Merge pull request #407 from tomdeboer/STML1_Fix

[fw/stlink] / src / common.c

#define DEBUG_FLASH 0

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "stlink.h"
#include "stlink/mmap.h"
#include "stlink/logging.h"

#ifndef _WIN32
#define O_BINARY 0
#endif

/* todo: stm32l15xxx flash memory, pm0062 manual */

/* stm32f FPEC flash controller interface, pm0063 manual */
// TODO - all of this needs to be abstracted out....
// STM32F05x is identical, based on RM0091 (DM00031936, Doc ID 018940 Rev 2, August 2012)
#define FLASH_REGS_ADDR 0x40022000
#define FLASH_REGS_SIZE 0x28

#define FLASH_ACR (FLASH_REGS_ADDR + 0x00)
#define FLASH_KEYR (FLASH_REGS_ADDR + 0x04)
#define FLASH_SR (FLASH_REGS_ADDR + 0x0c)
#define FLASH_CR (FLASH_REGS_ADDR + 0x10)
#define FLASH_AR (FLASH_REGS_ADDR + 0x14)
#define FLASH_OBR (FLASH_REGS_ADDR + 0x1c)
#define FLASH_WRPR (FLASH_REGS_ADDR + 0x20)

// For STM32F05x, the RDPTR_KEY may be wrong, but as it is not used anywhere...
#define FLASH_RDPTR_KEY 0x00a5
#define FLASH_KEY1 0x45670123
#define FLASH_KEY2 0xcdef89ab

#define FLASH_SR_BSY 0
#define FLASH_SR_EOP 5

#define FLASH_CR_PG 0
#define FLASH_CR_PER 1
#define FLASH_CR_MER 2
#define FLASH_CR_STRT 6
#define FLASH_CR_LOCK 7


//32L = 32F1 same CoreID as 32F4!
#define STM32L_FLASH_REGS_ADDR ((uint32_t)0x40023c00)
#define STM32L_FLASH_ACR (STM32L_FLASH_REGS_ADDR + 0x00)
#define STM32L_FLASH_PECR (STM32L_FLASH_REGS_ADDR + 0x04)
#define STM32L_FLASH_PDKEYR (STM32L_FLASH_REGS_ADDR + 0x08)
#define STM32L_FLASH_PEKEYR (STM32L_FLASH_REGS_ADDR + 0x0c)
#define STM32L_FLASH_PRGKEYR (STM32L_FLASH_REGS_ADDR + 0x10)
#define STM32L_FLASH_OPTKEYR (STM32L_FLASH_REGS_ADDR + 0x14)
#define STM32L_FLASH_SR (STM32L_FLASH_REGS_ADDR + 0x18)
#define STM32L_FLASH_OBR (STM32L_FLASH_REGS_ADDR + 0x1c)
#define STM32L_FLASH_WRPR (STM32L_FLASH_REGS_ADDR + 0x20)
#define FLASH_L1_FPRG 10
#define FLASH_L1_PROG 3

//32L4 register base is at FLASH_REGS_ADDR (0x40022000)
#define STM32L4_FLASH_KEYR      (FLASH_REGS_ADDR + 0x08)
#define STM32L4_FLASH_SR        (FLASH_REGS_ADDR + 0x10)
#define STM32L4_FLASH_CR        (FLASH_REGS_ADDR + 0x14)
#define STM32L4_FLASH_OPTR      (FLASH_REGS_ADDR + 0x20)

#define STM32L4_FLASH_SR_BSY            16
#define STM32L4_FLASH_SR_ERRMASK        0x3f8 /* SR [9:3] */

#define STM32L4_FLASH_CR_LOCK   31      /* Lock control register */
#define STM32L4_FLASH_CR_PG     0       /* Program */
#define STM32L4_FLASH_CR_PER    1       /* Page erase */
#define STM32L4_FLASH_CR_MER1   2       /* Bank 1 erase */
#define STM32L4_FLASH_CR_MER2   15      /* Bank 2 erase */
#define STM32L4_FLASH_CR_STRT   16      /* Start command */
#define STM32L4_FLASH_CR_BKER   11      /* Bank select for page erase */
#define STM32L4_FLASH_CR_PNB    3       /* Page number (8 bits) */
// Bits requesting flash operations (useful when we want to clear them)
#define STM32L4_FLASH_CR_OPBITS                                     \
    ((1lu<<STM32L4_FLASH_CR_PG) | (1lu<<STM32L4_FLASH_CR_PER)       \
    | (1lu<<STM32L4_FLASH_CR_MER1) | (1lu<<STM32L4_FLASH_CR_MER1))
// Page is fully specified by BKER and PNB
#define STM32L4_FLASH_CR_PAGEMASK (0x1fflu << STM32L4_FLASH_CR_PNB)

#define STM32L4_FLASH_OPTR_DUALBANK     21

//STM32L0x flash register base and offsets
//same as 32L1 above
// RM0090 - DM00031020.pdf
#define STM32L0_FLASH_REGS_ADDR ((uint32_t)0x40022000)
#define FLASH_ACR_OFF     ((uint32_t) 0x00)
#define FLASH_PECR_OFF    ((uint32_t) 0x04)
#define FLASH_PDKEYR_OFF  ((uint32_t) 0x08)
#define FLASH_PEKEYR_OFF  ((uint32_t) 0x0c)
#define FLASH_PRGKEYR_OFF ((uint32_t) 0x10)
#define FLASH_OPTKEYR_OFF ((uint32_t) 0x14)
#define FLASH_SR_OFF      ((uint32_t) 0x18)
#define FLASH_OBR_OFF     ((uint32_t) 0x1c)
#define FLASH_WRPR_OFF    ((uint32_t) 0x20)



//STM32F4
#define FLASH_F4_REGS_ADDR ((uint32_t)0x40023c00)
#define FLASH_F4_KEYR (FLASH_F4_REGS_ADDR + 0x04)
#define FLASH_F4_OPT_KEYR (FLASH_F4_REGS_ADDR + 0x08)
#define FLASH_F4_SR (FLASH_F4_REGS_ADDR + 0x0c)
#define FLASH_F4_CR (FLASH_F4_REGS_ADDR + 0x10)
#define FLASH_F4_OPT_CR (FLASH_F4_REGS_ADDR + 0x14)
#define FLASH_F4_CR_STRT 16
#define FLASH_F4_CR_LOCK 31
#define FLASH_F4_CR_SER 1
#define FLASH_F4_CR_SNB 3
#define FLASH_F4_CR_SNB_MASK 0xf8
#define FLASH_F4_SR_BSY 16

#define L1_WRITE_BLOCK_SIZE 0x80
#define L0_WRITE_BLOCK_SIZE 0x40

void write_uint32(unsigned char* buf, uint32_t ui) {
    if (!is_bigendian()) { // le -> le (don't swap)
        buf[0] = ((unsigned char*) &ui)[0];
        buf[1] = ((unsigned char*) &ui)[1];
        buf[2] = ((unsigned char*) &ui)[2];
        buf[3] = ((unsigned char*) &ui)[3];
    } else {
        buf[0] = ((unsigned char*) &ui)[3];
        buf[1] = ((unsigned char*) &ui)[2];
        buf[2] = ((unsigned char*) &ui)[1];
        buf[3] = ((unsigned char*) &ui)[0];
    }
}

void write_uint16(unsigned char* buf, uint16_t ui) {
    if (!is_bigendian()) { // le -> le (don't swap)
        buf[0] = ((unsigned char*) &ui)[0];
        buf[1] = ((unsigned char*) &ui)[1];
    } else {
        buf[0] = ((unsigned char*) &ui)[1];
        buf[1] = ((unsigned char*) &ui)[0];
    }
}

uint32_t read_uint32(const unsigned char *c, const int pt) {
    uint32_t ui;
    char *p = (char *) &ui;

    if (!is_bigendian()) { // le -> le (don't swap)
        p[0] = c[pt + 0];
        p[1] = c[pt + 1];
        p[2] = c[pt + 2];
        p[3] = c[pt + 3];
    } else {
        p[0] = c[pt + 3];
        p[1] = c[pt + 2];
        p[2] = c[pt + 1];
        p[3] = c[pt + 0];
    }
    return ui;
}

static uint32_t __attribute__((unused)) read_flash_rdp(stlink_t *sl) {
    uint32_t rdp;
    stlink_read_debug32(sl, FLASH_WRPR, &rdp);
    return rdp & 0xff;
}

static inline uint32_t read_flash_wrpr(stlink_t *sl) {
    uint32_t wrpr;
    stlink_read_debug32(sl, FLASH_WRPR, &wrpr);
    return wrpr;
}

static inline uint32_t read_flash_obr(stlink_t *sl) {
    uint32_t obr;
    stlink_read_debug32(sl, FLASH_OBR, &obr);
    return obr;
}

static inline uint32_t read_flash_cr(stlink_t *sl) {
    uint32_t reg, res;

    if (sl->flash_type == FLASH_TYPE_F4)
        reg = FLASH_F4_CR;
    else if (sl->flash_type == FLASH_TYPE_L4)
        reg = STM32L4_FLASH_CR;
    else
        reg = FLASH_CR;

    stlink_read_debug32(sl, reg, &res);

