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/console/Kconfig

@@ -5,6 +5,13 @@ config SERIAL_CONSOLE
 	help
 	  Send coreboot debug output to a serial port
 
+config EARLY_SERIAL_CONSOLE
+	bool
+	depends on SERIAL_CONSOLE
+	default n
+	help
+	  Use serial console during early (pre-RAM) boot stages
+
 config CONSOLE_SERIAL8250
 	bool "Serial port console output (I/O mapped, 8250-compatible)"
 	depends on SERIAL_CONSOLE

src/console/Makefile.inc

@@ -10,7 +10,7 @@ smm-y += vtxprintf.c
 smm-$(CONFIG_SMM_TSEG) += die.c
 
 romstage-y += vtxprintf.c
-romstage-$(CONFIG_CACHE_AS_RAM) += console.c
+romstage-$(CONFIG_EARLY_SERIAL_CONSOLE) += console.c
 romstage-y += post.c
 romstage-y += die.c
 

src/console/console.c

@@ -99,13 +99,15 @@ int console_tst_byte(void)
 
 #else // __PRE_RAM__   ^^^ NOT defined   vvv defined
 
+#include <uart.h>
+
 void console_init(void)
 {
 #if CONFIG_USBDEBUG
 	enable_usbdebug(CONFIG_USBDEBUG_DEFAULT_PORT);
 	early_usbdebug_init();
 #endif
-#if CONFIG_CONSOLE_SERIAL8250
+#if CONFIG_HAVE_UART_IO_MAPPED || CONFIG_HAVE_UART_MEMORY_MAPPED
 	uart_init();
 #endif
 #if CONFIG_DRIVERS_OXFORD_OXPCIE && CONFIG_CONSOLE_SERIAL8250MEM

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

src/include/uart.h

@@ -15,19 +15,29 @@
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
- *
- * FIXME(dhendrix): This file contains generic prototypes for UART functions.
- * The existing headers are too specific to the 8250, so we need a better
- * abstraction for use with non-8250 UARTs.
  */
 
+/* madness. Uarts are a mess. If you include this file, it
+ * includes ALL uart implementations which may be needed.
+ * No need to include them separately, and include this file FIRST.
+ * At least one (but at most one) of the files needs to define
+ * uart_init().
+ */
 #ifndef UART_H
 #define UART_H
 
+#if CONFIG_CONSOLE_SERIAL8250
+#include <uart8250.h>
+#endif
+
+#if CONFIG_CPU_SAMSUNG_EXYNOS5
+#include <cpu/samsung/exynos5250/uart.h>
+#endif
+
+#ifndef __ROMCC__
 unsigned char uart_rx_byte(void);
 void uart_tx_byte(unsigned char data);
 void uart_tx_flush(void);
-
-void uart_init(void);
+#endif
 
 #endif /* UART_H */

src/include/uart8250.h

@@ -120,7 +120,6 @@ unsigned char uart8250_rx_byte(unsigned base_port);
 int uart8250_can_rx_byte(unsigned base_port);
 void uart8250_tx_byte(unsigned base_port, unsigned char data);
 void uart8250_tx_flush(unsigned base_port);
-
 /* Yes it is silly to have three different uart init functions. But we used to
  * have three different sets of uart code, so it's an improvement.
  */