DaVinci: Support different console UART base addresses

The davinci pre-kernel boot code assumes that all platforms use
the same UART base address for the console.  That assumption
is not longer valid with some newer SoCs so determine the console
UART base address from the machine number passed in from u-boot.
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/boot/compressed/Makefile

@@ -48,6 +48,10 @@ else
 endif
 endif
 
+ifeq ($(CONFIG_MACH_DAVINCI_EVM),y)
+OBJS		+= head-davinci.o
+endif
+
 #
 # We now have a PIC decompressor implementation.  Decompressors running
 # from RAM should not define ZTEXTADDR.  Decompressors running directly

arch/arm/boot/compressed/head-davinci.S

+/*
+ * DaVinci (and relatives) specific tweaks.
+ * This is merged into head.S by the linker.
+ */
+
+#include <linux/linkage.h>
+#include <asm/mach-types.h>
+
+		.section        ".start", "ax"
+
+__davinci_start:
+		/* Save machine number for later conditional code */
+		adr	r0, davinci_machine_no
+		str	r7, [r0]
+
+		.text
+		.globl	davinci_machine_no
+davinci_machine_no:
+		.word	0x00000000

arch/arm/mach-davinci/include/mach/uncompress.h

@@ -13,11 +13,27 @@
 #include <linux/serial_reg.h>
 #include <mach/serial.h>
 
+#include <asm/mach-types.h>
+
+extern u32 davinci_machine_no;
+
+static u8 first_time = 1;
+static u32 *uart;
+
+static u32 *get_uart_base(void)
+{
+	/* Add logic here for new platforms */
+	return (u32 *)DAVINCI_UART0_BASE;
+}
+
 /* PORT_16C550A, in polled non-fifo mode */
 
 static void putc(char c)
 {
-	volatile u32 *uart = (volatile void *) DAVINCI_UART0_BASE;
+	if (first_time) {
+		uart = get_uart_base();
+		first_time = 0;
+	}
 
 	while (!(uart[UART_LSR] & UART_LSR_THRE))
 		barrier();
@@ -26,7 +42,11 @@ static void putc(char c)
 
 static inline void flush(void)
 {
-	volatile u32 *uart = (volatile void *) DAVINCI_UART0_BASE;
+	if (first_time) {
+		uart = get_uart_base();
+		first_time = 0;
+	}
+
 	while (!(uart[UART_LSR] & UART_LSR_THRE))
 		barrier();
 }