This patch adds support for nRF52 series devices.  It is patchset 7 from
<http://openocd.zylin.com/#/c/3511/>, which has been tested, but not
merged yet in master.

From: Michael Dietz <mjdietzx@gmail.com>
Date: Mon, 30 May 2016 12:50:44 +0000 (-0700)
Subject: Added support for nRF52 Series Devices.
X-Git-Url: http://openocd.zylin.com/gitweb?p=openocd.git;a=commitdiff_plain;h=9ba15633e221d9d72e320372ba8f49d3f30d4bce

Added support for nRF52 Series Devices.

Both nrf52.c and nrf52.cfg are based off of previous nRF51 files.
- Some possible race conditions with NVMC have been fixed in nRF52.c
- Removed nrf51_get_probed_chip_if_halted() as the core does not have to be halted to perform operations where it is called.
- Only registers that are needed by openOCD are defined, some registers in nRF51 don't exist in nRF52 and are removed.
- Some all around cleanup has been done.
- The protection mechanism is completely different on nRF52 and this has not been implemented yet - just prints a warning and returns for now.

Change-Id: I4dd42c86f33f450709bb981806c2655f04aa6201
Signed-off-by: Michael Dietz <mjdietzx@gmail.com>
---

diff --git a/src/flash/nor/Makefile.am b/src/flash/nor/Makefile.am
index 727e4f2..839667c 100644
--- a/src/flash/nor/Makefile.am
+++ b/src/flash/nor/Makefile.am
@@ -36,6 +36,7 @@ NOR_DRIVERS = \
 	%D%/niietcm4.c \
 	%D%/non_cfi.c \
 	%D%/nrf51.c \
+	%D%/nrf52.c \
 	%D%/numicro.c \
 	%D%/ocl.c \
 	%D%/pic32mx.c \
diff --git a/src/flash/nor/drivers.c b/src/flash/nor/drivers.c
index 56a5cb2..071273e 100644
--- a/src/flash/nor/drivers.c
+++ b/src/flash/nor/drivers.c
@@ -48,6 +48,7 @@ extern struct flash_driver mdr_flash;
 extern struct flash_driver mrvlqspi_flash;
 extern struct flash_driver niietcm4_flash;
 extern struct flash_driver nrf51_flash;
+extern struct flash_driver nrf52_flash;
 extern struct flash_driver numicro_flash;
 extern struct flash_driver ocl_flash;
 extern struct flash_driver pic32mx_flash;
@@ -100,6 +101,7 @@ static struct flash_driver *flash_drivers[] = {
 	&mrvlqspi_flash,
 	&niietcm4_flash,
 	&nrf51_flash,
+       &nrf52_flash,
 	&numicro_flash,
 	&ocl_flash,
 	&pic32mx_flash,
diff --git a/src/flash/nor/nrf52.c b/src/flash/nor/nrf52.c
new file mode 100644
index 0000000..7f2bd35
--- /dev/null
+++ b/src/flash/nor/nrf52.c
@@ -0,0 +1,733 @@
+/***************************************************************************
+ *   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
+#include "config.h"
+#endif
+
+#include <stdlib.h>
+
+#include "imp.h"
+#include <target/algorithm.h>
+#include <target/armv7m.h>
+#include <helper/types.h>
+
+/* nRF52 Register addresses used by openOCD. */
+#define NRF52_FLASH_BASE_ADDR        (0x0)
+
+#define NRF52_FICR_BASE_ADDR         (0x10000000)
+#define NRF52_FICR_CODEPAGESIZE_ADDR (NRF52_FICR_BASE_ADDR | 0x010)
+#define NRF52_FICR_CODESIZE_ADDR     (NRF52_FICR_BASE_ADDR | 0x014)
+
+#define NRF52_UICR_BASE_ADDR         (0x10001000)
+
+#define NRF52_NVMC_BASE_ADDR         (0x4001E000)
+#define NRF52_NVMC_READY_ADDR        (NRF52_NVMC_BASE_ADDR | 0x400)
+#define NRF52_NVMC_CONFIG_ADDR       (NRF52_NVMC_BASE_ADDR | 0x504)
+#define NRF52_NVMC_ERASEPAGE_ADDR    (NRF52_NVMC_BASE_ADDR | 0x508)
