编写一个支持zynq 32M flash大小的fsbl代码

以下是一个简单的支持 Zynq 32M Flash 大小的 FSBL 代码示例：

#include <stdio.h>
#include "xil_printf.h"
#include "xil_io.h"
#include "xil_types.h"
#include "xparameters.h"
#include "xil_exception.h"
#include "xil_cache.h"
#include "xil_mmu.h"
#include "xil_ddr.h"

#define FLASH_BASEADDR XPAR_MICROBLAZE_0_S_AXI_BASEADDR

// Flash commands
#define RDID_CMD 0x9F    // Read Identification
#define RDSR_CMD 0x05    // Read Status Register
#define WREN_CMD 0x06    // Write Enable
#define PP_CMD   0x02    // Page Program
#define SE_CMD   0xD8    // Sector Erase

// Flash status register bits
#define WIP_BIT  0x01    // Write In Progress

// Function prototypes
void init_mmu();
u32 read_flash_id();
void erase_flash();
void program_flash(u32 address, u8 *data, u32 size);

int main() {
    init_mmu();

    xil_printf("FSBL Booting...\r\n");

    // Read the Flash ID
    u32 flash_id = read_flash_id();
    xil_printf("Flash ID: %08x\r\n", flash_id);

    // Erase the Flash
    erase_flash();

    // Program the Flash
    u8 data[4096] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77};
    program_flash(FLASH_BASEADDR, data, sizeof(data));

    xil_printf("FSBL Done.\r\n");

    return 0;
}

void init_mmu() {
    // Initialize the MMU
    Xil_SetTlbAttributes(0x0, 0x14de2);
    Xil_SetTlbAttributes(0x80000000, 0x14de2);
    Xil_SetTlbAttributes(0xC0000000, 0x14de2);
    Xil_SetTlbAttributes(0xE0000000, 0x14de2);
    Xil_SetTlbAttributes(0xF8000000, 0x14de2);
}

u32 read_flash_id() {
    // Read the Flash ID
    u8 cmd = RDID_CMD;
    Xil_Out8(FLASH_BASEADDR, cmd);
    u32 id = Xil_In32(FLASH_BASEADDR + 1);
    return id;
}

void erase_flash() {
    // Enable write access
    u8 cmd = WREN_CMD;
    Xil_Out8(FLASH_BASEADDR, cmd);

    // Send sector erase command
    cmd = SE_CMD;
    Xil_Out8(FLASH_BASEADDR, cmd);
    Xil_Out8(FLASH_BASEADDR + 1, 0x00);
    Xil_Out8(FLASH_BASEADDR + 2, 0x00);
    Xil_Out8(FLASH_BASEADDR + 3, 0x00);

    // Wait for erase to complete
    u8 status = 0;
    do {
        cmd = RDSR_CMD;
        Xil_Out8(FLASH_BASEADDR, cmd);
        status = Xil_In8(FLASH_BASEADDR + 1);
    } while (status & WIP_BIT);
}

void program_flash(u32 address, u8 *data, u32 size) {
    // Enable write access
    u8 cmd = WREN_CMD;
    Xil_Out8(FLASH_BASEADDR, cmd);

    // Program the data
    u32 i;
    for (i = 0; i < size; i += 4) {
        cmd = PP_CMD;
        Xil_Out8(FLASH_BASEADDR, cmd);
        Xil_Out8(FLASH_BASEADDR + 1, (address >> 16) & 0xFF);
        Xil_Out8(FLASH_BASE