target/xtensa: avoid IHI for writes to non-executable memory

[openocd.git] / src / flash / nor / qn908x.c

// SPDX-License-Identifier: GPL-2.0-or-later
/***************************************************************************
 *   Copyright (C) 2020 iosabi                                             *
 *   iosabi <iosabi@protonmail.com>                                        *
 ***************************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "imp.h"

#include <helper/binarybuffer.h>
#include <helper/bits.h>
#include <helper/crc32.h>
#include <helper/time_support.h>
#include <helper/types.h>

/* The QN908x has two flash regions, one is the main flash region holding the
 * user code and the second one is a small (0x800 bytes) "Flash information
 * page" that can't be written to by the user. This page contains information
 * programmed at the factory.
 *
 * The main flash region is normally 512 KiB, there's a field in the "Flash
 * information page" that allows to specify for 256 KiB size chips. However, at
 * the time of writing, none of the variants in the market have 256 KiB.
 *
 * The flash is divided into blocks of 256 KiB each, therefore containing two
 * blocks. A block is subdivided into pages, of 2048 bytes. A page is the
 * smallest region that can be erased or protected independently, although it
 * is also possible to erase a whole block or both blocks. A page is subdivided
 * into 8 rows of 64 words (32-bit words). The word subdivision is only
 * relevant because DMA can write multiple words in the same row in the same
 * flash program operation.
 *
 * For the Flash information page we are only interested in the last
 * 0x100 bytes which contain a CRC-32 checksum of that 0x100 bytes long region
 * and a field stating the size of the flash. This is also a good check that
 * we are dealing with the right chip/flash configuration and is used in the
 * probe() function.
 */
#define QN908X_FLASH_BASE                                               0x01000000

#define QN908X_FLASH_PAGE_SIZE                                  2048
#define QN908X_FLASH_PAGES_PER_BLOCK                    128
#define QN908X_FLASH_MAX_BLOCKS                                 2
#define QN908X_FLASH_BLOCK_SIZE \
                (QN908X_FLASH_PAGES_PER_BLOCK * QN908X_FLASH_PAGE_SIZE)
#define QN908X_FLASH_IRQ_VECTOR_CHECKSUM_POS    0x1c
#define QN908X_FLASH_IRQ_VECTOR_CHECKSUM_SIZE   4
#define QN908X_FLASH_IRQ_VECTOR_CHECKSUM_END    \
        (QN908X_FLASH_IRQ_VECTOR_CHECKSUM_POS + QN908X_FLASH_IRQ_VECTOR_CHECKSUM_SIZE)


/* Flash information page memory fields. */
#define QN908X_INFO_PAGE_BASE                                   0x210b0000u
#define QN908X_INFO_PAGE_CRC32                                  (QN908X_INFO_PAGE_BASE + 0x700)
#define QN908X_INFO_PAGE_CRC_START                              (QN908X_INFO_PAGE_BASE + 0x704)
#define QN908X_INFO_PAGE_BOOTLOADER_VER                 (QN908X_INFO_PAGE_BASE + 0x704)
#define QN908X_INFO_PAGE_FLASH_SIZE                             (QN908X_INFO_PAGE_BASE + 0x708)
#define QN908X_INFO_PAGE_BLUETOOTH_ADDR                 (QN908X_INFO_PAGE_BASE + 0x7fa)
#define QN908X_INFO_PAGE_CRC_END                                (QN908X_INFO_PAGE_BASE + 0x800)


/* Possible values of the QN908X_INFO_PAGE_FLASH_SIZE field. */
enum qn908x_info_page_flash_size {
        QN908X_FLASH_SIZE_512K                                  = 0xfffff0ff,
        QN908X_FLASH_SIZE_256K                                  = 0xffffe0ff,
};

/* QN908x "Flash memory controller", described in section 28 of the user
 * manual. In the NXP SDK this peripheral is called "FLASH", however we use the
 * name "FMC" (Flash Memory Controller) here when referring to the controller
 * to avoid confusion with other "flash" terms in OpenOCD. */
#define QN908X_FMC_BASE 0x40081000u
#define QN908X_FMC_INI_RD_EN                                            (QN908X_FMC_BASE + 0x00)
#define QN908X_FMC_ERASE_CTRL                                           (QN908X_FMC_BASE + 0x04)
#define QN908X_FMC_ERASE_TIME                                           (QN908X_FMC_BASE + 0x08)
#define QN908X_FMC_TIME_CTRL                                            (QN908X_FMC_BASE + 0x0c)
#define QN908X_FMC_SMART_CTRL                                           (QN908X_FMC_BASE + 0x10)
#define QN908X_FMC_INT_STAT                                                     (QN908X_FMC_BASE + 0x18)
#define QN908X_FMC_LOCK_STAT_0                                          (QN908X_FMC_BASE + 0x20)
#define QN908X_FMC_LOCK_STAT_1                                          (QN908X_FMC_BASE + 0x24)
#define QN908X_FMC_LOCK_STAT_2                                          (QN908X_FMC_BASE + 0x28)
#define QN908X_FMC_LOCK_STAT_3                                          (QN908X_FMC_BASE + 0x2c)
#define QN908X_FMC_LOCK_STAT_4                                          (QN908X_FMC_BASE + 0x30)
#define QN908X_FMC_LOCK_STAT_5                                          (QN908X_FMC_BASE + 0x34)
#define QN908X_FMC_LOCK_STAT_6                                          (QN908X_FMC_BASE + 0x38)
#define QN908X_FMC_LOCK_STAT_7                                          (QN908X_FMC_BASE + 0x3c)
#define QN908X_FMC_LOCK_STAT_8                                          (QN908X_FMC_BASE + 0x40)
#define QN908X_FMC_STATUS1                                                      (QN908X_FMC_BASE + 0x48)
#define QN908X_FMC_DEBUG_PASSWORD                                       (QN908X_FMC_BASE + 0xa8)
#define QN908X_FMC_ERASE_PASSWORD                                       (QN908X_FMC_BASE + 0xac)

#define QN908X_FMC_INI_RD_EN_INI_RD_EN_MASK                     BIT(0)

#define QN908X_FMC_STATUS1_FSH_ERA_BUSY_L_MASK          BIT(9)
#define QN908X_FMC_STATUS1_FSH_WR_BUSY_L_MASK           BIT(10)
#define QN908X_FMC_STATUS1_FSH_ERA_BUSY_H_MASK          BIT(12)
#define QN908X_FMC_STATUS1_FSH_WR_BUSY_H_MASK           BIT(13)
#define QN908X_FMC_STATUS1_INI_RD_DONE_MASK                     BIT(15)
#define QN908X_FMC_STATUS1_FSH_STA_MASK                         BIT(26)

