利用driver 提供的debug接口 dump pmic register

写程序熟悉 练练手，利用PMIC提供debug接口，dump出来PMIC的寄存器的值

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

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

#define SUCCESSFULL             1
#define READ_ERROR -1
#define ARGS_ERROR -2
#define PAGE_SIZE               4

#define PMIC_START_ADDR         0x00
#define PMIC_END_ADDR           0xFF

#define PMIC_DEBUG_ADDR "/sys/kernel/pmic_debug/pmic_debug/addr"
#define PMIC_DEBUG_OPS "/sys/kernel/pmic_debug/pmic_debug/ops"
#define PMIC_DEBUG_DATA "/sys/kernel/pmic_debug/pmic_debug/data"

typedef struct {
        char *addr_path;
        char *ops_path;
        char *data_path;
        char *addr;
        char *data;
        char *ops;
} cmd_class;
static int _read(cmd_class cmd)
{
        int ret = 0;
        int addr_fd = -1;
        int data_fd = -1;
        int ops_fd = -1;

        addr_fd = open(cmd.addr_path, O_WRONLY);
        if (addr_fd < 0)
                return -1;
        ret = write(addr_fd, cmd.addr, sizeof(cmd.addr));
        if (ret < 0) {
                close(addr_fd);
                return -1;
        }
        close(addr_fd);

        ops_fd = open(cmd.ops_path, O_WRONLY);
        if (addr_fd < 0)
                return -1;
        ret = write(ops_fd, cmd.ops, sizeof(cmd.addr));
        if (ret < 0) {
                close(ops_fd);
                return -1;
        }
        close(ops_fd);

        data_fd = open(cmd.data_path, O_RDONLY);
        if (data_fd < 0)
                return -1;

        do {
                char *buff = malloc(4);
                ret = read(data_fd, buff, sizeof(PAGE_SIZE));
                strcpy(cmd.data, buff);
                cmd.data = cmd.data + ret;
        } while (ret != 0);

        close(data_fd);

        return ret;
}

static int _dump()
{
        int i = PMIC_START_ADDR, ret = SUCCESSFULL;

        printf("dump PMIC register:\n");
        for (; i <= PMIC_END_ADDR; ++i) {
                cmd_class cmd;

                cmd.addr_path = PMIC_DEBUG_ADDR;
                cmd.addr = malloc(6);
                sprintf(cmd.addr, "0x%02x", i);

                cmd.ops_path = PMIC_DEBUG_OPS;
                cmd.ops = malloc(5);
                cmd.ops = "read";

                cmd.data_path = PMIC_DEBUG_DATA;
                cmd.data = malloc(13);

                if (_read(cmd) == READ_ERROR) {
                        printf("_read():%d ERROR: - dump addr = %s faile\n", READ_ERROR, cmd.addr);
                        ret = READ_ERROR;
                        return ret;
                }
                printf("\taddr = %s   %s\n", cmd.addr, cmd.data);
        }
        return ret;
}
int main(char** argv, int argc)
{
        int ret = READ_ERROR;

        ret = _dump();

        return ret;
}

这里边碰见一个问题，在read data的时候开始总是只能读到4个字节，不知道为什么，后来看了看driver，发现driver这样写的
按照4字节往接口发送，结果read函数只能读到4个字节（然后有一个结束符？），最后只能通过while实现了。吐口水cat函数是不是也是while循环呢，估计没错

case PMIC_DBG_MASK:
                for (i = 0; i < valid; i++) {
                        buf_size = PAGE_SIZE - ret;
                        ret += snprintf(buf + ret, buf_size,
                                        pmic_msg_format[type],
                                        i, array[i]);
                }
                break;