openocd: fix SPDX tag format for files .c
[fw/openocd] / src / flash / nor / nrf5.c
index db54ddb6ff8f0e7de90ed7258d0ed4fa73f7c5a7..d5de4a4644b338942fc9610ea7df315f3993b564 100644 (file)
@@ -1,21 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
 /***************************************************************************
  *   Copyright (C) 2013 Synapse Product Development                        *
  *   Andrey Smirnov <andrew.smironv@gmail.com>                             *
  *   Angus Gratton <gus@projectgus.com>                                    *
  *   Erdem U. Altunyurt <spamjunkeater@gmail.com>                          *
- *                                                                         *
- *   This program is free software; you can redistribute it and/or modify  *
- *   it under the terms of the GNU General Public License as published by  *
- *   the Free Software Foundation; either version 2 of the License, or     *
- *   (at your option) any later version.                                   *
- *                                                                         *
- *   This program is distributed in the hope that it will be useful,       *
- *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
- *   GNU General Public License for more details.                          *
- *                                                                         *
- *   You should have received a copy of the GNU General Public License     *
- *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
  ***************************************************************************/
 
 #ifdef HAVE_CONFIG_H
 #endif
 
 #include "imp.h"
+#include <helper/binarybuffer.h>
 #include <target/algorithm.h>
 #include <target/armv7m.h>
 #include <helper/types.h>
 #include <helper/time_support.h>
 
+/* Both those values are constant across the current spectrum ofr nRF5 devices */
+#define WATCHDOG_REFRESH_REGISTER       0x40010600
+#define WATCHDOG_REFRESH_VALUE          0x6e524635
+
 enum {
        NRF5_FLASH_BASE = 0x00000000,
 };
@@ -85,7 +79,7 @@ enum nrf5_ficr_registers {
 
 enum nrf5_uicr_registers {
        NRF5_UICR_BASE = 0x10001000, /* User Information
-                                      * Configuration Regsters */
+                                      * Configuration Registers */
 
 #define NRF5_UICR_REG(offset) (NRF5_UICR_BASE + offset)
 
@@ -142,7 +136,7 @@ struct nrf5_device_spec {
 };
 
 struct nrf5_info {
-       uint32_t refcount;
+       unsigned int refcount;
 
        struct nrf5_bank {
                struct nrf5_info *chip;
@@ -154,9 +148,10 @@ struct nrf5_info {
        bool ficr_info_valid;
        struct nrf52_ficr_info ficr_info;
        const struct nrf5_device_spec *spec;
-       uint32_t hwid;
+       uint16_t hwid;
        enum nrf5_features features;
        unsigned int flash_size_kb;
+       unsigned int ram_size_kb;
 };
 
 #define NRF51_DEVICE_DEF(id, pt, var, bcode, fsize) \
@@ -251,7 +246,7 @@ static const struct nrf5_device_spec nrf5_known_devices_table[] = {
        NRF51_DEVICE_DEF(0x007A, "51422", "CEAA", "C0",    256),
        NRF51_DEVICE_DEF(0x0088, "51422", "CFAC", "A0",    256),
 
-       /* The driver fully autodects nRF52 series devices by FICR INFO,
+       /* The driver fully autodetects nRF52 series devices by FICR INFO,
         * no need for nRF52xxx HWIDs in this table */
 #if 0
        /* nRF52810 Devices */
@@ -282,11 +277,13 @@ static const struct nrf5_device_package nrf5_packages_table[] = {
        { 0x2005, "CK" },
 };
 
-static int nrf5_bank_is_probed(struct flash_bank *bank)
+const struct flash_driver nrf5_flash, nrf51_flash;
+
+static bool nrf5_bank_is_probed(const struct flash_bank *bank)
 {
        struct nrf5_bank *nbank = bank->driver_priv;
 
-       assert(nbank != NULL);
+       assert(nbank);
 
        return nbank->probed;
 }
@@ -302,13 +299,10 @@ static int nrf5_get_probed_chip_if_halted(struct flash_bank *bank, struct nrf5_i
        struct nrf5_bank *nbank = bank->driver_priv;
        *chip = nbank->chip;
 
-       int probed = nrf5_bank_is_probed(bank);
-       if (probed < 0)
-               return probed;
-       else if (!probed)
-               return nrf5_probe(bank);
-       else
+       if (nrf5_bank_is_probed(bank))
                return ERROR_OK;
+
+       return nrf5_probe(bank);
 }
 
 static int nrf5_wait_for_nvmc(struct nrf5_info *chip)
@@ -321,7 +315,7 @@ static int nrf5_wait_for_nvmc(struct nrf5_info *chip)
        do {
                res = target_read_u32(chip->target, NRF5_NVMC_READY, &ready);
                if (res != ERROR_OK) {
-                       LOG_ERROR("Couldn't read NVMC_READY register");
+                       LOG_ERROR("Error waiting NVMC_READY: generic flash write/erase error (check protection etc...)");
                        return res;
                }
 
