atsame5.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 *   Copyright (C) 2017 by Tomas Vanek                     *
 *   vanekt@fbl.cz                             *
 *                                                                         *
 *   Based on at91samd.c                                                   *
 *   Copyright (C) 2013 by Andrey Yurovsky                                 *
 *   Andrey Yurovsky <yurovsky@gmail.com>                                  *
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include "imp.h"
#include "helper/binarybuffer.h"
 
#include <helper/time_support.h>
#include <jtag/jtag.h>
#include <target/cortex_m.h>
 
/* A note to prefixing.
 * Definitions and functions inherited from at91samd.c without
 * any change retained the original prefix samd_ so they eventually
 * may go to samd_common.h and .c
 * As currently there are only 3 short functions identical with
 * the original source, no common file was created. */
 
#define SAME5_PAGES_PER_BLOCK   16
#define SAME5_NUM_PROT_BLOCKS   32
#define SAMD_PAGE_SIZE_MAX  1024
 
#define SAMD_FLASH      0x00000000  /* physical Flash memory */
#define SAMD_USER_ROW       0x00804000  /* User Row of Flash */
 
#define SAME5_PAC       0x40000000  /* Peripheral Access Control */
 
#define SAMD_DSU        0x41002000  /* Device Service Unit */
#define SAMD_NVMCTRL        0x41004000  /* Non-volatile memory controller */
 
#define SAMD_DSU_STATUSA        1               /* DSU status register */
#define SAMD_DSU_DID        0x18        /* Device ID register */
#define SAMD_DSU_CTRL_EXT   0x100       /* CTRL register, external access */
 
#define SAME5_NVMCTRL_CTRLA 0x00        /* NVM control A register */
#define SAME5_NVMCTRL_CTRLB 0x04        /* NVM control B register */
#define SAMD_NVMCTRL_PARAM  0x08        /* NVM parameters register */
#define SAME5_NVMCTRL_INTFLAG   0x10        /* NVM interrupt flag register */
#define SAME5_NVMCTRL_STATUS    0x12        /* NVM status register */
#define SAME5_NVMCTRL_ADDR  0x14        /* NVM address register */
#define SAME5_NVMCTRL_LOCK  0x18        /* NVM Lock section register */
 
#define SAMD_CMDEX_KEY      0xA5UL
#define SAMD_NVM_CMD(n)     ((SAMD_CMDEX_KEY << 8) | (n & 0x7F))
 
/* NVMCTRL commands. */
#define SAME5_NVM_CMD_EP    0x00        /* Erase Page (User Page only) */
#define SAME5_NVM_CMD_EB    0x01        /* Erase Block */
#define SAME5_NVM_CMD_WP    0x03        /* Write Page */
#define SAME5_NVM_CMD_WQW   0x04        /* Write Quad Word */
#define SAME5_NVM_CMD_LR    0x11        /* Lock Region */
#define SAME5_NVM_CMD_UR    0x12        /* Unlock Region */
#define SAME5_NVM_CMD_PBC   0x15        /* Page Buffer Clear */
#define SAME5_NVM_CMD_SSB   0x16        /* Set Security Bit */
 
/* NVMCTRL bits */
#define SAME5_NVMCTRL_CTRLA_WMODE_MASK  0x30
 
#define SAME5_NVMCTRL_INTFLAG_DONE  (1 << 0)
#define SAME5_NVMCTRL_INTFLAG_ADDRE (1 << 1)
#define SAME5_NVMCTRL_INTFLAG_PROGE (1 << 2)
#define SAME5_NVMCTRL_INTFLAG_LOCKE (1 << 3)
#define SAME5_NVMCTRL_INTFLAG_ECCSE (1 << 4)
#define SAME5_NVMCTRL_INTFLAG_ECCDE (1 << 5)
#define SAME5_NVMCTRL_INTFLAG_NVME  (1 << 6)
 
 
/* Known identifiers */
#define SAMD_PROCESSOR_M0   0x01
#define SAMD_PROCESSOR_M4   0x06
#define SAMD_FAMILY_D       0x00
#define SAMD_FAMILY_E       0x03
#define SAMD_SERIES_51      0x06
#define SAME_SERIES_51      0x01
#define SAME_SERIES_53      0x03
#define SAME_SERIES_54      0x04
#define PIC32CXSG_SERIES_41 0x07
#define PIC32CXSG_SERIES_60 0x00
#define PIC32CXSG_SERIES_61 0x02
 
