Date:	Fri,  8 Aug 2014 18:12:35 +0900
From:	Gyungoh Yoo <gyungoh@...il.com>
To:	rdunlap@...radead.org, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, jg1.han@...sung.com, cooloney@...il.com,
	lee.jones@...aro.org, plagnioj@...osoft.com, tomi.valkeinen@...com
Cc:	jack.yoo@...worksinc.com, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-fbdev@...r.kernel.org
Subject: [PATCH 3/3] Adding Skyworks SKY81452 backlight driver

Signed-off-by: Gyungoh Yoo <jack.yoo@...worksinc.com>
---
 Documentation/backlight/sky81452-backlight.txt     |  26 ++
 .../video/backlight/sky81452-backlight.txt         |  20 ++
 drivers/video/backlight/Kconfig                    |  10 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/sky81452-backlight.c       | 334 +++++++++++++++++++++
 include/linux/sky81452-backlight.h                 |  47 +++
 6 files changed, 438 insertions(+)
 create mode 100644 Documentation/backlight/sky81452-backlight.txt
 create mode 100644 Documentation/devicetree/bindings/video/backlight/sky81452-backlight.txt
 create mode 100644 drivers/video/backlight/sky81452-backlight.c
 create mode 100644 include/linux/sky81452-backlight.h

diff --git a/Documentation/backlight/sky81452-backlight.txt b/Documentation/backlight/sky81452-backlight.txt
new file mode 100644
index 0000000..e5a18ee
--- /dev/null
+++ b/Documentation/backlight/sky81452-backlight.txt
@@ -0,0 +1,26 @@
+backlight driver for sky81452
+==========================
+
+* Skyworks Solutions SKY81452 :
+  High-Efficiency, Six-Channel White LED Driver with Touch Panel Bias Supply
+
+Description
+-----------
+The SKY81452 is a highly integrated, high-efficiency LED backlight solution for
+tablets, notebook computers, monitors, and other portable devices.
+
+The SKY81452 supports Direct Pulse Width Modulation(DPWM) dimming and Analog
+Pulse Width Modulation (APWM). In the DPWM dimming mode, the output waveform
+follows the Pulse Width Modulation Input(PWMI) signal and the current level is
+set by I2C control and an external RSET resistor. In the APWM mode, the PWMI
+signal duty and the I2C brightness control signal are multiplied to control
+the output current level.
+
+The driver exports some additional attributes for SKY81452.
+- enable : Current sink channels. Bit0 is for channel 1, Bit1 is for channel 2
+	and Bit2 is for channel 3. In same way, Bit5 is for channel 6.
+	For example, if 5 is written to this attribute, channel 1 and
+	channel 3 are enabled.
+- open : Shows an open LED fault.
+- short : Shows an short LED fault.
+- fault : Shows information about over-current and over-temperature.
diff --git a/Documentation/devicetree/bindings/video/backlight/sky81452-backlight.txt b/Documentation/devicetree/bindings/video/backlight/sky81452-backlight.txt
new file mode 100644
index 0000000..ebedc33
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/backlight/sky81452-backlight.txt
@@ -0,0 +1,20 @@
+SKY81452-backlight bindings
+
+Optional properties:
+- name			: Name of backlight device. Default is 'lcd-backlight'.
+- gpio-enable		: GPIO to use to EN pin.
+- enable		: Enable mask for current sink channel 1 to 6.
+- ignore-pwm		: Ignore both PWM input
+- dpwm-mode		: Enable DPWM dimming mode, otherwise Analog dimming mode
+- phase-shift		: Enable phase shift mode
+- ovp-level		: Over-voltage protection level. Should be between 14 or 28V.
+- short-detection-threshold : It should be one of 4, 5, 6 and 7V.
+- boost-current-limit	: It should be one of 800, 1100 and 1500mA.
+
+Example:
+
+	backlight {
+		name = "pwm-backlight";
+		enable = <0x3F>;
+		ignore-pwm;
+	};
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index cc153f5..7b92a1b 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -420,6 +420,16 @@ config BACKLIGHT_PANDORA
 	  If you have a Pandora console, say Y to enable the
 	  backlight driver.
