Re: [PATCH] ARM: debug: add stm32 low-level debug support

From: Neil Armstrong
Date: Mon Dec 11 2017 - 04:28:22 EST


On 04/12/2017 14:32, Ludovic Barre wrote:
> From: Ludovic Barre <ludovic.barre@xxxxxx>
>
> This adds low-level debug support on USART1 for STM32F4
> and STM32F7. Compiled via 'CONFIG_DEBUG_LL' and 'CONFIG_EARLY_PRINTK'.
> Enabled via 'earlyprintk' in bootargs.
>
> Signed-off-by: Gerald Baeza <gerald.baeza@xxxxxx>

Hi Ludovic,

Please also add your sign-off here.

Neil

> ---
> arch/arm/Kconfig.debug | 25 +++++++++++++++++++++++++
> arch/arm/include/debug/stm32.S | 41 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 66 insertions(+)
> create mode 100644 arch/arm/include/debug/stm32.S
>
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index 17685e1..9469c58 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -1140,6 +1140,26 @@ choice
>
> If unsure, say N.
>
> + config STM32F4_DEBUG_UART
> + bool "Use STM32F4 UART for low-level debug"
> + depends on ARCH_STM32
> + select DEBUG_STM32_UART
> + help
> + Say Y here if you want kernel low-level debugging support
> + on STM32 based platforms.
> +
> + If unsure, say N.
> +
> + config STM32F7_DEBUG_UART
> + bool "Use STM32F7 UART for low-level debug"
> + depends on ARCH_STM32
> + select DEBUG_STM32_UART
> + help
> + Say Y here if you want kernel low-level debugging support
> + on STM32 based platforms.
> +
> + If unsure, say N.
> +
> config TEGRA_DEBUG_UART_AUTO_ODMDATA
> bool "Kernel low-level debugging messages via Tegra UART via ODMDATA"
> depends on ARCH_TEGRA
> @@ -1424,6 +1444,10 @@ config DEBUG_STI_UART
> bool
> depends on ARCH_STI
>
> +config DEBUG_STM32_UART
> + bool
> + depends on ARCH_STM32
> +
> config DEBUG_SIRFSOC_UART
> bool
> depends on ARCH_SIRF
> @@ -1472,6 +1496,7 @@ config DEBUG_LL_INCLUDE
> default "debug/s5pv210.S" if DEBUG_S5PV210_UART
> default "debug/sirf.S" if DEBUG_SIRFSOC_UART
> default "debug/sti.S" if DEBUG_STI_UART
> + default "debug/stm32.S" if DEBUG_STM32_UART
> default "debug/tegra.S" if DEBUG_TEGRA_UART
> default "debug/ux500.S" if DEBUG_UX500_UART
> default "debug/vexpress.S" if DEBUG_VEXPRESS_UART0_DETECT
> diff --git a/arch/arm/include/debug/stm32.S b/arch/arm/include/debug/stm32.S
> new file mode 100644
> index 0000000..4015257
> --- /dev/null
> +++ b/arch/arm/include/debug/stm32.S
> @@ -0,0 +1,41 @@
> +/*
> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
> + * Author: Gerald Baeza <gerald_baeza@xxxxxx>
> + * License terms: GNU General Public License (GPL), version 2
> + */
> +
> +#define STM32_UART_BASE 0x40011000 /* USART1 */
> +
> +#ifdef CONFIG_STM32F4_DEBUG_UART
> +#define STM32_USART_SR_OFF 0x00
> +#define STM32_USART_TDR_OFF 0x04
> +#endif
> +
> +#ifdef CONFIG_STM32F7_DEBUG_UART
> +#define STM32_USART_SR_OFF 0x1C
> +#define STM32_USART_TDR_OFF 0x28
> +#endif
> +
> +#define STM32_USART_TC (1 << 6) /* Tx complete */
> +#define STM32_USART_TXE (1 << 7) /* Tx data reg empty */
> +
> + .macro addruart, rp, rv, tmp
> + ldr \rp, =STM32_UART_BASE @ physical base
> + ldr \rv, =STM32_UART_BASE @ virt base /* NoMMU */
> + .endm
> +
> + .macro senduart,rd,rx
> + strb \rd, [\rx, #STM32_USART_TDR_OFF]
> + .endm
> +
> + .macro waituart,rd,rx
> +1001: ldr \rd, [\rx, #(STM32_USART_SR_OFF)] @ Read Status Register
> + tst \rd, #STM32_USART_TXE @ TXE = 1 = tx empty
> + beq 1001b
> + .endm
> +
> + .macro busyuart,rd,rx
> +1001: ldr \rd, [\rx, #(STM32_USART_SR_OFF)] @ Read Status Register
> + tst \rd, #STM32_USART_TC @ TC = 1 = tx complete
> + beq 1001b
> + .endm
>