#if DEBUG_FLASH
    fprintf(stdout, "CR:0x%x\n", res);
#endif
    return res;
}

static inline unsigned int is_flash_locked(stlink_t *sl) {
    /* return non zero for true */
    uint32_t cr_lock_shift, cr = read_flash_cr(sl);

    if (sl->flash_type == FLASH_TYPE_F4)
        cr_lock_shift = FLASH_F4_CR_LOCK;
    else if (sl->flash_type == FLASH_TYPE_L4)
        cr_lock_shift = STM32L4_FLASH_CR_LOCK;
    else
        cr_lock_shift = FLASH_CR_LOCK;

    return cr & (1 << cr_lock_shift);
}

static void unlock_flash(stlink_t *sl) {
    uint32_t key_reg;
    /* the unlock sequence consists of 2 write cycles where
       2 key values are written to the FLASH_KEYR register.
       an invalid sequence results in a definitive lock of
       the FPEC block until next reset.
       */
    if (sl->flash_type == FLASH_TYPE_F4)
        key_reg = FLASH_F4_KEYR;
    else if (sl->flash_type == FLASH_TYPE_L4)
        key_reg = STM32L4_FLASH_KEYR;
    else
        key_reg = FLASH_KEYR;

    stlink_write_debug32(sl, key_reg, FLASH_KEY1);
    stlink_write_debug32(sl, key_reg, FLASH_KEY2);
}

static int unlock_flash_if(stlink_t *sl) {
    /* unlock flash if already locked */

    if (is_flash_locked(sl)) {
        unlock_flash(sl);
        if (is_flash_locked(sl)) {
            WLOG("Failed to unlock flash!\n");
            return -1;
        }
    }
    DLOG("Successfully unlocked flash\n");
    return 0;
}

static void lock_flash(stlink_t *sl) {
    uint32_t cr_lock_shift, cr_reg, n;

    if (sl->flash_type == FLASH_TYPE_F4) {
        cr_reg = FLASH_F4_CR;
        cr_lock_shift = FLASH_F4_CR_LOCK;
    } else if (sl->flash_type == FLASH_TYPE_L4) {
        cr_reg = STM32L4_FLASH_CR;
        cr_lock_shift = STM32L4_FLASH_CR_LOCK;
    } else {
        cr_reg = FLASH_CR;
        cr_lock_shift = FLASH_CR_LOCK;
    }

    n = read_flash_cr(sl) | (1 << cr_lock_shift);
    stlink_write_debug32(sl, cr_reg, n);
}


static void set_flash_cr_pg(stlink_t *sl) {
    uint32_t cr_reg, x;

    x = read_flash_cr(sl);

    if (sl->flash_type == FLASH_TYPE_F4) {
        cr_reg = FLASH_F4_CR;
        x |= 1 << FLASH_CR_PG;
    } else if (sl->flash_type == FLASH_TYPE_L4) {
        cr_reg = STM32L4_FLASH_CR;
        x &= ~STM32L4_FLASH_CR_OPBITS;
        x |= 1 << STM32L4_FLASH_CR_PG;
    } else {
        cr_reg = FLASH_CR;
        x = 1 << FLASH_CR_PG;
    }

    stlink_write_debug32(sl, cr_reg, x);
}

static void __attribute__((unused)) clear_flash_cr_pg(stlink_t *sl) {
    uint32_t cr_reg, n;

    if (sl->flash_type == FLASH_TYPE_F4)
        cr_reg = FLASH_F4_CR;
    else if (sl->flash_type == FLASH_TYPE_L4)
        cr_reg = STM32L4_FLASH_CR;
    else
        cr_reg = FLASH_CR;

    n = read_flash_cr(sl) & ~(1 << FLASH_CR_PG);
    stlink_write_debug32(sl, cr_reg, n);
}

static void set_flash_cr_per(stlink_t *sl) {
    const uint32_t n = 1 << FLASH_CR_PER;
    stlink_write_debug32(sl, FLASH_CR, n);
}

static void __attribute__((unused)) clear_flash_cr_per(stlink_t *sl) {
    const uint32_t n = read_flash_cr(sl) & ~(1 << FLASH_CR_PER);
    stlink_write_debug32(sl, FLASH_CR, n);
}

static void set_flash_cr_mer(stlink_t *sl) {
    uint32_t val, cr_reg, cr_mer;

    if (sl->flash_type == FLASH_TYPE_F4) {
        cr_reg = FLASH_F4_CR;
        cr_mer = 1 << FLASH_CR_MER;
    } else if (sl->flash_type == FLASH_TYPE_L4) {
        cr_reg = STM32L4_FLASH_CR;
        cr_mer = (1 << STM32L4_FLASH_CR_MER1) | (1 << STM32L4_FLASH_CR_MER2);
    } else {
        cr_reg = FLASH_CR;
        cr_mer = 1 << FLASH_CR_MER;
    }

    stlink_read_debug32(sl, cr_reg, &val);
    val |= cr_mer;
    stlink_write_debug32(sl, cr_reg, val);
}

static void __attribute__((unused)) clear_flash_cr_mer(stlink_t *sl) {
    uint32_t val, cr_reg, cr_mer;

    if (sl->flash_type == FLASH_TYPE_F4) {
        cr_reg = FLASH_F4_CR;
        cr_mer = 1 << FLASH_CR_MER;
    } else if (sl->flash_type == FLASH_TYPE_L4) {
        cr_reg = STM32L4_FLASH_CR;
        cr_mer = (1 << STM32L4_FLASH_CR_MER1) | (1 << STM32L4_FLASH_CR_MER2);
    } else {
        cr_reg = FLASH_CR;
        cr_mer = 1 << FLASH_CR_MER;
    }

    stlink_read_debug32(sl, cr_reg, &val);
    val &= ~cr_mer;
    stlink_write_debug32(sl, cr_reg, val);
}

static void set_flash_cr_strt(stlink_t *sl) {
    uint32_t val, cr_reg, cr_strt;

    if (sl->flash_type == FLASH_TYPE_F4) {
        cr_reg = FLASH_F4_CR;
        cr_strt = 1 << FLASH_F4_CR_STRT;
    } else if (sl->flash_type == FLASH_TYPE_L4) {
        cr_reg = STM32L4_FLASH_CR;
        cr_strt = 1 << STM32L4_FLASH_CR_STRT;
    } else {
        cr_reg = FLASH_CR;
        cr_strt = 1 << FLASH_CR_STRT;
    }

    stlink_read_debug32(sl, cr_reg, &val);
    val |= cr_strt;
    stlink_write_debug32(sl, cr_reg, val);
}

static inline uint32_t read_flash_acr(stlink_t *sl) {
    uint32_t acr;
    stlink_read_debug32(sl, FLASH_ACR, &acr);
    return acr;
}

static inline uint32_t read_flash_sr(stlink_t *sl) {
    uint32_t res, sr_reg;

    if (sl->flash_type == FLASH_TYPE_F4)
        sr_reg = FLASH_F4_SR;
    else if (sl->flash_type == FLASH_TYPE_L4)
        sr_reg = STM32L4_FLASH_SR;
    else
        sr_reg = FLASH_SR;

    stlink_read_debug32(sl, sr_reg, &res);

    return res;
}

static inline unsigned int is_flash_busy(stlink_t *sl) {
    uint32_t sr_busy_shift;

    if (sl->flash_type == FLASH_TYPE_F4)
        sr_busy_shift = FLASH_F4_SR_BSY;
    else if (sl->flash_type == FLASH_TYPE_L4)
        sr_busy_shift = STM32L4_FLASH_SR_BSY;
    else
        sr_busy_shift = FLASH_SR_BSY;

    return read_flash_sr(sl) & (1 << sr_busy_shift);
}

static void wait_flash_busy(stlink_t *sl) {
    /* todo: add some delays here */
    while (is_flash_busy(sl))
        ;
}

static void wait_flash_busy_progress(stlink_t *sl) {
    int i = 0;
    fprintf(stdout, "Mass erasing");
    fflush(stdout);
    while (is_flash_busy(sl)) {
        usleep(10000);
        i++;
        if (i % 100 == 0) {
            fprintf(stdout, ".");
            fflush(stdout);
        }
    }
    fprintf(stdout, "\n");
}

static inline unsigned int is_flash_eop(stlink_t *sl) {
    return read_flash_sr(sl) & (1 << FLASH_SR_EOP);
}

static void __attribute__((unused)) clear_flash_sr_eop(stlink_t *sl) {
    const uint32_t n = read_flash_sr(sl) & ~(1 << FLASH_SR_EOP);
    stlink_write_debug32(sl, FLASH_SR, n);
}

static void __attribute__((unused)) wait_flash_eop(stlink_t *sl) {
    /* todo: add some delays here */
    while (is_flash_eop(sl) == 0)
        ;
}

static inline void write_flash_ar(stlink_t *sl, uint32_t n) {
    stlink_write_debug32(sl, FLASH_AR, n);
}

static inline void write_flash_cr_psiz(stlink_t *sl, uint32_t n) {
    uint32_t x = read_flash_cr(sl);
    x &= ~(0x03 << 8);
    x |= (n << 8);
#if DEBUG_FLASH
    fprintf(stdout, "PSIZ:0x%x 0x%x\n", x, n);
#endif
    stlink_write_debug32(sl, FLASH_F4_CR, x);
}


static inline void write_flash_cr_snb(stlink_t *sl, uint32_t n) {
    uint32_t x = read_flash_cr(sl);
    x &= ~FLASH_F4_CR_SNB_MASK;
    x |= (n << FLASH_F4_CR_SNB);
    x |= (1 << FLASH_F4_CR_SER);
#if DEBUG_FLASH
    fprintf(stdout, "SNB:0x%x 0x%x\n", x, n);
#endif
    stlink_write_debug32(sl, FLASH_F4_CR, x);
}

static inline void write_flash_cr_bker_pnb(stlink_t *sl, uint32_t n) {
    stlink_write_debug32(sl, STM32L4_FLASH_SR, 0xFFFFFFFF & ~(1<<STM32L4_FLASH_SR_BSY));
    uint32_t x = read_flash_cr(sl);
    x &=~ STM32L4_FLASH_CR_OPBITS;
    x &=~ STM32L4_FLASH_CR_PAGEMASK;
    x &= ~(1<<STM32L4_FLASH_CR_MER1);
    x &= ~(1<<STM32L4_FLASH_CR_MER2);
    x |= (n << STM32L4_FLASH_CR_PNB);
    x |= (1lu << STM32L4_FLASH_CR_PER);
#if DEBUG_FLASH
    fprintf(stdout, "BKER:PNB:0x%x 0x%x\n", x, n);
#endif
    stlink_write_debug32(sl, STM32L4_FLASH_CR, x);
}

// Delegates to the backends...

void stlink_close(stlink_t *sl) {
    DLOG("*** stlink_close ***\n");
    if (!sl)
         return;
    sl->backend->close(sl);
    free(sl);
}

int stlink_exit_debug_mode(stlink_t *sl) {
    int ret;

