Linux内核读取spi-nor flash sn

设备量产时，需要自动设置一个mac地址和sn，如果使用随机数生成的话，可能会有重复的，这里读取spi-nor的sn，参考sn来生成设备的mac和sn；

添加如下部分：

代码如下：

#include <linux/proc_fs.h>
static ssize_t unique_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
  struct spi_nor *nor = PDE_DATA(file_inode(file));
  u8      unique[12];
  u64         unique_id = 0;
  int     i, tmp;

  tmp = nor->read_reg(nor, 0x4b, unique, 12);
  if (tmp < 0) {
    dev_dbg(nor->dev, " error %d reading unique ID\n", tmp);
    return 0;
  }

  for (i=4; i<11; i++) {
    unique_id |= unique[i];
    unique_id = unique_id << 8;
  }
  unique_id |= unique[i];

  return sprintf(buf, "%llx\n", unique_id);
}

static const struct file_operations spi_nor_proc_fops = {
  .read   = unique_read,
  .llseek = default_llseek,
};


static const struct spi_device_id *spi_nor_read_id(struct spi_nor *nor)
{
  int     tmp;
  u8      id[5];
  u32     jedec;
  u16                     ext_jedec;
  struct flash_info *info;

  //调用
  proc_create_data("unique_id", 0666, NULL, &spi_nor_proc_fops, nor);


  tmp = nor->read_reg(nor, SPINOR_OP_RDID, id, 5);
  if (tmp < 0) {
    dev_dbg(nor->dev, " error %d reading JEDEC ID\n", tmp);
    return ERR_PTR(tmp);
  }
  jedec = id[0];
  jedec = jedec << 8;
  jedec |= id[1];
  jedec = jedec << 8;
  jedec |= id[2];

  ext_jedec = id[3] << 8 | id[4];

  for (tmp = 0; tmp < ARRAY_SIZE(spi_nor_ids) - 1; tmp++) {
    info = (void *)spi_nor_ids[tmp].driver_data;
    if (info->jedec_id == jedec) {
      if (info->ext_id == 0 || info->ext_id == ext_jedec)
        return &spi_nor_ids[tmp];
    }
  }
  dev_err(nor->dev, "unrecognized JEDEC id %06x\n", jedec);
  return ERR_PTR(-ENODEV);
}

然后应用层读取/proc/unique_id即可，应用层读取示例：

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>

#include <algorithm>
#include <string>

using namespace std;

int main(void)
{
    int fd;
    
    char  uid[32] = {0};
    int size;

    fd = open("/proc/unique_id", O_RDONLY);
    if (fd < 0)
        return 1;

    size = read(fd, uid, sizeof(uid));
    close(fd);
    
    uid[strlen(uid)-1] = '\0';
    
    //转为大写
    std::string str = uid;
    std::transform(str.begin(), str.end(),str.begin(), ::toupper);
    printf("%s", str.c_str());

    return 0;
}