regulator: rpi-panel: Add GPIO control for panel and touch resets

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>
Link: https://lore.kernel.org/r/20220124220129.158891-7-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 1c35fed20d3413b43e42eabeae12442993cdd22a..22503e4f53272a0d7092550e9c3aaf6aaf8f26c9 100644 (file)
--- 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 995915ca4a9be47bab1f67f0a283ecbf401c8397..998233f14085ed81a857960320de22fc29735af4 100644 (file)
--- 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: