text: /*
      module/drivers.c
      functions for manipulating drivers
  
      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.
  
      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., 675 Mass Ave, Cambridge, MA 02139, USA.
  
  */
  
  #define _GNU_SOURCE
  
  #define __NO_VERSION__
  #include "comedi_fops.h"
  #include <linux/device.h>
  #include <linux/module.h>
  #include <linux/pci.h>
  #include <linux/usb.h>
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/fcntl.h>
  #include <linux/delay.h>
  #include <linux/ioport.h>
  #include <linux/mm.h>
  #include <linux/slab.h>
  #include "comedidev.h"
  #include "wrapper.h"
  #include <linux/highmem.h>	/* for SuSE brokenness */
  #include <linux/vmalloc.h>
  #include <linux/cdev.h>
  #include <linux/dma-mapping.h>
  
  #include <linux/io.h>
  #include <asm/system.h>
  
  static int postconfig(struct comedi_device *dev);
  static int insn_rw_emulate_bits(struct comedi_device *dev,
  				struct comedi_subdevice *s,
  				struct comedi_insn *insn, unsigned int *data);
  static void *comedi_recognize(struct comedi_driver *driv, const char *name);
  static void comedi_report_boards(struct comedi_driver *driv);
  static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s);
  int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
  		     unsigned long new_size);
  
  struct comedi_driver *comedi_drivers;
  
  int comedi_modprobe(int minor)
  {
  	return -EINVAL;
  }
  
  static void cleanup_device(struct comedi_device *dev)
  {
  	int i;
  	struct comedi_subdevice *s;
  
  	if (dev->subdevices) {
  		for (i = 0; i < dev->n_subdevices; i++) {
  			s = dev->subdevices + i;
  			comedi_free_subdevice_minor(s);
  			if (s->async) {
  				comedi_buf_alloc(dev, s, 0);
  				kfree(s->async);
  			}
  		}
  		kfree(dev->subdevices);
  		dev->subdevices = NULL;
  		dev->n_subdevices = 0;
  	}
  	kfree(dev->private);
  	dev->private = NULL;
  	dev->driver = 0;
  	dev->board_name = NULL;
  	dev->board_ptr = NULL;
  	dev->iobase = 0;
  	dev->irq = 0;
  	dev->read_subdev = NULL;
  	dev->write_subdev = NULL;
  	dev->open = NULL;
  	dev->close = NULL;
  	comedi_set_hw_dev(dev, NULL);
  }
  
  static void __comedi_device_detach(struct comedi_device *dev)
  {
  	dev->attached = 0;
  	if (dev->driver)
  		dev->driver->detach(dev);
  	else
  		printk("BUG: dev->driver=NULL in comedi_device_detach()\n");
  	cleanup_device(dev);
  }
  
  void comedi_device_detach(struct comedi_device *dev)
  {
  	if (!dev->attached)
  		return;
  	__comedi_device_detach(dev);
  }
  
  int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
  {
  	struct comedi_driver *driv;
  	int ret;
  
  	if (dev->attached)
  		return -EBUSY;
  
  	for (driv = comedi_drivers; driv; driv = driv->next) {
  		if (!try_module_get(driv->module)) {
  			printk
  			    ("comedi: failed to increment module count, skipping\n");
  			continue;
  		}
  		if (driv->num_names) {
  			dev->board_ptr = comedi_recognize(driv, it->board_name);
  			if (dev->board_ptr == NULL) {
  				module_put(driv->module);
  				continue;
  			}
  		} else {
  			if (strcmp(driv->driver_name, it->board_name)) {
  				module_put(driv->module);
  				continue;
  			}
  		}
  		/* initialize dev->driver here so comedi_error() can be called from attach */
  		dev->driver = driv;
  		ret = driv->attach(dev, it);
  		if (ret < 0) {
  			module_put(dev->driver->module);
  			__comedi_device_detach(dev);
  			return ret;
  		}
  		goto attached;
  	}
  
