rpi-panel-v2-regulator.c

  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(regmap, REG_PWM, 0);
 49
 50	duty = pwm_get_relative_duty_cycle(state, PWM_BL_MASK);
 51	return regmap_write(regmap, REG_PWM, 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(&i2c->dev, 1, 0);
 74	if (IS_ERR(pc))
 75		return PTR_ERR(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(regmap))
 81		return dev_err_probe(&i2c->dev, PTR_ERR(regmap), "Failed to allocate regmap\n");
 82
 83	pwmchip_set_drvdata(pc, regmap);
 84
 85	regmap_write(regmap, REG_POWERON, 0);
 86
 87	gconfig.regmap = regmap;
 88	ret = PTR_ERR_OR_ZERO(devm_gpio_regmap_register(&i2c->dev, &gconfig));
 89	if (ret)
 90		return dev_err_probe(&i2c->dev, ret, "Failed to create gpiochip\n");
 91
 92	i2c_set_clientdata(i2c, 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(regmap, REG_PWM, 0);
102	regmap_write(regmap, REG_POWERON, 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");