1 files changed, 324 insertions, 0 deletions
diff --git a/drivers/video/backlight/lp8788_bl.c b/drivers/video/backlight/lp8788_bl.c
new file mode 100644
index 0000000000..d1a14b0db2
--- /dev/null
+++ b/drivers/video/backlight/lp8788_bl.c
@@ -0,0 +1,324 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI LP8788 MFD - backlight driver
+ *
+ * Copyright 2012 Texas Instruments
+ *
+ * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
+ */
+
+#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;
+
+		/*
+		 * FIXME: pwm_apply_args() should be removed when switching to
+		 * the atomic PWM API.
+		 */
+		pwm_apply_args(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;
+
+	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 void 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);
+}
+
+static struct platform_driver lp8788_bl_driver = {
+	.probe = lp8788_backlight_probe,
+	.remove_new = 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");