make early serial console support more generic

This patch makes pre-RAM serial init more generic, particularly for
platforms which do not necessarily need cache-as-RAM in order to use
the serial console and do not have a standard 8250 serial port.

This adds a Kconfig variable to set romstage-* for very early serial
console init. The current method assumes that cache-as-RAM should
enable this, so to maintain compatibility selecting CACHE_AS_RAM will
also select EARLY_SERIAL_CONSOLE.

The UART code structure needs some rework, but the use of ROMCC,
romstage, and then ramstage makes things complex.

uart.h now includes all .h files for all uarts. All 2 of them.
This is actually a simplifying change.

Change-Id: I089e7af633c227baf3c06c685f005e9d0e4b38ce
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-on: http://review.coreboot.org/2086
Tested-by: build bot (Jenkins)

src/cpu/Kconfig

@@ -16,6 +16,7 @@ source src/cpu/x86/Kconfig
 
 config CACHE_AS_RAM
 	bool
+	select EARLY_SERIAL_CONSOLE
 	default !ROMCC
 
 config DCACHE_RAM_BASE

src/cpu/samsung/Kconfig

@@ -5,6 +5,7 @@ config CPU_SAMSUNG_EXYNOS
 config CPU_SAMSUNG_EXYNOS5
 	depends on ARCH_ARMV7
 	select CPU_SAMSUNG_EXYNOS
+	select EARLY_SERIAL_CONSOLE
 	bool
 	default n
 

src/cpu/samsung/exynos5250/uart.c

@@ -23,6 +23,7 @@
 
 //#include <common.h>
 //#include <linux/compiler.h>
+#include <types.h>
 #include <uart.h>
 #include <arch/io.h>
 //#include <asm/arch-exynos/spl.h>
@@ -34,7 +35,6 @@
 
 #include <cpu/samsung/exynos5-common/exynos5-common.h>
 #include <cpu/samsung/exynos5250/clk.h>
-#include <cpu/samsung/exynos5250/uart.h>
 
 #define RX_FIFO_COUNT_MASK	0xff
 #define RX_FIFO_FULL_MASK	(1 << 8)
@@ -218,12 +218,12 @@ static const struct console_driver exynos5_uart_console __console = {
 //unsigned char (*uart_rx_byte)(unsigned base_port) = exynos5_uart_rx_byte;
 //void (*uart_tx_byte)(unsigned base_port, unsigned char data) = exynos5_uart_tx_byte;
 /* FIXME: trivial wrappers */
-void uart_init()
+void uart_init(void)
 {
 	exynos5_init_dev();
 }
 
-unsigned char uart_rx_byte()
+unsigned char uart_rx_byte(void)
 {
 	return exynos5_uart_rx_byte();
 }

src/cpu/samsung/exynos5250/uart.h

@@ -68,4 +68,5 @@ static inline int s5p_uart_divslot(void)
 	return 0;
 }
 
+void uart_init(void);
 #endif