Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1183 insertions, 0 deletions

diff --git a/drivers/comedi/drivers.c b/drivers/comedi/drivers.c
new file mode 100644
index 000000000..d4e2ed709
--- /dev/null
+++ b/drivers/comedi/drivers.c
@@ -0,0 +1,1183 @@
+// 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) {
+		for (i = 0; i < dev->n_subdevices; i++) {
+			s = &dev->subdevices[i];
+			if (comedi_can_auto_free_spriv(s))
+				kfree(s->private);
+			comedi_free_subdevice_minor(s);
+			if (s->async) {
+				comedi_buf_alloc(dev, s, 0);
+				kfree(s->async);
+			}
+			kfree(s->readback);
+		}
+		kfree(dev->subdevices);
+		dev->subdevices = NULL;
+		dev->n_subdevices = 0;
+	}
+	kfree(dev->private);
+	kfree(dev->pacer);
+	dev->private = NULL;
+	dev->pacer = NULL;
+	dev->driver = NULL;
+	dev->board_name = NULL;
+	dev->board_ptr = NULL;
+	dev->mmio = NULL;
+	dev->iobase = 0;
+	dev->iolen = 0;
+	dev->ioenabled = false;
+	dev->irq = 0;
+	dev->read_subdev = NULL;
+	dev->write_subdev = NULL;
+	dev->open = NULL;
+	dev->close = NULL;
+	comedi_clear_hw_dev(dev);
+}
+
+void comedi_device_detach(struct comedi_device *dev)
+{
+	lockdep_assert_held(&dev->mutex);
+	comedi_device_cancel_all(dev);
+	down_write(&dev->attach_lock);
+	dev->attached = false;
+	dev->detach_count++;
+	if (dev->driver)
+		dev->driver->detach(dev);
+	comedi_device_detach_cleanup(dev);
+	up_write(&dev->attach_lock);
+}
+
+static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
+{
+	return -EINVAL;
+}
+
+static int insn_device_inval(struct comedi_device *dev,
+			     struct comedi_insn *insn, unsigned int *data)
+{
+	return -EINVAL;
+}
+
+static unsigned int get_zero_valid_routes(struct comedi_device *dev,
+					  unsigned int n_pairs,
+					  unsigned int *pair_data)
+{
+	return 0;
+}
+
+int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
+	       struct comedi_insn *insn, unsigned int *data)
+{
+	return -EINVAL;
+}
+
+/**
+ * comedi_readback_insn_read() - A generic (*insn_read) for subdevice readback.
+ * @dev: COMEDI device.
+ * @s: COMEDI subdevice.
+ * @insn: COMEDI instruction.
+ * @data: Pointer to return the readback data.
+ *
+ * Handles the %INSN_READ instruction for subdevices that use the readback
+ * array allocated by comedi_alloc_subdev_readback().  It may be used
+ * directly as the subdevice's handler (@s->insn_read) or called via a
+ * wrapper.
+ *
+ * @insn->n is normally 1, which will read a single value.  If higher, the
+ * same element of the readback array will be read multiple times.
+ *
+ * Returns @insn->n on success, or -EINVAL if @s->readback is NULL.
+ */
+int comedi_readback_insn_read(struct comedi_device *dev,
+			      struct comedi_subdevice *s,
+			      struct comedi_insn *insn,
+			      unsigned int *data)
+{
+	unsigned int chan = CR_CHAN(insn->chanspec);
+	int i;
+
+	if (!s->readback)
+		return -EINVAL;
+
+	for (i = 0; i < insn->n; i++)
+		data[i] = s->readback[chan];
+
+	return insn->n;
+}
+EXPORT_SYMBOL_GPL(comedi_readback_insn_read);
+
+/**
+ * comedi_timeout() - Busy-wait for a driver condition to occur
+ * @dev: COMEDI device.
+ * @s: COMEDI subdevice.
+ * @insn: COMEDI instruction.
+ * @cb: Callback to check for the condition.
+ * @context: Private context from the driver.
+ *
+ * Busy-waits for up to a second (%COMEDI_TIMEOUT_MS) for the condition or
+ * some error (other than -EBUSY) to occur.  The parameters @dev, @s, @insn,
+ * and @context are passed to the callback function, which returns -EBUSY to
+ * continue waiting or some other value to stop waiting (generally 0 if the
+ * condition occurred, or some error value).
