[RFC v4 1/2] backlight: add new tps611xx backlight driver

[Daniel Jeong]

This driver is a general version for tps611xx backlgiht chips of TI.
It supports tps61158, tps61161, tps61163 and tps61165 backlight driver
based on EasyScale protocol(1-Wire Control Interface).

EasyScale
EasyScale is a simple but flexible one pin interface to configure the current.
The interface is based on a master-slave structure, where the master is
typically a microcontroller or application processor and the IC is the slave.
The advantage of EasyScale compared with other one pin interfaces is that
its bit detection is in a large extent independent from the bit transmission
rate. It can automatically detect bit rates between 1.7kBit/sec and up
to 160kBit/sec.

EasyScale on TPS61163
A command consists of 24 bits, including an 8-bit device address byte and
a 16-bit data byte. All of the 24 bits should be transmitted together each
time, and the LSB bit should be transmitted first. The device address byte
A7(MSB)~A0(LSB) is fixed to 0x8F.
The data byte includes 9 bits D8(MSB)~D0(LSB) for brightness information
and an RFA bit. The RFA bit set to "1" indicates the Request for Acknowledge
condition. The Acknowledge condition is only applied when the protocol is
received correctly.
Bit sream : D0-D8 | 0 | RFA | 00000 | A0-A7
Please refer to the links below  for more details.
http://www.ti.com/lit/ds/symlink/tps61163.pdf

EasyScale on TPS61158/61/65
A command consists of 16 bits, including an 8-bit device address byte
and a 8-bit data byte. All of the 16 bits should be transmitted together
each time, and the MSB bit should be transmitted first. The device address
byte A7(MSB)~A0(LSB) is fixed (tps61158 0x58 tps61161 and tps61165 0x72).
The data byte includes an RFA bit.
The RFA bit set to "1" indicates the Request for Acknowledge condition.
The Acknowledge condition is only applied when the protocol is received
correctly.
Bit sream : A7-A0 | RFA | 00 | D4-D0
Please refer to the links below  for more details.
http://www.ti.com/lit/ds/symlink/tps61158.pdf
http://www.ti.com.cn/cn/lit/ds/symlink/tps61161-q1.pdf
http://www.ti.com/lit/ds/symlink/tps61165.pdf

Signed-off-by: Daniel Jeong <gshark.jeong@xxxxxxxxx>
---
 drivers/video/backlight/Kconfig           |    7 +
 drivers/video/backlight/Makefile          |    1 +
 drivers/video/backlight/tps611xx_bl.c     |  479 +++++++++++++++++++++++++++++
 include/linux/platform_data/tps611xx_bl.h |   31 ++
 4 files changed, 518 insertions(+)
 create mode 100644 drivers/video/backlight/tps611xx_bl.c
 create mode 100644 include/linux/platform_data/tps611xx_bl.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5a3eb2e..c779a85 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -418,6 +418,13 @@ config BACKLIGHT_TPS65217
 	  If you have a Texas Instruments TPS65217 say Y to enable the
 	  backlight driver.
 
+config BACKLIGHT_TPS611xx
+	tristate "TPS611xx Backlight"
+	depends on BACKLIGHT_CLASS_DEVICE && GPIOLIB
+	help
+	  This supports TI TPS61158,TPS61161, TPS61163 and TPS61165
+	  backlight driver based on EasyScale Protocol.
+
 config BACKLIGHT_AS3711
 	tristate "AS3711 Backlight"
 	depends on BACKLIGHT_CLASS_DEVICE && MFD_AS3711
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index bb82002..5c39945 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -51,5 +51,6 @@ obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
 obj-$(CONFIG_BACKLIGHT_PWM)		+= pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
+obj-$(CONFIG_BACKLIGHT_TPS611xx)	+= tps611xx_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
diff --git a/drivers/video/backlight/tps611xx_bl.c b/drivers/video/backlight/tps611xx_bl.c
new file mode 100644
index 0000000..6c485ff
--- /dev/null
+++ b/drivers/video/backlight/tps611xx_bl.c
@@ -0,0 +1,479 @@
+/*
+ * Simple driver for Texas Instruments TPS611XX Backlight driver chip
+ *        using EasyScale Interface. It supports TPS61158, TPS61161,
+ *        TPS61163 and TPS61165.
