comedi_fops.c - Android社区 - https://www.androidos.net.cn/

Kernel | 4.1

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/*
 * comedi/comedi_fops.c
 * comedi kernel module
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include "comedi_compat32.h"

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include "comedidev.h"
#include <linux/cdev.h>
#include <linux/stat.h>

#include <linux/io.h>
#include <linux/uaccess.h>

#include "comedi_internal.h"

/**
 * struct comedi_file - per-file private data for comedi device
 * @dev: comedi_device struct
 * @read_subdev: current "read" subdevice
 * @write_subdev: current "write" subdevice
 * @last_detach_count: last known detach count
 * @last_attached: last known attached/detached state
 */
struct comedi_file {
	struct comedi_device *dev;
	struct comedi_subdevice *read_subdev;
	struct comedi_subdevice *write_subdev;
	unsigned int last_detach_count;
	bool last_attached:1;
};

#define COMEDI_NUM_MINORS 0x100
#define COMEDI_NUM_SUBDEVICE_MINORS	\
	(COMEDI_NUM_MINORS - COMEDI_NUM_BOARD_MINORS)

static int comedi_num_legacy_minors;
module_param(comedi_num_legacy_minors, int, S_IRUGO);
MODULE_PARM_DESC(comedi_num_legacy_minors,
		 "number of comedi minor devices to reserve for non-auto-configured devices (default 0)"
		);

unsigned int comedi_default_buf_size_kb = CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB;
module_param(comedi_default_buf_size_kb, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(comedi_default_buf_size_kb,
		 "default asynchronous buffer size in KiB (default "
		 __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB) ")");

unsigned int comedi_default_buf_maxsize_kb
	= CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB;
module_param(comedi_default_buf_maxsize_kb, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(comedi_default_buf_maxsize_kb,
		 "default maximum size of asynchronous buffer in KiB (default "
		 __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB) ")");

static DEFINE_MUTEX(comedi_board_minor_table_lock);
static struct comedi_device
*comedi_board_minor_table[COMEDI_NUM_BOARD_MINORS];

static DEFINE_MUTEX(comedi_subdevice_minor_table_lock);
/* Note: indexed by minor - COMEDI_NUM_BOARD_MINORS. */
static struct comedi_subdevice
*comedi_subdevice_minor_table[COMEDI_NUM_SUBDEVICE_MINORS];

static struct class *comedi_class;
static struct cdev comedi_cdev;

static void comedi_device_init(struct comedi_device *dev)
{
	kref_init(&dev->refcount);
	spin_lock_init(&dev->spinlock);
	mutex_init(&dev->mutex);
	init_rwsem(&dev->attach_lock);
	dev->minor = -1;
}

static void comedi_dev_kref_release(struct kref *kref)
{
	struct comedi_device *dev =
		container_of(kref, struct comedi_device, refcount);

mutex_destroy(&dev->mutex);
	put_device(dev->class_dev);
	kfree(dev);
}

/**
 * comedi_dev_put - release a use of a comedi device structure
 * @dev: comedi_device struct
 *
 * Must be called when a user of a comedi device is finished with it.
 * When the last user of the comedi device calls this function, the
 * comedi device is destroyed.
 *
 * Return 1 if the comedi device is destroyed by this call or dev is
 * NULL, otherwise return 0.  Callers must not assume the comedi
 * device is still valid if this function returns 0.
 */
int comedi_dev_put(struct comedi_device *dev)
{
	if (dev)
		return kref_put(&dev->refcount, comedi_dev_kref_release);
	return 1;
}
EXPORT_SYMBOL_GPL(comedi_dev_put);

static struct comedi_device *comedi_dev_get(struct comedi_device *dev)
{
	if (dev)
		kref_get(&dev->refcount);
	return dev;
}

static void comedi_device_cleanup(struct comedi_device *dev)
{
	struct module *driver_module = NULL;

if (!dev)
		return;
	mutex_lock(&dev->mutex);
	if (dev->attached)
		driver_module = dev->driver->module;
	comedi_device_detach(dev);
	if (driver_module && dev->use_count)
		module_put(driver_module);
	mutex_unlock(&dev->mutex);
}

static bool comedi_clear_board_dev(struct comedi_device *dev)
{
	unsigned int i = dev->minor;
	bool cleared = false;

mutex_lock(&comedi_board_minor_table_lock);
	if (dev == comedi_board_minor_table[i]) {
		comedi_board_minor_table[i] = NULL;
		cleared = true;
	}
	mutex_unlock(&comedi_board_minor_table_lock);
	return cleared;
}

static struct comedi_device *comedi_clear_board_minor(unsigned minor)
{
	struct comedi_device *dev;

mutex_lock(&comedi_board_minor_table_lock);
	dev = comedi_board_minor_table[minor];
	comedi_board_minor_table[minor] = NULL;
	mutex_unlock(&comedi_board_minor_table_lock);
	return dev;
}

static void comedi_free_board_dev(struct comedi_device *dev)
{
	if (dev) {
		comedi_device_cleanup(dev);
		if (dev->class_dev) {
			device_destroy(comedi_class,
				       MKDEV(COMEDI_MAJOR, dev->minor));
		}
		comedi_dev_put(dev);
	}
}

static struct comedi_subdevice
*comedi_subdevice_from_minor(const struct comedi_device *dev, unsigned minor)
{
	struct comedi_subdevice *s;
	unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;