+ *
+ * Returns -ETIMEDOUT if timed out, otherwise the return value from the
+ * callback function.
+ */
+int comedi_timeout(struct comedi_device *dev,
+		   struct comedi_subdevice *s,
+		   struct comedi_insn *insn,
+		   int (*cb)(struct comedi_device *dev,
+			     struct comedi_subdevice *s,
+			     struct comedi_insn *insn,
+			     unsigned long context),
+		   unsigned long context)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(COMEDI_TIMEOUT_MS);
+	int ret;
+
+	while (time_before(jiffies, timeout)) {
+		ret = cb(dev, s, insn, context);
+		if (ret != -EBUSY)
+			return ret;	/* success (0) or non EBUSY errno */
+		cpu_relax();
+	}
+	return -ETIMEDOUT;
+}
+EXPORT_SYMBOL_GPL(comedi_timeout);
+
+/**
+ * comedi_dio_insn_config() - Boilerplate (*insn_config) for DIO subdevices
+ * @dev: COMEDI device.
+ * @s: COMEDI subdevice.
+ * @insn: COMEDI instruction.
+ * @data: Instruction parameters and return data.
+ * @mask: io_bits mask for grouped channels, or 0 for single channel.
+ *
+ * If @mask is 0, it is replaced with a single-bit mask corresponding to the
+ * channel number specified by @insn->chanspec.  Otherwise, @mask
+ * corresponds to a group of channels (which should include the specified
+ * channel) that are always configured together as inputs or outputs.
+ *
+ * Partially handles the %INSN_CONFIG_DIO_INPUT, %INSN_CONFIG_DIO_OUTPUTS,
+ * and %INSN_CONFIG_DIO_QUERY instructions.  The first two update
+ * @s->io_bits to record the directions of the masked channels.  The last
+ * one sets @data[1] to the current direction of the group of channels
+ * (%COMEDI_INPUT) or %COMEDI_OUTPUT) as recorded in @s->io_bits.
+ *
+ * The caller is responsible for updating the DIO direction in the hardware
+ * registers if this function returns 0.
+ *
+ * Returns 0 for a %INSN_CONFIG_DIO_INPUT or %INSN_CONFIG_DIO_OUTPUT
+ * instruction, @insn->n (> 0) for a %INSN_CONFIG_DIO_QUERY instruction, or
+ * -EINVAL for some other instruction.
+ */
+int comedi_dio_insn_config(struct comedi_device *dev,
+			   struct comedi_subdevice *s,
+			   struct comedi_insn *insn,
+			   unsigned int *data,
+			   unsigned int mask)
+{
+	unsigned int chan_mask = 1 << CR_CHAN(insn->chanspec);
+
+	if (!mask)
+		mask = chan_mask;
+
+	switch (data[0]) {
+	case INSN_CONFIG_DIO_INPUT:
+		s->io_bits &= ~mask;
+		break;
+
+	case INSN_CONFIG_DIO_OUTPUT:
+		s->io_bits |= mask;
+		break;
+
+	case INSN_CONFIG_DIO_QUERY:
+		data[1] = (s->io_bits & mask) ? COMEDI_OUTPUT : COMEDI_INPUT;
+		return insn->n;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(comedi_dio_insn_config);
+
+/**
+ * comedi_dio_update_state() - Update the internal state of DIO subdevices
+ * @s: COMEDI subdevice.
+ * @data: The channel mask and bits to update.
+ *
+ * Updates @s->state which holds the internal state of the outputs for DIO
+ * or DO subdevices (up to 32 channels).  @data[0] contains a bit-mask of
+ * the channels to be updated.  @data[1] contains a bit-mask of those
+ * channels to be set to '1'.  The caller is responsible for updating the
+ * outputs in hardware according to @s->state.  As a minimum, the channels
+ * in the returned bit-mask need to be updated.
+ *
+ * Returns @mask with non-existent channels removed.
+ */
+unsigned int comedi_dio_update_state(struct comedi_subdevice *s,
+				     unsigned int *data)
+{
+	unsigned int chanmask = (s->n_chan < 32) ? ((1 << s->n_chan) - 1)
+						 : 0xffffffff;
+	unsigned int mask = data[0] & chanmask;
+	unsigned int bits = data[1];
+
+	if (mask) {
+		s->state &= ~mask;
+		s->state |= (bits & mask);
+	}
+
+	return mask;
+}
+EXPORT_SYMBOL_GPL(comedi_dio_update_state);
+
+/**
+ * comedi_bytes_per_scan_cmd() - Get length of asynchronous command "scan" in
+ * bytes
+ * @s: COMEDI subdevice.
