drivers/video/backlight/wm831x_bl.c

   1 /*
   2  * Backlight driver for Wolfson Microelectronics WM831x PMICs
   3  *
   4  * Copyright 2009 Wolfson Microelectonics plc
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/module.h>
  15 #include <linux/fb.h>
  16 #include <linux/backlight.h>
  17 #include <linux/slab.h>
  18
  19 #include <linux/mfd/wm831x/core.h>
  20 #include <linux/mfd/wm831x/pdata.h>
  21 #include <linux/mfd/wm831x/regulator.h>
  22
  23 struct wm831x_backlight_data {
  24         struct wm831x *wm831x;
  25         int isink_reg;
  26         int current_brightness;
  27 };
  28
  29 static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
  30 {
  31         struct wm831x_backlight_data *data = bl_get_data(bl);
  32         struct wm831x *wm831x = data->wm831x;
  33         int power_up = !data->current_brightness && brightness;
  34         int power_down = data->current_brightness && !brightness;
  35         int ret;
  36
  37         if (power_up) {
  38                 /* Enable the ISINK */
  39                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  40                                       WM831X_CS1_ENA, WM831X_CS1_ENA);
  41                 if (ret < 0)
  42                         goto err;
  43
  44                 /* Enable the DC-DC */
  45                 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
  46                                       WM831X_DC4_ENA, WM831X_DC4_ENA);
  47                 if (ret < 0)
  48                         goto err;
  49         }
  50
  51         if (power_down) {
  52                 /* DCDC first */
  53                 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
  54                                       WM831X_DC4_ENA, 0);
  55                 if (ret < 0)
  56                         goto err;
  57
  58                 /* ISINK */
  59                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  60                                       WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
  61                 if (ret < 0)
  62                         goto err;
  63         }
  64
  65         /* Set the new brightness */
  66         ret = wm831x_set_bits(wm831x, data->isink_reg,
  67                               WM831X_CS1_ISEL_MASK, brightness);
  68         if (ret < 0)
  69                 goto err;
  70
  71         if (power_up) {
  72                 /* Drive current through the ISINK */
  73                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  74                                       WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
  75                 if (ret < 0)
  76                         return ret;
  77         }
  78
  79         data->current_brightness = brightness;
  80
  81         return 0;
  82
  83 err:
  84         /* If we were in the middle of a power transition always shut down
  85          * for safety.
  86          */
  87         if (power_up || power_down) {
  88                 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
  89                 wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
  90         }
  91
  92         return ret;
  93 }
  94
  95 static int wm831x_backlight_update_status(struct backlight_device *bl)
  96 {
  97         int brightness = bl->props.brightness;
  98
  99         if (bl->props.power != FB_BLANK_UNBLANK)
 100                 brightness = 0;
 101
 102         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
 103                 brightness = 0;
 104
 105         if (bl->props.state & BL_CORE_SUSPENDED)
 106                 brightness = 0;
 107
 108         return wm831x_backlight_set(bl, brightness);
 109 }
 110
 111 static int wm831x_backlight_get_brightness(struct backlight_device *bl)
 112 {
 113         struct wm831x_backlight_data *data = bl_get_data(bl);
 114         return data->current_brightness;
 115 }
 116
 117 static const struct backlight_ops wm831x_backlight_ops = {
 118         .options = BL_CORE_SUSPENDRESUME,
 119         .update_status  = wm831x_backlight_update_status,
 120         .get_brightness = wm831x_backlight_get_brightness,
 121 };
 122
 123 static int wm831x_backlight_probe(struct platform_device *pdev)
 124 {
 125         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 126         struct wm831x_pdata *wm831x_pdata;
 127         struct wm831x_backlight_pdata *pdata;
 128         struct wm831x_backlight_data *data;
 129         struct backlight_device *bl;
 130         struct backlight_properties props;
 131         int ret, i, max_isel, isink_reg, dcdc_cfg;
 132
 133         /* We need platform data */
 134         if (pdev->dev.parent->platform_data) {
 135                 wm831x_pdata = pdev->dev.parent->platform_data;
 136                 pdata = wm831x_pdata->backlight;
 137         } else {
 138                 pdata = NULL;
 139         }
 140
 141         if (!pdata) {
 142                 dev_err(&pdev->dev, "No platform data supplied\n");
 143                 return -EINVAL;
 144         }
 145
 146         /* Figure out the maximum current we can use */
 147         for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
 148                 if (wm831x_isinkv_values[i] > pdata->max_uA)
 149                         break;
 150         }
 151
 152         if (i == 0) {
 153                 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
 154                 return -EINVAL;
 155         }
 156         max_isel = i - 1;
 157
 158         if (pdata->max_uA != wm831x_isinkv_values[max_isel])
 159                 dev_warn(&pdev->dev,
 160                          "Maximum current is %duA not %duA as requested\n",
 161                          wm831x_isinkv_values[max_isel], pdata->max_uA);
 162
 163         switch (pdata->isink) {
 164         case 1:
 165                 isink_reg = WM831X_CURRENT_SINK_1;
 166                 dcdc_cfg = 0;
 167                 break;
 168         case 2:
 169                 isink_reg = WM831X_CURRENT_SINK_2;
 170                 dcdc_cfg = WM831X_DC4_FBSRC;
 171                 break;
 172         default:
 173                 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
 174                 return -EINVAL;
 175         }
 176
 177         /* Configure the ISINK to use for feedback */
 178         ret = wm831x_reg_unlock(wm831x);
 179         if (ret < 0)
 180                 return ret;
 181
 182         ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
 183                               dcdc_cfg);
 184
 185         wm831x_reg_lock(wm831x);
 186         if (ret < 0)
 187                 return ret;
 188
 189         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 190         if (data == NULL)
 191                 return -ENOMEM;
 192
 193         data->wm831x = wm831x;
 194         data->current_brightness = 0;
 195         data->isink_reg = isink_reg;
 196
 197         memset(&props, 0, sizeof(props));
 198         props.type = BACKLIGHT_RAW;
 199         props.max_brightness = max_isel;
 200         bl = backlight_device_register("wm831x", &pdev->dev, data,
 201                                        &wm831x_backlight_ops, &props);
 202         if (IS_ERR(bl)) {
 203                 dev_err(&pdev->dev, "failed to register backlight\n");
 204                 return PTR_ERR(bl);
 205         }
 206
 207         bl->props.brightness = max_isel;
 208
 209         platform_set_drvdata(pdev, bl);
 210
 211         /* Disable the DCDC if it was started so we can bootstrap */
 212         wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
 213
 214         backlight_update_status(bl);
 215
 216         return 0;
 217 }
 218
 219 static int wm831x_backlight_remove(struct platform_device *pdev)
 220 {
 221         struct backlight_device *bl = platform_get_drvdata(pdev);
 222
 223         backlight_device_unregister(bl);
 224         return 0;
 225 }
 226
 227 static struct platform_driver wm831x_backlight_driver = {
 228         .driver         = {
 229                 .name   = "wm831x-backlight",
 230                 .owner  = THIS_MODULE,
 231         },
 232         .probe          = wm831x_backlight_probe,
 233         .remove         = wm831x_backlight_remove,
 234 };
 235
 236 module_platform_driver(wm831x_backlight_driver);
 237
 238 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
 239 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
 240 MODULE_LICENSE("GPL");
 241 MODULE_ALIAS("platform:wm831x-backlight");