drivers/bitbang: add support for SWD multidrop

Ignore ack received after DP_TARGETSEL write to prevent false error.

This change also fixes a bug:
Received ACK FAULT or JUNK value were incorrectly stored to queued_retval
and later used as bitbang_swd_run_queue() error return.

Use LOG_ERROR for parity mismatch.

Change-Id: I5ff1f658f221af78d8bbec8416a7a0fc64ba2550
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/6700
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

diff --git a/src/jtag/drivers/bitbang.c b/src/jtag/drivers/bitbang.c
index d202a059610f057b1a462434fe5b80eb875dc228..898d6d3df9c5d482d167348d8f6b8a8e45416023 100644 (file)
--- a/src/jtag/drivers/bitbang.c
+++ b/src/jtag/drivers/bitbang.c
@@ -492,38 +492,30 @@ static void bitbang_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay
                uint32_t data = buf_get_u32(trn_ack_data_parity_trn, 1 + 3, 32);
                int parity = buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 32, 1);
 
-               LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
+               LOG_DEBUG("%s %s read reg %X = %08"PRIx32,
                          ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
                          cmd & SWD_CMD_APNDP ? "AP" : "DP",
-                         cmd & SWD_CMD_RNW ? "read" : "write",
                          (cmd & SWD_CMD_A32) >> 1,
                          data);
 
-               switch (ack) {
-                case SWD_ACK_OK:
-                       if (parity != parity_u32(data)) {
-                               LOG_DEBUG("Wrong parity detected");
-                               queued_retval = ERROR_FAIL;
-                               return;
-                       }
-                       if (value)
-                               *value = data;
-                       if (cmd & SWD_CMD_APNDP)
-                               bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
-                       return;
-                case SWD_ACK_WAIT:
-                       LOG_DEBUG("SWD_ACK_WAIT");
+               if (ack == SWD_ACK_WAIT) {
                        swd_clear_sticky_errors();
-                       break;
-                case SWD_ACK_FAULT:
-                       LOG_DEBUG("SWD_ACK_FAULT");
-                       queued_retval = ack;
+                       continue;
+               } else if (ack != SWD_ACK_OK) {
+                       queued_retval = swd_ack_to_error_code(ack);
                        return;
-                default:
-                       LOG_DEBUG("No valid acknowledge: ack=%d", ack);
-                       queued_retval = ack;
+               }
+
+               if (parity != parity_u32(data)) {
+                       LOG_ERROR("Wrong parity detected");
+                       queued_retval = ERROR_FAIL;
                        return;
                }
+               if (value)
+                       *value = data;
+               if (cmd & SWD_CMD_APNDP)
+                       bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
+               return;
        }
 }
 
@@ -537,6 +529,9 @@ static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay
                return;
        }
 
+       /* Devices do not reply to DP_TARGETSEL write cmd, ignore received ack */
+       bool check_ack = swd_cmd_returns_ack(cmd);
+
        for (;;) {
                uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];
                buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32, value);
@@ -551,31 +546,27 @@ static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay
                bitbang_swd_exchange(false, trn_ack_data_parity_trn, 1 + 3 + 1, 32 + 1);
 
                int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
-               LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
+
+               LOG_DEBUG("%s%s %s write reg %X = %08"PRIx32,
+                         check_ack ? "" : "ack ignored ",
                          ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
                          cmd & SWD_CMD_APNDP ? "AP" : "DP",
-                         cmd & SWD_CMD_RNW ? "read" : "write",
                          (cmd & SWD_CMD_A32) >> 1,
                          buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32));
 
-               switch (ack) {
-                case SWD_ACK_OK:
-                       if (cmd & SWD_CMD_APNDP)
-                               bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
-                       return;
-                case SWD_ACK_WAIT:
-                       LOG_DEBUG("SWD_ACK_WAIT");
-                       swd_clear_sticky_errors();
-                       break;
-                case SWD_ACK_FAULT:
-                       LOG_DEBUG("SWD_ACK_FAULT");
-                       queued_retval = ack;
-                       return;
-                default:
-                       LOG_DEBUG("No valid acknowledge: ack=%d", ack);
-                       queued_retval = ack;
-                       return;
+               if (check_ack) {
+                       if (ack == SWD_ACK_WAIT) {
+                               swd_clear_sticky_errors();
+                               continue;
+                       } else if (ack != SWD_ACK_OK) {
+                               queued_retval = swd_ack_to_error_code(ack);
+                               return;
+                       }
                }
+
+               if (cmd & SWD_CMD_APNDP)
+                       bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
+               return;
        }
 }