leds: Added driver for the NXP PCA9685 I2C chip

The NXP PCA9685 supports 16 channels/leds using a 12-bit PWM (4095
levels of brightness)
This driver supports configuration using platform_data.
Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/Kconfig

@@ -300,6 +300,16 @@ config LEDS_PCA963X
 	  LED driver chip accessed via the I2C bus. Supported
 	  devices include PCA9633 and PCA9634
 
+config LEDS_PCA9685
+	tristate "LED support for PCA9685 I2C chip"
+	depends on LEDS_CLASS
+	depends on I2C
+	help
+	  This option enables support for LEDs connected to the PCA9685
+	  LED driver chip accessed via the I2C bus.
+	  The PCA9685 offers 12-bit PWM (4095 levels of brightness) on
+	  16 individual channels.
+
 config LEDS_WM831X_STATUS
 	tristate "LED support for status LEDs on WM831x PMICs"
 	depends on LEDS_CLASS

drivers/leds/Makefile

@@ -36,6 +36,7 @@ obj-$(CONFIG_LEDS_OT200)		+= leds-ot200.o
 obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o
 obj-$(CONFIG_LEDS_PCA955X)		+= leds-pca955x.o
 obj-$(CONFIG_LEDS_PCA963X)		+= leds-pca963x.o
+obj-$(CONFIG_LEDS_PCA9685)		+= leds-pca9685.o
 obj-$(CONFIG_LEDS_DA903X)		+= leds-da903x.o
 obj-$(CONFIG_LEDS_DA9052)		+= leds-da9052.o
 obj-$(CONFIG_LEDS_WM831X_STATUS)	+= leds-wm831x-status.o

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");

include/linux/platform_data/leds-pca9685.h

+/*
+ * 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.h by Peter Meerwald <p.meerwald@bct-electronic.com>
+ *
+ * LED driver for the NXP PCA9685 PWM chip
+ *
+ */
+
+#ifndef __LINUX_PCA9685_H
+#define __LINUX_PCA9685_H
+
+#include <linux/leds.h>
+
+enum pca9685_outdrv {
+	PCA9685_OPEN_DRAIN,
+	PCA9685_TOTEM_POLE,
+};
+
+enum pca9685_inverted {
+	PCA9685_NOT_INVERTED,
+	PCA9685_INVERTED,
+};
+
+struct pca9685_platform_data {
+	struct led_platform_data leds;
+	enum pca9685_outdrv outdrv;
+	enum pca9685_inverted inverted;
+};
+
+#endif /* __LINUX_PCA9685_H */