// 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 <[email protected]> Copyright (C) 2003 Greg Kroah-Hartman <[email protected]> */ /* 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 <[email protected]> */ #define pr_fmt(fmt) … #include <linux/cdev.h> #include <linux/compat.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> /* * 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 { … }; #define I2C_MINORS … static LIST_HEAD(i2c_dev_list); static DEFINE_SPINLOCK(i2c_dev_list_lock); static struct i2c_dev *i2c_dev_get_by_minor(unsigned index) { … } static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap) { … } static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev) { … } static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf) { … } static DEVICE_ATTR_RO(name); static struct attribute *i2c_attrs[] = …; ATTRIBUTE_GROUPS(…); /* ------------------------------------------------------------------------- */ /* * After opening an instance of this character special file, a file * descriptor starts out associated only with an i2c_adapter (and bus). * * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg * traffic to any devices on the bus used by that adapter. That's because * the i2c_msg vectors embed all the addressing information they need, and * are submitted directly to an i2c_adapter. However, SMBus-only adapters * don't support that interface. * * To use read()/write() system calls on that file descriptor, or to use * SMBus interfaces (and work with SMBus-only hosts!), you must first issue * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous * (never registered) i2c_client so it holds the addressing information * needed by those system calls and by this SMBus interface. */ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count, loff_t *offset) { … } static ssize_t i2cdev_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) { … } static int i2cdev_check(struct device *dev, void *addrp) { … } /* walk up mux tree */ static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr) { … } /* recurse down mux tree */ static int i2cdev_check_mux_children(struct device *dev, void *addrp) { … } /* This address checking function differs from the one in i2c-core in that it considers an address with a registered device, but no driver bound to it, as NOT busy. */ static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr) { … } static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client, unsigned nmsgs, struct i2c_msg *msgs) { … } static noinline int i2cdev_ioctl_smbus(struct i2c_client *client, u8 read_write, u8 command, u32 size, union i2c_smbus_data __user *data) { … } static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { … } #ifdef CONFIG_COMPAT struct i2c_smbus_ioctl_data32 { … }; struct i2c_msg32 { … }; struct i2c_rdwr_ioctl_data32 { … }; static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { … } #else #define compat_i2cdev_ioctl … #endif static int i2cdev_open(struct inode *inode, struct file *file) { … } static int i2cdev_release(struct inode *inode, struct file *file) { … } static const struct file_operations i2cdev_fops = …; /* ------------------------------------------------------------------------- */ static const struct class i2c_dev_class = …; static void i2cdev_dev_release(struct device *dev) { … } static int i2cdev_attach_adapter(struct device *dev) { … } static int i2cdev_detach_adapter(struct device *dev) { … } static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action, void *data) { … } static struct notifier_block i2cdev_notifier = …; /* ------------------------------------------------------------------------- */ static int __init i2c_dev_attach_adapter(struct device *dev, void *dummy) { … } static int __exit i2c_dev_detach_adapter(struct device *dev, void *dummy) { … } /* * module load/unload record keeping */ static int __init i2c_dev_init(void) { … } static void __exit i2c_dev_exit(void) { … } MODULE_AUTHOR(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; module_init(…) …; module_exit(i2c_dev_exit);
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