drivers/video/backlight/mt6370-backlight.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2022 Richtek Technology Corp.
   4  *
   5  * Author: ChiaEn Wu <chiaen_wu@richtek.com>
   6  */
   7
   8 #include <linux/backlight.h>
   9 #include <linux/bitfield.h>
  10 #include <linux/bits.h>
  11 #include <linux/gpio/consumer.h>
  12 #include <linux/kernel.h>
  13 #include <linux/minmax.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/module.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/property.h>
  18 #include <linux/regmap.h>
  19
  20 #define MT6370_REG_DEV_INFO             0x100
  21 #define MT6370_REG_BL_EN                0x1A0
  22 #define MT6370_REG_BL_BSTCTRL           0x1A1
  23 #define MT6370_REG_BL_PWM               0x1A2
  24 #define MT6370_REG_BL_DIM2              0x1A4
  25
  26 #define MT6370_VENID_MASK               GENMASK(7, 4)
  27 #define MT6370_BL_EXT_EN_MASK           BIT(7)
  28 #define MT6370_BL_EN_MASK               BIT(6)
  29 #define MT6370_BL_CODE_MASK             BIT(0)
  30 #define MT6370_BL_CH_MASK               GENMASK(5, 2)
  31 #define MT6370_BL_CH_SHIFT              2
  32 #define MT6370_BL_DIM2_COMMON_MASK      GENMASK(2, 0)
  33 #define MT6370_BL_DIM2_COMMON_SHIFT     3
  34 #define MT6370_BL_DIM2_6372_MASK        GENMASK(5, 0)
  35 #define MT6370_BL_DIM2_6372_SHIFT       6
  36 #define MT6370_BL_PWM_EN_MASK           BIT(7)
  37 #define MT6370_BL_PWM_HYS_EN_MASK       BIT(2)
  38 #define MT6370_BL_PWM_HYS_SEL_MASK      GENMASK(1, 0)
  39 #define MT6370_BL_OVP_EN_MASK           BIT(7)
  40 #define MT6370_BL_OVP_SEL_MASK          GENMASK(6, 5)
  41 #define MT6370_BL_OVP_SEL_SHIFT         5
  42 #define MT6370_BL_OC_EN_MASK            BIT(3)
  43 #define MT6370_BL_OC_SEL_MASK           GENMASK(2, 1)
  44 #define MT6370_BL_OC_SEL_SHIFT          1
  45
  46 #define MT6370_BL_PWM_HYS_TH_MIN_STEP   1
  47 #define MT6370_BL_PWM_HYS_TH_MAX_STEP   64
  48 #define MT6370_BL_OVP_MIN_UV            17000000
  49 #define MT6370_BL_OVP_MAX_UV            29000000
  50 #define MT6370_BL_OVP_STEP_UV           4000000
  51 #define MT6370_BL_OCP_MIN_UA            900000
  52 #define MT6370_BL_OCP_MAX_UA            1800000
  53 #define MT6370_BL_OCP_STEP_UA           300000
  54 #define MT6370_BL_MAX_COMMON_BRIGHTNESS 2048
  55 #define MT6370_BL_MAX_6372_BRIGHTNESS   16384
  56 #define MT6370_BL_MAX_CH                15
  57
  58 enum {
  59         MT6370_VID_COMMON = 1,
  60         MT6370_VID_6372,
  61 };
  62
  63 struct mt6370_priv {
  64         u8 dim2_mask;
  65         u8 dim2_shift;
  66         int def_max_brightness;
  67         struct backlight_device *bl;
  68         struct device *dev;
  69         struct gpio_desc *enable_gpio;
  70         struct regmap *regmap;
  71 };
  72
  73 static int mt6370_bl_update_status(struct backlight_device *bl_dev)
  74 {
  75         struct mt6370_priv *priv = bl_get_data(bl_dev);
  76         int brightness = backlight_get_brightness(bl_dev);
  77         unsigned int enable_val;
  78         u8 brightness_val[2];
  79         int ret;
  80
  81         if (brightness) {
  82                 brightness_val[0] = (brightness - 1) & priv->dim2_mask;
  83                 brightness_val[1] = (brightness - 1) >> priv->dim2_shift;
  84
  85                 ret = regmap_raw_write(priv->regmap, MT6370_REG_BL_DIM2,
