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// 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/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 {
struct lp8788 *lp;
struct backlight_device *bl_dev;
};
static int lp8788_backlight_configure(struct lp8788_bl *bl)
{
int ret;
u8 val;
/* Brightness ramp up/down */
val = (LP8788_RAMP_8192us << LP8788_BL_RAMP_RISE_SHIFT) | LP8788_RAMP_8192us;
ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
if (ret)
return ret;
/* Fullscale current setting */
val = (LP8788_FULLSCALE_1900uA << LP8788_BL_FULLSCALE_SHIFT) |
(LP8788_DIM_EXPONENTIAL << LP8788_BL_DIM_MODE_SHIFT);
/* Brightness control mode */
val |= LP8788_BL_EN;
return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
}
static int lp8788_bl_update_status(struct backlight_device *bl_dev)
{
struct lp8788_bl *bl = bl_get_data(bl_dev);
if (bl_dev->props.state & BL_CORE_SUSPENDED)
bl_dev->props.brightness = 0;
lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, bl_dev->props.brightness);
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;
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_PLATFORM;
props.max_brightness = MAX_BRIGHTNESS;
/* Initial brightness */
props.brightness = 0;
/* Backlight device name */
bl_dev = backlight_device_register(DEFAULT_BL_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)
{
const char *strmode = "Register based";
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;
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");
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