#define QN908X_FMC_ERASE_CTRL_PAGE_IDXL_SHIFT           0
#define QN908X_FMC_ERASE_CTRL_PAGE_IDXH_SHIFT           8
#define QN908X_FMC_ERASE_CTRL_HALF_ERASEL_EN_SHIFT      28
#define QN908X_FMC_ERASE_CTRL_HALF_ERASEH_EN_SHIFT      29
#define QN908X_FMC_ERASE_CTRL_PAGE_ERASEL_EN_SHIFT      30
#define QN908X_FMC_ERASE_CTRL_PAGE_ERASEH_EN_SHIFT      31

#define QN908X_FMC_INT_STAT_AHBL_INT_MASK                       BIT(0)
#define QN908X_FMC_INT_STAT_LOCKL_INT_MASK                      BIT(1)
#define QN908X_FMC_INT_STAT_ERASEL_INT_MASK                     BIT(2)
#define QN908X_FMC_INT_STAT_WRITEL_INT_MASK                     BIT(3)
#define QN908X_FMC_INT_STAT_WR_BUFL_INT_MASK            BIT(4)
#define QN908X_FMC_INT_STAT_WRITE_FAIL_L_INT_MASK       BIT(5)
#define QN908X_FMC_INT_STAT_ERASE_FAIL_L_INT_MASK       BIT(6)
#define QN908X_FMC_INT_STAT_AHBH_INT_MASK                       BIT(8)
#define QN908X_FMC_INT_STAT_LOCKH_INT_MASK                      BIT(9)
#define QN908X_FMC_INT_STAT_ERASEH_INT_MASK                     BIT(10)
#define QN908X_FMC_INT_STAT_WRITEH_INT_MASK                     BIT(11)
#define QN908X_FMC_INT_STAT_WR_BUFH_INT_MASK            BIT(12)
#define QN908X_FMC_INT_STAT_WRITE_FAIL_H_INT_MASK       BIT(13)
#define QN908X_FMC_INT_STAT_ERASE_FAIL_H_INT_MASK       BIT(14)

#define QN908X_FMC_SMART_CTRL_PRGML_EN_MASK                     BIT(0)
#define QN908X_FMC_SMART_CTRL_PRGMH_EN_MASK                     BIT(1)
#define QN908X_FMC_SMART_CTRL_SMART_WRITEL_EN_MASK      BIT(2)
#define QN908X_FMC_SMART_CTRL_SMART_WRITEH_EN_MASK      BIT(3)
#define QN908X_FMC_SMART_CTRL_SMART_ERASEL_EN_MASK      BIT(4)
#define QN908X_FMC_SMART_CTRL_SMART_ERASEH_EN_MASK      BIT(5)
#define QN908X_FMC_SMART_CTRL_MAX_WRITE_MASK            0xf00u
#define QN908X_FMC_SMART_CTRL_MAX_WRITE_SHIFT           8u
#define QN908X_FMC_SMART_CTRL_MAX_WRITE(x) \
        (((uint32_t)(((uint32_t)(x)) << QN908X_FMC_SMART_CTRL_MAX_WRITE_SHIFT)) \
        & QN908X_FMC_SMART_CTRL_MAX_WRITE_MASK)
#define QN908X_FMC_SMART_CTRL_MAX_ERASE_MASK            0x3f000u
#define QN908X_FMC_SMART_CTRL_MAX_ERASE_SHIFT           12u
#define QN908X_FMC_SMART_CTRL_MAX_ERASE(x) \
        (((uint32_t)(((uint32_t)(x)) << QN908X_FMC_SMART_CTRL_MAX_ERASE_SHIFT)) \
        & QN908X_FMC_SMART_CTRL_MAX_ERASE_MASK)

#define QN908X_FMC_SMART_CTRL_MAX_ERASE_RETRIES         9
#define QN908X_FMC_SMART_CTRL_MAX_WRITE_RETRIES         9

#define QN908X_FMC_TIME_CTRL_PRGM_CYCLE_MASK            0xfffu
#define QN908X_FMC_TIME_CTRL_PRGM_CYCLE_SHIFT           0u
#define QN908X_FMC_TIME_CTRL_PRGM_CYCLE(x) \
        (((uint32_t)(((uint32_t)(x)) << QN908X_FMC_TIME_CTRL_PRGM_CYCLE_SHIFT)) \
        & QN908X_FMC_TIME_CTRL_PRGM_CYCLE_MASK)
#define QN908X_FMC_TIME_CTRL_TIME_BASE_MASK                     0xff000u
#define QN908X_FMC_TIME_CTRL_TIME_BASE_SHIFT            12u
#define QN908X_FMC_TIME_CTRL_TIME_BASE(x) \
        (((uint32_t)(((uint32_t)(x)) << QN908X_FMC_TIME_CTRL_TIME_BASE_SHIFT)) \
        & QN908X_FMC_TIME_CTRL_TIME_BASE_MASK)

#define QN908X_FMC_LOCK_STAT_8_MASS_ERASE_LOCK_EN       BIT(0)
#define QN908X_FMC_LOCK_STAT_8_FSH_PROTECT_EN           BIT(1)
#define QN908X_FMC_LOCK_STAT_8_MEM_PROTECT_EN           BIT(2)
#define QN908X_FMC_LOCK_STAT_8_PROTECT_ANY                      (BIT(1) | BIT(2))

/* See Table 418 "Flash lock and protect description" in the user manual */
#define QN908X_FLASH_LOCK_ADDR                                          (QN908X_FLASH_BASE + 0x7f820)
/* Allow mass erase */
#define QN908X_FLASH_LOCK_ENABLE_MASS_ERASE                     BIT(0)
/* disallow flash access from SWD */
#define QN908X_FLASH_LOCK_ENABLE_FLASH_PROTECTION       BIT(1)
/* disallow SRAM access from SWD */
#define QN908X_FLASH_LOCK_ENABLE_MEMORY_PROTECTION      BIT(2)

/* Page lock information located at the beginning of the last page. */
struct qn908x_flash_page_lock {
        uint8_t bits[QN908X_FLASH_MAX_BLOCKS * QN908X_FLASH_PAGES_PER_BLOCK / 8];
        uint8_t protection;
        uint8_t _reserved[3];
        /* nvds_size is unused here, but we need to preserve it across erases
         * when locking and unlocking pages. */
        uint8_t nvds_size[4];
} __attribute__ ((packed));

/* Clock configuration is stored in the SYSCON. */
#define QN908X_SYSCON_BASE                                              0x40000000u
#define QN908X_SYSCON_CLK_EN                                    (QN908X_SYSCON_BASE + 0x00cu)
#define QN908X_SYSCON_CLK_CTRL                                  (QN908X_SYSCON_BASE + 0x010u)
#define QN908X_SYSCON_CHIP_ID                                   (QN908X_SYSCON_BASE + 0x108u)
#define QN908X_SYSCON_XTAL_CTRL                                 (QN908X_SYSCON_BASE + 0x180u)

/* Internal 16MHz / 8MHz clock used by the erase operation. */
#define QN908X_SYSCON_CLK_EN_CLK_DP_EN_MASK             BIT(21)

