adi_v5: search for Debug and Memory AP support

Adds dap_find_ap() function.

Change-Id: I6643025624009b12d4936de67a605da52c07be49
Signed-off-by: Evan Hunter <ehunter@broadcom.com>
Reviewed-on: http://openocd.zylin.com/909
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

diff --git a/src/target/arm_adi_v5.c b/src/target/arm_adi_v5.c
index b17fd410f353453b01519672382bf0040cec3776..1572861dc2c2157ad630d3cbcbd033eb9acaff2f 100644 (file)
--- a/src/target/arm_adi_v5.c
+++ b/src/target/arm_adi_v5.c
@@ -1221,6 +1221,60 @@ static bool is_dap_cid_ok(uint32_t cid3, uint32_t cid2, uint32_t cid1, uint32_t
                        && ((cid1 & 0x0f) == 0) && cid0 == 0x0d;
 }
 
+/*
+ * This function checks the ID for each access port to find the requested Access Port type
+ */
+int dap_find_ap(struct adiv5_dap *dap, enum ap_type type_to_find, uint8_t *ap_num_out)
+{
+       int ap;
+
+       /* Maximum AP number is 255 since the SELECT register is 8 bits */
+       for (ap = 0; ap <= 255; ap++) {
+
+               /* read the IDR register of the Access Port */
+               uint32_t id_val = 0;
+               dap_ap_select(dap, ap);
+
+               int retval = dap_queue_ap_read(dap, AP_REG_IDR, &id_val);
+               if (retval != ERROR_OK)
+                       return retval;
+
+               retval = dap_run(dap);
+
+               /* IDR bits:
+                * 31-28 : Revision
+                * 27-24 : JEDEC bank (0x4 for ARM)
+                * 23-17 : JEDEC code (0x3B for ARM)
+                * 16    : Mem-AP
+                * 15-8  : Reserved
+                *  7-0  : AP Identity (1=AHB-AP 2=APB-AP 0x10=JTAG-AP)
+                */
+
+               /* Reading register for a non-existant AP should not cause an error,
+                * but just to be sure, try to continue searching if an error does happen.
+                */
+               if ((retval == ERROR_OK) &&                  /* Register read success */
+                       ((id_val & 0x0FFF0000) == 0x04770000) && /* Jedec codes match */
+                       ((id_val & 0xFF) == type_to_find)) {     /* type matches*/
+
+                       LOG_DEBUG("Found %s at AP index: %d (IDR=0x%08X)",
+                                               (type_to_find == AP_TYPE_AHB_AP)  ? "AHB-AP"  :
+                                               (type_to_find == AP_TYPE_APB_AP)  ? "APB-AP"  :
+                                               (type_to_find == AP_TYPE_JTAG_AP) ? "JTAG-AP" : "Unknown",
+                                               ap, id_val);
+
+                       *ap_num_out = ap;
+                       return ERROR_OK;
+               }
+       }
+
+       LOG_DEBUG("No %s found",
+                               (type_to_find == AP_TYPE_AHB_AP)  ? "AHB-AP"  :
+                               (type_to_find == AP_TYPE_APB_AP)  ? "APB-AP"  :
+                               (type_to_find == AP_TYPE_JTAG_AP) ? "JTAG-AP" : "Unknown");
+       return ERROR_FAIL;
+}
+
 int dap_get_debugbase(struct adiv5_dap *dap, int ap,
                        uint32_t *out_dbgbase, uint32_t *out_apid)
 {

diff --git a/src/target/arm_adi_v5.h b/src/target/arm_adi_v5.h
index bab3292a17f3a88878e4ac09ef35d7305fedc9a9..7f1ebf5ef25775e5d157e949ee09e0ad9d3a074e 100644 (file)
--- a/src/target/arm_adi_v5.h
+++ b/src/target/arm_adi_v5.h
@@ -224,6 +224,15 @@ struct dap_ops {
        int (*run)(struct adiv5_dap *dap);
 };
 
+/*
+ * Access Port types
+ */
+enum ap_type {
+       AP_TYPE_AHB_AP  = 0x01,  /* AHB Memory-AP */
+       AP_TYPE_APB_AP  = 0x02,  /* APB Memory-AP */
+       AP_TYPE_JTAG_AP = 0x10   /* JTAG-AP - JTAG master for controlling other JTAG devices */
+};
+
 /**
  * Queue an IDCODE register read.  This is primarily useful for SWD
  * transports, where it is required as part of link initialization.
@@ -423,6 +432,11 @@ int ahbap_debugport_init(struct adiv5_dap *swjdp);
 int dap_get_debugbase(struct adiv5_dap *dap, int ap,
                        uint32_t *dbgbase, uint32_t *apid);
 
