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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * TI LP8788 MFD - backlight driver4 *5 * Copyright 2012 Texas Instruments6 *7 * Author: Milo(Woogyom) Kim <milo.kim@ti.com>8 */9 10#include <linux/backlight.h>11#include <linux/err.h>12#include <linux/mfd/lp8788.h>13#include <linux/module.h>14#include <linux/platform_device.h>15#include <linux/slab.h>16 17/* Register address */18#define LP8788_BL_CONFIG 0x9619#define LP8788_BL_EN BIT(0)20#define LP8788_BL_PWM_INPUT_EN BIT(5)21#define LP8788_BL_FULLSCALE_SHIFT 222#define LP8788_BL_DIM_MODE_SHIFT 123#define LP8788_BL_PWM_POLARITY_SHIFT 624 25#define LP8788_BL_BRIGHTNESS 0x9726 27#define LP8788_BL_RAMP 0x9828#define LP8788_BL_RAMP_RISE_SHIFT 429 30#define MAX_BRIGHTNESS 12731#define DEFAULT_BL_NAME "lcd-backlight"32 33struct lp8788_bl {34 struct lp8788 *lp;35 struct backlight_device *bl_dev;36};37 38static int lp8788_backlight_configure(struct lp8788_bl *bl)39{40 int ret;41 u8 val;42 43 /* Brightness ramp up/down */44 val = (LP8788_RAMP_8192us << LP8788_BL_RAMP_RISE_SHIFT) | LP8788_RAMP_8192us;45 ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);46 if (ret)47 return ret;48 49 /* Fullscale current setting */50 val = (LP8788_FULLSCALE_1900uA << LP8788_BL_FULLSCALE_SHIFT) |51 (LP8788_DIM_EXPONENTIAL << LP8788_BL_DIM_MODE_SHIFT);52 53 /* Brightness control mode */54 val |= LP8788_BL_EN;55 56 return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);57}58 59static int lp8788_bl_update_status(struct backlight_device *bl_dev)60{61 struct lp8788_bl *bl = bl_get_data(bl_dev);62 63 if (bl_dev->props.state & BL_CORE_SUSPENDED)64 bl_dev->props.brightness = 0;65 66 lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, bl_dev->props.brightness);67 68 return 0;69}70 71static const struct backlight_ops lp8788_bl_ops = {72 .options = BL_CORE_SUSPENDRESUME,73 .update_status = lp8788_bl_update_status,74};75 76static int lp8788_backlight_register(struct lp8788_bl *bl)77{78 struct backlight_device *bl_dev;79 struct backlight_properties props;80 81 memset(&props, 0, sizeof(struct backlight_properties));82 props.type = BACKLIGHT_PLATFORM;83 props.max_brightness = MAX_BRIGHTNESS;84 85 /* Initial brightness */86 props.brightness = 0;87 88 /* Backlight device name */89 bl_dev = backlight_device_register(DEFAULT_BL_NAME, bl->lp->dev, bl,90 &lp8788_bl_ops, &props);91 if (IS_ERR(bl_dev))92 return PTR_ERR(bl_dev);93 94 bl->bl_dev = bl_dev;95 96 return 0;97}98 99static void lp8788_backlight_unregister(struct lp8788_bl *bl)100{101 struct backlight_device *bl_dev = bl->bl_dev;102 103 backlight_device_unregister(bl_dev);104}105 106static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,107 struct device_attribute *attr, char *buf)108{109 const char *strmode = "Register based";110 111 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);112}113 114static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);115 116static struct attribute *lp8788_attributes[] = {117 &dev_attr_bl_ctl_mode.attr,118 NULL,119};120 121static const struct attribute_group lp8788_attr_group = {122 .attrs = lp8788_attributes,123};124 125static int lp8788_backlight_probe(struct platform_device *pdev)126{127 struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);128 struct lp8788_bl *bl;129 int ret;130 131 bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);132 if (!bl)133 return -ENOMEM;134 135 bl->lp = lp;136 137 platform_set_drvdata(pdev, bl);138 139 ret = lp8788_backlight_configure(bl);140 if (ret) {141 dev_err(lp->dev, "backlight config err: %d\n", ret);142 goto err_dev;143 }144 145 ret = lp8788_backlight_register(bl);146 if (ret) {147 dev_err(lp->dev, "register backlight err: %d\n", ret);148 goto err_dev;149 }150 151 ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);152 if (ret) {153 dev_err(lp->dev, "register sysfs err: %d\n", ret);154 goto err_sysfs;155 }156 157 backlight_update_status(bl->bl_dev);158 159 return 0;160 161err_sysfs:162 lp8788_backlight_unregister(bl);163err_dev:164 return ret;165}166 167static void lp8788_backlight_remove(struct platform_device *pdev)168{169 struct lp8788_bl *bl = platform_get_drvdata(pdev);170 struct backlight_device *bl_dev = bl->bl_dev;171 172 bl_dev->props.brightness = 0;173 backlight_update_status(bl_dev);174 sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);175 lp8788_backlight_unregister(bl);176}177 178static struct platform_driver lp8788_bl_driver = {179 .probe = lp8788_backlight_probe,180 .remove_new = lp8788_backlight_remove,181 .driver = {182 .name = LP8788_DEV_BACKLIGHT,183 },184};185module_platform_driver(lp8788_bl_driver);186 187MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");188MODULE_AUTHOR("Milo Kim");189MODULE_LICENSE("GPL");190MODULE_ALIAS("platform:lp8788-backlight");191