+ * @cmd: COMEDI command.
+ *
+ * Determines the overall scan length according to the subdevice type and the
+ * number of channels in the scan for the specified command.
+ *
+ * For digital input, output or input/output subdevices, samples for
+ * multiple channels are assumed to be packed into one or more unsigned
+ * short or unsigned int values according to the subdevice's %SDF_LSAMPL
+ * flag.  For other types of subdevice, samples are assumed to occupy a
+ * whole unsigned short or unsigned int according to the %SDF_LSAMPL flag.
+ *
+ * Returns the overall scan length in bytes.
+ */
+unsigned int comedi_bytes_per_scan_cmd(struct comedi_subdevice *s,
+				       struct comedi_cmd *cmd)
+{
+	unsigned int num_samples;
+	unsigned int bits_per_sample;
+
+	switch (s->type) {
+	case COMEDI_SUBD_DI:
+	case COMEDI_SUBD_DO:
+	case COMEDI_SUBD_DIO:
+		bits_per_sample = 8 * comedi_bytes_per_sample(s);
+		num_samples = DIV_ROUND_UP(cmd->scan_end_arg, bits_per_sample);
+		break;
+	default:
+		num_samples = cmd->scan_end_arg;
+		break;
+	}
+	return comedi_samples_to_bytes(s, num_samples);
+}
+EXPORT_SYMBOL_GPL(comedi_bytes_per_scan_cmd);
+
+/**
+ * comedi_bytes_per_scan() - Get length of asynchronous command "scan" in bytes
+ * @s: COMEDI subdevice.
+ *
+ * Determines the overall scan length according to the subdevice type and the
+ * number of channels in the scan for the current command.
+ *
+ * For digital input, output or input/output subdevices, samples for
+ * multiple channels are assumed to be packed into one or more unsigned
+ * short or unsigned int values according to the subdevice's %SDF_LSAMPL
+ * flag.  For other types of subdevice, samples are assumed to occupy a
+ * whole unsigned short or unsigned int according to the %SDF_LSAMPL flag.
+ *
+ * Returns the overall scan length in bytes.
+ */
+unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s)
+{
+	struct comedi_cmd *cmd = &s->async->cmd;
+
+	return comedi_bytes_per_scan_cmd(s, cmd);
+}
+EXPORT_SYMBOL_GPL(comedi_bytes_per_scan);
+
+static unsigned int __comedi_nscans_left(struct comedi_subdevice *s,
+					 unsigned int nscans)
+{
+	struct comedi_async *async = s->async;
+	struct comedi_cmd *cmd = &async->cmd;
+
+	if (cmd->stop_src == TRIG_COUNT) {
+		unsigned int scans_left = 0;
+
+		if (async->scans_done < cmd->stop_arg)
+			scans_left = cmd->stop_arg - async->scans_done;
+
+		if (nscans > scans_left)
+			nscans = scans_left;
+	}
+	return nscans;
+}
+
+/**
+ * comedi_nscans_left() - Return the number of scans left in the command
+ * @s: COMEDI subdevice.
+ * @nscans: The expected number of scans or 0 for all available scans.
+ *
+ * If @nscans is 0, it is set to the number of scans available in the
+ * async buffer.
+ *
+ * If the async command has a stop_src of %TRIG_COUNT, the @nscans will be
+ * checked against the number of scans remaining to complete the command.
+ *
+ * The return value will then be either the expected number of scans or the
+ * number of scans remaining to complete the command, whichever is fewer.
+ */
+unsigned int comedi_nscans_left(struct comedi_subdevice *s,
+				unsigned int nscans)
+{
+	if (nscans == 0) {
+		unsigned int nbytes = comedi_buf_read_n_available(s);
+
+		nscans = nbytes / comedi_bytes_per_scan(s);
+	}
+	return __comedi_nscans_left(s, nscans);
+}
+EXPORT_SYMBOL_GPL(comedi_nscans_left);
+
+/**
+ * comedi_nsamples_left() - Return the number of samples left in the command
+ * @s: COMEDI subdevice.
+ * @nsamples: The expected number of samples.
+ *
+ * Returns the number of samples remaining to complete the command, or the
+ * specified expected number of samples (@nsamples), whichever is fewer.