    DLOG("*** stlink_exit_debug_mode ***\n");
    ret = stlink_write_debug32(sl, DHCSR, DBGKEY);
    if (ret == -1)
        return ret;

    return sl->backend->exit_debug_mode(sl);
}

int stlink_enter_swd_mode(stlink_t *sl) {
    DLOG("*** stlink_enter_swd_mode ***\n");
    return sl->backend->enter_swd_mode(sl);
}

// Force the core into the debug mode -> halted state.
int stlink_force_debug(stlink_t *sl) {
    DLOG("*** stlink_force_debug_mode ***\n");
    return sl->backend->force_debug(sl);
}

int stlink_exit_dfu_mode(stlink_t *sl) {
    DLOG("*** stlink_exit_dfu_mode ***\n");
    return sl->backend->exit_dfu_mode(sl);
}

int stlink_core_id(stlink_t *sl) {
    int ret;

    DLOG("*** stlink_core_id ***\n");
    ret = sl->backend->core_id(sl);
    if (ret == -1) {
        ELOG("Failed to read core_id\n");
        return ret;
    }
    if (sl->verbose > 2)
        stlink_print_data(sl);
    DLOG("core_id = 0x%08x\n", sl->core_id);
    return ret;
}

int stlink_chip_id(stlink_t *sl, uint32_t *chip_id) {
    int ret;

    ret = stlink_read_debug32(sl, 0xE0042000, chip_id);
    if (ret == -1)
        return ret;

    if (*chip_id == 0)
        ret = stlink_read_debug32(sl, 0x40015800, chip_id);    //Try Corex M0 DBGMCU_IDCODE register address

    return ret;
}

/**
 * Cortex m3 tech ref manual, CPUID register description
 * @param sl stlink context
 * @param cpuid pointer to the result object
 */
int stlink_cpu_id(stlink_t *sl, cortex_m3_cpuid_t *cpuid) {
    uint32_t raw;

    if (stlink_read_debug32(sl, CM3_REG_CPUID, &raw))
        return -1;

    cpuid->implementer_id = (raw >> 24) & 0x7f;
    cpuid->variant = (raw >> 20) & 0xf;
    cpuid->part = (raw >> 4) & 0xfff;
    cpuid->revision = raw & 0xf;
    return 0;
}

/**
 * reads and decodes the flash parameters, as dynamically as possible
 * @param sl
 * @return 0 for success, or -1 for unsupported core type.
 */
int stlink_load_device_params(stlink_t *sl) {
    ILOG("Loading device parameters....\n");
    const chip_params_t *params = NULL;
    stlink_core_id(sl);
    uint32_t chip_id;
    uint32_t flash_size;

    stlink_chip_id(sl, &chip_id);
    sl->chip_id = chip_id & 0xfff;
    /* Fix chip_id for F4 rev A errata , Read CPU ID, as CoreID is the same for F2/F4*/
    if (sl->chip_id == 0x411) {
        uint32_t cpuid;
        stlink_read_debug32(sl, 0xE000ED00, &cpuid);
        if ((cpuid  & 0xfff0) == 0xc240)
            sl->chip_id = 0x413;
    }

    for (size_t i = 0; i < sizeof(devices) / sizeof(devices[0]); i++) {
        if(devices[i].chip_id == sl->chip_id) {
            params = &devices[i];
            break;
        }
    }
    if (params == NULL) {
        WLOG("unknown chip id! %#x\n", chip_id);
        return -1;
    }

    // These are fixed...
    sl->flash_base = STM32_FLASH_BASE;
    sl->sram_base = STM32_SRAM_BASE;
    stlink_read_debug32(sl,(params->flash_size_reg) & ~3, &flash_size);
    if (params->flash_size_reg & 2)
        flash_size = flash_size >>16;
    flash_size = flash_size & 0xffff;

    if ((sl->chip_id == STM32_CHIPID_L1_MEDIUM || sl->chip_id == STM32_CHIPID_L1_MEDIUM_PLUS) && ( flash_size == 0 )) {
        sl->flash_size = 128 * 1024;
    } else if (sl->chip_id == STM32_CHIPID_L1_CAT2) {
        sl->flash_size = (flash_size & 0xff) * 1024;
    } else if ((sl->chip_id & 0xFFF) == STM32_CHIPID_L1_HIGH) {
        // 0 is 384k and 1 is 256k
        if ( flash_size == 0 ) {
            sl->flash_size = 384 * 1024;
        } else {
            sl->flash_size = 256 * 1024;
        }
    } else {
        sl->flash_size = flash_size * 1024;
    }
    sl->flash_type = params->flash_type;
    sl->flash_pgsz = params->flash_pagesize;
    sl->sram_size = params->sram_size;
    sl->sys_base = params->bootrom_base;
    sl->sys_size = params->bootrom_size;

    //medium and low devices have the same chipid. ram size depends on flash size.
    //STM32F100xx datasheet Doc ID 16455 Table 2
    if(sl->chip_id == STM32_CHIPID_F1_VL_MEDIUM_LOW && sl->flash_size < 64 * 1024){
        sl->sram_size = 0x1000;
    }

    ILOG("Device connected is: %s, id %#x\n", params->description, chip_id);
    // TODO make note of variable page size here.....
    ILOG("SRAM size: %#x bytes (%d KiB), Flash: %#x bytes (%d KiB) in pages of %zd bytes\n",
            sl->sram_size, sl->sram_size / 1024, sl->flash_size, sl->flash_size / 1024,
            sl->flash_pgsz);
    return 0;
}

int stlink_reset(stlink_t *sl) {
    DLOG("*** stlink_reset ***\n");
    return sl->backend->reset(sl);
}

int stlink_jtag_reset(stlink_t *sl, int value) {
    DLOG("*** stlink_jtag_reset ***\n");
    return sl->backend->jtag_reset(sl, value);
}

int stlink_run(stlink_t *sl) {
    DLOG("*** stlink_run ***\n");
    return sl->backend->run(sl);
}

int stlink_status(stlink_t *sl) {
    int ret;

    DLOG("*** stlink_status ***\n");
    ret = sl->backend->status(sl);
    stlink_core_stat(sl);

    return ret;
}

/**
 * Decode the version bits, originally from -sg, verified with usb
 * @param sl stlink context, assumed to contain valid data in the buffer
 * @param slv output parsed version object
 */
void _parse_version(stlink_t *sl, stlink_version_t *slv) {
    uint32_t b0 = sl->q_buf[0]; //lsb
    uint32_t b1 = sl->q_buf[1];
    uint32_t b2 = sl->q_buf[2];
    uint32_t b3 = sl->q_buf[3];
    uint32_t b4 = sl->q_buf[4];
    uint32_t b5 = sl->q_buf[5]; //msb

    // b0 b1                       || b2 b3  | b4 b5
    // 4b        | 6b     | 6b     || 2B     | 2B
    // stlink_v  | jtag_v | swim_v || st_vid | stlink_pid

    slv->stlink_v = (b0 & 0xf0) >> 4;
    slv->jtag_v = ((b0 & 0x0f) << 2) | ((b1 & 0xc0) >> 6);
    slv->swim_v = b1 & 0x3f;
    slv->st_vid = (b3 << 8) | b2;
    slv->stlink_pid = (b5 << 8) | b4;
    return;
}

int stlink_version(stlink_t *sl) {
    DLOG("*** looking up stlink version\n");
    if (sl->backend->version(sl))
        return -1;

    _parse_version(sl, &sl->version);

    DLOG("st vid         = 0x%04x (expect 0x%04x)\n", sl->version.st_vid, USB_ST_VID);
    DLOG("stlink pid     = 0x%04x\n", sl->version.stlink_pid);
    DLOG("stlink version = 0x%x\n", sl->version.stlink_v);
    DLOG("jtag version   = 0x%x\n", sl->version.jtag_v);
    DLOG("swim version   = 0x%x\n", sl->version.swim_v);
    if (sl->version.jtag_v == 0) {
        DLOG("    notice: the firmware doesn't support a jtag/swd interface\n");
    }
    if (sl->version.swim_v == 0) {
        DLOG("    notice: the firmware doesn't support a swim interface\n");
    }

    return 0;
}

int stlink_target_voltage(stlink_t *sl) {
    int voltage = -1;
    DLOG("*** reading target voltage\n");
    if (sl->backend->target_voltage != NULL) {
        voltage = sl->backend->target_voltage(sl);
        if (voltage != -1) {
            DLOG("target voltage = %ldmV\n", voltage);
        } else {
            DLOG("error reading target voltage\n");
        }
    } else {
        DLOG("reading voltage not supported by backend\n");
    }
    return voltage;
}

int stlink_read_debug32(stlink_t *sl, uint32_t addr, uint32_t *data) {
    int ret;

    ret = sl->backend->read_debug32(sl, addr, data);
    if (!ret)
            DLOG("*** stlink_read_debug32 %x is %#x\n", *data, addr);

        return ret;
}

int stlink_write_debug32(stlink_t *sl, uint32_t addr, uint32_t data) {
    DLOG("*** stlink_write_debug32 %x to %#x\n", data, addr);
    return sl->backend->write_debug32(sl, addr, data);
}

int stlink_write_mem32(stlink_t *sl, uint32_t addr, uint16_t len) {
    DLOG("*** stlink_write_mem32 %u bytes to %#x\n", len, addr);
    if (len % 4 != 0) {
        fprintf(stderr, "Error: Data length doesn't have a 32 bit alignment: +%d byte.\n", len % 4);
        abort();
    }
    return sl->backend->write_mem32(sl, addr, len);
}

int stlink_read_mem32(stlink_t *sl, uint32_t addr, uint16_t len) {
    DLOG("*** stlink_read_mem32 ***\n");
    if (len % 4 != 0) { // !!! never ever: fw gives just wrong values
        fprintf(stderr, "Error: Data length doesn't have a 32 bit alignment: +%d byte.\n",
                len % 4);
        abort();
    }
    return sl->backend->read_mem32(sl, addr, len);
}

int stlink_write_mem8(stlink_t *sl, uint32_t addr, uint16_t len) {
    DLOG("*** stlink_write_mem8 ***\n");
    if (len > 0x40 ) { // !!! never ever: Writing more then 0x40 bytes gives unexpected behaviour
        fprintf(stderr, "Error: Data length > 64: +%d byte.\n",
                len);
        abort();
    }
    return sl->backend->write_mem8(sl, addr, len);
}

int stlink_read_all_regs(stlink_t *sl, reg *regp) {
    DLOG("*** stlink_read_all_regs ***\n");
    return sl->backend->read_all_regs(sl, regp);
}

int stlink_read_all_unsupported_regs(stlink_t *sl, reg *regp) {
    DLOG("*** stlink_read_all_unsupported_regs ***\n");
    return sl->backend->read_all_unsupported_regs(sl, regp);
}

int stlink_write_reg(stlink_t *sl, uint32_t reg, int idx) {
    DLOG("*** stlink_write_reg\n");
    return sl->backend->write_reg(sl, reg, idx);
}

int stlink_read_reg(stlink_t *sl, int r_idx, reg *regp) {
    DLOG("*** stlink_read_reg\n");
    DLOG(" (%d) ***\n", r_idx);

    if (r_idx > 20 || r_idx < 0) {
        fprintf(stderr, "Error: register index must be in [0..20]\n");
        return -1;
    }

    return sl->backend->read_reg(sl, r_idx, regp);
}

int stlink_read_unsupported_reg(stlink_t *sl, int r_idx, reg *regp) {
    int r_convert;

