rp2040/example/boot2/main.c

#include "gpio.h"
#include "ssi_reg.h"

void __attribute__((section(".text.boot2_pre"))) boot2_copy_self(void)
{
    #define BOOT2_FLASHCMD_READ_DATA (0x03)
    #define BOOT2_FLASH_OFFSET       (256)
    extern uint32_t _boot2_copy_self_start_addr;
    extern uint32_t _boot2_copy_self_end_addr;

    io_rw_32 *reg;
    uint32_t cmd;
    uint32_t length, tx_count, rx_count, rx_skip;
    uint8_t *copy_to_addr;
    uint8_t rxbyte;

    /* force QSPI_CS low level as selected */
    reg = (io_rw_32 *)(IO_QSPI_BASE + GPIO_QSPI_CS_CTRL_OFFSET);
    *reg = GPIO_OVER_OUT_FORCE_LOW << GPIO_OVER_OUT_POS;

    /* send command and length */
    cmd = (BOOT2_FLASHCMD_READ_DATA << 24) | BOOT2_FLASH_OFFSET;
    for (int i = 0; i < 4; ++i) {
        ssi_hw->dr0 = cmd >> 24;
        cmd <<= 8;
    }
    /* init parameter */
    length = (uint32_t)&_boot2_copy_self_end_addr - (uint32_t)&_boot2_copy_self_start_addr;
    tx_count = length;
    rx_count = length;
    rx_skip = 4;
    copy_to_addr = (uint8_t *)&_boot2_copy_self_start_addr;
    /* copy data from flash to ram */
    while (tx_count || rx_skip || rx_count) {
        uint32_t tx_level = ssi_hw->txflr;
        uint32_t rx_level = ssi_hw->rxflr;
        if (tx_count && tx_level + rx_level < 14) {
            ssi_hw->dr0 = 0;
            tx_count--;
        }
        if (rx_level) {
            rxbyte = ssi_hw->dr0;
            if (rx_skip) {
                rx_skip--;
            } else {
                *copy_to_addr++ = rxbyte;
                rx_count--;
            }
        }
    }

    /* force QSPI_CS high level as disselected */
    *reg = GPIO_OVER_OUT_FORCE_HIGH << GPIO_OVER_OUT_POS;
}

int main(void)
{
    return 0;
}