1 files changed, 200 insertions, 0 deletions
diff --git a/include/debug_uart.h b/include/debug_uart.h
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+++ b/include/debug_uart.h
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+/* 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(uint value);
+
+/**
+ * printhex4() - Output a 4-digit hex value
+ *
+ * @value:	Value to output
+ */
+void printhex4(uint value);
+
+/**
+ * printhex8() - Output a 8-digit hex value
+ *
+ * @value:	Value to output
+ */
+void printhex8(uint value);
+
+/**
+ * printdec() - Output a decimalism value
+ *
+ * @value:	Value to output
+ */
+void printdec(uint value);
+
+#ifdef CONFIG_DEBUG_UART_ANNOUNCE
+#define _DEBUG_UART_ANNOUNCE	printascii("<debug_uart> ");
+#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(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)); \
+	} \
+\
+	void printhex2(uint value) \
+	{ \
+		printhex(value, 2); \
+	} \
+\
+	void printhex4(uint value) \
+	{ \
+		printhex(value, 4); \
+	} \
+\
+	void printhex8(uint value) \
+	{ \
+		printhex(value, 8); \
+	} \
+\
+	void printdec(uint 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