remote_bitbang: add use_remote_sleep option to send delays to remote

If the remote_bitbang host does not execute requests immediately,
delays performed inside OpenOCD can be lost. This option allows
the delays to be sent to the remote host so that they can be
queued and executed in order.

Signed-off-by: Jeremy Herbert <jeremy.006@gmail.com>
Signed-off-by: David Ryskalczyk <david.rysk@gmail.com>
Change-Id: Ie1b09e09ea132dd528139618e4305154819cbc9e
Reviewed-on: https://review.openocd.org/c/openocd/+/7472
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/jtag/drivers/bitbang.c

@@ -278,6 +278,15 @@ static int bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer,
 	return ERROR_OK;
 }
 
+static void bitbang_sleep(unsigned int microseconds)
+{
+	if (bitbang_interface->sleep) {
+		bitbang_interface->sleep(microseconds);
+	} else {
+		jtag_sleep(microseconds);
+	}
+}
+
 int bitbang_execute_queue(void)
 {
 	struct jtag_command *cmd = jtag_command_queue;	/* currently processed command */
@@ -351,7 +360,7 @@ int bitbang_execute_queue(void)
 				break;
 			case JTAG_SLEEP:
 				LOG_DEBUG_IO("sleep %" PRIu32, cmd->cmd.sleep->us);
-				jtag_sleep(cmd->cmd.sleep->us);
+				bitbang_sleep(cmd->cmd.sleep->us);
 				break;
 			case JTAG_TMS:
 				retval = bitbang_execute_tms(cmd);

src/jtag/drivers/bitbang.h

@@ -54,6 +54,9 @@ struct bitbang_interface {
 
 	/** Set SWCLK and SWDIO to the given value. */
 	int (*swd_write)(int swclk, int swdio);
+
+	/** Sleep for some number of microseconds. **/
+	int (*sleep)(unsigned int microseconds);
 };
 
 extern const struct swd_driver bitbang_swd;

src/jtag/drivers/remote_bitbang.c

@@ -31,6 +31,8 @@ static int remote_bitbang_fd;
 static uint8_t remote_bitbang_send_buf[512];
 static unsigned int remote_bitbang_send_buf_used;
 
+static bool use_remote_sleep;
+
 /* Circular buffer. When start == end, the buffer is empty. */
 static char remote_bitbang_recv_buf[256];
 static unsigned int remote_bitbang_recv_buf_start;
@@ -216,6 +218,32 @@ static int remote_bitbang_reset(int trst, int srst)
 	return remote_bitbang_queue(c, FLUSH_SEND_BUF);
 }
 
+static int remote_bitbang_sleep(unsigned int microseconds)
+{
+	if (!use_remote_sleep) {
+		jtag_sleep(microseconds);
+		return ERROR_OK;
+	}
+
+	int tmp;
+	unsigned int ms = microseconds / 1000;
+	unsigned int us = microseconds % 1000;
+
+	for (unsigned int i = 0; i < ms; i++) {
+		tmp = remote_bitbang_queue('D', NO_FLUSH);
+		if (tmp != ERROR_OK)
+			return tmp;
+	}
+
+	for (unsigned int i = 0; i < us; i++) {
+		tmp = remote_bitbang_queue('d', NO_FLUSH);
+		if (tmp != ERROR_OK)
+			return tmp;
+	}
+
+	return remote_bitbang_flush();
+}
+
 static int remote_bitbang_blink(int on)
 {
 	char c = on ? 'B' : 'b';
@@ -252,6 +280,7 @@ static struct bitbang_interface remote_bitbang_bitbang = {
 	.swdio_drive = &remote_bitbang_swdio_drive,
 	.swd_write = &remote_bitbang_swd_write,
 	.blink = &remote_bitbang_blink,
+	.sleep = &remote_bitbang_sleep,
 };
 
 static int remote_bitbang_init_tcp(void)
@@ -377,6 +406,16 @@ COMMAND_HANDLER(remote_bitbang_handle_remote_bitbang_host_command)
 
 static const char * const remote_bitbang_transports[] = { "jtag", "swd", NULL };
 
+COMMAND_HANDLER(remote_bitbang_handle_remote_bitbang_use_remote_sleep_command)
+{
+	if (CMD_ARGC != 1)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	COMMAND_PARSE_ON_OFF(CMD_ARGV[0], use_remote_sleep);
+
+	return ERROR_OK;
+}
+
 static const struct command_registration remote_bitbang_subcommand_handlers[] = {
 	{
 		.name = "port",
@@ -394,7 +433,15 @@ static const struct command_registration remote_bitbang_subcommand_handlers[] =
 			"  if port is 0 or unset, this is the name of the unix socket to use.",
 		.usage = "host_name",
 	},
-	COMMAND_REGISTRATION_DONE,
+	{
+		.name = "use_remote_sleep",
+		.handler = remote_bitbang_handle_remote_bitbang_use_remote_sleep_command,
+		.mode = COMMAND_CONFIG,
+		.help = "Rather than executing sleep locally, include delays in the "
+			"instruction stream for the remote host.",
+		.usage = "(on|off)",
+	},
+	COMMAND_REGISTRATION_DONE
 };
 
 static const struct command_registration remote_bitbang_command_handlers[] = {