flash/nor/at91samd: Add "nvmuserrow" command.

Add option "nvmuserrow" to "at91samd" for changing and reading the register at 0x804000 which represents various fuses.

Change-Id: I6382cc4ac15e6b9681e2f30b0ae60397a6289c3b
Signed-off-by: Stefan Arnold <sarnold@sh-sw.de>
Reviewed-on: http://openocd.zylin.com/4260
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

diff --git a/doc/openocd.texi b/doc/openocd.texi
index f6795e15b9f7162c4a7cbdf718436ef4e29c3238..d0a3d49b8d12b203437011812697258f53febf4a 100644 (file)
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -5319,6 +5319,26 @@ and prepares reset vector catch in case of reset halt.
 Command is used internally in event event reset-deassert-post.
 @end deffn
 
 Command is used internally in event event reset-deassert-post.
 @end deffn
 

+@deffn Command {at91samd nvmuserrow}
+Writes or reads the entire 64 bit wide NVM user row register which is located at
+0x804000. This register includes various fuses lock-bits and factory calibration
+data. Reading the register is done by invoking this command without any
+arguments. Writing is possible by giving 1 or 2 hex values. The first argument
+is the register value to be written and the second one is an optional changemask.
+Every bit which value in changemask is 0 will stay unchanged. The lock- and
+reserved-bits are masked out and cannot be changed.
+
+@example
+# Read user row
+>at91samd nvmuserrow
+NVMUSERROW: 0xFFFFFC5DD8E0C788
+# Write 0xFFFFFC5DD8E0C788 to user row
+>at91samd nvmuserrow 0xFFFFFC5DD8E0C788
+# Write 0x12300 to user row but leave other bits and low byte unchanged
+>at91samd nvmuserrow 0x12345 0xFFF00
+@end example
+@end deffn
+

 @end deffn
 
 @anchor{at91sam3}
 @end deffn
 
 @anchor{at91sam3}

diff --git a/src/flash/nor/at91samd.c b/src/flash/nor/at91samd.c
index 449a283ca7382982fe5102d4a819378d0e3626da..64716d96ffc6f16d544683b531897ac4613c4b4b 100644 (file)
--- a/src/flash/nor/at91samd.c
+++ b/src/flash/nor/at91samd.c
@@ -83,6 +83,9 @@
 #define SAMD_GET_SERIES(id) (((id >> 16) & 0x3F))
 #define SAMD_GET_DEVSEL(id) (id & 0xFF)
 
 #define SAMD_GET_SERIES(id) (((id >> 16) & 0x3F))
 #define SAMD_GET_DEVSEL(id) (id & 0xFF)
 

+/* Bits to mask out lockbits in user row */
+#define NVMUSERROW_LOCKBIT_MASK ((uint64_t)0x0000FFFFFFFFFFFF)
+

 struct samd_part {
        uint8_t id;
        const char *name;
 struct samd_part {
        uint8_t id;
        const char *name;


@@ -259,28 +262,38 @@ struct samd_family {
        uint8_t series;
        const struct samd_part *parts;
        size_t num_parts;
        uint8_t series;
        const struct samd_part *parts;
        size_t num_parts;

+       uint64_t nvm_userrow_res_mask; /* protect bits which are reserved, 0 -> protect */

 };
 
 /* Known SAMD families */
 static const struct samd_family samd_families[] = {
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_20,
 };
 
 /* Known SAMD families */
 static const struct samd_family samd_families[] = {
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_20,

-               samd20_parts, ARRAY_SIZE(samd20_parts) },
+               samd20_parts, ARRAY_SIZE(samd20_parts),
+               (uint64_t)0xFFFF01FFFE01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_21,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_21,

-               samd21_parts, ARRAY_SIZE(samd21_parts) },
+               samd21_parts, ARRAY_SIZE(samd21_parts),
+               (uint64_t)0xFFFF01FFFE01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_09,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_09,

-               samd09_parts, ARRAY_SIZE(samd09_parts) },
+               samd09_parts, ARRAY_SIZE(samd09_parts),
+               (uint64_t)0xFFFF01FFFE01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_10,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_10,

-               samd10_parts, ARRAY_SIZE(samd10_parts) },
+               samd10_parts, ARRAY_SIZE(samd10_parts),
+               (uint64_t)0xFFFF01FFFE01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_11,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_D, SAMD_SERIES_11,

