linux-imx

// SPDX-License-Identifier: GPL-2.0-or-later

/*

    i2c-dev.c - i2c-bus driver, char device interface

​

    Copyright (C) 1995-97 Simon G. Vogl

    Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>

    Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>

​

*/

​

/* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.

   But I have used so much of his original code and ideas that it seems

   only fair to recognize him as co-author -- Frodo */

​

/* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */

​

#include <linux/cdev.h>

#include <linux/device.h>

#include <linux/fs.h>

#include <linux/i2c-dev.h>

#include <linux/i2c.h>

#include <linux/init.h>

#include <linux/jiffies.h>

#include <linux/kernel.h>

#include <linux/list.h>

#include <linux/module.h>

#include <linux/notifier.h>

#include <linux/slab.h>

#include <linux/uaccess.h>

#include <linux/compat.h>

​

/*

 * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a

 * slave (i2c_client) with which messages will be exchanged.  It's coupled

 * with a character special file which is accessed by user mode drivers.

 *

 * The list of i2c_dev structures is parallel to the i2c_adapter lists

 * maintained by the driver model, and is updated using bus notifications.

 */

struct i2c_dev {

    struct list_head list;

    struct i2c_adapter *adap;

    struct device *dev;

    struct cdev cdev;

};

​

#define I2C_MINORS  (MINORMASK + 1)

static LIST_HEAD(i2c_dev_list);

static DEFINE_SPINLOCK(i2c_dev_list_lock);

​

static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)

{

    struct i2c_dev *i2c_dev;

​

    spin_lock(&i2c_dev_list_lock);

    list_for_each_entry(i2c_dev, &i2c_dev_list, list) {

        if (i2c_dev->adap->nr == index)

            goto found;

    }

    i2c_dev = NULL;

found:

    spin_unlock(&i2c_dev_list_lock);

    return i2c_dev;