+ */
+unsigned int comedi_nsamples_left(struct comedi_subdevice *s,
+				  unsigned int nsamples)
+{
+	struct comedi_async *async = s->async;
+	struct comedi_cmd *cmd = &async->cmd;
+	unsigned long long scans_left;
+	unsigned long long samples_left;
+
+	if (cmd->stop_src != TRIG_COUNT)
+		return nsamples;
+
+	scans_left = __comedi_nscans_left(s, cmd->stop_arg);
+	if (!scans_left)
+		return 0;
+
+	samples_left = scans_left * cmd->scan_end_arg -
+		comedi_bytes_to_samples(s, async->scan_progress);
+
+	if (samples_left < nsamples)
+		return samples_left;
+	return nsamples;
+}
+EXPORT_SYMBOL_GPL(comedi_nsamples_left);
+
+/**
+ * comedi_inc_scan_progress() - Update scan progress in asynchronous command
+ * @s: COMEDI subdevice.
+ * @num_bytes: Amount of data in bytes to increment scan progress.
+ *
+ * Increments the scan progress by the number of bytes specified by @num_bytes.
+ * If the scan progress reaches or exceeds the scan length in bytes, reduce
+ * it modulo the scan length in bytes and set the "end of scan" asynchronous
+ * event flag (%COMEDI_CB_EOS) to be processed later.
+ */
+void comedi_inc_scan_progress(struct comedi_subdevice *s,
+			      unsigned int num_bytes)
+{
+	struct comedi_async *async = s->async;
+	struct comedi_cmd *cmd = &async->cmd;
+	unsigned int scan_length = comedi_bytes_per_scan(s);
+
+	/* track the 'cur_chan' for non-SDF_PACKED subdevices */
+	if (!(s->subdev_flags & SDF_PACKED)) {
+		async->cur_chan += comedi_bytes_to_samples(s, num_bytes);
+		async->cur_chan %= cmd->chanlist_len;
+	}
+
+	async->scan_progress += num_bytes;
+	if (async->scan_progress >= scan_length) {
+		unsigned int nscans = async->scan_progress / scan_length;
+
+		if (async->scans_done < (UINT_MAX - nscans))
+			async->scans_done += nscans;
+		else
+			async->scans_done = UINT_MAX;
+
+		async->scan_progress %= scan_length;
+		async->events |= COMEDI_CB_EOS;
+	}
+}
+EXPORT_SYMBOL_GPL(comedi_inc_scan_progress);
+
+/**
+ * comedi_handle_events() - Handle events and possibly stop acquisition
+ * @dev: COMEDI device.
+ * @s: COMEDI subdevice.
+ *
+ * Handles outstanding asynchronous acquisition event flags associated
+ * with the subdevice.  Call the subdevice's @s->cancel() handler if the
+ * "end of acquisition", "error" or "overflow" event flags are set in order
+ * to stop the acquisition at the driver level.
+ *
+ * Calls comedi_event() to further process the event flags, which may mark
+ * the asynchronous command as no longer running, possibly terminated with
+ * an error, and may wake up tasks.
+ *
+ * Return a bit-mask of the handled events.
