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         return wm831x_backlight_set(bl, backlight_get_brightness(bl));
  95 }
  96
  97 static int wm831x_backlight_get_brightness(struct backlight_device *bl)
  98 {
  99         struct wm831x_backlight_data *data = bl_get_data(bl);
 100
 101         return data->current_brightness;
 102 }
 103
 104 static const struct backlight_ops wm831x_backlight_ops = {
 105         .options = BL_CORE_SUSPENDRESUME,
 106         .update_status  = wm831x_backlight_update_status,
 107         .get_brightness = wm831x_backlight_get_brightness,
 108 };
 109
 110 static int wm831x_backlight_probe(struct platform_device *pdev)
 111 {
 112         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 113         struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
 114         struct wm831x_backlight_pdata *pdata;
 115         struct wm831x_backlight_data *data;
 116         struct backlight_device *bl;
 117         struct backlight_properties props;
 118         int ret, i, max_isel, isink_reg, dcdc_cfg;
 119
 120         /* We need platform data */
 121         if (wm831x_pdata)
 122                 pdata = wm831x_pdata->backlight;
 123         else
 124                 pdata = NULL;
 125
 126         if (!pdata) {
 127                 dev_err(&pdev->dev, "No platform data supplied\n");
 128                 return -EINVAL;
 129         }
 130
 131         /* Figure out the maximum current we can use */
 132         for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
 133                 if (wm831x_isinkv_values[i] > pdata->max_uA)
 134                         break;
 135         }
 136
 137         if (i == 0) {
 138                 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
 139                 return -EINVAL;
 140         }
 141         max_isel = i - 1;
 142
 143         if (pdata->max_uA != wm831x_isinkv_values[max_isel])
 144                 dev_warn(&pdev->dev,
 145                          "Maximum current is %duA not %duA as requested\n",
 146                          wm831x_isinkv_values[max_isel], pdata->max_uA);
 147
 148         switch (pdata->isink) {
 149         case 1:
 150                 isink_reg = WM831X_CURRENT_SINK_1;
 151                 dcdc_cfg = 0;
 152                 break;
 153         case 2:
 154                 isink_reg = WM831X_CURRENT_SINK_2;
 155                 dcdc_cfg = WM831X_DC4_FBSRC;
 156                 break;
 157         default:
 158                 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
 159                 return -EINVAL;
 160         }
 161
 162         /* Configure the ISINK to use for feedback */
 163         ret = wm831x_reg_unlock(wm831x);
 164         if (ret < 0)
 165                 return ret;
 166
 167         ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
 168                               dcdc_cfg);
 169
 170         wm831x_reg_lock(wm831x);
 171         if (ret < 0)
 172                 return ret;
 173
 174         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 175         if (data == NULL)
 176                 return -ENOMEM;
 177
 178         data->wm831x = wm831x;
 179         data->current_brightness = 0;
 180         data->isink_reg = isink_reg;
 181
 182         memset(&props, 0, sizeof(props));
 183         props.type = BACKLIGHT_RAW;
 184         props.max_brightness = max_isel;
 185         bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
 186                                         data, &wm831x_backlight_ops, &props);
 187         if (IS_ERR(bl)) {
 188                 dev_err(&pdev->dev, "failed to register backlight\n");
 189                 return PTR_ERR(bl);
 190         }
 191
 192         bl->props.brightness = max_isel;
 193
 194         platform_set_drvdata(pdev, bl);
 195
 196         /* Disable the DCDC if it was started so we can bootstrap */
 197         wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
 198
 199         backlight_update_status(bl);
 200
 201         return 0;
 202 }
 203
 204 static struct platform_driver wm831x_backlight_driver = {
 205         .driver         = {
 206                 .name   = "wm831x-backlight",
 207         },
 208         .probe          = wm831x_backlight_probe,
 209 };
 210
 211 module_platform_driver(wm831x_backlight_driver);
 212
 213 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
 214 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
 215 MODULE_LICENSE("GPL");
 216 MODULE_ALIAS("platform:wm831x-backlight");