jlink: Add EMUCOM support

EMUCOM is a way to communicate with a J-Link device via so called
channels. A channel can either be read or written in a single
operation.

Beside the reserved channels for SEGGER, there are channels available to
implement vendor and/or device specific functionalities. For example,
EMUCOM is used on many starter and development kits from Silicon Labs to
access power measurements and various other information and settings.

Change-Id: I6094109c043b34aed4a40ceabe71f30ff896bf1d
Signed-off-by: Marc Schink <openocd-dev@marcschink.de>
Reviewed-on: http://openocd.zylin.com/3794
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

src/jtag/drivers/jlink.c

@@ -1602,6 +1602,125 @@ COMMAND_HANDLER(jlink_handle_config_command)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(jlink_handle_emucom_write_command)
+{
+	int ret;
+	size_t tmp;
+	uint32_t channel;
+	uint32_t length;
+	uint8_t *buf;
+	size_t dummy;
+
+	if (CMD_ARGC != 2)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	if (!jaylink_has_cap(caps, JAYLINK_DEV_CAP_EMUCOM)) {
+		LOG_ERROR("Device does not support EMUCOM.");
+		return ERROR_FAIL;
+	}
+
+	COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], channel);
+
+	tmp = strlen(CMD_ARGV[1]);
+
+	if (tmp % 2 != 0) {
+		LOG_ERROR("Data must be encoded as hexadecimal pairs.");
+		return ERROR_COMMAND_ARGUMENT_INVALID;
+	}
+
+	buf = malloc(tmp / 2);
+
+	if (!buf) {
+		LOG_ERROR("Failed to allocate buffer.");
+		return ERROR_FAIL;
+	}
+
+	dummy = unhexify(buf, CMD_ARGV[1], tmp / 2);
+
+	if (dummy != (tmp / 2)) {
+		LOG_ERROR("Data must be encoded as hexadecimal pairs.");
+		free(buf);
+		return ERROR_COMMAND_ARGUMENT_INVALID;
+	}
+
+	length = tmp / 2;
+	ret = jaylink_emucom_write(devh, channel, buf, &length);
+
+	free(buf);
+
+	if (ret == JAYLINK_ERR_DEV_NOT_SUPPORTED) {
+		LOG_ERROR("Channel not supported by the device.");
+		return ERROR_FAIL;
+	} else if (ret != JAYLINK_OK) {
+		LOG_ERROR("Failed to write to channel: %s.",
+			jaylink_strerror_name(ret));
+		return ERROR_FAIL;
+	}
+
+	if (length != (tmp / 2))
+		LOG_WARNING("Only %" PRIu32 " bytes written to the channel.", length);
+
+	return ERROR_OK;
+}
+
+COMMAND_HANDLER(jlink_handle_emucom_read_command)
+{
+	int ret;
+	uint32_t channel;
+	uint32_t length;
+	uint8_t *buf;
+	size_t tmp;
+
+	if (CMD_ARGC != 2)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	if (!jaylink_has_cap(caps, JAYLINK_DEV_CAP_EMUCOM)) {
+		LOG_ERROR("Device does not support EMUCOM.");
+		return ERROR_FAIL;
+	}
+
+	COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], channel);
+	COMMAND_PARSE_NUMBER(u32, CMD_ARGV[1], length);
+
+	buf = malloc(length * 3 + 1);
+
+	if (!buf) {
+		LOG_ERROR("Failed to allocate buffer.");
+		return ERROR_FAIL;
+	}
+
+	ret = jaylink_emucom_read(devh, channel, buf, &length);
+
+	if (ret == JAYLINK_ERR_DEV_NOT_SUPPORTED) {
+		LOG_ERROR("Channel is not supported by the device.");
+		free(buf);
+		return ERROR_FAIL;
+	} else if (ret == JAYLINK_ERR_DEV_NOT_AVAILABLE) {
+		LOG_ERROR("Channel is not available for the requested amount of data. "
+			"%" PRIu32 " bytes are avilable.", length);
+		free(buf);
+		return ERROR_FAIL;
+	} else if (ret != JAYLINK_OK) {
+		LOG_ERROR("Failed to read from channel: %s.",
+			jaylink_strerror_name(ret));
+		free(buf);
+		return ERROR_FAIL;
+	}
+
+	tmp = hexify((char *)buf + length, buf, length, 2 * length + 1);
+
+	if (tmp != 2 * length) {
+		LOG_ERROR("Failed to convert data into hexadecimal string.");
+		free(buf);
+		return ERROR_FAIL;
+	}
+
+	command_print(CMD_CTX, "%s", buf + length);
+	free(buf);
+
+	return ERROR_OK;
+}
+
 static const struct command_registration jlink_config_subcommand_handlers[] = {
 	{
 		.name = "usb",
@@ -1647,6 +1766,24 @@ static const struct command_registration jlink_config_subcommand_handlers[] = {
 	COMMAND_REGISTRATION_DONE
 };
 
+static const struct command_registration jlink_emucom_subcommand_handlers[] = {
+	{
+		.name = "write",
+		.handler = &jlink_handle_emucom_write_command,
+		.mode = COMMAND_EXEC,
+		.help = "write to a channel",
+		.usage = "<channel> <data>",
+	},
+	{
+		.name = "read",
+		.handler = &jlink_handle_emucom_read_command,
+		.mode = COMMAND_EXEC,
+		.help = "read from a channel",
+		.usage = "<channel> <length>"
+	},
+	COMMAND_REGISTRATION_DONE
+};
+
 static const struct command_registration jlink_subcommand_handlers[] = {
 	{
 		.name = "jtag",
@@ -1696,6 +1833,12 @@ static const struct command_registration jlink_subcommand_handlers[] = {
 			"this will show the device configuration",
 		.chain = jlink_config_subcommand_handlers,
 	},
+	{
+		.name = "emucom",
+		.mode = COMMAND_EXEC,
+		.help = "access EMUCOM channel",
+		.chain = jlink_emucom_subcommand_handlers
+	},
 	COMMAND_REGISTRATION_DONE
 };