@@ -433,18 +427,50 @@ error:
        return ERROR_FAIL;
 }
 
+static int nrf5_protect_check_clenr0(struct flash_bank *bank)
+{
+       int res;
+       uint32_t clenr0;
+       struct nrf5_bank *nbank = bank->driver_priv;
+       struct nrf5_info *chip = nbank->chip;
+
+       assert(chip);
+
+       res = target_read_u32(chip->target, NRF51_FICR_CLENR0,
+                             &clenr0);
+       if (res != ERROR_OK) {
+               LOG_ERROR("Couldn't read code region 0 size[FICR]");
+               return res;
+       }
+
+       if (clenr0 == 0xFFFFFFFF) {
+               res = target_read_u32(chip->target, NRF51_UICR_CLENR0,
+                                     &clenr0);
+               if (res != ERROR_OK) {
+                       LOG_ERROR("Couldn't read code region 0 size[UICR]");
+                       return res;
+               }
+       }
+
+       for (unsigned int i = 0; i < bank->num_sectors; i++)
+               bank->sectors[i].is_protected =
+                       clenr0 != 0xFFFFFFFF && bank->sectors[i].offset < clenr0;
+
+       return ERROR_OK;
+}
+
 static int nrf5_protect_check_bprot(struct flash_bank *bank)
 {
        struct nrf5_bank *nbank = bank->driver_priv;
        struct nrf5_info *chip = nbank->chip;
 
-       assert(chip != NULL);
+       assert(chip);
 
        static uint32_t nrf5_bprot_offsets[4] = { 0x600, 0x604, 0x610, 0x614 };
        uint32_t bprot_reg = 0;
        int res;
 
-       for (int i = 0; i < bank->num_sectors; i++) {
+       for (unsigned int i = 0; i < bank->num_sectors; i++) {
                unsigned int bit = i % 32;
                if (bit == 0) {
                        unsigned int n_reg = i / 32;
@@ -462,9 +488,6 @@ static int nrf5_protect_check_bprot(struct flash_bank *bank)
 
 static int nrf5_protect_check(struct flash_bank *bank)
 {
-       int res;
-       uint32_t clenr0;
-
        /* UICR cannot be write protected so just return early */
        if (bank->base == NRF5_UICR_BASE)
                return ERROR_OK;
@@ -472,60 +495,28 @@ static int nrf5_protect_check(struct flash_bank *bank)
        struct nrf5_bank *nbank = bank->driver_priv;
        struct nrf5_info *chip = nbank->chip;
 
-       assert(chip != NULL);
+       assert(chip);
 
        if (chip->features & NRF5_FEATURE_BPROT)
                return nrf5_protect_check_bprot(bank);
 
-       if (!(chip->features & NRF5_FEATURE_SERIES_51)) {
-               LOG_WARNING("Flash protection of this nRF device is not supported");
-               return ERROR_FLASH_OPER_UNSUPPORTED;
-       }
+       if (chip->features & NRF5_FEATURE_SERIES_51)
+               return nrf5_protect_check_clenr0(bank);
 
-       res = target_read_u32(chip->target, NRF51_FICR_CLENR0,
-                             &clenr0);
-       if (res != ERROR_OK) {
-               LOG_ERROR("Couldn't read code region 0 size[FICR]");
-               return res;
-       }
-
-       if (clenr0 == 0xFFFFFFFF) {
-               res = target_read_u32(chip->target, NRF51_UICR_CLENR0,
-                                     &clenr0);
-               if (res != ERROR_OK) {
-                       LOG_ERROR("Couldn't read code region 0 size[UICR]");
-                       return res;
-               }
-       }
-
-       for (int i = 0; i < bank->num_sectors; i++)
-               bank->sectors[i].is_protected =
-                       clenr0 != 0xFFFFFFFF && bank->sectors[i].offset < clenr0;
-
-       return ERROR_OK;
+       LOG_WARNING("Flash protection of this nRF device is not supported");
+       return ERROR_FLASH_OPER_UNSUPPORTED;
 }
 
-static int nrf5_protect(struct flash_bank *bank, int set, int first, int last)
+static int nrf5_protect_clenr0(struct flash_bank *bank, int set, unsigned int first,
+               unsigned int last)
 {
        int res;
        uint32_t clenr0, ppfc;
-       struct nrf5_info *chip;
-
-       /* UICR cannot be write protected so just bail out early */
-       if (bank->base == NRF5_UICR_BASE)
-               return ERROR_FAIL;
-
-       res = nrf5_get_probed_chip_if_halted(bank, &chip);
-       if (res != ERROR_OK)
-               return res;
-
-       if (!(chip->features & NRF5_FEATURE_SERIES_51)) {
-               LOG_ERROR("Flash protection setting of this nRF device is not supported");
-               return ERROR_FLASH_OPER_UNSUPPORTED;
-       }
+       struct nrf5_bank *nbank = bank->driver_priv;
+       struct nrf5_info *chip = nbank->chip;
 
        if (first != 0) {
-               LOG_ERROR("Code region 0 must start at the begining of the bank");
+               LOG_ERROR("Code region 0 must start at the beginning of the bank");
                return ERROR_FAIL;
        }
 
@@ -544,33 +535,71 @@ static int nrf5_protect(struct flash_bank *bank, int set, int first, int last)
        res = target_read_u32(chip->target, NRF51_UICR_CLENR0,
                              &clenr0);
        if (res != ERROR_OK) {
-               LOG_ERROR("Couldn't read code region 0 size[UICR]");
+               LOG_ERROR("Couldn't read code region 0 size from UICR");
                return res;
        }
 
-       if (clenr0 == 0xFFFFFFFF) {
-               res = target_write_u32(chip->target, NRF51_UICR_CLENR0,
-                                      clenr0);
-               if (res != ERROR_OK) {
-                       LOG_ERROR("Couldn't write code region 0 size[UICR]");
-                       return res;
-               }
-
-       } else {
+       if (!set || clenr0 != 0xFFFFFFFF) {
                LOG_ERROR("You need to perform chip erase before changing the protection settings");
+               return ERROR_FAIL;
        }
 
-       nrf5_protect_check(bank);
+       res = nrf5_nvmc_write_enable(chip);
+       if (res != ERROR_OK)
+               goto error;
 
-       return ERROR_OK;
+       clenr0 = bank->sectors[last].offset + bank->sectors[last].size;
+       res = target_write_u32(chip->target, NRF51_UICR_CLENR0, clenr0);
+
+       int res2 = nrf5_wait_for_nvmc(chip);
+
+       if (res == ERROR_OK)
+               res = res2;
+
+       if (res == ERROR_OK)
+               LOG_INFO("A reset or power cycle is required for the new protection settings to take effect.");
+       else
+               LOG_ERROR("Couldn't write code region 0 size to UICR");
+
+error:
+       nrf5_nvmc_read_only(chip);
+
+       return res;
+}
+
+static int nrf5_protect(struct flash_bank *bank, int set, unsigned int first,
+               unsigned int last)
+{
+       int res;
+       struct nrf5_info *chip;
+
+       /* UICR cannot be write protected so just bail out early */
+       if (bank->base == NRF5_UICR_BASE) {
+               LOG_ERROR("UICR page does not support protection");
+               return ERROR_FLASH_OPER_UNSUPPORTED;
+       }
+
+       res = nrf5_get_probed_chip_if_halted(bank, &chip);
+       if (res != ERROR_OK)
+               return res;
+
+       if (chip->features & NRF5_FEATURE_SERIES_51)
+               return nrf5_protect_clenr0(bank, set, first, last);
+
+       LOG_ERROR("Flash protection setting is not supported on this nRF5 device");
+       return ERROR_FLASH_OPER_UNSUPPORTED;
 }
 
 static bool nrf5_info_variant_to_str(uint32_t variant, char *bf)
 {
-       h_u32_to_be((uint8_t *)bf, variant);
-       bf[4] = '\0';
-       if (isalnum(bf[0]) && isalnum(bf[1]) && isalnum(bf[2]) && isalnum(bf[3]))
+       uint8_t b[4];
+
+       h_u32_to_be(b, variant);
+       if (isalnum(b[0]) && isalnum(b[1]) && isalnum(b[2]) && isalnum(b[3])) {
+               memcpy(bf, b, 4);
+               bf[4] = 0;
                return true;
+       }
 
        strcpy(bf, "xxxx");
        return false;
@@ -585,36 +614,45 @@ static const char *nrf5_decode_info_package(uint32_t package)
        return "xx";
 }
 
-static int nrf5_info(struct flash_bank *bank, char *buf, int buf_size)
+static int get_nrf5_chip_type_str(const struct nrf5_info *chip, char *buf, unsigned int buf_size)
 {
-       struct nrf5_bank *nbank = bank->driver_priv;
-       struct nrf5_info *chip = nbank->chip;
-
+       int res;
        if (chip->spec) {
-               snprintf(buf, buf_size,
-                               "nRF%s-%s(build code: %s) %ukB Flash",
-                               chip->spec->part, chip->spec->variant, chip->spec->build_code,
-                               chip->flash_size_kb);
-
+               res = snprintf(buf, buf_size, "nRF%s-%s(build code: %s)",
+                               chip->spec->part, chip->spec->variant, chip->spec->build_code);
        } else if (chip->ficr_info_valid) {
                char variant[5];
                nrf5_info_variant_to_str(chip->ficr_info.variant, variant);
-               snprintf(buf, buf_size,
-                               "nRF%" PRIx32 "-%s%.2s(build code: %s) %" PRIu32
-                               "kB Flash, %" PRIu32 "kB RAM",
+               res = snprintf(buf, buf_size, "nRF%" PRIx32 "-%s%.2s(build code: %s)",
                                chip->ficr_info.part,
                                nrf5_decode_info_package(chip->ficr_info.package),
-                               variant, &variant[2],
-                               chip->flash_size_kb,
-                               chip->ficr_info.ram);
-
+                               variant, &variant[2]);
        } else {
-               snprintf(buf, buf_size, "nRF51xxx (HWID 0x%04" PRIx16 ") %ukB Flash",
-                               chip->hwid, chip->flash_size_kb);
+               res = snprintf(buf, buf_size, "nRF51xxx (HWID 0x%04" PRIx16 ")", chip->hwid);
+       }
+
+       /* safety: */
+       if (res <= 0 || (unsigned int)res >= buf_size) {
+               LOG_ERROR("BUG: buffer problem in %s", __func__);
+               return ERROR_FAIL;
        }
        return ERROR_OK;
 }
 
+static int nrf5_info(struct flash_bank *bank, struct command_invocation *cmd)
+{
+       struct nrf5_bank *nbank = bank->driver_priv;
+       struct nrf5_info *chip = nbank->chip;
+
+       char chip_type_str[256];
+       if (get_nrf5_chip_type_str(chip, chip_type_str, sizeof(chip_type_str)) != ERROR_OK)
+               return ERROR_FAIL;
+
+       command_print_sameline(cmd, "%s %ukB Flash, %ukB RAM",
+                       chip_type_str, chip->flash_size_kb, chip->ram_size_kb);
+       return ERROR_OK;
+}
+
 static int nrf5_read_ficr_info(struct nrf5_info *chip)
 {
        int res;
@@ -681,6 +719,39 @@ static int nrf5_read_ficr_info(struct nrf5_info *chip)
        return ERROR_OK;
 }
 
+static int nrf5_get_ram_size(struct target *target, uint32_t *ram_size)
+{
+       int res;
+
+       *ram_size = 0;
+
+       uint32_t numramblock;
+       res = target_read_u32(target, NRF51_FICR_NUMRAMBLOCK, &numramblock);
+       if (res != ERROR_OK) {
+               LOG_DEBUG("Couldn't read FICR NUMRAMBLOCK register");
+               return res;
+       }
+
+       if (numramblock < 1 || numramblock > 4) {
+               LOG_DEBUG("FICR NUMRAMBLOCK strange value %" PRIx32, numramblock);
+               return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
+       }
+
+       for (unsigned int i = 0; i < numramblock; i++) {
+               uint32_t sizeramblock;
+               res = target_read_u32(target, NRF51_FICR_SIZERAMBLOCK0 + sizeof(uint32_t)*i, &sizeramblock);
+               if (res != ERROR_OK) {
+                       LOG_DEBUG("Couldn't read FICR NUMRAMBLOCK register");
+                       return res;
+               }
+               if (sizeramblock < 1024 || sizeramblock > 65536)
+                       LOG_DEBUG("FICR SIZERAMBLOCK strange value %" PRIx32, sizeramblock);
+               else
+                       *ram_size += sizeramblock;
+       }
+       return res;
+}
+
 static int nrf5_probe(struct flash_bank *bank)
 {
        int res;
@@ -688,14 +759,15 @@ static int nrf5_probe(struct flash_bank *bank)
        struct nrf5_info *chip = nbank->chip;
        struct target *target = chip->target;
 
