interface: define TMS sequence command

For support of SWD we need to be able to clock out special bit
sequences over TMS or SWDIO.  Create this as a generic operation,
not yet called by anything, which is split as usual into:

 - upper level abstraction ... here, jtag_add_tms_seq();
 - midlayer implementation logic hooking that to the lowlevel code;
 - lowlevel minidriver operation ... here, interface_add_tms_seq();
 - message type for request queue, here JTAG_TMS.

This is done slightly differently than other operations: there's a flag
saying whether the interface driver supports this request.  (In fact a
flag *word* so upper layers can learn about other capabilities too ...
for example, supporting SWD operations.)

That approach (flag) lets this method *eventually* be used to eliminate
pathmove() and statemove() support from most adapter drivers, by moving
all that logic into the mid-layer and increasing uniformity between the
various drivers.  (Which will in turn reduce subtle bugginess.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/jtag/drivers/driver.c

@@ -388,6 +388,31 @@ int interface_jtag_add_tlr(void)
 	return ERROR_OK;
 }
 
+int interface_add_tms_seq(unsigned num_bits, const uint8_t *seq)
+{
+	struct jtag_command *cmd;
+
+	cmd = cmd_queue_alloc(sizeof(struct jtag_command));
+	if (cmd == NULL)
+		return ERROR_FAIL;
+
+	cmd->type = JTAG_TMS;
+	cmd->cmd.tms = cmd_queue_alloc(sizeof(*cmd->cmd.tms));
+	if (!cmd->cmd.tms)
+		return ERROR_FAIL;
+
+	/* copy the bits; our caller doesn't guarantee they'll persist */
+	cmd->cmd.tms->num_bits = num_bits;
+	cmd->cmd.tms->bits = buf_cpy(seq,
+			cmd_queue_alloc(DIV_ROUND_UP(num_bits, 8)), num_bits);
+	if (!cmd->cmd.tms->bits)
+		return ERROR_FAIL;
+
+	jtag_queue_command(cmd);
+
+	return ERROR_OK;
+}
+
 int interface_jtag_add_pathmove(int num_states, const tap_state_t *path)
 {
 	/* allocate memory for a new list member */