lib: Add common semihosting library
We factor out the arch-independent parts of the ARM semihosting
implementation as a common library so that it can be shared
with RISC-V.
Signed-off-by: Kautuk Consul <kconsul@ventanamicro.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/lib/semihosting.c b/lib/semihosting.c
new file mode 100644
index 0000000..831774e
--- /dev/null
+++ b/lib/semihosting.c
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022 Sean Anderson <sean.anderson@seco.com>
+ * Copyright 2014 Broadcom Corporation
+ */
+
+#include <common.h>
+#include <log.h>
+#include <semihosting.h>
+
+#define SYSOPEN 0x01
+#define SYSCLOSE 0x02
+#define SYSWRITEC 0x03
+#define SYSWRITE0 0x04
+#define SYSWRITE 0x05
+#define SYSREAD 0x06
+#define SYSREADC 0x07
+#define SYSISERROR 0x08
+#define SYSSEEK 0x0A
+#define SYSFLEN 0x0C
+#define SYSERRNO 0x13
+
+#if CONFIG_IS_ENABLED(SEMIHOSTING_FALLBACK)
+static bool _semihosting_enabled = true;
+static bool try_semihosting = true;
+
+bool semihosting_enabled(void)
+{
+ if (try_semihosting) {
+ smh_trap(SYSERRNO, NULL);
+ try_semihosting = false;
+ }
+
+ return _semihosting_enabled;
+}
+
+void disable_semihosting(void)
+{
+ _semihosting_enabled = false;
+}
+#endif
+
+/**
+ * smh_errno() - Read the host's errno
+ *
+ * This gets the value of the host's errno and negates it. The host's errno may
+ * or may not be set, so only call this function if a previous semihosting call
+ * has failed.
+ *
+ * Return: a negative error value
+ */
+static int smh_errno(void)
+{
+ long ret = smh_trap(SYSERRNO, NULL);
+
+ if (ret > 0 && ret < INT_MAX)
+ return -ret;
+ return -EIO;
+}
+
+long smh_open(const char *fname, enum smh_open_mode mode)
+{
+ long fd;
+ struct smh_open_s {
+ const char *fname;
+ unsigned long mode;
+ size_t len;
+ } open;
+
+ debug("%s: file \'%s\', mode \'%u\'\n", __func__, fname, mode);
+
+ open.fname = fname;
+ open.len = strlen(fname);
+ open.mode = mode;
+
+ /* Open the file on the host */
+ fd = smh_trap(SYSOPEN, &open);
+ if (fd == -1)
+ return smh_errno();
+ return fd;
+}
+
+/**
+ * struct smg_rdwr_s - Arguments for read and write
+ * @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 or write
+ */
+struct smh_rdwr_s {
+ long fd;
+ void *memp;
+ size_t len;
+};
+
+long smh_read(long fd, void *memp, size_t len)
+{
+ long ret;
+ struct smh_rdwr_s read;
+
+ debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
+
+ read.fd = fd;
+ read.memp = memp;
+ read.len = len;
+
+ ret = smh_trap(SYSREAD, &read);
+ if (ret < 0)
+ return smh_errno();
+ return len - ret;
+}
+
+long smh_write(long fd, const void *memp, size_t len, ulong *written)
+{
+ long ret;
+ struct smh_rdwr_s write;
+
+ debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
+
+ write.fd = fd;
+ write.memp = (void *)memp;
+ write.len = len;
+
+ ret = smh_trap(SYSWRITE, &write);
+ *written = len - ret;
+ if (ret)
+ return smh_errno();
+ return 0;
+}
+
+long smh_close(long fd)
+{
+ long ret;
+
+ debug("%s: fd %ld\n", __func__, fd);
+
+ ret = smh_trap(SYSCLOSE, &fd);
+ if (ret == -1)
+ return smh_errno();
+ return 0;
+}
+
+long smh_flen(long fd)
+{
+ long ret;
+
+ debug("%s: fd %ld\n", __func__, fd);
+
+ ret = smh_trap(SYSFLEN, &fd);
+ if (ret == -1)
+ return smh_errno();
+ return ret;
+}
+
+long smh_seek(long fd, long pos)
+{
+ long ret;
+ struct smh_seek_s {
+ long fd;
+ long pos;
+ } seek;
+
+ debug("%s: fd %ld pos %ld\n", __func__, fd, pos);
+
+ seek.fd = fd;
+ seek.pos = pos;
+
+ ret = smh_trap(SYSSEEK, &seek);
+ if (ret)
+ return smh_errno();
+ return 0;
+}
+
+int smh_getc(void)
+{
+ return smh_trap(SYSREADC, NULL);
+}
+
+void smh_putc(char ch)
+{
+ smh_trap(SYSWRITEC, &ch);
+}
+
+void smh_puts(const char *s)
+{
+ smh_trap(SYSWRITE0, (char *)s);
+}