1 files changed, 125 insertions, 0 deletions
diff --git a/drivers/regulator/rpi-panel-v2-regulator.c b/drivers/regulator/rpi-panel-v2-regulator.c
new file mode 100644
index 000000000000..30b78aa75ee3
--- /dev/null
+++ b/drivers/regulator/rpi-panel-v2-regulator.c
@@ -0,0 +1,125 @@
+// 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");