  86                                        brightness_val, sizeof(brightness_val));
  87                 if (ret)
  88                         return ret;
  89         }
  90
  91         gpiod_set_value(priv->enable_gpio, !!brightness);
  92
  93         enable_val = brightness ? MT6370_BL_EN_MASK : 0;
  94         return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN,
  95                                   MT6370_BL_EN_MASK, enable_val);
  96 }
  97
  98 static int mt6370_bl_get_brightness(struct backlight_device *bl_dev)
  99 {
 100         struct mt6370_priv *priv = bl_get_data(bl_dev);
 101         unsigned int enable;
 102         u8 brightness_val[2];
 103         int brightness, ret;
 104
 105         ret = regmap_read(priv->regmap, MT6370_REG_BL_EN, &enable);
 106         if (ret)
 107                 return ret;
 108
 109         if (!(enable & MT6370_BL_EN_MASK))
 110                 return 0;
 111
 112         ret = regmap_raw_read(priv->regmap, MT6370_REG_BL_DIM2,
 113                               brightness_val, sizeof(brightness_val));
 114         if (ret)
 115                 return ret;
 116
 117         brightness = brightness_val[1] << priv->dim2_shift;
 118         brightness += brightness_val[0] & priv->dim2_mask;
 119
 120         return brightness + 1;
 121 }
 122
 123 static const struct backlight_ops mt6370_bl_ops = {
 124         .options = BL_CORE_SUSPENDRESUME,
 125         .update_status = mt6370_bl_update_status,
 126         .get_brightness = mt6370_bl_get_brightness,
 127 };
 128
 129 static int mt6370_init_backlight_properties(struct mt6370_priv *priv,
 130                                             struct backlight_properties *props)
 131 {
 132         struct device *dev = priv->dev;
 133         u8 prop_val;
 134         u32 brightness, ovp_uV, ocp_uA;
 135         unsigned int mask, val;
 136         int ret;
 137
 138         /* Vendor optional properties */
 139         val = 0;
 140         if (device_property_read_bool(dev, "mediatek,bled-pwm-enable"))
 141                 val |= MT6370_BL_PWM_EN_MASK;
 142
 143         if (device_property_read_bool(dev, "mediatek,bled-pwm-hys-enable"))
 144                 val |= MT6370_BL_PWM_HYS_EN_MASK;
 145
 146         ret = device_property_read_u8(dev,
 147                                       "mediatek,bled-pwm-hys-input-th-steps",
 148                                       &prop_val);
 149         if (!ret) {
 150                 prop_val = clamp_val(prop_val,
 151                                      MT6370_BL_PWM_HYS_TH_MIN_STEP,
 152                                      MT6370_BL_PWM_HYS_TH_MAX_STEP);
 153                 prop_val = prop_val <= 1 ? 0 :
 154                            prop_val <= 4 ? 1 :
 155                            prop_val <= 16 ? 2 : 3;
 156                 val |= prop_val;
 157         }
 158
 159         ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
 160                                  val, val);
 161         if (ret)
 162                 return ret;
 163
 164         val = 0;
 165         if (device_property_read_bool(dev, "mediatek,bled-ovp-shutdown"))
 166                 val |= MT6370_BL_OVP_EN_MASK;
 167
 168         ret = device_property_read_u32(dev, "mediatek,bled-ovp-microvolt",
 169                                        &ovp_uV);