  	/*  recognize has failed if we get here */
  	/*  report valid board names before returning error */
  	for (driv = comedi_drivers; driv; driv = driv->next) {
  		if (!try_module_get(driv->module)) {
  			printk("comedi: failed to increment module count\n");
  			continue;
  		}
  		comedi_report_boards(driv);
  		module_put(driv->module);
  	}
  	return -EIO;
  
  attached:
  	/* do a little post-config cleanup */
  	ret = postconfig(dev);
  	module_put(dev->driver->module);
  	if (ret < 0) {
  		__comedi_device_detach(dev);
  		return ret;
  	}
  
  	if (!dev->board_name) {
  		printk("BUG: dev->board_name=<%p>\n", dev->board_name);
  		dev->board_name = "BUG";
  	}
  	smp_wmb();
  	dev->attached = 1;
  
  	return 0;
  }
  
  int comedi_driver_register(struct comedi_driver *driver)
  {
  	driver->next = comedi_drivers;
  	comedi_drivers = driver;
  
  	return 0;
  }
  
  int comedi_driver_unregister(struct comedi_driver *driver)
  {
  	struct comedi_driver *prev;
  	int i;
  
  	/* check for devices using this driver */
  	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
  		struct comedi_device_file_info *dev_file_info =
  		    comedi_get_device_file_info(i);
  		struct comedi_device *dev;
  
  		if (dev_file_info == NULL)
  			continue;
  		dev = dev_file_info->device;
  
  		mutex_lock(&dev->mutex);
  		if (dev->attached && dev->driver == driver) {
  			if (dev->use_count)
  				printk
  				    ("BUG! detaching device with use_count=%d\n",
  				     dev->use_count);
  			comedi_device_detach(dev);
  		}
  		mutex_unlock(&dev->mutex);
  	}
  
  	if (comedi_drivers == driver) {
  		comedi_drivers = driver->next;
  		return 0;
  	}
  
  	for (prev = comedi_drivers; prev->next; prev = prev->next) {
  		if (prev->next == driver) {
  			prev->next = driver->next;
  			return 0;
  		}
  	}
  	return -EINVAL;
  }
  
  static int postconfig(struct comedi_device *dev)
  {
  	int i;
  	struct comedi_subdevice *s;
  	struct comedi_async *async = NULL;
  	int ret;
  
  	for (i = 0; i < dev->n_subdevices; i++) {
  		s = dev->subdevices + i;
  
  		if (s->type == COMEDI_SUBD_UNUSED)
  			continue;
  
  		if (s->len_chanlist == 0)
  			s->len_chanlist = 1;
  
  		if (s->do_cmd) {
  			BUG_ON((s->subdev_flags & (SDF_CMD_READ |
  						   SDF_CMD_WRITE)) == 0);
  			BUG_ON(!s->do_cmdtest);
  
  			async =
  			    kzalloc(sizeof(struct comedi_async), GFP_KERNEL);
  			if (async == NULL) {
  				printk("failed to allocate async struct\n");
  				return -ENOMEM;
  			}
  			init_waitqueue_head(&async->wait_head);
  			async->subdevice = s;
  			s->async = async;
  
  #define DEFAULT_BUF_MAXSIZE (64*1024)
  #define DEFAULT_BUF_SIZE (64*1024)
  
  			async->max_bufsize = DEFAULT_BUF_MAXSIZE;
  
  			async->prealloc_buf = NULL;
  			async->prealloc_bufsz = 0;
  			if (comedi_buf_alloc(dev, s, DEFAULT_BUF_SIZE) < 0) {
  				printk("Buffer allocation failed\n");
  				return -ENOMEM;
  			}
  			if (s->buf_change) {
  				ret = s->buf_change(dev, s, DEFAULT_BUF_SIZE);
  				if (ret < 0)
  					return ret;
  			}
  			comedi_alloc_subdevice_minor(dev, s);
  		}
  
  		if (!s->range_table && !s->range_table_list)
  			s->range_table = &range_unknown;
  