-       res = target_read_u32(target, NRF5_FICR_CONFIGID, &chip->hwid);
+       uint32_t configid;
+       res = target_read_u32(target, NRF5_FICR_CONFIGID, &configid);
        if (res != ERROR_OK) {
                LOG_ERROR("Couldn't read CONFIGID register");
                return res;
        }
 
-       chip->hwid &= 0xFFFF;   /* HWID is stored in the lower two
-                        * bytes of the CONFIGID register */
+       /* HWID is stored in the lower two bytes of the CONFIGID register */
+       chip->hwid = configid & 0xFFFF;
 
        /* guess a nRF51 series if the device has no FICR INFO and we don't know HWID */
        chip->features = NRF5_FEATURE_SERIES_51;
@@ -720,6 +792,14 @@ static int nrf5_probe(struct flash_bank *bank)
                                                PRIx32, chip->hwid, chip->ficr_info.part);
        }
 
+       if (chip->ficr_info_valid) {
+               chip->ram_size_kb = chip->ficr_info.ram;
+       } else {
+               uint32_t ram_size;
+               nrf5_get_ram_size(target, &ram_size);
+               chip->ram_size_kb = ram_size / 1024;
+       }
+
        /* The value stored in NRF5_FICR_CODEPAGESIZE is the number of bytes in one page of FLASH. */
        uint32_t flash_page_size;
        res = target_read_u32(chip->target, NRF5_FICR_CODEPAGESIZE,
@@ -741,15 +821,19 @@ static int nrf5_probe(struct flash_bank *bank)
        chip->flash_size_kb = num_sectors * flash_page_size / 1024;
 
        if (!chip->bank[0].probed && !chip->bank[1].probed) {
-               char buf[80];
-               nrf5_info(bank, buf, sizeof(buf));
-               if (!chip->spec && !chip->ficr_info_valid) {
-                       LOG_INFO("Unknown device: %s", buf);
-               } else {
-                       LOG_INFO("%s", buf);
-               }
+               char chip_type_str[256];
+               if (get_nrf5_chip_type_str(chip, chip_type_str, sizeof(chip_type_str)) != ERROR_OK)
+                       return ERROR_FAIL;
+               const bool device_is_unknown = (!chip->spec && !chip->ficr_info_valid);
+               LOG_INFO("%s%s %ukB Flash, %ukB RAM",
+                               device_is_unknown ? "Unknown device: " : "",
+                               chip_type_str,
+                               chip->flash_size_kb,
+                               chip->ram_size_kb);
        }
 
+       free(bank->sectors);
+
        if (bank->base == NRF5_FLASH_BASE) {
                /* Sanity check */
                if (chip->spec && chip->flash_size_kb != chip->spec->flash_size_kb)
@@ -764,8 +848,6 @@ static int nrf5_probe(struct flash_bank *bank)
                if (!bank->sectors)
                        return ERROR_FAIL;
 
-               nrf5_protect_check(bank);
-
                chip->bank[0].probed = true;
 
        } else {
@@ -786,14 +868,10 @@ static int nrf5_probe(struct flash_bank *bank)
 
 static int nrf5_auto_probe(struct flash_bank *bank)
 {
-       int probed = nrf5_bank_is_probed(bank);
-
-       if (probed < 0)
-               return probed;
-       else if (probed)
+       if (nrf5_bank_is_probed(bank))
                return ERROR_OK;
-       else
-               return nrf5_probe(bank);
+
+       return nrf5_probe(bank);
 }
 
 static int nrf5_erase_all(struct nrf5_info *chip)
@@ -811,29 +889,27 @@ static int nrf5_erase_page(struct flash_bank *bank,
        int res;
 
        LOG_DEBUG("Erasing page at 0x%"PRIx32, sector->offset);
-       if (sector->is_protected) {
-               LOG_ERROR("Cannot erase protected sector at 0x%" PRIx32, sector->offset);
-               return ERROR_FAIL;
-       }
 
