[PATCH 2/8] semihosting: Add support for writing to a file

[Sughosh Ganu]

Add a function to enable writing to a file. Currently, support is
added for writing to a binary file. This would be used for
implementing the firmware update functionality for the qemu arm64
platform.

Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
---
 arch/arm/lib/semihosting.c | 41 ++++++++++++++++++++++++++++++++++++--
 include/semihosting.h      |  1 +
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/arch/arm/lib/semihosting.c b/arch/arm/lib/semihosting.c
index 3aeda1303a..08181132d1 100644
--- a/arch/arm/lib/semihosting.c
+++ b/arch/arm/lib/semihosting.c
@@ -17,11 +17,18 @@
 
 #define SYSOPEN		0x01
 #define SYSCLOSE	0x02
+#define SYSWRITE	0x5
 #define SYSREAD		0x06
 #define SYSFLEN		0x0C
 
-#define MODE_READ	0x0
-#define MODE_READBIN	0x1
+#define MODE_READ		0x0
+#define MODE_READBIN		0x1
+#define MODE_READPLUS		0x2
+#define MODE_READPLUSBIN	0x3
+#define MODE_WRITE		0x4
+#define MODE_WRITEBIN		0x5
+#define MODE_WRITEPLUS		0x6
+#define MODE_WRITEPLUSBIN	0x7
 
 /*
  * Call the handler
@@ -61,6 +68,8 @@ long smh_open(const char *fname, char *modestr)
 		mode = MODE_READ;
 	} else if (!(strcmp(modestr, "rb"))) {
 		mode = MODE_READBIN;
+	} else if (!strcmp(modestr, "w+b")) {
+		mode = MODE_WRITEPLUSBIN;
 	} else {
 		printf("%s: ERROR mode \'%s\' not supported\n", __func__,
 		       modestr);
@@ -114,6 +123,34 @@ long smh_read(long fd, void *memp, size_t len)
 	return 0;
 }
 
+/*
+ * Write 'len' bytes into the file referenced by the fd. Returns 0 on success, else
+ * a negavite value for failure
+ */
+long smh_write(long fd, void *memp, size_t len)
+{
+	long ret;
+	struct smh_write_s {
+		long fd;
+		void *memp;
+		size_t len;
+	} write;
+
+	debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
+
+	write.fd = fd;
+	write.memp = memp;
+	write.len = len;
+
+	ret = smh_trap(SYSWRITE, &write);
+
+	if (ret > 0)
+		printf("%s: ERROR ret %ld, fd %ld, len %zu, memp %p\n",
+		       __func__, ret, fd, len, memp);
+
+	return ret == 0 ? 0 : -1;
+}
+
 /*
  * Close the file using the file descriptor
  */
diff --git a/include/semihosting.h b/include/semihosting.h
index f1bf419275..fa5cecddf2 100644
--- a/include/semihosting.h
+++ b/include/semihosting.h
@@ -8,6 +8,7 @@
 
 long smh_open(const char *fname, char *modestr);
 long smh_read(long fd, void *memp, size_t len);
+long smh_write(long fd, void *memp, size_t len);
 long smh_close(long fd);
 
 #endif /* _SEMIHOSTING_H_ */
-- 
2.17.1