drivers/i2c/generic: Enable support for adding PowerResource for device

Add support to allow a device to define PowerResource in its SSDT AML
code. PowerResouce ACPI generation expects SoC to define the
callbacks for generating AML code for GPIO manipulation.

Device requiring PowerResource needs to define following parameters:
1. Reset GPIO - Optional, GPIO to put device into reset or take it out
of reset.
2. Reset delay - Delay after reset GPIO is de-asserted (default 0).
3. Enable GPIO - Optional, GPIO to enabled device.
4. Enable delay - Delay after enable GPIO is asserted (default 0).

BUG=chrome-os-partner:55988

Change-Id: Ieb2dd95fc1f555f5de66f3dda425172ac5b75dad
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17081
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins)

2 files changed, 52 insertions, 0 deletions

diff --git a/src/drivers/i2c/generic/chip.h b/src/drivers/i2c/generic/chip.h
index d84097f6c6..e84fc38df9 100644
--- a/src/drivers/i2c/generic/chip.h
+++ b/src/drivers/i2c/generic/chip.h
@@ -22,4 +22,13 @@ struct drivers_i2c_generic_config {
 	/* GPIO used to indicate if this device is present */
 	unsigned device_present_gpio;
 	unsigned device_present_gpio_invert;
+
+	/* GPIO used to take device out of reset or to put it into reset. */
+        unsigned reset_gpio;
+	/* Delay to be inserted after device is taken out of reset. */
+	unsigned reset_delay_ms;
+	/* GPIO used to enable device. */
+	unsigned enable_gpio;
+	/* Delay to be inserted after device is enabled. */
+	unsigned enable_delay_ms;
 };
diff --git a/src/drivers/i2c/generic/generic.c b/src/drivers/i2c/generic/generic.c
index c11a889d5b..34fbf77a3e 100644
--- a/src/drivers/i2c/generic/generic.c
+++ b/src/drivers/i2c/generic/generic.c
@@ -25,6 +25,46 @@
 #include "chip.h"
 
 #if IS_ENABLED(CONFIG_HAVE_ACPI_TABLES)
+
+static void i2c_generic_add_power_res(struct drivers_i2c_generic_config *config)
+{
+	const char *power_res_dev_states[] = { "_PR0", "_PR3" };
+
+	if (!config->reset_gpio && !config->enable_gpio)
+		return;
+
+	/* PowerResource (PRIC, 0, 0) */
+	acpigen_write_power_res("PRIC", 0, 0, power_res_dev_states,
+				ARRAY_SIZE(power_res_dev_states));
+
+	/* Method (_STA, 0, NotSerialized) { Return (0x1) } */
+	acpigen_write_STA(0x1);
+
+	/* Method (_ON, 0, Serialized) */
+	acpigen_write_method_serialized("_ON", 0);
+	if (config->reset_gpio)
+		acpigen_soc_set_tx_gpio(config->reset_gpio);
+	if (config->enable_gpio) {
+		acpigen_soc_set_tx_gpio(config->enable_gpio);
+		acpigen_write_sleep(config->enable_delay_ms);
+	}
+	if (config->reset_gpio) {
+		acpigen_soc_clear_tx_gpio(config->reset_gpio);
+		acpigen_write_sleep(config->reset_delay_ms);
+	}
+	acpigen_pop_len();		/* _ON method */
+
+	/* Method (_OFF, 0, Serialized) */
+	acpigen_write_method_serialized("_OFF", 0);
+	if (config->reset_gpio)
+		acpigen_soc_set_tx_gpio(config->reset_gpio);
+	if (config->enable_gpio)
+		acpigen_soc_clear_tx_gpio(config->enable_gpio);
+	acpigen_pop_len();		/* _OFF method */
+
+	acpigen_pop_len();		/* PowerResource PRIC */
+}
+
 static void i2c_generic_fill_ssdt(struct device *dev)
 {
 	struct drivers_i2c_generic_config *config = dev->chip_info;
@@ -72,6 +112,9 @@ static void i2c_generic_fill_ssdt(struct device *dev)
 		acpi_dp_write(dsd);
 	}
 
+	/* Power Resource */
+	i2c_generic_add_power_res(config);
+
 	acpigen_pop_len(); /* Device */
 	acpigen_pop_len(); /* Scope */