  		if (!s->insn_read && s->insn_bits)
  			s->insn_read = insn_rw_emulate_bits;
  		if (!s->insn_write && s->insn_bits)
  			s->insn_write = insn_rw_emulate_bits;
  
  		if (!s->insn_read)
  			s->insn_read = insn_inval;
  		if (!s->insn_write)
  			s->insn_write = insn_inval;
  		if (!s->insn_bits)
  			s->insn_bits = insn_inval;
  		if (!s->insn_config)
  			s->insn_config = insn_inval;
  
  		if (!s->poll)
  			s->poll = poll_invalid;
  	}
  
  	return 0;
  }
  
  /*  generic recognize function for drivers that register their supported board names */
  void *comedi_recognize(struct comedi_driver *driv, const char *name)
  {
  	unsigned i;
  	const char *const *name_ptr = driv->board_name;
  	for (i = 0; i < driv->num_names; i++) {
  		if (strcmp(*name_ptr, name) == 0)
  			return (void *)name_ptr;
  		name_ptr =
  		    (const char *const *)((const char *)name_ptr +
  					  driv->offset);
  	}
  
  	return NULL;
  }
  
  void comedi_report_boards(struct comedi_driver *driv)
  {
  	unsigned int i;
  	const char *const *name_ptr;
  
  	printk("comedi: valid board names for %s driver are:\n",
  	       driv->driver_name);
  
  	name_ptr = driv->board_name;
  	for (i = 0; i < driv->num_names; i++) {
  		printk(" %s\n", *name_ptr);
  		name_ptr = (const char **)((char *)name_ptr + driv->offset);
  	}
  
  	if (driv->num_names == 0)
  		printk(" %s\n", driv->driver_name);
  }
  
  static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
  {
  	return -EINVAL;
  }
  
  int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
  	       struct comedi_insn *insn, unsigned int *data)
  {
  	return -EINVAL;
  }
  
  static int insn_rw_emulate_bits(struct comedi_device *dev,
  				struct comedi_subdevice *s,
  				struct comedi_insn *insn, unsigned int *data)
  {
  	struct comedi_insn new_insn;
  	int ret;
  	static const unsigned channels_per_bitfield = 32;
  
  	unsigned chan = CR_CHAN(insn->chanspec);
  	const unsigned base_bitfield_channel =
  	    (chan < channels_per_bitfield) ? 0 : chan;
  	unsigned int new_data[2];
  	memset(new_data, 0, sizeof(new_data));
  	memset(&new_insn, 0, sizeof(new_insn));
  	new_insn.insn = INSN_BITS;
  	new_insn.chanspec = base_bitfield_channel;
  	new_insn.n = 2;
  	new_insn.data = new_data;
  	new_insn.subdev = insn->subdev;
  
  	if (insn->insn == INSN_WRITE) {
  		if (!(s->subdev_flags & SDF_WRITABLE))
  			return -EINVAL;
  		new_data[0] = 1 << (chan - base_bitfield_channel);	/* mask */
  		new_data[1] = data[0] ? (1 << (chan - base_bitfield_channel)) : 0;	/* bits */
  	}
  
  	ret = s->insn_bits(dev, s, &new_insn, new_data);
  	if (ret < 0)
  		return ret;
  
  	if (insn->insn == INSN_READ)
  		data[0] = (new_data[1] >> (chan - base_bitfield_channel)) & 1;
  
  	return 1;
  }
  
  static inline unsigned long uvirt_to_kva(pgd_t *pgd, unsigned long adr)
  {
  	unsigned long ret = 0UL;
  	pmd_t *pmd;
  	pte_t *ptep, pte;
  	pud_t *pud;
  
  	if (!pgd_none(*pgd)) {
  		pud = pud_offset(pgd, adr);
  		pmd = pmd_offset(pud, adr);
  		if (!pmd_none(*pmd)) {
  			ptep = pte_offset_kernel(pmd, adr);
  			pte = *ptep;
  			if (pte_present(pte)) {
  				ret = (unsigned long)
  				    page_address(pte_page(pte));
  				ret |= (adr & (PAGE_SIZE - 1));
  			}
  		}
  	}
  	return ret;
  }
  
  static inline unsigned long kvirt_to_kva(unsigned long adr)
  {
  	unsigned long va, kva;
  
  	va = adr;
  	kva = uvirt_to_kva(pgd_offset_k(va), va);
  
  	return kva;
  }
  
  int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
  		     unsigned long new_size)
  {
  	struct comedi_async *async = s->async;
  