+ *
+ * Copyright (C) 2014 Texas Instruments
+ * Author: Daniel Jeong  <gshark.jeong@xxxxxxxxx>
+ *	       Ldd Mlp <ldd-mlp@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_data/tps611xx_bl.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define CMD_FORWARD 0
+#define CMD_BACKWARD 1
+
+enum tps611xx_id {
+	TPS61158_ID = 0,
+	TPS61161_ID,
+	TPS61163_ID,
+	TPS61165_ID,
+};
+
+/*
+ * easyscale time spec
+ * @es_delay : es delay time(ns)
+ * @es_det   : es detection time(ns)
+ * @start    : start time of data stream(ns)
+ * @eos      : end time of data stream(ns)
+ * @reset    : ic shutdown time(ms)
+ * @logic_1_low : low time high bit(ns)
+ * @logic_0_low : low time low bit(ns)
+ * @ackn        : duation of ack condistion(ns)
+ * @ack_poll    : ack polling duration(ns)
+ */
+struct tps611xx_time {
+	unsigned int es_delay;
+	unsigned int es_det;
+	unsigned int start;
+	unsigned int eos;
+	unsigned int reset;
+	unsigned int logic_1_low;
+	unsigned int logic_0_low;
+	unsigned int ackn;
+	unsigned int ack_poll;
+};
+
+/*
+ * @seq : sequence of data transfer
+ * @size: size of data
+ * @brt_max : max brightness
+ * @brt_bmask : bit mask of dimming bits
+ * @rfa_bmask : bit mask of RFA(Request for Acknowledge condition)
+ */
+struct tps611xx_command {
+	int seq;
+	int size;
+	int brt_max;
+	int brt_bmask;
+	int rfa_bmask;
+};
+
+/*
+ * @id : product id
+ * @name : product name
+ * @addr : device address
+ * @cmd  : es command info
+ * @time : es time info
+ */
+struct tps611xx_esdata {
+	enum tps611xx_id id;
+	char *name;
+	int addr;
+	struct tps611xx_command cmd;
+	struct tps611xx_time time;
+};
+
+struct tps611xx_bl_data {
+	struct device *dev;
+	struct backlight_device *bled;
+	struct tps611xx_platform_data *pdata;
+
+	/*
+	 * @rfa_en : RFA enable (Request for Acknowledge condition)
+	 * @en_gpio: enable pin gpio no.
+	 * @esdata : easyscale data
+	 */
+	int rfa_en;
+	unsigned int en_gpio;
+	const struct tps611xx_esdata *esdata;
+};
+
+static struct tps611xx_esdata tps611xx_info[] = {
+	[TPS61158_ID] = {
+		.id = TPS61158_ID,
+		.name = "tps61158",
+		.addr = 0x5800,
+		.cmd = {
+			.seq = CMD_FORWARD,
+			.size = 16,
+			.brt_max = 31,
+			.brt_bmask = 0x1f,
+			.rfa_bmask = 0x80
+		},
+		.time = {
+			.es_delay = 100000,
+			.es_det = 450000,
+			.start = 3500,
+			.eos = 3500,
+			.reset = 4,
+			.logic_1_low = 5000,
+			.logic_0_low = 15000,
+			.ackn = 900000,
+			.ack_poll = 2000
+		},
+	},
+
+	[TPS61161_ID] = {
+		.id = TPS61161_ID,
+		.name = "tps61161",
+		.addr = 0x7200,
+		.cmd = {
+			.seq = CMD_FORWARD,
+			.size = 16,
+			.brt_max = 31,
+			.brt_bmask = 0x1f,
+			.rfa_bmask = 0x80
+		},
+		.time = {
+			.es_delay = 120000,
+			.es_det = 280000,
+			.start = 2000,
+			.eos = 2000,
+			.reset = 3,
+			.logic_1_low = 3000,
+			.logic_0_low = 7000,
+			.ackn = 512000,
+			.ack_poll = 2000
+		},
+	},
+
+	[TPS61163_ID] = {
+		.id = TPS61163_ID,
+		.name = "tps61163",
+		.addr = 0x8F0000,
+		.cmd = {
+			.seq = CMD_BACKWARD,
+			.size = 24,
+			.brt_max = 511,
+			.brt_bmask = 0x1ff,
+			.rfa_bmask = 0x400
+		},
+		.time = {
+			.es_delay = 100000,