+/* Probe Access Ports to find a particular type */
+int dap_find_ap(struct adiv5_dap *dap,
+                       enum ap_type type_to_find,
+                       uint8_t *ap_num_out);
+
 /* Lookup CoreSight component */
 int dap_lookup_cs_component(struct adiv5_dap *dap, int ap,
                        uint32_t dbgbase, uint8_t type, uint32_t *addr);

diff --git a/src/target/armv7a.h b/src/target/armv7a.h
index 176de53e8563f04e00aea57062f90fea8fec263e..9d6f7c24e1ebd4c85399f6a6bf527b6d88358804 100644 (file)
--- a/src/target/armv7a.h
+++ b/src/target/armv7a.h
@@ -99,6 +99,7 @@ struct armv7a_common {
        uint32_t debug_base;
        uint8_t debug_ap;
        uint8_t memory_ap;
+       bool memory_ap_available;
        /* mdir */
        uint8_t multi_processor_system;
        uint8_t cluster_id;

diff --git a/src/target/cortex_a.c b/src/target/cortex_a.c
index cc1552d61a43c0889107cd1dc9669c4d04964f03..27b780e6720fadfdaf5f39a90074df5e94f0e2bb 100644 (file)
--- a/src/target/cortex_a.c
+++ b/src/target/cortex_a.c
@@ -70,14 +70,6 @@ static int cortex_a8_virt2phys(struct target *target,
 static int cortex_a8_read_apb_ab_memory(struct target *target,
        uint32_t address, uint32_t size, uint32_t count, uint8_t *buffer);
 
-/*
- * FIXME do topology discovery using the ROM; don't
- * assume this is an OMAP3.   Also, allow for multiple ARMv7-A
- * cores, with different AP numbering ... don't use a #define
- * for these numbers, use per-core armv7a state.
- */
-#define swjdp_memoryap 0
-#define swjdp_debugap 1
 
 /*  restore cp15_control_reg at resume */
 static int cortex_a8_restore_cp15_control_reg(struct target *target)
@@ -178,11 +170,11 @@ static int cortex_a8_init_debug_access(struct target *target)
 
        /* Unlocking the debug registers for modification
         * The debugport might be uninitialised so try twice */
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_LOCKACCESS, 0xC5ACCE55);
        if (retval != ERROR_OK) {
                /* try again */
-               retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_LOCKACCESS, 0xC5ACCE55);
                if (retval == ERROR_OK)
                        LOG_USER(
@@ -192,7 +184,7 @@ static int cortex_a8_init_debug_access(struct target *target)
                return retval;
        /* Clear Sticky Power Down status Bit in PRSR to enable access to
           the registers in the Core Power Domain */
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_PRSR, &dummy);
        if (retval != ERROR_OK)
                return retval;
@@ -225,7 +217,7 @@ static int cortex_a8_exec_opcode(struct target *target,
        /* Wait for InstrCompl bit to be set */
        long long then = timeval_ms();
        while ((dscr & DSCR_INSTR_COMP) == 0) {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
                if (retval != ERROR_OK) {
                        LOG_ERROR("Could not read DSCR register, opcode = 0x%08" PRIx32, opcode);
@@ -237,14 +229,14 @@ static int cortex_a8_exec_opcode(struct target *target,
                }
        }
 
-       retval = mem_ap_sel_write_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_ITR, opcode);
        if (retval != ERROR_OK)
                return retval;
 
        then = timeval_ms();
        do {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
                if (retval != ERROR_OK) {
                        LOG_ERROR("Could not read DSCR register");
@@ -283,7 +275,7 @@ static int cortex_a8_read_regs_through_mem(struct target *target, uint32_t addre
        if (retval != ERROR_OK)
                return retval;
 
-       retval = mem_ap_sel_read_buf_u32(swjdp, swjdp_memoryap,
+       retval = mem_ap_sel_read_buf_u32(swjdp, armv7a->memory_ap,
                        (uint8_t *)(&regfile[1]), 4*15, address);
 
        return retval;
@@ -335,7 +327,7 @@ static int cortex_a8_dap_read_coreregister_u32(struct target *target,
        /* Wait for DTRRXfull then read DTRRTX */
        long long then = timeval_ms();
        while ((dscr & DSCR_DTR_TX_FULL) == 0) {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
                if (retval != ERROR_OK)
                        return retval;
@@ -345,7 +337,7 @@ static int cortex_a8_dap_read_coreregister_u32(struct target *target,
                }
        }
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DTRTX, value);
        LOG_DEBUG("read DCC 0x%08" PRIx32, *value);
 