+#define NRF52_NVMC_ERASEALL_ADDR     (NRF52_NVMC_BASE_ADDR | 0x50C)
+#define NRF52_NVMC_ERASEUICR_ADDR    (NRF52_NVMC_BASE_ADDR | 0x514)
+
+/* nRF52 bit fields. */
+enum nrf52_nvmc_config_bits {
+	NRF52_NVMC_CONFIG_REN = 0x0,
+	NRF52_NVMC_CONFIG_WEN = 0x01,
+	NRF52_NVMC_CONFIG_EEN = 0x02
+};
+
+enum nrf52_nvmc_ready_bits {
+	NRF52_NVMC_BUSY  = 0x0,
+	NRF52_NVMC_READY = 0x01
+};
+
+/* nRF52 state information. */
+struct nrf52_info {
+	uint32_t code_page_size; /* Size of FLASH page in bytes. */
+	uint32_t code_memory_size; /* Size of Code FLASH region in bytes. */
+
+	struct {
+		bool probed;
+		int (*write) (struct flash_bank *bank,
+				struct nrf52_info *chip,
+				const uint8_t *buffer, uint32_t offset, uint32_t count);
+	} bank[2]; /* There are two regions in nRF52 FLASH - Code and UICR. */
+	struct target *target;
+};
+
+static int nrf52_protect_check(struct flash_bank *bank);
+
+static int nrf52_probe(struct flash_bank *bank)
+{
+	int res;
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	res = target_read_u32(chip->target,
+						NRF52_FICR_CODEPAGESIZE_ADDR,
+						&chip->code_page_size);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Couldn't read code page size");
+		return res;
+	}
+
+	res = target_read_u32(chip->target,
+						NRF52_FICR_CODESIZE_ADDR,
+						&chip->code_memory_size);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Couldn't read code memory size");
+		return res;
+	}
+
+	chip->code_memory_size = chip->code_memory_size * chip->code_page_size;
+
+	if (bank->base == NRF52_FLASH_BASE_ADDR) {
+		bank->size = chip->code_memory_size;
+		bank->num_sectors = bank->size / chip->code_page_size;
+		bank->sectors = calloc(bank->num_sectors,
+							sizeof((bank->sectors)[0]));
+		if (!bank->sectors)
+			return ERROR_FLASH_BANK_NOT_PROBED;
+
+		/* Fill out the sector information: All nRF51 sectors are the same size. */
+		for (int i = 0; i < bank->num_sectors; i++) {
+			bank->sectors[i].size = chip->code_page_size;
+			bank->sectors[i].offset	= i * chip->code_page_size;
+
+			/* Mark as unknown. */
+			bank->sectors[i].is_erased = -1;
+			bank->sectors[i].is_protected = -1;
+		}
+
+		nrf52_protect_check(bank);
+
+		chip->bank[0].probed = true;
+	} else { /* This is the UICR bank. */
+		bank->size = chip->code_page_size;
+		bank->num_sectors = 1;
+		bank->sectors = calloc(bank->num_sectors,
+							sizeof((bank->sectors)[0]));
+		if (!bank->sectors)
+			return ERROR_FLASH_BANK_NOT_PROBED;
+
+		bank->sectors[0].size = bank->size;
+		bank->sectors[0].offset	= 0;
+
+		bank->sectors[0].is_erased = -1;
+		bank->sectors[0].is_protected = -1;
+
+		chip->bank[1].probed = true;
+	}
+
+	return ERROR_OK;
+}
+
+static int nrf52_bank_is_probed(struct flash_bank *bank)
+{
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	return chip->bank[bank->bank_number].probed;
+}
+
+static int nrf52_auto_probe(struct flash_bank *bank)
+{
+	if (!nrf52_bank_is_probed(bank))
+		return nrf52_probe(bank);
+	else
+		return ERROR_OK;
+}
+
+static int nrf52_wait_for_nvmc(struct nrf52_info *chip)
+{
+	int res;
+	uint32_t ready;
+	int timeout = 100;
+
+	do {
+		res = target_read_u32(chip->target, NRF52_NVMC_READY_ADDR, &ready);
+		if (res != ERROR_OK) {
+			LOG_ERROR("Couldn't read NVMC_READY register");
+			return res;
+		}
+
+		if (ready == NRF52_NVMC_READY)
+			return ERROR_OK;
+
+		alive_sleep(1);
+	} while (timeout--);
+
+	LOG_DEBUG("Timed out waiting for the NVMC to be ready");
+	return ERROR_FLASH_BUSY;
+}
+
+static int nrf52_nvmc_erase_enable(struct nrf52_info *chip)
+{
+	int res;
+
+	res = nrf52_wait_for_nvmc(chip);
+	if (res != ERROR_OK)
+		return res;
+
+	res = target_write_u32(chip->target,
+						NRF52_NVMC_CONFIG_ADDR,
+						NRF52_NVMC_CONFIG_EEN);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Failed to configure the NVMC for erasing");
+		return res;
+	}
+
+	return res;
+}
+
+static int nrf52_nvmc_write_enable(struct nrf52_info *chip)
+{
+	int res;
+
+	res = nrf52_wait_for_nvmc(chip);
+	if (res != ERROR_OK)
+		return res;
+
+	res = target_write_u32(chip->target,
+						NRF52_NVMC_CONFIG_ADDR,
+						NRF52_NVMC_CONFIG_WEN);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Failed to configure the NVMC for writing");
+		return res;
+	}
+
+	return res;
+}
+
+static int nrf52_nvmc_read_only(struct nrf52_info *chip)
+{
+	int res;
+
+	res = nrf52_wait_for_nvmc(chip);
+	if (res != ERROR_OK)
+		return res;
+
+	res = target_write_u32(chip->target,
+						NRF52_NVMC_CONFIG_ADDR,
+						NRF52_NVMC_CONFIG_REN);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Failed to configure the NVMC for read-only");
+		return res;
+	}
+
+	return res;
+}
+
+static int nrf52_nvmc_generic_erase(struct nrf52_info *chip,
+								uint32_t erase_register,
+								uint32_t erase_value)
+{
+	int res;
+
+	res = nrf52_nvmc_erase_enable(chip);
+	if (res != ERROR_OK)
+		return res;
+
+	res = target_write_u32(chip->target,
+						erase_register,
+						erase_value);
+	if (res != ERROR_OK)
+		LOG_ERROR("Failed to write NVMC erase register");
+
+	return nrf52_nvmc_read_only(chip);
+}
+
+static int nrf52_protect_check(struct flash_bank *bank)
+{
+	LOG_WARNING("nrf52_protect_check() is not implemented for nRF52 series devices yet");
+	return ERROR_OK;
+}
+
+static int nrf52_protect(struct flash_bank *bank, int set, int first, int last)
+{
+	LOG_WARNING("nrf52_protect() is not implemented for nRF52 series devices yet");
+	return ERROR_OK;
+}
+
+static struct flash_sector *nrf52_find_sector_by_address(struct flash_bank *bank, uint32_t address)
+{
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	for (int i = 0; i < bank->num_sectors; i++)
+		if (bank->sectors[i].offset <= address &&
+			address < (bank->sectors[i].offset + chip->code_page_size)) {
+			return &bank->sectors[i];
+		}
+
+	return NULL;
+}
+
+static int nrf52_erase_all(struct nrf52_info *chip)
+{
+	LOG_DEBUG("Erasing all non-volatile memory");
+	return nrf52_nvmc_generic_erase(chip,
+								NRF52_NVMC_ERASEALL_ADDR,
+								0x01);
+}
+
+static int nrf52_erase_page(struct flash_bank *bank,
+							struct nrf52_info *chip,
+							struct flash_sector *sector)
+{
+	int res;
+
+	LOG_DEBUG("Erasing page at 0x%"PRIx32, sector->offset);
+	if (sector->is_protected == 1) {
+		LOG_ERROR("Cannot erase protected sector at 0x%" PRIx32, sector->offset);
+		return ERROR_FAIL;
+	}
+
+	if (bank->base == NRF52_UICR_BASE_ADDR) {
