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
24static 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
29static 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
36static 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
45static 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(dev: &client->dev, con_id: "enable", flags: GPIOD_OUT_HIGH);
53 if (IS_ERR(ptr: enable_gpio)) {
54 dev_err(&client->dev, "Failed to get 'enable' GPIO\n");
55 return PTR_ERR(ptr: enable_gpio);
56 }
57
58 regmap = devm_regmap_init_i2c(client, &rt4831_regmap_config);
59 if (IS_ERR(ptr: regmap)) {
60 dev_err(&client->dev, "Failed to initialize regmap\n");
61 return PTR_ERR(ptr: regmap);
62 }
63
64 ret = regmap_read(map: regmap, RT4831_REG_REVISION, val: &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(map: 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(dev: &client->dev, PLATFORM_DEVID_AUTO, cells: rt4831_subdevs,
87 ARRAY_SIZE(rt4831_subdevs), NULL, irq_base: 0, NULL);
88}
89
90static void rt4831_remove(struct i2c_client *client)
91{
92 struct regmap *regmap = dev_get_regmap(dev: &client->dev, NULL);
93 int ret;
94
95 /* Disable WLED and DSV outputs */
96 ret = regmap_update_bits(map: 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
101static const struct of_device_id __maybe_unused rt4831_of_match[] = {
102 { .compatible = "richtek,rt4831", },
103 {}
104};
105MODULE_DEVICE_TABLE(of, rt4831_of_match);
106
107static 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};
115module_i2c_driver(rt4831_driver);
116
117MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
118MODULE_LICENSE("GPL v2");
119

source code of linux/drivers/mfd/rt4831.c