#define SYSCON_XTAL_CTRL_XTAL_DIV_MASK                  BIT(31)

#define SYSCON_CLK_CTRL_AHB_DIV_MASK                    0x1FFF0u
#define SYSCON_CLK_CTRL_AHB_DIV_SHIFT                   4u
#define SYSCON_CLK_CTRL_CLK_XTAL_SEL_MASK               BIT(19)
#define SYSCON_CLK_CTRL_CLK_OSC32M_DIV_MASK             BIT(20)
#define SYSCON_CLK_CTRL_SYS_CLK_SEL_MASK                0xC0000000u
#define SYSCON_CLK_CTRL_SYS_CLK_SEL_SHIFT               30u

#define CLOCK_16MHZ                                                             16000000u
#define CLOCK_32MHZ                                                             32000000u
#define CLOCK_32KHZ                                                             32000u

/* Watchdog block registers */
#define QN908X_WDT_BASE                                                 0x40001000u
#define QN908X_WDT_CTRL                                                 (QN908X_WDT_BASE + 0x08u)
#define QN908X_WDT_LOCK                                                 (QN908X_WDT_BASE + 0x20u)

struct qn908x_flash_bank {
        /* The number of flash blocks. Initially set to zero until the flash
         * is probed. This determines the size of the flash. */
        unsigned int num_blocks;

        unsigned int user_bank_size;
        bool calc_checksum;

        /* Whether we allow to flash an image that disables SWD access, potentially
         * bricking the device since the image can't be reflashed from SWD. */
        bool allow_swd_disabled;

        bool page_lock_loaded;
        struct qn908x_flash_page_lock page_lock;
};

/* 500 ms timeout. */
#define QN908X_DEFAULT_TIMEOUT_MS 500

/* Forward declaration of commands. */
static int qn908x_probe(struct flash_bank *bank);
static int qn908x_write(struct flash_bank *bank, const uint8_t *buffer,
                uint32_t offset, uint32_t count);

/* Update the value of a register with a mask. This helper allows to read a
 * register, modify a subset of the bits and write back the value, which is a
 * common operation when modifying only a bit filed in a register. */
static int qn908x_update_reg(struct target *target, target_addr_t reg,
                uint32_t mask, uint32_t value)
{
        uint32_t orig_value = 0;
        uint32_t new_value;
        int retval;
        if (mask != 0xffffffff) {
                /* No need to read the old value if we request a mask of 32 bits. */
                retval = target_read_u32(target, reg, &orig_value);
                if (retval != ERROR_OK) {
                        LOG_DEBUG("Error reading reg at " TARGET_ADDR_FMT
                                        ": %d", reg, retval);
                        return retval;
                }
        }
        new_value = (orig_value & ~mask) | (value & mask);
        retval = target_write_u32(target, reg, new_value);
        if (retval != ERROR_OK) {
                LOG_DEBUG("Error writing reg at " TARGET_ADDR_FMT " with 0x%08"
                                PRIx32 ": %d", reg, new_value, retval);
                return retval;
        }
        if (mask == 0xffffffff) {
                LOG_DEBUG("Updated reg at " TARGET_ADDR_FMT ": ?? -> 0x%.08"
                                PRIx32 "", reg, new_value);
        } else {
                LOG_DEBUG("Updated reg at " TARGET_ADDR_FMT ": 0x%.08" PRIx32
                                " -> 0x%.08" PRIx32, reg, orig_value, new_value);
        }
        return ERROR_OK;
}

/* Load lock bit and protection bit and load redundancy page info.
 * This populates the LOCK_STAT_n registers with the values from the lock page,
 * making protection bit changes to the last page effective. */
static int qn908x_load_lock_stat(struct target *target)
{
        int retval = target_write_u32(target, QN908X_FMC_INI_RD_EN,
                        QN908X_FMC_INI_RD_EN_INI_RD_EN_MASK);
        if (retval != ERROR_OK)
                return retval;

        uint32_t status1;
        const uint32_t status_mask = QN908X_FMC_STATUS1_FSH_STA_MASK
                        | QN908X_FMC_STATUS1_INI_RD_DONE_MASK;
        do {
                retval = target_read_u32(target, QN908X_FMC_STATUS1, &status1);
                if (retval != ERROR_OK)
                        return retval;
        } while ((status1 & status_mask) != QN908X_FMC_STATUS1_INI_RD_DONE_MASK);

        for (int i = 0; i <= 8; i++) {
                uint32_t addr = QN908X_FMC_LOCK_STAT_0 + i * 4;
                uint32_t lock_stat;
                if (target_read_u32(target, addr, &lock_stat) == ERROR_OK)
                        LOG_DEBUG("LOCK_STAT_%d = 0x%08" PRIx32, i, lock_stat);
        }
        return ERROR_OK;
}

/* Initializes the FMC controller registers for allowing writing. */
static int qn908x_init_flash(struct target *target)
{
        /* Determine the current clock configuration. */
        uint32_t clk_ctrl;
        int retval = target_read_u32(target, QN908X_SYSCON_CLK_CTRL, &clk_ctrl);
        if (retval != ERROR_OK)
                return retval;

        uint32_t clk_sel = (clk_ctrl & SYSCON_CLK_CTRL_SYS_CLK_SEL_MASK)
                        >> SYSCON_CLK_CTRL_SYS_CLK_SEL_SHIFT;
        LOG_DEBUG("Clock clk_sel=0x%08" PRIu32, clk_sel);

        /* Core clock frequency. */
        uint32_t core_freq = 0;
        switch (clk_sel) {
        case 0: /* RCO 32 MHz */
                core_freq = (clk_ctrl & SYSCON_CLK_CTRL_CLK_OSC32M_DIV_MASK) ?
                        CLOCK_16MHZ : CLOCK_32MHZ;
                break;
        case 1: /* Xin frequency */
        {
                uint32_t clk_xtal;
                retval = target_read_u32(target, QN908X_SYSCON_XTAL_CTRL, &clk_xtal);
                if (retval != ERROR_OK)
                        return retval;
                core_freq       = (clk_ctrl & SYSCON_CLK_CTRL_CLK_XTAL_SEL_MASK)
                                        && (clk_xtal & SYSCON_XTAL_CTRL_XTAL_DIV_MASK)
                                        ? CLOCK_32MHZ : CLOCK_16MHZ;
        }
        break;
        case 2: /* 32 Kz */
                core_freq = CLOCK_32KHZ;
                break;
        default:
                return ERROR_FAIL;
        }

        uint32_t ahb_div = (clk_ctrl & SYSCON_CLK_CTRL_AHB_DIV_MASK)
                        >> SYSCON_CLK_CTRL_AHB_DIV_SHIFT;
        uint32_t ahb_freq = core_freq / (ahb_div + 1);

        LOG_DEBUG("Core freq: %" PRIu32 " Hz | AHB freq: %" PRIu32 " Hz",
                        core_freq, ahb_freq);

