1 files changed, 410 insertions, 0 deletions

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
new file mode 100644
index 000000000..308f79729
--- /dev/null
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -0,0 +1,410 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Marek Vasut <marex@denx.de>
+ *
+ * Based on rpi_touchscreen.c by Eric Anholt <eric@anholt.net>
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/slab.h>
+
+/* I2C registers of the Atmel microcontroller. */
+#define REG_ID		0x80
+#define REG_PORTA	0x81
+#define REG_PORTB	0x82
+#define REG_PORTC	0x83
+#define REG_POWERON	0x85
+#define REG_PWM		0x86
+#define REG_ADDR_L	0x8c
+#define REG_ADDR_H	0x8d
+#define REG_WRITE_DATA_H	0x90
+#define REG_WRITE_DATA_L	0x91
+
+#define PA_LCD_DITHB		BIT(0)
+#define PA_LCD_MODE		BIT(1)
+#define PA_LCD_LR		BIT(2)
+#define PA_LCD_UD		BIT(3)
+
+#define PB_BRIDGE_PWRDNX_N	BIT(0)
+#define PB_LCD_VCC_N		BIT(1)
+#define PB_LCD_MAIN		BIT(7)
+
+#define PC_LED_EN		BIT(0)
+#define PC_RST_TP_N		BIT(1)
+#define PC_RST_LCD_N		BIT(2)
+#define PC_RST_BRIDGE_N		BIT(3)
+
+enum gpio_signals {
+	RST_BRIDGE_N,	/* TC358762 bridge reset */
+	RST_TP_N,	/* Touch controller reset */
+	NUM_GPIO
+};
+
+struct gpio_signal_mappings {
+	unsigned int reg;
+	unsigned int mask;
+};
+
+static const struct gpio_signal_mappings mappings[NUM_GPIO] = {
+	[RST_BRIDGE_N] = { REG_PORTC, PC_RST_BRIDGE_N | PC_RST_LCD_N  },
+	[RST_TP_N] = { REG_PORTC, PC_RST_TP_N },
+};
+
+struct attiny_lcd {
+	/* lock to serialise overall accesses to the Atmel */
+	struct mutex	lock;
+	struct regmap	*regmap;
+	bool gpio_states[NUM_GPIO];
+	u8 port_states[3];
+
+	struct gpio_chip gc;
+};
+
+static const struct regmap_config attiny_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.disable_locking = 1,
+	.max_register = REG_WRITE_DATA_L,
+	.cache_type = REGCACHE_RBTREE,
+};
+
+static int attiny_set_port_state(struct attiny_lcd *state, int reg, u8 val)
+{
+	state->port_states[reg - REG_PORTA] = val;
+	return regmap_write(state->regmap, reg, val);
+};
+
+static u8 attiny_get_port_state(struct attiny_lcd *state, int reg)
+{
+	return state->port_states[reg - REG_PORTA];
+};
+
+static int attiny_lcd_power_enable(struct regulator_dev *rdev)
+{
+	struct attiny_lcd *state = rdev_get_drvdata(rdev);
+
+	mutex_lock(&state->lock);
+
+	/* Ensure bridge, and tp stay in reset */
+	attiny_set_port_state(state, REG_PORTC, 0);
+	usleep_range(5000, 10000);
+
+	/* Default to the same orientation as the closed source
+	 * firmware used for the panel.  Runtime rotation
+	 * configuration will be supported using VC4's plane
+	 * orientation bits.
