drivers/mfd/rt4831.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (c) 2021 Richtek Technology Corp.
   4  *
   5  * Author: ChiYuan Huang <cy_huang@richtek.com>
   6  */
   7
   8 #include <linux/gpio/consumer.h>
   9 #include <linux/i2c.h>
  10 #include <linux/kernel.h>
  11 #include <linux/mfd/core.h>
  12 #include <linux/module.h>
  13 #include <linux/regmap.h>
  14
  15 #define RT4831_REG_REVISION     0x01
  16 #define RT4831_REG_ENABLE       0x08
  17 #define RT4831_REG_I2CPROT      0x15
  18
  19 #define RICHTEK_VENDOR_ID       0x03
  20 #define RT4831_VID_MASK         GENMASK(1, 0)
  21 #define RT4831_RESET_MASK       BIT(7)
  22 #define RT4831_I2CSAFETMR_MASK  BIT(0)
  23
  24 static const struct mfd_cell rt4831_subdevs[] = {
  25         MFD_CELL_OF("rt4831-backlight", NULL, NULL, 0, 0, "richtek,rt4831-backlight"),
  26         MFD_CELL_NAME("rt4831-regulator")
  27 };
  28
  29 static bool rt4831_is_accessible_reg(struct device *dev, unsigned int reg)
  30 {
  31         if (reg >= RT4831_REG_REVISION && reg <= RT4831_REG_I2CPROT)
  32                 return true;
  33         return false;
  34 }
  35
  36 static const struct regmap_config rt4831_regmap_config = {
  37         .reg_bits = 8,
  38         .val_bits = 8,
  39         .max_register = RT4831_REG_I2CPROT,
  40
  41         .readable_reg = rt4831_is_accessible_reg,
  42         .writeable_reg = rt4831_is_accessible_reg,
  43 };
  44
  45 static int rt4831_probe(struct i2c_client *client)
  46 {
  47         struct gpio_desc *enable_gpio;
  48         struct regmap *regmap;
  49         unsigned int chip_id;
  50         int ret;
  51
  52         enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
  53         if (IS_ERR(enable_gpio)) {
  54                 dev_err(&client->dev, "Failed to get 'enable' GPIO\n");
  55                 return PTR_ERR(enable_gpio);
  56         }
  57
  58         regmap = devm_regmap_init_i2c(client, &rt4831_regmap_config);
  59         if (IS_ERR(regmap)) {
  60                 dev_err(&client->dev, "Failed to initialize regmap\n");
  61                 return PTR_ERR(regmap);
  62         }
  63
  64         ret = regmap_read(regmap, RT4831_REG_REVISION, &chip_id);
  65         if (ret) {
  66                 dev_err(&client->dev, "Failed to get H/W revision\n");
  67                 return ret;
  68         }
  69
  70         if ((chip_id & RT4831_VID_MASK) != RICHTEK_VENDOR_ID) {
  71                 dev_err(&client->dev, "Chip vendor ID 0x%02x not matched\n", chip_id);
  72                 return -ENODEV;
  73         }
  74
  75         /*
  76          * Used to prevent the abnormal shutdown.
  77          * If SCL/SDA both keep low for one second to reset HW.
  78          */
  79         ret = regmap_update_bits(regmap, RT4831_REG_I2CPROT, RT4831_I2CSAFETMR_MASK,
  80                                  RT4831_I2CSAFETMR_MASK);
  81         if (ret) {
  82                 dev_err(&client->dev, "Failed to enable I2C safety timer\n");
  83                 return ret;
  84         }
  85
  86         return devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO, rt4831_subdevs,
  87                                     ARRAY_SIZE(rt4831_subdevs), NULL, 0, NULL);
  88 }
  89
  90 static void rt4831_remove(struct i2c_client *client)
  91 {
  92         struct regmap *regmap = dev_get_regmap(&client->dev, NULL);
  93         int ret;
  94
  95         /* Disable WLED and DSV outputs */
  96         ret = regmap_update_bits(regmap, RT4831_REG_ENABLE, RT4831_RESET_MASK, RT4831_RESET_MASK);
  97         if (ret)
  98                 dev_warn(&client->dev, "Failed to disable outputs (%pe)\n", ERR_PTR(ret));
  99 }
 100
 101 static const struct of_device_id __maybe_unused rt4831_of_match[] = {
 102         { .compatible = "richtek,rt4831", },
 103         {}
 104 };
 105 MODULE_DEVICE_TABLE(of, rt4831_of_match);
 106
 107 static struct i2c_driver rt4831_driver = {
 108         .driver = {
 109                 .name = "rt4831",
 110                 .of_match_table = rt4831_of_match,
 111         },
 112         .probe = rt4831_probe,
 113         .remove = rt4831_remove,
 114 };
 115 module_i2c_driver(rt4831_driver);
 116
 117 MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
 118 MODULE_DESCRIPTION("Richtek RT4831 core driver");
 119 MODULE_LICENSE("GPL v2");