--- /dev/null
+/*
+ * 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;
+};
+
+static 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 const struct backlight_ops lp8788_bl_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = lp8788_bl_update_status,
+};
+
+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);
+
+ return 0;
+}
+
+static struct platform_driver lp8788_bl_driver = {
+ .probe = lp8788_backlight_probe,
+ .remove = lp8788_backlight_remove,
+ .driver = {
+ .name = LP8788_DEV_BACKLIGHT,
+ },
+};
+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");
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