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drivers: ram_console: add option to link console buffer to given section

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Currently, the ram_console buffer is defined as a global var, its
address is determined during the building and may be changed when
code update. This is not a problem if the ram_console is just used
in debug purpose.

While in the heterogeneous SoCs, there can be multiple MPU Cores
and several MCU cores, it can run multiple OS/bare-metal instances
on these cores, but the UART ports may be not enough, so the
ram_console can be leveraged. To make it easy to use, it's better
make the console buffer fixed and predefined.

This patch adds a option to link the console buffer to a given
section, through the "zephyr,memory-region" device tree node, then
the address can be known from the device tree node and easy to
check from other cores running Linux/U-Boot.

To use this option, the chosen property 'zephyr,ram-console' must
be added, the following is a example:

	chosen {
		zephyr,ram-console = &ram_console;
	};

	ram_console: memory@93d00000 {
		compatible = "zephyr,memory-region";
		reg = <0x93d00000 DT_SIZE_K(4)>;
		zephyr,memory-region = "RAM_CONSOLE";
	};

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
This commit is contained in:
Hou Zhiqiang 2024-01-24 15:18:25 +08:00 • committed by David Leach
commit 1cd37f21f3
2 changed files with 40 additions and 1 deletions
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14
drivers/console/Kconfig
View file

@ -95,16 +95,30 @@ config JAILHOUSE_DEBUG_CONSOLE
Useful in board bring-up if there aren't any working serial
drivers.
# Workaround for not being able to have commas in macro arguments
DT_CHOSEN_Z_RAM_CONSOLE := zephyr,ram-console
config RAM_CONSOLE
bool "Use RAM console"
select CONSOLE_HAS_DRIVER
select RAM_CONSOLE_BUFFER_SECTION if $(dt_chosen_enabled,$(DT_CHOSEN_Z_RAM_CONSOLE))
help
Emit console messages to a RAM buffer "ram_console" which can
be examined at runtime with a debugger. Useful in board bring-up
if there aren't any working serial drivers.
config RAM_CONSOLE_BUFFER_SECTION
bool "Use dedicated section as RAM console buffer"
depends on RAM_CONSOLE && $(dt_chosen_enabled,$(DT_CHOSEN_Z_RAM_CONSOLE))
select KERNEL_DIRECT_MAP if MMU
help
Use a dedicated section as the RAM console buffer, whose address is
known before build so that the console output messages can be easily
examined by a debugger or software tool from a parallel-running OS.
config RAM_CONSOLE_BUFFER_SIZE
int "Ram Console buffer size"
default $(dt_chosen_reg_size_int,$(DT_CHOSEN_Z_RAM_CONSOLE)) if RAM_CONSOLE_BUFFER_SECTION
default 1024
depends on RAM_CONSOLE
help

27
drivers/console/ram_console.c
View file

@ -2,6 +2,7 @@
/*
* Copyright (c) 2015 Intel Corporation
* Copyright 2024 NXP
*
* SPDX-License-Identifier: Apache-2.0
*/
@ -11,11 +12,26 @@
#include <zephyr/sys/printk.h>
#include <zephyr/device.h>
#include <zephyr/init.h>
#include <zephyr/linker/devicetree_regions.h>
#ifdef CONFIG_RAM_CONSOLE_BUFFER_SECTION
#if !DT_HAS_CHOSEN(zephyr_ram_console)
#error "Lack of chosen property zephyr,ram_console!"
#elif (CONFIG_RAM_CONSOLE_BUFFER_SIZE > DT_REG_SIZE(DT_CHOSEN(zephyr_ram_console)))
#error "Custom RAM console buffer exceeds the section size!"
#endif
#define RAM_CONSOLE_BUF_ATTR \
__attribute__((__section__(LINKER_DT_NODE_REGION_NAME(DT_CHOSEN(zephyr_ram_console)))))
#else
#define RAM_CONSOLE_BUF_ATTR
#endif
extern void __printk_hook_install(int (*fn)(int));
extern void __stdout_hook_install(int (*fn)(int));
char ram_console[CONFIG_RAM_CONSOLE_BUFFER_SIZE];
char ram_console_buf[CONFIG_RAM_CONSOLE_BUFFER_SIZE] RAM_CONSOLE_BUF_ATTR;
char *ram_console;
static int pos;
static int ram_console_out(int character)
@ -28,6 +44,15 @@ static int ram_console_out(int character)
static int ram_console_init(void)
{
#ifdef CONFIG_RAM_CONSOLE_BUFFER_SECTION
mm_reg_t ram_console_va;
device_map((mm_reg_t *)&ram_console_va, DT_REG_ADDR(DT_CHOSEN(zephyr_ram_console)),
CONFIG_RAM_CONSOLE_BUFFER_SIZE, K_MEM_CACHE_NONE | K_MEM_DIRECT_MAP);
ram_console = (char *)ram_console_va,
#else
ram_console = ram_console_buf,
#endif
__printk_hook_install(ram_console_out);
__stdout_hook_install(ram_console_out);