+		res = nrf52_nvmc_generic_erase(chip,
+									NRF52_NVMC_ERASEUICR_ADDR,
+									0x00000001);
+	} else {
+		res = nrf52_nvmc_generic_erase(chip,
+									NRF52_NVMC_ERASEPAGE_ADDR,
+									sector->offset);
+	}
+
+	if (res == ERROR_OK)
+		sector->is_erased = 1;
+	return res;
+}
+
+static const uint8_t nrf52_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 nrf52_ll_flash_write(struct nrf52_info *chip, uint32_t offset, const uint8_t *buffer, uint32_t bytes)
+{
+	struct target *target = chip->target;
+	uint32_t buffer_size = 8192;
+	struct working_area *write_algorithm;
+	struct working_area *source;
+	uint32_t address = NRF52_FLASH_BASE_ADDR + offset;
+	struct reg_param reg_params[4];
+	struct armv7m_algorithm armv7m_info;
+	int retval = ERROR_OK;
+
+	LOG_DEBUG("Writing buffer to flash offset=0x%"PRIx32" bytes=0x%"PRIx32, offset, bytes);
+	assert(bytes % 4 == 0);
+
+	/* allocate working area with flash programming code */
+	if (target_alloc_working_area(target, sizeof(nrf52_flash_write_code),
+			&write_algorithm) != ERROR_OK) {
+		LOG_WARNING("no working area available, falling back to slow memory writes");
+
+		for (; bytes > 0; bytes -= 4) {
+			retval = target_write_memory(chip->target,
+										offset, 4, 1, buffer);
+			if (retval != ERROR_OK)
+				return retval;
+
+			retval = nrf52_wait_for_nvmc(chip);
+			if (retval != ERROR_OK)
+				return retval;
+
+			offset += 4;
+			buffer += 4;
+		}
+
+		return ERROR_OK;
+	}
+
+	LOG_WARNING("using fast async flash loader. This is currently supported");
+	LOG_WARNING("only with ST-Link and CMSIS-DAP. If you have issues, add");
+	LOG_WARNING("\"set WORKAREASIZE 0\" before sourcing nrf52.cfg to disable it");
+
+	retval = target_write_buffer(target, write_algorithm->address,
+				sizeof(nrf52_flash_write_code),
+				nrf52_flash_write_code);
+	if (retval != ERROR_OK)
+		return retval;
+
+	/* memory buffer */
+	while (target_alloc_working_area(target, buffer_size, &source) != ERROR_OK) {
+		buffer_size /= 2;
+		buffer_size &= ~3UL; /* Make sure it's 4 byte aligned */
+		if (buffer_size <= 256) {
+			/* free working area, write algorithm already allocated */
+			target_free_working_area(target, write_algorithm);
+
+			LOG_WARNING("No large enough working area available, can't do block memory writes");
+			return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
+		}
+	}
+
+	armv7m_info.common_magic = ARMV7M_COMMON_MAGIC;
+	armv7m_info.core_mode = ARM_MODE_THREAD;
+
+	init_reg_param(&reg_params[0], "r0", 32, PARAM_IN_OUT);	/* byte count */
+	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 */
+
+	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);
+
+	retval = target_run_flash_async_algorithm(target, buffer, bytes/4, 4,
+			0, NULL,
+			4, reg_params,
+			source->address, source->size,
+			write_algorithm->address, 0,
+			&armv7m_info);
+
+	target_free_working_area(target, source);
+	target_free_working_area(target, write_algorithm);
+
+	destroy_reg_param(&reg_params[0]);
+	destroy_reg_param(&reg_params[1]);
+	destroy_reg_param(&reg_params[2]);
+	destroy_reg_param(&reg_params[3]);
+
+	return retval;
+}
+
+/* Check and erase flash sectors in specified range, then start a low level page write.
