u-boot/include/debug_uart.h

1 /* SPDX-License-Identifier: GPL-2.0+ */
13  * The debug UART is intended for use very early in U-Boot to debug problems
17  * - Make sure your UART supports this interface
18  * - Enable CONFIG_DEBUG_UART
19  * - Enable the CONFIG for your UART to tell it to provide this interface
21  * - Define the required settings as needed (see below)
22  * - Call debug_uart_init() before use
23  * - Call printch() to output a character
32  * You must not use this UART once driver model is working and the serial
34  * may conflict and you will get strange output.
37  * To enable the debug UART in your serial driver:
39  * - #include <debug_uart.h>
40  * - Define _debug_uart_init(), trying to avoid using the stack
41  * - Define _debug_uart_putc() as static inline (avoiding stack usage)
42  * - Immediately afterwards, add DEBUG_UART_FUNCS to define the rest of the
52  * debug_uart_init() - Set up the debug UART ready for use
58  *    - CONFIG_DEBUG_UART_BASE: Base address of UART
59  *    - CONFIG_BAUDRATE: Requested baud rate
60  *    - CONFIG_DEBUG_UART_CLOCK: Input clock for UART
73  * printch() - Output a character to the debug UART
75  * @ch:		Character to output
80  * printascii() - Output an ASCII string to the debug UART
82  * @str:	String to output
87  * printhex2() - Output a 2-digit hex value
89  * @value:	Value to output
94  * printhex4() - Output a 4-digit hex value
96  * @value:	Value to output
101  * printhex8() - Output a 8-digit hex value
103  * @value:	Value to output
115 		((char *)reg - (char *)com_port) * \
120 		((char *)reg - (char *)com_port) * \
125  * Now define some functions - this should be inserted into the serial driver
150 		_debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \
155 		while (digits-- > 0) \