linux/drivers/video/backlight/max8925_bl.c
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   1/*
   2 * Backlight driver for Maxim MAX8925
   3 *
   4 * Copyright (C) 2009 Marvell International Ltd.
   5 *      Haojian Zhuang <haojian.zhuang@marvell.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#include <linux/init.h>
  13#include <linux/kernel.h>
  14#include <linux/platform_device.h>
  15#include <linux/fb.h>
  16#include <linux/i2c.h>
  17#include <linux/backlight.h>
  18#include <linux/mfd/max8925.h>
  19#include <linux/slab.h>
  20#include <linux/module.h>
  21
  22#define MAX_BRIGHTNESS          (0xff)
  23#define MIN_BRIGHTNESS          (0)
  24
  25#define LWX_FREQ(x)             (((x - 601) / 100) & 0x7)
  26
  27struct max8925_backlight_data {
  28        struct max8925_chip     *chip;
  29
  30        int     current_brightness;
  31        int     reg_mode_cntl;
  32        int     reg_cntl;
  33};
  34
  35static int max8925_backlight_set(struct backlight_device *bl, int brightness)
  36{
  37        struct max8925_backlight_data *data = bl_get_data(bl);
  38        struct max8925_chip *chip = data->chip;
  39        unsigned char value;
  40        int ret;
  41
  42        if (brightness > MAX_BRIGHTNESS)
  43                value = MAX_BRIGHTNESS;
  44        else
  45                value = brightness;
  46
  47        ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
  48        if (ret < 0)
  49                goto out;
  50
  51        if (!data->current_brightness && brightness)
  52                /* enable WLED output */
  53                ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
  54        else if (!brightness)
  55                /* disable WLED output */
  56                ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
  57        if (ret < 0)
  58                goto out;
  59        dev_dbg(chip->dev, "set brightness %d\n", value);
  60        data->current_brightness = value;
  61        return 0;
  62out:
  63        dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
  64                value, ret);
  65        return ret;
  66}
  67
  68static int max8925_backlight_update_status(struct backlight_device *bl)
  69{
  70        int brightness = bl->props.brightness;
  71
  72        if (bl->props.power != FB_BLANK_UNBLANK)
  73                brightness = 0;
  74
  75        if (bl->props.fb_blank != FB_BLANK_UNBLANK)
  76                brightness = 0;
  77
  78        if (bl->props.state & BL_CORE_SUSPENDED)
  79                brightness = 0;
  80
  81        return max8925_backlight_set(bl, brightness);
  82}
  83
  84static int max8925_backlight_get_brightness(struct backlight_device *bl)
  85{
  86        struct max8925_backlight_data *data = bl_get_data(bl);
  87        struct max8925_chip *chip = data->chip;
  88        int ret;
  89
  90        ret = max8925_reg_read(chip->i2c, data->reg_cntl);
  91        if (ret < 0)
  92                return -EINVAL;
  93        data->current_brightness = ret;
  94        dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
  95        return ret;
  96}
  97
  98static const struct backlight_ops max8925_backlight_ops = {
  99        .options        = BL_CORE_SUSPENDRESUME,
 100        .update_status  = max8925_backlight_update_status,
 101        .get_brightness = max8925_backlight_get_brightness,
 102};
 103
 104static void max8925_backlight_dt_init(struct platform_device *pdev)
 105{
 106        struct device_node *nproot = pdev->dev.parent->of_node, *np;
 107        struct max8925_backlight_pdata *pdata;
 108        u32 val;
 109
 110        if (!nproot || !IS_ENABLED(CONFIG_OF))
 111                return;
 112
 113        pdata = devm_kzalloc(&pdev->dev,
 114                             sizeof(struct max8925_backlight_pdata),
 115                             GFP_KERNEL);
 116        if (!pdata)
 117                return;
 118
 119        np = of_get_child_by_name(nproot, "backlight");
 120        if (!np) {
 121                dev_err(&pdev->dev, "failed to find backlight node\n");
 122                return;
 123        }
 124
 125        if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
 126                pdata->dual_string = val;
 127
 128        of_node_put(np);
 129
 130        pdev->dev.platform_data = pdata;
 131}
 132
 133static int max8925_backlight_probe(struct platform_device *pdev)
 134{
 135        struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
 136        struct max8925_backlight_pdata *pdata;
 137        struct max8925_backlight_data *data;
 138        struct backlight_device *bl;
 139        struct backlight_properties props;
 140        struct resource *res;
 141        unsigned char value;
 142        int ret = 0;
 143
 144        data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
 145                            GFP_KERNEL);
 146        if (data == NULL)
 147                return -ENOMEM;
 148
 149        res = platform_get_resource(pdev, IORESOURCE_REG, 0);
 150        if (!res) {
 151                dev_err(&pdev->dev, "No REG resource for mode control!\n");
 152                return -ENXIO;
 153        }
 154        data->reg_mode_cntl = res->start;
 155        res = platform_get_resource(pdev, IORESOURCE_REG, 1);
 156        if (!res) {
 157                dev_err(&pdev->dev, "No REG resource for control!\n");
 158                return -ENXIO;
 159        }
 160        data->reg_cntl = res->start;
 161
 162        data->chip = chip;
 163        data->current_brightness = 0;
 164
 165        memset(&props, 0, sizeof(struct backlight_properties));
 166        props.type = BACKLIGHT_RAW;
 167        props.max_brightness = MAX_BRIGHTNESS;
 168        bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
 169                                        &pdev->dev, data,
 170                                        &max8925_backlight_ops, &props);
 171        if (IS_ERR(bl)) {
 172                dev_err(&pdev->dev, "failed to register backlight\n");
 173                return PTR_ERR(bl);
 174        }
 175        bl->props.brightness = MAX_BRIGHTNESS;
 176
 177        platform_set_drvdata(pdev, bl);
 178
 179        value = 0;
 180        if (!pdev->dev.platform_data)
 181                max8925_backlight_dt_init(pdev);
 182
 183        pdata = pdev->dev.platform_data;
 184        if (pdata) {
 185                if (pdata->lxw_scl)
 186                        value |= (1 << 7);
 187                if (pdata->lxw_freq)
 188                        value |= (LWX_FREQ(pdata->lxw_freq) << 4);
 189                if (pdata->dual_string)
 190                        value |= (1 << 1);
 191        }
 192        ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
 193        if (ret < 0)
 194                return ret;
 195        backlight_update_status(bl);
 196        return 0;
 197}
 198
 199static struct platform_driver max8925_backlight_driver = {
 200        .driver         = {
 201                .name   = "max8925-backlight",
 202        },
 203        .probe          = max8925_backlight_probe,
 204};
 205
 206module_platform_driver(max8925_backlight_driver);
 207
 208MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
 209MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
 210MODULE_LICENSE("GPL");
 211MODULE_ALIAS("platform:max8925-backlight");
 212