+   start/end must be sector aligned.
+*/
+static int nrf52_write_pages(struct flash_bank *bank, uint32_t start, uint32_t end, const uint8_t *buffer)
+{
+	int res;
+	uint32_t offset;
+	struct flash_sector *sector;
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	assert(start % chip->code_page_size == 0);
+	assert(end % chip->code_page_size == 0);
+
+	/* Erase all sectors */
+	for (offset = start; offset < end; offset += chip->code_page_size) {
+		sector = nrf52_find_sector_by_address(bank, offset);
+
+		if (sector == NULL) {
+			LOG_ERROR("Invalid sector @ 0x%08"PRIx32, offset);
+			return ERROR_FLASH_SECTOR_INVALID;
+		}
+
+		if (sector->is_protected == 1) {
+			LOG_ERROR("Can't erase protected sector @ 0x%08"PRIx32, offset);
+			return ERROR_FAIL;
+		}
+
+		if (sector->is_erased != 1) {	/* 1 = erased, 0= not erased, -1 = unknown */
+			res = nrf52_erase_page(bank, chip, sector);
+			if (res != ERROR_OK) {
+				LOG_ERROR("Failed to erase sector @ 0x%08"PRIx32, sector->offset);
+				return res;
+			}
+		}
+		sector->is_erased = 1;
+	}
+
+	res = nrf52_nvmc_write_enable(chip);
+	if (res != ERROR_OK)
+		return res;
+
+	res = nrf52_ll_flash_write(chip, start, buffer, (end - start));
+	if (res != ERROR_OK) {
+		LOG_ERROR("Failed to write FLASH");
+		nrf52_nvmc_read_only(chip);
+		return res;
+	}
+
+	return nrf52_nvmc_read_only(chip);
+}
+
+static int nrf52_erase(struct flash_bank *bank, int first, int last)
+{
+	int res = ERROR_OK;
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	/* For each sector to be erased */
+	for (int s = first; s <= last && res == ERROR_OK; s++)
+		res = nrf52_erase_page(bank, chip, &bank->sectors[s]);
+
+	return res;
+}
+
+static int nrf52_code_flash_write(struct flash_bank *bank,
+								struct nrf52_info *chip,
+								const uint8_t *buffer, uint32_t offset, uint32_t count)
+{
+	int res;
+	/* Need to perform reads to fill any gaps we need to preserve in the first page,
+	   before the start of buffer, or in the last page, after the end of buffer */
+	uint32_t first_page = offset / chip->code_page_size;
+	uint32_t last_page = DIV_ROUND_UP(offset+count, chip->code_page_size);
+
+	uint32_t first_page_offset = first_page * chip->code_page_size;
+	uint32_t last_page_offset = last_page * chip->code_page_size;
+
+	LOG_DEBUG("Padding write from 0x%08"PRIx32"-0x%08"PRIx32" as 0x%08"PRIx32"-0x%08"PRIx32,
+			offset, offset+count, first_page_offset, last_page_offset);
+
+	uint32_t page_cnt = last_page - first_page;
+	uint8_t buffer_to_flash[page_cnt * chip->code_page_size];
+
+	/* Fill in any space between start of first page and start of buffer */
+	uint32_t pre = offset - first_page_offset;
+	if (pre > 0) {
+		res = target_read_memory(bank->target, first_page_offset, 1, pre, buffer_to_flash);
+		if (res != ERROR_OK)
+			return res;
+	}
+
+	/* Fill in main contents of buffer */
+	memcpy(buffer_to_flash + pre, buffer, count);
+
+	/* Fill in any space between end of buffer and end of last page */
+	uint32_t post = last_page_offset - (offset + count);
