ft2232: implement TMS sequence command

Implement the new TMS_SEQ command on FT2232 hardware.
Also, swap a bogus exit() call with a clean failure return.

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

diff --git a/src/jtag/drivers/ft2232.c b/src/jtag/drivers/ft2232.c
index 4b84fa835f51283f8bc9b249aef27fc4b1b318f8..5c6b655ce88aa68ed3064e92a8931b89ff9b089c 100644 (file)
--- a/src/jtag/drivers/ft2232.c
+++ b/src/jtag/drivers/ft2232.c
@@ -1678,6 +1678,72 @@ static int ft2232_execute_statemove(struct jtag_command *cmd)
        return retval;
 }
 
+/**
+ * Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
+ * (or SWD) state machine.
+ */
+static int ft2232_execute_tms(struct jtag_command *cmd)
+{
+       int             retval = ERROR_OK;
+       unsigned        num_bits = cmd->cmd.tms->num_bits;
+       const uint8_t   *bits = cmd->cmd.tms->bits;
+       unsigned        count;
+
+       DEBUG_JTAG_IO("TMS: %d bits", num_bits);
+
+       /* only send the maximum buffer size that FT2232C can handle */
+       count = 3 * DIV_ROUND_UP(num_bits, 4);
+       if (ft2232_buffer_size + 3*count + 1 > FT2232_BUFFER_SIZE) {
+               if (ft2232_send_and_recv(first_unsent, cmd) != ERROR_OK)
+                       retval = ERROR_JTAG_QUEUE_FAILED;
+
+               require_send = 0;
+               first_unsent = cmd;
+       }
+
+       /* Shift out in batches of at most 6 bits; there's a report of an
+        * FT2232 bug in this area, where shifting exactly 7 bits can make
+        * problems with TMS signaling for the last clock cycle:
+        *
+        *    http://developer.intra2net.com/mailarchive/html/
+        *              libftdi/2009/msg00292.html
+        *
+        * Command 0x4b is: "Clock Data to TMS/CS Pin (no Read)"
+        *
+        * Note that pathmoves in JTAG are not often seven bits, so that
+        * isn't a particularly likely situation outside of "special"
+        * signaling such as switching between JTAG and SWD modes.
+        */
+       while (num_bits) {
+               if (num_bits <= 6) {
+                       buffer_write(0x4b);
+                       buffer_write(num_bits - 1);
+                       buffer_write(*bits & 0x3f);
+                       break;
+               }
+
+               /* Yes, this is lazy ... we COULD shift out more data
+                * bits per operation, but doing it in nybbles is easy
+                */
+               buffer_write(0x4b);
+               buffer_write(3);
+               buffer_write(*bits & 0xf);
+               num_bits -= 4;
+
+               count  = (num_bits > 4) ? 4 : num_bits;
+
+               buffer_write(0x4b);
+               buffer_write(count - 1);
+               buffer_write((*bits >> 4) & 0xf);
+               num_bits -= count;
+
+               bits++;
+       }
+
+       require_send = 1;
+       return retval;
+}
+
 static int ft2232_execute_pathmove(struct jtag_command *cmd)
 {
        int     predicted_size = 0;
@@ -1830,7 +1896,6 @@ static int ft2232_execute_stableclocks(struct jtag_command *cmd)
 static int ft2232_execute_command(struct jtag_command *cmd)
 {
        int retval;
-       retval = ERROR_OK;
 
        switch (cmd->type)
        {
@@ -1841,9 +1906,13 @@ static int ft2232_execute_command(struct jtag_command *cmd)
        case JTAG_SCAN:         retval = ft2232_execute_scan(cmd); break;
        case JTAG_SLEEP:        retval = ft2232_execute_sleep(cmd); break;
        case JTAG_STABLECLOCKS: retval = ft2232_execute_stableclocks(cmd); break;
+       case JTAG_TMS:
+               retval = ft2232_execute_tms(cmd);
+               break;
        default:
                LOG_ERROR("BUG: unknown JTAG command type encountered");
-               exit(-1);
+               retval = ERROR_JTAG_QUEUE_FAILED;
+               break;
        }
        return retval;
 }
@@ -4108,6 +4177,7 @@ static const struct command_registration ft2232_command_handlers[] = {
 
 struct jtag_interface ft2232_interface = {
        .name = "ft2232",
+       .supported = DEBUG_CAP_TMS_SEQ,
        .commands = ft2232_command_handlers,
 
        .init = ft2232_init,