 
+config BACKLIGHT_SKY81452
+	tristate "Backlight driver for SKY81452"
+	depends on BACKLIGHT_CLASS_DEVICE && SKY81452
+	help
+	  If you have a Skyworks SKY81452, say Y to enable the
+	  backlight driver.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called sky81452-backlight
+
 config BACKLIGHT_TPS65217
 	tristate "TPS65217 Backlight"
 	depends on BACKLIGHT_CLASS_DEVICE && MFD_TPS65217
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index a9ea34a..7e8136f 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_BACKLIGHT_PANDORA)		+= pandora_bl.o
 obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
 obj-$(CONFIG_BACKLIGHT_PWM)		+= pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
+obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
diff --git a/drivers/video/backlight/sky81452-backlight.c b/drivers/video/backlight/sky81452-backlight.c
new file mode 100644
index 0000000..d14179d
--- /dev/null
+++ b/drivers/video/backlight/sky81452-backlight.c
@@ -0,0 +1,334 @@
+/*
+ * sky81452-backlight.c	SKY81452 backlight driver
+ *
+ * Copyright 2014 Skyworks Solutions Inc.
+ * Author : Gyungoh Yoo <jack.yoo@...worksinc.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/regmap.h>
+#include <linux/backlight.h>
+#include <linux/sky81452-backlight.h>
+
+/* registers */
+#define SKY81452_REG0	0x00
+#define SKY81452_REG1	0x01
+#define SKY81452_REG2	0x02
+#define SKY81452_REG4	0x04
+#define SKY81452_REG5	0x05
+
+/* bit mask */
+#define SKY81452_CS	0xFF
+#define SKY81452_EN	0x3F
+#define SKY81452_IGPW	0x20
+#define SKY81452_PWMMD	0x10
+#define SKY81452_PHASE	0x08
+#define SKY81452_ILIM	0x04
+#define SKY81452_VSHRT	0x03
+#define SKY81452_OCP	0x80
+#define SKY81452_OTMP	0x40
+#define SKY81452_SHRT	0x3F
+#define SKY81452_OPN	0x3F
+
+#define SKY81452_DEFAULT_NAME "lcd-backlight"
+#define SKY81452_MAX_BRIGHTNESS	(SKY81452_CS + 1)
+
+/* count trailing zeros */
+#define CTZ(b) ((b) & 0x0F ? \
+	((b) & 0x03 ? ((b) & 0x01 ? 0 : 1) : ((b) & 0x04 ? 2 : 3)) : \
+	((b) & 0x30 ? ((b) & 0x10 ? 4 : 5) : ((b) & 0x40 ? 6 : 7)))
+
+static int sky81452_bl_update_status(struct backlight_device *bd)
+{
+	const struct sky81452_bl_platform_data *pdata =
+			dev_get_platdata(bd->dev.parent);
+	const unsigned int brightness = (unsigned int)bd->props.brightness;
+	struct regmap *map = bl_get_data(bd);
+	int ret;
+
+	if (brightness == 0)
+		return regmap_update_bits(map, SKY81452_REG1, SKY81452_EN, 0);
+	else {
+		ret = regmap_write(map, SKY81452_REG0, brightness - 1);
+		if (IS_ERR_VALUE(ret))
+			return ret;
+
+		return regmap_update_bits(map, SKY81452_REG1, SKY81452_EN,
+				pdata->enable << CTZ(SKY81452_EN));
+	}
+}
+
+static int sky81452_bl_get_brightness(struct backlight_device *bd)
+{
+	return bd->props.brightness;
+}
+
+static const struct backlight_ops sky81452_bl_ops = {
+	.update_status = sky81452_bl_update_status,
+	.get_brightness = sky81452_bl_get_brightness,
+};
+
+static ssize_t sky81452_bl_store_enable(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct regmap *map = bl_get_data(to_backlight_device(dev));
+	unsigned long value;
+	int ret;
+
+	ret = kstrtoul(buf, 16, &value);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+
+	ret = regmap_update_bits(map, SKY81452_REG1,
+			SKY81452_EN, value << CTZ(SKY81452_EN));
+	if (IS_ERR_VALUE(ret))
+		return ret;
+
+	return count;
+}
+
+static ssize_t sky81452_bl_show_open_short(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct regmap *map = bl_get_data(to_backlight_device(dev));
+	unsigned int reg, value = 0;
+	char tmp[3];