  	/* Round up new_size to multiple of PAGE_SIZE */
  	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;
  
  	/* if no change is required, do nothing */
  	if (async->prealloc_buf && async->prealloc_bufsz == new_size)
  		return 0;
  
  	/*  deallocate old buffer */
  	if (async->prealloc_buf) {
  		vunmap(async->prealloc_buf);
  		async->prealloc_buf = NULL;
  		async->prealloc_bufsz = 0;
  	}
  	if (async->buf_page_list) {
  		unsigned i;
  		for (i = 0; i < async->n_buf_pages; ++i) {
  			if (async->buf_page_list[i].virt_addr) {
  				mem_map_unreserve(virt_to_page
  						  (async->buf_page_list[i].
  						   virt_addr));
  				if (s->async_dma_dir != DMA_NONE) {
  					dma_free_coherent(dev->hw_dev,
  							  PAGE_SIZE,
  							  async->
  							  buf_page_list
  							  [i].virt_addr,
  							  async->
  							  buf_page_list
  							  [i].dma_addr);
  				} else {
  					free_page((unsigned long)
  						  async->buf_page_list[i].
  						  virt_addr);
  				}
  			}
  		}
  		vfree(async->buf_page_list);
  		async->buf_page_list = NULL;
  		async->n_buf_pages = 0;
  	}
  	/*  allocate new buffer */
  	if (new_size) {
  		unsigned i = 0;
  		unsigned n_pages = new_size >> PAGE_SHIFT;
  		struct page **pages = NULL;
  
  		async->buf_page_list =
  		    vmalloc(sizeof(struct comedi_buf_page) * n_pages);
  		if (async->buf_page_list) {
  			memset(async->buf_page_list, 0,
  			       sizeof(struct comedi_buf_page) * n_pages);
  			pages = vmalloc(sizeof(struct page *) * n_pages);
  		}
  		if (pages) {
  			for (i = 0; i < n_pages; i++) {
  				if (s->async_dma_dir != DMA_NONE) {
  					async->buf_page_list[i].virt_addr =
  					    dma_alloc_coherent(dev->hw_dev,
  							       PAGE_SIZE,
  							       &async->
  							       buf_page_list
  							       [i].dma_addr,
  							       GFP_KERNEL |
  							       __GFP_COMP);
  				} else {
  					async->buf_page_list[i].virt_addr =
  					    (void *)
  					    get_zeroed_page(GFP_KERNEL);
  				}
  				if (async->buf_page_list[i].virt_addr == NULL)
  					break;
  
  				mem_map_reserve(virt_to_page
  						(async->buf_page_list[i].
  						 virt_addr));
  				pages[i] =
  				    virt_to_page(async->
  						 buf_page_list[i].virt_addr);
  			}
  		}
  		if (i == n_pages) {
  			async->prealloc_buf =
  			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NOCACHE);
  		}
  		vfree(pages);
  
  		if (async->prealloc_buf == NULL) {
  			/* Some allocation failed above. */
  			if (async->buf_page_list) {
  				for (i = 0; i < n_pages; i++) {
  					if (async->buf_page_list[i].virt_addr ==
  					    NULL) {
  						break;
  					}
  					mem_map_unreserve(virt_to_page
  							  (async->buf_page_list
  							   [i].virt_addr));
  					if (s->async_dma_dir != DMA_NONE) {
  						dma_free_coherent(dev->hw_dev,
  								  PAGE_SIZE,
  								  async->
  								  buf_page_list
  								  [i].virt_addr,
  								  async->
  								  buf_page_list
  								  [i].dma_addr);
  					} else {
  						free_page((unsigned long)
  							  async->buf_page_list
  							  [i].virt_addr);
  					}
  				}
  				vfree(async->buf_page_list);
  				async->buf_page_list = NULL;
  			}
  			return -ENOMEM;
  		}
  		async->n_buf_pages = n_pages;
  	}
  	async->prealloc_bufsz = new_size;
  