-               samd11_parts, ARRAY_SIZE(samd11_parts) },
+               samd11_parts, ARRAY_SIZE(samd11_parts),
+               (uint64_t)0xFFFF01FFFE01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_L, SAMD_SERIES_21,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_L, SAMD_SERIES_21,

-               saml21_parts, ARRAY_SIZE(saml21_parts) },
+               saml21_parts, ARRAY_SIZE(saml21_parts),
+               (uint64_t)0xFFFF03FFFC01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_L, SAMD_SERIES_22,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_L, SAMD_SERIES_22,

-               saml22_parts, ARRAY_SIZE(saml22_parts) },
+               saml22_parts, ARRAY_SIZE(saml22_parts),
+               (uint64_t)0xFFFF03FFFC01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_C, SAMD_SERIES_20,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_C, SAMD_SERIES_20,

-               samc20_parts, ARRAY_SIZE(samc20_parts) },
+               samc20_parts, ARRAY_SIZE(samc20_parts),
+               (uint64_t)0xFFFF03FFFC01FF77 },

        { SAMD_PROCESSOR_M0, SAMD_FAMILY_C, SAMD_SERIES_21,
        { SAMD_PROCESSOR_M0, SAMD_FAMILY_C, SAMD_SERIES_21,

-               samc21_parts, ARRAY_SIZE(samc21_parts) },
+               samc21_parts, ARRAY_SIZE(samc21_parts),
+               (uint64_t)0xFFFF03FFFC01FF77 },

 };
 
 struct samd_info {
 };
 
 struct samd_info {


@@ -296,24 +309,42 @@ struct samd_info {
 
 static struct samd_info *samd_chips;
 
 
 static struct samd_info *samd_chips;
 

-
-
-static const struct samd_part *samd_find_part(uint32_t id)
+/**
+ * Gives the family structure to specific device id.
+ * @param id The id of the device.
+ * @return On failure NULL, otherwise a pointer to the structure.
+ */
+static const struct samd_family *samd_find_family(uint32_t id)

 {
        uint8_t processor = SAMD_GET_PROCESSOR(id);
        uint8_t family = SAMD_GET_FAMILY(id);
        uint8_t series = SAMD_GET_SERIES(id);
 {
        uint8_t processor = SAMD_GET_PROCESSOR(id);
        uint8_t family = SAMD_GET_FAMILY(id);
        uint8_t series = SAMD_GET_SERIES(id);

-       uint8_t devsel = SAMD_GET_DEVSEL(id);

 
        for (unsigned i = 0; i < ARRAY_SIZE(samd_families); i++) {
                if (samd_families[i].processor == processor &&
                        samd_families[i].series == series &&
 
        for (unsigned i = 0; i < ARRAY_SIZE(samd_families); i++) {
                if (samd_families[i].processor == processor &&
                        samd_families[i].series == series &&

-                       samd_families[i].family == family) {
-                       for (unsigned j = 0; j < samd_families[i].num_parts; j++) {
-                               if (samd_families[i].parts[j].id == devsel)
-                                       return &samd_families[i].parts[j];
-                       }
-               }
+                       samd_families[i].family == family)
+                       return &samd_families[i];
+       }
+
+       return NULL;
+}
+
+/**
+ * Gives the part structure to specific device id.
+ * @param id The id of the device.
+ * @return On failure NULL, otherwise a pointer to the structure.
+ */
+static const struct samd_part *samd_find_part(uint32_t id)
+{
+       uint8_t devsel = SAMD_GET_DEVSEL(id);
+       const struct samd_family *family = samd_find_family(id);
+       if (family == NULL)
+               return NULL;
+
+       for (unsigned i = 0; i < family->num_parts; i++) {
+               if (family->parts[i].id == devsel)
+                       return &family->parts[i];

        }
 
        return NULL;
        }
 
        return NULL;


@@ -484,6 +515,12 @@ static int samd_issue_nvmctrl_command(struct target *target, uint16_t cmd)
        return samd_check_error(target);
 }
 
        return samd_check_error(target);
 }
 

+/**
+ * Erases a flash-row at the given address.
+ * @param target Pointer to the target structure.
+ * @param address The address of the row.
+ * @return On success ERROR_OK, on failure an errorcode.
+ */

 static int samd_erase_row(struct target *target, uint32_t address)
 {
        int res;
 static int samd_erase_row(struct target *target, uint32_t address)
 {
        int res;


