using MDIO to access PHY registers

mdio_reg.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/mii.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/sockios.h>
#include <linux/types.h>
#include <netinet/in.h>

#define reteck(ret) \
	if (ret < 0) {\
		printf("%m! \"%s\" : line: %d\n", __func__, __LINE__);\
		goto lab; \
	}

#define help() \
	printf("mdio_reg:\n");\
	printf("read operation: mdio_reg reg_addr\n");\
	printf("write operation: mdio_reg reg_addr value\n");\
	printf("For example:\n");\
	printf("mdio_reg eth0 1\n");\
	printf("mdio_reg eth0 0 0x12\n\n");\
	exit(0)

int sockfd;

int main(int argc, char *argv[])
{
	if (argc == 1 || !strcmp(argv[1], "-h"))
	{
		help();
	}
	struct mii_ioctl_data *mii = NULL;
	struct ifreq ifr;
	int ret;

	memset(&ifr, 0, sizeof(ifr));
	strncpy(ifr.ifr_name, argv[1], IFNAMSIZ - 1);
	sockfd = socket(PF_LOCAL, SOCK_DGRAM, 0);
	reteck(sockfd);
	ret = ioctl(sockfd, SIOCGMIIPHY, &ifr);
	reteck(ret);
	mii = (struct mii_ioctl_data*)&ifr.ifr_data;

	if (argc == 3) {
		mii->reg_num = (uint16_t) strtoul(argv[2], NULL, 0);
		ret = ioctl(sockfd, SIOCGMIIREG, &ifr);
		reteck(ret);
		printf("read phy addr: 0x%x reg: 0x%x value: 0x%x\n",
			mii->phy_id, mii->reg_num, mii->val_out);
	}
	else if (argc == 4) {
		mii->reg_num = (uint16_t) strtoul(argv[2], NULL, 0);
		mii->val_in = (uint16_t) strtoul(argv[3], NULL, 0);
		ret = ioctl(sockfd, SIOCGMIIREG, &ifr);
		reteck(ret);
		printf("write phy addr: 0x%x reg: 0x%x value: 0x%x\n",
			mii->phy_id, mii->reg_num, mii->val_in);
	}
lab:
	close(sockfd);
	return 0;
}