stlink_usb: Changes to make connect_under_reset work

Leaving mode before closing added
Resolved a collision with JTAG API v1 error/status
checking overwriting SWIM status bytes

Change-Id: I35444ec0e6caace3e072c60085059602f4cdf0a4
Signed-off-by: Ake Rehnman <ake.rehnman@gmail.com>
Reviewed-on: http://openocd.zylin.com/4265
Tested-by: jenkins
Reviewed-by: Philipp Klaus Krause
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

diff --git a/src/jtag/drivers/stlink_usb.c b/src/jtag/drivers/stlink_usb.c
index 3865b3b7da90bbaeff15851c141575bfcab7d426..6f720b86b3ad2bbecbf224fe216caa0886d1938c 100644 (file)
--- a/src/jtag/drivers/stlink_usb.c
+++ b/src/jtag/drivers/stlink_usb.c
@@ -425,10 +425,6 @@ static int stlink_usb_error_check(void *handle)
 
        assert(handle != NULL);
 
-       /* TODO: no error checking yet on api V1 */
-       if (h->jtag_api == STLINK_JTAG_API_V1)
-               h->databuf[0] = STLINK_DEBUG_ERR_OK;
-
        if (h->transport == HL_TRANSPORT_SWIM) {
                switch (h->databuf[0]) {
                        case STLINK_SWIM_ERR_OK:
@@ -441,6 +437,10 @@ static int stlink_usb_error_check(void *handle)
                }
        }
 
+       /* TODO: no error checking yet on api V1 */
+       if (h->jtag_api == STLINK_JTAG_API_V1)
+               h->databuf[0] = STLINK_DEBUG_ERR_OK;
+
        switch (h->databuf[0]) {
                case STLINK_DEBUG_ERR_OK:
                        return ERROR_OK;
@@ -904,23 +904,29 @@ static int stlink_usb_init_mode(void *handle, bool connect_under_reset)
                return ERROR_FAIL;
        }
 
+       /* preliminary SRST assert:
+        * We want SRST is asserted before activating debug signals (mode_enter).
+        * As the required mode has not been set, the adapter may not know what pin to use.
+        * Tested firmware STLINK v2 JTAG v29 API v2 SWIM v0 uses T_NRST pin by default
+        * Tested firmware STLINK v2 JTAG v27 API v2 SWIM v6 uses T_NRST pin by default
+        * after power on, SWIM_RST stays unchanged */
+       if (connect_under_reset && emode != STLINK_MODE_DEBUG_SWIM)
+               stlink_usb_assert_srst(handle, 0);
+               /* do not check the return status here, we will
+                  proceed and enter the desired mode below
+                  and try asserting srst again. */
+
+       res = stlink_usb_mode_enter(handle, emode);
+       if (res != ERROR_OK)
+               return res;
+
+       /* assert SRST again: a little bit late but now the adapter knows for sure what pin to use */
        if (connect_under_reset) {
-               /* if we are going to use swim we need to switch mode early */
-               if (emode == STLINK_MODE_DEBUG_SWIM) {
-                       res = stlink_usb_mode_enter(handle, emode);
-                       if (res != ERROR_OK)
-                               return res;
-               }
                res = stlink_usb_assert_srst(handle, 0);
                if (res != ERROR_OK)
                        return res;
        }
 
-       res = stlink_usb_mode_enter(handle, emode);
-
-       if (res != ERROR_OK)
-               return res;
-
        res = stlink_usb_current_mode(handle, &mode);
 
        if (res != ERROR_OK)
@@ -1949,8 +1955,43 @@ static int stlink_speed(void *handle, int khz, bool query)
 /** */
 static int stlink_usb_close(void *handle)
 {
+       int res;
+       uint8_t mode;
+       enum stlink_mode emode;
        struct stlink_usb_handle_s *h = handle;
 
+       if (h && h->fd)
+               res = stlink_usb_current_mode(handle, &mode);
+       else
+               res = ERROR_FAIL;
+       /* do not exit if return code != ERROR_OK,
+          it prevents us from closing jtag_libusb */
+
+       if (res == ERROR_OK) {
+               /* try to exit current mode */
+               switch (mode) {
+                       case STLINK_DEV_DFU_MODE:
+                               emode = STLINK_MODE_DFU;
+                               break;
+                       case STLINK_DEV_DEBUG_MODE:
+                               emode = STLINK_MODE_DEBUG_SWD;
+                               break;
+                       case STLINK_DEV_SWIM_MODE:
+                               emode = STLINK_MODE_DEBUG_SWIM;
+                               break;
+                       case STLINK_DEV_BOOTLOADER_MODE:
+                       case STLINK_DEV_MASS_MODE:
+                       default:
+                               emode = STLINK_MODE_UNKNOWN;
+                               break;
+               }
+
+               if (emode != STLINK_MODE_UNKNOWN)
+                       stlink_usb_mode_leave(handle, emode);
+                       /* do not check return code, it prevent
+                       us from closing jtag_libusb */
+       }
+
        if (h && h->fd)
                jtag_libusb_close(h->fd);