/* Device ID macros */
#define SAMD_GET_PROCESSOR(id) (id >> 28)
#define SAMD_GET_FAMILY(id) (((id >> 23) & 0x1F))
#define SAMD_GET_SERIES(id) (((id >> 16) & 0x3F))
#define SAMD_GET_DEVSEL(id) (id & 0xFF)
 
/* Bits to mask user row */
#define NVMUSERROW_SAM_E5_D5_MASK   0x7FFF00FF3C007FFFULL
 
struct samd_part {
    uint8_t id;
    const char *name;
    uint32_t flash_kb;
    uint32_t ram_kb;
};
 
/* See SAM D5x/E5x Family Silicon Errata and Data Sheet Clarification
 * DS80000748K */
/* Known SAMD51 parts. */
static const struct samd_part samd51_parts[] = {
    { 0x00, "SAMD51P20A", 1024, 256 },
    { 0x01, "SAMD51P19A", 512, 192 },
    { 0x02, "SAMD51N20A", 1024, 256 },
    { 0x03, "SAMD51N19A", 512, 192 },
    { 0x04, "SAMD51J20A", 1024, 256 },
    { 0x05, "SAMD51J19A", 512, 192 },
    { 0x06, "SAMD51J18A", 256, 128 },
    { 0x07, "SAMD51G19A", 512, 192 },
    { 0x08, "SAMD51G18A", 256, 128 },
};
 
/* Known SAME51 parts. */
static const struct samd_part same51_parts[] = {
    { 0x00, "SAME51N20A", 1024, 256 },
    { 0x01, "SAME51N19A", 512, 192 },
    { 0x02, "SAME51J19A", 512, 192 },
    { 0x03, "SAME51J18A", 256, 128 },
    { 0x04, "SAME51J20A", 1024, 256 },
    { 0x05, "SAME51G19A", 512, 192 },   /* New in rev D */
    { 0x06, "SAME51G18A", 256, 128 },   /* New in rev D */
};
 
/* Known SAME53 parts. */
static const struct samd_part same53_parts[] = {
    { 0x02, "SAME53N20A", 1024, 256 },
    { 0x03, "SAME53N19A", 512, 192 },
    { 0x04, "SAME53J20A", 1024, 256 },
    { 0x05, "SAME53J19A", 512, 192 },
    { 0x06, "SAME53J18A", 256, 128 },
    { 0x55, "LAN9255/ZMX020", 1024, 256 },
    { 0x56, "LAN9255/ZMX019", 512, 192 },
    { 0x57, "LAN9255/ZMX018", 256, 128 },
};
 
/* Known SAME54 parts. */
static const struct samd_part same54_parts[] = {
    { 0x00, "SAME54P20A", 1024, 256 },
    { 0x01, "SAME54P19A", 512, 192 },
    { 0x02, "SAME54N20A", 1024, 256 },
    { 0x03, "SAME54N19A", 512, 192 },
};
 
/* See PIC32CX SG41/SG60/SG61 Family Silicon Errata and Datasheet Clarifications
 * DS80000985G */
/* Known PIC32CX-SG41 parts. */
static const struct samd_part pic32cxsg41_parts[] = {
    { 0x00, "PIC32CX1025SG41128", 1024, 256 },
    { 0x01, "PIC32CX1025SG41100", 1024, 256 },
    { 0x02, "PIC32CX1025SG41064", 1024, 256 },
};
 
/* Known PIC32CX-SG60 parts. */
static const struct samd_part pic32cxsg60_parts[] = {
    { 0x00, "PIC32CX1025SG60128", 1024, 256 },
    { 0x01, "PIC32CX1025SG60100", 1024, 256 },
};
 
/* Known PIC32CX-SG61 parts. */
static const struct samd_part pic32cxsg61_parts[] = {
    { 0x00, "PIC32CX1025SG61128", 1024, 256 },
    { 0x01, "PIC32CX1025SG61100", 1024, 256 },
};
 
/* Each family of parts contains a parts table in the DEVSEL field of DID.  The
 * processor ID, family ID, and series ID are used to determine which exact
 * family this is and then we can use the corresponding table. */
struct samd_family {
    uint8_t processor;
    uint8_t family;
    uint8_t series;
    const struct samd_part *parts;
    size_t num_parts;
};
 
