pios_i2c.c

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/*
 * 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 3 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, see <http://www.gnu.org/licenses/>
 */

/* Project Includes */
#include <pios.h>
#include <pios_mutex.h>
#include <pios_i2c.h>
#include <pios_i2c_priv.h>

#if defined(PIOS_INCLUDE_I2C)

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>

#define PIOS_I2C_MAGIC 0x63324950       /* 'PI2c' */

struct pios_i2c_adapter {
        uint32_t magic;

        int fd;

        struct pios_mutex *lock;
};

int32_t PIOS_I2C_Init(pios_i2c_t *i2c_id, const char *path)
{
        struct pios_i2c_adapter *dev;

        dev = malloc(sizeof(*dev));

        if (dev == NULL) {
                return -1;
        }

        *dev = (struct pios_i2c_adapter) {
                .magic = PIOS_I2C_MAGIC,
        };

        dev->lock = PIOS_Mutex_Create();

        if (!dev->lock) {
                return -1;
        }
 
        dev->fd = open(path, O_RDWR);

        if (dev->fd < 0) {
                perror("i2c-open");
                return -2;
        }

        *i2c_id = dev;

        /* No error */
        return 0;
}

int32_t PIOS_I2C_Transfer(pios_i2c_t i2c_id, const struct pios_i2c_txn txn_list[], uint32_t num_txns)
{
        struct pios_i2c_adapter *dev = (struct pios_i2c_adapter *)i2c_id;

        int ret = 0;

        PIOS_Assert(dev->magic == PIOS_I2C_MAGIC);

        if (num_txns > 10) {
                return -1;
        }

        struct i2c_msg msgs[num_txns];

        for (int i = 0; i < num_txns; i++) {
                msgs[i].addr = txn_list[i].addr;
                if (txn_list[i].rw == PIOS_I2C_TXN_WRITE) {
                        msgs[i].flags = 0;
                } else {
                        msgs[i].flags = I2C_M_RD;
                }
                msgs[i].buf = txn_list[i].buf;
                msgs[i].len = txn_list[i].len;
        }

        struct i2c_rdwr_ioctl_data msgset = {
                .msgs = msgs,
                .nmsgs = num_txns
        };

        PIOS_Mutex_Lock(dev->lock, PIOS_MUTEX_TIMEOUT_MAX);

        if (ioctl(dev->fd, I2C_RDWR, &msgset) < 0) {
                perror("i2c-ioctl"); /* XXX remove */
                ret = -1;
        }

        PIOS_Mutex_Unlock(dev->lock);

        return ret;
}

#endif /* PIOS_INCLUDE_I2C */