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/fb.h>
  15 #include <linux/backlight.h>
  16
  17 #include <linux/mfd/wm831x/core.h>
  18 #include <linux/mfd/wm831x/pdata.h>
  19 #include <linux/mfd/wm831x/regulator.h>
  20
  21 struct wm831x_backlight_data {
  22         struct wm831x *wm831x;
  23         int isink_reg;
  24         int current_brightness;
  25 };
  26
  27 static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
  28 {
  29         struct wm831x_backlight_data *data = bl_get_data(bl);
  30         struct wm831x *wm831x = data->wm831x;
  31         int power_up = !data->current_brightness && brightness;
  32         int power_down = data->current_brightness && !brightness;
  33         int ret;
  34
  35         if (power_up) {
  36                 /* Enable the ISINK */
  37                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  38                                       WM831X_CS1_ENA, WM831X_CS1_ENA);
  39                 if (ret < 0)
  40                         goto err;
  41
  42                 /* Enable the DC-DC */
  43                 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
  44                                       WM831X_DC4_ENA, WM831X_DC4_ENA);
  45                 if (ret < 0)
  46                         goto err;
  47         }
  48
  49         if (power_down) {
  50                 /* DCDC first */
  51                 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
  52                                       WM831X_DC4_ENA, 0);
  53                 if (ret < 0)
  54                         goto err;
  55
  56                 /* ISINK */
  57                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  58                                       WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
  59                 if (ret < 0)
  60                         goto err;
  61         }
  62
  63         /* Set the new brightness */
  64         ret = wm831x_set_bits(wm831x, data->isink_reg,
  65                               WM831X_CS1_ISEL_MASK, brightness);
  66         if (ret < 0)
  67                 goto err;
  68
  69         if (power_up) {
  70                 /* Drive current through the ISINK */
  71                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  72                                       WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
  73                 if (ret < 0)
  74                         return ret;
  75         }
  76
  77         data->current_brightness = brightness;
  78
  79         return 0;
  80
  81 err:
  82         /* If we were in the middle of a power transition always shut down
  83          * for safety.
  84          */
  85         if (power_up || power_down) {
  86                 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
  87                 wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
  88         }
  89
  90         return ret;
  91 }
  92
  93 static int wm831x_backlight_update_status(struct backlight_device *bl)
  94 {
  95         int brightness = bl->props.brightness;
  96
  97         if (bl->props.power != FB_BLANK_UNBLANK)
  98                 brightness = 0;
  99
 100         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
 101                 brightness = 0;
 102
 103         if (bl->props.state & BL_CORE_SUSPENDED)
 104                 brightness = 0;
 105
 106         return wm831x_backlight_set(bl, brightness);
 107 }
 108
 109 static int wm831x_backlight_get_brightness(struct backlight_device *bl)
 110 {
 111         struct wm831x_backlight_data *data = bl_get_data(bl);
 112         return data->current_brightness;
 113 }
 114
 115 static const struct backlight_ops wm831x_backlight_ops = {
 116         .options = BL_CORE_SUSPENDRESUME,
 117         .update_status  = wm831x_backlight_update_status,
 118         .get_brightness = wm831x_backlight_get_brightness,
 119 };
 120
 121 static int wm831x_backlight_probe(struct platform_device *pdev)
 122 {
 123         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 124         struct wm831x_pdata *wm831x_pdata;
 125         struct wm831x_backlight_pdata *pdata;
 126         struct wm831x_backlight_data *data;
 127         struct backlight_device *bl;
 128         struct backlight_properties props;
 129         int ret, i, max_isel, isink_reg, dcdc_cfg;
 130
 131         /* We need platform data */
 132         if (pdev->dev.parent->platform_data) {
 133                 wm831x_pdata = pdev->dev.parent->platform_data;
 134                 pdata = wm831x_pdata->backlight;
 135         } else {
 136                 pdata = NULL;
 137         }
 138
 139         if (!pdata) {
 140                 dev_err(&pdev->dev, "No platform data supplied\n");
 141                 return -EINVAL;
 142         }
 143
 144         /* Figure out the maximum current we can use */
 145         for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
 146                 if (wm831x_isinkv_values[i] > pdata->max_uA)
 147                         break;
 148         }
 149
 150         if (i == 0) {
 151                 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
 152                 return -EINVAL;
 153         }
 154         max_isel = i - 1;
 155
 156         if (pdata->max_uA != wm831x_isinkv_values[max_isel])
 157                 dev_warn(&pdev->dev,
 158                          "Maximum current is %duA not %duA as requested\n",
 159                          wm831x_isinkv_values[max_isel], pdata->max_uA);
 160
 161         switch (pdata->isink) {
 162         case 1:
 163                 isink_reg = WM831X_CURRENT_SINK_1;
 164                 dcdc_cfg = 0;
 165                 break;
 166         case 2:
 167                 isink_reg = WM831X_CURRENT_SINK_2;
 168                 dcdc_cfg = WM831X_DC4_FBSRC;
 169                 break;
 170         default:
 171                 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
 172                 return -EINVAL;
 173         }
 174
 175         /* Configure the ISINK to use for feedback */
 176         ret = wm831x_reg_unlock(wm831x);
 177         if (ret < 0)
 178                 return ret;
 179
 180         ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
 181                               dcdc_cfg);
 182
 183         wm831x_reg_lock(wm831x);
 184         if (ret < 0)
 185                 return ret;
 186
 187         data = kzalloc(sizeof(*data), GFP_KERNEL);
 188         if (data == NULL)
 189                 return -ENOMEM;
 190
 191         data->wm831x = wm831x;
 192         data->current_brightness = 0;
 193         data->isink_reg = isink_reg;
 194
 195         props.max_brightness = max_isel;
 196         bl = backlight_device_register("wm831x", &pdev->dev, data,
 197                                        &wm831x_backlight_ops, &props);
 198         if (IS_ERR(bl)) {
 199                 dev_err(&pdev->dev, "failed to register backlight\n");
 200                 kfree(data);
 201                 return PTR_ERR(bl);
 202         }
 203
 204         bl->props.brightness = max_isel;
 205
 206         platform_set_drvdata(pdev, bl);
 207
 208         /* Disable the DCDC if it was started so we can bootstrap */
 209         wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
 210
 211
 212         backlight_update_status(bl);
 213
 214         return 0;
 215 }
 216
 217 static int wm831x_backlight_remove(struct platform_device *pdev)
 218 {
 219         struct backlight_device *bl = platform_get_drvdata(pdev);
 220         struct wm831x_backlight_data *data = bl_get_data(bl);
 221
 222         backlight_device_unregister(bl);
 223         kfree(data);
 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 static int __init wm831x_backlight_init(void)
 237 {
 238         return platform_driver_register(&wm831x_backlight_driver);
 239 }
 240 module_init(wm831x_backlight_init);
 241
 242 static void __exit wm831x_backlight_exit(void)
 243 {
 244         platform_driver_unregister(&wm831x_backlight_driver);
 245 }
 246 module_exit(wm831x_backlight_exit);
 247
 248 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
 249 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
 250 MODULE_LICENSE("GPL");
 251 MODULE_ALIAS("platform:wm831x-backlight");