/* Known SAMD families */
static const struct samd_family samd_families[] = {
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_D, SAMD_SERIES_51,
        samd51_parts, ARRAY_SIZE(samd51_parts) },
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_E, SAME_SERIES_51,
        same51_parts, ARRAY_SIZE(same51_parts) },
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_E, SAME_SERIES_53,
        same53_parts, ARRAY_SIZE(same53_parts) },
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_E, SAME_SERIES_54,
        same54_parts, ARRAY_SIZE(same54_parts) },
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_E, PIC32CXSG_SERIES_41,
        pic32cxsg41_parts, ARRAY_SIZE(pic32cxsg41_parts) },
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_E, PIC32CXSG_SERIES_60,
        pic32cxsg60_parts, ARRAY_SIZE(pic32cxsg60_parts) },
    { SAMD_PROCESSOR_M4, SAMD_FAMILY_E, PIC32CXSG_SERIES_61,
        pic32cxsg61_parts, ARRAY_SIZE(pic32cxsg61_parts) },
};
 
struct samd_info {
    const struct samd_params *par;
    uint32_t page_size;
    int num_pages;
    int sector_size;
    int prot_block_size;
 
    bool probed;
    struct target *target;
};
 
 
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);
 
    for (unsigned int i = 0; i < ARRAY_SIZE(samd_families); i++) {
        if (samd_families[i].processor == processor &&
            samd_families[i].series == series &&
            samd_families[i].family == family)
            return &samd_families[i];
    }
 
    return NULL;
}
 
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)
        return NULL;
 
    for (unsigned int i = 0; i < family->num_parts; i++) {
        if (family->parts[i].id == devsel)
            return &family->parts[i];
    }
 
    return NULL;
}
 
static int same5_protect_check(struct flash_bank *bank)
{
    int res;
    uint32_t lock;
 
    res = target_read_u32(bank->target,
            SAMD_NVMCTRL + SAME5_NVMCTRL_LOCK, &lock);
    if (res != ERROR_OK)
        return res;
 
    /* Lock bits are active-low */
    for (unsigned int prot_block = 0; prot_block < bank->num_prot_blocks; prot_block++)
        bank->prot_blocks[prot_block].is_protected = !(lock & (1u<<prot_block));
 
    return ERROR_OK;
}
 
static int samd_get_flash_page_info(struct target *target,
        uint32_t *sizep, int *nump)
{
    int res;
    uint32_t param;
 
    res = target_read_u32(target, SAMD_NVMCTRL + SAMD_NVMCTRL_PARAM, &param);
    if (res == ERROR_OK) {
        /* The PSZ field (bits 18:16) indicate the page size bytes as 2^(3+n)
         * so 0 is 8KB and 7 is 1024KB. */
        if (sizep)
            *sizep = (8 << ((param >> 16) & 0x7));
        /* The NVMP field (bits 15:0) indicates the total number of pages */
        if (nump)
            *nump = param & 0xFFFF;
    } else {
        LOG_ERROR("Couldn't read NVM Parameters register");
    }
 
    return res;
}
 
static int same5_probe(struct flash_bank *bank)
{
    uint32_t id;
    int res;
    struct samd_info *chip = (struct samd_info *)bank->driver_priv;
    const struct samd_part *part;
 
    if (chip->probed)
        return ERROR_OK;
 
    res = target_read_u32(bank->target, SAMD_DSU + SAMD_DSU_DID, &id);
    if (res != ERROR_OK) {
        LOG_ERROR("Couldn't read Device ID register");
        return res;
    }
 
    part = samd_find_part(id);
    if (!part) {
        LOG_ERROR("Couldn't find part corresponding to DID %08" PRIx32, id);
        return ERROR_FAIL;
    }
 
    bank->size = part->flash_kb * 1024;
 
    res = samd_get_flash_page_info(bank->target, &chip->page_size,
            &chip->num_pages);
    if (res != ERROR_OK) {
        LOG_ERROR("Couldn't determine Flash page size");
        return res;
    }
 
    /* Sanity check: the total flash size in the DSU should match the page size
     * multiplied by the number of pages. */
    if (bank->size != chip->num_pages * chip->page_size) {
        LOG_WARNING("SAM: bank size doesn't match NVM parameters. "
                "Identified %" PRIu32 "KB Flash but NVMCTRL reports %u %" PRIu32 "B pages",
                part->flash_kb, chip->num_pages, chip->page_size);
    }
 
