arch/x86/acpigen: Add new helper routines for XOR and get_rx_gpio

Add new helper function in the acpigen library, that use the underlying
soc routines.

Change-Id: I8d65699d3c806007a50adcb51c5d84567ce451b7
Signed-off-by: Rajat Jain <rajatja@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39145
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mathew King <mathewk@chromium.org>

Documentation/acpi/gpio.md

@@ -73,6 +73,15 @@ calling the platform specific acpigen_soc_{set,clear}_tx_gpio
 functions internally. Thus, all the ACPI AML calling conventions for
 the platform functions apply to these helper functions as well.
 
+3. Get Rx GPIO
+   int acpigen_get_rx_gpio(struct acpi_gpio gpio)
+
+This function takes as input, an struct acpi_gpio type and outputs
+AML code to read the *logical* value of a gpio (after taking its
+polarity into consideration), into the Local0 variable. It calls
+the platform specific acpigen_soc_read_rx_gpio() to actually read
+the raw Rx gpio value.
+
 ## Implementation Details
 
 ACPI library in coreboot will provide weak definitions for all the

src/arch/x86/acpigen.c

@@ -1203,6 +1203,15 @@ void acpigen_write_or(uint8_t arg1, uint8_t arg2, uint8_t res)
 	acpigen_emit_byte(res);
 }
 
+/* Xor (arg1, arg2, res) */
+void acpigen_write_xor(uint8_t arg1, uint8_t arg2, uint8_t res)
+{
+	acpigen_emit_byte(XOR_OP);
+	acpigen_emit_byte(arg1);
+	acpigen_emit_byte(arg2);
+	acpigen_emit_byte(res);
+}
+
 /* And (arg1, arg2, res) */
 void acpigen_write_and(uint8_t arg1, uint8_t arg2, uint8_t res)
 {
@@ -1759,6 +1768,14 @@ int acpigen_disable_tx_gpio(struct acpi_gpio *gpio)
 		return acpigen_soc_clear_tx_gpio(gpio->pins[0]);
 }
 
+void acpigen_get_rx_gpio(struct acpi_gpio *gpio)
+{
+	acpigen_soc_read_rx_gpio(gpio->pins[0]);
+
+	if (gpio->polarity == ACPI_GPIO_ACTIVE_LOW)
+		acpigen_write_xor(LOCAL0_OP, 1, LOCAL0_OP);
+}
+
 /* refer to ACPI 6.4.3.5.3 Word Address Space Descriptor section for details */
 void acpigen_resource_word(u16 res_type, u16 gen_flags, u16 type_flags, u16 gran,
 	u16 range_min, u16 range_max, u16 translation, u16 length)

src/arch/x86/include/arch/acpigen.h

@@ -361,6 +361,7 @@ void acpigen_write_sleep(uint64_t sleep_ms);
 void acpigen_write_store(void);
 void acpigen_write_store_ops(uint8_t src, uint8_t dst);
 void acpigen_write_or(uint8_t arg1, uint8_t arg2, uint8_t res);
+void acpigen_write_xor(uint8_t arg1, uint8_t arg2, uint8_t res);
 void acpigen_write_and(uint8_t arg1, uint8_t arg2, uint8_t res);
 void acpigen_write_not(uint8_t arg, uint8_t res);
 void acpigen_write_debug_string(const char *str);
@@ -472,6 +473,14 @@ int acpigen_soc_clear_tx_gpio(unsigned int gpio_num);
 int acpigen_enable_tx_gpio(struct acpi_gpio *gpio);
 int acpigen_disable_tx_gpio(struct acpi_gpio *gpio);
 
+/*
+ *  Helper function for getting a RX GPIO value based on the GPIO polarity.
+ *  The return value is stored in Local0 variable.
+ *  This function ends up calling acpigen_soc_get_rx_gpio to make callbacks
+ *  into SoC acpigen code
+ */
+void acpigen_get_rx_gpio(struct acpi_gpio *gpio);
+
 /* refer to ACPI 6.4.3.5.3 Word Address Space Descriptor section for details */
 void acpigen_resource_word(u16 res_type, u16 gen_flags, u16 type_flags, u16 gran,
 	u16 range_min, u16 range_max, u16 translation, u16 length);
@@ -481,4 +490,5 @@ void acpigen_resource_dword(u16 res_type, u16 gen_flags, u16 type_flags,
 /* refer to ACPI 6.4.3.5.1 QWord Address Space Descriptor section for details */
 void acpigen_resource_qword(u16 res_type, u16 gen_flags, u16 type_flags,
 	u64 gran, u64 range_min, u64 range_max, u64 translation, u64 length);
+
 #endif