        /* TIME_BASE is 2uS at the current AHB clock speed. */
        retval = target_write_u32(target, QN908X_FMC_TIME_CTRL,
                        QN908X_FMC_TIME_CTRL_TIME_BASE(2 * ahb_freq / 1000000) |
                        QN908X_FMC_TIME_CTRL_PRGM_CYCLE(30));
        if (retval != ERROR_OK)
                return retval;

        return qn908x_load_lock_stat(target);
}

/* flash bank qn908x <base> <size> 0 0 <target#> [calc_checksum] */
FLASH_BANK_COMMAND_HANDLER(qn908x_flash_bank_command)
{
        struct qn908x_flash_bank *qn908x_info;

        if (CMD_ARGC < 6 || CMD_ARGC > 7)
                return ERROR_COMMAND_SYNTAX_ERROR;

        if (bank->base != QN908X_FLASH_BASE) {
                LOG_ERROR("Address " TARGET_ADDR_FMT
                        " is an invalid bank address (try 0x%08" PRIx32 ")",
                        bank->base, QN908X_FLASH_BASE);
                return ERROR_COMMAND_ARGUMENT_INVALID;
        }

        qn908x_info = malloc(sizeof(struct qn908x_flash_bank));

        if (!qn908x_info)
                return ERROR_FAIL;

        bank->driver_priv = qn908x_info;
        qn908x_info->num_blocks = 0;
        qn908x_info->user_bank_size = bank->size;
        qn908x_info->page_lock_loaded = false;
        qn908x_info->allow_swd_disabled = false;

        qn908x_info->calc_checksum = false;
        if (CMD_ARGC == 7) {
                if (strcmp(CMD_ARGV[6], "calc_checksum")) {
                        free(qn908x_info);
                        return ERROR_COMMAND_ARGUMENT_INVALID;
                }
                qn908x_info->calc_checksum = true;
        }

        return ERROR_OK;
}

static int qn908x_read_page_lock(struct flash_bank *bank)
{
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;

        if (bank->target->state != TARGET_HALTED) {
                LOG_ERROR("Target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* The last page of the flash contains the "Flash lock and protect"
         * information. It is not clear where this is located on chips with only
         * one block. */
        uint32_t prot_offset = qn908x_info->num_blocks * QN908X_FLASH_BLOCK_SIZE
                        - QN908X_FLASH_PAGE_SIZE;

        int retval = target_read_memory(bank->target, bank->base + prot_offset, 4,
                        sizeof(qn908x_info->page_lock) / 4,
                        (void *)(&qn908x_info->page_lock));
        if (retval != ERROR_OK)
                return retval;
        LOG_DEBUG("Flash protection = 0x%02" PRIx8,
                        qn908x_info->page_lock.protection);

        qn908x_info->page_lock_loaded = true;
        return ERROR_OK;
}

static int qn908x_busy_check(struct target *target)
{
        uint32_t status1;
        int retval = target_read_u32(target, QN908X_FMC_STATUS1, &status1);
        if (retval != ERROR_OK)
                return retval;

        if ((status1 & (QN908X_FMC_STATUS1_FSH_ERA_BUSY_L_MASK
                                        | QN908X_FMC_STATUS1_FSH_WR_BUSY_L_MASK
                                        | QN908X_FMC_STATUS1_FSH_ERA_BUSY_H_MASK
                                        | QN908X_FMC_STATUS1_FSH_WR_BUSY_H_MASK)))
                return ERROR_FLASH_BUSY;
        return ERROR_OK;
}

static int qn908x_status_check(struct target *target)
{
        uint32_t int_stat;
        int retval = target_read_u32(target, QN908X_FMC_INT_STAT, &int_stat);
        if (retval != ERROR_OK)
                return retval;

        /* The error bits for block 0 and block 1 have the exact same layout, only
         * that block 1 error bits are shifted by 8 bits. We use this fact to
         * loop over the blocks */
        for (unsigned int block = 0; block <= 1; block++) {
                unsigned int shift = (block) ? 8 : 0;
                if (int_stat & (QN908X_FMC_INT_STAT_AHBL_INT_MASK << shift)) {
                        LOG_ERROR("AHB error on block %u", block);
                        return ERROR_FAIL;
                }

                if (int_stat & (QN908X_FMC_INT_STAT_LOCKL_INT_MASK << shift)) {
                        LOG_ERROR("Locked page being accessed error on block %u", block);
                        return ERROR_FAIL;
                }

                if (int_stat & (QN908X_FMC_INT_STAT_WRITE_FAIL_L_INT_MASK << shift)) {
                        LOG_ERROR("Smart write on block %u failed", block);
                        return ERROR_FAIL;
                }

                if ((int_stat & (QN908X_FMC_INT_STAT_ERASE_FAIL_L_INT_MASK << shift))
                                || (int_stat & (QN908X_FMC_INT_STAT_ERASE_FAIL_H_INT_MASK << shift))) {
                        LOG_ERROR("Smart erase on block %u failed", block);
                        return ERROR_FAIL;
                }
        }

        return ERROR_OK;
}

static int qn908x_wait_for_idle(struct target *target, int64_t timeout_ms)
{
        int64_t ms_start = timeval_ms();

        int busy = ERROR_FLASH_BUSY;
        while (busy != ERROR_OK) {
                busy = qn908x_busy_check(target);
                if (busy != ERROR_OK && busy != ERROR_FLASH_BUSY)
                        return busy;
                if (timeval_ms() - ms_start > timeout_ms) {
                        LOG_ERROR("Timeout waiting to be idle.");
                        return ERROR_TIMEOUT_REACHED;
                }
        }
        return ERROR_OK;
}

/* Set up the chip to perform an erase (page or block) operation. */
static int qn908x_setup_erase(struct target *target)
{
        int retval;
        if (target->state != TARGET_HALTED) {
                LOG_ERROR("Target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* Enable 8MHz clock. */
        retval = qn908x_update_reg(target, QN908X_SYSCON_CLK_EN,
                        QN908X_SYSCON_CLK_EN_CLK_DP_EN_MASK,
                        QN908X_SYSCON_CLK_EN_CLK_DP_EN_MASK);
        if (retval != ERROR_OK)
                return retval;

        /* Set ERASE_TIME to 2ms for smart erase. */
        retval = qn908x_update_reg(target, QN908X_FMC_ERASE_TIME,
                        (1u << 20) - 1,
                        2000 * 8);      /* 2000 uS * 8 MHz = x cycles */
        if (retval != ERROR_OK)
                return retval;

