root/i2c-tools/trunk/tools/i2cbusses.c

/*
    i2cbusses: Print the installed i2c busses for both 2.4 and 2.6 kernels.
               Part of user-space programs to access for I2C
               devices.
    Copyright (c) 1999-2003  Frodo Looijaard <frodol@dds.nl> and
                             Mark D. Studebaker <mdsxyz123@yahoo.com>
    Copyright (C) 2008       Jean Delvare <khali@linux-fr.org>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
    MA 02110-1301 USA.
*/

/* For strdup */
#define _BSD_SOURCE 1

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>  /* for NAME_MAX */
#include <string.h>
#include <strings.h>    /* for strcasecmp() */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <dirent.h>
#include <fcntl.h>
#include <errno.h>
#include "i2cbusses.h"
#include <linux/i2c-dev.h>

enum adt { adt_dummy, adt_isa, adt_i2c, adt_smbus, adt_unknown };

struct adap_type {
        const char *funcs;
        const char* algo;
};

static struct adap_type adap_types[5] = {
        { .funcs        = "dummy",
          .algo         = "Dummy bus", },
        { .funcs        = "isa",
          .algo         = "ISA bus", },
        { .funcs        = "i2c",
          .algo         = "I2C adapter", },
        { .funcs        = "smbus",
          .algo         = "SMBus adapter", },
        { .funcs        = "unknown",
          .algo         = "N/A", },
};

static enum adt i2c_get_funcs(int i2cbus)
{
        unsigned long funcs;
        int file;
        char filename[20];
        enum adt ret;

        file = open_i2c_dev(i2cbus, filename, 1);
        if (file < 0)
                return adt_unknown;

        if (ioctl(file, I2C_FUNCS, &funcs) < 0)
                ret = adt_unknown;
        else if (funcs & I2C_FUNC_I2C)
                ret = adt_i2c;
        else if (funcs & (I2C_FUNC_SMBUS_BYTE |
                          I2C_FUNC_SMBUS_BYTE_DATA |
                          I2C_FUNC_SMBUS_WORD_DATA))
                ret = adt_smbus;
        else
                ret = adt_dummy;

        close(file);
        return ret;
}

/* Remove trailing spaces from a string
   Return the new string length including the trailing NUL */
static int rtrim(char *s)
{
        int i;

        for (i = strlen(s) - 1; i >= 0 && (s[i] == ' ' || s[i] == '\n'); i--)
                s[i] = '\0';
        return i + 2;
}

void free_adapters(struct i2c_adap *adapters)
{
        int i;

        for (i = 0; adapters[i].name; i++)
                free(adapters[i].name);
        free(adapters);
}

/* We allocate space for the adapters in bunches. The last item is a
   terminator, so here we start with room for 7 adapters, which should
   be enough in most cases. If not, we allocate more later as needed. */
#define BUNCH   8

/* n must match the size of adapters at calling time */
static struct i2c_adap *more_adapters(struct i2c_adap *adapters, int n)
{
        struct i2c_adap *new_adapters;

        new_adapters = realloc(adapters, (n + BUNCH) * sizeof(struct i2c_adap));
        if (!new_adapters) {
                free_adapters(adapters);
                return NULL;
        }
        memset(new_adapters + n, 0, BUNCH * sizeof(struct i2c_adap));

        return new_adapters;
}

struct i2c_adap *gather_i2c_busses(void)
{
        char s[120];
        struct dirent *de, *dde;
        DIR *dir, *ddir;
        FILE *f;
        char fstype[NAME_MAX], sysfs[NAME_MAX], n[NAME_MAX];
        int foundsysfs = 0;
        int count=0;
        struct i2c_adap *adapters;

        adapters = calloc(BUNCH, sizeof(struct i2c_adap));
        if (!adapters)
                return NULL;

        /* look in /proc/bus/i2c */
        if ((f = fopen("/proc/bus/i2c", "r"))) {
                while (fgets(s, 120, f)) {
                        char *algo, *name, *type, *all;
                        int len_algo, len_name, len_type;
                        int i2cbus;