 170         if (!ret) {
 171                 ovp_uV = clamp_val(ovp_uV, MT6370_BL_OVP_MIN_UV,
 172                                    MT6370_BL_OVP_MAX_UV);
 173                 ovp_uV = DIV_ROUND_UP(ovp_uV - MT6370_BL_OVP_MIN_UV,
 174                                       MT6370_BL_OVP_STEP_UV);
 175                 val |= ovp_uV << MT6370_BL_OVP_SEL_SHIFT;
 176         }
 177
 178         if (device_property_read_bool(dev, "mediatek,bled-ocp-shutdown"))
 179                 val |= MT6370_BL_OC_EN_MASK;
 180
 181         ret = device_property_read_u32(dev, "mediatek,bled-ocp-microamp",
 182                                        &ocp_uA);
 183         if (!ret) {
 184                 ocp_uA = clamp_val(ocp_uA, MT6370_BL_OCP_MIN_UA,
 185                                    MT6370_BL_OCP_MAX_UA);
 186                 ocp_uA = DIV_ROUND_UP(ocp_uA - MT6370_BL_OCP_MIN_UA,
 187                                       MT6370_BL_OCP_STEP_UA);
 188                 val |= ocp_uA << MT6370_BL_OC_SEL_SHIFT;
 189         }
 190
 191         ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
 192                                  val, val);
 193         if (ret)
 194                 return ret;
 195
 196         /* Common properties */
 197         ret = device_property_read_u32(dev, "max-brightness", &brightness);
 198         if (ret)
 199                 brightness = priv->def_max_brightness;
 200
 201         props->max_brightness = min_t(u32, brightness, priv->def_max_brightness);
 202
 203         ret = device_property_read_u32(dev, "default-brightness", &brightness);
 204         if (ret)
 205                 brightness = props->max_brightness;
 206
 207         props->brightness = min_t(u32, brightness, props->max_brightness);
 208
 209         val = 0;
 210         if (device_property_read_bool(dev, "mediatek,bled-exponential-mode-enable")) {
 211                 val |= MT6370_BL_CODE_MASK;
 212                 props->scale = BACKLIGHT_SCALE_NON_LINEAR;
 213         } else
 214                 props->scale = BACKLIGHT_SCALE_LINEAR;
 215
 216         ret = device_property_read_u8(dev, "mediatek,bled-channel-use",
 217                                       &prop_val);
 218         if (ret) {
 219                 dev_err(dev, "mediatek,bled-channel-use DT property missing\n");
 220                 return ret;
 221         }
 222
 223         if (!prop_val || prop_val > MT6370_BL_MAX_CH) {
 224                 dev_err(dev,
 225                         "No channel specified or over than upper bound (%d)\n",
 226                         prop_val);
 227                 return -EINVAL;
 228         }
 229
 230         mask = MT6370_BL_EXT_EN_MASK | MT6370_BL_CH_MASK;
 231         val |= prop_val << MT6370_BL_CH_SHIFT;
 232
 233         if (priv->enable_gpio)
 234                 val |= MT6370_BL_EXT_EN_MASK;
 235
 236         return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN, mask, val);
 237 }
 238
 239 static int mt6370_check_vendor_info(struct mt6370_priv *priv)
 240 {
 241         /*
 242          * Because MT6372 uses 14 bits to control the brightness,
 243          * MT6370 and MT6371 use 11 bits. This function is used
 244          * to check the vendor's ID and set the relative hardware
 245          * mask, shift and default maximum brightness value that
 246          * should be used.
