mips_ejtag: remove memory protection bit before DM

[openocd.git] / src / target / mips_ejtag.c

diff --git a/src/target/mips_ejtag.c b/src/target/mips_ejtag.c
index 3726191273b78ad1aafd1e47a1f5ecf79aa3f156..85748146d0d7725aa6083981f066c7243de4ea06 100644 (file)
--- a/src/target/mips_ejtag.c
+++ b/src/target/mips_ejtag.c
@@ -28,6 +28,7 @@
 
 #include "mips32.h"
 #include "mips_ejtag.h"
+#include "mips32_dmaacc.h"
 
 void mips_ejtag_set_instr(struct mips_ejtag *ejtag_info, int new_instr)
 {
@@ -237,11 +238,41 @@ exit:
        return ctx.retval;
 }
 
+/*
+ * Disable memory protection for 0xFF20.0000–0xFF3F.FFFF
+ * It is needed by EJTAG 1.5-2.0, especially for BMIPS CPUs
+ * For example bcm7401 and others. At leas on some
+ * CPUs, DebugMode wont start if this bit is not removed.
+ */
+static int disable_dcr_mp(struct mips_ejtag *ejtag_info)
+{
+       uint32_t dcr;
+       int retval;
+
+       retval = mips32_dmaacc_read_mem(ejtag_info, EJTAG_DCR, 4, 1, &dcr);
+       if (retval != ERROR_OK)
+               goto error;
+
+       dcr &= ~EJTAG_DCR_MP;
+       retval = mips32_dmaacc_write_mem(ejtag_info, EJTAG_DCR, 4, 1, &dcr);
+       if (retval != ERROR_OK)
+               goto error;
+       return ERROR_OK;
+error:
+       LOG_ERROR("Failed to remove DCR MPbit!");
+       return retval;
+}
+
 int mips_ejtag_enter_debug(struct mips_ejtag *ejtag_info)
 {
        uint32_t ejtag_ctrl;
        mips_ejtag_set_instr(ejtag_info, EJTAG_INST_CONTROL);
 
+       if (ejtag_info->ejtag_version == EJTAG_VERSION_20) {
+               if (disable_dcr_mp(ejtag_info) != ERROR_OK)
+                       goto error;
+       }
+
        /* set debug break bit */
        ejtag_ctrl = ejtag_info->ejtag_ctrl | EJTAG_CTRL_JTAGBRK;
        mips_ejtag_drscan_32(ejtag_info, &ejtag_ctrl);
@@ -250,12 +281,13 @@ int mips_ejtag_enter_debug(struct mips_ejtag *ejtag_info)
        ejtag_ctrl = ejtag_info->ejtag_ctrl;
        mips_ejtag_drscan_32(ejtag_info, &ejtag_ctrl);
        LOG_DEBUG("ejtag_ctrl: 0x%8.8" PRIx32 "", ejtag_ctrl);
-       if ((ejtag_ctrl & EJTAG_CTRL_BRKST) == 0) {
-               LOG_ERROR("Failed to enter Debug Mode!");
-               return ERROR_FAIL;
-       }
+       if ((ejtag_ctrl & EJTAG_CTRL_BRKST) == 0)
+               goto error;
 
        return ERROR_OK;
+error:
+       LOG_ERROR("Failed to enter Debug Mode!");
+       return ERROR_FAIL;
 }
 
 int mips_ejtag_exit_debug(struct mips_ejtag *ejtag_info)