                        algo = strrchr(s, '\t');
                        *(algo++) = '\0';
                        len_algo = rtrim(algo);

                        name = strrchr(s, '\t');
                        *(name++) = '\0';
                        len_name = rtrim(name);

                        type = strrchr(s, '\t');
                        *(type++) = '\0';
                        len_type = rtrim(type);

                        sscanf(s, "i2c-%d", &i2cbus);

                        if ((count + 1) % BUNCH == 0) {
                                /* We need more space */
                                adapters = more_adapters(adapters, count + 1);
                                if (!adapters)
                                        return NULL;
                        }

                        all = malloc(len_name + len_type + len_algo);
                        if (all == NULL) {
                                free_adapters(adapters);
                                return NULL;
                        }
                        adapters[count].nr = i2cbus;
                        adapters[count].name = strcpy(all, name);
                        adapters[count].funcs = strcpy(all + len_name, type);
                        adapters[count].algo = strcpy(all + len_name + len_type,
                                                      algo);
                        count++;
                }
                fclose(f);
                goto done;
        }

        /* look in sysfs */
        /* First figure out where sysfs was mounted */
        if ((f = fopen("/proc/mounts", "r")) == NULL) {
                goto done;
        }
        while (fgets(n, NAME_MAX, f)) {
                sscanf(n, "%*[^ ] %[^ ] %[^ ] %*s\n", sysfs, fstype);
                if (strcasecmp(fstype, "sysfs") == 0) {
                        foundsysfs++;
                        break;
                }
        }
        fclose(f);
        if (! foundsysfs) {
                goto done;
        }

        /* Bus numbers in i2c-adapter don't necessarily match those in
           i2c-dev and what we really care about are the i2c-dev numbers.
           Unfortunately the names are harder to get in i2c-dev */
        strcat(sysfs, "/class/i2c-dev");
        if(!(dir = opendir(sysfs)))
                goto done;
        /* go through the busses */
        while ((de = readdir(dir)) != NULL) {
                if (!strcmp(de->d_name, "."))
                        continue;
                if (!strcmp(de->d_name, ".."))
                        continue;

                /* this should work for kernels 2.6.5 or higher and */
                /* is preferred because is unambiguous */
                sprintf(n, "%s/%s/name", sysfs, de->d_name);
                f = fopen(n, "r");
                /* this seems to work for ISA */
                if(f == NULL) {
                        sprintf(n, "%s/%s/device/name", sysfs, de->d_name);
                        f = fopen(n, "r");
                }
                /* non-ISA is much harder */
                /* and this won't find the correct bus name if a driver
                   has more than one bus */
                if(f == NULL) {
                        sprintf(n, "%s/%s/device", sysfs, de->d_name);
                        if(!(ddir = opendir(n)))
                                continue;
                        while ((dde = readdir(ddir)) != NULL) {
                                if (!strcmp(dde->d_name, "."))
                                        continue;
                                if (!strcmp(dde->d_name, ".."))
                                        continue;
                                if ((!strncmp(dde->d_name, "i2c-", 4))) {
                                        sprintf(n, "%s/%s/device/%s/name",
                                                sysfs, de->d_name, dde->d_name);
                                        if((f = fopen(n, "r")))
                                                goto found;
                                }
                        }
                }

found:
                if (f != NULL) {
                        int i2cbus;
                        enum adt type;
                        char *px;

                        px = fgets(s, 120, f);
                        fclose(f);
                        if (!px) {
                                fprintf(stderr, "%s: read error\n", n);
                                continue;
                        }
                        if ((px = strchr(s, '\n')) != NULL)
                                *px = 0;
                        if (!sscanf(de->d_name, "i2c-%d", &i2cbus))
                                continue;
                        if (!strncmp(s, "ISA ", 4)) {
                                type = adt_isa;
                        } else {
                                /* Attempt to probe for adapter capabilities */
                                type = i2c_get_funcs(i2cbus);
                        }