@@ -505,49 +542,62 @@ static int samd_erase_row(struct target *target, uint32_t address)
        return ERROR_OK;
 }
 
        return ERROR_OK;
 }
 

-static bool is_user_row_reserved_bit(uint8_t bit)
+/**
+ * Returns the bitmask of reserved bits in register.
+ * @param target Pointer to the target structure.
+ * @param mask Bitmask, 0 -> value stays untouched.
+ * @return On success ERROR_OK, on failure an errorcode.
+ */
+static int samd_get_reservedmask(struct target *target, uint64_t *mask)

 {
 {

-       /* See Table 9-3 in the SAMD20 datasheet for more information. */
-       switch (bit) {
-               /* Reserved bits */
-               case 3:
-               case 7:
-               /* Voltage regulator internal configuration with default value of 0x70,
-                * may not be changed. */
-               case 17 ... 24:
-               /* 41 is voltage regulator internal configuration and must not be
-                * changed.  42 through 47 are reserved. */
-               case 41 ... 47:
-                       return true;
-               default:
-                       break;
+       int res;
+       /* Get the devicetype */
+       uint32_t id;
+       res = target_read_u32(target, SAMD_DSU + SAMD_DSU_DID, &id);
+       if (res != ERROR_OK) {
+               LOG_ERROR("Couldn't read Device ID register");
+               return res;
+       }
+       const struct samd_family *family;
+       family = samd_find_family(id);
+       if (family == NULL) {
+               LOG_ERROR("Couldn't determine device family");
+               return ERROR_FAIL;

        }
        }

+       *mask = family->nvm_userrow_res_mask;
+       return ERROR_OK;
+}

 
 

-       return false;
+static int read_userrow(struct target *target, uint64_t *userrow)
+{
+       int res;
+       uint8_t buffer[8];
+
+       res = target_read_memory(target, SAMD_USER_ROW, 4, 2, buffer);
+       if (res != ERROR_OK)
+               return res;
+
+       *userrow = target_buffer_get_u64(target, buffer);
+       return ERROR_OK;

 }
 
 }
 

-/* Modify the contents of the User Row in Flash.  These are described in Table
- * 9-3 of the SAMD20 datasheet.  The User Row itself has a size of one page
- * and contains a combination of "fuses" and calibration data in bits 24:17.
- * We therefore try not to erase the row's contents unless we absolutely have
- * to and we don't permit modifying reserved bits. */
-static int samd_modify_user_row(struct target *target, uint32_t value,
-               uint8_t startb, uint8_t endb)
+/**
+ * Modify the contents of the User Row in Flash. The User Row itself
+ * has a size of one page and contains a combination of "fuses" and
+ * calibration data. Bits which have a value of zero in the mask will
+ * not be changed. Up to now devices only use the first 64 bits.
+ * @param target Pointer to the target structure.
+ * @param value_input The value to write.
+ * @param value_mask Bitmask, 0 -> value stays untouched.
+ * @return On success ERROR_OK, on failure an errorcode.
+ */
+static int samd_modify_user_row_masked(struct target *target,
+               uint64_t value_input, uint64_t value_mask)

 {
        int res;
        uint32_t nvm_ctrlb;
        bool manual_wp = true;
 
 {
        int res;
        uint32_t nvm_ctrlb;
        bool manual_wp = true;
 

-       if (is_user_row_reserved_bit(startb) || is_user_row_reserved_bit(endb)) {
-               LOG_ERROR("Can't modify bits in the requested range");
-               return ERROR_FAIL;
-       }
-
-       /* Check if we need to do manual page write commands */
-       res = target_read_u32(target, SAMD_NVMCTRL + SAMD_NVMCTRL_CTRLB, &nvm_ctrlb);
-       if (res == ERROR_OK)
-               manual_wp = (nvm_ctrlb & SAMD_NVM_CTRLB_MANW) != 0;
-

        /* Retrieve the MCU's page size, in bytes. This is also the size of the
         * entire User Row. */
        uint32_t page_size;
        /* Retrieve the MCU's page size, in bytes. This is also the size of the
         * entire User Row. */
        uint32_t page_size;


@@ -557,44 +607,49 @@ static int samd_modify_user_row(struct target *target, uint32_t value,
                return res;
        }
 
                return res;
        }
 

-       /* Make sure the size is sane before we allocate. */
-       assert(page_size > 0 && page_size <= SAMD_PAGE_SIZE_MAX);
-
-       /* Make sure we're within the single page that comprises the User Row. */
-       if (startb >= (page_size * 8) || endb >= (page_size * 8)) {
-               LOG_ERROR("Can't modify bits outside the User Row page range");
-               return ERROR_FAIL;
-       }
-
-       uint8_t *buf = malloc(page_size);
-       if (!buf)
-               return ERROR_FAIL;
+       /* Make sure the size is sane. */
+       assert(page_size <= SAMD_PAGE_SIZE_MAX &&
+               page_size >= sizeof(value_input));

