i.MX31: Make the SPI bus and chip select configurable for MC13783

The i.MX31 has three SPI buses and each bus has several chip selects
and the MC13783 chip can be connected to any of these. The current
RTC driver for MC13783 is hardcoded for CSPI2/SS2.

This patch makes make MC13783 SPI bus and chip select configurable
via CONFIG_MC13783_SPI_BUS and CONFIG_MC13783_SPI_CS.

Signed-off-by: Magnus Lilja <lilja.magnus@gmail.com>

doc/README.mx31

@@ -0,0 +1,19 @@
+
+U-Boot for Freescale i.MX31
+
+This file contains information for the port of U-Boot to the Freescale
+i.MX31 SoC.
+
+1. CONFIGURATION OPTIONS/SETTINGS
+---------------------------------
+
+1.1 Configuration of MC13783 SPI bus
+------------------------------------
+The power management companion chip MC13783 is connected to the
+i.MX31 via an SPI bus. Use the following configuration options
+to setup the bus and chip select used for a particular board.
+
+CONFIG_MC13783_SPI_BUS	-- defines the SPI bus the MC13783 is connected to.
+			   Note that 0 is CSPI1, 1 is CSPI2 and 2 is CSPI3.
+CONFIG_MC13783_SPI_CS	-- define the chip select the MC13783 s connected to.
+

drivers/rtc/mc13783-rtc.c

@@ -34,7 +34,8 @@ int rtc_get(struct rtc_time *rtc)
 
 	if (!slave) {
 		/* FIXME: Verify the max SCK rate */
-		slave = spi_setup_slave(1, 0, 1000000,
+		slave = spi_setup_slave(CONFIG_MC13783_SPI_BUS,
+				CONFIG_MC13783_SPI_CS, 1000000,
 				SPI_MODE_2 | SPI_CS_HIGH);
 		if (!slave)
 			return -1;
@@ -83,7 +84,8 @@ int rtc_set(struct rtc_time *rtc)
 
 	if (!slave) {
 		/* FIXME: Verify the max SCK rate */
-		slave = spi_setup_slave(1, 0, 1000000,
+		slave = spi_setup_slave(CONFIG_MC13783_SPI_BUS,
+				CONFIG_MC13783_SPI_CS, 1000000,
 				SPI_MODE_2 | SPI_CS_HIGH);
 		if (!slave)
 			return -1;

include/configs/imx31_litekit.h

@@ -69,6 +69,9 @@
 #define CONFIG_DEFAULT_SPI_MODE	(SPI_MODE_2 | SPI_CS_HIGH)
 
 #define CONFIG_RTC_MC13783	1
+/* MC13783 connected to CSPI2 and SS0 */
+#define CONFIG_MC13783_SPI_BUS	1
+#define CONFIG_MC13783_SPI_CS	0
 
 /* allow to overwrite serial and ethaddr */
 #define CONFIG_ENV_OVERWRITE

include/configs/mx31ads.h

@@ -66,6 +66,9 @@
 #define CONFIG_DEFAULT_SPI_MODE	(SPI_MODE_2 | SPI_CS_HIGH)
 
 #define CONFIG_RTC_MC13783	1
+/* MC13783 connected to CSPI2 and SS0 */
+#define CONFIG_MC13783_SPI_BUS	1
+#define CONFIG_MC13783_SPI_CS	0
 
 /* allow to overwrite serial and ethaddr */
 #define CONFIG_ENV_OVERWRITE