    /* Erase granularity = 1 block = 16 pages */
    chip->sector_size = chip->page_size * SAME5_PAGES_PER_BLOCK;
 
    /* Allocate the sector table */
    bank->num_sectors = chip->num_pages / SAME5_PAGES_PER_BLOCK;
    bank->sectors = alloc_block_array(0, chip->sector_size, bank->num_sectors);
    if (!bank->sectors)
        return ERROR_FAIL;
 
    /* 16 protection blocks per device */
    chip->prot_block_size = bank->size / SAME5_NUM_PROT_BLOCKS;
 
    /* Allocate the table of protection blocks */
    bank->num_prot_blocks = SAME5_NUM_PROT_BLOCKS;
    bank->prot_blocks = alloc_block_array(0, chip->prot_block_size, bank->num_prot_blocks);
    if (!bank->prot_blocks)
        return ERROR_FAIL;
 
    same5_protect_check(bank);
 
    /* Done */
    chip->probed = true;
 
    LOG_INFO("SAM MCU: %s (%" PRIu32 "KB Flash, %" PRIu32 "KB RAM)", part->name,
            part->flash_kb, part->ram_kb);
 
    return ERROR_OK;
}
 
static int same5_wait_and_check_error(struct target *target)
{
    int ret, ret2;
    /* Table 54-40 lists the maximum erase block time as 200 ms.
     * Include some margin.
     */
    int timeout_ms = 200 * 5;
    int64_t ts_start = timeval_ms();
    uint16_t intflag;
 
    do {
        ret = target_read_u16(target,
            SAMD_NVMCTRL + SAME5_NVMCTRL_INTFLAG, &intflag);
        if (ret != ERROR_OK) {
            LOG_ERROR("SAM: error reading the NVMCTRL_INTFLAG register");
            return ret;
        }
        if (intflag & SAME5_NVMCTRL_INTFLAG_DONE)
            break;
        keep_alive();
    } while (timeval_ms() - ts_start < timeout_ms);
 
    if (!(intflag & SAME5_NVMCTRL_INTFLAG_DONE)) {
        LOG_ERROR("SAM: NVM programming timed out");
        ret = ERROR_FLASH_OPERATION_FAILED;
    }
#if 0
    if (intflag & SAME5_NVMCTRL_INTFLAG_ECCSE)
        LOG_ERROR("SAM: ECC Single Error");
 
    if (intflag & SAME5_NVMCTRL_INTFLAG_ECCDE) {
        LOG_ERROR("SAM: ECC Double Error");
        ret = ERROR_FLASH_OPERATION_FAILED;
    }
#endif
    if (intflag & SAME5_NVMCTRL_INTFLAG_ADDRE) {
        LOG_ERROR("SAM: Addr Error");
        ret = ERROR_FLASH_OPERATION_FAILED;
    }
 
    if (intflag & SAME5_NVMCTRL_INTFLAG_NVME) {
        LOG_ERROR("SAM: NVM Error");
        ret = ERROR_FLASH_OPERATION_FAILED;
    }
 
    if (intflag & SAME5_NVMCTRL_INTFLAG_LOCKE) {
        LOG_ERROR("SAM: NVM lock error");
        ret = ERROR_FLASH_PROTECTED;
    }
 
    if (intflag & SAME5_NVMCTRL_INTFLAG_PROGE) {
        LOG_ERROR("SAM: NVM programming error");
        ret = ERROR_FLASH_OPER_UNSUPPORTED;
    }
 
    /* Clear the error conditions by writing a one to them */
    ret2 = target_write_u16(target,
            SAMD_NVMCTRL + SAME5_NVMCTRL_INTFLAG, intflag);
    if (ret2 != ERROR_OK)
        LOG_ERROR("Can't clear NVM error conditions");
 
    return ret;
}
 
static int same5_issue_nvmctrl_command(struct target *target, uint16_t cmd)
{
    int res;
 
    if (target->state != TARGET_HALTED) {
        LOG_ERROR("Target not halted");
        return ERROR_TARGET_NOT_HALTED;
    }
 
    /* Issue the NVM command */
    /* 32-bit write is used to ensure atomic operation on ST-Link */
    res = target_write_u32(target,
            SAMD_NVMCTRL + SAME5_NVMCTRL_CTRLB, SAMD_NVM_CMD(cmd));
    if (res != ERROR_OK)
        return res;
 