+			.es_det = 260000,
+			.start = 2000,
+			.eos = 2000,
+			.reset = 3,
+			.logic_1_low = 3000,
+			.logic_0_low = 7000,
+			.ackn = 512000,
+			.ack_poll = 2000
+		},
+	},
+
+	[TPS61165_ID] = {
+		.id = TPS61165_ID,
+		.name = "tps61165",
+		.addr = 0x7200,
+		.cmd = {
+			.seq = CMD_FORWARD,
+			.size = 16,
+			.brt_max = 31,
+			.brt_bmask = 0x1f,
+			.rfa_bmask = 0x80
+		},
+		.time = {
+			.es_delay = 120000,
+			.es_det = 280000,
+			.start = 4000,
+			.eos = 4000,
+			.reset = 3,
+			.logic_1_low = 3000,
+			.logic_0_low = 7000,
+			.ackn = 512000,
+			.ack_poll = 2000
+		},
+	},
+};
+
+static int tps611xx_bl_update_status(struct backlight_device *bl)
+{
+	struct tps611xx_bl_data *pchip = bl_get_data(bl);
+	const struct tps611xx_esdata *esdata = pchip->esdata;
+	int data_in, t_low, t_logic, max_bmask;
+	unsigned long flags;
+
+	data_in = esdata->addr | (bl->props.brightness & esdata->cmd.brt_bmask);
+	if (pchip->rfa_en)
+		data_in |= esdata->cmd.rfa_bmask;
+
+	max_bmask = 0x1 << esdata->cmd.size;
+	t_logic = esdata->time.logic_1_low + esdata->time.logic_0_low;
+
+	local_irq_save(flags);
+	/* t_start : 2us high before data byte */
+	gpio_direction_output(pchip->en_gpio, 1);
+	ndelay(esdata->time.start);
+
+	/* forward command transfer */
+	if (esdata->cmd.seq == CMD_FORWARD) {
+		int addr_bmask = max_bmask >> 8;
+
+		for (max_bmask >>= 1; max_bmask > 0x0; max_bmask >>= 1) {
+			if (data_in & max_bmask)
+				t_low = esdata->time.logic_1_low;
+			else
+				t_low = esdata->time.logic_0_low;
+
+			gpio_direction_output(pchip->en_gpio, 0);
+			ndelay(t_low);
+			gpio_direction_output(pchip->en_gpio, 1);
+			ndelay(t_logic - t_low);
+
+			if (max_bmask == addr_bmask) {
+				gpio_direction_output(pchip->en_gpio, 0);
+				/* t_eos : low after address byte */
+				ndelay(esdata->time.eos);
+				gpio_direction_output(pchip->en_gpio, 1);
+				/* t_start : high before data byte */
+				ndelay(esdata->time.start);
+			}
+		}
+	} else {
+		/* backward command tansfer */
+		int bmask;
+
+		for (bmask = 0x01; bmask < max_bmask; bmask <<= 1) {
+			if (data_in & bmask)
+				t_low = esdata->time.logic_1_low;
+			else
+				t_low = esdata->time.logic_0_low;
+
+			gpio_direction_output(pchip->en_gpio, 0);
+			ndelay(t_low);
+			gpio_direction_output(pchip->en_gpio, 1);
+			ndelay(t_logic - t_low);
+		}
+	}
+
+	/*
+	 * t_eos : low after address byte
+	 * t_ackVal is also t_eos
+	 */
+	gpio_direction_output(pchip->en_gpio, 0);
+	ndelay(esdata->time.eos);
+
+	/* RFA management  */
+	if (pchip->rfa_en) {
+		int max_ack_time = esdata->time.ackn;
+		/* set input */
+		gpio_direction_input(pchip->en_gpio);
+		/* read acknowledge from chip */
+		while (max_ack_time > 0) {
+			if (gpio_get_value(pchip->en_gpio) == 0)
+				break;
+			max_ack_time -= esdata->time.ack_poll;
+		}
+		if (max_ack_time <= 0)
+			dev_err(pchip->dev,
+				"easyscale : no ack from %s\n", esdata->name);
+		else
+			ndelay(max_ack_time);
+	}
+	gpio_direction_output(pchip->en_gpio, 1);
+	local_irq_restore(flags);
+
+	return bl->props.brightness;
+}
+
+static const struct backlight_ops tps611xx_bl_ops = {