        /* Set up smart erase. SWD can only perform smart erase. */
        uint32_t ctrl_val       = QN908X_FMC_SMART_CTRL_SMART_ERASEH_EN_MASK
                                                | QN908X_FMC_SMART_CTRL_SMART_ERASEL_EN_MASK
                                                | QN908X_FMC_SMART_CTRL_MAX_ERASE(QN908X_FMC_SMART_CTRL_MAX_ERASE_RETRIES)
                                                | QN908X_FMC_SMART_CTRL_MAX_WRITE(QN908X_FMC_SMART_CTRL_MAX_WRITE_RETRIES);
        retval = target_write_u32(target, QN908X_FMC_SMART_CTRL, ctrl_val);
        if (retval != ERROR_OK)
                return retval;

        retval = qn908x_wait_for_idle(target, QN908X_DEFAULT_TIMEOUT_MS);
        if (retval != ERROR_OK)
                return retval;

        return ERROR_OK;
}

static int qn908x_erase(struct flash_bank *bank, unsigned int first,
                unsigned int last)
{
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;
        int retval = ERROR_OK;

        if (!qn908x_info->num_blocks) {
                if (qn908x_probe(bank) != ERROR_OK)
                        return ERROR_FLASH_BANK_NOT_PROBED;
        }

        retval = qn908x_setup_erase(bank->target);
        if (retval != ERROR_OK)
                return retval;

        for (unsigned int i = first; i <= last; i++) {
                if (i >= bank->num_sectors)
                        return ERROR_FLASH_SECTOR_INVALID;
                uint32_t block_idx = i / QN908X_FLASH_PAGES_PER_BLOCK;
                uint32_t page_idx = i % QN908X_FLASH_PAGES_PER_BLOCK;
                if (block_idx >= qn908x_info->num_blocks)
                        return ERROR_FLASH_SECTOR_INVALID;

                LOG_DEBUG("Erasing page %" PRIu32 " of block %" PRIu32,
                        page_idx, block_idx);

                /* Depending on the block the page we are erasing is located we
                 * need to use a different set of bits in the registers. */
                uint32_t ctrl_page_idx_shift = block_idx ?
                        QN908X_FMC_ERASE_CTRL_PAGE_IDXH_SHIFT :
                        QN908X_FMC_ERASE_CTRL_PAGE_IDXL_SHIFT;
                uint32_t ctrl_erase_en_shift = block_idx ?
                        QN908X_FMC_ERASE_CTRL_PAGE_ERASEH_EN_SHIFT :
                        QN908X_FMC_ERASE_CTRL_PAGE_ERASEL_EN_SHIFT;

                retval = target_write_u32(bank->target, QN908X_FMC_ERASE_CTRL,
                                BIT(ctrl_erase_en_shift) | (page_idx << ctrl_page_idx_shift));
                if (retval != ERROR_OK)
                        return retval;

                retval = qn908x_wait_for_idle(bank->target, QN908X_DEFAULT_TIMEOUT_MS);
                if (retval != ERROR_OK)
                        return retval;

                retval = qn908x_status_check(bank->target);
                if (retval != ERROR_OK)
                        return retval;
        }

        return retval;
}

static int qn908x_protect(struct flash_bank *bank, int set, unsigned int first,
                unsigned int last)
{
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;

        if (bank->target->state != TARGET_HALTED) {
                LOG_ERROR("Target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (!qn908x_info->page_lock_loaded) {
                int retval = qn908x_read_page_lock(bank);
                if (retval != ERROR_OK)
                        return retval;
        }

        /* Use [first, last) interval open on the right side from now on. */
        last++;
        /* We use sectors as prot_blocks. */
        bool needs_update = false;
        for (unsigned int i = first; i < last; i++) {
                if (set != (((qn908x_info->page_lock.bits[i / 8] >> (i % 8)) & 1) ^ 1))
                        needs_update = true;
        }

        /* Check that flash protection still allows SWD access to flash and RAM,
         * otherwise we won't be able to re-flash this chip from SWD unless we do a
         * mass erase. */
        if (qn908x_info->page_lock.protection & QN908X_FMC_LOCK_STAT_8_PROTECT_ANY) {
                LOG_WARNING("SWD flash/RAM access disabled in the Flash lock and "
                        "protect descriptor. You might need to issue a mass_erase to "
                        "regain SWD access to this chip after reboot.");
        }

        if (!needs_update)
                return ERROR_OK;

        int last_page = qn908x_info->num_blocks * QN908X_FLASH_PAGES_PER_BLOCK - 1;
        int retval;

        if (qn908x_info->page_lock.bits[sizeof(qn908x_info->page_lock.bits) - 1] & 0x80) {
                /* A bit 1 in the MSB in the page_lock.bits array means that the last
                 * page is unlocked, so we can just erase it. */
                retval = qn908x_erase(bank, last_page, last_page);
                if (retval != ERROR_OK)
                        return retval;
        } else {
                /* TODO: The last page is locked and we can't erase unless we use the
                 * ERASE_PASSWORD from code running on the device. For this we need to
                 * copy a little program to RAM and execute the erase command from
                 * there since there's no way to override the page protection from
                 * SWD. */
                LOG_ERROR("Unprotecting the last page is not supported. Issue a "
                        "\"qn908x mass_erase\" command to erase the whole flash, "
                        "including the last page and its protection.");
                return ERROR_FAIL;
        }

        for (unsigned int i = first / 8; i < (last + 7) / 8; i++) {
                /* first_mask contains a bit set if the bit corresponds to a block id
                 * that is larger or equal than first. This is basically 0xff in all
                 * cases except potentially the first iteration. */
                uint8_t first_mask      = (first <= i * 8)
                                                        ? 0xff : 0xff ^ ((1u << (first - i * 8)) - 1);
                /* Similar to first_mask, this contains a bit set if the corresponding
                 * is smaller than last. */
                uint8_t last_mask       = (i * 8 + 8 <= last)
                                                        ? 0xff : ((1u << (last - i * 8)) - 1);

                uint8_t mask = first_mask & last_mask;
                LOG_DEBUG("protect set=%d bits[%d] with mask=0x%02x", set, i, mask);
                /* To "set" the protection bit means to clear the bit in the page_lock
                 * bit array. */
                if (set)
                        qn908x_info->page_lock.bits[i] &= ~mask;
                else
                        qn908x_info->page_lock.bits[i] |= mask;
        }

        retval = qn908x_write(bank, (void *)(&qn908x_info->page_lock),
                        last_page * QN908X_FLASH_PAGE_SIZE, sizeof(qn908x_info->page_lock));
        if (retval != ERROR_OK)
                return retval;

        /* Reload the lock_stat to make the changes effective. */
        retval = qn908x_load_lock_stat(bank->target);
        if (retval != ERROR_OK)
                return retval;

        for (unsigned int i = first; i < last; i++)
                bank->sectors[i].is_protected = set;

        return ERROR_OK;
}

static int qn908x_write(struct flash_bank *bank, const uint8_t *buffer,
                uint32_t offset, uint32_t count)
{
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;
        int retval = ERROR_OK;

        if (bank->target->state != TARGET_HALTED) {
                LOG_ERROR("Target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* The flash infrastructure was requested to align writes to 32 bit */
        assert(((offset % 4) == 0) && ((count % 4) == 0));

