/* $NetBSD: i2cscan.c,v 1.5 2015/11/26 17:31:56 hubertf Exp $ */

/*-
 * Copyright (c) 2011, 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Paul Goyette and Jared McNeill
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: i2cscan.c,v 1.5 2015/11/26 17:31:56 hubertf Exp $");

#include <sys/types.h>
#include <sys/ioctl.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <dev/i2c/i2c_io.h>

#define MODE_DEFAULT 0
#define MODE_READ 1

__dead static void
usage(void)
{
        fprintf(stderr, "usage: %s [-r] i2cdev\n", getprogname());
        exit(EXIT_FAILURE);
}

static int
iic_smbus_quick_write(int fd, i2c_addr_t addr, int flags)
{
        i2c_ioctl_exec_t iie;

        iie.iie_op = I2C_OP_WRITE_WITH_STOP;
        iie.iie_addr = addr;
        iie.iie_cmd = NULL;
        iie.iie_cmdlen = 0;
        iie.iie_buf = NULL;
        iie.iie_buflen = 0;

        if (ioctl(fd, I2C_IOCTL_EXEC, &iie) == -1)
                return errno;
        return 0;
}

static int
iic_smbus_receive_byte(int fd, i2c_addr_t addr, uint8_t *valp, int flags)
{
        i2c_ioctl_exec_t iie;

        iie.iie_op = I2C_OP_READ_WITH_STOP;
        iie.iie_addr = addr;
        iie.iie_cmd = NULL;
        iie.iie_cmdlen = 0;
        iie.iie_buf = valp;
        iie.iie_buflen = 1;

        if (ioctl(fd, I2C_IOCTL_EXEC, &iie) == -1)
                return errno;
        return 0;
        
}

static void
do_i2c_scan(const char *dname, int fd, int mode)
{
        int error;
        int found = 0;
        i2c_addr_t addr;
        uint8_t val;

        for (addr = 0x09; addr < 0x78; addr++) {
                /*
                 * Skip certain i2c addresses:
                 *      0x00            General Call / START
                 *      0x01            CBUS Address
                 *      0x02            Different Bus format
                 *      0x03 - 0x07     Reserved
                 *      0x08            Host Address
                 *      0x0c            Alert Response Address
                 *      0x28            ACCESS.Bus host
                 *      0x37            ACCESS.Bus default address
                 *      0x48 - 0x4b     Prototypes
                 *      0x61            Device Default Address
                 *      0x78 - 0x7b     10-bit addresses
                 *      0x7c - 0x7f     Reserved
                 *
                 * Some of these are skipped by judicious selection
                 * of the range of the above for (;;) statement.
                 *
                 * if (addr <= 0x08 || addr >= 0x78)
                 *      continue;
                 */
                if (addr == 0x0c || addr == 0x28 || addr == 0x37 ||
                    addr == 0x61 || (addr & 0x7c) == 0x48)
                        continue;

                /*
                 * Use SMBus quick_write command to detect most
                 * addresses;  should avoid hanging the bus on
                 * some write-only devices (like clocks that show
                 * up at address 0x69)
                 *
                 * XXX The quick_write() is allegedly known to
                 * XXX corrupt the Atmel AT24RF08 EEPROM found
                 * XXX on some IBM Thinkpads!
                 */
                printf("\r%s: scanning 0x%02x", dname, addr);
                fflush(stdout);
                if ((addr & 0xf8) == 0x30 ||
                    (addr & 0xf0) == 0x50 ||
                    mode == MODE_READ)
                        error = iic_smbus_receive_byte(fd, addr, &val, 0);
                else
                        error = iic_smbus_quick_write(fd, addr, 0);
                if (error == 0) {
                        printf("\r%s: found device at 0x%02x\n",
                            dname, addr);
                        ++found;
                }
        }
        if (found == 0)
                printf("\r%s: no devices found\n", dname);
        else
                printf("\r%s: %d devices found\n", dname, found);
}

int
main(int argc, char *argv[])
{
        int fd;
        int ch, rflag;
        int mode;
        char *dev;
        char devn[32];

        setprogname(*argv);

        rflag = 0;

        while ((ch = getopt(argc, argv, "r")) != -1)
                switch (ch) {
                case 'r':
                        rflag = 1;
                        break;
                default:
                        break;
                }
        argv += optind;
        argc -= optind;

        if (rflag)
                mode = MODE_READ;
        else
                mode = MODE_DEFAULT;

        if (*argv == NULL)
                usage();
        dev = argv[0];

        if (strncmp(_PATH_DEV, dev, sizeof(_PATH_DEV) - 1)) {
                (void)snprintf(devn, sizeof(devn), "%s%s", _PATH_DEV, dev);
                dev = devn;
        }

        fd = open(dev, O_RDWR);
        if (fd == -1)
                err(EXIT_FAILURE, "couldn't open %s", *argv);

        do_i2c_scan(*argv, fd, mode);

        close(fd);

        return EXIT_SUCCESS;
}