path: root/drivers/comedi/drivers.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  module/drivers.c
 *  functions for manipulating drivers
 *
 *  COMEDI - Linux Control and Measurement Device Interface
 *  Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
 *  Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net>
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/dma-direction.h>
#include <linux/interrupt.h>
#include <linux/firmware.h>
#include <linux/comedi/comedidev.h>
#include "comedi_internal.h"

struct comedi_driver *comedi_drivers;
/* protects access to comedi_drivers */
DEFINE_MUTEX(comedi_drivers_list_lock);

/**
 * comedi_set_hw_dev() - Set hardware device associated with COMEDI device
 * @dev: COMEDI device.
 * @hw_dev: Hardware device.
 *
 * For automatically configured COMEDI devices (resulting from a call to
 * comedi_auto_config() or one of its wrappers from the low-level COMEDI
 * driver), comedi_set_hw_dev() is called automatically by the COMEDI core
 * to associate the COMEDI device with the hardware device.  It can also be
 * called directly by "legacy" low-level COMEDI drivers that rely on the
 * %COMEDI_DEVCONFIG ioctl to configure the hardware as long as the hardware
 * has a &struct device.
 *
 * If @dev->hw_dev is NULL, it gets a reference to @hw_dev and sets
 * @dev->hw_dev, otherwise, it does nothing.  Calling it multiple times
 * with the same hardware device is not considered an error.  If it gets
 * a reference to the hardware device, it will be automatically 'put' when
 * the device is detached from COMEDI.
 *
 * Returns 0 if @dev->hw_dev was NULL or the same as @hw_dev, otherwise
 * returns -EEXIST.
 */
int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
{
	if (hw_dev == dev->hw_dev)
		return 0;
	if (dev->hw_dev)
		return -EEXIST;
	dev->hw_dev = get_device(hw_dev);
	return 0;
}
EXPORT_SYMBOL_GPL(comedi_set_hw_dev);

static void comedi_clear_hw_dev(struct comedi_device *dev)
{
	put_device(dev->hw_dev);
	dev->hw_dev = NULL;
}

/**
 * comedi_alloc_devpriv() - Allocate memory for the device private data
 * @dev: COMEDI device.
 * @size: Size of the memory to allocate.
 *
 * The allocated memory is zero-filled.  @dev->private points to it on
 * return.  The memory will be automatically freed when the COMEDI device is
 * "detached".
 *
 * Returns a pointer to the allocated memory, or NULL on failure.
 */
void *comedi_alloc_devpriv(struct comedi_device *dev, size_t size)
{
	dev->private = kzalloc(size, GFP_KERNEL);
	return dev->private;
}
EXPORT_SYMBOL_GPL(comedi_alloc_devpriv);

/**
 * comedi_alloc_subdevices() - Allocate subdevices for COMEDI device
 * @dev: COMEDI device.
 * @num_subdevices: Number of subdevices to allocate.
 *
 * Allocates and initializes an array of &struct comedi_subdevice for the
 * COMEDI device.  If successful, sets @dev->subdevices to point to the
 * first one and @dev->n_subdevices to the number.
 *
 * Returns 0 on success, -EINVAL if @num_subdevices is < 1, or -ENOMEM if
 * failed to allocate the memory.
 */
int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
{
	struct comedi_subdevice *s;
	int i;

	if (num_subdevices < 1)
		return -EINVAL;

	s = kcalloc(num_subdevices, sizeof(*s), GFP_KERNEL);
	if (!s)
		return -ENOMEM;
	dev->subdevices = s;
	dev->n_subdevices = num_subdevices;

	for (i = 0; i < num_subdevices; ++i) {
		s = &dev->subdevices[i];
		s->device = dev;
		s->index = i;
		s->async_dma_dir = DMA_NONE;
		spin_lock_init(&s->spin_lock);
		s->minor = -1;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(comedi_alloc_subdevices);

/**
 * comedi_alloc_subdev_readback() - Allocate memory for the subdevice readback
 * @s: COMEDI subdevice.
 *
 * This is called by low-level COMEDI drivers to allocate an array to record
 * the last values written to a subdevice's analog output channels (at least
 * by the %INSN_WRITE instruction), to allow them to be read back by an
 * %INSN_READ instruction.  It also provides a default handler for the
 * %INSN_READ instruction unless one has already been set.
 *
 * On success, @s->readback points to the first element of the array, which
 * is zero-filled.  The low-level driver is responsible for updating its
 * contents.  @s->insn_read will be set to comedi_readback_insn_read()
 * unless it is already non-NULL.
 *
 * Returns 0 on success, -EINVAL if the subdevice has no channels, or
 * -ENOMEM on allocation failure.
 */
int comedi_alloc_subdev_readback(struct comedi_subdevice *s)
{
	if (!s->n_chan)
		return -EINVAL;

	s->readback = kcalloc(s->n_chan, sizeof(*s->readback), GFP_KERNEL);
	if (!s->readback)
		return -ENOMEM;

	if (!s->insn_read)
		s->insn_read = comedi_readback_insn_read;

	return 0;
}
EXPORT_SYMBOL_GPL(comedi_alloc_subdev_readback);

static void comedi_device_detach_cleanup(struct comedi_device *dev)
{
	int i;
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->attach_lock);
	lockdep_assert_held(&dev->mutex);
	if (dev->subdevices