+	if (post > 0) {
+		/* Retrieve the full row contents from Flash */
+		res = target_read_memory(bank->target, offset + count, 1, post, buffer_to_flash + pre + count);
+		if (res != ERROR_OK)
+			return res;
+	}
+
+	return nrf52_write_pages(bank, first_page_offset, last_page_offset, buffer_to_flash);
+}
+
+static int nrf52_uicr_flash_write(struct flash_bank *bank,
+								struct nrf52_info *chip,
+								const uint8_t *buffer, uint32_t offset, uint32_t count)
+{
+	int res;
+	uint32_t nrf52_uicr_size = chip->code_page_size;
+	uint8_t uicr[nrf52_uicr_size];
+	struct flash_sector *sector = &bank->sectors[0];
+
+	if ((offset + count) > nrf52_uicr_size)
+		return ERROR_FAIL;
+
+	res = target_read_memory(bank->target, NRF52_UICR_BASE_ADDR, 1, nrf52_uicr_size, uicr);
+
+	if (res != ERROR_OK)
+		return res;
+
+	if (sector->is_erased != 1) {
+		res = nrf52_erase_page(bank, chip, sector);
+		if (res != ERROR_OK)
+			return res;
+	}
+
+	memcpy(&uicr[offset], buffer, count);
+
+	res = nrf52_nvmc_write_enable(chip);
+	if (res != ERROR_OK)
+		return res;
+
+	res = nrf52_ll_flash_write(chip, NRF52_UICR_BASE_ADDR, uicr, nrf52_uicr_size);
+	if (res != ERROR_OK) {
+		nrf52_nvmc_read_only(chip);
+		return res;
+	}
+
+	return nrf52_nvmc_read_only(chip);
+}
+
+
+static int nrf52_write(struct flash_bank *bank, const uint8_t *buffer,
+					uint32_t offset, uint32_t count)
+{
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	return chip->bank[bank->bank_number].write(bank, chip, buffer, offset, count);
+}
+
+
+FLASH_BANK_COMMAND_HANDLER(nrf52_flash_bank_command)
+{
+	static struct nrf52_info *chip;
+
+	assert(bank != NULL);
+
+	switch (bank->base) {
+	case NRF52_FLASH_BASE_ADDR:
+		bank->bank_number = 0;
+		break;
+	case NRF52_UICR_BASE_ADDR:
+		bank->bank_number = 1;
+		break;
+	default:
+		LOG_ERROR("Invalid bank address 0x%08" PRIx32, bank->base);
+		return ERROR_FAIL;
+	}
+
+	if (!chip) {
+		/* Create a new chip */
+		chip = calloc(1, sizeof(*chip));
+		assert(chip != NULL);
+
+		chip->target = bank->target;
+	}
+
+	switch (bank->base) {
+	case NRF52_FLASH_BASE_ADDR:
+		chip->bank[bank->bank_number].write = nrf52_code_flash_write;
+		break;
+	case NRF52_UICR_BASE_ADDR:
+		chip->bank[bank->bank_number].write = nrf52_uicr_flash_write;
+		break;
+	}
+
+	chip->bank[bank->bank_number].probed = false;
+	bank->driver_priv = chip;
+
+	return ERROR_OK;
+}
+
+COMMAND_HANDLER(nrf52_handle_mass_erase_command)
+{
+	int res;
+	struct flash_bank *bank = NULL;
+	struct target *target = get_current_target(CMD_CTX);
+
+	res = get_flash_bank_by_addr(target, NRF52_FLASH_BASE_ADDR, true, &bank);
+	if (res != ERROR_OK)
+		return res;
+
+	assert(bank != NULL);
+
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	res = nrf52_erase_all(chip);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Failed to erase the chip");
+		nrf52_protect_check(bank);
+		return res;
+	}
+
+	for (int i = 0; i < bank->num_sectors; i++)
+		bank->sectors[i].is_erased = 1;
+
+	res = nrf52_protect_check(bank);
