[PATCH] MIPS: DEBUG_LL_UART_DIVISOR is 0, use a0 instead

[Du Huanpeng]

Hi, How about this, I send this for review, if it is ok,
I will send a patch later.

I add a argument to the macro, and set a default parameter.

+.macro	debug_ll_ns16550_init divisor=DEBUG_LL_UART_DIVISOR


+	/* three forms for ``call'' the macro */
pass a register name
+	debug_ll_ns16550_init v0

pass a immediate number
+	debug_ll_ns16550_init 888

use this macro as usual before
+	debug_ll_ns16550_init

----8<-----

diff --git a/arch/mips/boards/loongson-ls1b/lowlevel.S b/arch/mips/boards/loongson-ls1b/lowlevel.S
index af6ad54e1..7120d80ef 100644
--- a/arch/mips/boards/loongson-ls1b/lowlevel.S
+++ b/arch/mips/boards/loongson-ls1b/lowlevel.S
@@ -28,8 +28,14 @@ ENTRY_FUNCTION(BOARD_PBL_START)
 
 	pbl_loongson1_uart_enable
 	pbl_loongson1_calc_prescale 115200
-	move	a0, v0
+
+	/* three forms for ``call'' the macro */
+	debug_ll_ns16550_init v0
+	debug_ll_ns16550_init 888
+	debug_ll_ns16550_init
+
 	debug_ll_ns16550_init
+
 	debug_ll_ns16550_outnl
 	debug_ll_outc '.'
 	debug_ll_ns16550_outnl
diff --git a/arch/mips/include/asm/debug_ll_ns16550.h b/arch/mips/include/asm/debug_ll_ns16550.h
index a33587a15..44f3d5976 100644
--- a/arch/mips/include/asm/debug_ll_ns16550.h
+++ b/arch/mips/include/asm/debug_ll_ns16550.h
@@ -58,17 +58,14 @@ static inline void PUTC_LL(char ch)
  * Macros for use in assembly language code
  */
 
-.macro	debug_ll_ns16550_init
+.macro	debug_ll_ns16550_init divisor=DEBUG_LL_UART_DIVISOR
 #ifdef CONFIG_DEBUG_LL
 	la	t0, DEBUG_LL_UART_ADDR
 
 	li	t1, UART_LCR_DLAB		/* DLAB on */
 	sb	t1, UART_LCR(t0)		/* Write it out */
 
-	li	t1, DEBUG_LL_UART_DIVISOR
-#if DEBUG_LL_UART_DIVISOR == 0
-	move	t1, a0
-#endif
+	add	t1, zero, \divisor
 	sb	t1, UART_DLL(t0)		/* write low order byte */
 	srl	t1, t1, 8
 	sb	t1, UART_DLM(t0)		/* write high order byte */