 
 

+       uint8_t buf[SAMD_PAGE_SIZE_MAX];

        /* Read the user row (comprising one page) by words. */
        res = target_read_memory(target, SAMD_USER_ROW, 4, page_size / 4, buf);
        if (res != ERROR_OK)
        /* Read the user row (comprising one page) by words. */
        res = target_read_memory(target, SAMD_USER_ROW, 4, page_size / 4, buf);
        if (res != ERROR_OK)

-               goto out_user_row;
+               return res;
+
+       uint64_t value_device;
+       res = read_userrow(target, &value_device);
+       if (res != ERROR_OK)
+               return res;
+       uint64_t value_new = (value_input & value_mask) | (value_device & ~value_mask);

 
        /* We will need to erase before writing if the new value needs a '1' in any
         * position for which the current value had a '0'.  Otherwise we can avoid
         * erasing. */
 
        /* We will need to erase before writing if the new value needs a '1' in any
         * position for which the current value had a '0'.  Otherwise we can avoid
         * erasing. */

-       uint32_t cur = buf_get_u32(buf, startb, endb - startb + 1);
-       if ((~cur) & value) {
+       if ((~value_device) & value_new) {

                res = samd_erase_row(target, SAMD_USER_ROW);
                if (res != ERROR_OK) {
                        LOG_ERROR("Couldn't erase user row");
                res = samd_erase_row(target, SAMD_USER_ROW);
                if (res != ERROR_OK) {
                        LOG_ERROR("Couldn't erase user row");

-                       goto out_user_row;
+                       return res;

                }
        }
 
        /* Modify */
                }
        }
 
        /* Modify */

-       buf_set_u32(buf, startb, endb - startb + 1, value);
+       target_buffer_set_u64(target, buf, value_new);

 
        /* Write the page buffer back out to the target. */
        res = target_write_memory(target, SAMD_USER_ROW, 4, page_size / 4, buf);
        if (res != ERROR_OK)
 
        /* Write the page buffer back out to the target. */
        res = target_write_memory(target, SAMD_USER_ROW, 4, page_size / 4, buf);
        if (res != ERROR_OK)

-               goto out_user_row;
+               return res;

 
 

+       /* Check if we need to do manual page write commands */
+       res = target_read_u32(target, SAMD_NVMCTRL + SAMD_NVMCTRL_CTRLB, &nvm_ctrlb);
+       if (res == ERROR_OK)
+               manual_wp = (nvm_ctrlb & SAMD_NVM_CTRLB_MANW) != 0;
+       else {
+               LOG_ERROR("Read of NVM register CTRKB failed.");
+               return ERROR_FAIL;
+       }

        if (manual_wp) {
                /* Trigger flash write */
                res = samd_issue_nvmctrl_command(target, SAMD_NVM_CMD_WAP);
        if (manual_wp) {
                /* Trigger flash write */
                res = samd_issue_nvmctrl_command(target, SAMD_NVM_CMD_WAP);


@@ -602,12 +657,28 @@ static int samd_modify_user_row(struct target *target, uint32_t value,
                res = samd_check_error(target);
        }
 
                res = samd_check_error(target);
        }
 

-out_user_row:
-       free(buf);
-

        return res;
 }
 
        return res;
 }
 

+/**
+ * Modifies the user row register to the given value.
+ * @param target Pointer to the target structure.
+ * @param value The value to write.
+ * @param startb The bit-offset by which the given value is shifted.
+ * @param endb The bit-offset of the last bit in value to write.
+ * @return On success ERROR_OK, on failure an errorcode.
+ */
+static int samd_modify_user_row(struct target *target, uint64_t value,
+               uint8_t startb, uint8_t endb)
+{
+       uint64_t mask = 0;
+       int i;
+       for (i = startb ; i <= endb ; i++)
+               mask |= ((uint64_t)1) << i;
+
+       return samd_modify_user_row_masked(target, value << startb, mask);
+}
+

 static int samd_protect(struct flash_bank *bank, int set, int first_prot_bl, int last_prot_bl)
 {
        int res = ERROR_OK;
 static int samd_protect(struct flash_bank *bank, int set, int first_prot_bl, int last_prot_bl)
 {
        int res = ERROR_OK;


