/* ibmsetmax.c - */
/* based on setmax.c, http://www.cwi.nl/ftp/aeb/setmax.c */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/ioctl.h>
#include <linux/hdreg.h>

#ifndef HDIO_DRIVE_TASK
#define HDIO_DRIVE_TASK	0x031e
#endif

#define INITIALIZE_DRIVE_PARAMETERS 0x91
#define READ_NATIVE_MAX_ADDRESS 0xf8
#define CHECK_POWER_MODE	0xe5
#define SET_MAX			0xf9

#define LBA	0x40
#define VV	1		/* if set in sectorct then NOT volatile */

struct idecmdin {
	unsigned char cmd;
	unsigned char feature;
	unsigned char nsect;
	unsigned char sect, lcyl, hcyl;
	unsigned char select;
};

struct idecmdout {
	unsigned char status;
	unsigned char error;
	unsigned char nsect;
	unsigned char sect, lcyl, hcyl;
	unsigned char select;
};

unsigned int
tolba(unsigned char *args) {
	return ((args[6] & 0xf) << 24) + (args[5] << 16) + (args[4] << 8) + args[3];
}

void
fromlba(unsigned char *args, unsigned int lba) {
	args[3] = (lba & 0xff);
	lba >>= 8;
	args[4] = (lba & 0xff);
	lba >>= 8;
	args[5] = (lba & 0xff);
	lba >>= 8;
	args[6] = (args[6] & 0xf0) | (lba & 0xf);
}

void
get_identity(int fd) {
	unsigned char args[4+512] = {WIN_IDENTIFY,0,0,1,};
	struct hd_driveid *id = (struct hd_driveid *)&args[4];

	if (ioctl(fd, HDIO_DRIVE_CMD, &args)) {
		perror("HDIO_DRIVE_CMD");
		fprintf(stderr,
			"WIN_IDENTIFY failed - trying WIN_PIDENTIFY\n");
		args[0] = WIN_PIDENTIFY;
		if (ioctl(fd, HDIO_DRIVE_CMD, &args)) {
			perror("HDIO_DRIVE_CMD");
			fprintf(stderr,
			       "WIN_PIDENTIFY also failed - giving up\n");
			exit(1);
		}
	}

	printf("lba capacity: %d sectors (%lld bytes)\n",
	       id->lba_capacity,
	       (long long) id->lba_capacity * 512);
}

/*
 * result: in LBA mode precisely what is expected
 *         in CHS mode the correct H and S, and C mod 65536.
 */
unsigned int
get_native_max(int fd, int slave) {
	unsigned char args[7];
	int i;

	for (i=0; i<7; i++)
		args[i] = 0;
	args[0] = READ_NATIVE_MAX_ADDRESS;
	args[6] = (slave ? 0x10 : 0) | LBA;
	if (ioctl(fd, HDIO_DRIVE_TASK, &args)) {
		perror("HDIO_DRIVE_TASK failed READ_NATIVE_MAX_ADDRESS");
		for (i=0; i<7; i++)
			printf("%d = 0x%x\n", args[i], args[i]);
		exit(1);
	}
	return tolba(args);
}

void
set_max_address(int fd, int slave, int delta) {
	unsigned char args[7];
	int i, nativemax;

	nativemax = get_native_max(fd, slave);
	printf("nativemax=%d (0x%x)\n", nativemax, nativemax);

	for (i=0; i<7; i++)
		args[i] = 0;
	args[0] = SET_MAX;
	args[1] = 0;
        args[2] = 1; /* non-volatile */
	fromlba(args, delta-1);
	args[6] |= LBA;

	if (ioctl(fd, HDIO_DRIVE_TASK, &args)) {
		perror("HDIO_DRIVE_TASK failed SET_MAX");
		for (i=0; i<7; i++)
			printf("%d = 0x%x\n", args[i], args[i]);
		exit(1);
	}
}

static char short_opts[] = "m:";
static const struct option long_opts[] = {
	{ "max",	required_argument,	NULL,	'd' },
        { NULL, 0, NULL, 0 }
};

static char *usage_txt =
"Call: ibmsetmax [-m D] DEVICE\n"
"\n"
"The call  \"ibmsetmax -m D DEVICE\"  will do a SET_MAX command\n"
"to set the non-volatile maximum accessible sector number D sectors.\n"
"\n"
"The call  \"setmax DEVICE\"  will do a READ_NATIVE_MAX_ADDRESS\n"
"command, and report the maximum accessible sector number.\n"
"\n"
"This is IDE-only. Probably DEVICE is /dev/hdx for some x.\n\n";

int
main(int argc, char **argv){
	int fd, c;
	int delta;

	/* If you modify device, also update slave, if necessary. */
	/* master: hda, hdc, hde; slave: hdb, hdd, hdf */
	char *device = NULL;	/* e.g. "/dev/hda" */
	int slave = 0;

	delta = -1;
	while ((c = getopt_long (argc, argv, short_opts, long_opts, NULL)) != -1) {
		switch(c) {
		case 'm':
			delta = atoi(optarg);
			break;
		case '?':
		default:
			fprintf(stderr, "unknown option\n");
			fprintf(stderr, usage_txt);
			exit(1);
		}
	}

	if (optind < argc)
		device = argv[optind];
	if (!device) {
		fprintf(stderr, "no device specified - "
			"use e.g. \"setmax /dev/hdb\"\n");
		fprintf(stderr, usage_txt);
		exit(1);
	}
	printf("Using device %s\n", device);

	fd = open(device, O_RDONLY);
	if (fd == -1) {
		perror("open");
		exit(1);
	}

	if (delta != -1) {
		printf("setting delta=%d\n", delta);
		set_max_address(fd, slave, delta);
	} else {
		int mad = get_native_max(fd, slave);
		long long bytes = (long long) (mad+1) * 512;
		int hMB = (bytes+50000000)/100000000;

		printf("native max address: %d\n", mad);
		printf("that is %lld bytes, %d.%d GB\n",
		       bytes, hMB/10, hMB%10);
	}
	get_identity(fd);

	return 0;
}