  	return 0;
  }
  
  /* munging is applied to data by core as it passes between user
   * and kernel space */
  unsigned int comedi_buf_munge(struct comedi_async *async,
  			      unsigned int num_bytes)
  {
  	struct comedi_subdevice *s = async->subdevice;
  	unsigned int count = 0;
  	const unsigned num_sample_bytes = bytes_per_sample(s);
  
  	if (s->munge == NULL || (async->cmd.flags & CMDF_RAWDATA)) {
  		async->munge_count += num_bytes;
  		BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);
  		return num_bytes;
  	}
  	/* don't munge partial samples */
  	num_bytes -= num_bytes % num_sample_bytes;
  	while (count < num_bytes) {
  		int block_size;
  
  		block_size = num_bytes - count;
  		if (block_size < 0) {
  			printk("%s: %s: bug! block_size is negative\n",
  			       __FILE__, __func__);
  			break;
  		}
  		if ((int)(async->munge_ptr + block_size -
  			  async->prealloc_bufsz) > 0)
  			block_size = async->prealloc_bufsz - async->munge_ptr;
  
  		s->munge(s->device, s, async->prealloc_buf + async->munge_ptr,
  			 block_size, async->munge_chan);
  
  		smp_wmb();	/* barrier insures data is munged in buffer before munge_count is incremented */
  
  		async->munge_chan += block_size / num_sample_bytes;
  		async->munge_chan %= async->cmd.chanlist_len;
  		async->munge_count += block_size;
  		async->munge_ptr += block_size;
  		async->munge_ptr %= async->prealloc_bufsz;
  		count += block_size;
  	}
  	BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);
  	return count;
  }
  
  unsigned int comedi_buf_write_n_available(struct comedi_async *async)
  {
  	unsigned int free_end;
  	unsigned int nbytes;
  
  	if (async == NULL)
  		return 0;
  
  	free_end = async->buf_read_count + async->prealloc_bufsz;
  	nbytes = free_end - async->buf_write_alloc_count;
  	nbytes -= nbytes % bytes_per_sample(async->subdevice);
  	/* barrier insures the read of buf_read_count in this
  	   query occurs before any following writes to the buffer which
  	   might be based on the return value from this query.
  	 */
  	smp_mb();
  	return nbytes;
  }
  
  /* allocates chunk for the writer from free buffer space */
  unsigned int comedi_buf_write_alloc(struct comedi_async *async,
  				    unsigned int nbytes)
  {
  	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
  
  	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
  		nbytes = free_end - async->buf_write_alloc_count;
  
  	async->buf_write_alloc_count += nbytes;
  	/* barrier insures the read of buf_read_count above occurs before
  	   we write data to the write-alloc'ed buffer space */
  	smp_mb();
  	return nbytes;
  }
  
  /* allocates nothing unless it can completely fulfill the request */
  unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async,
  					   unsigned int nbytes)
  {
  	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
  
  	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
  		nbytes = 0;
  
  	async->buf_write_alloc_count += nbytes;
  	/* barrier insures the read of buf_read_count above occurs before
  	   we write data to the write-alloc'ed buffer space */
  	smp_mb();
  	return nbytes;
  }
  
