kernel/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
 115         return data->current_brightness;
 116 }
 117
 118 static const struct backlight_ops wm831x_backlight_ops = {
 119         .options = BL_CORE_SUSPENDRESUME,
 120         .update_status  = wm831x_backlight_update_status,
 121         .get_brightness = wm831x_backlight_get_brightness,
 122 };
 123
 124 static int wm831x_backlight_probe(struct platform_device *pdev)
 125 {
 126         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 127         struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
 128         struct wm831x_backlight_pdata *pdata;
 129         struct wm831x_backlight_data *data;
 130         struct backlight_device *bl;
 131         struct backlight_properties props;
 132         int ret, i, max_isel, isink_reg, dcdc_cfg;
 133
 134         /* We need platform data */
 135         if (wm831x_pdata)
 136                 pdata = wm831x_pdata->backlight;
 137         else
 138                 pdata = NULL;
 139
 140         if (!pdata) {
 141                 dev_err(&pdev->dev, "No platform data supplied\n");
 142                 return -EINVAL;
 143         }
 144
 145         /* Figure out the maximum current we can use */
 146         for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
 147                 if (wm831x_isinkv_values[i] > pdata->max_uA)
 148                         break;
 149         }
 150
 151         if (i == 0) {
 152                 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
 153                 return -EINVAL;
 154         }
 155         max_isel = i - 1;
 156
 157         if (pdata->max_uA != wm831x_isinkv_values[max_isel])
 158                 dev_warn(&pdev->dev,
 159                          "Maximum current is %duA not %duA as requested\n",
 160                          wm831x_isinkv_values[max_isel], pdata->max_uA);
 161
 162         switch (pdata->isink) {
 163         case 1:
 164                 isink_reg = WM831X_CURRENT_SINK_1;
 165                 dcdc_cfg = 0;
 166                 break;
 167         case 2:
 168                 isink_reg = WM831X_CURRENT_SINK_2;
 169                 dcdc_cfg = WM831X_DC4_FBSRC;
 170                 break;
 171         default:
 172                 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
 173                 return -EINVAL;
 174         }
 175
 176         /* Configure the ISINK to use for feedback */
 177         ret = wm831x_reg_unlock(wm831x);
 178         if (ret < 0)
 179                 return ret;
 180
 181         ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
 182                               dcdc_cfg);
 183
 184         wm831x_reg_lock(wm831x);
 185         if (ret < 0)
 186                 return ret;
 187
 188         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 189         if (data == NULL)
 190                 return -ENOMEM;
 191
 192         data->wm831x = wm831x;
 193         data->current_brightness = 0;
 194         data->isink_reg = isink_reg;
 195
 196         memset(&props, 0, sizeof(props));
 197         props.type = BACKLIGHT_RAW;
 198         props.max_brightness = max_isel;
 199         bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
 200                                         data, &wm831x_backlight_ops, &props);
 201         if (IS_ERR(bl)) {
 202                 dev_err(&pdev->dev, "failed to register backlight\n");
 203                 return PTR_ERR(bl);
 204         }
 205
 206         bl->props.brightness = max_isel;
 207
 208         platform_set_drvdata(pdev, bl);
 209
 210         /* Disable the DCDC if it was started so we can bootstrap */
 211         wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
 212
 213         backlight_update_status(bl);
 214
 215         return 0;
 216 }
 217
 218 static struct platform_driver wm831x_backlight_driver = {
 219         .driver         = {
 220                 .name   = "wm831x-backlight",
 221         },
 222         .probe          = wm831x_backlight_probe,
 223 };
 224
 225 module_platform_driver(wm831x_backlight_driver);
 226
 227 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
 228 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
 229 MODULE_LICENSE("GPL");
 230 MODULE_ALIAS("platform:wm831x-backlight");