@@ -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
@@ -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
@@ -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
@@ -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
@@ -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
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: Linus Walleij <linus.walleij@linaro.org> --- Spreading out the ifdef CONFIG_DEBUG_UART_FLOW_CONTROL is a bit of a taste choice, if preferred I can keep it in each UART driver as well. If many UART drivers implement this it is likely better like this IMO but I can do it either way. --- arch/arm/Kconfig.debug | 16 +++++++++++----- arch/arm/boot/compressed/debug.S | 2 ++ arch/arm/include/debug/8250.S | 2 -- arch/arm/include/debug/tegra.S | 2 -- arch/arm/kernel/debug.S | 7 ++++++- 5 files changed, 19 insertions(+), 10 deletions(-)