stlink: fix handling of DPv1 and DPv2 banked registers

Arm DPv1 and DPv2 support banked registers by setting the bank in
field DPBANKSEL of register DP_SELECT.
Old ST-Link firmware don't support banked registers and setting a
bank other than bank zero on DPv1 or DPv2 cause issues in the
firmware because it cannot set back bank zero to read CTRL/STAT.
New ST-Link firmware mask away DPBANKSEL bits while writing in
DP_SELECT but support banked register using the same packed method
used by OpenOCD:
	#define BANK_REG(bank, reg) (((bank) << 4) | (reg))

Add a new macro STLINK_F_HAS_DPBANKSEL for firmware that support
arm DPv1 and DPv2, plus trigger an error if banked registers are
requested on old firmware.
Prevent changing DPBANKSEL on old firmware.
Log a debug message when changing DPBANKSEL will be ignored.

Change-Id: Iaa592517831d63f8da2290db54f6b32504e3081b
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4978
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

diff --git a/src/jtag/drivers/stlink_usb.c b/src/jtag/drivers/stlink_usb.c
index e121eb42b3075fbdb8e8bf7d62cf9a29d64a2d8d..5c904d4ffb6a94b9aabf73b5a76d2b9b7a7db67a 100644 (file)
--- a/src/jtag/drivers/stlink_usb.c
+++ b/src/jtag/drivers/stlink_usb.c
@@ -316,6 +316,7 @@ enum stlink_mode {
 #define STLINK_F_HAS_DAP_REG            BIT(5)
 #define STLINK_F_QUIRK_JTAG_DP_READ     BIT(6)
 #define STLINK_F_HAS_AP_INIT            BIT(7)
+#define STLINK_F_HAS_DPBANKSEL          BIT(8)
 
 /* aliases */
 #define STLINK_F_HAS_TARGET_VOLT        STLINK_F_HAS_TRACE
@@ -1021,6 +1022,10 @@ static int stlink_usb_version(void *handle)
                if (h->version.jtag >= 28)
                        flags |= STLINK_F_HAS_AP_INIT;
 
+               /* Banked regs (DPv1 & DPv2) support from V2J32 */
+               if (h->version.jtag >= 32)
+                       flags |= STLINK_F_HAS_DPBANKSEL;
+
                break;
        case 3:
                /* all STLINK-V3 use api-v3 */
@@ -1044,6 +1049,10 @@ static int stlink_usb_version(void *handle)
                /* API required to init AP before any AP access */
                flags |= STLINK_F_HAS_AP_INIT;
 
+               /* Banked regs (DPv1 & DPv2) support from V3J2 */
+               if (h->version.jtag >= 2)
+                       flags |= STLINK_F_HAS_DPBANKSEL;
+
                break;
        default:
                break;
@@ -3259,6 +3268,12 @@ static int stlink_dap_op_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
        uint32_t dummy;
        int retval;
 
+       if (!(stlink_dap_handle->version.flags & STLINK_F_HAS_DPBANKSEL))
+               if (reg & 0x000000F0) {
+                       LOG_ERROR("Banked DP registers not supported in current STLink FW");
+                       return ERROR_COMMAND_NOTFOUND;
+               }
+
        retval = stlink_dap_check_reconnect(dap);
        if (retval != ERROR_OK)
                return retval;
@@ -3286,6 +3301,18 @@ static int stlink_dap_op_queue_dp_write(struct adiv5_dap *dap, unsigned reg,
 {
        int retval;
 
+       if (!(stlink_dap_handle->version.flags & STLINK_F_HAS_DPBANKSEL))
+               if (reg & 0x000000F0) {
+                       LOG_ERROR("Banked DP registers not supported in current STLink FW");
+                       return ERROR_COMMAND_NOTFOUND;
+               }
+
+       if (reg == DP_SELECT && (data & DP_SELECT_DPBANK) != 0) {
+               /* ignored if STLINK_F_HAS_DPBANKSEL, not properly managed otherwise */
+               LOG_DEBUG("Ignoring DPBANKSEL while write SELECT");
+               data &= ~DP_SELECT_DPBANK;
+       }
+
        retval = stlink_dap_check_reconnect(dap);
        if (retval != ERROR_OK)
                return retval;