    /* Check to see if the NVM command resulted in an error condition. */
    return same5_wait_and_check_error(target);
}
 
static int same5_erase_block(struct target *target, uint32_t address)
{
    int res;
 
    /* Set an address contained in the block to be erased */
    res = target_write_u32(target,
            SAMD_NVMCTRL + SAME5_NVMCTRL_ADDR, address);
 
    /* Issue the Erase Block command. */
    if (res == ERROR_OK)
        res = same5_issue_nvmctrl_command(target,
                address == SAMD_USER_ROW ? SAME5_NVM_CMD_EP : SAME5_NVM_CMD_EB);
 
    if (res != ERROR_OK)  {
        LOG_ERROR("Failed to erase block containing %08" PRIx32, address);
        return ERROR_FAIL;
    }
 
    return ERROR_OK;
}
 
 
static int same5_pre_write_check(struct target *target)
{
    int res;
    uint32_t nvm_ctrla;
 
    if (target->state != TARGET_HALTED) {
        LOG_ERROR("Target not halted");
        return ERROR_TARGET_NOT_HALTED;
    }
 
    /* Check if manual write mode is set */
    res = target_read_u32(target, SAMD_NVMCTRL + SAME5_NVMCTRL_CTRLA, &nvm_ctrla);
    if (res != ERROR_OK)
        return res;
 
    if (nvm_ctrla & SAME5_NVMCTRL_CTRLA_WMODE_MASK) {
        LOG_ERROR("The flash controller must be in manual write mode. Issue 'reset init' and retry.");
        return ERROR_FAIL;
    }
 
    return res;
}
 
 
static int same5_modify_user_row_masked(struct target *target,
        const uint8_t *data, const uint8_t *mask,
        uint32_t offset, uint32_t count)
{
    int res;
 
    /* Retrieve the MCU's flash page size, in bytes. */
    uint32_t page_size;
    res = samd_get_flash_page_info(target, &page_size, NULL);
    if (res != ERROR_OK) {
        LOG_ERROR("Couldn't determine Flash page size");
        return res;
    }
 
    /* Make sure the size is sane. */
    assert(page_size <= SAMD_PAGE_SIZE_MAX &&
        page_size >= offset + count);
 
    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)
        return res;
 
    /* Modify buffer and check if really changed */
    bool changed = false;
    uint32_t i;
    for (i = 0; i < count; i++) {
        uint8_t old_b = buf[offset+i];
        uint8_t new_b = (old_b & ~mask[i]) | (data[i] & mask[i]);
        buf[offset+i] = new_b;
        if (old_b != new_b)
            changed = true;
    }
 
    if (!changed)
        return ERROR_OK;
 
    res = same5_pre_write_check(target);
    if (res != ERROR_OK)
        return res;
 
    res = same5_erase_block(target, SAMD_USER_ROW);
    if (res != ERROR_OK) {
        LOG_ERROR("Couldn't erase user row");
        return res;
    }
 
    /* Write the page buffer back out to the target using Write Quad Word */
    for (i = 0; i < page_size; i += 4 * 4) {
        res = target_write_memory(target, SAMD_USER_ROW + i, 4, 4, buf + i);
        if (res != ERROR_OK)
            return res;
 
        /* Trigger flash write */
        res = same5_issue_nvmctrl_command(target, SAME5_NVM_CMD_WQW);
        if (res != ERROR_OK)
            return res;
    }
 
    return res;
}
 
static int same5_modify_user_row(struct target *target, uint32_t value,
        uint8_t startb, uint8_t endb)
{
    uint8_t buf_val[8] = { 0 };
    uint8_t buf_mask[8] = { 0 };
 
    assert(startb <= endb && endb < 64);
    buf_set_u32(buf_val, startb, endb + 1 - startb, value);
    buf_set_u32(buf_mask, startb, endb + 1 - startb, 0xffffffff);
 
    return same5_modify_user_row_masked(target,
            buf_val, buf_mask, 0, 8);
}
 
static int same5_protect(struct flash_bank *bank, int set, unsigned int first,
        unsigned int last)
{
    int res = ERROR_OK;
 