        if (bank->base == NRF5_UICR_BASE) {
-               uint32_t ppfc;
-               res = target_read_u32(chip->target, NRF51_FICR_PPFC,
+               if (chip->features & NRF5_FEATURE_SERIES_51) {
+                       uint32_t ppfc;
+                       res = target_read_u32(chip->target, NRF51_FICR_PPFC,
                                      &ppfc);
-               if (res != ERROR_OK) {
-                       LOG_ERROR("Couldn't read PPFC register");
-                       return res;
-               }
-
-               if ((ppfc & 0xFF) == 0xFF) {
-                       /* We can't erase the UICR.  Double-check to
-                          see if it's already erased before complaining. */
-                       default_flash_blank_check(bank);
-                       if (sector->is_erased == 1)
-                               return ERROR_OK;
-
-                       LOG_ERROR("The chip was not pre-programmed with SoftDevice stack and UICR cannot be erased separately. Please issue mass erase before trying to write to this region");
-                       return ERROR_FAIL;
+                       if (res != ERROR_OK) {
+                               LOG_ERROR("Couldn't read PPFC register");
+                               return res;
+                       }
+
+                       if ((ppfc & 0xFF) == 0xFF) {
+                               /* We can't erase the UICR.  Double-check to
+                                  see if it's already erased before complaining. */
+                               default_flash_blank_check(bank);
+                               if (sector->is_erased == 1)
+                                       return ERROR_OK;
+
+                               LOG_ERROR("The chip was not pre-programmed with SoftDevice stack and UICR cannot be erased separately. Please issue mass erase before trying to write to this region");
+                               return ERROR_FAIL;
+                       }
                }
 
                res = nrf5_nvmc_generic_erase(chip,
@@ -850,30 +926,6 @@ static int nrf5_erase_page(struct flash_bank *bank,
        return res;
 }
 
-static const uint8_t nrf5_flash_write_code[] = {
-       /* See contrib/loaders/flash/cortex-m0.S */
-/* <wait_fifo>: */
-       0x0d, 0x68,             /* ldr  r5,     [r1,    #0] */
-       0x00, 0x2d,             /* cmp  r5,     #0 */
-       0x0b, 0xd0,             /* beq.n        1e <exit> */
-       0x4c, 0x68,             /* ldr  r4,     [r1,    #4] */
-       0xac, 0x42,             /* cmp  r4,     r5 */
-       0xf9, 0xd0,             /* beq.n        0 <wait_fifo> */
-       0x20, 0xcc,             /* ldmia        r4!,    {r5} */
-       0x20, 0xc3,             /* stmia        r3!,    {r5} */
-       0x94, 0x42,             /* cmp  r4,     r2 */
-       0x01, 0xd3,             /* bcc.n        18 <no_wrap> */
-       0x0c, 0x46,             /* mov  r4,     r1 */
-       0x08, 0x34,             /* adds r4,     #8 */
-/* <no_wrap>: */
-       0x4c, 0x60,             /* str  r4, [r1,        #4] */
-       0x04, 0x38,             /* subs r0, #4 */
-       0xf0, 0xd1,             /* bne.n        0 <wait_fifo> */
-/* <exit>: */
-       0x00, 0xbe              /* bkpt 0x0000 */
-};
-
-
 /* Start a low level flash write for the specified region */
 static int nrf5_ll_flash_write(struct nrf5_info *chip, uint32_t address, const uint8_t *buffer, uint32_t bytes)
 {
@@ -881,10 +933,14 @@ static int nrf5_ll_flash_write(struct nrf5_info *chip, uint32_t address, const u
        uint32_t buffer_size = 8192;
        struct working_area *write_algorithm;
        struct working_area *source;
-       struct reg_param reg_params[4];
+       struct reg_param reg_params[6];
        struct armv7m_algorithm armv7m_info;
        int retval = ERROR_OK;
 
+       static const uint8_t nrf5_flash_write_code[] = {
+#include "../../../contrib/loaders/flash/nrf5/nrf5.inc"
+       };
+
        LOG_DEBUG("Writing buffer to flash address=0x%"PRIx32" bytes=0x%"PRIx32, address, bytes);
        assert(bytes % 4 == 0);
 
@@ -935,17 +991,21 @@ static int nrf5_ll_flash_write(struct nrf5_info *chip, uint32_t address, const u
        init_reg_param(&reg_params[1], "r1", 32, PARAM_OUT);    /* buffer start */
        init_reg_param(&reg_params[2], "r2", 32, PARAM_OUT);    /* buffer end */
        init_reg_param(&reg_params[3], "r3", 32, PARAM_IN_OUT); /* target address */
+       init_reg_param(&reg_params[4], "r6", 32, PARAM_OUT);    /* watchdog refresh value */
+       init_reg_param(&reg_params[5], "r7", 32, PARAM_OUT);    /* watchdog refresh register address */
 
        buf_set_u32(reg_params[0].value, 0, 32, bytes);
        buf_set_u32(reg_params[1].value, 0, 32, source->address);
        buf_set_u32(reg_params[2].value, 0, 32, source->address + source->size);
        buf_set_u32(reg_params[3].value, 0, 32, address);
+       buf_set_u32(reg_params[4].value, 0, 32, WATCHDOG_REFRESH_VALUE);
+       buf_set_u32(reg_params[5].value, 0, 32, WATCHDOG_REFRESH_REGISTER);
 