+ */
+unsigned int comedi_handle_events(struct comedi_device *dev,
+				  struct comedi_subdevice *s)
+{
+	unsigned int events = s->async->events;
+
+	if (events == 0)
+		return events;
+
+	if ((events & COMEDI_CB_CANCEL_MASK) && s->cancel)
+		s->cancel(dev, s);
+
+	comedi_event(dev, s);
+
+	return events;
+}
+EXPORT_SYMBOL_GPL(comedi_handle_events);
+
+static int insn_rw_emulate_bits(struct comedi_device *dev,
+				struct comedi_subdevice *s,
+				struct comedi_insn *insn,
+				unsigned int *data)
+{
+	struct comedi_insn _insn;
+	unsigned int chan = CR_CHAN(insn->chanspec);
+	unsigned int base_chan = (chan < 32) ? 0 : chan;
+	unsigned int _data[2];
+	int ret;
+
+	memset(_data, 0, sizeof(_data));
+	memset(&_insn, 0, sizeof(_insn));
+	_insn.insn = INSN_BITS;
+	_insn.chanspec = base_chan;
+	_insn.n = 2;
+	_insn.subdev = insn->subdev;
+
+	if (insn->insn == INSN_WRITE) {
+		if (!(s->subdev_flags & SDF_WRITABLE))
+			return -EINVAL;
+		_data[0] = 1 << (chan - base_chan);		    /* mask */
+		_data[1] = data[0] ? (1 << (chan - base_chan)) : 0; /* bits */
+	}
+
+	ret = s->insn_bits(dev, s, &_insn, _data);
+	if (ret < 0)
+		return ret;
+
+	if (insn->insn == INSN_READ)
+		data[0] = (_data[1] >> (chan - base_chan)) & 1;
+
+	return 1;
+}
+
+static int __comedi_device_postconfig_async(struct comedi_device *dev,
+					    struct comedi_subdevice *s)
+{
+	struct comedi_async *async;
+	unsigned int buf_size;
+	int ret;
+
+	lockdep_assert_held(&dev->mutex);
+	if ((s->subdev_flags & (SDF_CMD_READ | SDF_CMD_WRITE)) == 0) {
+		dev_warn(dev->class_dev,
+			 "async subdevices must support SDF_CMD_READ or SDF_CMD_WRITE\n");
+		return -EINVAL;
+	}
+	if (!s->do_cmdtest) {
+		dev_warn(dev->class_dev,
+			 "async subdevices must have a do_cmdtest() function\n");
+		return -EINVAL;
+	}
+	if (!s->cancel)
+		dev_warn(dev->class_dev,
+			 "async subdevices should have a cancel() function\n");
+
+	async = kzalloc(sizeof(*async), GFP_KERNEL);
+	if (!async)
+		return -ENOMEM;
+
+	init_waitqueue_head(&async->wait_head);
+	s->async = async;
+
+	async->max_bufsize = comedi_default_buf_maxsize_kb * 1024;
+	buf_size = comedi_default_buf_size_kb * 1024;
+	if (buf_size > async->max_bufsize)
+		buf_size = async->max_bufsize;
+
+	if (comedi_buf_alloc(dev, s, buf_size) < 0) {
+		dev_warn(dev->class_dev, "Buffer allocation failed\n");
+		return -ENOMEM;
+	}
+	if (s->buf_change) {
+		ret = s->buf_change(dev, s);
+		if (ret < 0)
+			return ret;
+	}
+
+	comedi_alloc_subdevice_minor(s);
+
+	return 0;
+}
+
+static int __comedi_device_postconfig(struct comedi_device *dev)
+{
+	struct comedi_subdevice *s;
+	int ret;
+	int i;
+
+	lockdep_assert_held(&dev->mutex);
+	if (!dev->insn_device_config)
+		dev->insn_device_config = insn_device_inval;
+
+	if (!dev->get_valid_routes)
+		dev->get_valid_routes = get_zero_valid_routes;
+
+	for (i = 0; i < dev->n_subdevices; i++) {
+		s = &dev->subdevices[i];
+
+		if (s->type == COMEDI_SUBD_UNUSED)
+			continue;
+
+		if (s->type == COMEDI_SUBD_DO) {
+			if (s->n_chan < 32)
+				s->io_bits = (1 << s->n_chan) - 1;
+			else
+				s->io_bits = 0xffffffff;
+		}
+
+		if (s->len_chanlist == 0)
+			s->len_chanlist = 1;
+
+		if (s->do_cmd) {
+			ret = __comedi_device_postconfig_async(dev, s);
+			if (ret)
+				return ret;
+		}
+
+		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;
+}
+
+/* do a little post-config cleanup */
+static int comedi_device_postconfig(struct comedi_device *dev)
+{
+	int ret;
+
+	lockdep_assert_held(&dev->mutex);
+	ret = __comedi_device_postconfig(dev);
+	if (ret < 0)
+		return ret;
+	down_write(&dev->attach_lock);
+	dev->attached = true;
+	up_write(&dev->attach_lock);
+	return 0;
+}
+
+/*
+ * Generic recognize function for drivers that register their supported
+ * board names.
+ *
+ * 'driv->board_name' points to a 'const char *' member within the
+ * zeroth element of an array of some private board information
+ * structure, say 'struct foo_board' containing a member 'const char
+ * *board_name' that is initialized to point to a board name string that
+ * is one of the candidates matched against this function's 'name'
+ * parameter.
+ *
+ * 'driv->offset' is the size of the private board information
+ * structure, say 'sizeof(struct foo_board)', and 'driv->num_names' is
+ * the length of the array of private board information structures.
