drivers/regulator/rpi-panel-v2-regulator.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2022 Raspberry Pi Ltd.
 * Copyright (C) 2025 Marek Vasut
 */

#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/regmap.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/regmap.h>

/* I2C registers of the microcontroller. */
#define REG_ID		0x01
#define REG_POWERON	0x02
#define REG_PWM		0x03

/* Bits for poweron register */
#define LCD_RESET_BIT	BIT(0)
#define CTP_RESET_BIT	BIT(1)

/* Bits for the PWM register */
#define PWM_BL_ENABLE	BIT(7)
#define PWM_BL_MASK	GENMASK(4, 0)

/* Treat LCD_RESET and CTP_RESET as GPIOs */
#define NUM_GPIO	2

static const struct regmap_config rpi_panel_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = REG_PWM,
	.can_sleep = true,
};

static int rpi_panel_v2_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
				  const struct pwm_state *state)
{
	struct regmap *regmap = pwmchip_get_drvdata(chip);
	unsigned int duty;

	if (state->polarity != PWM_POLARITY_NORMAL)
		return -EINVAL;

	if (!state->enabled)
		return regmap_write(regmap, REG_PWM, 0);

	duty = pwm_get_relative_duty_cycle(state, PWM_BL_MASK);
	return regmap_write(regmap, REG_PWM, duty | PWM_BL_ENABLE);
}

static const struct pwm_ops rpi_panel_v2_pwm_ops = {
	.apply = rpi_panel_v2_pwm_apply,
};

/*
 * I2C driver interface functions
 */
static int rpi_panel_v2_i2c_probe(struct i2c_client *i2c)
{
	struct gpio_regmap_config gconfig = {
		.ngpio		= NUM_GPIO,
		.ngpio_per_reg	= NUM_GPIO,
		.parent		= &i2c->dev,
		.reg_set_base	= REG_POWERON,
	};
	struct regmap *regmap;
	struct pwm_chip *pc;
	int ret;

	pc = devm_pwmchip_alloc(&i2c->dev, 1, 0);
	if (IS_ERR(pc))
		return PTR_ERR(pc);

	pc->ops = &rpi_panel_v2_pwm_ops;

	regmap = devm_regmap_init_i2c(i2c, &rpi_panel_regmap_config);
	if (IS_ERR(regmap))
		return dev_err_probe(&i2c->dev, PTR_ERR(regmap), "Failed to allocate regmap\n");

	pwmchip_set_drvdata(pc, regmap);

	regmap_write(regmap, REG_POWERON, 0);

	gconfig.regmap = regmap;
	ret = PTR_ERR_OR_ZERO(devm_gpio_regmap_register(&i2c->dev, &gconfig));
	if (ret)
		return dev_err_probe(&i2c->dev, ret, "Failed to create gpiochip\n");

	i2c_set_clientdata(i2c, regmap);

	return devm_pwmchip_add(&i2c->dev, pc);
}

static void rpi_panel_v2_i2c_shutdown(struct i2c_client *client)
{
	struct regmap *regmap = i2c_get_clientdata(client);

	regmap_write(regmap, REG_PWM, 0);
	regmap_write(regmap, REG_POWERON, 0);
}

static const struct of_device_id rpi_panel_v2_dt_ids[] = {
	{ .compatible = "raspberrypi,touchscreen-panel-regulator-v2" },
	{ },
};
MODULE_DEVICE_TABLE(of, rpi_panel_v2_dt_ids);

static struct i2c_driver rpi_panel_v2_regulator_driver = {
	.driver = {
		.name = "rpi_touchscreen_v2",
		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
		.of_match_table = rpi_panel_v2_dt_ids,
	},
	.probe = rpi_panel_v2_i2c_probe,
	.shutdown = rpi_panel_v2_i2c_shutdown,
};

module_i2c_driver(rpi_panel_v2_regulator_driver);

MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.com>");
MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch V2 touchscreen");
MODULE_LICENSE("GPL");