+	int i, ret;
+
+	reg = !strcmp(attr->attr.name, "open") ? SKY81452_REG5 : SKY81452_REG4;
+	ret = regmap_read(map, reg, &value);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+
+	if (value & SKY81452_SHRT) {
+		*buf = 0;
+		for (i = 0; i < 6; i++) {
+			if (value & 0x01) {
+				sprintf(tmp, "%d ", i + 1);
+				strcat(buf, tmp);
+			}
+			value >>= 1;
+		}
+		strcat(buf, "\n");
+	} else
+		strcpy(buf, "none\n");
+
+	return strlen(buf);
+}
+
+static ssize_t sky81452_bl_show_fault(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct regmap *map = bl_get_data(to_backlight_device(dev));
+	unsigned int value = 0;
+	int ret;
+
+	ret = regmap_read(map, SKY81452_REG4, &value);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+
+	*buf = 0;
+
+	if (value & SKY81452_OCP)
+		strcat(buf, "over-current ");
+
+	if (value & SKY81452_OTMP)
+		strcat(buf, "over-temperature");
+
+	strcat(buf, "\n");
+	return strlen(buf);
+}
+
+static DEVICE_ATTR(enable, S_IWGRP | S_IWUSR, NULL, sky81452_bl_store_enable);
+static DEVICE_ATTR(open, S_IRUGO, sky81452_bl_show_open_short, NULL);
+static DEVICE_ATTR(short, S_IRUGO, sky81452_bl_show_open_short, NULL);
+static DEVICE_ATTR(fault, S_IRUGO, sky81452_bl_show_fault, NULL);
+
+static struct attribute *sky81452_bl_attribute[] = {
+	&dev_attr_enable.attr,
+	&dev_attr_open.attr,
+	&dev_attr_short.attr,
+	&dev_attr_fault.attr,
+	NULL
+};
+
+static const struct attribute_group sky81452_bl_attr_group = {
+	.attrs = sky81452_bl_attribute,
+};
+
+#ifdef CONFIG_OF
+static struct sky81452_bl_platform_data *sky81452_bl_parse_dt
+		(struct device *dev)
+{
+	struct device_node *np = dev->parent->of_node;
+	struct sky81452_bl_platform_data *pdata;
+	int ret;
+
+	np = of_get_child_by_name(dev->parent->of_node, "backlight");
+	if (unlikely(!np)) {
+		dev_err(dev, "backlight node not found");
+		return ERR_PTR(-EINVAL);
+	}
+
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (unlikely(!pdata)) {
+		of_node_put(np);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	of_property_read_string(np, "name", &pdata->name);
+	pdata->ignore_pwm = of_property_read_bool(np, "ignore-pwm");
+	pdata->dpwm_mode = of_property_read_bool(np, "dpwm-mode");
+	pdata->phase_shift = of_property_read_bool(np, "phase-shift");
+
+	pdata->gpio_enable = of_get_named_gpio(np, "gpio-enable", 0);
+	if (IS_ERR_VALUE(pdata->gpio_enable))
+		pdata->gpio_enable = -1;
+
+	ret = of_property_read_u32(np, "enable", &pdata->enable);
+	if (IS_ERR_VALUE(ret))
+		pdata->enable = SKY81452_EN >> CTZ(SKY81452_EN);
+
+	ret = of_property_read_u32(np, "short-detection-threshold",
+			&pdata->short_detection_threshold);
+	if (IS_ERR_VALUE(ret))
+		pdata->short_detection_threshold = 7;
+
+	ret = of_property_read_u32(np, "boost-current-limit",
+			&pdata->boost_current_limit);
+	if (IS_ERR_VALUE(ret))
+		pdata->boost_current_limit = 2750;
+
+	of_node_put(np);
+	return pdata;
+}
+#else
+static struct sky81452_bl_platform_data *sky81452_bl_parse_dt
+		(struct device *dev)
+{
+	return ERR_PTR(-EINVAL);
+}
+#endif
+
+static int sky81452_bl_init_device(struct regmap *map,
+		struct sky81452_bl_platform_data *pdata)
+{
+	unsigned int value;
+
+	value = pdata->ignore_pwm ? SKY81452_IGPW : 0;
+	value |= pdata->dpwm_mode ? SKY81452_PWMMD : 0;
+	value |= pdata->phase_shift ? 0 : SKY81452_PHASE;
+
+	if (pdata->boost_current_limit == 2300)
+		value |= SKY81452_ILIM;
+	else if (pdata->boost_current_limit != 2720)
+		return -EINVAL;
+
+	if (pdata->short_detection_threshold < 4 ||
+			pdata->short_detection_threshold > 7)