+	.update_status = tps611xx_bl_update_status,
+};
+
+static ssize_t tps611xx_enable_store(struct device *dev,
+				     struct device_attribute *devAttr,
+				     const char *buf, size_t size)
+{
+	struct tps611xx_bl_data *pchip = dev_get_drvdata(dev);
+	const struct tps611xx_esdata *esdata = pchip->esdata;
+	unsigned long flags;
+	unsigned int input;
+	int ret;
+
+	ret = kstrtouint(buf, 10, &input);
+	if (ret)
+		return -EINVAL;
+
+	local_irq_save(flags);
+	if (input == 0) {
+		/* chip disable */
+		gpio_direction_output(pchip->en_gpio, 0);
+		/* low more than reset ms to reset */
+		mdelay(esdata->time.reset);
+	} else {
+		/* easyscale detection window */
+		gpio_direction_output(pchip->en_gpio, 1);
+		ndelay(esdata->time.es_delay);
+		gpio_direction_output(pchip->en_gpio, 0);
+		ndelay(esdata->time.es_det);
+		gpio_direction_output(pchip->en_gpio, 1);
+	}
+	local_irq_restore(flags);
+
+	return size;
+}
+
+static DEVICE_ATTR(enable, S_IWUSR, NULL, tps611xx_enable_store);
+
+#ifdef CONFIG_OF
+static const struct of_device_id tps611xx_backlight_of_match[] = {
+	{.compatible = "ti,tps61158", .data = &tps611xx_info[TPS61158_ID]},
+	{.compatible = "ti,tps61161", .data = &tps611xx_info[TPS61161_ID]},
+	{.compatible = "ti,tps61163", .data = &tps611xx_info[TPS61163_ID]},
+	{.compatible = "ti,tps61165", .data = &tps611xx_info[TPS61165_ID]},
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, tps611xx_backlight_of_match);
+
+static int tps611xx_backlight_parse_dt(struct tps611xx_bl_data *pchip)
+{
+	struct device *dev = pchip->dev;
+	struct device_node *node = dev->of_node;
+	const struct of_device_id *of_id =
+	    of_match_device(tps611xx_backlight_of_match, dev);
+
+	if (!node)
+		return -ENODEV;
+
+	if (!of_id || !of_id->data) {
+		dev_err(dev, "Failed to find tps611xx chip id\n");
+		return -EFAULT;
+	}
+	pchip->esdata = of_id->data;
+	pchip->rfa_en = of_property_read_bool(node, "rfa-enable");
+	pchip->en_gpio = of_get_named_gpio(node, "es-gpio", 0);
+
+	return 0;
+}
+#else
+static int tps611xx_backlight_parse_dt(struct tps611xx_bl_data *pchip)
+{
+	return -ENODEV;
+}
+#endif
+
+static int tps611xx_backlight_probe(struct platform_device *pdev)
+{
+	struct tps611xx_bl_data *pchip;
+	struct backlight_properties props;
+	const struct tps611xx_esdata *esdata;
+	struct tps611xx_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	unsigned long flags;
+	int ret;
+
+	pchip = devm_kzalloc(&pdev->dev,
+			     sizeof(struct tps611xx_bl_data), GFP_KERNEL);
+	if (pchip == NULL)
+		return -ENOMEM;
+	pchip->dev = &pdev->dev;
+
+	if (pdata == NULL) {
+		ret = tps611xx_backlight_parse_dt(pchip);
+		if (ret < 0)
+			return ret;
+	} else {
+		pchip->rfa_en = pdata->rfa_en;
+		pchip->en_gpio = pdata->en_gpio_num;
+		pchip->esdata = (const struct tps611xx_esdata *)
+		    platform_get_device_id(pdev)->driver_data;
+	}
+	esdata = pchip->esdata;
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.brightness = esdata->cmd.brt_max;
+	props.max_brightness = esdata->cmd.brt_max;
+	props.type = BACKLIGHT_RAW;
+	pchip->bled =
+	    devm_backlight_device_register(pchip->dev, TPS611XX_NAME,