+ *
+ * If one of the board names in the array of private board information
+ * structures matches the name supplied to this function, the function
+ * returns a pointer to the pointer to the board name, otherwise it
+ * returns NULL.  The return value ends up in the 'board_ptr' member of
+ * a 'struct comedi_device' that the low-level comedi driver's
+ * 'attach()' hook can convert to a point to a particular element of its
+ * array of private board information structures by subtracting the
+ * offset of the member that points to the board name.  (No subtraction
+ * is required if the board name pointer is the first member of the
+ * private board information structure, which is generally the case.)
+ */
+static void *comedi_recognize(struct comedi_driver *driv, const char *name)
+{
+	char **name_ptr = (char **)driv->board_name;
+	int i;
+
+	for (i = 0; i < driv->num_names; i++) {
+		if (strcmp(*name_ptr, name) == 0)
+			return name_ptr;
+		name_ptr = (void *)name_ptr + driv->offset;
+	}
+
+	return NULL;
+}
+
+static void comedi_report_boards(struct comedi_driver *driv)
+{
+	unsigned int i;
+	const char *const *name_ptr;
+
+	pr_info("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++) {
+		pr_info(" %s\n", *name_ptr);
+		name_ptr = (const char **)((char *)name_ptr + driv->offset);
+	}
+
+	if (driv->num_names == 0)
+		pr_info(" %s\n", driv->driver_name);
+}
+
+/**
+ * comedi_load_firmware() - Request and load firmware for a device
+ * @dev: COMEDI device.
+ * @device: Hardware device.
+ * @name: The name of the firmware image.
+ * @cb: Callback to the upload the firmware image.
+ * @context: Private context from the driver.
+ *
+ * Sends a firmware request for the hardware device and waits for it.  Calls
+ * the callback function to upload the firmware to the device, them releases
+ * the firmware.
+ *
+ * Returns 0 on success, -EINVAL if @cb is NULL, or a negative error number
+ * from the firmware request or the callback function.
+ */
+int comedi_load_firmware(struct comedi_device *dev,
+			 struct device *device,
+			 const char *name,
+			 int (*cb)(struct comedi_device *dev,
+				   const u8 *data, size_t size,
+				   unsigned long context),
+			 unsigned long context)
+{
+	const struct firmware *fw;
+	int ret;
+
+	if (!cb)
+		return -EINVAL;
+
+	ret = request_firmware(&fw, name, device);
+	if (ret == 0) {
+		ret = cb(dev, fw->data, fw->size, context);
+		release_firmware(fw);
+	}
+
+	return min(ret, 0);
+}
+EXPORT_SYMBOL_GPL(comedi_load_firmware);
+
+/**
+ * __comedi_request_region() - Request an I/O region for a legacy driver
+ * @dev: COMEDI device.
+ * @start: Base address of the I/O region.
+ * @len: Length of the I/O region.
+ *
+ * Requests the specified I/O port region which must start at a non-zero
+ * address.
+ *
+ * Returns 0 on success, -EINVAL if @start is 0, or -EIO if the request
+ * fails.
+ */
+int __comedi_request_region(struct comedi_device *dev,
+			    unsigned long start, unsigned long len)
+{
+	if (!start) {
+		dev_warn(dev->class_dev,
+			 "%s: a I/O base address must be specified\n",
+			 dev->board_name);
+		return -EINVAL;
+	}
+
+	if (!request_region(start, len, dev->board_name)) {
+		dev_warn(dev->class_dev, "%s: I/O port conflict (%#lx,%lu)\n",
+			 dev->board_name, start, len);
+		return -EIO;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__comedi_request_region);
+
+/**
+ * comedi_request_region() - Request an I/O region for a legacy driver
+ * @dev: COMEDI device.
+ * @start: Base address of the I/O region.
+ * @len: Length of the I/O region.
+ *
+ * Requests the specified I/O port region which must start at a non-zero
+ * address.
+ *
+ * On success, @dev->iobase is set to the base address of the region and
+ * @dev->iolen is set to its length.
+ *
+ * Returns 0 on success, -EINVAL if @start is 0, or -EIO if the request
+ * fails.