    DLOG("*** stlink_read_unsupported_reg\n");
    DLOG(" (%d) ***\n", r_idx);

    /* Convert to values used by DCRSR */
    if (r_idx >= 0x1C && r_idx <= 0x1F) { /* primask, basepri, faultmask, or control */
        r_convert = 0x14;
    } else if (r_idx == 0x40) {     /* FPSCR */
        r_convert = 0x21;
    } else if (r_idx >= 0x20 && r_idx < 0x40) {
        r_convert = 0x40 + (r_idx - 0x20);
    } else {
        fprintf(stderr, "Error: register address must be in [0x1C..0x40]\n");
        return -1;
    }

    return sl->backend->read_unsupported_reg(sl, r_convert, regp);
}

int stlink_write_unsupported_reg(stlink_t *sl, uint32_t val, int r_idx, reg *regp) {
    int r_convert;

    DLOG("*** stlink_write_unsupported_reg\n");
    DLOG(" (%d) ***\n", r_idx);

    /* Convert to values used by DCRSR */
    if (r_idx >= 0x1C && r_idx <= 0x1F) { /* primask, basepri, faultmask, or control */
        r_convert = r_idx;  /* The backend function handles this */
    } else if (r_idx == 0x40) {     /* FPSCR */
        r_convert = 0x21;
    } else if (r_idx >= 0x20 && r_idx < 0x40) {
        r_convert = 0x40 + (r_idx - 0x20);
    } else {
        fprintf(stderr, "Error: register address must be in [0x1C..0x40]\n");
        return -1;
    }

    return sl->backend->write_unsupported_reg(sl, val, r_convert, regp);
}

unsigned int is_core_halted(stlink_t *sl) {
    /* return non zero if core is halted */
    stlink_status(sl);
    return sl->q_buf[0] == STLINK_CORE_HALTED;
}

int stlink_step(stlink_t *sl) {
    DLOG("*** stlink_step ***\n");
    return sl->backend->step(sl);
}

int stlink_current_mode(stlink_t *sl) {
    int mode = sl->backend->current_mode(sl);
    switch (mode) {
    case STLINK_DEV_DFU_MODE:
        DLOG("stlink current mode: dfu\n");
        return mode;
    case STLINK_DEV_DEBUG_MODE:
        DLOG("stlink current mode: debug (jtag or swd)\n");
        return mode;
    case STLINK_DEV_MASS_MODE:
        DLOG("stlink current mode: mass\n");
        return mode;
    }
    DLOG("stlink mode: unknown!\n");
    return STLINK_DEV_UNKNOWN_MODE;
}




// End of delegates....  Common code below here...

// Endianness
// http://www.ibm.com/developerworks/aix/library/au-endianc/index.html
// const int i = 1;
// #define is_bigendian() ( (*(char*)&i) == 0 )

inline unsigned int is_bigendian(void) {
    static volatile const unsigned int i = 1;
    return *(volatile const char*) &i == 0;
}

uint16_t read_uint16(const unsigned char *c, const int pt) {
    uint32_t ui;
    char *p = (char *) &ui;

    if (!is_bigendian()) { // le -> le (don't swap)
        p[0] = c[pt + 0];
        p[1] = c[pt + 1];
    } else {
        p[0] = c[pt + 1];
        p[1] = c[pt + 0];
    }
    return ui;
}

// same as above with entrypoint.

void stlink_run_at(stlink_t *sl, stm32_addr_t addr) {
    stlink_write_reg(sl, addr, 15); /* pc register */

    stlink_run(sl);

    while (is_core_halted(sl) == 0)
        usleep(3000000);
}

void stlink_core_stat(stlink_t *sl) {
    if (sl->q_len <= 0)
        return;

    switch (sl->q_buf[0]) {
    case STLINK_CORE_RUNNING:
        sl->core_stat = STLINK_CORE_RUNNING;
        DLOG("  core status: running\n");
        return;
    case STLINK_CORE_HALTED:
        sl->core_stat = STLINK_CORE_HALTED;
        DLOG("  core status: halted\n");
        return;
    default:
        sl->core_stat = STLINK_CORE_STAT_UNKNOWN;
        fprintf(stderr, "  core status: unknown\n");
    }
}

void stlink_print_data(stlink_t * sl) {
    if (sl->q_len <= 0 || sl->verbose < UDEBUG)
        return;
    if (sl->verbose > 2)
        fprintf(stdout, "data_len = %d 0x%x\n", sl->q_len, sl->q_len);

    for (int i = 0; i < sl->q_len; i++) {
        if (i % 16 == 0) {
            /*
               if (sl->q_data_dir == Q_DATA_OUT)
               fprintf(stdout, "\n<- 0x%08x ", sl->q_addr + i);
               else
               fprintf(stdout, "\n-> 0x%08x ", sl->q_addr + i);
               */
        }
        fprintf(stdout, " %02x", (unsigned int) sl->q_buf[i]);
    }
    fputs("\n\n", stdout);
}

/* memory mapped file */

typedef struct mapped_file {
    uint8_t* base;
    size_t len;
} mapped_file_t;

#define MAPPED_FILE_INITIALIZER { NULL, 0 }

static int map_file(mapped_file_t* mf, const char* path) {
    int error = -1;
    struct stat st;

    const int fd = open(path, O_RDONLY | O_BINARY);
    if (fd == -1) {
        fprintf(stderr, "open(%s) == -1\n", path);
        return -1;
    }

    if (fstat(fd, &st) == -1) {
        fprintf(stderr, "fstat() == -1\n");
        goto on_error;
    }

    mf->base = (uint8_t*) mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
    if (mf->base == MAP_FAILED) {
        fprintf(stderr, "mmap() == MAP_FAILED\n");
        goto on_error;
    }

    mf->len = st.st_size;

    /* success */
    error = 0;

on_error:
    close(fd);

    return error;
}

static void unmap_file(mapped_file_t * mf) {
    munmap((void*) mf->base, mf->len);
    mf->base = (unsigned char*) MAP_FAILED;
    mf->len = 0;
}

/* Limit the block size to compare to 0x1800
   Anything larger will stall the STLINK2
   Maybe STLINK V1 needs smaller value!*/
static int check_file(stlink_t* sl, mapped_file_t* mf, stm32_addr_t addr) {
    size_t off;
    size_t n_cmp = sl->flash_pgsz;
    if ( n_cmp > 0x1800)
        n_cmp = 0x1800;

    for (off = 0; off < mf->len; off += n_cmp) {
        size_t aligned_size;

        /* adjust last page size */
        size_t cmp_size = n_cmp;
        if ((off + n_cmp) > mf->len)
            cmp_size = mf->len - off;

        aligned_size = cmp_size;
        if (aligned_size & (4 - 1))
            aligned_size = (cmp_size + 4) & ~(4 - 1);

        stlink_read_mem32(sl, addr + off, aligned_size);

        if (memcmp(sl->q_buf, mf->base + off, cmp_size))
            return -1;
    }

    return 0;
}

int stlink_fwrite_sram
(stlink_t * sl, const char* path, stm32_addr_t addr) {
    /* write the file in sram at addr */

    int error = -1;
    size_t off;
    size_t len;
    mapped_file_t mf = MAPPED_FILE_INITIALIZER;
    uint32_t val;


    if (map_file(&mf, path) == -1) {
        fprintf(stderr, "map_file() == -1\n");
        return -1;
    }

    /* check addr range is inside the sram */
    if (addr < sl->sram_base) {
        fprintf(stderr, "addr too low\n");
        goto on_error;
    } else if ((addr + mf.len) < addr) {
        fprintf(stderr, "addr overruns\n");
        goto on_error;
    } else if ((addr + mf.len) > (sl->sram_base + sl->sram_size)) {
        fprintf(stderr, "addr too high\n");
        goto on_error;
    } else if (addr & 3) {
        /* todo */
        fprintf(stderr, "unaligned addr\n");
        goto on_error;
    }

    len = mf.len;

    if(len & 3) {
      len -= len & 3;
    }

    /* do the copy by 1k blocks */
    for (off = 0; off < len; off += 1024) {
        size_t size = 1024;
        if ((off + size) > len)
            size = len - off;

        memcpy(sl->q_buf, mf.base + off, size);

        /* round size if needed */
        if (size & 3)
            size += 2;

        stlink_write_mem32(sl, addr + off, size);
    }

    if(mf.len > len) {
        memcpy(sl->q_buf, mf.base + len, mf.len - len);
        stlink_write_mem8(sl, addr + len, mf.len - len);
    }

    /* check the file ha been written */
    if (check_file(sl, &mf, addr) == -1) {
        fprintf(stderr, "check_file() == -1\n");
        goto on_error;
    }

