backlight: Add support Skyworks SKY81452 backlight driver

Signed-off-by: Gyungoh Yoo <jack.yoo@skyworksinc.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Bryan Wu <cooloney@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

3 files changed, 364 insertions, 0 deletions

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index efb0904..2d9923a 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -408,6 +408,16 @@ 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 && MFD_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 fcd50b73..d67073f 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -50,6 +50,7 @@ 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..052fa1b
--- /dev/null
+++ b/drivers/video/backlight/sky81452-backlight.c
@@ -0,0 +1,353 @@
+/*
+ * sky81452-backlight.c	SKY81452 backlight driver
+ *
+ * Copyright 2014 Skyworks Solutions Inc.
+ * Author : Gyungoh Yoo <jack.yoo@skyworksinc.com>
+ *
+ * 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.
+ *
+ * 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/backlight.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/platform_data/sky81452-backlight.h>
+#include <linux/slab.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)
+
+#define CTZ(b) __builtin_ctz(b)
+
+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 *regmap = bl_get_data(bd);
+	int ret;
+
+	if (brightness > 0) {
+		ret = regmap_write(regmap, SKY81452_REG0, brightness - 1);
+		if (IS_ERR_VALUE(ret))
+			return ret;
+
+		return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
+					pdata->enable << CTZ(SKY81452_EN));
+	}
+
+	return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN, 0);
+}
+
+static const struct backlight_ops sky81452_bl_ops = {
+	.update_status = sky81452_bl_update_status,
+};
+
+static ssize_t sky81452_bl_store_enable(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct regmap *regmap = 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(regmap, 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 *regmap = 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(regmap, 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 *regmap = bl_get_data(to_backlight_device(dev));
+	unsigned int value = 0;
+	int ret;
+
+	ret = regmap_read(regmap, 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 = of_node_get(dev->of_node);
+	struct sky81452_bl_platform_data *pdata;
+	int num_entry;
+	unsigned int sources[6];
+	int ret;
+
+	if (!np) {
+		dev_err(dev, "backlight node not found.\n");
+		return ERR_PTR(-ENODATA);
+	}
+
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!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, "skyworks,ignore-pwm");
+	pdata->dpwm_mode = of_property_read_bool(np, "skyworks,dpwm-mode");
+	pdata->phase_shift = of_property_read_bool(np, "skyworks,phase-shift");
+	pdata->gpio_enable = of_get_gpio(np, 0);
+
+	ret = of_property_count_u32_elems(np, "led-sources");
+	if (IS_ERR_VALUE(ret)) {
+		pdata->enable = SKY81452_EN >> CTZ(SKY81452_EN);
+	} else {
+		num_entry = ret;
+		if (num_entry > 6)
+			num_entry = 6;
+
+		ret = of_property_read_u32_array(np, "led-sources", sources,
+					num_entry);
+		if (IS_ERR_VALUE(ret)) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return ERR_PTR(-EINVAL);
+		}
+
+		pdata->enable = 0;
+		while (--num_entry)
+			pdata->enable |= (1 << sources[num_entry]);
+	}
+
+	ret = of_property_read_u32(np,
+			"skyworks,short-detection-threshold-volt",
+			&pdata->short_detection_threshold);
+	if (IS_ERR_VALUE(ret))
+		pdata->short_detection_threshold = 7;
+
+	ret = of_property_read_u32(np, "skyworks,current-limit-mA",
+			&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 *regmap,
+		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 != 2750)
+		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(regmap, SKY81452_REG2, value);
+}
+
+static int sky81452_bl_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct regmap *regmap = 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 (gpio_is_valid(pdata->gpio_enable)) {
+		ret = devm_gpio_request_one(dev, pdata->gpio_enable,
+					GPIOF_OUT_INIT_HIGH, "sky81452-en");
+		if (IS_ERR_VALUE(ret)) {
+			dev_err(dev, "failed to request GPIO. err=%d\n", ret);
+			return ret;
+		}
+	}
+
+	ret = sky81452_bl_init_device(regmap, pdata);
+	if (IS_ERR_VALUE(ret)) {
+		dev_err(dev, "failed to initialize. err=%d\n", 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, regmap,
+						&sky81452_bl_ops, &props);
+	if (IS_ERR(bd)) {
+		dev_err(dev, "failed to register. err=%ld\n", PTR_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)) {
+		dev_err(dev, "failed to create attribute. err=%d\n", ret);
+		return ret;
+	}
+
+	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 (gpio_is_valid(pdata->gpio_enable))
+		gpio_set_value_cansleep(pdata->gpio_enable, 0);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id sky81452_bl_of_match[] = {
+	{ .compatible = "skyworks,sky81452-backlight", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sky81452_bl_of_match);
+#endif
+
+static struct platform_driver sky81452_bl_driver = {
+	.driver = {
+		.name = "sky81452-backlight",
+		.of_match_table = of_match_ptr(sky81452_bl_of_match),
+	},
+	.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@skyworksinc.com>");
+MODULE_LICENSE("GPL v2");