+	 */
+	attiny_set_port_state(state, REG_PORTA, PA_LCD_LR);
+	usleep_range(5000, 10000);
+	/* Main regulator on, and power to the panel (LCD_VCC_N) */
+	attiny_set_port_state(state, REG_PORTB, PB_LCD_MAIN);
+	usleep_range(5000, 10000);
+	/* Bring controllers out of reset */
+	attiny_set_port_state(state, REG_PORTC, PC_LED_EN);
+
+	msleep(80);
+
+	mutex_unlock(&state->lock);
+
+	return 0;
+}
+
+static int attiny_lcd_power_disable(struct regulator_dev *rdev)
+{
+	struct attiny_lcd *state = rdev_get_drvdata(rdev);
+
+	mutex_lock(&state->lock);
+
+	regmap_write(rdev->regmap, REG_PWM, 0);
+	usleep_range(5000, 10000);
+
+	attiny_set_port_state(state, REG_PORTA, 0);
+	usleep_range(5000, 10000);
+	attiny_set_port_state(state, REG_PORTB, PB_LCD_VCC_N);
+	usleep_range(5000, 10000);
+	attiny_set_port_state(state, REG_PORTC, 0);
+	msleep(30);
+
+	mutex_unlock(&state->lock);
+
+	return 0;
+}
+
+static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
+{
+	struct attiny_lcd *state = rdev_get_drvdata(rdev);
+	unsigned int data;
+	int ret, i;
+
+	mutex_lock(&state->lock);
+
+	for (i = 0; i < 10; i++) {
+		ret = regmap_read(rdev->regmap, REG_PORTC, &data);
+		if (!ret)
+			break;
+		usleep_range(10000, 12000);
+	}
+
+	mutex_unlock(&state->lock);
+
+	if (ret < 0)
+		return ret;
+
+	return data & PC_RST_BRIDGE_N;
+}
+
+static const struct regulator_init_data attiny_regulator_default = {
+	.constraints = {
+		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
+	},
+};
+
+static const struct regulator_ops attiny_regulator_ops = {
+	.enable = attiny_lcd_power_enable,
+	.disable = attiny_lcd_power_disable,
+	.is_enabled = attiny_lcd_power_is_enabled,
+};
+
+static const struct regulator_desc attiny_regulator = {
+	.name	= "tc358762-power",
+	.ops	= &attiny_regulator_ops,
+	.type	= REGULATOR_VOLTAGE,
+	.owner	= THIS_MODULE,
+};
+
+static int attiny_update_status(struct backlight_device *bl)
+{
+	struct attiny_lcd *state = bl_get_data(bl);
+	struct regmap *regmap = state->regmap;
+	int brightness = backlight_get_brightness(bl);
+	int ret, i;
+
+	mutex_lock(&state->lock);
+
+	for (i = 0; i < 10; i++) {
+		ret = regmap_write(regmap, REG_PWM, brightness);
+		if (!ret)
+			break;
+	}
+
+	mutex_unlock(&state->lock);
+
+	return ret;
+}
+
+static const struct backlight_ops attiny_bl = {
+	.update_status	= attiny_update_status,
+};
+
+static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
+{
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
+{
+	struct attiny_lcd *state = gpiochip_get_data(gc);
+	u8 last_val;
+
+	if (off >= NUM_GPIO)
+		return;
+
+	mutex_lock(&state->lock);
+
+	last_val = attiny_get_port_state(state, mappings[off].reg);
+	if (val)
+		last_val |= mappings[off].mask;
+	else
+		last_val &= ~mappings[off].mask;
+
+	attiny_set_port_state(state, mappings[off].reg, last_val);
+
+	if (off == RST_BRIDGE_N && val) {
+		usleep_range(5000, 8000);
+		regmap_write(state->regmap, REG_ADDR_H, 0x04);
+		usleep_range(5000, 8000);
+		regmap_write(state->regmap, REG_ADDR_L, 0x7c);
+		usleep_range(5000, 8000);
+		regmap_write(state->regmap, REG_WRITE_DATA_H, 0x00);
+		usleep_range(5000, 8000);
+		regmap_write(state->regmap, REG_WRITE_DATA_L, 0x00);
+
+		msleep(100);
+	}
+
+	mutex_unlock(&state->lock);
+}
+
+static int attiny_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)
+{
+	struct i2c_msg msgs[1];
+	u8 addr_buf[1] = { reg };
+	u8 data_buf[1] = { 0, };