    /* success */
    error = 0;
    /* set stack*/
    stlink_read_debug32(sl, addr, &val);
    stlink_write_reg(sl, val, 13);
    /* Set PC to the reset routine*/
    stlink_read_debug32(sl, addr + 4, &val);
    stlink_write_reg(sl, val, 15);
    stlink_run(sl);

on_error:
    unmap_file(&mf);
    return error;
}

int stlink_fread(stlink_t* sl, const char* path, stm32_addr_t addr, size_t size) {
    /* read size bytes from addr to file */

    int error = -1;
    size_t off;

    const int fd = open(path, O_RDWR | O_TRUNC | O_CREAT, 00700);
    if (fd == -1) {
        fprintf(stderr, "open(%s) == -1\n", path);
        return -1;
    }

    if (size <1)
        size = sl->flash_size;

    if (size > sl->flash_size)
        size = sl->flash_size;

    size_t cmp_size = (sl->flash_pgsz > 0x1800)? 0x1800:sl->flash_pgsz;
    for (off = 0; off < size; off += cmp_size) {
        size_t aligned_size;

        /* adjust last page size */
        if ((off + cmp_size) > size)
            cmp_size = size - off;

        aligned_size = cmp_size;
        if (aligned_size & (4 - 1))
            aligned_size = (cmp_size + 4) & ~(4 - 1);

        stlink_read_mem32(sl, addr + off, aligned_size);

        if (write(fd, sl->q_buf, sl->q_len) != (ssize_t) aligned_size) {
            fprintf(stderr, "write() != aligned_size\n");
            goto on_error;
        }
    }

    /* success */
    error = 0;

on_error:
    close(fd);

    return error;
}

int write_buffer_to_sram(stlink_t *sl, flash_loader_t* fl, const uint8_t* buf, size_t size) {
    /* write the buffer right after the loader */
    size_t chunk = size & ~0x3;
    size_t rem   = size & 0x3;
    if (chunk) {
        memcpy(sl->q_buf, buf, chunk);
        stlink_write_mem32(sl, fl->buf_addr, chunk);
    }
    if (rem) {
        memcpy(sl->q_buf, buf+chunk, rem);
        stlink_write_mem8(sl, (fl->buf_addr)+chunk, rem);
    }
    return 0;
}

uint32_t calculate_F4_sectornum(uint32_t flashaddr){
    uint32_t offset = 0;
    flashaddr &= ~STM32_FLASH_BASE;     //Page now holding the actual flash address
    if (flashaddr >= 0x100000) {
        offset = 12;
        flashaddr -= 0x100000;
    } 
    if (flashaddr<0x4000) return (offset + 0);
    else if(flashaddr<0x8000) return(offset + 1);
    else if(flashaddr<0xc000) return(offset + 2);
    else if(flashaddr<0x10000) return(offset + 3);
    else if(flashaddr<0x20000) return(offset + 4);
    else return offset + (flashaddr/0x20000) +4;

}

uint32_t calculate_F7_sectornum(uint32_t flashaddr){
    flashaddr &= ~STM32_FLASH_BASE;     //Page now holding the actual flash address
        if(flashaddr<0x20000) return(flashaddr/0x8000);
    else if(flashaddr<0x40000) return(4);
    else return(flashaddr/0x40000) +4;

}

// Returns BKER:PNB for the given page address
uint32_t calculate_L4_page(stlink_t *sl, uint32_t flashaddr) {
    uint32_t bker = 0;
    uint32_t flashopt;
    stlink_read_debug32(sl, STM32L4_FLASH_OPTR, &flashopt);
    flashaddr -= STM32_FLASH_BASE;
    if (flashopt & (1lu << STM32L4_FLASH_OPTR_DUALBANK)) {
        uint32_t banksize = sl->flash_size / 2;
        if (flashaddr >= banksize) {
            flashaddr -= banksize;
            bker = 0x100;
        }
    }
    // For 1MB chips without the dual-bank option set, the page address will
    // overflow into the BKER bit, which gives us the correct bank:page value.
    return bker | flashaddr/sl->flash_pgsz;
}

uint32_t stlink_calculate_pagesize(stlink_t *sl, uint32_t flashaddr){
    if ((sl->chip_id == STM32_CHIPID_F2) || (sl->chip_id == STM32_CHIPID_F4) || (sl->chip_id == STM32_CHIPID_F4_DE) ||
            (sl->chip_id == STM32_CHIPID_F4_LP) || (sl->chip_id == STM32_CHIPID_F4_HD) || (sl->chip_id == STM32_CHIPID_F411RE) ||
            (sl->chip_id == STM32_CHIPID_F446) || (sl->chip_id == STM32_CHIPID_F4_DSI)) {
        uint32_t sector=calculate_F4_sectornum(flashaddr);
        if (sector>= 12) {
            sector -= 12;
        }
        if (sector<4) sl->flash_pgsz=0x4000;
        else if(sector<5) sl->flash_pgsz=0x10000;
        else sl->flash_pgsz=0x20000;
    }
    else if (sl->chip_id == STM32_CHIPID_F7) {
        uint32_t sector=calculate_F7_sectornum(flashaddr);
        if (sector<4) sl->flash_pgsz=0x8000;
        else if(sector<5) sl->flash_pgsz=0x20000;
        else sl->flash_pgsz=0x40000;
    }
    return (sl->flash_pgsz);
}

/**
 * Erase a page of flash, assumes sl is fully populated with things like chip/core ids
 * @param sl stlink context
 * @param flashaddr an address in the flash page to erase
 * @return 0 on success -ve on failure
 */
int stlink_erase_flash_page(stlink_t *sl, stm32_addr_t flashaddr)
{
    if (sl->flash_type == FLASH_TYPE_F4 || sl->flash_type == FLASH_TYPE_L4) {
        /* wait for ongoing op to finish */
        wait_flash_busy(sl);

        /* unlock if locked */
        unlock_flash_if(sl);

        /* select the page to erase */
        if (sl->chip_id == STM32_CHIPID_L4) {
            // calculate the actual bank+page from the address
            uint32_t page = calculate_L4_page(sl, flashaddr);

            fprintf(stderr, "EraseFlash - Page:0x%x Size:0x%x ", page, stlink_calculate_pagesize(sl, flashaddr));

            write_flash_cr_bker_pnb(sl, page);
        } else if (sl->chip_id == STM32_CHIPID_F7) {
            // calculate the actual page from the address
            uint32_t sector=calculate_F7_sectornum(flashaddr);

            fprintf(stderr, "EraseFlash - Sector:0x%x Size:0x%x ", sector, stlink_calculate_pagesize(sl, flashaddr));

            write_flash_cr_snb(sl, sector);
        } else {
            // calculate the actual page from the address
            uint32_t sector=calculate_F4_sectornum(flashaddr);

            fprintf(stderr, "EraseFlash - Sector:0x%x Size:0x%x ", sector, stlink_calculate_pagesize(sl, flashaddr));
        
            //the SNB values for flash sectors in the second bank do not directly follow the values for the first bank on 2mb devices...
            if (sector >= 12) sector += 4;

            write_flash_cr_snb(sl, sector);
        }

        /* start erase operation */
        set_flash_cr_strt(sl);

        /* wait for completion */
        wait_flash_busy(sl);

        /* relock the flash */
        //todo: fails to program if this is in
        lock_flash(sl);
#if DEBUG_FLASH
        fprintf(stdout, "Erase Final CR:0x%x\n", read_flash_cr(sl));
#endif
    } else if (sl->flash_type == FLASH_TYPE_L0) {

        uint32_t val;
        uint32_t flash_regs_base;
        if (sl->chip_id == STM32_CHIPID_L0 || sl->chip_id == STM32_CHIPID_L0_CAT5) {
            flash_regs_base = STM32L0_FLASH_REGS_ADDR;
        } else {
            flash_regs_base = STM32L_FLASH_REGS_ADDR;
        }

        /* check if the locks are set */
        stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
        if((val & (1<<0))||(val & (1<<1))) {
            /* disable pecr protection */
            stlink_write_debug32(sl, flash_regs_base + FLASH_PEKEYR_OFF, 0x89abcdef);
            stlink_write_debug32(sl, flash_regs_base + FLASH_PEKEYR_OFF, 0x02030405);

            /* check pecr.pelock is cleared */
            stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
            if (val & (1 << 0)) {
                WLOG("pecr.pelock not clear (%#x)\n", val);
                return -1;
            }

            /* unlock program memory */
            stlink_write_debug32(sl, flash_regs_base + FLASH_PRGKEYR_OFF, 0x8c9daebf);
            stlink_write_debug32(sl, flash_regs_base + FLASH_PRGKEYR_OFF, 0x13141516);

            /* check pecr.prglock is cleared */
            stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
            if (val & (1 << 1)) {
                WLOG("pecr.prglock not clear (%#x)\n", val);
                return -1;
            }
        }

        /* set pecr.{erase,prog} */
        val |= (1 << 9) | (1 << 3);
        stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);
#if 0 /* fix_to_be_confirmed */

        /* wait for sr.busy to be cleared
         * MP: Test shows that busy bit is not set here. Perhaps, PM0062 is
         * wrong and we do not need to wait here for clearing the busy bit.
         * TEXANE: ok, if experience says so and it works for you, we comment
         * it. If someone has a problem, please drop an email.
         */
        do {
            stlink_read_debug32(sl, STM32L_FLASH_SR, &val)
        } while((val & (1 << 0)) != 0);

#endif /* fix_to_be_confirmed */

        /* write 0 to the first word of the page to be erased */
        stlink_write_debug32(sl, flashaddr, 0);

        /* MP: It is better to wait for clearing the busy bit after issuing
           page erase command, even though PM0062 recommends to wait before it.
           Test shows that a few iterations is performed in the following loop
           before busy bit is cleared.*/
        do {
            stlink_read_debug32(sl, flash_regs_base + FLASH_SR_OFF, &val);
        } while ((val & (1 << 0)) != 0);

        /* reset lock bits */
        stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
        val |= (1 << 0) | (1 << 1) | (1 << 2);
        stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);
    } else if (sl->flash_type == FLASH_TYPE_F0)  {
        /* wait for ongoing op to finish */
        wait_flash_busy(sl);

        /* unlock if locked */
        unlock_flash_if(sl);

