[PATCH v2 6/9] regulator: rpi-panel: Add GPIO control for panel and touch resets

Detlev Casanova
2022-01-21T15:21:55Z

We need independent control of the resets for the panel&bridge,
vs the touch controller.

Expose the reset lines that are on the Atmel's port C via the GPIO
API so that they can be controlled appropriately.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
---
drivers/regulator/Kconfig | 1 +
.../regulator/rpi-panel-attiny-regulator.c | 115 +++++++++++++++---
2 files changed, 98 insertions(+), 18 deletions(-)

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 1c35fed20d34..22503e4f5327 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -984,6 +984,7 @@ config REGULATOR_RASPBERRYPI_TOUCHSCREEN_ATTINY
tristate "Raspberry Pi 7-inch touchscreen panel ATTINY regulator"
depends on BACKLIGHT_CLASS_DEVICE
depends on I2C
+ depends on OF_GPIO
select REGMAP_I2C
help
This driver supports ATTINY regulator on the Raspberry Pi 7-inch
diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index 995915ca4a9b..998233f14085 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -8,6 +8,7 @@
#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>
@@ -44,10 +45,30 @@
#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 = {
@@ -58,6 +79,17 @@ static const struct regmap_config attiny_regmap_config = {
.cache_type = REGCACHE_NONE,
};

+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);
@@ -65,7 +97,7 @@ static int attiny_lcd_power_enable(struct regulator_dev *rdev)
mutex_lock(&state->lock);

/* Ensure bridge, and tp stay in reset */
- regmap_write(rdev->regmap, REG_PORTC, 0);
+ attiny_set_port_state(state, REG_PORTC, 0);
usleep_range(5000, 10000);

/* Default to the same orientation as the closed source
@@ -73,26 +105,16 @@ static int attiny_lcd_power_enable(struct regulator_dev *rdev)
* configuration will be supported using VC4's plane
* orientation bits.
*/
- regmap_write(rdev->regmap, REG_PORTA, PA_LCD_LR);
+ attiny_set_port_state(state, REG_PORTA, PA_LCD_LR);
usleep_range(5000, 10000);
- regmap_write(rdev->regmap, REG_PORTB, PB_LCD_MAIN);
+ /* 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 */
- regmap_write(rdev->regmap, REG_PORTC,
- PC_LED_EN | PC_RST_BRIDGE_N | PC_RST_LCD_N | PC_RST_TP_N);
+ attiny_set_port_state(state, REG_PORTC, PC_LED_EN);

msleep(80);

- regmap_write(rdev->regmap, REG_ADDR_H, 0x04);
- usleep_range(5000, 8000);
- regmap_write(rdev->regmap, REG_ADDR_L, 0x7c);
- usleep_range(5000, 8000);
- regmap_write(rdev->regmap, REG_WRITE_DATA_H, 0x00);
- usleep_range(5000, 8000);
- regmap_write(rdev->regmap, REG_WRITE_DATA_L, 0x00);
-
- msleep(100);
-
mutex_unlock(&state->lock);

return 0;
@@ -106,11 +128,12 @@ static int attiny_lcd_power_disable(struct regulator_dev *rdev)

regmap_write(rdev->regmap, REG_PWM, 0);
usleep_range(5000, 10000);
- regmap_write(rdev->regmap, REG_PORTA, 0);
+
+ attiny_set_port_state(state, REG_PORTA, 0);
usleep_range(5000, 10000);
- regmap_write(rdev->regmap, REG_PORTB, PB_LCD_VCC_N);
+ attiny_set_port_state(state, REG_PORTB, PB_LCD_VCC_N);
usleep_range(5000, 10000);
- regmap_write(rdev->regmap, REG_PORTC, 0);
+ attiny_set_port_state(state, REG_PORTC, 0);
msleep(30);

mutex_unlock(&state->lock);
@@ -211,6 +234,45 @@ static const struct backlight_ops attiny_bl = {
.get_brightness = attiny_get_brightness,
};

+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);
+}
+
/*
* I2C driver interface functions
*/
@@ -289,6 +351,23 @@ static int attiny_i2c_probe(struct i2c_client *i2c,

bl->props.brightness = 0xff;

+ state->gc.parent = &i2c->dev;
+ state->gc.label = i2c->name;
+ state->gc.owner = THIS_MODULE;
+ state->gc.of_node = i2c->dev.of_node;
+ 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:
--
2.34.1