+	if (res != ERROR_OK) {
+		LOG_ERROR("Failed to check chip's write protection");
+		return res;
+	}
+
+	res = get_flash_bank_by_addr(target, NRF52_UICR_BASE_ADDR, true, &bank);
+	if (res != ERROR_OK)
+		return res;
+
+	bank->sectors[0].is_erased = 1;
+
+	return ERROR_OK;
+}
+
+static int nrf52_info(struct flash_bank *bank, char *buf, int buf_size)
+{
+	int res;
+	uint32_t ficr[2];
+	struct nrf52_info *chip = bank->driver_priv;
+	assert(chip != NULL);
+
+	res = target_read_u32(chip->target, NRF52_FICR_CODEPAGESIZE_ADDR, &ficr[0]);
+		if (res != ERROR_OK) {
+			LOG_ERROR("Couldn't read NVMC_READY register");
+			return res;
+		}
+
+	res = target_read_u32(chip->target, NRF52_FICR_CODESIZE_ADDR, &ficr[1]);
+		if (res != ERROR_OK) {
+			LOG_ERROR("Couldn't read NVMC_READY register");
+			return res;
+		}
+
+	snprintf(buf, buf_size,
+			"\n--------nRF52 Series Device--------\n\n"
+			"\n[factory information control block]\n"
+			"code page size: %"PRIu32"B\n"
+			"code memory size: %"PRIu32"kB\n",
+			ficr[0],
+			(ficr[1] * ficr[0]) / 1024);
+
+	return ERROR_OK;
+}
+
+static const struct command_registration nrf52_exec_command_handlers[] = {
+	{
+		.name		= "mass_erase",
+		.handler	= nrf52_handle_mass_erase_command,
+		.mode		= COMMAND_EXEC,
+		.help		= "Erase all flash contents of the chip.",
+	},
+	COMMAND_REGISTRATION_DONE
+};
+
+static const struct command_registration nrf52_command_handlers[] = {
+	{
+		.name	= "nrf52",
+		.mode	= COMMAND_ANY,
+		.help	= "nrf52 flash command group",
+		.usage	= "",
+		.chain	= nrf52_exec_command_handlers,
+	},
+	COMMAND_REGISTRATION_DONE
+};
+
+struct flash_driver nrf52_flash = {
+	.name			= "nrf52",
+	.commands		= nrf52_command_handlers,
+	.flash_bank_command	= nrf52_flash_bank_command,
+	.info			= nrf52_info,
+	.erase			= nrf52_erase,
+	.protect		= nrf52_protect,
+	.write			= nrf52_write,
+	.read			= default_flash_read,
+	.probe			= nrf52_probe,
+	.auto_probe		= nrf52_auto_probe,
+	.erase_check	= default_flash_blank_check,
+	.protect_check	= nrf52_protect_check,
+};
diff --git a/tcl/target/nrf52.cfg b/tcl/target/nrf52.cfg
index c1cbf1a..41a22ff 100644
--- a/tcl/target/nrf52.cfg
+++ b/tcl/target/nrf52.cfg
@@ -10,6 +10,13 @@ if { [info exists CHIPNAME] } {
 	set _CHIPNAME nrf52
 }
 
+# Work-area is a space in RAM used for flash programming, by default use 16kB.
+if { [info exists WORKAREASIZE] } {
+        set _WORKAREASIZE $WORKAREASIZE
+} else {
+        set _WORKAREASIZE 0x4000
+}
+
 if { [info exists CPUTAPID] } {
 	set _CPUTAPID $CPUTAPID
 } else {
@@ -22,7 +29,15 @@ set _TARGETNAME $_CHIPNAME.cpu
 target create $_TARGETNAME cortex_m -chain-position $_TARGETNAME
 
 adapter_khz 10000
+$_TARGETNAME configure -work-area-phys 0x20000000 -work-area-size $_WORKAREASIZE -work-area-backup 0
 
 if { ![using_hla] } {
 	cortex_m reset_config sysresetreq
 }
+
+flash bank $_CHIPNAME.flash nrf52 0x00000000 0 1 1 $_TARGETNAME
+flash bank $_CHIPNAME.uicr nrf52 0x10001000 0 1 1 $_TARGETNAME
+
+adapter_khz 1000
+
+$_TARGETNAME configure -event reset-end {}
