Commit 4df24fef authored by Linus Walleij's avatar Linus Walleij Committed by Russell King
Browse files

ARM: 9005/1: debug: Select flow control for all debug UARTs 



Instead of a flow control selection mechanism specifically for
8250, make this available for all debug UARTs. If the debug
UART supports waiting for CTS to be asserted, then this code
can be activated for terminals that need it.

We keep the defaults for EBSA110, Footbridge, Gemini and RPC
so that this still works as expected for these older platforms:
they assume that flow control shall be enabled for debug
prints.

I switch the location of the check for
ifdef CONFIG_DEBUG_UART_FLOW_CONTROL from the actual debug
UART drivers: the code would get compiled-out for 8250 and
Tegra unless their custom config (or passing -DFLOW_CONTROL
in the Tegra case) was not set. Instead this is conditional
at the three places where we print debug messages. The idea
is that debug UARTs can be implemented without this ifdef
boilerplate so they look cleaner, alas the ifdef has to be
somewhere.

Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 2c50a570

arch/arm/Kconfig.debug

+11 −5
Original line number Diff line number Diff line
@@ -1546,6 +1546,17 @@ config DEBUG_SIRFSOC_UART 
	bool

	depends on ARCH_SIRF



config DEBUG_UART_FLOW_CONTROL

	bool "Enable flow control (CTS) for the debug UART"

	depends on DEBUG_LL

	default y if ARCH_EBSA110 || DEBUG_FOOTBRIDGE_COM1 || DEBUG_GEMINI || ARCH_RPC

	help

	  Some UART ports are connected to terminals that will use modem

	  control signals to indicate whether they are ready to receive text.

	  In practice this means that the terminal is asserting the special

	  control signal CTS (Clear To Send). If your debug UART supports

	  this and your debug terminal will require it, enable this option.



config DEBUG_LL_INCLUDE

	string

	default "debug/sa1100.S" if DEBUG_SA1100
@@ -1893,11 +1904,6 @@ config DEBUG_UART_8250_PALMCHIP 
	  except for having a different register layout.  Say Y here if

	  the debug UART is of this type.



config DEBUG_UART_8250_FLOW_CONTROL

	bool "Enable flow control for 8250 UART"

	depends on DEBUG_LL_UART_8250 || DEBUG_UART_8250

	default y if ARCH_EBSA110 || DEBUG_FOOTBRIDGE_COM1 || DEBUG_GEMINI || ARCH_RPC



config DEBUG_UNCOMPRESS

	bool "Enable decompressor debugging via DEBUG_LL output"

	depends on ARCH_MULTIPLATFORM || PLAT_SAMSUNG || ARM_SINGLE_ARMV7M

arch/arm/boot/compressed/debug.S

+2 −0
Original line number Diff line number Diff line
@@ -8,7 +8,9 @@ 


ENTRY(putc)

	addruart r1, r2, r3

#ifdef CONFIG_DEBUG_UART_FLOW_CONTROL

	waituartcts r3, r1

#endif

	waituarttxrdy r3, r1

	senduart r0, r1

	busyuart r3, r1

arch/arm/include/debug/8250.S

+0 −2
Original line number Diff line number Diff line
@@ -49,9 +49,7 @@ 
		.endm



		.macro	waituartcts,rd,rx

#ifdef CONFIG_DEBUG_UART_8250_FLOW_CONTROL

1001:		load	\rd, [\rx, #UART_MSR << UART_SHIFT]

		tst	\rd, #UART_MSR_CTS

		beq	1001b

#endif

		.endm

arch/arm/include/debug/tegra.S

+0 −2
Original line number Diff line number Diff line
@@ -179,14 +179,12 @@ 
		.endm



		.macro	waituartcts, rd, rx

#ifdef FLOW_CONTROL

		cmp	\rx, #0

		beq	1002f

1001:		ldrb	\rd, [\rx, #UART_MSR << UART_SHIFT]

		tst	\rd, #UART_MSR_CTS

		beq	1001b

1002:

#endif

		.endm



		.macro	waituarttxrdy,rd,rx

arch/arm/kernel/debug.S

+6 −1
Original line number Diff line number Diff line
@@ -89,12 +89,17 @@ ENTRY(printascii) 
2:		teq     r1, #'\n'

		bne	3f

		mov	r1, #'\r'

#ifdef CONFIG_DEBUG_UART_FLOW_CONTROL

		waituartcts r2, r3

#endif

		waituarttxrdy r2, r3

		senduart r1, r3

		busyuart r2, r3

		mov	r1, #'\n'

3:		waituartcts r2, r3

3:

#ifdef CONFIG_DEBUG_UART_FLOW_CONTROL

		waituartcts r2, r3

#endif

		waituarttxrdy r2, r3

		senduart r1, r3

		busyuart r2, r3

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