/*
* 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);
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");