  /* transfers a chunk from writer to filled buffer space */
  unsigned comedi_buf_write_free(struct comedi_async *async, unsigned int nbytes)
  {
  	if ((int)(async->buf_write_count + nbytes -
  		  async->buf_write_alloc_count) > 0) {
  		printk
  		    ("comedi: attempted to write-free more bytes than have been write-allocated.\n");
  		nbytes = async->buf_write_alloc_count - async->buf_write_count;
  	}
  	async->buf_write_count += nbytes;
  	async->buf_write_ptr += nbytes;
  	comedi_buf_munge(async, async->buf_write_count - async->munge_count);
  	if (async->buf_write_ptr >= async->prealloc_bufsz)
  		async->buf_write_ptr %= async->prealloc_bufsz;
  
  	return nbytes;
  }
  
  /* allocates a chunk for the reader from filled (and munged) buffer space */
  unsigned comedi_buf_read_alloc(struct comedi_async *async, unsigned nbytes)
  {
  	if ((int)(async->buf_read_alloc_count + nbytes - async->munge_count) >
  	    0) {
  		nbytes = async->munge_count - async->buf_read_alloc_count;
  	}
  	async->buf_read_alloc_count += nbytes;
  	/* barrier insures read of munge_count occurs before we actually read
  	   data out of buffer */
  	smp_rmb();
  	return nbytes;
  }
  
  /* transfers control of a chunk from reader to free buffer space */
  unsigned comedi_buf_read_free(struct comedi_async *async, unsigned int nbytes)
  {
  	/*  barrier insures data has been read out of buffer before read count is incremented */
  	smp_mb();
  	if ((int)(async->buf_read_count + nbytes -
  		  async->buf_read_alloc_count) > 0) {
  		printk
  		    ("comedi: attempted to read-free more bytes than have been read-allocated.\n");
  		nbytes = async->buf_read_alloc_count - async->buf_read_count;
  	}
  	async->buf_read_count += nbytes;
  	async->buf_read_ptr += nbytes;
  	async->buf_read_ptr %= async->prealloc_bufsz;
  	return nbytes;
  }
  
  void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
  			  const void *data, unsigned int num_bytes)
  {
  	unsigned int write_ptr = async->buf_write_ptr + offset;
  
  	if (write_ptr >= async->prealloc_bufsz)
  		write_ptr %= async->prealloc_bufsz;
  
  	while (num_bytes) {
  		unsigned int block_size;
  
  		if (write_ptr + num_bytes > async->prealloc_bufsz)
  			block_size = async->prealloc_bufsz - write_ptr;
  		else
  			block_size = num_bytes;
  
  		memcpy(async->prealloc_buf + write_ptr, data, block_size);
  
  		data += block_size;
  		num_bytes -= block_size;
  
  		write_ptr = 0;
  	}
  }
  
  void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
  			    void *dest, unsigned int nbytes)
  {
  	void *src;
  	unsigned int read_ptr = async->buf_read_ptr + offset;
  
  	if (read_ptr >= async->prealloc_bufsz)
  		read_ptr %= async->prealloc_bufsz;
  
  	while (nbytes) {
  		unsigned int block_size;
  
  		src = async->prealloc_buf + read_ptr;
  
  		if (nbytes >= async->prealloc_bufsz - read_ptr)
  			block_size = async->prealloc_bufsz - read_ptr;
  		else
  			block_size = nbytes;
  
  		memcpy(dest, src, block_size);
  		nbytes -= block_size;
  		dest += block_size;
  		read_ptr = 0;
  	}
  }
  
  unsigned int comedi_buf_read_n_available(struct comedi_async *async)
  {
  	unsigned num_bytes;
  
  	if (async == NULL)
  		return 0;
  	num_bytes = async->munge_count - async->buf_read_count;
  	/* barrier insures the read of munge_count in this
  	   query occurs before any following reads of the buffer which
  	   might be based on the return value from this query.
  	 */
  	smp_rmb();
  	return num_bytes;
  }
  
  int comedi_buf_get(struct comedi_async *async, short *x)
  {
  	unsigned int n = comedi_buf_read_n_available(async);
  
  	if (n < sizeof(short))
  		return 0;
  	comedi_buf_read_alloc(async, sizeof(short));
  	*x = *(short *)(async->prealloc_buf + async->buf_read_ptr);
  	comedi_buf_read_free(async, sizeof(short));
  	return 1;
  }
  
