linux/drivers/video/backlight/max8925_bl.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Backlight driver for Maxim MAX8925
   4 *
   5 * Copyright (C) 2009 Marvell International Ltd.
   6 *      Haojian Zhuang <haojian.zhuang@marvell.com>
   7 */
   8
   9#include <linux/init.h>
  10#include <linux/kernel.h>
  11#include <linux/platform_device.h>
  12#include <linux/fb.h>
  13#include <linux/i2c.h>
  14#include <linux/backlight.h>
  15#include <linux/mfd/max8925.h>
  16#include <linux/slab.h>
  17#include <linux/module.h>
  18
  19#define MAX_BRIGHTNESS          (0xff)
  20#define MIN_BRIGHTNESS          (0)
  21
  22#define LWX_FREQ(x)             (((x - 601) / 100) & 0x7)
  23
  24struct max8925_backlight_data {
  25        struct max8925_chip     *chip;
  26
  27        int     current_brightness;
  28        int     reg_mode_cntl;
  29        int     reg_cntl;
  30};
  31
  32static int max8925_backlight_set(struct backlight_device *bl, int brightness)
  33{
  34        struct max8925_backlight_data *data = bl_get_data(bl);
  35        struct max8925_chip *chip = data->chip;
  36        unsigned char value;
  37        int ret;
  38
  39        if (brightness > MAX_BRIGHTNESS)
  40                value = MAX_BRIGHTNESS;
  41        else
  42                value = brightness;
  43
  44        ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
  45        if (ret < 0)
  46                goto out;
  47
  48        if (!data->current_brightness && brightness)
  49                /* enable WLED output */
  50                ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
  51        else if (!brightness)
  52                /* disable WLED output */
  53                ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
  54        if (ret < 0)
  55                goto out;
  56        dev_dbg(chip->dev, "set brightness %d\n", value);
  57        data->current_brightness = value;
  58        return 0;
  59out:
  60        dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
  61                value, ret);
  62        return ret;
  63}
  64
  65static int max8925_backlight_update_status(struct backlight_device *bl)
  66{
  67        return max8925_backlight_set(bl, backlight_get_brightness(bl));
  68}
  69
  70static int max8925_backlight_get_brightness(struct backlight_device *bl)
  71{
  72        struct max8925_backlight_data *data = bl_get_data(bl);
  73        struct max8925_chip *chip = data->chip;
  74        int ret;
  75
  76        ret = max8925_reg_read(chip->i2c, data->reg_cntl);
  77        if (ret < 0)
  78                return -EINVAL;
  79        data->current_brightness = ret;
  80        dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
  81        return ret;
  82}
  83
  84static const struct backlight_ops max8925_backlight_ops = {
  85        .options        = BL_CORE_SUSPENDRESUME,
  86        .update_status  = max8925_backlight_update_status,
  87        .get_brightness = max8925_backlight_get_brightness,
  88};
  89
  90static void max8925_backlight_dt_init(struct platform_device *pdev)
  91{
  92        struct device_node *nproot = pdev->dev.parent->of_node, *np;
  93        struct max8925_backlight_pdata *pdata;
  94        u32 val;
  95
  96        if (!nproot || !IS_ENABLED(CONFIG_OF))
  97                return;
  98
  99        pdata = devm_kzalloc(&pdev->dev,
 100                             sizeof(struct max8925_backlight_pdata),
 101                             GFP_KERNEL);
 102        if (!pdata)
 103                return;
 104
 105        np = of_get_child_by_name(nproot, "backlight");
 106        if (!np) {
 107                dev_err(&pdev->dev, "failed to find backlight node\n");
 108                return;
 109        }
 110
 111        if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
 112                pdata->dual_string = val;
 113
 114        of_node_put(np);
 115
 116        pdev->dev.platform_data = pdata;
 117}
 118
 119static int max8925_backlight_probe(struct platform_device *pdev)
 120{
 121        struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
 122        struct max8925_backlight_pdata *pdata;
 123        struct max8925_backlight_data *data;
 124        struct backlight_device *bl;
 125        struct backlight_properties props;
 126        struct resource *res;
 127        unsigned char value;
 128        int ret = 0;
 129
 130        data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
 131                            GFP_KERNEL);
 132        if (data == NULL)
 133                return -ENOMEM;
 134
 135        res = platform_get_resource(pdev, IORESOURCE_REG, 0);
 136        if (!res) {
 137                dev_err(&pdev->dev, "No REG resource for mode control!\n");
 138                return -ENXIO;
 139        }
 140        data->reg_mode_cntl = res->start;
 141        res = platform_get_resource(pdev, IORESOURCE_REG, 1);
 142        if (!res) {
 143                dev_err(&pdev->dev, "No REG resource for control!\n");
 144                return -ENXIO;
 145        }
 146        data->reg_cntl = res->start;
 147
 148        data->chip = chip;
 149        data->current_brightness = 0;
 150
 151        memset(&props, 0, sizeof(struct backlight_properties));
 152        props.type = BACKLIGHT_RAW;
 153        props.max_brightness = MAX_BRIGHTNESS;
 154        bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
 155                                        &pdev->dev, data,
 156                                        &max8925_backlight_ops, &props);
 157        if (IS_ERR(bl)) {
 158                dev_err(&pdev->dev, "failed to register backlight\n");
 159                return PTR_ERR(bl);
 160        }
 161        bl->props.brightness = MAX_BRIGHTNESS;
 162
 163        platform_set_drvdata(pdev, bl);
 164
 165        value = 0;
 166        if (!pdev->dev.platform_data)
 167                max8925_backlight_dt_init(pdev);
 168
 169        pdata = pdev->dev.platform_data;
 170        if (pdata) {
 171                if (pdata->lxw_scl)
 172                        value |= (1 << 7);
 173                if (pdata->lxw_freq)
 174                        value |= (LWX_FREQ(pdata->lxw_freq) << 4);
 175                if (pdata->dual_string)
 176                        value |= (1 << 1);
 177        }
 178        ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
 179        if (ret < 0)
 180                return ret;
 181        backlight_update_status(bl);
 182        return 0;
 183}
 184
 185static struct platform_driver max8925_backlight_driver = {
 186        .driver         = {
 187                .name   = "max8925-backlight",
 188        },
 189        .probe          = max8925_backlight_probe,
 190};
 191
 192module_platform_driver(max8925_backlight_driver);
 193
 194MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
 195MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
 196MODULE_LICENSE("GPL");
 197MODULE_ALIAS("platform:max8925-backlight");
 198