drivers/leds/leds-pca9685.c

/*
 * Copyright 2013 Maximilian Güntner <maximilian.guentner@gmail.com>
 *
 * 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.
 *
 * Based on leds-pca963x.c driver by
 * Peter Meerwald <p.meerwald@bct-electronic.com>
 *
 * Driver for the NXP PCA9685 12-Bit PWM LED driver chip.
 *
 */

#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/workqueue.h>

#include <linux/platform_data/leds-pca9685.h>

/* Register Addresses */
#define PCA9685_MODE1 0x00
#define PCA9685_MODE2 0x01
#define PCA9685_LED0_ON_L 0x06
#define PCA9685_ALL_LED_ON_L 0xFA

/* MODE1 Register */
#define PCA9685_ALLCALL 0x00
#define PCA9685_SLEEP   0x04
#define PCA9685_AI      0x05

/* MODE2 Register */
#define PCA9685_INVRT   0x04
#define PCA9685_OUTDRV  0x02

static const struct i2c_device_id pca9685_id[] = {
	{ "pca9685", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, pca9685_id);

struct pca9685_led {
	struct i2c_client *client;
	struct work_struct work;
	u16 brightness;
	struct led_classdev led_cdev;
	int led_num; /* 0-15 */
	char name[32];
};

static void pca9685_write_msg(struct i2c_client *client, u8 *buf, u8 len)
{
	struct i2c_msg msg = {
		.addr = client->addr,
		.flags = 0x00,
		.len = len,
		.buf = buf
	};
	i2c_transfer(client->adapter, &msg, 1);
}

static void pca9685_all_off(struct i2c_client *client)
{
	u8 i2c_buffer[5] = {PCA9685_ALL_LED_ON_L, 0x00, 0x00, 0x00, 0x10};
	pca9685_write_msg(client, i2c_buffer, 5);
}

static void pca9685_led_work(struct work_struct *work)
{
	struct pca9685_led *pca9685;
	u8 i2c_buffer[5];

	pca9685 = container_of(work, struct pca9685_led, work);
	i2c_buffer[0] = PCA9685_LED0_ON_L + 4 * pca9685->led_num;
	/*
	 * 4095 is the maximum brightness, so we set the ON time to 0x1000
	 * which disables the PWM generator for that LED
	 */
	if (pca9685->brightness == 4095)
		*((__le16 *)(i2c_buffer+1)) = cpu_to_le16(0x1000);
	else
		*((__le16 *)(i2c_buffer+1)) = 0x0000;

	if (pca9685->brightness == 0)
		*((__le16 *)(i2c_buffer+3)) = cpu_to_le16(0x1000);
	else if (pca9685->brightness == 4095)
		*((__le16 *)(i2c_buffer+3)) = 0x0000;
	else
		*((__le16 *)(i2c_buffer+3)) = cpu_to_le16(pca9685->brightness);

	pca9685_write_msg(pca9685->client, i2c_buffer, 5);
}

static void pca9685_led_set(struct led_classdev *led_cdev,
		enum led_brightness value)
{
	struct pca9685_led *pca9685;
	pca9685 = container_of(led_cdev, struct pca9685_led, led_cdev);
	pca9685->brightness = value;

	schedule_work(&pca9685->work);
}

static int pca9685_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
{
	struct pca9685_led *pca9685;
	struct pca9685_platform_data *pdata;
	int err;
	u8 i;

	pdata = dev_get_platdata(&client->dev);
	if (pdata) {
		if (pdata->leds.num_leds < 1 || pdata->leds.num_leds > 15) {
			dev_err(&client->dev, "board info must claim 1-16 LEDs");
			return -EINVAL;
		}
	}

	pca9685 = devm_kzalloc(&client->dev, 16 * sizeof(*pca9685), GFP_KERNEL);
	if (!pca9685)
		return -ENOMEM;

	i2c_set_clientdata(client, pca9685);
	pca9685_all_off(client);

	for (i = 0; i < 16; i++) {
		pca9685[i].client = client;
		pca9685[i].led_num = i;
		pca9685[i].name[0] = '\0';
		if (pdata && i < pdata->leds.num_leds) {
			if (pdata->leds.leds[i].name)
				strncpy(pca9685[i].name,
					pdata->leds.leds[i].name,
					sizeof(pca9685[i].name)-1);
			if (pdata->leds.leds[i].default_trigger)
				pca9685[i].led_cdev.default_trigger =
					pdata->leds.leds[i].default_trigger;
		}
		if (strlen(pca9685[i].name) == 0) {
			/*
			 * Write adapter and address to the name as well.
			 * Otherwise multiple chips attached to one host would
			 * not work.
			 */
			snprintf(pca9685[i].name, sizeof(pca9685[i].name),
					"pca9685:%d:x%.2x:%d",
					client->adapter->nr, client->addr, i);
		}
		pca9685[i].led_cdev.name = pca9685[i].name;
		pca9685[i].led_cdev.max_brightness = 0xfff;
		pca9685[i].led_cdev.brightness_set = pca9685_led_set;

		INIT_WORK(&pca9685[i].work, pca9685_led_work);
		err = led_classdev_register(&client->dev, &pca9685[i].led_cdev);
		if (err < 0)
			goto exit;
	}

	if (pdata)
		i2c_smbus_write_byte_data(client, PCA9685_MODE2,
			pdata->outdrv << PCA9685_OUTDRV |
			pdata->inverted << PCA9685_INVRT);
	else
		i2c_smbus_write_byte_data(client, PCA9685_MODE2,
			PCA9685_TOTEM_POLE << PCA9685_OUTDRV);
	/* Enable Auto-Increment, enable oscillator, ALLCALL/SUBADDR disabled */
	i2c_smbus_write_byte_data(client, PCA9685_MODE1, BIT(PCA9685_AI));

	return 0;

exit:
	while (i--) {
		led_classdev_unregister(&pca9685[i].led_cdev);
		cancel_work_sync(&pca9685[i].work);
	}
	return err;
}

static int pca9685_remove(struct i2c_client *client)
{
	struct pca9685_led *pca9685 = i2c_get_clientdata(client);
	u8 i;

	for (i = 0; i < 16; i++) {
		led_classdev_unregister(&pca9685[i].led_cdev);
		cancel_work_sync(&pca9685[i].work);
	}
	pca9685_all_off(client);
	return 0;
}

static struct i2c_driver pca9685_driver = {
	.driver = {
		.name = "leds-pca9685",
		.owner = THIS_MODULE,
	},
	.probe = pca9685_probe,
	.remove = pca9685_remove,
	.id_table = pca9685_id,
};

module_i2c_driver(pca9685_driver);

MODULE_AUTHOR("Maximilian Güntner <maximilian.guentner@gmail.com>");
MODULE_DESCRIPTION("PCA9685 LED Driver");
MODULE_LICENSE("GPL v2");