drivers/video/backlight/max8925_bl.c

   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
  27 struct max8925_backlight_data {
  28         struct max8925_chip     *chip;
  29
  30         int     current_brightness;
  31         int     reg_mode_cntl;
  32         int     reg_cntl;
  33 };
  34
  35 static 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;
  62 out:
  63         dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
  64                 value, ret);
  65         return ret;
  66 }
  67
  68 static 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
  84 static 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
  98 static 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
 104 static 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_find_node_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         pdev->dev.platform_data = pdata;
 129 }
 130
 131 static int max8925_backlight_probe(struct platform_device *pdev)
 132 {
 133         struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
 134         struct max8925_backlight_pdata *pdata;
 135         struct max8925_backlight_data *data;
 136         struct backlight_device *bl;
 137         struct backlight_properties props;
 138         struct resource *res;
 139         unsigned char value;
 140         int ret = 0;
 141
 142         data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
 143                             GFP_KERNEL);
 144         if (data == NULL)
 145                 return -ENOMEM;
 146
 147         res = platform_get_resource(pdev, IORESOURCE_REG, 0);
 148         if (!res) {
 149                 dev_err(&pdev->dev, "No REG resource for mode control!\n");
 150                 return -ENXIO;
 151         }
 152         data->reg_mode_cntl = res->start;
 153         res = platform_get_resource(pdev, IORESOURCE_REG, 1);
 154         if (!res) {
 155                 dev_err(&pdev->dev, "No REG resource for control!\n");
 156                 return -ENXIO;
 157         }
 158         data->reg_cntl = res->start;
 159
 160         data->chip = chip;
 161         data->current_brightness = 0;
 162
 163         memset(&props, 0, sizeof(struct backlight_properties));
 164         props.type = BACKLIGHT_RAW;
 165         props.max_brightness = MAX_BRIGHTNESS;
 166         bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
 167                                         &pdev->dev, data,
 168                                         &max8925_backlight_ops, &props);
 169         if (IS_ERR(bl)) {
 170                 dev_err(&pdev->dev, "failed to register backlight\n");
 171                 return PTR_ERR(bl);
 172         }
 173         bl->props.brightness = MAX_BRIGHTNESS;
 174
 175         platform_set_drvdata(pdev, bl);
 176
 177         value = 0;
 178         if (!pdev->dev.platform_data)
 179                 max8925_backlight_dt_init(pdev);
 180
 181         pdata = pdev->dev.platform_data;
 182         if (pdata) {
 183                 if (pdata->lxw_scl)
 184                         value |= (1 << 7);
 185                 if (pdata->lxw_freq)
 186                         value |= (LWX_FREQ(pdata->lxw_freq) << 4);
 187                 if (pdata->dual_string)
 188                         value |= (1 << 1);
 189         }
 190         ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
 191         if (ret < 0)
 192                 return ret;
 193         backlight_update_status(bl);
 194         return 0;
 195 }
 196
 197 static struct platform_driver max8925_backlight_driver = {
 198         .driver         = {
 199                 .name   = "max8925-backlight",
 200         },
 201         .probe          = max8925_backlight_probe,
 202 };
 203
 204 module_platform_driver(max8925_backlight_driver);
 205
 206 MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
 207 MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
 208 MODULE_LICENSE("GPL");
 209 MODULE_ALIAS("platform:max8925-backlight");