@@ -364,7 +356,7 @@ static int cortex_a8_dap_write_coreregister_u32(struct target *target,
        LOG_DEBUG("register %i, value 0x%08" PRIx32, regnum, value);
 
        /* Check that DCCRX is not full */
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, &dscr);
        if (retval != ERROR_OK)
                return retval;
@@ -382,7 +374,7 @@ static int cortex_a8_dap_write_coreregister_u32(struct target *target,
 
        /* Write DTRRX ... sets DSCR.DTRRXfull but exec_opcode() won't care */
        LOG_DEBUG("write DCC 0x%08" PRIx32, value);
-       retval = mem_ap_sel_write_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DTRRX, value);
        if (retval != ERROR_OK)
                return retval;
@@ -440,7 +432,7 @@ static int cortex_a8_dap_write_memap_register_u32(struct target *target,
        struct armv7a_common *armv7a = target_to_armv7a(target);
        struct adiv5_dap *swjdp = armv7a->arm.dap;
 
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap, address, value);
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap, address, value);
 
        return retval;
 }
@@ -465,7 +457,7 @@ static int cortex_a8_write_dcc(struct cortex_a8_common *a8, uint32_t data)
 {
        LOG_DEBUG("write DCC 0x%08" PRIx32, data);
        return mem_ap_sel_write_u32(a8->armv7a_common.arm.dap,
-                       swjdp_debugap, a8->armv7a_common.debug_base + CPUDBG_DTRRX, data);
+               a8->armv7a_common.debug_ap, a8->armv7a_common.debug_base + CPUDBG_DTRRX, data);
 }
 
 static int cortex_a8_read_dcc(struct cortex_a8_common *a8, uint32_t *data,
@@ -481,7 +473,7 @@ static int cortex_a8_read_dcc(struct cortex_a8_common *a8, uint32_t *data,
        /* Wait for DTRRXfull */
        long long then = timeval_ms();
        while ((dscr & DSCR_DTR_TX_FULL) == 0) {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, a8->armv7a_common.debug_ap,
                                a8->armv7a_common.debug_base + CPUDBG_DSCR,
                                &dscr);
                if (retval != ERROR_OK)
@@ -492,7 +484,7 @@ static int cortex_a8_read_dcc(struct cortex_a8_common *a8, uint32_t *data,
                }
        }
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, a8->armv7a_common.debug_ap,
                        a8->armv7a_common.debug_base + CPUDBG_DTRTX, data);
        if (retval != ERROR_OK)
                return retval;
@@ -514,7 +506,7 @@ static int cortex_a8_dpm_prepare(struct arm_dpm *dpm)
        /* set up invariant:  INSTR_COMP is set after ever DPM operation */
        long long then = timeval_ms();
        for (;; ) {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, a8->armv7a_common.debug_ap,
                                a8->armv7a_common.debug_base + CPUDBG_DSCR,
                                &dscr);
                if (retval != ERROR_OK)
@@ -802,7 +794,7 @@ static int cortex_a8_poll(struct target *target)
                target_call_event_callbacks(target, TARGET_EVENT_HALTED);
                return retval;
        }
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, &dscr);
        if (retval != ERROR_OK)
                return retval;
@@ -864,7 +856,7 @@ static int cortex_a8_halt(struct target *target)
         * Tell the core to be halted by writing DRCR with 0x1
         * and then wait for the core to be halted.
         */
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DRCR, DRCR_HALT);
        if (retval != ERROR_OK)
                return retval;
@@ -872,19 +864,19 @@ static int cortex_a8_halt(struct target *target)
        /*
         * enter halting debug mode
         */
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, &dscr);
        if (retval != ERROR_OK)
                return retval;
 
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, dscr | DSCR_HALT_DBG_MODE);
        if (retval != ERROR_OK)
                return retval;
 
        long long then = timeval_ms();
        for (;; ) {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
                if (retval != ERROR_OK)
                        return retval;
@@ -1010,7 +1002,7 @@ static int cortex_a8_internal_restart(struct target *target)
         * disable IRQs by default, with optional override...
         */
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, &dscr);
        if (retval != ERROR_OK)
                return retval;
@@ -1018,12 +1010,12 @@ static int cortex_a8_internal_restart(struct target *target)
        if ((dscr & DSCR_INSTR_COMP) == 0)
                LOG_ERROR("DSCR InstrCompl must be set before leaving debug!");
 