        /* set the page erase bit */
        set_flash_cr_per(sl);

        /* select the page to erase */
        write_flash_ar(sl, flashaddr);

        /* start erase operation, reset by hw with bsy bit */
        set_flash_cr_strt(sl);

        /* wait for completion */
        wait_flash_busy(sl);

        /* relock the flash */
        lock_flash(sl);
    } else {
        WLOG("unknown coreid %x, page erase failed\n", sl->core_id);
        return -1;
    }

    /* todo: verify the erased page */

    return 0;
}

int stlink_erase_flash_mass(stlink_t *sl) {
    if (sl->flash_type == FLASH_TYPE_L0) {
        /* erase each page */
        int i = 0, num_pages = sl->flash_size/sl->flash_pgsz;
        for (i = 0; i < num_pages; i++) {
            /* addr must be an addr inside the page */
            stm32_addr_t addr = sl->flash_base + i * sl->flash_pgsz;
            if (stlink_erase_flash_page(sl, addr) == -1) {
                WLOG("Failed to erase_flash_page(%#zx) == -1\n", addr);
                return -1;
            }
            fprintf(stdout,"-> Flash page at %5d/%5d erased\n", i, num_pages);
            fflush(stdout);
        }
        fprintf(stdout, "\n");
    } else {
        /* wait for ongoing op to finish */
        wait_flash_busy(sl);

        /* unlock if locked */
        unlock_flash_if(sl);

        /* set the mass erase bit */
        set_flash_cr_mer(sl);

        /* start erase operation, reset by hw with bsy bit */
        set_flash_cr_strt(sl);

        /* wait for completion */
        wait_flash_busy_progress(sl);

        /* relock the flash */
        lock_flash(sl);

        /* todo: verify the erased memory */
    }
    return 0;
}

int init_flash_loader(stlink_t *sl, flash_loader_t* fl) {
    size_t size;

    /* allocate the loader in sram */
    if (write_loader_to_sram(sl, &fl->loader_addr, &size) == -1) {
        WLOG("Failed to write flash loader to sram!\n");
        return -1;
    }

    /* allocate a one page buffer in sram right after loader */
    fl->buf_addr = fl->loader_addr + size;
    ILOG("Successfully loaded flash loader in sram\n");
    return 0;
}

int write_loader_to_sram(stlink_t *sl, stm32_addr_t* addr, size_t* size) {
    /* from openocd, contrib/loaders/flash/stm32.s */
    static const uint8_t loader_code_stm32vl[] = {
        0x08, 0x4c, /* ldr      r4, STM32_FLASH_BASE */
        0x1c, 0x44, /* add      r4, r3 */
        /* write_half_word: */
        0x01, 0x23, /* movs     r3, #0x01 */
        0x23, 0x61, /* str      r3, [r4, #STM32_FLASH_CR_OFFSET] */
        0x30, 0xf8, 0x02, 0x3b, /* ldrh r3, [r0], #0x02 */
        0x21, 0xf8, 0x02, 0x3b, /* strh r3, [r1], #0x02 */
        /* busy: */
        0xe3, 0x68, /* ldr      r3, [r4, #STM32_FLASH_SR_OFFSET] */
        0x13, 0xf0, 0x01, 0x0f, /* tst  r3, #0x01 */
        0xfb, 0xd0, /* beq      busy */
        0x13, 0xf0, 0x14, 0x0f, /* tst  r3, #0x14 */
        0x01, 0xd1, /* bne      exit */
        0x01, 0x3a, /* subs     r2, r2, #0x01 */
        0xf0, 0xd1, /* bne      write_half_word */
        /* exit: */
        0x00, 0xbe, /* bkpt     #0x00 */
        0x00, 0x20, 0x02, 0x40, /* STM32_FLASH_BASE: .word 0x40022000 */
    };

    /* flashloaders/stm32f0.s -- thumb1 only, same sequence as for STM32VL, bank ignored */
    static const uint8_t loader_code_stm32f0[] = {
#if 1
        /*
         * These two NOPs here are a safety precaution, added by Pekka Nikander
         * while debugging the STM32F05x support.  They may not be needed, but
         * there were strange problems with simpler programs, like a program
         * that had just a breakpoint or a program that first moved zero to register r2
         * and then had a breakpoint.  So, it appears safest to have these two nops.
         *
         * Feel free to remove them, if you dare, but then please do test the result
         * rigorously.  Also, if you remove these, it may be a good idea first to
         * #if 0 them out, with a comment when these were taken out, and to remove
         * these only a few months later...  But YMMV.
         */
        0x00, 0x30, //     nop     /* add r0,#0 */
        0x00, 0x30, //     nop     /* add r0,#0 */
#endif
        0x0A, 0x4C, //     ldr     r4, STM32_FLASH_BASE
        0x01, 0x25, //     mov     r5, #1            /*  FLASH_CR_PG, FLASH_SR_BUSY */
        0x04, 0x26, //     mov     r6, #4            /*  PGERR  */
        // write_half_word:
        0x23, 0x69, //     ldr     r3, [r4, #16]     /*  FLASH->CR   */
        0x2B, 0x43, //     orr     r3, r5
        0x23, 0x61, //     str     r3, [r4, #16]     /*  FLASH->CR |= FLASH_CR_PG */
        0x03, 0x88, //     ldrh    r3, [r0]          /*  r3 = *sram */
        0x0B, 0x80, //     strh    r3, [r1]          /*  *flash = r3 */
        // busy:
        0xE3, 0x68, //     ldr     r3, [r4, #12]     /*  FLASH->SR  */
        0x2B, 0x42, //     tst     r3, r5            /*  FLASH_SR_BUSY  */
        0xFC, 0xD0, //     beq     busy

        0x33, 0x42, //     tst     r3, r6            /*  PGERR  */
        0x04, 0xD1, //     bne     exit

        0x02, 0x30, //     add     r0, r0, #2        /*  sram += 2  */
        0x02, 0x31, //     add     r1, r1, #2        /*  flash += 2  */
        0x01, 0x3A, //     sub     r2, r2, #0x01     /*  count--  */
        0x00, 0x2A, //     cmp     r2, #0
        0xF0, 0xD1, //     bne     write_half_word
        // exit:
        0x23, 0x69, //     ldr     r3, [r4, #16]     /*  FLASH->CR  */
        0xAB, 0x43, //     bic     r3, r5
        0x23, 0x61, //     str     r3, [r4, #16]     /*  FLASH->CR &= ~FLASH_CR_PG  */
        0x00, 0xBE, //     bkpt #0x00
        0x00, 0x20, 0x02, 0x40, /* STM32_FLASH_BASE: .word 0x40022000 */
    };

    static const uint8_t loader_code_stm32l[] = {

        /* openocd.git/contrib/loaders/flash/stm32lx.S
           r0, input, dest addr
           r1, input, source addr
           r2, input, word count
           r3, output, word count
           */

        0x00, 0x23,
        0x04, 0xe0,

        0x51, 0xf8, 0x04, 0xcb,
        0x40, 0xf8, 0x04, 0xcb,
        0x01, 0x33,

        0x93, 0x42,
        0xf8, 0xd3,
        0x00, 0xbe
    };

    static const uint8_t loader_code_stm32l0[] = {

        /*
           r0, input, dest addr
           r1, input, source addr
           r2, input, word count
           r3, output, word count
         */

        0x00, 0x23,
        0x04, 0xe0,

        0x0c, 0x68,
        0x04, 0x60,
        0x01, 0x33,
        0x04, 0x31,
        0x04, 0x30,

        0x93, 0x42,
        0xf8, 0xd3,
        0x00, 0xbe
    };

    static const uint8_t loader_code_stm32f4[] = {
        // flashloaders/stm32f4.s

        0x07, 0x4b,

        0x62, 0xb1,
        0x04, 0x68,
        0x0c, 0x60,

        0xdc, 0x89,
        0x14, 0xf0, 0x01, 0x0f,
        0xfb, 0xd1,
        0x00, 0xf1, 0x04, 0x00,
        0x01, 0xf1, 0x04, 0x01,
        0xa2, 0xf1, 0x01, 0x02,
        0xf1, 0xe7,

        0x00, 0xbe,

        0x00, 0x3c, 0x02, 0x40,
    };

    static const uint8_t loader_code_stm32f4_lv[] = {
        // flashloaders/stm32f4lv.s
        0x92, 0x00,

        0x08, 0x4b,
        0x62, 0xb1,
        0x04, 0x78,
        0x0c, 0x70,

        0xdc, 0x89,
        0x14, 0xf0, 0x01, 0x0f,
        0xfb, 0xd1,
        0x00, 0xf1, 0x01, 0x00,
        0x01, 0xf1, 0x01, 0x01,
        0xa2, 0xf1, 0x01, 0x02,
        0xf1, 0xe7,

