1 files changed, 333 insertions, 0 deletions

diff --git a/drivers/video/backlight/lp8788_bl.c b/drivers/video/backlight/lp8788_bl.c
new file mode 100644
index 000000000000..4bb8b4f140cf
--- /dev/null
+++ b/drivers/video/backlight/lp8788_bl.c
@@ -0,0 +1,333 @@
+/*
+ * TI LP8788 MFD - backlight driver
+ *
+ * Copyright 2012 Texas Instruments
+ *
+ * Author: Milo(Woogyom) Kim <milo.kim@ti.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.
+ *
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/mfd/lp8788.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+/* Register address */
+#define LP8788_BL_CONFIG                0x96
+#define LP8788_BL_EN                    BIT(0)
+#define LP8788_BL_PWM_INPUT_EN          BIT(5)
+#define LP8788_BL_FULLSCALE_SHIFT       2
+#define LP8788_BL_DIM_MODE_SHIFT        1
+#define LP8788_BL_PWM_POLARITY_SHIFT    6
+
+#define LP8788_BL_BRIGHTNESS            0x97
+
+#define LP8788_BL_RAMP                  0x98
+#define LP8788_BL_RAMP_RISE_SHIFT       4
+
+#define MAX_BRIGHTNESS                  127
+#define DEFAULT_BL_NAME                 "lcd-backlight"
+
+struct lp8788_bl_config {
+        enum lp8788_bl_ctrl_mode bl_mode;
+        enum lp8788_bl_dim_mode dim_mode;
+        enum lp8788_bl_full_scale_current full_scale;
+        enum lp8788_bl_ramp_step rise_time;
+        enum lp8788_bl_ramp_step fall_time;
+        enum pwm_polarity pwm_pol;
+};
+
+struct lp8788_bl {
+        struct lp8788 *lp;
+        struct backlight_device *bl_dev;
+        struct lp8788_backlight_platform_data *pdata;
+        enum lp8788_bl_ctrl_mode mode;
+        struct pwm_device *pwm;
+};
+
+struct lp8788_bl_config default_bl_config = {
+        .bl_mode    = LP8788_BL_REGISTER_ONLY,
+        .dim_mode   = LP8788_DIM_EXPONENTIAL,
+        .full_scale = LP8788_FULLSCALE_1900uA,
+        .rise_time  = LP8788_RAMP_8192us,
+        .fall_time  = LP8788_RAMP_8192us,
+        .pwm_pol    = PWM_POLARITY_NORMAL,
+};
+
+static inline bool is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)
+{
+        return (mode == LP8788_BL_COMB_PWM_BASED);
+}
+
+static inline bool is_brightness_ctrl_by_register(enum lp8788_bl_ctrl_mode mode)
+{
+        return (mode == LP8788_BL_REGISTER_ONLY ||
+                mode == LP8788_BL_COMB_REGISTER_BASED);
+}
+
+static int lp8788_backlight_configure(struct lp8788_bl *bl)
+{
+        struct lp8788_backlight_platform_data *pdata = bl->pdata;
+        struct lp8788_bl_config *cfg = &default_bl_config;
+        int ret;
+        u8 val;
+
+        /*
+         * Update chip configuration if platform data exists,
+         * otherwise use the default settings.
+         */
+        if (pdata) {
+                cfg->bl_mode    = pdata->bl_mode;
+                cfg->dim_mode   = pdata->dim_mode;
+                cfg->full_scale = pdata->full_scale;
+                cfg->rise_time  = pdata->rise_time;
+                cfg->fall_time  = pdata->fall_time;
+                cfg->pwm_pol    = pdata->pwm_pol;
+        }
+
+        /* Brightness ramp up/down */
+        val = (cfg->rise_time << LP8788_BL_RAMP_RISE_SHIFT) | cfg->fall_time;
+        ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
+        if (ret)
+                return ret;
+
+        /* Fullscale current setting */
+        val = (cfg->full_scale << LP8788_BL_FULLSCALE_SHIFT) |
+                (cfg->dim_mode << LP8788_BL_DIM_MODE_SHIFT);
+
+        /* Brightness control mode */
+        switch (cfg->bl_mode) {
+        case LP8788_BL_REGISTER_ONLY:
+                val |= LP8788_BL_EN;
+                break;
+        case LP8788_BL_COMB_PWM_BASED:
+        case LP8788_BL_COMB_REGISTER_BASED:
+                val |= LP8788_BL_EN | LP8788_BL_PWM_INPUT_EN |
+                        (cfg->pwm_pol << LP8788_BL_PWM_POLARITY_SHIFT);
+                break;
+        default:
+                dev_err(bl->lp->dev, "invalid mode: %d\n", cfg->bl_mode);
+                return -EINVAL;
+        }
+
+        bl->mode = cfg->bl_mode;
+
+        return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
+}
+
+static void lp8788_pwm_ctrl(struct lp8788_bl *bl, int br, int max_br)
+{
+        unsigned int period;
+        unsigned int duty;
+        struct device *dev;
+        struct pwm_device *pwm;
+
+        if (!bl->pdata)
+                return;
+
+        period = bl->pdata->period_ns;
+        duty = br * period / max_br;
+        dev = bl->lp->dev;
+
+        /* request PWM device with the consumer name */
+        if (!bl->pwm) {
+                pwm = devm_pwm_get(dev, LP8788_DEV_BACKLIGHT);
+                if (IS_ERR(pwm)) {
+                        dev_err(dev, "can not get PWM device\n");
+                        return;
+                }
+
+                bl->pwm = pwm;
+        }
+
+        pwm_config(bl->pwm, duty, period);
+        if (duty)
+                pwm_enable(bl->pwm);
+        else
+                pwm_disable(bl->pwm);
+}
+
+static int lp8788_bl_update_status(struct backlight_device *bl_dev)
