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 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         int ret, i, max_isel, isink_reg, dcdc_cfg;
 129
 130         /* We need platform data */
 131         if (pdev->dev.parent->platform_data) {
 132                 wm831x_pdata = pdev->dev.parent->platform_data;
 133                 pdata = wm831x_pdata->backlight;
 134         } else {
 135                 pdata = NULL;
 136         }
 137
 138         if (!pdata) {
 139                 dev_err(&pdev->dev, "No platform data supplied\n");
 140                 return -EINVAL;
 141         }
 142
 143         /* Figure out the maximum current we can use */
 144         for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
 145                 if (wm831x_isinkv_values[i] > pdata->max_uA)
 146                         break;
 147         }
 148
 149         if (i == 0) {
 150                 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
 151                 return -EINVAL;
 152         }
 153         max_isel = i - 1;
 154
 155         if (pdata->max_uA != wm831x_isinkv_values[max_isel])
 156                 dev_warn(&pdev->dev,
 157                          "Maximum current is %duA not %duA as requested\n",
 158                          wm831x_isinkv_values[max_isel], pdata->max_uA);
 159
 160         switch (pdata->isink) {
 161         case 1:
 162                 isink_reg = WM831X_CURRENT_SINK_1;
 163                 dcdc_cfg = 0;
 164                 break;
 165         case 2:
 166                 isink_reg = WM831X_CURRENT_SINK_2;
 167                 dcdc_cfg = WM831X_DC4_FBSRC;
 168                 break;
 169         default:
 170                 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
 171                 return -EINVAL;
 172         }
 173
 174         /* Configure the ISINK to use for feedback */
 175         ret = wm831x_reg_unlock(wm831x);
 176         if (ret < 0)
 177                 return ret;
 178
 179         ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
 180                               dcdc_cfg);
 181
 182         wm831x_reg_lock(wm831x);
 183         if (ret < 0)
 184                 return ret;
 185
 186         data = kzalloc(sizeof(*data), GFP_KERNEL);
 187         if (data == NULL)
 188                 return -ENOMEM;
 189
 190         data->wm831x = wm831x;
 191         data->current_brightness = 0;
 192         data->isink_reg = isink_reg;
 193
 194         bl = backlight_device_register("wm831x", &pdev->dev,
 195                         data, &wm831x_backlight_ops);
 196         if (IS_ERR(bl)) {
 197                 dev_err(&pdev->dev, "failed to register backlight\n");
 198                 kfree(data);
 199                 return PTR_ERR(bl);
 200         }
 201
 202         bl->props.max_brightness = max_isel;
 203         bl->props.brightness = max_isel;
 204
 205         platform_set_drvdata(pdev, bl);
 206
 207         /* Disable the DCDC if it was started so we can bootstrap */
 208         wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
 209
 210
 211         backlight_update_status(bl);
 212
 213         return 0;
 214 }
 215
 216 static int wm831x_backlight_remove(struct platform_device *pdev)
 217 {
 218         struct backlight_device *bl = platform_get_drvdata(pdev);
 219         struct wm831x_backlight_data *data = bl_get_data(bl);
 220
 221         backlight_device_unregister(bl);
 222         kfree(data);
 223         return 0;
 224 }
 225
 226 static struct platform_driver wm831x_backlight_driver = {
 227         .driver         = {
 228                 .name   = "wm831x-backlight",
 229                 .owner  = THIS_MODULE,
 230         },
 231         .probe          = wm831x_backlight_probe,
 232         .remove         = wm831x_backlight_remove,
 233 };
 234
 235 static int __init wm831x_backlight_init(void)
 236 {
 237         return platform_driver_register(&wm831x_backlight_driver);
 238 }
 239 module_init(wm831x_backlight_init);
 240
 241 static void __exit wm831x_backlight_exit(void)
 242 {
 243         platform_driver_unregister(&wm831x_backlight_driver);
 244 }
 245 module_exit(wm831x_backlight_exit);
 246
 247 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
 248 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
 249 MODULE_LICENSE("GPL");
 250 MODULE_ALIAS("platform:wm831x-backlight");