        0x00, 0xbe,
        0x00, 0xbf,

        0x00, 0x3c, 0x02, 0x40,
    };

    static const uint8_t loader_code_stm32l4[] = {
        // flashloaders/stm32l4.s
        0x08, 0x4b,             // start: ldr   r3, [pc, #32] ; <flash_base>
        0x72, 0xb1,             // next:  cbz   r2, <done>
        0x04, 0x68,             //        ldr   r4, [r0, #0]
        0x45, 0x68,             //        ldr   r5, [r0, #4]
        0x0c, 0x60,             //        str   r4, [r1, #0]
        0x4d, 0x60,             //        str   r5, [r1, #4]
        0x5c, 0x8a,             // wait:  ldrh  r4, [r3, #18]
        0x14, 0xf0, 0x01, 0x0f, //        tst.w r4, #1
        0xfb, 0xd1,             //        bne.n <wait>
        0x00, 0xf1, 0x08, 0x00, //        add.w r0, r0, #8
        0x01, 0xf1, 0x08, 0x01, //        add.w r1, r1, #8
        0xa2, 0xf1, 0x02, 0x02, //        add.w r2, r2, #2
        0xef, 0xe7,             //        b.n   <next>
        0x00, 0xbe,             // done:  bkpt  0x0000
        0x00, 0x20, 0x02, 0x40  // flash_base:  .word 0x40022000
    };

        static const uint8_t loader_code_stm32f7[] = {
        0x08, 0x4b,
        0x72, 0xb1,
        0x04, 0x68,
        0x0c, 0x60,
        0xbf, 0xf3, 0x4f, 0x8f,        // DSB Memory barrier for in order flash write
        0xdc, 0x89,
        0x14, 0xf0, 0x01, 0x0f,
        0xfb, 0xd1,
        0x00, 0xf1, 0x04, 0x00,
        0x01, 0xf1, 0x04, 0x01,
        0xa2, 0xf1, 0x01, 0x02,
        0xef, 0xe7,
        0x00, 0xbe,                   //     bkpt       #0x00
        0x00, 0x3c, 0x02, 0x40,
    };

    const uint8_t* loader_code;
    size_t loader_size;

    if (sl->chip_id == STM32_CHIPID_L1_MEDIUM || sl->chip_id == STM32_CHIPID_L1_CAT2
            || sl->chip_id == STM32_CHIPID_L1_MEDIUM_PLUS || sl->chip_id == STM32_CHIPID_L1_HIGH
            || sl->chip_id == STM32_CHIPID_L152_RE) { /* stm32l */
        loader_code = loader_code_stm32l;
        loader_size = sizeof(loader_code_stm32l);
    } else if (sl->core_id == STM32VL_CORE_ID 
            || sl->chip_id == STM32_CHIPID_F3
            || sl->chip_id == STM32_CHIPID_F3_SMALL
            || sl->chip_id == STM32_CHIPID_F303_HIGH
            || sl->chip_id == STM32_CHIPID_F37x
            || sl->chip_id == STM32_CHIPID_F334) {
        loader_code = loader_code_stm32vl;
        loader_size = sizeof(loader_code_stm32vl);
    } else if (sl->chip_id == STM32_CHIPID_F2 || sl->chip_id == STM32_CHIPID_F4 || (sl->chip_id == STM32_CHIPID_F4_DE) ||
            sl->chip_id == STM32_CHIPID_F4_LP || sl->chip_id == STM32_CHIPID_F4_HD || (sl->chip_id == STM32_CHIPID_F411RE) ||
            (sl->chip_id == STM32_CHIPID_F446) || (sl->chip_id == STM32_CHIPID_F4_DSI)){
        int voltage = stlink_target_voltage(sl);
        if (voltage == -1) {
            printf("Failed to read Target voltage\n");
            return voltage;
        } else if (voltage > 2700) {
            loader_code = loader_code_stm32f4;
            loader_size = sizeof(loader_code_stm32f4);
        } else {
            loader_code = loader_code_stm32f4_lv;
            loader_size = sizeof(loader_code_stm32f4_lv);
        }
    } else if (sl->chip_id == STM32_CHIPID_F7){
        loader_code = loader_code_stm32f7;
        loader_size = sizeof(loader_code_stm32f7);
    } else if (sl->chip_id == STM32_CHIPID_F0 || sl->chip_id == STM32_CHIPID_F04 || sl->chip_id == STM32_CHIPID_F0_CAN || sl->chip_id == STM32_CHIPID_F0_SMALL || sl->chip_id == STM32_CHIPID_F09X) {
        loader_code = loader_code_stm32f0;
        loader_size = sizeof(loader_code_stm32f0);
    } else if (sl->chip_id == STM32_CHIPID_L0 || sl->chip_id == STM32_CHIPID_L0_CAT5) {
        loader_code = loader_code_stm32l0;
        loader_size = sizeof(loader_code_stm32l0);
    } else if (sl->chip_id == STM32_CHIPID_L4) {
        loader_code = loader_code_stm32l4;
        loader_size = sizeof(loader_code_stm32l4);
    } else {
        ELOG("unknown coreid, not sure what flash loader to use, aborting!: %x\n", sl->core_id);
        return -1;
    }

    memcpy(sl->q_buf, loader_code, loader_size);
    stlink_write_mem32(sl, sl->sram_base, loader_size);

    *addr = sl->sram_base;
    *size = loader_size;

    /* success */
    return 0;
}

int stlink_fcheck_flash(stlink_t *sl, const char* path, stm32_addr_t addr) {
    /* check the contents of path are at addr */

    int res;
    mapped_file_t mf = MAPPED_FILE_INITIALIZER;

    if (map_file(&mf, path) == -1)
        return -1;

    res = check_file(sl, &mf, addr);

    unmap_file(&mf);

    return res;
}

/**
 * Verify addr..addr+len is binary identical to base...base+len
 * @param sl stlink context
 * @param address stm device address
 * @param data host side buffer to check against
 * @param length how much
 * @return 0 for success, -ve for failure
 */
int stlink_verify_write_flash(stlink_t *sl, stm32_addr_t address, uint8_t *data, unsigned length) {
    size_t off;
    size_t cmp_size = (sl->flash_pgsz > 0x1800)? 0x1800:sl->flash_pgsz;
    ILOG("Starting verification of write complete\n");
    for (off = 0; off < length; off += cmp_size) {
        size_t aligned_size;

        /* adjust last page size */
        if ((off + cmp_size) > length)
            cmp_size = length - off;

        aligned_size = cmp_size;
        if (aligned_size & (4 - 1))
            aligned_size = (cmp_size + 4) & ~(4 - 1);

        stlink_read_mem32(sl, address + off, aligned_size);

        if (memcmp(sl->q_buf, data + off, cmp_size)) {
            ELOG("Verification of flash failed at offset: %zd\n", off);
            return -1;
        }
    }
    ILOG("Flash written and verified! jolly good!\n");
    return 0;

}

int stm32l1_write_half_pages(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uint32_t len, uint32_t pagesize)
{
    unsigned int count;
    unsigned int num_half_pages = len / pagesize;
    uint32_t val;
    uint32_t flash_regs_base;
    flash_loader_t fl;

    if (sl->chip_id == STM32_CHIPID_L0 || sl->chip_id == STM32_CHIPID_L0_CAT5) {
        flash_regs_base = STM32L0_FLASH_REGS_ADDR;
    } else {
        flash_regs_base = STM32L_FLASH_REGS_ADDR;
    }

    ILOG("Starting Half page flash write for STM32L core id\n");
    /* flash loader initialization */
    if (init_flash_loader(sl, &fl) == -1) {
        WLOG("init_flash_loader() == -1\n");
        return -1;
    }
    /* Unlock already done */
    stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
    val |= (1 << FLASH_L1_FPRG);
    stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);

    val |= (1 << FLASH_L1_PROG);
    stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);
    do {
        stlink_read_debug32(sl, flash_regs_base + FLASH_SR_OFF, &val);
    } while ((val & (1 << 0)) != 0);

    for (count = 0; count  < num_half_pages; count ++) {
        if (run_flash_loader(sl, &fl, addr + count * pagesize, base + count * pagesize, pagesize) == -1) {
            WLOG("l1_run_flash_loader(%#zx) failed! == -1\n", addr + count * pagesize);
            stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
            val &= ~((1 << FLASH_L1_FPRG) |(1 << FLASH_L1_PROG));
            stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);
            return -1;
        }
        /* wait for sr.busy to be cleared */
        if (sl->verbose >= 1) {
            /* show progress. writing procedure is slow
               and previous errors are misleading */
            fprintf(stdout, "\r%3u/%u halfpages written", count + 1, num_half_pages);
            fflush(stdout);
        }
        do {
            stlink_read_debug32(sl, flash_regs_base + FLASH_SR_OFF, &val);
        } while ((val & (1 << 0)) != 0);
    }
    stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
    val &= ~(1 << FLASH_L1_PROG);
    stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);
    stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
    val &= ~(1 << FLASH_L1_FPRG);
    stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);

    return 0;
}

int stlink_write_flash(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uint32_t len, uint8_t eraseonly) {
    size_t off;
    flash_loader_t fl;
    ILOG("Attempting to write %d (%#x) bytes to stm32 address: %u (%#x)\n",
            len, len, addr, addr);
    /* check addr range is inside the flash */
    stlink_calculate_pagesize(sl, addr);
    if (addr < sl->flash_base) {
        ELOG("addr too low %#x < %#x\n", addr, sl->flash_base);
        return -1;
    } else if ((addr + len) < addr) {
        ELOG("addr overruns\n");
        return -1;
    } else if ((addr + len) > (sl->flash_base + sl->flash_size)) {
        ELOG("addr too high\n");
        return -1;
    } else if (addr & 1) {
        ELOG("unaligned addr 0x%x\n", addr);
        return -1;
    } else if (len & 1) {
        WLOG("unaligned len 0x%x -- padding with zero\n", len);
        len += 1;
    } else if (addr & (sl->flash_pgsz - 1)) {
        ELOG("addr not a multiple of pagesize, not supported\n");
        return -1;
    }

    // Make sure we've loaded the context with the chip details
    stlink_core_id(sl);
    /* erase each page */
    int page_count = 0;
    for (off = 0; off < len; off += stlink_calculate_pagesize(sl, addr + off)) {
        /* addr must be an addr inside the page */
        if (stlink_erase_flash_page(sl, addr + off) == -1) {
            ELOG("Failed to erase_flash_page(%#zx) == -1\n", addr + off);
            return -1;
        }
        fprintf(stdout,"\rFlash page at addr: 0x%08lx erased",
                (unsigned long)addr + off);
        fflush(stdout);
        page_count++;
    }
    fprintf(stdout,"\n");
    ILOG("Finished erasing %d pages of %d (%#x) bytes\n",
            page_count, sl->flash_pgsz, sl->flash_pgsz);

    if (eraseonly)
        return 0;

    if ((sl->flash_type == FLASH_TYPE_F4) || (sl->flash_type == FLASH_TYPE_L4)) {
        /* todo: check write operation */

        ILOG("Starting Flash write for F2/F4/L4\n");
        /* flash loader initialization */
        if (init_flash_loader(sl, &fl) == -1) {
            ELOG("init_flash_loader() == -1\n");
            return -1;
        }

        /* First unlock the cr */
        unlock_flash_if(sl);