+{
+        struct lp8788_bl *bl = bl_get_data(bl_dev);
+        enum lp8788_bl_ctrl_mode mode = bl->mode;
+
+        if (bl_dev->props.state & BL_CORE_SUSPENDED)
+                bl_dev->props.brightness = 0;
+
+        if (is_brightness_ctrl_by_pwm(mode)) {
+                int brt = bl_dev->props.brightness;
+                int max = bl_dev->props.max_brightness;
+
+                lp8788_pwm_ctrl(bl, brt, max);
+        } else if (is_brightness_ctrl_by_register(mode)) {
+                u8 brt = bl_dev->props.brightness;
+
+                lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt);
+        }
+
+        return 0;
+}
+
+static int lp8788_bl_get_brightness(struct backlight_device *bl_dev)
+{
+        return bl_dev->props.brightness;
+}
+
+static const struct backlight_ops lp8788_bl_ops = {
+        .options = BL_CORE_SUSPENDRESUME,
+        .update_status = lp8788_bl_update_status,
+        .get_brightness = lp8788_bl_get_brightness,
+};
+
+static int lp8788_backlight_register(struct lp8788_bl *bl)
+{
+        struct backlight_device *bl_dev;
+        struct backlight_properties props;
+        struct lp8788_backlight_platform_data *pdata = bl->pdata;
+        int init_brt;
+        char *name;
+
+        props.type = BACKLIGHT_PLATFORM;
+        props.max_brightness = MAX_BRIGHTNESS;
+
+        /* Initial brightness */
+        if (pdata)
+                init_brt = min_t(int, pdata->initial_brightness,
+                                props.max_brightness);
+        else
+                init_brt = 0;
+
+        props.brightness = init_brt;
+
+        /* Backlight device name */
+        if (!pdata || !pdata->name)
+                name = DEFAULT_BL_NAME;
+        else
+                name = pdata->name;
+
+        bl_dev = backlight_device_register(name, bl->lp->dev, bl,
+                                       &lp8788_bl_ops, &props);
+        if (IS_ERR(bl_dev))
+                return PTR_ERR(bl_dev);
+
+        bl->bl_dev = bl_dev;
+
+        return 0;
+}
+
+static void lp8788_backlight_unregister(struct lp8788_bl *bl)
+{
+        struct backlight_device *bl_dev = bl->bl_dev;
+
+        if (bl_dev)
+                backlight_device_unregister(bl_dev);
+}
+
+static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+        struct lp8788_bl *bl = dev_get_drvdata(dev);
+        enum lp8788_bl_ctrl_mode mode = bl->mode;
+        char *strmode;
+
+        if (is_brightness_ctrl_by_pwm(mode))
+                strmode = "PWM based";
+        else if (is_brightness_ctrl_by_register(mode))
+                strmode = "Register based";
+        else
+                strmode = "Invalid mode";
+
+        return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
+
+static struct attribute *lp8788_attributes[] = {
+        &dev_attr_bl_ctl_mode.attr,
+        NULL,
+};
+
+static const struct attribute_group lp8788_attr_group = {
+        .attrs = lp8788_attributes,
+};
+
+static int lp8788_backlight_probe(struct platform_device *pdev)
+{
+        struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
+        struct lp8788_bl *bl;
+        int ret;
+
+        bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
+        if (!bl)
+                return -ENOMEM;
+
+        bl->lp = lp;
+        if (lp->pdata)
+                bl->pdata = lp->pdata->bl_pdata;
+
+        platform_set_drvdata(pdev, bl);
+
+        ret = lp8788_backlight_configure(bl);
+        if (ret) {
+                dev_err(lp->dev, "backlight config err: %d\n", ret);
+                goto err_dev;
+        }
+
+        ret = lp8788_backlight_register(bl);
+        if (ret) {
+                dev_err(lp->dev, "register backlight err: %d\n", ret);
+                goto err_dev;
+        }
+
+        ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
+        if (ret) {
+                dev_err(lp->dev, "register sysfs err: %d\n", ret);
+                goto err_sysfs;
+        }
+
+        backlight_update_status(bl->bl_dev);
+
+        return 0;
+
+err_sysfs:
+        lp8788_backlight_unregister(bl);
+err_dev:
+        return ret;
+}
+
+static int lp8788_backlight_remove(struct platform_device *pdev)
+{
+        struct lp8788_bl *bl = platform_get_drvdata(pdev);
+        struct backlight_device *bl_dev = bl->bl_dev;
+
+        bl_dev->props.brightness = 0;
+        backlight_update_status(bl_dev);
+        sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
+        lp8788_backlight_unregister(bl);
+        platform_set_drvdata(pdev, NULL);
+
+        return 0;
+}
+
+static struct platform_driver lp8788_bl_driver = {
+        .probe = lp8788_backlight_probe,
+        .remove = lp8788_backlight_remove,
+        .driver = {
+                .name = LP8788_DEV_BACKLIGHT,
+                .owner = THIS_MODULE,
+        },
+};
+module_platform_driver(lp8788_bl_driver);
+
+MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
+MODULE_AUTHOR("Milo Kim");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:lp8788-backlight");