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, dscr & ~DSCR_ITR_EN);
        if (retval != ERROR_OK)
                return retval;
 
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DRCR, DRCR_RESTART |
                        DRCR_CLEAR_EXCEPTIONS);
        if (retval != ERROR_OK)
@@ -1031,7 +1023,7 @@ static int cortex_a8_internal_restart(struct target *target)
 
        long long then = timeval_ms();
        for (;; ) {
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
                if (retval != ERROR_OK)
                        return retval;
@@ -1123,7 +1115,7 @@ static int cortex_a8_debug_entry(struct target *target)
        LOG_DEBUG("dscr = 0x%08" PRIx32, cortex_a8->cpudbg_dscr);
 
        /* REVISIT surely we should not re-read DSCR !! */
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, &dscr);
        if (retval != ERROR_OK)
                return retval;
@@ -1135,7 +1127,7 @@ static int cortex_a8_debug_entry(struct target *target)
 
        /* Enable the ITR execution once we are in debug mode */
        dscr |= DSCR_ITR_EN;
-       retval = mem_ap_sel_write_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_write_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DSCR, dscr);
        if (retval != ERROR_OK)
                return retval;
@@ -1147,7 +1139,7 @@ static int cortex_a8_debug_entry(struct target *target)
        if (target->debug_reason == DBG_REASON_WATCHPOINT) {
                uint32_t wfar;
 
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_WFAR,
                                &wfar);
                if (retval != ERROR_OK)
@@ -2107,21 +2099,21 @@ static int cortex_a8_read_phys_memory(struct target *target,
 
        if (count && buffer) {
 
-               if (apsel == swjdp_memoryap) {
+               if (armv7a->memory_ap_available && (apsel == armv7a->memory_ap)) {
 
                        /* read memory through AHB-AP */
 
                        switch (size) {
                                case 4:
-                                       retval = mem_ap_sel_read_buf_u32(swjdp, swjdp_memoryap,
+                                       retval = mem_ap_sel_read_buf_u32(swjdp, armv7a->memory_ap,
                                                buffer, 4 * count, address);
                                        break;
                                case 2:
-                                       retval = mem_ap_sel_read_buf_u16(swjdp, swjdp_memoryap,
+                                       retval = mem_ap_sel_read_buf_u16(swjdp, armv7a->memory_ap,
                                                buffer, 2 * count, address);
                                        break;
                                case 1:
-                                       retval = mem_ap_sel_read_buf_u8(swjdp, swjdp_memoryap,
+                                       retval = mem_ap_sel_read_buf_u8(swjdp, armv7a->memory_ap,
                                                buffer, count, address);
                                        break;
                        }
@@ -2151,7 +2143,7 @@ static int cortex_a8_read_memory(struct target *target, uint32_t address,
        /* cortex_a8 handles unaligned memory access */
        LOG_DEBUG("Reading memory at address 0x%x; size %d; count %d", address,
                size, count);
-       if (apsel == swjdp_memoryap) {
+       if (armv7a->memory_ap_available && (apsel == armv7a->memory_ap)) {
                retval = cortex_a8_mmu(target, &enabled);
                if (retval != ERROR_OK)
                        return retval;
@@ -2195,21 +2187,21 @@ static int cortex_a8_write_phys_memory(struct target *target,
 
        if (count && buffer) {
 
-               if (apsel == swjdp_memoryap) {
+               if (armv7a->memory_ap_available && (apsel == armv7a->memory_ap)) {
 
                        /* write memory through AHB-AP */
 
                        switch (size) {
                                case 4:
-                                       retval = mem_ap_sel_write_buf_u32(swjdp, swjdp_memoryap,
+                                       retval = mem_ap_sel_write_buf_u32(swjdp, armv7a->memory_ap,
                                                buffer, 4 * count, address);
                                        break;
                                case 2:
-                                       retval = mem_ap_sel_write_buf_u16(swjdp, swjdp_memoryap,
+                                       retval = mem_ap_sel_write_buf_u16(swjdp, armv7a->memory_ap,
                                                buffer, 2 * count, address);
                                        break;
                                case 1:
-                                       retval = mem_ap_sel_write_buf_u8(swjdp, swjdp_memoryap,
+                                       retval = mem_ap_sel_write_buf_u8(swjdp, armv7a->memory_ap,
                                                buffer, count, address);
                                        break;
                        }
@@ -2294,7 +2286,7 @@ static int cortex_a8_write_memory(struct target *target, uint32_t address,
        /* cortex_a8 handles unaligned memory access */
        LOG_DEBUG("Reading memory at address 0x%x; size %d; count %d", address,
                size, count);
-       if (apsel == swjdp_memoryap) {
+       if (armv7a->memory_ap_available && (apsel == armv7a->memory_ap)) {
 
