return spi_register_driver(&dac124s085_driver);
}

static void __exit dac124s085_leds_exit(void)
{
	spi_unregister_driver(&dac124s085_driver);
}

module_init(dac124s085_leds_init);
module_exit(dac124s085_leds_exit);

MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
MODULE_DESCRIPTION("DAC124S085 LED driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:dac124s085");