+	int ret;
+
+	/* Write register address */
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].len = ARRAY_SIZE(addr_buf);
+	msgs[0].buf = addr_buf;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs))
+		return -EIO;
+
+	usleep_range(5000, 10000);
+
+	/* Read data from register */
+	msgs[0].addr = client->addr;
+	msgs[0].flags = I2C_M_RD;
+	msgs[0].len = 1;
+	msgs[0].buf = data_buf;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs))
+		return -EIO;
+
+	*buf = data_buf[0];
+	return 0;
+}
+
+/*
+ * I2C driver interface functions
+ */
+static int attiny_i2c_probe(struct i2c_client *i2c,
+		const struct i2c_device_id *id)
+{
+	struct backlight_properties props = { };
+	struct regulator_config config = { };
+	struct backlight_device *bl;
+	struct regulator_dev *rdev;
+	struct attiny_lcd *state;
+	struct regmap *regmap;
+	unsigned int data;
+	int ret;
+
+	state = devm_kzalloc(&i2c->dev, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	mutex_init(&state->lock);
+	i2c_set_clientdata(i2c, state);
+
+	regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
+			ret);
+		goto error;
+	}
+
+	ret = attiny_i2c_read(i2c, REG_ID, &data);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
+		goto error;
+	}
+
+	switch (data) {
+	case 0xde: /* ver 1 */
+	case 0xc3: /* ver 2 */
+		break;
+	default:
+		dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
+		ret = -ENODEV;
+		goto error;
+	}
+
+	regmap_write(regmap, REG_POWERON, 0);
+	msleep(30);
+	regmap_write(regmap, REG_PWM, 0);
+
+	config.dev = &i2c->dev;
+	config.regmap = regmap;
+	config.of_node = i2c->dev.of_node;
+	config.init_data = &attiny_regulator_default;
+	config.driver_data = state;
+
+	rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
+	if (IS_ERR(rdev)) {
+		dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
+		ret = PTR_ERR(rdev);
+		goto error;
+	}
+
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = 0xff;
+
+	state->regmap = regmap;
+
+	bl = devm_backlight_device_register(&i2c->dev, dev_name(&i2c->dev),
+					    &i2c->dev, state, &attiny_bl,
+					    &props);
+	if (IS_ERR(bl)) {
+		ret = PTR_ERR(bl);
+		goto error;
+	}
+
+	bl->props.brightness = 0xff;
+
+	state->gc.parent = &i2c->dev;
+	state->gc.label = i2c->name;
+	state->gc.owner = THIS_MODULE;
+	state->gc.base = -1;
+	state->gc.ngpio = NUM_GPIO;
+
+	state->gc.set = attiny_gpio_set;
+	state->gc.get_direction = attiny_gpio_get_direction;
+	state->gc.can_sleep = true;
+
+	ret = devm_gpiochip_add_data(&i2c->dev, &state->gc, state);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to create gpiochip: %d\n", ret);
+		goto error;
+	}
+
+	return 0;
+
+error:
+	mutex_destroy(&state->lock);
+
+	return ret;
+}
+
+static void attiny_i2c_remove(struct i2c_client *client)
+{
+	struct attiny_lcd *state = i2c_get_clientdata(client);
+
+	mutex_destroy(&state->lock);
+}
+
+static const struct of_device_id attiny_dt_ids[] = {
+	{ .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, attiny_dt_ids);
+
+static struct i2c_driver attiny_regulator_driver = {
+	.driver = {
+		.name = "rpi_touchscreen_attiny",
+		.of_match_table = of_match_ptr(attiny_dt_ids),
+	},
+	.probe = attiny_i2c_probe,
+	.remove	= attiny_i2c_remove,
+};
+
+module_i2c_driver(attiny_regulator_driver);
+
+MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
+MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
+MODULE_LICENSE("GPL v2");