2 files changed, 116 insertions, 0 deletions

diff --git a/src/arch/x86/acpi_device.c b/src/arch/x86/acpi_device.c
index 3c0230fae2..073b938101 100644
--- a/src/arch/x86/acpi_device.c
+++ b/src/arch/x86/acpi_device.c
@@ -381,3 +381,75 @@ void acpi_device_write_i2c(const struct acpi_i2c *i2c)
 	/* Fill in I2C Descriptor Length */
 	acpi_device_fill_len(desc_length);
 }
+
+/* ACPI 6.1 section 6.4.3.8.2.2 - SpiSerialBus() */
+void acpi_device_write_spi(const struct acpi_spi *spi)
+{
+	void *desc_length, *type_length;
+	uint16_t flags = 0;
+
+	/* Byte 0: Descriptor Type */
+	acpigen_emit_byte(ACPI_DESCRIPTOR_SERIAL_BUS);
+
+	/* Byte 1+2: Length (filled in later) */
+	desc_length = acpi_device_write_zero_len();
+
+	/* Byte 3: Revision ID */
+	acpigen_emit_byte(ACPI_SERIAL_BUS_REVISION_ID);
+
+	/* Byte 4: Resource Source Index is Reserved */
+	acpigen_emit_byte(0);
+
+	/* Byte 5: Serial Bus Type is SPI */
+	acpigen_emit_byte(ACPI_SERIAL_BUS_TYPE_SPI);
+
+	/*
+	 * Byte 6: Flags
+	 *  [7:2]: 0 => Reserved
+	 *    [1]: 1 => ResourceConsumer
+	 *    [0]: 0 => ControllerInitiated
+	 */
+	acpigen_emit_byte(1 << 1);
+
+	/*
+	 * Byte 7-8: Type Specific Flags
+	 *   [15:2]: 0 => Reserved
+	 *      [1]: 0 => ActiveLow, 1 => ActiveHigh
+	 *      [0]: 0 => FourWire, 1 => ThreeWire
+	 */
+	if (spi->wire_mode == SPI_3_WIRE_MODE)
+		flags |= 1 << 0;
+	if (spi->device_select_polarity == SPI_POLARITY_HIGH)
+		flags |= 1 << 1;
+	acpigen_emit_word(flags);
+
+	/* Byte 9: Type Specific Revision ID */
+	acpigen_emit_byte(ACPI_SERIAL_BUS_REVISION_ID);
+
+	/* Byte 10-11: SPI Type Data Length */
+	type_length = acpi_device_write_zero_len();
+
+	/* Byte 12-15: Connection Speed */
+	acpigen_emit_dword(spi->speed);
+
+	/* Byte 16: Data Bit Length */
+	acpigen_emit_byte(spi->data_bit_length);
+
+	/* Byte 17: Clock Phase */
+	acpigen_emit_byte(spi->clock_phase);
+
+	/* Byte 18: Clock Polarity */
+	acpigen_emit_byte(spi->clock_polarity);
+
+	/* Byte 19-20: Device Selection */
+	acpigen_emit_word(spi->device_select);
+
+	/* Fill in Type Data Length */
+	acpi_device_fill_len(type_length);
+
+	/* Byte 21+: ResourceSource String */
+	acpigen_emit_string(spi->resource);
+
+	/* Fill in SPI Descriptor Length */
+	acpi_device_fill_len(desc_length);
+}
diff --git a/src/arch/x86/include/arch/acpi_device.h b/src/arch/x86/include/arch/acpi_device.h
index 7b5001f65a..dc7f26c14b 100644
--- a/src/arch/x86/include/arch/acpi_device.h
+++ b/src/arch/x86/include/arch/acpi_device.h
@@ -164,6 +164,7 @@ void acpi_device_write_gpio(const struct acpi_gpio *gpio);
  */
 
 #define ACPI_SERIAL_BUS_TYPE_I2C	1
+#define ACPI_SERIAL_BUS_TYPE_SPI	2
 #define ACPI_SERIAL_BUS_REVISION_ID	1
 
 /*
@@ -184,4 +185,47 @@ struct acpi_i2c {
 /* Write I2cSerialBus() descriptor to SSDT AML output */
 void acpi_device_write_i2c(const struct acpi_i2c *i2c);
 
+/*
+ * ACPI SPI Bus
+ */
+
+enum spi_clock_phase {
+	SPI_CLOCK_PHASE_FIRST,
+	SPI_CLOCK_PHASE_SECOND
+};
+
+/* SPI Flags bit 0 */
+enum spi_wire_mode {
+	SPI_4_WIRE_MODE,
+	SPI_3_WIRE_MODE
+};
+
+/* SPI Flags bit 1 */
+enum spi_polarity {
+	SPI_POLARITY_LOW,
+	SPI_POLARITY_HIGH
+};
+
+struct acpi_spi {
+	/* Device selection */
+	uint16_t device_select;
+	/* Device selection line is active high or low */
+	enum spi_polarity device_select_polarity;
+	/* 3 or 4 wire SPI connection */
+	enum spi_wire_mode wire_mode;
+	/* Connection speed in HZ */
+	unsigned int speed;
+	/* Size in bits of smallest transfer unit */
+	u8 data_bit_length;
+	/* Phase of clock pulse on which to capture data */
+	enum spi_clock_phase clock_phase;
+	/* Indicate if clock is high or low during first phase */
+	enum spi_polarity clock_polarity;
+	/* Reference to SPI controller */
+	const char *resource;
+};
+
+/* Write SPI Bus descriptor to SSDT AML output */
+void acpi_device_write_spi(const struct acpi_spi *spi);
+
 #endif