    /* We can issue lock/unlock region commands with the target running but
     * the settings won't persist unless we're able to modify the LOCK regions
     * and that requires the target to be halted. */
    if (bank->target->state != TARGET_HALTED) {
        LOG_ERROR("Target not halted");
        return ERROR_TARGET_NOT_HALTED;
    }
 
    for (unsigned int prot_block = first; prot_block <= last; prot_block++) {
        if (set != bank->prot_blocks[prot_block].is_protected) {
            /* Load an address that is within this protection block (we use offset 0) */
            res = target_write_u32(bank->target,
                    SAMD_NVMCTRL + SAME5_NVMCTRL_ADDR,
                    bank->prot_blocks[prot_block].offset);
            if (res != ERROR_OK)
                goto exit;
 
            /* Tell the controller to lock that block */
            res = same5_issue_nvmctrl_command(bank->target,
                    set ? SAME5_NVM_CMD_LR : SAME5_NVM_CMD_UR);
            if (res != ERROR_OK)
                goto exit;
        }
    }
 
    /* We've now applied our changes, however they will be undone by the next
     * reset unless we also apply them to the LOCK bits in the User Page.
     * A '1' means unlocked and a '0' means locked. */
    const uint8_t lock[4] = { 0, 0, 0, 0 };
    const uint8_t unlock[4] = { 0xff, 0xff, 0xff, 0xff };
    uint8_t mask[4] = { 0, 0, 0, 0 };
 
    buf_set_u32(mask, first, last + 1 - first, 0xffffffff);
 
    res = same5_modify_user_row_masked(bank->target,
            set ? lock : unlock, mask, 8, 4);
    if (res != ERROR_OK)
        LOG_WARNING("SAM: protect settings were not made persistent!");
 
    res = ERROR_OK;
 
exit:
    same5_protect_check(bank);
 
    return res;
}
 
static int same5_erase(struct flash_bank *bank, unsigned int first,
        unsigned int last)
{
    int res;
    struct samd_info *chip = (struct samd_info *)bank->driver_priv;
 
    if (bank->target->state != TARGET_HALTED) {
        LOG_ERROR("Target not halted");
 
        return ERROR_TARGET_NOT_HALTED;
    }
 
    if (!chip->probed)
        return ERROR_FLASH_BANK_NOT_PROBED;
 
    /* For each sector to be erased */
    for (unsigned int s = first; s <= last; s++) {
        res = same5_erase_block(bank->target, bank->sectors[s].offset);
        if (res != ERROR_OK) {
            LOG_ERROR("SAM: failed to erase sector %d at 0x%08" PRIx32, s, bank->sectors[s].offset);
            return res;
        }
    }
 
    return ERROR_OK;
}
 
 
static int same5_write(struct flash_bank *bank, const uint8_t *buffer,
        uint32_t offset, uint32_t count)
{
    int res;
    uint32_t address;
    uint32_t pg_offset;
    uint32_t nb;
    uint32_t nw;
    struct samd_info *chip = (struct samd_info *)bank->driver_priv;
    uint8_t *pb = NULL;
 
    res = same5_pre_write_check(bank->target);
    if (res != ERROR_OK)
        return res;
 
    if (!chip->probed)
        return ERROR_FLASH_BANK_NOT_PROBED;
 
    res = same5_issue_nvmctrl_command(bank->target, SAME5_NVM_CMD_PBC);
    if (res != ERROR_OK) {
        LOG_ERROR("%s: %d", __func__, __LINE__);
        return res;
    }
 
    while (count) {
        nb = chip->page_size - offset % chip->page_size;
        if (count < nb)
            nb = count;
 
        address = bank->base + offset;
        pg_offset = offset % chip->page_size;
 
        if (offset % 4 || (offset + nb) % 4) {
            /* Either start or end of write is not word aligned */
            if (!pb) {
                pb = malloc(chip->page_size);
                if (!pb)
                    return ERROR_FAIL;
            }
 
            /* Set temporary page buffer to 0xff and overwrite the relevant part */
            memset(pb, 0xff, chip->page_size);
            memcpy(pb + pg_offset, buffer, nb);
 
            /* Align start address to a word boundary */
            address -= offset % 4;
            pg_offset -= offset % 4;
            assert(pg_offset % 4 == 0);
 
            /* Extend length to whole words */
            nw = (nb + offset % 4 + 3) / 4;
            assert(pg_offset + 4 * nw <= chip->page_size);
 
            /* Now we have original data extended by 0xff bytes
             * to the nearest word boundary on both start and end */
            res = target_write_memory(bank->target, address, 4, nw, pb + pg_offset);
        } else {
            assert(nb % 4 == 0);
            nw = nb / 4;
            assert(pg_offset + 4 * nw <= chip->page_size);
 