                LOG_DEBUG("Writing memory to address 0x%x; size %d; count %d", address, size,
                        count);
@@ -2349,16 +2341,16 @@ static int cortex_a8_handle_target_request(void *priv)
        if (target->state == TARGET_RUNNING) {
                uint32_t request;
                uint32_t dscr;
-               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
 
                /* check if we have data */
                while ((dscr & DSCR_DTR_TX_FULL) && (retval == ERROR_OK)) {
-                       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+                       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                        armv7a->debug_base + CPUDBG_DTRTX, &request);
                        if (retval == ERROR_OK) {
                                target_request(target, request);
-                               retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+                               retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                                                armv7a->debug_base + CPUDBG_DSCR, &dscr);
                        }
                }
@@ -2387,6 +2379,23 @@ static int cortex_a8_examine_first(struct target *target)
        if (retval != ERROR_OK)
                return retval;
 
+       /* Search for the APB-AB - it is needed for access to debug registers */
+       retval = dap_find_ap(swjdp, AP_TYPE_APB_AP, &armv7a->debug_ap);
+       if (retval != ERROR_OK) {
+               LOG_ERROR("Could not find APB-AP for debug access");
+               return retval;
+       }
+       /* Search for the AHB-AB */
+       retval = dap_find_ap(swjdp, AP_TYPE_AHB_AP, &armv7a->memory_ap);
+       if (retval != ERROR_OK) {
+               /* AHB-AP not found - use APB-AP */
+               LOG_DEBUG("Could not find AHB-AP - using APB-AP for memory access");
+               armv7a->memory_ap_available = false;
+       } else {
+               armv7a->memory_ap_available = true;
+       }
+
+
        if (!target->dbgbase_set) {
                uint32_t dbgbase;
                /* Get ROM Table base */
@@ -2402,33 +2411,33 @@ static int cortex_a8_examine_first(struct target *target)
        } else
                armv7a->debug_base = target->dbgbase;
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_CPUID, &cpuid);
        if (retval != ERROR_OK)
                return retval;
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_CPUID, &cpuid);
        if (retval != ERROR_OK) {
                LOG_DEBUG("Examine %s failed", "CPUID");
                return retval;
        }
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_CTYPR, &ctypr);
        if (retval != ERROR_OK) {
                LOG_DEBUG("Examine %s failed", "CTYPR");
                return retval;
        }
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_TTYPR, &ttypr);
        if (retval != ERROR_OK) {
                LOG_DEBUG("Examine %s failed", "TTYPR");
                return retval;
        }
 
-       retval = mem_ap_sel_read_atomic_u32(swjdp, swjdp_debugap,
+       retval = mem_ap_sel_read_atomic_u32(swjdp, armv7a->debug_ap,
                        armv7a->debug_base + CPUDBG_DIDR, &didr);
        if (retval != ERROR_OK) {
                LOG_DEBUG("Examine %s failed", "DIDR");
@@ -2571,14 +2580,14 @@ static int cortex_a8_virt2phys(struct target *target,
        struct armv7a_common *armv7a = target_to_armv7a(target);
        struct adiv5_dap *swjdp = armv7a->arm.dap;
        uint8_t apsel = swjdp->apsel;
-       if (apsel == swjdp_memoryap) {
+       if (armv7a->memory_ap_available && (apsel == armv7a->memory_ap)) {
                uint32_t ret;
                retval = armv7a_mmu_translate_va(target,
                                virt, &ret);
                if (retval != ERROR_OK)
                        goto done;
                *phys = ret;
-       } else {/*  use this method if swjdp_memoryap not selected
+       } else {/*  use this method if armv7a->memory_ap not selected
                 *  mmu must be enable in order to get a correct translation */
                retval = cortex_a8_mmu_modify(target, 1);
                if (retval != ERROR_OK)