@@ -644,7 +715,8 @@ static int samd_protect(struct flash_bank *bank, int set, int first_prot_bl, int
         * corresponding to Sector 15.  A '1' means unlocked and a '0' means
         * locked.  See Table 9-3 in the SAMD20 datasheet for more details. */
 
         * corresponding to Sector 15.  A '1' means unlocked and a '0' means
         * locked.  See Table 9-3 in the SAMD20 datasheet for more details. */
 

-       res = samd_modify_user_row(bank->target, set ? 0x0000 : 0xFFFF,
+       res = samd_modify_user_row(bank->target,
+                       set ? (uint64_t)0 : (uint64_t)UINT64_MAX,

                        48 + first_prot_bl, 48 + last_prot_bl);
        if (res != ERROR_OK)
                LOG_WARNING("SAMD: protect settings were not made persistent!");
                        48 + first_prot_bl, 48 + last_prot_bl);
        if (res != ERROR_OK)
                LOG_WARNING("SAMD: protect settings were not made persistent!");


@@ -945,6 +1017,83 @@ COMMAND_HANDLER(samd_handle_eeprom_command)
        return res;
 }
 
        return res;
 }
 

+static COMMAND_HELPER(get_u64_from_hexarg, unsigned int num, uint64_t *value)
+{
+       if (num >= CMD_ARGC) {
+               command_print(CMD_CTX, "Too few Arguments.");
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       }
+
+       if (strlen(CMD_ARGV[num]) >= 3 &&
+               CMD_ARGV[num][0] == '0' &&
+               CMD_ARGV[num][1] == 'x') {
+               char *check = NULL;
+               *value = strtoull(&(CMD_ARGV[num][2]), &check, 16);
+               if ((value == 0 && errno == ERANGE) ||
+                       check == NULL || *check != 0) {
+                       command_print(CMD_CTX, "Invalid 64-bit hex value in argument %d.",
+                               num + 1);
+                       return ERROR_COMMAND_SYNTAX_ERROR;
+               }
+       } else {
+               command_print(CMD_CTX, "Argument %d needs to be a hex value.", num + 1);
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       }
+       return ERROR_OK;
+}
+
+COMMAND_HANDLER(samd_handle_nvmuserrow_command)
+{
+       int res = ERROR_OK;
+       struct target *target = get_current_target(CMD_CTX);
+
+       if (target) {
+               if (CMD_ARGC > 2) {
+                       command_print(CMD_CTX, "Too much Arguments given.");
+                       return ERROR_COMMAND_SYNTAX_ERROR;
+               }
+
+               if (CMD_ARGC > 0) {
+                       if (target->state != TARGET_HALTED) {
+                               LOG_ERROR("Target not halted.");
+                               return ERROR_TARGET_NOT_HALTED;
+                       }
+
+                       uint64_t mask;
+                       res = samd_get_reservedmask(target, &mask);
+                       if (res != ERROR_OK) {
+                               LOG_ERROR("Couldn't determine the mask for reserved bits.");
+                               return ERROR_FAIL;
+                       }
+                       mask &= NVMUSERROW_LOCKBIT_MASK;
+
+                       uint64_t value;
+                       res = CALL_COMMAND_HANDLER(get_u64_from_hexarg, 0, &value);
+                       if (res != ERROR_OK)
+                               return res;
+                       if (CMD_ARGC == 2) {
+                               uint64_t mask_temp;
+                               res = CALL_COMMAND_HANDLER(get_u64_from_hexarg, 1, &mask_temp);
+                               if (res != ERROR_OK)
+                                       return res;
+                               mask &= mask_temp;
+                       }
+                       res = samd_modify_user_row_masked(target, value, mask);
+                       if (res != ERROR_OK)
+                               return res;
+               }
+
+               /* read register */
+               uint64_t value;
+               res = read_userrow(target, &value);
+               if (res == ERROR_OK)
+                       command_print(CMD_CTX, "NVMUSERROW: 0x%016"PRIX64, value);
+               else
+                       LOG_ERROR("NVMUSERROW could not be read.");
+       }
+       return res;
+}
+

 COMMAND_HANDLER(samd_handle_bootloader_command)
 {
        int res = ERROR_OK;
 COMMAND_HANDLER(samd_handle_bootloader_command)
 {
        int res = ERROR_OK;


@@ -1050,29 +1199,29 @@ static const struct command_registration at91samd_exec_command_handlers[] = {
                .name = "dsu_reset_deassert",
                .handler = samd_handle_reset_deassert,
                .mode = COMMAND_EXEC,
                .name = "dsu_reset_deassert",
                .handler = samd_handle_reset_deassert,
                .mode = COMMAND_EXEC,

-               .help = "deasert internal reset held by DSU"
+               .help = "Deasert internal reset held by DSU."