                        if ((count + 1) % BUNCH == 0) {
                                /* We need more space */
                                adapters = more_adapters(adapters, count + 1);
                                if (!adapters)
                                        return NULL;
                        }

                        adapters[count].nr = i2cbus;
                        adapters[count].name = strdup(s);
                        if (adapters[count].name == NULL) {
                                free_adapters(adapters);
                                return NULL;
                        }
                        adapters[count].funcs = adap_types[type].funcs;
                        adapters[count].algo = adap_types[type].algo;
                        count++;
                }
        }
        closedir(dir);

done:
        return adapters;
}

static int lookup_i2c_bus_by_name(const char *bus_name)
{
        struct i2c_adap *adapters;
        int i, i2cbus = -1;

        adapters = gather_i2c_busses();
        if (adapters == NULL) {
                fprintf(stderr, "Error: Out of memory!\n");
                return -3;
        }

        /* Walk the list of i2c busses, looking for the one with the
           right name */
        for (i = 0; adapters[i].name; i++) {
                if (strcmp(adapters[i].name, bus_name) == 0) {
                        if (i2cbus >= 0) {
                                fprintf(stderr,
                                        "Error: I2C bus name is not unique!\n");
                                i2cbus = -4;
                                goto done;
                        }
                        i2cbus = adapters[i].nr;
                }
        }

        if (i2cbus == -1)
                fprintf(stderr, "Error: I2C bus name doesn't match any "
                        "bus present!\n");

done:
        free_adapters(adapters);
        return i2cbus;
}

/*
 * Parse an I2CBUS command line argument and return the corresponding
 * bus number, or a negative value if the bus is invalid.
 */
int lookup_i2c_bus(const char *i2cbus_arg)
{
        long i2cbus;
        char *end;

        i2cbus = strtol(i2cbus_arg, &end, 0);
        if (*end || !*i2cbus_arg) {
                /* Not a number, maybe a name? */
                return lookup_i2c_bus_by_name(i2cbus_arg);
        }
        if (i2cbus < 0 || i2cbus > 0xff) {
                fprintf(stderr, "Error: I2C bus out of range (0-255)!\n");
                return -2;
        }

        return i2cbus;
}

/*
 * Parse a CHIP-ADDRESS command line argument and return the corresponding
 * chip address, or a negative value if the address is invalid.
 */
int parse_i2c_address(const char *address_arg)
{
        long address;
        char *end;

        address = strtol(address_arg, &end, 0);
        if (*end || !*address_arg) {
                fprintf(stderr, "Error: Chip address is not a number!\n");
                return -1;
        }
        if (address < 0x03 || address > 0x77) {
                fprintf(stderr, "Error: Chip address out of range "
                        "(0x03-0x77)!\n");
                return -2;
        }

        return address;
}

int open_i2c_dev(const int i2cbus, char *filename, const int quiet)
{
        int file;

        sprintf(filename, "/dev/i2c/%d", i2cbus);
        file = open(filename, O_RDWR);

        if (file < 0 && errno == ENOENT) {
                sprintf(filename, "/dev/i2c-%d", i2cbus);
                file = open(filename, O_RDWR);
        }

        if (file < 0 && !quiet) {
                if (errno == ENOENT) {
                        fprintf(stderr, "Error: Could not open file "
                                "`/dev/i2c-%d' or `/dev/i2c/%d': %s\n",
                                i2cbus, i2cbus, strerror(ENOENT));
                } else {
                        fprintf(stderr, "Error: Could not open file "
                                "`%s': %s\n", filename, strerror(errno));
                        if (errno == EACCES)
                                fprintf(stderr, "Run as root?\n");
                }
        }

        return file;
}

int set_slave_addr(int file, int address, int force)
{
        /* With force, let the user read from/write to the registers
           even when a driver is also running */
        if (ioctl(file, force ? I2C_SLAVE_FORCE : I2C_SLAVE, address) < 0) {
                fprintf(stderr,
                        "Error: Could not set address to 0x%02x: %s\n",
                        address, strerror(errno));
                return -errno;
        }

        return 0;
}