  int comedi_buf_put(struct comedi_async *async, short x)
  {
  	unsigned int n = comedi_buf_write_alloc_strict(async, sizeof(short));
  
  	if (n < sizeof(short)) {
  		async->events |= COMEDI_CB_ERROR;
  		return 0;
  	}
  	*(short *)(async->prealloc_buf + async->buf_write_ptr) = x;
  	comedi_buf_write_free(async, sizeof(short));
  	return 1;
  }
  
  void comedi_reset_async_buf(struct comedi_async *async)
  {
  	async->buf_write_alloc_count = 0;
  	async->buf_write_count = 0;
  	async->buf_read_alloc_count = 0;
  	async->buf_read_count = 0;
  
  	async->buf_write_ptr = 0;
  	async->buf_read_ptr = 0;
  
  	async->cur_chan = 0;
  	async->scan_progress = 0;
  	async->munge_chan = 0;
  	async->munge_count = 0;
  	async->munge_ptr = 0;
  
  	async->events = 0;
  }
  
  int comedi_auto_config(struct device *hardware_device, const char *board_name,
  		       const int *options, unsigned num_options)
  {
  	struct comedi_devconfig it;
  	int minor;
  	struct comedi_device_file_info *dev_file_info;
  	int retval;
  	unsigned *private_data = NULL;
  
  	if (!comedi_autoconfig) {
  		dev_set_drvdata(hardware_device, NULL);
  		return 0;
  	}
  
  	minor = comedi_alloc_board_minor(hardware_device);
  	if (minor < 0)
  		return minor;
  
  	private_data = kmalloc(sizeof(unsigned), GFP_KERNEL);
  	if (private_data == NULL) {
  		retval = -ENOMEM;
  		goto cleanup;
  	}
  	*private_data = minor;
  	dev_set_drvdata(hardware_device, private_data);
  
  	dev_file_info = comedi_get_device_file_info(minor);
  
  	memset(&it, 0, sizeof(it));
  	strncpy(it.board_name, board_name, COMEDI_NAMELEN);
  	it.board_name[COMEDI_NAMELEN - 1] = '\0';
  	BUG_ON(num_options > COMEDI_NDEVCONFOPTS);
  	memcpy(it.options, options, num_options * sizeof(int));
  
  	mutex_lock(&dev_file_info->device->mutex);
  	retval = comedi_device_attach(dev_file_info->device, &it);
  	mutex_unlock(&dev_file_info->device->mutex);
  
  cleanup:
  	if (retval < 0) {
  		kfree(private_data);
  		comedi_free_board_minor(minor);
  	}
  	return retval;
  }
  
  void comedi_auto_unconfig(struct device *hardware_device)
  {
  	unsigned *minor = (unsigned *)dev_get_drvdata(hardware_device);
  	if (minor == NULL)
  		return;
  
  	BUG_ON(*minor >= COMEDI_NUM_BOARD_MINORS);
  
  	comedi_free_board_minor(*minor);
  	dev_set_drvdata(hardware_device, NULL);
  	kfree(minor);
  }
  
  int comedi_pci_auto_config(struct pci_dev *pcidev, const char *board_name)
  {
  	int options[2];
  
  	/*  pci bus */
  	options[0] = pcidev->bus->number;
  	/*  pci slot */
  	options[1] = PCI_SLOT(pcidev->devfn);
  
  	return comedi_auto_config(&pcidev->dev, board_name,
  				  options, ARRAY_SIZE(options));
  }
  
  void comedi_pci_auto_unconfig(struct pci_dev *pcidev)
  {
  	comedi_auto_unconfig(&pcidev->dev);
  }
  
  int comedi_usb_auto_config(struct usb_device *usbdev, const char *board_name)
  {
  	BUG_ON(usbdev == NULL);
  	return comedi_auto_config(&usbdev->dev, board_name, NULL, 0);
  }
  
  void comedi_usb_auto_unconfig(struct usb_device *usbdev)
  {
  	BUG_ON(usbdev == NULL);
  	comedi_auto_unconfig(&usbdev->dev);
  }
  