/*
 * spi_slave_recv_loop.c - SPI从设备持续接收程序
 *
 * 功能：SoC作为SPI从设备，配置与MCU主设备对齐，循环接收并打印数据
 *       MCU每秒发送一帧（8字节）
 *
 * MCU主设备配置（需对齐）：
 *   Mode      : SPI_MODE_0 (CPOL=0, CPHA=0)
 *   Bits/Word : 8
 *   Speed     : 1 MHz
 *   发送数据   : {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08}
 *
 * 编译：aarch64-linux-gnu-gcc -o spi_slave_recv_loop spi_slave_recv_loop.c
 * 运行：./spi_slave_recv_loop
 * 退出：按 Ctrl+C
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>

/* ========== SPI配置（必须与MCU主设备完全一致）========== */
#define SPI_DEVICE      "/dev/spidev4.0"
#define SPI_MODE        SPI_MODE_2      /* CPOL=1, CPHA=1 */
#define SPI_BITS        8
#define SPI_SPEED       1000000         /* 1MHz */
#define FRAME_LEN       128              /* 每帧256字节 */
/* ===================================================== */

static volatile int keep_running = 1;

static int is_all_zero(const uint8_t *buf, int len) {
    for (int i = 0; i < len; i++)
        if (buf[i] != 0)
            return 0;
    return 1;
}

void sigint_handler(int sig) {
    (void)sig;
    keep_running = 0;
    printf("\n[INFO] User interrupted, exiting...\n");
}

int main(void)
{
    uint8_t rx_buf[FRAME_LEN];
    uint8_t tx_buf[FRAME_LEN] = {0xAA, 0xBB, 0xCC, 0xDD};
    tx_buf[FRAME_LEN-4] = 0x11;
    tx_buf[FRAME_LEN-3] = 0x22;
    tx_buf[FRAME_LEN-2] = 0x33;
    tx_buf[FRAME_LEN-1] = 0x44;

    int fd, ret;
    unsigned int frame_count = 0;

    /* 注册退出信号 */
    signal(SIGINT, sigint_handler);

    /* 1. 打开 SPI 设备 */
    fd = open(SPI_DEVICE, O_RDWR);
    if (fd < 0) {
        perror("open " SPI_DEVICE);
        return 1;
    }

    /* 2. 配置 SPI 模式 */
    uint8_t mode = SPI_MODE;
	mode |= SPI_LSB_FIRST;
    ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
    if (ret == -1) {
        perror("SPI_IOC_WR_MODE");
        close(fd);
        return 1;
    }

    /* 3. 配置每字位数 */
    uint8_t bits = SPI_BITS;
    ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
    if (ret == -1) {
        perror("SPI_IOC_WR_BITS_PER_WORD");
        close(fd);
        return 1;
    }

    /* 4. 配置最大时钟频率 */
    uint32_t speed = SPI_SPEED;
    ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
    if (ret == -1) {
        perror("SPI_IOC_WR_MAX_SPEED_HZ");
        close(fd);
        return 1;
    }

    /* 5. 回读验证配置 */
    ioctl(fd, SPI_IOC_RD_MODE, &mode);
    ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
    ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);

    printf("========================================\n");
    printf("SPI Slave Config (aligned with MCU)\n");
    printf("========================================\n");
    printf("Device      : %s\n", SPI_DEVICE);
    printf("Mode        : %d (CPOL=%d, CPHA=%d)\n",
           mode, (mode & SPI_CPOL) ? 1 : 0, (mode & SPI_CPHA) ? 1 : 0);
    printf("Bits/Word   : %d\n", bits);
    printf("Max Speed   : %d Hz\n", speed);
    printf("Frame length: %d bytes\n", FRAME_LEN);
    printf("========================================\n");
    printf("Waiting for MCU (master) to send data...\n");
    printf("Press Ctrl+C to stop.\n\n");

    /* 6. 循环接收数据 */
    while (keep_running) {
        memset(rx_buf, 0, FRAME_LEN);

        struct spi_ioc_transfer tr = {
            .tx_buf        = (unsigned long)tx_buf,
            .rx_buf        = (unsigned long)rx_buf,
            .len           = FRAME_LEN,
            .speed_hz      = SPI_SPEED,
            .bits_per_word = SPI_BITS,
        };
        ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
        if (ret < 0) {
            perror("spi transfer");
            break;
        }
        ret = FRAME_LEN;  /* transfer 成功则返回 FRAME_LEN */

        frame_count++;

        /* 只有 tx 或 rx 数据不全为零时才打印 */
        if (is_all_zero(tx_buf, FRAME_LEN) && is_all_zero(rx_buf, FRAME_LEN))
            continue;

        printf("\n========== Frame #%u (%d bytes) ==========\n", frame_count, ret);

        if (!is_all_zero(tx_buf, FRAME_LEN)) {
            printf("TX HEX: ");
            for (int i = 0; i < ret; i++)
                printf("0x%02X ", tx_buf[i]);
            printf("\n");
        }

        if (!is_all_zero(rx_buf, FRAME_LEN)) {
            printf("RX HEX: ");
            for (int i = 0; i < ret; i++)
                printf("0x%02X ", rx_buf[i]);
            printf("\n");
        }

        printf("=========================================\n");
    }

    close(fd);
    return 0;
}