spi: Add function callback to get configuration of SPI bus

Add a new callback to spi_ctrlr structure - get_config - to obtain
configuration of SPI bus from the controller driver. Also, move common
config definitions from acpi_device.h to spi-generic.h

BUG=chrome-os-partner:59832
BRANCH=None
TEST=Compiles successfully

Change-Id: I412c8c70167d18058a32041c2310bc1c884043ce
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/18337
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/arch/x86/include/arch/acpi_device.h

@@ -18,6 +18,7 @@
 
 #include <device/i2c.h>
 #include <stdint.h>
+#include <spi-generic.h>
 
 #define ACPI_DESCRIPTOR_LARGE		(1 << 7)
 #define ACPI_DESCRIPTOR_INTERRUPT	(ACPI_DESCRIPTOR_LARGE | 9)
@@ -216,23 +217,6 @@ 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;

src/drivers/spi/spi-generic.c

@@ -88,6 +88,16 @@ int spi_xfer(const struct spi_slave *slave, const void *dout, size_t bytesout,
 	return -1;
 }
 
+int spi_get_config(const struct spi_slave *slave, struct spi_cfg *cfg)
+{
+	const struct spi_ctrlr *ctrlr = slave->ctrlr;
+
+	if (ctrlr && ctrlr->get_config)
+		return ctrlr->get_config(slave, cfg);
+
+	return -1;
+}
+
 void __attribute__((weak)) spi_init(void)
 {
 	/* Default weak implementation - do nothing. */

src/include/spi-generic.h

@@ -59,9 +59,38 @@ struct spi_op {
 	enum spi_op_status status;
 };
 
+enum spi_clock_phase {
+	SPI_CLOCK_PHASE_FIRST,
+	SPI_CLOCK_PHASE_SECOND
+};
+
+enum spi_wire_mode {
+	SPI_4_WIRE_MODE,
+	SPI_3_WIRE_MODE
+};
+
+enum spi_polarity {
+	SPI_POLARITY_LOW,
+	SPI_POLARITY_HIGH
+};
+
+struct spi_cfg {
+	/* CLK phase - 0: Phase first, 1: Phase second */
+	enum spi_clock_phase clk_phase;
+	/* CLK polarity - 0: Low, 1: High */
+	enum spi_polarity clk_polarity;
+	/* CS polarity - 0: Low, 1: High */
+	enum spi_polarity cs_polarity;
+	/* Wire mode - 0: 4-wire, 1: 3-wire */
+	enum spi_wire_mode wire_mode;
+	/* Data bit length. */
+	unsigned int data_bit_length;
+};
+
 /*-----------------------------------------------------------------------
  * Representation of a SPI contoller.
  *
+ * get_config:	Get configuration of SPI bus
  * claim_bus:	Claim SPI bus and prepare for communication.
  * release_bus: Release SPI bus.
  * setup:	Setup given SPI device bus.
@@ -69,6 +98,8 @@ struct spi_op {
  * xfer_vector: Vector of SPI transfer operations.
  */
 struct spi_ctrlr {
+	int (*get_config)(const struct spi_slave *slave,
+			struct spi_cfg *cfg);
 	int (*claim_bus)(const struct spi_slave *slave);
 	void (*release_bus)(const struct spi_slave *slave);
 	int (*setup)(const struct spi_slave *slave);
@@ -101,6 +132,17 @@ extern const size_t spi_ctrlr_bus_map_count;
  */
 void spi_init(void);
 
+/*
+ * Get configuration of SPI bus.
+ *
+ * slave:     Pointer to slave structure.
+ * cfg:       Pointer to SPI configuration that needs to be filled.
+ *
+ * Returns:
+ * 0 on success, -1 on error
+ */
+int spi_get_config(const struct spi_slave *slave, struct spi_cfg *cfg);
+
 /*-----------------------------------------------------------------------
  * Set up communications parameters for a SPI slave.
  *