drivers/video/backlight/wm831x_bl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Backlight driver for Wolfson Microelectronics WM831x PMICs
   4  *
   5  * Copyright 2009 Wolfson Microelectonics plc
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/module.h>
  12 #include <linux/fb.h>
  13 #include <linux/backlight.h>
  14 #include <linux/slab.h>
  15
  16 #include <linux/mfd/wm831x/core.h>
  17 #include <linux/mfd/wm831x/pdata.h>
  18 #include <linux/mfd/wm831x/regulator.h>
  19
  20 struct wm831x_backlight_data {
  21         struct wm831x *wm831x;
  22         int isink_reg;
  23         int current_brightness;
  24 };
  25
  26 static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
  27 {
  28         struct wm831x_backlight_data *data = bl_get_data(bl);
  29         struct wm831x *wm831x = data->wm831x;
  30         int power_up = !data->current_brightness && brightness;
  31         int power_down = data->current_brightness && !brightness;
  32         int ret;
  33
  34         if (power_up) {
  35                 /* Enable the ISINK */
  36                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  37                                       WM831X_CS1_ENA, WM831X_CS1_ENA);
  38                 if (ret < 0)
  39                         goto err;
  40
  41                 /* Enable the DC-DC */
  42                 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
  43                                       WM831X_DC4_ENA, WM831X_DC4_ENA);
  44                 if (ret < 0)
  45                         goto err;
  46         }
  47
  48         if (power_down) {
  49                 /* DCDC first */
  50                 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
  51                                       WM831X_DC4_ENA, 0);
  52                 if (ret < 0)
  53                         goto err;
  54
  55                 /* ISINK */
  56                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  57                                       WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
  58                 if (ret < 0)
  59                         goto err;
  60         }
  61
  62         /* Set the new brightness */
  63         ret = wm831x_set_bits(wm831x, data->isink_reg,
  64                               WM831X_CS1_ISEL_MASK, brightness);
  65         if (ret < 0)
  66                 goto err;
  67
  68         if (power_up) {
  69                 /* Drive current through the ISINK */
  70                 ret = wm831x_set_bits(wm831x, data->isink_reg,
  71                                       WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
  72                 if (ret < 0)
  73                         return ret;
  74         }
  75
  76         data->current_brightness = brightness;
  77
  78         return 0;
  79
  80 err:
  81         /* If we were in the middle of a power transition always shut down
  82          * for safety.
  83          */
  84         if (power_up || power_down) {
  85                 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
  86                 wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
  87         }
  88
  89         return ret;
  90 }
  91
  92 static int wm831x_backlight_update_status(struct backlight_device *bl)
  93 {
  94         int brightness = bl->props.brightness;
  95
  96         if (bl->props.power != FB_BLANK_UNBLANK)
  97                 brightness = 0;
  98
  99         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
 100                 brightness = 0;
 101
 102         if (bl->props.state & BL_CORE_SUSPENDED)
 103                 brightness = 0;
 104
 105         return wm831x_backlight_set(bl, brightness);
 106 }
 107
 108 static int wm831x_backlight_get_brightness(struct backlight_device *bl)
 109 {
 110         struct wm831x_backlight_data *data = bl_get_data(bl);
 111
 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 = dev_get_platdata(pdev->dev.parent);
 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 (wm831x_pdata)
 133                 pdata = wm831x_pdata->backlight;
 134         else
 135                 pdata = NULL;
 136
 137         if (!pdata) {
 138                 dev_err(&pdev->dev, "No platform data supplied\n");
 139                 return -EINVAL;
 140         }
 141
 142         /* Figure out the maximum current we can use */
 143         for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
 144                 if (wm831x_isinkv_values[i] > pdata->max_uA)
 145                         break;
 146         }
 147
 148         if (i == 0) {
 149                 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
 150                 return -EINVAL;
 151         }
 152         max_isel = i - 1;
 153
 154         if (pdata->max_uA != wm831x_isinkv_values[max_isel])
 155                 dev_warn(&pdev->dev,
 156                          "Maximum current is %duA not %duA as requested\n",
 157                          wm831x_isinkv_values[max_isel], pdata->max_uA);
 158
 159         switch (pdata->isink) {
 160         case 1:
 161                 isink_reg = WM831X_CURRENT_SINK_1;
 162                 dcdc_cfg = 0;
 163                 break;
 164         case 2:
 165                 isink_reg = WM831X_CURRENT_SINK_2;
 166                 dcdc_cfg = WM831X_DC4_FBSRC;
 167                 break;
 168         default:
 169                 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
 170                 return -EINVAL;
 171         }
 172
 173         /* Configure the ISINK to use for feedback */
 174         ret = wm831x_reg_unlock(wm831x);
 175         if (ret < 0)
 176                 return ret;
 177
 178         ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
 179                               dcdc_cfg);
 180
 181         wm831x_reg_lock(wm831x);
 182         if (ret < 0)
 183                 return ret;
 184
 185         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 186         if (data == NULL)
 187                 return -ENOMEM;
 188
 189         data->wm831x = wm831x;
 190         data->current_brightness = 0;
 191         data->isink_reg = isink_reg;
 192
 193         memset(&props, 0, sizeof(props));
 194         props.type = BACKLIGHT_RAW;
 195         props.max_brightness = max_isel;
 196         bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
 197                                         data, &wm831x_backlight_ops, &props);
 198         if (IS_ERR(bl)) {
 199                 dev_err(&pdev->dev, "failed to register backlight\n");
 200                 return PTR_ERR(bl);
 201         }
 202
 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         backlight_update_status(bl);
 211
 212         return 0;
 213 }
 214
 215 static struct platform_driver wm831x_backlight_driver = {
 216         .driver         = {
 217                 .name   = "wm831x-backlight",
 218         },
 219         .probe          = wm831x_backlight_probe,
 220 };
 221
 222 module_platform_driver(wm831x_backlight_driver);
 223
 224 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
 225 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
 226 MODULE_LICENSE("GPL");
 227 MODULE_ALIAS("platform:wm831x-backlight");