        retval = target_run_flash_async_algorithm(target, buffer, bytes/4, 4,
                        0, NULL,
-                       4, reg_params,
+                       ARRAY_SIZE(reg_params), reg_params,
                        source->address, source->size,
-                       write_algorithm->address, 0,
+                       write_algorithm->address, write_algorithm->address + sizeof(nrf5_flash_write_code) - 2,
                        &armv7m_info);
 
        target_free_working_area(target, source);
@@ -955,6 +1015,8 @@ static int nrf5_ll_flash_write(struct nrf5_info *chip, uint32_t address, const u
        destroy_reg_param(&reg_params[1]);
        destroy_reg_param(&reg_params[2]);
        destroy_reg_param(&reg_params[3]);
+       destroy_reg_param(&reg_params[4]);
+       destroy_reg_param(&reg_params[5]);
 
        return retval;
 }
@@ -971,6 +1033,34 @@ static int nrf5_write(struct flash_bank *bank, const uint8_t *buffer,
        assert(offset % 4 == 0);
        assert(count % 4 == 0);
 
+       /* UICR CLENR0 based protection used on nRF51 is somewhat clumsy:
+        * RM reads: Code running from code region 1 will not be able to write
+        * to code region 0.
+        * Unfortunately the flash loader running from RAM can write to both
+        * code regions without any hint the protection is violated.
+        *
+        * Update protection state and check if any flash sector to be written
+        * is protected. */
+       if (chip->features & NRF5_FEATURE_SERIES_51) {
+
+               res = nrf5_protect_check_clenr0(bank);
+               if (res != ERROR_OK)
+                       return res;
+
+               for (unsigned int sector = 0; sector < bank->num_sectors; sector++) {
+                       struct flash_sector *bs = &bank->sectors[sector];
+
+                       /* Start offset in or before this sector? */
+                       /* End offset in or behind this sector? */
+                       if ((offset < (bs->offset + bs->size))
+                                       && ((offset + count - 1) >= bs->offset)
+                                       && bs->is_protected == 1) {
+                               LOG_ERROR("Write refused, sector %d is protected", sector);
+                               return ERROR_FLASH_PROTECTED;
+                       }
+               }
+       }
+
        res = nrf5_nvmc_write_enable(chip);
        if (res != ERROR_OK)
                goto error;
@@ -987,7 +1077,8 @@ error:
        return res;
 }
 
-static int nrf5_erase(struct flash_bank *bank, int first, int last)
+static int nrf5_erase(struct flash_bank *bank, unsigned int first,
+               unsigned int last)
 {
        int res;
        struct nrf5_info *chip;
@@ -996,18 +1087,43 @@ static int nrf5_erase(struct flash_bank *bank, int first, int last)
        if (res != ERROR_OK)
                return res;
 
+       /* UICR CLENR0 based protection used on nRF51 prevents erase
+        * absolutely silently. NVMC has no flag to indicate the protection
+        * was violated.
+        *
+        * Update protection state and check if any flash sector to be erased
+        * is protected. */
+       if (chip->features & NRF5_FEATURE_SERIES_51) {
+
+               res = nrf5_protect_check_clenr0(bank);
+               if (res != ERROR_OK)
+                       return res;
+       }
+
        /* For each sector to be erased */
-       for (int s = first; s <= last && res == ERROR_OK; s++)
+       for (unsigned int s = first; s <= last && res == ERROR_OK; s++) {
+
+               if (chip->features & NRF5_FEATURE_SERIES_51
+                               && bank->sectors[s].is_protected == 1) {
+                       LOG_ERROR("Flash sector %d is protected", s);
+                       return ERROR_FLASH_PROTECTED;
+               }
+
                res = nrf5_erase_page(bank, chip, &bank->sectors[s]);
+               if (res != ERROR_OK) {
+                       LOG_ERROR("Error erasing sector %d", s);
+                       return res;
+               }
+       }
 
-       return res;
+       return ERROR_OK;
 }
 
 static void nrf5_free_driver_priv(struct flash_bank *bank)
 {
        struct nrf5_bank *nbank = bank->driver_priv;
        struct nrf5_info *chip = nbank->chip;
-       if (chip == NULL)
+       if (!chip)
                return;
 
        chip->refcount--;
@@ -1017,9 +1133,31 @@ static void nrf5_free_driver_priv(struct flash_bank *bank)
        }
 }
 
