From 4df24fef09615d8f7dd2120f5072486addfd3eb9 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 27 Aug 2020 23:28:56 +0100 Subject: [PATCH] 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: Linus Walleij Signed-off-by: Russell King --- 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(-) diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 80000a66a4e3..87912e5c2256 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -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 diff --git a/arch/arm/boot/compressed/debug.S b/arch/arm/boot/compressed/debug.S index 97f4e74692e8..fac40a717fcf 100644 --- a/arch/arm/boot/compressed/debug.S +++ b/arch/arm/boot/compressed/debug.S @@ -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 diff --git a/arch/arm/include/debug/8250.S b/arch/arm/include/debug/8250.S index 769246d87fff..e3692a37cede 100644 --- a/arch/arm/include/debug/8250.S +++ b/arch/arm/include/debug/8250.S @@ -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 diff --git a/arch/arm/include/debug/tegra.S b/arch/arm/include/debug/tegra.S index 2bca6358cdd0..98daa7f48314 100644 --- a/arch/arm/include/debug/tegra.S +++ b/arch/arm/include/debug/tegra.S @@ -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 diff --git a/arch/arm/kernel/debug.S b/arch/arm/kernel/debug.S index e7c87522c176..d92f44bdf438 100644 --- a/arch/arm/kernel/debug.S +++ b/arch/arm/kernel/debug.S @@ -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