        /* Compute the calc_checksum even if it wasn't requested. */
        uint32_t checksum = 0;
        if (offset == 0 && count >= 0x20) {
                for (int i = 0; i < 7; i++)
                        checksum += buf_get_u32(buffer + (i * 4), 0, 32);
                checksum = 0 - checksum;
                LOG_DEBUG("computed image checksum: 0x%8.8" PRIx32, checksum);
                uint32_t stored_checksum = buf_get_u32(buffer + 7 * 4, 0, 32);
                if (checksum != stored_checksum) {
                        LOG_WARNING("Image vector table checksum mismatch: expected 0x%08"
                                        PRIx32 " but found 0x%08" PRIx32,
                                        checksum, stored_checksum);
                        if (!qn908x_info->calc_checksum)
                                LOG_WARNING("This device will not boot, use calc_checksum in "
                                                "the flash bank.");
                        else
                                LOG_WARNING("Updating checksum, verification will fail.");
                }
        }

        /* Check the Code Read Protection (CRP) word for invalid values or not
         * allowed ones. */
        if (offset <= 0x20 && offset + count >= 0x24) {
                uint32_t crp = buf_get_u32(buffer + 0x20 - offset, 0, 32);
                /* 2-bit fields at bits 10, 12, 14, 16 and 18 must not be 00 or 11. */
                for (int i = 10; i <= 18; i += 2) {
                        uint32_t field = (crp >> i) & 3;
                        if (field == 0 || field == 3) {
                                LOG_DEBUG("Code Read Protection = 0x%08" PRIx32, crp);
                                LOG_ERROR("The Code Read Protection (CRP) field at bit %d is "
                                                "invalid (%" PRIu32 "). An invalid value could make "
                                                "the flash inaccessible.", i, field);
                                return ERROR_FAIL;
                        }
                }

                uint32_t swd_allowed = (crp >> 18) & 3;
                if (swd_allowed != 2) {
                        LOG_WARNING("The Code Read Protection (CRP) in this image "
                                        "(0x%08" PRIx32 ") is disabling the SWD access, which is "
                                        "currently used by OpenOCD to flash this device. After "
                                        "reboot, this device will not be accessible to OpenOCD "
                                        "anymore.", crp);
                        if (!qn908x_info->allow_swd_disabled) {
                                LOG_ERROR("Disabling SWD is not allowed, run "
                                                "\"qn908x allow_brick\" before if you really want to "
                                                "disable SWD. You won't be able to access this chip "
                                                "anymore from OpenOCD.");
                                return ERROR_FAIL;
                        }
                }
        }

        retval = qn908x_wait_for_idle(bank->target, QN908X_DEFAULT_TIMEOUT_MS);
        if (retval != ERROR_OK)
                return retval;

        uint32_t smart_ctrl     = QN908X_FMC_SMART_CTRL_SMART_WRITEL_EN_MASK
                                                | QN908X_FMC_SMART_CTRL_PRGML_EN_MASK
                                                | QN908X_FMC_SMART_CTRL_MAX_WRITE(QN908X_FMC_SMART_CTRL_MAX_WRITE_RETRIES);
        if (qn908x_info->num_blocks > 1) {
                smart_ctrl      |= QN908X_FMC_SMART_CTRL_SMART_WRITEH_EN_MASK
                                        | QN908X_FMC_SMART_CTRL_PRGMH_EN_MASK;
        }
        retval = target_write_u32(bank->target, QN908X_FMC_SMART_CTRL, smart_ctrl);
        if (retval != ERROR_OK)
                return retval;

        /* Write data page-wise, as suggested in the examples in section
         * 28.5.2 "Flash write" of user manual UM11023 in revision 1.1
         * (February 2018). */
        while (count > 0) {
                uint32_t next_offset = (offset & ~(QN908X_FLASH_PAGE_SIZE - 1)) + QN908X_FLASH_PAGE_SIZE;
                uint32_t chunk_len = next_offset - offset;
                if (chunk_len > count)
                        chunk_len = count;

                if (offset == 0
                                && chunk_len >= QN908X_FLASH_IRQ_VECTOR_CHECKSUM_END
                                && qn908x_info->calc_checksum) {
                        /* write data prior to checksum */
                        retval = target_write_buffer(bank->target, bank->base,
                                        QN908X_FLASH_IRQ_VECTOR_CHECKSUM_POS, buffer);
                        if (retval != ERROR_OK)
                                return retval;

                        /* write computed crc checksum instead of provided data */
                        retval = target_write_u32(bank->target, bank->base + QN908X_FLASH_IRQ_VECTOR_CHECKSUM_POS, checksum);
                        if (retval != ERROR_OK)
                                return retval;

                        retval = target_write_buffer(bank->target,
                                        bank->base + QN908X_FLASH_IRQ_VECTOR_CHECKSUM_END,
                                        chunk_len - QN908X_FLASH_IRQ_VECTOR_CHECKSUM_END,
                                        buffer + QN908X_FLASH_IRQ_VECTOR_CHECKSUM_END);
                } else {
                        retval = target_write_buffer(bank->target, bank->base + offset,
                                        chunk_len, buffer);
                }

                if (retval != ERROR_OK)
                        return retval;

                keep_alive();
                buffer += chunk_len;
                count -= chunk_len;
                offset = next_offset;

                /* Wait for FMC to complete write */
                retval = qn908x_wait_for_idle(bank->target, QN908X_DEFAULT_TIMEOUT_MS);
                if (retval != ERROR_OK)
                        return retval;

                /* Check if FMC reported any errors */
                retval = qn908x_status_check(bank->target);
                if (retval != ERROR_OK)
                        return retval;
        }

        return retval;
}

static int is_flash_protected(struct flash_bank *bank, bool *is_protected)
{
        int retval;
        uint32_t lock_stat;
        retval = target_read_u32(bank->target, QN908X_FMC_LOCK_STAT_8, &lock_stat);
        if (retval)
                return retval;

        *is_protected = false;
        if (lock_stat & QN908X_FMC_LOCK_STAT_8_PROTECT_ANY)
                *is_protected = true;

        return ERROR_OK;
}

static int qn908x_probe(struct flash_bank *bank)
{
        int retval;
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;
        uint8_t info_page[QN908X_INFO_PAGE_CRC_END - QN908X_INFO_PAGE_CRC_START];
        qn908x_info->num_blocks = 0;