BUG_ON(i >= COMEDI_NUM_SUBDEVICE_MINORS);
	mutex_lock(&comedi_subdevice_minor_table_lock);
	s = comedi_subdevice_minor_table[i];
	if (s && s->device != dev)
		s = NULL;
	mutex_unlock(&comedi_subdevice_minor_table_lock);
	return s;
}

static struct comedi_device *comedi_dev_get_from_board_minor(unsigned minor)
{
	struct comedi_device *dev;

BUG_ON(minor >= COMEDI_NUM_BOARD_MINORS);
	mutex_lock(&comedi_board_minor_table_lock);
	dev = comedi_dev_get(comedi_board_minor_table[minor]);
	mutex_unlock(&comedi_board_minor_table_lock);
	return dev;
}

static struct comedi_device *comedi_dev_get_from_subdevice_minor(unsigned minor)
{
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;

BUG_ON(i >= COMEDI_NUM_SUBDEVICE_MINORS);
	mutex_lock(&comedi_subdevice_minor_table_lock);
	s = comedi_subdevice_minor_table[i];
	dev = comedi_dev_get(s ? s->device : NULL);
	mutex_unlock(&comedi_subdevice_minor_table_lock);
	return dev;
}

/**
 * comedi_dev_get_from_minor - get comedi device by minor device number
 * @minor: minor device number
 *
 * Finds the comedi device associated by the minor device number, if any,
 * and increments its reference count.  The comedi device is prevented from
 * being freed until a matching call is made to comedi_dev_put().
 *
 * Return a pointer to the comedi device if it exists, with its usage
 * reference incremented.  Return NULL if no comedi device exists with the
 * specified minor device number.
 */
struct comedi_device *comedi_dev_get_from_minor(unsigned minor)
{
	if (minor < COMEDI_NUM_BOARD_MINORS)
		return comedi_dev_get_from_board_minor(minor);

return comedi_dev_get_from_subdevice_minor(minor);
}
EXPORT_SYMBOL_GPL(comedi_dev_get_from_minor);

static struct comedi_subdevice *
comedi_read_subdevice(const struct comedi_device *dev, unsigned int minor)
{
	struct comedi_subdevice *s;

if (minor >= COMEDI_NUM_BOARD_MINORS) {
		s = comedi_subdevice_from_minor(dev, minor);
		if (!s || (s->subdev_flags & SDF_CMD_READ))
			return s;
	}
	return dev->read_subdev;
}

static struct comedi_subdevice *
comedi_write_subdevice(const struct comedi_device *dev, unsigned int minor)
{
	struct comedi_subdevice *s;

if (minor >= COMEDI_NUM_BOARD_MINORS) {
		s = comedi_subdevice_from_minor(dev, minor);
		if (!s || (s->subdev_flags & SDF_CMD_WRITE))
			return s;
	}
	return dev->write_subdev;
}

static void comedi_file_reset(struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_subdevice *s, *read_s, *write_s;
	unsigned int minor = iminor(file_inode(file));

read_s = dev->read_subdev;
	write_s = dev->write_subdev;
	if (minor >= COMEDI_NUM_BOARD_MINORS) {
		s = comedi_subdevice_from_minor(dev, minor);
		if (!s || s->subdev_flags & SDF_CMD_READ)
			read_s = s;
		if (!s || s->subdev_flags & SDF_CMD_WRITE)
			write_s = s;
	}
	cfp->last_attached = dev->attached;
	cfp->last_detach_count = dev->detach_count;
	ACCESS_ONCE(cfp->read_subdev) = read_s;
	ACCESS_ONCE(cfp->write_subdev) = write_s;
}

static void comedi_file_check(struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;

if (cfp->last_attached != dev->attached ||
	    cfp->last_detach_count != dev->detach_count)
		comedi_file_reset(file);
}

static struct comedi_subdevice *comedi_file_read_subdevice(struct file *file)
{
	struct comedi_file *cfp = file->private_data;

comedi_file_check(file);
	return ACCESS_ONCE(cfp->read_subdev);
}

static struct comedi_subdevice *comedi_file_write_subdevice(struct file *file)
{
	struct comedi_file *cfp = file->private_data;

comedi_file_check(file);
	return ACCESS_ONCE(cfp->write_subdev);
}

static int resize_async_buffer(struct comedi_device *dev,
			       struct comedi_subdevice *s, unsigned new_size)
{
	struct comedi_async *async = s->async;
	int retval;

if (new_size > async->max_bufsize)
		return -EPERM;

if (s->busy) {
		dev_dbg(dev->class_dev,
			"subdevice is busy, cannot resize buffer\n");
		return -EBUSY;
	}
	if (comedi_buf_is_mmapped(s)) {
		dev_dbg(dev->class_dev,
			"subdevice is mmapped, cannot resize buffer\n");
		return -EBUSY;
	}

/* make sure buffer is an integral number of pages (we round up) */
	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;

retval = comedi_buf_alloc(dev, s, new_size);
	if (retval < 0)
		return retval;

if (s->buf_change) {
		retval = s->buf_change(dev, s);
		if (retval < 0)
			return retval;
	}

dev_dbg(dev->class_dev, "subd %d buffer resized to %i bytes\n",
		s->index, async->prealloc_bufsz);
	return 0;
}

/* sysfs attribute files */

static ssize_t max_read_buffer_kb_show(struct device *csdev,
				       struct device_attribute *attr, char *buf)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size = 0;