        },
        {
                .name = "info",
                .handler = samd_handle_info_command,
                .mode = COMMAND_EXEC,
        },
        {
                .name = "info",
                .handler = samd_handle_info_command,
                .mode = COMMAND_EXEC,

-               .help = "Print information about the current at91samd chip"
+               .help = "Print information about the current at91samd chip "

                        "and its flash configuration.",
        },
        {
                .name = "chip-erase",
                .handler = samd_handle_chip_erase_command,
                .mode = COMMAND_EXEC,
                        "and its flash configuration.",
        },
        {
                .name = "chip-erase",
                .handler = samd_handle_chip_erase_command,
                .mode = COMMAND_EXEC,

-               .help = "Erase the entire Flash by using the Chip"
+               .help = "Erase the entire Flash by using the Chip-"

                        "Erase feature in the Device Service Unit (DSU).",
        },
        {
                .name = "set-security",
                .handler = samd_handle_set_security_command,
                .mode = COMMAND_EXEC,
                        "Erase feature in the Device Service Unit (DSU).",
        },
        {
                .name = "set-security",
                .handler = samd_handle_set_security_command,
                .mode = COMMAND_EXEC,

-               .help = "Secure the chip's Flash by setting the Security Bit."
-                       "This makes it impossible to read the Flash contents."
-                       "The only way to undo this is to issue the chip-erase"
+               .help = "Secure the chip's Flash by setting the Security Bit. "
+                       "This makes it impossible to read the Flash contents. "
+                       "The only way to undo this is to issue the chip-erase "

                        "command.",
        },
        {
                        "command.",
        },
        {


@@ -1080,9 +1229,9 @@ static const struct command_registration at91samd_exec_command_handlers[] = {
                .usage = "[size_in_bytes]",
                .handler = samd_handle_eeprom_command,
                .mode = COMMAND_EXEC,
                .usage = "[size_in_bytes]",
                .handler = samd_handle_eeprom_command,
                .mode = COMMAND_EXEC,

-               .help = "Show or set the EEPROM size setting, stored in the User Row."
-                       "Please see Table 20-3 of the SAMD20 datasheet for allowed values."
-                       "Changes are stored immediately but take affect after the MCU is"
+               .help = "Show or set the EEPROM size setting, stored in the User Row. "
+                       "Please see Table 20-3 of the SAMD20 datasheet for allowed values. "
+                       "Changes are stored immediately but take affect after the MCU is "

                        "reset.",
        },
        {
                        "reset.",
        },
        {


@@ -1090,11 +1239,22 @@ static const struct command_registration at91samd_exec_command_handlers[] = {
                .usage = "[size_in_bytes]",
                .handler = samd_handle_bootloader_command,
                .mode = COMMAND_EXEC,
                .usage = "[size_in_bytes]",
                .handler = samd_handle_bootloader_command,
                .mode = COMMAND_EXEC,

-               .help = "Show or set the bootloader size, stored in the User Row."
-                       "Please see Table 20-2 of the SAMD20 datasheet for allowed values."
-                       "Changes are stored immediately but take affect after the MCU is"
+               .help = "Show or set the bootloader size, stored in the User Row. "
+                       "Please see Table 20-2 of the SAMD20 datasheet for allowed values. "
+                       "Changes are stored immediately but take affect after the MCU is "

                        "reset.",
        },
                        "reset.",
        },

+       {
+               .name = "nvmuserrow",
+               .usage = "[value] [mask]",
+               .handler = samd_handle_nvmuserrow_command,
+               .mode = COMMAND_EXEC,
+               .help = "Show or set the nvmuserrow register. It is 64 bit wide "
+                       "and located at address 0x804000. Use the optional mask argument "
+                       "to prevent changes at positions where the bitvalue is zero. "
+                       "For security reasons the lock- and reserved-bits are masked out "
+                       "in background and therefore cannot be changed.",
+       },

        COMMAND_REGISTRATION_DONE
 };
 
        COMMAND_REGISTRATION_DONE
 };