        /* When the SWD access to the RAM is locked by the LOCK_STAT_8 register we
         * can't access the info page to verify the chip/bank version and it will
         * read all zeros. This situation prevents the bank from being initialized
         * at all so no other operation can be performed. The only option to
         * re-flash the chip is to perform a mass_erase from SWD, which can be
         * performed even if the mass_erase operation is locked as well.
         * We attempt to read the info page and redirect the user to perform a
         * mass_erase if we detect this situation. */
        retval = target_read_memory(bank->target, QN908X_INFO_PAGE_CRC_START,
                        sizeof(uint32_t), sizeof(info_page) / sizeof(uint32_t),
                        info_page);
        if (retval != ERROR_OK)
                return retval;

        const uint32_t crc_seed = 0xffffffff;
        /* The QN908x uses the standard little endian CRC32 polynomial and all ones
         * as seed. The CRC32 is however finalized by one last xor operation that
         * is not part of the common CRC32 implementation, so we do that by hand */
        uint32_t computed_crc = crc32_le(CRC32_POLY_LE, crc_seed,
                        info_page, sizeof(info_page));
        computed_crc ^= crc_seed;
        uint32_t read_crc;
        retval = target_read_u32(bank->target, QN908X_INFO_PAGE_CRC32, &read_crc);
        if (retval != ERROR_OK)
                return retval;

        if (computed_crc != read_crc) {
                uint32_t info_page_or = 0;
                for (unsigned int i = 0; i < sizeof(info_page); i++)
                        info_page_or |= info_page[i];
                bool is_protected;
                retval = is_flash_protected(bank, &is_protected);
                if (retval != ERROR_OK)
                        return retval;

                if (info_page_or == 0 && is_protected) {
                        LOG_ERROR("The flash or memory in this chip is protected and "
                                "cannot be accessed from the SWD interface. However, a "
                                "\"qn908x mass_erase\" can erase the device and lift this "
                                "protection.");
                        return ERROR_FAIL;
                }

                LOG_ERROR("Flash information page CRC32 mismatch, found 0x%08"
                        PRIx32 " but computed 0x%08" PRIx32 ". Flash size unknown",
                        read_crc, computed_crc);
                return ERROR_FAIL;
        }

        uint32_t flash_size_fld = target_buffer_get_u32(bank->target,
                        info_page + (QN908X_INFO_PAGE_FLASH_SIZE - QN908X_INFO_PAGE_CRC_START));

        switch (flash_size_fld) {
        case QN908X_FLASH_SIZE_512K:
                qn908x_info->num_blocks = 2;
                break;
        case QN908X_FLASH_SIZE_256K:
                qn908x_info->num_blocks = 1;
                break;
        default:
                LOG_ERROR("Unknown Flash size field: 0x%08" PRIx32,
                        flash_size_fld);
                return ERROR_FAIL;
        }

        bank->size = qn908x_info->num_blocks * QN908X_FLASH_BLOCK_SIZE;
        bank->write_start_alignment = 4;
        bank->write_end_alignment = 4;

        /* The flash supports erasing and protecting individual pages. */
        bank->num_sectors = qn908x_info->num_blocks *
                QN908X_FLASH_PAGES_PER_BLOCK;
        bank->sectors = alloc_block_array(0, QN908X_FLASH_PAGE_SIZE,
                        bank->num_sectors);
        if (!bank->sectors)
                return ERROR_FAIL;

        retval = qn908x_init_flash(bank->target);
        if (retval != ERROR_OK)
                return retval;

        LOG_INFO("Detected flash size: %d KiB", bank->size / 1024);

        return ERROR_OK;
}

static int qn908x_auto_probe(struct flash_bank *bank)
{
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;
        if (qn908x_info->num_blocks != 0)
                return ERROR_OK;
        LOG_DEBUG("auto_probe");
        return qn908x_probe(bank);
}

static int qn908x_protect_check(struct flash_bank *bank)
{
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;

        int retval = qn908x_read_page_lock(bank);
        if (retval != ERROR_OK)
                return retval;

        for (uint32_t i = 0;
                        i < qn908x_info->num_blocks * QN908X_FLASH_PAGES_PER_BLOCK;
                        i++) {
                /* A bit 0 in page_lock means page is locked. */
                bank->sectors[i].is_protected =
                        ((qn908x_info->page_lock.bits[i / 8] >> (i % 8)) & 1) ^ 1;
        }
        return ERROR_OK;
}

static int qn908x_get_info(struct flash_bank *bank,
                struct command_invocation *cmd)
{
        uint32_t bootloader_version;
        uint32_t chip_id;
        uint8_t bluetooth[6];
        int retval;
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;

        retval = target_read_u32(bank->target, QN908X_SYSCON_CHIP_ID, &chip_id);
        if (retval != ERROR_OK) {
                command_print_sameline(cmd, "Cannot read QN908x chip ID.");
                return retval;
        }
        retval = target_read_u32(bank->target, QN908X_INFO_PAGE_BOOTLOADER_VER,
                        &bootloader_version);
        if (retval != ERROR_OK) {
                command_print_sameline(cmd, "Cannot read from QN908x info page.");
                return retval;
        }

        retval = target_read_memory(bank->target, QN908X_INFO_PAGE_BLUETOOTH_ADDR,
                        1, sizeof(bluetooth), bluetooth);
        if (retval != ERROR_OK) {
                command_print_sameline(cmd, "Cannot read QN908x bluetooth L2 address.");
                return retval;
        }

        command_print_sameline(cmd, "qn908x: chip id: 0x%" PRIx32, chip_id);

        command_print_sameline(cmd, " bdaddr: "
                        "%02" PRIx8 ":%02" PRIx8 ":%02" PRIx8
                        ":%02" PRIx8 ":%02" PRIx8 ":%02" PRIx8,
                        bluetooth[0], bluetooth[1], bluetooth[2],
                        bluetooth[3], bluetooth[4], bluetooth[5]);

        command_print_sameline(cmd, " bootloader: %08" PRIx32, bootloader_version);

        command_print_sameline(cmd, " blocks: %" PRIu32, qn908x_info->num_blocks);

        return ERROR_OK;
}

COMMAND_HANDLER(qn908x_handle_allow_brick_command)
{
        int retval;

        struct target *target = get_current_target(CMD_CTX);
        struct flash_bank *bank = NULL;

        if (CMD_ARGC != 0)
                return ERROR_COMMAND_SYNTAX_ERROR;

        retval = get_flash_bank_by_addr(target, QN908X_FLASH_BASE, true, &bank);
        if (retval != ERROR_OK)
                return retval;

        /* If get_flash_bank_by_addr() did not find the flash bank, it should have
         * returned and error code instead of ERROR_OK */
        assert(bank);
        struct qn908x_flash_bank *qn908x_info = bank->driver_priv;

        LOG_WARNING("Flashing images that disable SWD in qn908x is now allowed.");
        qn908x_info->allow_swd_disabled = true;

        return ERROR_OK;
}

COMMAND_HANDLER(qn908x_handle_disable_wdog_command)
{
        int retval;
        struct target *target = get_current_target(CMD_CTX);

        if (CMD_ARGC != 0)
                return ERROR_COMMAND_SYNTAX_ERROR;

        if (target->state != TARGET_HALTED) {
                command_print(CMD, "Target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* To change any value in the watchdog block (WDT) we need to first write
         * 0x1ACCE551 to the LOCK register, and we can then set it back to any other
         * value to prevent accidental changes to the watchdog. */
        retval = target_write_u32(target, QN908X_WDT_LOCK, 0x1ACCE551);
        if (retval != ERROR_OK)
                return retval;

        retval = target_write_u32(target, QN908X_WDT_CTRL, 0);
        if (retval != ERROR_OK)
                return retval;

        return target_write_u32(target, QN908X_WDT_LOCK, 0);
}

COMMAND_HANDLER(qn908x_handle_mass_erase_command)
{
        int retval;
        bool keep_lock = false;
        if (CMD_ARGC > 1)
                return ERROR_COMMAND_SYNTAX_ERROR;
        if (CMD_ARGC == 1) {
                if (strcmp("keep_lock", CMD_ARGV[0]))
                        return ERROR_COMMAND_ARGUMENT_INVALID;
                keep_lock = true;
        }