 247          */
 248         unsigned int dev_info, hw_vid, of_vid;
 249         int ret;
 250
 251         ret = regmap_read(priv->regmap, MT6370_REG_DEV_INFO, &dev_info);
 252         if (ret)
 253                 return ret;
 254
 255         of_vid = (uintptr_t)device_get_match_data(priv->dev);
 256         hw_vid = FIELD_GET(MT6370_VENID_MASK, dev_info);
 257         hw_vid = (hw_vid == 0x9 || hw_vid == 0xb) ? MT6370_VID_6372 : MT6370_VID_COMMON;
 258         if (hw_vid != of_vid)
 259                 return dev_err_probe(priv->dev, -EINVAL,
 260                                      "Buggy DT, wrong compatible string\n");
 261
 262         if (hw_vid == MT6370_VID_6372) {
 263                 priv->dim2_mask = MT6370_BL_DIM2_6372_MASK;
 264                 priv->dim2_shift = MT6370_BL_DIM2_6372_SHIFT;
 265                 priv->def_max_brightness = MT6370_BL_MAX_6372_BRIGHTNESS;
 266         } else {
 267                 priv->dim2_mask = MT6370_BL_DIM2_COMMON_MASK;
 268                 priv->dim2_shift = MT6370_BL_DIM2_COMMON_SHIFT;
 269                 priv->def_max_brightness = MT6370_BL_MAX_COMMON_BRIGHTNESS;
 270         }
 271
 272         return 0;
 273 }
 274
 275 static int mt6370_bl_probe(struct platform_device *pdev)
 276 {
 277         struct backlight_properties props = {
 278                 .type = BACKLIGHT_RAW,
 279         };
 280         struct device *dev = &pdev->dev;
 281         struct mt6370_priv *priv;
 282         int ret;
 283
 284         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 285         if (!priv)
 286                 return -ENOMEM;
 287
 288         priv->dev = dev;
 289
 290         priv->regmap = dev_get_regmap(dev->parent, NULL);
 291         if (!priv->regmap)
 292                 return dev_err_probe(dev, -ENODEV, "Failed to get regmap\n");
 293
 294         ret = mt6370_check_vendor_info(priv);
 295         if (ret)
 296                 return dev_err_probe(dev, ret, "Failed to check vendor info\n");
 297
 298         priv->enable_gpio = devm_gpiod_get_optional(dev, "enable",
 299                                                     GPIOD_OUT_HIGH);
 300         if (IS_ERR(priv->enable_gpio))
 301                 return dev_err_probe(dev, PTR_ERR(priv->enable_gpio),
 302                                      "Failed to get 'enable' gpio\n");
 303
 304         ret = mt6370_init_backlight_properties(priv, &props);
 305         if (ret)
 306                 return dev_err_probe(dev, ret,
 307                                      "Failed to init backlight properties\n");
 308
 309         priv->bl = devm_backlight_device_register(dev, pdev->name, dev, priv,
 310                                                   &mt6370_bl_ops, &props);
 311         if (IS_ERR(priv->bl))
 312                 return dev_err_probe(dev, PTR_ERR(priv->bl),
 313                                      "Failed to register backlight\n");
 314
 315         backlight_update_status(priv->bl);
 316         platform_set_drvdata(pdev, priv);
 317
 318         return 0;
 319 }
 320
 321 static int mt6370_bl_remove(struct platform_device *pdev)
 322 {
 323         struct mt6370_priv *priv = platform_get_drvdata(pdev);
 324         struct backlight_device *bl_dev = priv->bl;
 325
 326         bl_dev->props.brightness = 0;
 327         backlight_update_status(priv->bl);
 328
 329         return 0;
 330 }
 331
 332 static const struct of_device_id mt6370_bl_of_match[] = {
 333         { .compatible = "mediatek,mt6370-backlight", .data = (void *)MT6370_VID_COMMON },
 334         { .compatible = "mediatek,mt6372-backlight", .data = (void *)MT6370_VID_6372 },
 335         {}
 336 };
 337 MODULE_DEVICE_TABLE(of, mt6370_bl_of_match);
 338
 339 static struct platform_driver mt6370_bl_driver = {
 340         .driver = {
 341                 .name = "mt6370-backlight",
 342                 .of_match_table = mt6370_bl_of_match,
 343         },
 344         .probe = mt6370_bl_probe,
 345         .remove = mt6370_bl_remove,
 346 };
 347 module_platform_driver(mt6370_bl_driver);
 348
 349 MODULE_AUTHOR("ChiaEn Wu <chiaen_wu@richtek.com>");
 350 MODULE_DESCRIPTION("MediaTek MT6370 Backlight Driver");
 351 MODULE_LICENSE("GPL v2");