diff options
| -rw-r--r-- | configs/minnowmax_defconfig | 2 | ||||
| -rw-r--r-- | drivers/serial/Kconfig | 46 | ||||
| -rw-r--r-- | include/debug_uart.h | 139 |
3 files changed, 185 insertions, 2 deletions
diff --git a/configs/minnowmax_defconfig b/configs/minnowmax_defconfig index 7bc9085b32..d12428996d 100644 --- a/configs/minnowmax_defconfig +++ b/configs/minnowmax_defconfig @@ -7,7 +7,5 @@ CONFIG_DEFAULT_DEVICE_TREE="minnowmax" CONFIG_VIDEO_X86=y CONFIG_FRAMEBUFFER_SET_VESA_MODE=y CONFIG_FRAMEBUFFER_VESA_MODE_11A=y -CONFIG_DEBUG_UART_NS16550=y -CONFIG_DEBUG_UART=y CONFIG_MMCONF_BASE_ADDRESS=0xe0000000 CONFIG_HAVE_INTEL_ME=y diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index c94353ba6a..6313258eac 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -7,6 +7,52 @@ config DM_SERIAL implements serial_putc() etc. The uclass interface is defined in include/serial.h. +config DEBUG_UART + bool "Enable an early debug UART for debugging" + help + The debug UART is intended for use very early in U-Boot to debug + problems when an ICE or other debug mechanism is not available. + + To use it you should: + - Make sure your UART supports this interface + - Enable CONFIG_DEBUG_UART + - Enable the CONFIG for your UART to tell it to provide this interface + (e.g. CONFIG_DEBUG_UART_NS16550) + - Define the required settings as needed (see below) + - Call debug_uart_init() before use + - Call debug_uart_putc() to output a character + + Depending on your platform it may be possible to use this UART before + a stack is available. + + If your UART does not support this interface you can probably add + support quite easily. Remember that you cannot use driver model and + it is preferred to use no stack. + + You must not use this UART once driver model is working and the + serial drivers are up and running (done in serial_init()). Otherwise + the drivers may conflict and you will get strange output. + +config DEBUG_UART_BASE + hex "Base address of UART" + depends on DEBUG_UART + help + This is the base address of your UART for memory-mapped UARTs. + + A default should be provided by your board, but if not you will need + to use the correct value here. + +config DEBUG_UART_CLOCK + int "UART input clock" + depends on DEBUG_UART + help + The UART input clock determines the speed of the internal UART + circuitry. The baud rate is derived from this by dividing the input + clock down. + + A default should be provided by your board, but if not you will need + to use the correct value here. + config UNIPHIER_SERIAL bool "UniPhier on-chip UART support" depends on ARCH_UNIPHIER && DM_SERIAL diff --git a/include/debug_uart.h b/include/debug_uart.h new file mode 100644 index 0000000000..f56797b72f --- /dev/null +++ b/include/debug_uart.h @@ -0,0 +1,139 @@ +/* + * Early debug UART support + * + * (C) Copyright 2014 Google, Inc + * Writte by Simon Glass <sjg@chromium.org> + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#ifndef _DEBUG_UART_H +#define _DEBUG_UART_H + +#include <linux/linkage.h> + +/* + * The debug UART is intended for use very early in U-Boot to debug problems + * when an ICE or other debug mechanism is not available. + * + * To use it you should: + * - Make sure your UART supports this interface + * - Enable CONFIG_DEBUG_UART + * - Enable the CONFIG for your UART to tell it to provide this interface + * (e.g. CONFIG_DEBUG_UART_NS16550) + * - Define the required settings as needed (see below) + * - Call debug_uart_init() before use + * - Call printch() to output a character + * + * Depending on your platform it may be possible to use this UART before a + * stack is available. + * + * If your UART does not support this interface you can probably add support + * quite easily. Remember that you cannot use driver model and it is preferred + * to use no stack. + * + * You must not use this UART once driver model is working and the serial + * drivers are up and running (done in serial_init()). Otherwise the drivers + * may conflict and you will get strange output. + * + * + * To enable the debug UART in your serial driver: + * + * - #include <debug_uart.h> + * - Define debug_uart_init(), trying to avoid using the stack + * - Define _debug_uart_putc() as static inline (avoiding stack usage) + * - Immediately afterwards, add DEBUG_UART_FUNCS to define the rest of the + * functionality (printch(), etc.) + */ + +/** + * debug_uart_init() - Set up the debug UART ready for use + * + * This sets up the UART with the correct baud rate, etc. + * + * Available CONFIG is: + * + * - CONFIG_DEBUG_UART_BASE: Base address of UART + * - CONFIG_BAUDRATE: Requested baud rate + * - CONFIG_DEBUG_UART_CLOCK: Input clock for UART + */ +void debug_uart_init(void); + +/** + * printch() - Output a character to the debug UART + * + * @ch: Character to output + */ +asmlinkage void printch(int ch); + +/** + * printascii() - Output an ASCII string to the debug UART + * + * @str: String to output + */ +asmlinkage void printascii(const char *str); + +/** + * printhex2() - Output a 2-digit hex value + * + * @value: Value to output + */ +asmlinkage void printhex2(uint value); + +/** + * printhex4() - Output a 4-digit hex value + * + * @value: Value to output + */ +asmlinkage void printhex4(uint value); + +/** + * printhex8() - Output a 8-digit hex value + * + * @value: Value to output + */ +asmlinkage void printhex8(uint value); + +/* + * Now define some functions - this should be inserted into the serial driver + */ +#define DEBUG_UART_FUNCS \ + asmlinkage void printch(int ch) \ + { \ + _debug_uart_putc(ch); \ + } \ +\ + asmlinkage void printascii(const char *str) \ + { \ + while (*str) \ + _debug_uart_putc(*str++); \ + } \ +\ + static inline void printhex1(uint digit) \ + { \ + digit &= 0xf; \ + _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \ + } \ +\ + static inline void printhex(uint value, int digits) \ + { \ + while (digits-- > 0) \ + printhex1(value >> (4 * digits)); \ + } \ +\ + asmlinkage void printhex2(uint value) \ + { \ + printhex(value, 2); \ + } \ +\ + asmlinkage void printhex4(uint value) \ + { \ + printhex(value, 4); \ + } \ +\ + asmlinkage void printhex8(uint value) \ + { \ + printhex(value, 8); \ + } + +#endif |