            /* Word aligned data, use direct write from buffer */
            res = target_write_memory(bank->target, address, 4, nw, buffer);
        }
        if (res != ERROR_OK) {
            LOG_ERROR("%s: %d", __func__, __LINE__);
            goto free_pb;
        }
 
        res = same5_issue_nvmctrl_command(bank->target, SAME5_NVM_CMD_WP);
        if (res != ERROR_OK) {
            LOG_ERROR("%s: write failed at address 0x%08" PRIx32, __func__, address);
            goto free_pb;
        }
 
        /* We're done with the page contents */
        count -= nb;
        offset += nb;
        buffer += nb;
    }
 
free_pb:
    free(pb);
    return res;
}
 
 
FLASH_BANK_COMMAND_HANDLER(same5_flash_bank_command)
{
    if (bank->base != SAMD_FLASH) {
        LOG_ERROR("Address " TARGET_ADDR_FMT " invalid bank address (try "
            "0x%08x[same5] )", bank->base, SAMD_FLASH);
        return ERROR_FAIL;
    }
 
    struct samd_info *chip;
    chip = calloc(1, sizeof(*chip));
    if (!chip) {
        LOG_ERROR("No memory for flash bank chip info");
        return ERROR_FAIL;
    }
 
    chip->target = bank->target;
    chip->probed = false;
 
    bank->driver_priv = chip;
 
    return ERROR_OK;
}
 
 
COMMAND_HANDLER(same5_handle_chip_erase_command)
{
    struct target *target = get_current_target(CMD_CTX);
    if (!target)
        return ERROR_FAIL;
 
    /* Enable access to the DSU by disabling the write protect bit */
    target_write_u32(target, SAME5_PAC, (1<<16) | (1<<5) | (1<<1));
    /* intentionally without error checking - not accessible on secured chip */
 
    /* Tell the DSU to perform a full chip erase.  It takes about 240ms to
     * perform the erase. */
    int res = target_write_u8(target, SAMD_DSU + SAMD_DSU_CTRL_EXT, (1<<4));
    if (res == ERROR_OK)
        command_print(CMD, "chip erase started");
    else
        command_print(CMD, "write to DSU CTRL failed");
 
    return res;
}
 
 
COMMAND_HANDLER(same5_handle_userpage_command)
{
    int res = ERROR_OK;
    struct target *target = get_current_target(CMD_CTX);
    if (!target)
        return ERROR_FAIL;
 
    if (CMD_ARGC > 2) {
        command_print(CMD, "Too much Arguments given.");
        return ERROR_COMMAND_SYNTAX_ERROR;
    }
 
    if (CMD_ARGC >= 1) {
        uint64_t value, mask = NVMUSERROW_SAM_E5_D5_MASK;
        COMMAND_PARSE_NUMBER(u64, CMD_ARGV[0], value);
 
        if (CMD_ARGC == 2) {
            uint64_t mask_temp;
            COMMAND_PARSE_NUMBER(u64, CMD_ARGV[1], mask_temp);
            mask &= mask_temp;
        }
 
        uint8_t val_buf[8], mask_buf[8];
        target_buffer_set_u64(target, val_buf, value);
        target_buffer_set_u64(target, mask_buf, mask);
 
        res = same5_modify_user_row_masked(target,
                val_buf, mask_buf, 0, sizeof(val_buf));
    }
 
    uint8_t buffer[8];
    int res2 = target_read_memory(target, SAMD_USER_ROW, 4, 2, buffer);
    if (res2 == ERROR_OK) {
        uint64_t value = target_buffer_get_u64(target, buffer);
        command_print(CMD, "USER PAGE: 0x%016"PRIX64, value);
    } else {
        LOG_ERROR("USER PAGE could not be read.");
    }
 
    if (CMD_ARGC >= 1)
        return res;
    else
        return res2;
}
 
 
COMMAND_HANDLER(same5_handle_bootloader_command)
{
    int res = ERROR_OK;
    struct target *target = get_current_target(CMD_CTX);
    if (!target)
        return ERROR_FAIL;
 
    if (CMD_ARGC >= 1) {
        unsigned long size;
 
