Enable the debug UART and emit a single 'a' early in the init sequence to
show that it is working.
Unfortunately the debug UART implementation needs a stack to work. I cannot
seem to remove this limitation as the absolute 'jmp %eax' instruction goes
off into the weeds.
So this means that the character output cannot be any earlier than
car_init_ret, where memory is available for a stack.
Signed-off-by: Simon Glass <s...@chromium.org>
---
arch/x86/cpu/start.S | 4 ++++
configs/minnowmax_defconfig | 4 ++++
include/debug_uart.h | 20 ++++++++++----------
3 files changed, 18 insertions(+), 10 deletions(-)
diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
index 2e5f9da..c6965b2 100644
--- a/arch/x86/cpu/start.S
+++ b/arch/x86/cpu/start.S
@@ -109,6 +109,10 @@ car_init_ret:
andl $0xfffffff0, %esp
post_code(POST_START_STACK)
+ call debug_uart_init
+ mov $'a', %eax
+ call printch
+
/* Zero the global data since it won't happen later */
xorl %eax, %eax
movl $GENERATED_GBL_DATA_SIZE, %ecx
diff --git a/configs/minnowmax_defconfig b/configs/minnowmax_defconfig
index 744aca3..14e21fa 100644
--- a/configs/minnowmax_defconfig
+++ b/configs/minnowmax_defconfig
@@ -12,3 +12,7 @@ CONFIG_CMD_CPU=y
CONFIG_CMD_NET=y
CONFIG_OF_CONTROL=y
CONFIG_CPU=y
+CONFIG_DEBUG_UART=y
+CONFIG_DEBUG_UART_NS16550=y
+CONFIG_DEBUG_UART_BASE=0x3f8
+CONFIG_DEBUG_UART_CLOCK=1843200
diff --git a/include/debug_uart.h b/include/debug_uart.h
index f56797b..0acc91c 100644
--- a/include/debug_uart.h
+++ b/include/debug_uart.h
@@ -64,46 +64,46 @@ void debug_uart_init(void);
*
* @ch: Character to output
*/
-asmlinkage void printch(int ch);
+void printch(int ch);
/**
* printascii() - Output an ASCII string to the debug UART
*
* @str: String to output
*/
-asmlinkage void printascii(const char *str);
+void printascii(const char *str);
/**
* printhex2() - Output a 2-digit hex value
*
* @value: Value to output
*/
-asmlinkage void printhex2(uint value);
+void printhex2(uint value);
/**
* printhex4() - Output a 4-digit hex value
*
* @value: Value to output
*/
-asmlinkage void printhex4(uint value);
+void printhex4(uint value);
/**
* printhex8() - Output a 8-digit hex value
*
* @value: Value to output
*/
-asmlinkage void printhex8(uint value);
+void printhex8(uint value);
/*
* Now define some functions - this should be inserted into the serial driver
*/
#define DEBUG_UART_FUNCS \
- asmlinkage void printch(int ch) \
+ void printch(int ch) \
{ \
_debug_uart_putc(ch); \
} \
\
- asmlinkage void printascii(const char *str) \
+ void printascii(const char *str) \
{ \
while (*str) \
_debug_uart_putc(*str++); \
@@ -121,17 +121,17 @@ asmlinkage void printhex8(uint value);
printhex1(value >> (4 * digits)); \
} \
\
- asmlinkage void printhex2(uint value) \
+ void printhex2(uint value) \
{ \
printhex(value, 2); \
} \
\
- asmlinkage void printhex4(uint value) \
+ void printhex4(uint value) \
{ \
printhex(value, 4); \
} \
\
- asmlinkage void printhex8(uint value) \
+ void printhex8(uint value) \
{ \
printhex(value, 8); \
}
--
2.2.0.rc0.207.ga3a616c
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