semihosting: support fileio operation

This patch adds support for bridging semihosting to GDB's File-I/O
remote protocol extension. For the most part operations match up 1:1,
however some require a working area to complete successfully, namely
operations that devolve to read, stat, and gettimeofday.

A new command was added to enable support for fileio named `arm
semihosting_fileio`, which ensures that the default behavior remains
intact for those that prefer it.

Finally, redundant logging was removed from the target_arch_state
function; this permits ARM targets to quiesce log output when polling
for a fileio reply. This prevents filling the logs with halt/resume
messages when using semihosting fileio.

Change-Id: Ifbb864fc2373336a501cc0332675b887b552e1ee
Signed-off-by: Steven Stallion <stallion@squareup.com>
Reviewed-on: http://openocd.zylin.com/3566
Tested-by: jenkins
Reviewed-by: Steven Stallion <sstallion@gmail.com>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

1 files changed, 45 insertions, 2 deletions

diff --git a/src/target/armv4_5.c b/src/target/armv4_5.c
index 1a31d40c..624a2543 100644
--- a/src/target/armv4_5.c
+++ b/src/target/armv4_5.c
@@ -666,14 +666,19 @@ int arm_arch_state(struct target *target)
 		return ERROR_FAIL;
 	}
 
+	/* avoid filling log waiting for fileio reply */
+	if (arm->semihosting_hit_fileio)
+		return ERROR_OK;
+
 	LOG_USER("target halted in %s state due to %s, current mode: %s\n"
-		"cpsr: 0x%8.8" PRIx32 " pc: 0x%8.8" PRIx32 "%s",
+		"cpsr: 0x%8.8" PRIx32 " pc: 0x%8.8" PRIx32 "%s%s",
 		arm_state_strings[arm->core_state],
 		debug_reason_name(target),
 		arm_mode_name(arm->core_mode),
 		buf_get_u32(arm->cpsr->value, 0, 32),
 		buf_get_u32(arm->pc->value, 0, 32),
-		arm->is_semihosting ? ", semihosting" : "");
+		arm->is_semihosting ? ", semihosting" : "",
+		arm->is_semihosting_fileio ? " fileio" : "");
 
 	return ERROR_OK;
 }
@@ -1055,6 +1060,37 @@ COMMAND_HANDLER(handle_arm_semihosting_command)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(handle_arm_semihosting_fileio_command)
+{
+	struct target *target = get_current_target(CMD_CTX);
+
+	if (target == NULL) {
+		LOG_ERROR("No target selected");
+		return ERROR_FAIL;
+	}
+
+	struct arm *arm = target_to_arm(target);
+
+	if (!is_arm(arm)) {
+		command_print(CMD_CTX, "current target isn't an ARM");
+		return ERROR_FAIL;
+	}
+
+	if (!arm->is_semihosting) {
+		command_print(CMD_CTX, "semihosting is not enabled");
+		return ERROR_FAIL;
+	}
+
+	if (CMD_ARGC > 0)
+		COMMAND_PARSE_ENABLE(CMD_ARGV[0], arm->is_semihosting_fileio);
+
+	command_print(CMD_CTX, "semihosting fileio is %s",
+		arm->is_semihosting_fileio
+		? "enabled" : "disabled");
+
+	return ERROR_OK;
+}
+
 static const struct command_registration arm_exec_command_handlers[] = {
 	{
 		.name = "reg",
@@ -1097,6 +1133,13 @@ static const struct command_registration arm_exec_command_handlers[] = {
 		.usage = "['enable'|'disable']",
 		.help = "activate support for semihosting operations",
 	},
+	{
+		"semihosting_fileio",
+		.handler = handle_arm_semihosting_fileio_command,
+		.mode = COMMAND_EXEC,
+		.usage = "['enable'|'disable']",
+		.help = "activate support for semihosting fileio operations",
+	},
 
 	COMMAND_REGISTRATION_DONE
 };