        COMMAND_PARSE_NUMBER(ulong, CMD_ARGV[0], size);
        uint32_t code = (size + 8191) / 8192;
        if (code > 15) {
            command_print(CMD, "Invalid bootloader size.  Please "
                        "see datasheet for a list valid sizes.");
            return ERROR_COMMAND_SYNTAX_ERROR;
        }
 
        res = same5_modify_user_row(target, 15 - code, 26, 29);
    }
 
    uint32_t val;
    int res2 = target_read_u32(target, SAMD_USER_ROW, &val);
    if (res2 == ERROR_OK) {
        uint32_t code = (val >> 26) & 0xf; /* grab size code */
        uint32_t size = (15 - code) * 8192;
        command_print(CMD, "Bootloader protected in the first %"
                      PRIu32 " bytes", size);
    }
 
    if (CMD_ARGC >= 1)
        return res;
    else
        return res2;
}
 
 
COMMAND_HANDLER(samd_handle_reset_deassert)
{
    struct target *target = get_current_target(CMD_CTX);
    int res = ERROR_OK;
    enum reset_types jtag_reset_config = jtag_get_reset_config();
    if (!target)
        return ERROR_FAIL;
 
    /* If the target has been unresponsive before, try to re-establish
     * communication now - CPU is held in reset by DSU, DAP is working */
    if (!target_was_examined(target))
        target_examine_one(target);
    target_poll(target);
 
    /* In case of sysresetreq, debug retains state set in cortex_m_assert_reset()
     * so we just release reset held by DSU
     *
     * n_RESET (srst) clears the DP, so reenable debug and set vector catch here
     *
     * After vectreset DSU release is not needed however makes no harm
     */
    if (target->reset_halt && (jtag_reset_config & RESET_HAS_SRST)) {
        res = target_write_u32(target, DCB_DHCSR, DBGKEY | C_HALT | C_DEBUGEN);
        if (res == ERROR_OK)
            res = target_write_u32(target, DCB_DEMCR,
                TRCENA | VC_HARDERR | VC_BUSERR | VC_CORERESET);
        /* do not return on error here, releasing DSU reset is more important */
    }
 
    /* clear CPU Reset Phase Extension bit */
    int res2 = target_write_u8(target, SAMD_DSU + SAMD_DSU_STATUSA, (1<<1));
    if (res2 != ERROR_OK)
        return res2;
 
    return res;
}
 
static const struct command_registration same5_exec_command_handlers[] = {
    {
        .name = "dsu_reset_deassert",
        .usage = "",
        .handler = samd_handle_reset_deassert,
        .mode = COMMAND_EXEC,
        .help = "Deassert internal reset held by DSU."
    },
    {
        .name = "chip-erase",
        .usage = "",
        .handler = same5_handle_chip_erase_command,
        .mode = COMMAND_EXEC,
        .help = "Erase the entire Flash by using the Chip-"
            "Erase feature in the Device Service Unit (DSU).",
    },
    {
        .name = "bootloader",
        .usage = "[size_in_bytes]",
        .handler = same5_handle_bootloader_command,
        .mode = COMMAND_EXEC,
        .help = "Show or set the bootloader protection size, stored in the User Row. "
            "Changes are stored immediately but take affect after the MCU is "
            "reset.",
    },
    {
        .name = "userpage",
        .usage = "[value] [mask]",
        .handler = same5_handle_userpage_command,
        .mode = COMMAND_EXEC,
        .help = "Show or set the first 64-bit part of user page "
            "located at address 0x804000. Use the optional mask argument "
            "to prevent changes at positions where the bitvalue is zero. "
            "For security reasons the reserved-bits are masked out "
            "in background and therefore cannot be changed.",
    },
    COMMAND_REGISTRATION_DONE
};
 
static const struct command_registration same5_command_handlers[] = {
    {
        .name = "atsame5",
        .mode = COMMAND_ANY,
        .help = "atsame5 flash command group",
        .usage = "",
        .chain = same5_exec_command_handlers,
    },
    COMMAND_REGISTRATION_DONE
};
 
const struct flash_driver atsame5_flash = {
    .name = "atsame5",
    .commands = same5_command_handlers,
    .flash_bank_command = same5_flash_bank_command,
    .erase = same5_erase,
    .protect = same5_protect,
    .write = same5_write,
    .read = default_flash_read,
    .probe = same5_probe,
    .auto_probe = same5_probe,
    .erase_check = default_flash_blank_check,
    .protect_check = same5_protect_check,
    .free_driver_priv = default_flash_free_driver_priv,
};