1 files changed, 149 insertions, 0 deletions
diff --git a/include/semihosting.h b/include/semihosting.h
new file mode 100644
index 0000000000..f1f73464e4
--- /dev/null
+++ b/include/semihosting.h
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2022 Sean Anderson <sean.anderson@seco.com>
+ */
+
+#ifndef _SEMIHOSTING_H
+#define _SEMIHOSTING_H
+
+/*
+ * These are the encoded instructions used to indicate a semihosting trap. They
+ * are named like SMH_ISA_INSN, where ISA is the instruction set (e.g.
+ * AArch64), and INSN is the mneumonic for the instruction.
+ */
+#define SMH_A64_HLT 0xD45E0000
+#define SMH_A32_SVC 0xEF123456
+#define SMH_A32_HLT 0xE10F0070
+#define SMH_T32_SVC 0xDFAB
+#define SMH_T32_HLT 0xBABC
+
+#if CONFIG_IS_ENABLED(SEMIHOSTING_FALLBACK)
+/**
+ * semihosting_enabled() - Determine whether semihosting is supported
+ *
+ * Semihosting-based drivers should call this function before making other
+ * semihosting calls.
+ *
+ * Return: %true if a debugger is attached which supports semihosting, %false
+ *         otherwise
+ */
+bool semihosting_enabled(void);
+
+/**
+ * disable_semihosting() - Cause semihosting_enabled() to return false
+ *
+ * If U-Boot ever receives an unhandled exception caused by a semihosting trap,
+ * the trap handler should call this function.
+ */
+void disable_semihosting(void);
+#else
+static inline bool semihosting_enabled(void)
+{
+	return CONFIG_IS_ENABLED(SEMIHOSTING);
+}
+
+static inline void disable_semihosting(void)
+{
+}
+#endif
+
+/**
+ * enum smh_open_mode - Numeric file modes for use with smh_open()
+ * MODE_READ: 'r'
+ * MODE_BINARY: 'b'
+ * MODE_PLUS: '+'
+ * MODE_WRITE: 'w'
+ * MODE_APPEND: 'a'
+ *
+ * These modes represent the mode string used by fopen(3) in a form which can
+ * be passed to smh_open(). These do NOT correspond directly to %O_RDONLY,
+ * %O_CREAT, etc; see fopen(3) for details. In particular, @MODE_PLUS
+ * effectively results in adding %O_RDWR, and @MODE_WRITE will add %O_TRUNC.
+ * For compatibility, @MODE_BINARY should be added when opening non-text files
+ * (such as images).
+ */
+enum smh_open_mode {
+	MODE_READ	= 0x0,
+	MODE_BINARY	= 0x1,
+	MODE_PLUS	= 0x2,
+	MODE_WRITE	= 0x4,
+	MODE_APPEND	= 0x8,
+};
+
+/**
+ * smh_open() - Open a file on the host
+ * @fname: The name of the file to open
+ * @mode: The mode to use when opening the file
+ *
+ * Return: Either a file descriptor or a negative error on failure
+ */
+long smh_open(const char *fname, enum smh_open_mode mode);
+
+/**
+ * smh_read() - Read data from a file
+ * @fd: A file descriptor returned from smh_open()
+ * @memp: Pointer to a buffer of memory of at least @len bytes
+ * @len: The number of bytes to read
+ *
+ * Return:
+ * * The number of bytes read on success, with 0 indicating %EOF
+ * * A negative error on failure
+ */
+long smh_read(long fd, void *memp, size_t len);
+
+/**
+ * smh_write() - Write data to a file
+ * @fd: A file descriptor returned from smh_open()
+ * @memp: Pointer to a buffer of memory of at least @len bytes
+ * @len: The number of bytes to read
+ * @written: Pointer which will be updated with the actual bytes written
+ *
+ * Return: 0 on success or negative error on failure
+ */
+long smh_write(long fd, const void *memp, size_t len, ulong *written);
+
+/**
+ * smh_close() - Close an open file
+ * @fd: A file descriptor returned from smh_open()
+ *
+ * Return: 0 on success or negative error on failure
+ */
+long smh_close(long fd);
+
+/**
+ * smh_flen() - Get the length of a file
+ * @fd: A file descriptor returned from smh_open()
+ *
+ * Return: The length of the file, in bytes, or a negative error on failure
+ */
+long smh_flen(long fd);
+
+/**
+ * smh_seek() - Seek to a position in a file
+ * @fd: A file descriptor returned from smh_open()
+ * @pos: The offset (in bytes) to seek to
+ *
+ * Return: 0 on success or negative error on failure
+ */
+long smh_seek(long fd, long pos);
+
+/**
+ * smh_getc() - Read a character from stdin
+ *
+ * Return: The character read, or a negative error on failure
+ */
+int smh_getc(void);
+
+/**
+ * smh_putc() - Print a character on stdout
+ * @ch: The character to print
+ */
+void smh_putc(char ch);
+
+/**
+ * smh_write0() - Print a nul-terminated string on stdout
+ * @s: The string to print
+ */
+void smh_puts(const char *s);
+
+#endif /* _SEMIHOSTING_H */