1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2022 Raspberry Pi Ltd.
4 * Copyright (C) 2025 Marek Vasut
5 */
6
7#include <linux/err.h>
8#include <linux/gpio/driver.h>
9#include <linux/gpio/regmap.h>
10#include <linux/i2c.h>
11#include <linux/module.h>
12#include <linux/pwm.h>
13#include <linux/regmap.h>
14
15/* I2C registers of the microcontroller. */
16#define REG_ID 0x01
17#define REG_POWERON 0x02
18#define REG_PWM 0x03
19
20/* Bits for poweron register */
21#define LCD_RESET_BIT BIT(0)
22#define CTP_RESET_BIT BIT(1)
23
24/* Bits for the PWM register */
25#define PWM_BL_ENABLE BIT(7)
26#define PWM_BL_MASK GENMASK(4, 0)
27
28/* Treat LCD_RESET and CTP_RESET as GPIOs */
29#define NUM_GPIO 2
30
31static const struct regmap_config rpi_panel_regmap_config = {
32 .reg_bits = 8,
33 .val_bits = 8,
34 .max_register = REG_PWM,
35 .can_sleep = true,
36};
37
38static int rpi_panel_v2_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
39 const struct pwm_state *state)
40{
41 struct regmap *regmap = pwmchip_get_drvdata(chip);
42 unsigned int duty;
43
44 if (state->polarity != PWM_POLARITY_NORMAL)
45 return -EINVAL;
46
47 if (!state->enabled)
48 return regmap_write(map: regmap, REG_PWM, val: 0);
49
50 duty = pwm_get_relative_duty_cycle(state, PWM_BL_MASK);
51 return regmap_write(map: regmap, REG_PWM, val: duty | PWM_BL_ENABLE);
52}
53
54static const struct pwm_ops rpi_panel_v2_pwm_ops = {
55 .apply = rpi_panel_v2_pwm_apply,
56};
57
58/*
59 * I2C driver interface functions
60 */
61static int rpi_panel_v2_i2c_probe(struct i2c_client *i2c)
62{
63 struct gpio_regmap_config gconfig = {
64 .ngpio = NUM_GPIO,
65 .ngpio_per_reg = NUM_GPIO,
66 .parent = &i2c->dev,
67 .reg_set_base = REG_POWERON,
68 };
69 struct regmap *regmap;
70 struct pwm_chip *pc;
71 int ret;
72
73 pc = devm_pwmchip_alloc(parent: &i2c->dev, npwm: 1, sizeof_priv: 0);
74 if (IS_ERR(ptr: pc))
75 return PTR_ERR(ptr: pc);
76
77 pc->ops = &rpi_panel_v2_pwm_ops;
78
79 regmap = devm_regmap_init_i2c(i2c, &rpi_panel_regmap_config);
80 if (IS_ERR(ptr: regmap))
81 return dev_err_probe(dev: &i2c->dev, err: PTR_ERR(ptr: regmap), fmt: "Failed to allocate regmap\n");
82
83 pwmchip_set_drvdata(chip: pc, data: regmap);
84
85 regmap_write(map: regmap, REG_POWERON, val: 0);
86
87 gconfig.regmap = regmap;
88 ret = PTR_ERR_OR_ZERO(ptr: devm_gpio_regmap_register(dev: &i2c->dev, config: &gconfig));
89 if (ret)
90 return dev_err_probe(dev: &i2c->dev, err: ret, fmt: "Failed to create gpiochip\n");
91
92 i2c_set_clientdata(client: i2c, data: regmap);
93
94 return devm_pwmchip_add(&i2c->dev, pc);
95}
96
97static void rpi_panel_v2_i2c_shutdown(struct i2c_client *client)
98{
99 struct regmap *regmap = i2c_get_clientdata(client);
100
101 regmap_write(map: regmap, REG_PWM, val: 0);
102 regmap_write(map: regmap, REG_POWERON, val: 0);
103}
104
105static const struct of_device_id rpi_panel_v2_dt_ids[] = {
106 { .compatible = "raspberrypi,touchscreen-panel-regulator-v2" },
107 { },
108};
109MODULE_DEVICE_TABLE(of, rpi_panel_v2_dt_ids);
110
111static struct i2c_driver rpi_panel_v2_regulator_driver = {
112 .driver = {
113 .name = "rpi_touchscreen_v2",
114 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
115 .of_match_table = rpi_panel_v2_dt_ids,
116 },
117 .probe = rpi_panel_v2_i2c_probe,
118 .shutdown = rpi_panel_v2_i2c_shutdown,
119};
120
121module_i2c_driver(rpi_panel_v2_regulator_driver);
122
123MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.com>");
124MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch V2 touchscreen");
125MODULE_LICENSE("GPL");
126

source code of linux/drivers/regulator/rpi-panel-v2-regulator.c