+		return -EINVAL;
+	value |= (7 - pdata->short_detection_threshold) << CTZ(SKY81452_VSHRT);
+
+	return regmap_write(map, SKY81452_REG2, value);
+}
+
+static int sky81452_bl_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct regmap *map = dev_get_drvdata(dev->parent);
+	struct sky81452_bl_platform_data *pdata = dev_get_platdata(dev);
+	struct backlight_device *bd;
+	struct backlight_properties props;
+	const char *name;
+	int ret;
+
+	if (!pdata) {
+		pdata = sky81452_bl_parse_dt(dev);
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+	}
+
+	if (pdata->gpio_enable >= 0) {
+		ret = devm_gpio_request_one(dev, pdata->gpio_enable,
+				GPIOF_OUT_INIT_HIGH, "sky81452-en");
+		if (IS_ERR_VALUE(ret))
+			return ret;
+	}
+
+	ret = sky81452_bl_init_device(map, pdata);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+
+	memset(&props, 0, sizeof(props));
+	props.max_brightness = SKY81452_MAX_BRIGHTNESS,
+	name = pdata->name ? pdata->name : SKY81452_DEFAULT_NAME;
+	bd = devm_backlight_device_register(dev, name,
+			dev, map, &sky81452_bl_ops, &props);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	platform_set_drvdata(pdev, bd);
+
+	ret  = sysfs_create_group(&bd->dev.kobj, &sky81452_bl_attr_group);
+	if (IS_ERR_VALUE(ret))
+		goto err;
+
+	return ret;
+err:
+	backlight_device_unregister(bd);
+	return ret;
+}
+
+static int sky81452_bl_remove(struct platform_device *pdev)
+{
+	const struct sky81452_bl_platform_data *pdata =
+			dev_get_platdata(&pdev->dev);
+	struct backlight_device *bd = platform_get_drvdata(pdev);
+
+	sysfs_remove_group(&bd->dev.kobj, &sky81452_bl_attr_group);
+
+	bd->props.power = FB_BLANK_UNBLANK;
+	bd->props.brightness = 0;
+	backlight_update_status(bd);
+
+	if (pdata->gpio_enable >= 0)
+		gpio_set_value_cansleep(pdata->gpio_enable, 0);
+
+	return 0;
+}
+
+static struct platform_driver sky81452_bl_driver = {
+	.driver = {
+		.name = "sky81452-bl",
+	},
+	.probe = sky81452_bl_probe,
+	.remove = sky81452_bl_remove,
+};
+
+module_platform_driver(sky81452_bl_driver);
+
+MODULE_DESCRIPTION("Skyworks SKY81452 backlight driver");
+MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@...worksinc.com>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0");
diff --git a/include/linux/sky81452-backlight.h b/include/linux/sky81452-backlight.h
new file mode 100644
index 0000000..b3635f9
--- /dev/null
+++ b/include/linux/sky81452-backlight.h
@@ -0,0 +1,47 @@
+/*
+ * sky81452.h	SKY81452 backlight driver
+ *
+ * Copyright 2014 Skyworks Solutions Inc.
+ * Author : Gyungoh Yoo <jack.yoo@...worksinc.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _SKY81452_BACKLIGHT_H
+#define _SKY81452_BACKLIGHT_H
+
+/**
+ * struct sky81452_platform_data
+ * @name:	backlight driver name.
+		If it is not defined, default name is lcd-backlight.
+ * @gpio_enable:GPIO number which control EN pin
+ * @enable:	Enable mask for current sink channel 1, 2, 3, 4, 5 and 6.
+ * @ignore_pwm:	true if DPWMI should be ignored.
+ * @dpwm_mode:	true is DPWM dimming mode, otherwise Analog dimming mode.
+ * @phase_shift:true is phase shift mode.
+ * @short_detecion_threshold:	It should be one of 4, 5, 6 and 7V.
+ * @boost_current_limit:	It should be one of 2300, 2750mA.
+ */
+struct sky81452_bl_platform_data {
+	const char *name;
+	int gpio_enable;
+	unsigned int enable;
+	bool ignore_pwm;
+	bool dpwm_mode;
+	bool phase_shift;
+	unsigned int short_detection_threshold;
+	unsigned int boost_current_limit;
+};
+
+#endif
-- 
1.9.1

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