/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Early debug UART support
 *
 * (C) Copyright 2014 Google, Inc
 * Writte by Simon Glass <sjg@chromium.org>
 */

#ifndef _DEBUG_UART_H
#define _DEBUG_UART_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.)
 *
 * If your board needs additional init for the UART to work, enable
 * CONFIG_DEBUG_UART_BOARD_INIT and write a function called
 * board_debug_uart_init() to perform that init. When debug_uart_init() is
 * called, the init will happen automatically.
 */

/**
 * 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);

#ifdef CONFIG_DEBUG_UART_BOARD_INIT
void board_debug_uart_init(void);
#else
static inline void board_debug_uart_init(void)
{
}
#endif

/**
 * printch() - Output a character to the debug UART
 *
 * @ch:         Character to output
 */
void printch(int ch);

/**
 * printascii() - Output an ASCII string to the debug UART
 *
 * @str:        String to output
 */
void printascii(const char *str);

/**
 * printhex2() - Output a 2-digit hex value
 *
 * @value:      Value to output
 */
void printhex2(unsigned int value);

/**
 * printhex4() - Output a 4-digit hex value
 *
 * @value:      Value to output
 */
void printhex4(unsigned int value);

/**
 * printhex8() - Output a 8-digit hex value
 *
 * @value:      Value to output
 */
void printhex8(unsigned int value);

/**
 * printdec() - Output a decimalism value
 *
 * @value:      Value to output
 */
void printdec(unsigned int value);

#ifdef CONFIG_DEBUG_UART_ANNOUNCE
#define _DEBUG_UART_ANNOUNCE    printascii("\n<debug_uart>\n");
#else
#define _DEBUG_UART_ANNOUNCE
#endif

#define serial_dout(reg, value) \
        serial_out_shift((char *)com_port + \
                ((char *)reg - (char *)com_port) * \
                        (1 << CONFIG_DEBUG_UART_SHIFT), \
                CONFIG_DEBUG_UART_SHIFT, value)
#define serial_din(reg) \
        serial_in_shift((char *)com_port + \
                ((char *)reg - (char *)com_port) * \
                        (1 << CONFIG_DEBUG_UART_SHIFT), \
                CONFIG_DEBUG_UART_SHIFT)

/*
 * Now define some functions - this should be inserted into the serial driver
 */
#define DEBUG_UART_FUNCS \
\
        static inline void _printch(int ch) \
        { \
                if (ch == '\n') \
                        _debug_uart_putc('\r'); \
                _debug_uart_putc(ch); \
        } \
\
        void printch(int ch) \
        { \
                _printch(ch); \
        } \
\
        void printascii(const char *str) \
        { \
                while (*str) \
                        _printch(*str++); \
        } \
\
        static inline void printhex1(unsigned int digit) \
        { \
                digit &= 0xf; \
                _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \
        } \
\
        static inline void printhex(unsigned int value, int digits) \
        { \
                while (digits-- > 0) \
                        printhex1(value >> (4 * digits)); \
        } \
\
        void printhex2(unsigned int value) \
        { \
                printhex(value, 2); \
        } \
\
        void printhex4(unsigned int value) \
        { \
                printhex(value, 4); \
        } \
\
        void printhex8(unsigned int value) \
        { \
                printhex(value, 8); \
        } \
\
        void printdec(unsigned int value) \
        { \
                if (value > 10) { \
                        printdec(value / 10); \
                        value %= 10; \
                } else if (value == 10) { \
                        _debug_uart_putc('1'); \
                        value = 0; \
                } \
                _debug_uart_putc('0' + value); \
        } \
\
        void debug_uart_init(void) \
        { \
                board_debug_uart_init(); \
                _debug_uart_init(); \
                _DEBUG_UART_ANNOUNCE \
        } \

#endif