        /* This operation can be performed without probing the bank since it is the
         * only way to unlock a chip when the flash and ram have been locked. */
        struct target *target = get_current_target(CMD_CTX);

        retval = qn908x_setup_erase(target);
        if (retval != ERROR_OK)
                return retval;

        /* Check the mass-erase locking status for information purposes only. This
         * lock applies to both the SWD and the code running in the core but can be
         * bypassed in either case. */
        uint32_t lock_stat_8;
        retval = target_read_u32(target, QN908X_FMC_LOCK_STAT_8, &lock_stat_8);
        LOG_DEBUG("LOCK_STAT_8 before erasing: 0x%" PRIx32, lock_stat_8);
        if (retval != ERROR_OK)
                return retval;
        if ((lock_stat_8 & QN908X_FMC_LOCK_STAT_8_MASS_ERASE_LOCK_EN) == 0) {
                LOG_INFO("mass_erase disabled by Flash lock and protection, forcing "
                                "mass_erase.");
        }
        /* Set the DEBUG_PASSWORD so we can force the mass erase from the SWD. We do
         * this regardless of the lock status. */
        retval = target_write_u32(target, QN908X_FMC_DEBUG_PASSWORD, 0xCA1E093F);
        if (retval != ERROR_OK)
                return retval;

        /* Erase both halves of the flash at the same time. These are actually done
         * sequentially but we need to send the command to erase both blocks since
         * doing so in a locked flash will change the LOCK_STAT_8 register to 0x01,
         * allowing us to access the (now erase) flash an memory. Erasing only one
         * block at a time does not reset the LOCK_STAT_8 register and therefore
         * will not grant access to program the chip. */
        uint32_t erase_cmd = (1u << QN908X_FMC_ERASE_CTRL_HALF_ERASEH_EN_SHIFT) |
                (1u << QN908X_FMC_ERASE_CTRL_HALF_ERASEL_EN_SHIFT);
        LOG_DEBUG("Erasing both blocks with command 0x%" PRIx32, erase_cmd);

        retval = target_write_u32(target, QN908X_FMC_ERASE_CTRL, erase_cmd);
        if (retval != ERROR_OK)
                return retval;

        retval = qn908x_wait_for_idle(target, QN908X_DEFAULT_TIMEOUT_MS);
        if (retval != ERROR_OK)
                return retval;

        retval = qn908x_status_check(target);
        if (retval != ERROR_OK)
                return retval;

        /* Set the debug password back to 0 to avoid accidental mass_erase. */
        retval = target_write_u32(target, QN908X_FMC_DEBUG_PASSWORD, 0);
        if (retval != ERROR_OK)
                return retval;

        /* At this point the flash is erased and we are able to write to the flash
         * since the LOCK_STAT_8 gets updated to 0x01 after the mass_erase. However,
         * after a hard reboot this value will be realoaded from flash which after
         * an erase is 0xff. This means that after flashing an image that doesn't
         * set the protection bits we end up with a chip that we can't debug. We
         * update this value to 0x01 unless "keep_lock" is passed to allow the SWD
         * interface to debug the flash and RAM after a hard reset. */
        if (keep_lock)
                return retval;

        retval = qn908x_init_flash(target);
        if (retval != ERROR_OK)
                return retval;

        /* Unlock access to RAM and FLASH in the last page of the flash and
         * reloading */
        retval = qn908x_wait_for_idle(target, QN908X_DEFAULT_TIMEOUT_MS);
        if (retval != ERROR_OK)
                return retval;

        uint32_t smart_ctrl = QN908X_FMC_SMART_CTRL_SMART_WRITEH_EN_MASK |
                QN908X_FMC_SMART_CTRL_PRGMH_EN_MASK;
        retval = target_write_u32(target, QN908X_FMC_SMART_CTRL, smart_ctrl);
        if (retval != ERROR_OK)
                return retval;

        retval = target_write_u32(target, QN908X_FLASH_LOCK_ADDR,
                        QN908X_FLASH_LOCK_ENABLE_MASS_ERASE);
        if (retval != ERROR_OK)
                return retval;

        retval = qn908x_wait_for_idle(target, QN908X_DEFAULT_TIMEOUT_MS);
        if (retval != ERROR_OK)
                return retval;

        /* Force a page_lock reload after the mass_erase . */
        retval = qn908x_load_lock_stat(target);
        if (retval != ERROR_OK)
                return retval;

        return retval;
}

static const struct command_registration qn908x_exec_command_handlers[] = {
        {
                .name           = "allow_brick",
                .handler        = qn908x_handle_allow_brick_command,
                .mode           = COMMAND_EXEC,
                .help           = "Allow writing images that disable SWD access in their "
                                "Code Read Protection (CRP) word. Warning: This can make your "
                                "chip inaccessible from OpenOCD or any other SWD debugger.",
                .usage          = "",
        },
        {
                .name           = "disable_wdog",
                .handler        = qn908x_handle_disable_wdog_command,
                .mode           = COMMAND_EXEC,
                .help           = "Disabled the watchdog (WDT).",
                .usage          = "",
        },
        {
                .name           = "mass_erase",
                .handler        = qn908x_handle_mass_erase_command,
                .mode           = COMMAND_EXEC,
                .help           = "Erase the whole flash chip.",
                .usage          = "[keep_lock]",
        },
        COMMAND_REGISTRATION_DONE
};

static const struct command_registration qn908x_command_handlers[] = {
        {
                .name           = "qn908x",
                .mode           = COMMAND_ANY,
                .help           = "qn908x flash controller commands",
                .usage          = "",
                .chain          = qn908x_exec_command_handlers,
        },
        COMMAND_REGISTRATION_DONE
};

const struct flash_driver qn908x_flash = {
        .name                           = "qn908x",
        .commands                       = qn908x_command_handlers,
        .flash_bank_command     = qn908x_flash_bank_command,
        .info                           = qn908x_get_info,
        .erase                          = qn908x_erase,
        .protect                        = qn908x_protect,
        .write                          = qn908x_write,
        .read                           = default_flash_read,
        .probe                          = qn908x_probe,
        .auto_probe                     = qn908x_auto_probe,
        .erase_check            = default_flash_blank_check,
        .protect_check          = qn908x_protect_check,
        .free_driver_priv       = default_flash_free_driver_priv,
};