target/cortex_a: add support for watchpoint length of 1, 2 and 4 bytes

Use byte address select for 1 and 2 bytes length.
Use normal mode for 4 bytes length.

Change-Id: I28d182f25145d0635de64d0361d456f1ad96640e
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6197
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

diff --git a/src/target/cortex_a.c b/src/target/cortex_a.c
index 78daed398817b6ec02df88dcc2801fbd497eb247..9a48cc8b1b93a8ac449dc924a7e45ffe0e639df6 100644 (file)
--- a/src/target/cortex_a.c
+++ b/src/target/cortex_a.c
@@ -61,6 +61,7 @@
 #include "jtag/interface.h"
 #include "transport/transport.h"
 #include "smp.h"
+#include <helper/bits.h>
 #include <helper/time_support.h>
 
 static int cortex_a_poll(struct target *target);
@@ -1686,8 +1687,9 @@ static int cortex_a_set_watchpoint(struct target *target, struct watchpoint *wat
        int retval = ERROR_OK;
        int wrp_i = 0;
        uint32_t control;
-       uint8_t address_mask = ilog2(watchpoint->length);
-       uint8_t byte_address_select = 0xFF;
+       uint32_t address;
+       uint8_t address_mask;
+       uint8_t byte_address_select;
        uint8_t load_store_access_control = 0x3;
        struct cortex_a_common *cortex_a = target_to_cortex_a(target);
        struct armv7a_common *armv7a = &cortex_a->armv7a_common;
@@ -1707,18 +1709,52 @@ static int cortex_a_set_watchpoint(struct target *target, struct watchpoint *wat
                return ERROR_FAIL;
        }
 
-       if (address_mask == 0x1 || address_mask == 0x2) {
-               LOG_WARNING("length must be a power of 2 and different than 2 and 4");
+       if (watchpoint->length == 0 || watchpoint->length > 0x80000000U ||
+                       (watchpoint->length & (watchpoint->length - 1))) {
+               LOG_WARNING("watchpoint length must be a power of 2");
                return ERROR_FAIL;
        }
 
+       if (watchpoint->address & (watchpoint->length - 1)) {
+               LOG_WARNING("watchpoint address must be aligned at length");
+               return ERROR_FAIL;
+       }
+
+       /* FIXME: ARM DDI 0406C: address_mask is optional. What to do if it's missing?  */
+       /* handle wp length 1 and 2 through byte select */
+       switch (watchpoint->length) {
+       case 1:
+               byte_address_select = BIT(watchpoint->address & 0x3);
+               address = watchpoint->address & ~0x3;
+               address_mask = 0;
+               break;
+
+       case 2:
+               byte_address_select = 0x03 << (watchpoint->address & 0x2);
+               address = watchpoint->address & ~0x3;
+               address_mask = 0;
+               break;
+
+       case 4:
+               byte_address_select = 0x0f;
+               address = watchpoint->address;
+               address_mask = 0;
+               break;
+
+       default:
+               byte_address_select = 0xff;
+               address = watchpoint->address;
+               address_mask = ilog2(watchpoint->length);
+               break;
+       }
+
        watchpoint->set = wrp_i + 1;
        control = (address_mask << 24) |
                (byte_address_select << 5) |
                (load_store_access_control << 3) |
                (0x3 << 1) | 1;
        wrp_list[wrp_i].used = 1;
-       wrp_list[wrp_i].value = (watchpoint->address & 0xFFFFFFFC);
+       wrp_list[wrp_i].value = address;
        wrp_list[wrp_i].control = control;
 
        retval = cortex_a_dap_write_memap_register_u32(target, armv7a->debug_base