        /* TODO: Check that Voltage range is 2.7 - 3.6 V */
        if (sl->chip_id != STM32_CHIPID_L4) {
            /* set parallelisim to 32 bit*/
            int voltage = stlink_target_voltage(sl);
            if (voltage == -1) {
                printf("Failed to read Target voltage\n");
                return voltage;
            } else if (voltage > 2700) {
                printf("enabling 32-bit flash writes\n");
                write_flash_cr_psiz(sl, 2);
            } else {
                printf("Target voltage (%d mV) too low for 32-bit flash, using 8-bit flash writes\n", voltage);
                write_flash_cr_psiz(sl, 0);
            }
        } else {
            /* L4 does not have a byte-write mode */
            int voltage = stlink_target_voltage(sl);
            if (voltage == -1) {
                printf("Failed to read Target voltage\n");
                return voltage;
            } else if (voltage < 1710) {
                printf("Target voltage (%d mV) too low for flash writes!\n", voltage);
                return -1;
            }
        }

        /* set programming mode */
        set_flash_cr_pg(sl);

        for(off = 0; off < len;) {
            size_t size = len - off > 0x8000 ? 0x8000 : len - off;

            printf("size: %zu\n", size);

            if (run_flash_loader(sl, &fl, addr + off, base + off, size) == -1) {
                ELOG("run_flash_loader(%#zx) failed! == -1\n", addr + off);
                return -1;
            }

            off += size;
        }

        /* Relock flash */
        lock_flash(sl);

    }   //STM32F4END

    else if (sl->flash_type == FLASH_TYPE_L0) {
        /* use fast word write. todo: half page. */
        uint32_t val;
        uint32_t flash_regs_base;
        uint32_t pagesize;

        if (sl->chip_id == STM32_CHIPID_L0 || sl->chip_id == STM32_CHIPID_L0_CAT5) {
            flash_regs_base = STM32L0_FLASH_REGS_ADDR;
            pagesize = L0_WRITE_BLOCK_SIZE;
        } else {
            flash_regs_base = STM32L_FLASH_REGS_ADDR;
            pagesize = L1_WRITE_BLOCK_SIZE;
        }

        /* todo: check write operation */

        /* disable pecr protection */
        stlink_write_debug32(sl, flash_regs_base + FLASH_PEKEYR_OFF, 0x89abcdef);
        stlink_write_debug32(sl, flash_regs_base + FLASH_PEKEYR_OFF, 0x02030405);

        /* check pecr.pelock is cleared */
        stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
        if (val & (1 << 0)) {
            fprintf(stderr, "pecr.pelock not clear\n");
            return -1;
        }

        /* unlock program memory */
        stlink_write_debug32(sl, flash_regs_base + FLASH_PRGKEYR_OFF, 0x8c9daebf);
        stlink_write_debug32(sl, flash_regs_base + FLASH_PRGKEYR_OFF, 0x13141516);

        /* check pecr.prglock is cleared */
        stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
        if (val & (1 << 1)) {
            fprintf(stderr, "pecr.prglock not clear\n");
            return -1;
        }
        off = 0;
        if (len > pagesize) {
            if (stm32l1_write_half_pages(sl, addr, base, len, pagesize) == -1) {
                /* This may happen on a blank device! */
                WLOG("\nwrite_half_pages failed == -1\n");
            } else {
                off = (len / pagesize)*pagesize;
            }
        }

        /* write remainingword in program memory */
        for ( ; off < len; off += sizeof(uint32_t)) {
            uint32_t data;
            if (off > 254)
                fprintf(stdout, "\r");

            if ((off % sl->flash_pgsz) > (sl->flash_pgsz -5)) {
                fprintf(stdout, "\r%3zd/%3zd pages written",
                        off/sl->flash_pgsz, len/sl->flash_pgsz);
                fflush(stdout);
            }

            write_uint32((unsigned char*) &data, *(uint32_t*) (base + off));
            stlink_write_debug32(sl, addr + off, data);

            /* wait for sr.busy to be cleared */
            do {
                stlink_read_debug32(sl, flash_regs_base + FLASH_SR_OFF, &val);
            } while ((val & (1 << 0)) != 0);

            /* todo: check redo write operation */

        }
        fprintf(stdout, "\n");
        /* reset lock bits */
        stlink_read_debug32(sl, flash_regs_base + FLASH_PECR_OFF, &val);
        val |= (1 << 0) | (1 << 1) | (1 << 2);
        stlink_write_debug32(sl, flash_regs_base + FLASH_PECR_OFF, val);
    } else if (sl->flash_type == FLASH_TYPE_F0) {
        ILOG("Starting Flash write for VL/F0/F3 core id\n");
        /* flash loader initialization */
        if (init_flash_loader(sl, &fl) == -1) {
            ELOG("init_flash_loader() == -1\n");
            return -1;
        }

        int write_block_count = 0;
        for (off = 0; off < len; off += sl->flash_pgsz) {
            /* adjust last write size */
            size_t size = sl->flash_pgsz;
            if ((off + sl->flash_pgsz) > len) size = len - off;

            /* unlock and set programming mode */
            unlock_flash_if(sl);
            set_flash_cr_pg(sl);
            //DLOG("Finished setting flash cr pg, running loader!\n");
            if (run_flash_loader(sl, &fl, addr + off, base + off, size) == -1) {
                ELOG("run_flash_loader(%#zx) failed! == -1\n", addr + off);
                return -1;
            }
            lock_flash(sl);
            if (sl->verbose >= 1) {
                /* show progress. writing procedure is slow
                   and previous errors are misleading */
                fprintf(stdout, "\r%3u/%lu pages written", write_block_count++, (unsigned long)len/sl->flash_pgsz);
                fflush(stdout);
            }
        }
        fprintf(stdout, "\n");
    } else {
        ELOG("unknown coreid, not sure how to write: %x\n", sl->core_id);
        return -1;
    }

    return stlink_verify_write_flash(sl, addr, base, len);
}

/**
 * Write the given binary file into flash at address "addr"
 * @param sl
 * @param path readable file path, should be binary image
 * @param addr where to start writing
 * @return 0 on success, -ve on failure.
 */
int stlink_fwrite_flash(stlink_t *sl, const char* path, stm32_addr_t addr) {
    /* write the file in flash at addr */
    int err;
    unsigned int num_empty, index, val;
    unsigned char erased_pattern;
    mapped_file_t mf = MAPPED_FILE_INITIALIZER;

    if (map_file(&mf, path) == -1) {
        ELOG("map_file() == -1\n");
        return -1;
    }

    if (sl->flash_type == FLASH_TYPE_L0)
        erased_pattern = 0x00;
    else
        erased_pattern = 0xff;

    index = mf.len;
    for(num_empty = 0; num_empty != mf.len; ++num_empty) {
        if (mf.base[--index] != erased_pattern) {
            break;
        }
    }
    /* Round down to words */
    num_empty -= (num_empty & 3);
    if(num_empty != 0) {
        ILOG("Ignoring %d bytes of 0x%02x at end of file\n", num_empty, erased_pattern);
    }
    err = stlink_write_flash(sl, addr, mf.base, num_empty == mf.len? mf.len : mf.len - num_empty, num_empty == mf.len);
    /* set stack*/
    stlink_read_debug32(sl, addr, &val);
    stlink_write_reg(sl, val, 13);
    /* Set PC to the reset routine*/
    stlink_read_debug32(sl, addr + 4, &val);
    stlink_write_reg(sl, val, 15);
    stlink_run(sl);
    unmap_file(&mf);
    return err;
}

int run_flash_loader(stlink_t *sl, flash_loader_t* fl, stm32_addr_t target, const uint8_t* buf, size_t size) {

    reg rr;
    int target_reg, source_reg, i = 0;
    size_t count;

    DLOG("Running flash loader, write address:%#x, size: %zd\n", target, size);
    // FIXME This can never return -1
    if (write_buffer_to_sram(sl, fl, buf, size) == -1) {
        // IMPOSSIBLE!
        ELOG("write_buffer_to_sram() == -1\n");
        return -1;
    }

    if (sl->flash_type == FLASH_TYPE_L0) {
        count = size / sizeof(uint32_t);
        if (size % sizeof(uint32_t))
            ++count;
        target_reg = 0;
        source_reg = 1;
    } else if (sl->flash_type == FLASH_TYPE_F0) {
        count = size / sizeof(uint16_t);
        if (size % sizeof(uint16_t))
            ++count;
        target_reg = 1;
        source_reg = 0;
    } else if (sl->flash_type == FLASH_TYPE_F4 || sl->flash_type == FLASH_TYPE_L4) {
        count = size / sizeof(uint32_t);
        if (size % sizeof(uint32_t))
            ++count;
        if (sl->chip_id == STM32_CHIPID_L4) {
            if (count % 2)
                ++count;
        }
        target_reg = 1;
        source_reg = 0;
    } else {
        fprintf(stderr, "unknown coreid 0x%x, don't know what flash loader to use\n", sl->core_id);
        return -1;
    }

    /* setup core */
    stlink_write_reg(sl, fl->buf_addr, source_reg); /* source */
    stlink_write_reg(sl, target, target_reg); /* target */
    stlink_write_reg(sl, count, 2); /* count */
    stlink_write_reg(sl, 0, 3); /* flash bank 0 (input), only used on F0, but armless fopr others */
    stlink_write_reg(sl, fl->loader_addr, 15); /* pc register */

    /* run loader */
    stlink_run(sl);

#define WAIT_ROUNDS 10000
    /* wait until done (reaches breakpoint) */
    for (i = 0; i < WAIT_ROUNDS; i++) {
        usleep(10);
        if (is_core_halted(sl))
            break;
    }

    if (i >= WAIT_ROUNDS) {
        ELOG("flash loader run error\n");
        return -1;
    }

    stlink_read_all_regs(sl, &rr);

    /* check written byte count */
    if (sl->flash_type == FLASH_TYPE_L0) {
        if (rr.r[3] != count) {
            fprintf(stderr, "write error, count == %u\n", rr.r[3]);
            return -1;
        }
    } else {
        if (rr.r[2] != 0) {
            fprintf(stderr, "write error, count == %u\n", rr.r[2]);
            return -1;
        }
    }

    return 0;
}