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>

4 files changed, 410 insertions, 0 deletions

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index efb09046a8cf..2d9923a60076 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 fcd50b732165..d67073f9d421 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 000000000000..052fa1bac03d
--- /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");
diff --git a/include/linux/platform_data/sky81452-backlight.h b/include/linux/platform_data/sky81452-backlight.h
new file mode 100644
index 000000000000..1231e9bb00f1
--- /dev/null
+++ b/include/linux/platform_data/sky81452-backlight.h
@@ -0,0 +1,46 @@
+/*
+ * sky81452.h   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/>.
+ */
+
+#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