+					   pchip->dev, pchip,
+					   &tps611xx_bl_ops, &props);
+	if (IS_ERR(pchip->bled))
+		return PTR_ERR(pchip->bled);
+
+	/* for enable/disable */
+	ret = device_create_file(&(pchip->bled->dev), &dev_attr_enable);
+	if (ret < 0) {
+		dev_err(pchip->dev, "failed : add sysfs entries\n");
+		return ret;
+	}
+	platform_set_drvdata(pdev, pchip);
+
+	/* EasyScale init */
+	ret = gpio_request_one(pchip->en_gpio, GPIOF_OUT_INIT_HIGH, "tps611xx");
+	if (ret) {
+		device_remove_file(&(pchip->bled->dev), &dev_attr_enable);
+		dev_err(pchip->dev, "failed : get gpio %d\n", pchip->en_gpio);
+		return ret;
+	}
+
+	/*
+	 * ES Detection Window
+	 *   - ES detect delay
+	 *   - ES detect time
+	 */
+	local_irq_save(flags);
+	gpio_direction_output(pchip->en_gpio, 1);
+	ndelay(esdata->time.es_delay);
+	gpio_direction_output(pchip->en_gpio, 0);
+	ndelay(esdata->time.es_det);
+	gpio_direction_output(pchip->en_gpio, 1);
+	local_irq_restore(flags);
+	dev_info(pchip->dev,
+		 "%s EasyScale is initialized\n", pchip->esdata->name);
+	return 0;
+}
+
+static int tps611xx_backlight_remove(struct platform_device *pdev)
+{
+	struct tps611xx_bl_data *pchip = platform_get_drvdata(pdev);
+	const struct tps611xx_esdata *esdata = pchip->esdata;
+
+	device_remove_file(&(pchip->bled->dev), &dev_attr_enable);
+	gpio_direction_output(pchip->en_gpio, 0);
+	mdelay(esdata->time.reset);
+	return 0;
+}
+
+static const struct platform_device_id tps611xx_id_table[] = {
+	{TPS61158_NAME, (unsigned long)&tps611xx_info[TPS61158_ID]},
+	{TPS61161_NAME, (unsigned long)&tps611xx_info[TPS61161_ID]},
+	{TPS61163_NAME, (unsigned long)&tps611xx_info[TPS61163_ID]},
+	{TPS61165_NAME, (unsigned long)&tps611xx_info[TPS61165_ID]},
+	{}
+};
+
+static struct platform_driver tps611xx_backlight_driver = {
+	.driver = {
+		.name = TPS611XX_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(tps611xx_backlight_of_match),
+	},
+	.probe = tps611xx_backlight_probe,
+	.remove = tps611xx_backlight_remove,
+	.id_table = tps611xx_id_table,
+};
+
+module_platform_driver(tps611xx_backlight_driver);
+
+MODULE_DESCRIPTION("EasyScale based tps611xx Backlight Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:tps611xx_bl");
diff --git a/include/linux/platform_data/tps611xx_bl.h b/include/linux/platform_data/tps611xx_bl.h
new file mode 100644
index 0000000..f16b43b
--- /dev/null
+++ b/include/linux/platform_data/tps611xx_bl.h
@@ -0,0 +1,31 @@
+/*
+ * Simple driver for Texas Instruments TPS611xx Backlight driver chip
+ * Copyright (C) 2014 Texas Instruments
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __TPS611XX_H
+#define __TPS611XX_H
+
+#define TPS611XX_NAME "tps611xx"
+#define TPS61158_NAME "tps61158"
+#define TPS61161_NAME "tps61161"
+#define TPS61163_NAME "tps61163"
+#define TPS61165_NAME "tps61165"
+
+/*
+ * struct tps611xx platform data
+ * @rfa_en : request for acknowledge
+ * @en_gpio_num : gpio number for en_pin
+ */
+struct tps611xx_platform_data {
+
+	int rfa_en;
+	unsigned int en_gpio_num;
+};
+
+#endif /* __TPS611XX_H */
-- 
1.7.9.5

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