+static struct nrf5_info *nrf5_get_chip(struct target *target)
+{
+       struct flash_bank *bank_iter;
+
+       /* iterate over nrf5 banks of same target */
+       for (bank_iter = flash_bank_list(); bank_iter; bank_iter = bank_iter->next) {
+               if (bank_iter->driver != &nrf5_flash && bank_iter->driver != &nrf51_flash)
+                       continue;
+
+               if (bank_iter->target != target)
+                       continue;
+
+               struct nrf5_bank *nbank = bank_iter->driver_priv;
+               if (!nbank)
+                       continue;
+
+               if (nbank->chip)
+                       return nbank->chip;
+       }
+       return NULL;
+}
+
 FLASH_BANK_COMMAND_HANDLER(nrf5_flash_bank_command)
 {
-       static struct nrf5_info *chip;
+       struct nrf5_info *chip;
        struct nrf5_bank *nbank = NULL;
 
        switch (bank->base) {
@@ -1031,6 +1169,7 @@ FLASH_BANK_COMMAND_HANDLER(nrf5_flash_bank_command)
                return ERROR_FAIL;
        }
 
+       chip = nrf5_get_chip(bank->target);
        if (!chip) {
                /* Create a new chip */
                chip = calloc(1, sizeof(*chip));
@@ -1048,7 +1187,7 @@ FLASH_BANK_COMMAND_HANDLER(nrf5_flash_bank_command)
                nbank = &chip->bank[1];
                break;
        }
-       assert(nbank != NULL);
+       assert(nbank);
 
        chip->refcount++;
        nbank->chip = chip;
@@ -1069,7 +1208,7 @@ COMMAND_HANDLER(nrf5_handle_mass_erase_command)
        if (res != ERROR_OK)
                return res;
 
-       assert(bank != NULL);
+       assert(bank);
 
        struct nrf5_info *chip;
 
@@ -1077,39 +1216,33 @@ COMMAND_HANDLER(nrf5_handle_mass_erase_command)
        if (res != ERROR_OK)
                return res;
 
-       uint32_t ppfc;
-
-       res = target_read_u32(target, NRF51_FICR_PPFC,
+       if (chip->features & NRF5_FEATURE_SERIES_51) {
+               uint32_t ppfc;
+               res = target_read_u32(target, NRF51_FICR_PPFC,
                              &ppfc);
-       if (res != ERROR_OK) {
-               LOG_ERROR("Couldn't read PPFC register");
-               return res;
-       }
+               if (res != ERROR_OK) {
+                       LOG_ERROR("Couldn't read PPFC register");
+                       return res;
+               }
 
-       if ((ppfc & 0xFF) == 0x00) {
-               LOG_ERROR("Code region 0 size was pre-programmed at the factory, "
-                         "mass erase command won't work.");
-               return ERROR_FAIL;
+               if ((ppfc & 0xFF) == 0x00) {
+                       LOG_ERROR("Code region 0 size was pre-programmed at the factory, "
+                                 "mass erase command won't work.");
+                       return ERROR_FAIL;
+               }
        }
 
        res = nrf5_erase_all(chip);
-       if (res != ERROR_OK) {
-               LOG_ERROR("Failed to erase the chip");
-               nrf5_protect_check(bank);
-               return res;
-       }
+       if (res == ERROR_OK) {
+               LOG_INFO("Mass erase completed.");
+               if (chip->features & NRF5_FEATURE_SERIES_51)
+                       LOG_INFO("A reset or power cycle is required if the flash was protected before.");
 
-       res = nrf5_protect_check(bank);
-       if (res != ERROR_OK) {
-               LOG_ERROR("Failed to check chip's write protection");
-               return res;
+       } else {
+               LOG_ERROR("Failed to erase the chip");
        }
 
-       res = get_flash_bank_by_addr(target, NRF5_UICR_BASE, true, &bank);
-       if (res != ERROR_OK)
-               return res;
-
-       return ERROR_OK;
+       return res;
 }
 
 COMMAND_HANDLER(nrf5_handle_info_command)
@@ -1122,7 +1255,7 @@ COMMAND_HANDLER(nrf5_handle_info_command)
        if (res != ERROR_OK)
                return res;
 
-       assert(bank != NULL);
+       assert(bank);
 
        struct nrf5_info *chip;
 
@@ -1297,7 +1430,7 @@ const struct flash_driver nrf5_flash = {
 };
 
 /* We need to retain the flash-driver name as well as the commands
- * for backwards compatability */
+ * for backwards compatibility */
 const struct flash_driver nrf51_flash = {
        .name                   = "nrf51",
        .commands               = nrf5_command_handlers,