+ */
+int comedi_request_region(struct comedi_device *dev,
+			  unsigned long start, unsigned long len)
+{
+	int ret;
+
+	ret = __comedi_request_region(dev, start, len);
+	if (ret == 0) {
+		dev->iobase = start;
+		dev->iolen = len;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(comedi_request_region);
+
+/**
+ * comedi_legacy_detach() - A generic (*detach) function for legacy drivers
+ * @dev: COMEDI device.
+ *
+ * This is a simple, generic 'detach' handler for legacy COMEDI devices that
+ * just use a single I/O port region and possibly an IRQ and that don't need
+ * any special clean-up for their private device or subdevice storage.  It
+ * can also be called by a driver-specific 'detach' handler.
+ *
+ * If @dev->irq is non-zero, the IRQ will be freed.  If @dev->iobase and
+ * @dev->iolen are both non-zero, the I/O port region will be released.
+ */
+void comedi_legacy_detach(struct comedi_device *dev)
+{
+	if (dev->irq) {
+		free_irq(dev->irq, dev);
+		dev->irq = 0;
+	}
+	if (dev->iobase && dev->iolen) {
+		release_region(dev->iobase, dev->iolen);
+		dev->iobase = 0;
+		dev->iolen = 0;
+	}
+}
+EXPORT_SYMBOL_GPL(comedi_legacy_detach);
+
+int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
+{
+	struct comedi_driver *driv;
+	int ret;
+
+	lockdep_assert_held(&dev->mutex);
+	if (dev->attached)
+		return -EBUSY;
+
+	mutex_lock(&comedi_drivers_list_lock);
+	for (driv = comedi_drivers; driv; driv = driv->next) {
+		if (!try_module_get(driv->module))
+			continue;
+		if (driv->num_names) {
+			dev->board_ptr = comedi_recognize(driv, it->board_name);
+			if (dev->board_ptr)
+				break;
+		} else if (strcmp(driv->driver_name, it->board_name) == 0) {
+			break;
+		}
+		module_put(driv->module);
+	}
+	if (!driv) {
+		/*  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))
+				continue;
+			comedi_report_boards(driv);
+			module_put(driv->module);
+		}
+		ret = -EIO;
+		goto out;
+	}
+	if (!driv->attach) {
+		/* driver does not support manual configuration */
+		dev_warn(dev->class_dev,
+			 "driver '%s' does not support attach using comedi_config\n",
+			 driv->driver_name);
+		module_put(driv->module);
+		ret = -EIO;
+		goto out;
+	}
+	dev->driver = driv;
+	dev->board_name = dev->board_ptr ? *(const char **)dev->board_ptr
+					 : dev->driver->driver_name;
+	ret = driv->attach(dev, it);
+	if (ret >= 0)
+		ret = comedi_device_postconfig(dev);
+	if (ret < 0) {
+		comedi_device_detach(dev);
+		module_put(driv->module);
+	}
+	/* On success, the driver module count has been incremented. */
+out:
+	mutex_unlock(&comedi_drivers_list_lock);
+	return ret;
+}
+
+/**
+ * comedi_auto_config() - Create a COMEDI device for a hardware device
+ * @hardware_device: Hardware device.
+ * @driver: COMEDI low-level driver for the hardware device.
+ * @context: Driver context for the auto_attach handler.
+ *
+ * Allocates a new COMEDI device for the hardware device and calls the
+ * low-level driver's 'auto_attach' handler to set-up the hardware and
+ * allocate the COMEDI subdevices.  Additional "post-configuration" setting
+ * up is performed on successful return from the 'auto_attach' handler.
+ * If the 'auto_attach' handler fails, the low-level driver's 'detach'
+ * handler will be called as part of the clean-up.
+ *
+ * This is usually called from a wrapper function in a bus-specific COMEDI
+ * module, which in turn is usually called from a bus device 'probe'
+ * function in the low-level driver.
+ *
+ * Returns 0 on success, -EINVAL if the parameters are invalid or the
+ * post-configuration determines the driver has set the COMEDI device up
+ * incorrectly, -ENOMEM if failed to allocate memory, -EBUSY if run out of
+ * COMEDI minor device numbers, or some negative error number returned by
+ * the driver's 'auto_attach' handler.
+ */
+int comedi_auto_config(struct device *hardware_device,
+		       struct comedi_driver *driver, unsigned long context)
+{
+	struct comedi_device *dev;
+	int ret;
+
+	if (!hardware_device) {
+		pr_warn("BUG! %s called with NULL hardware_device\n", __func__);
+		return -EINVAL;
+	}
+	if (!driver) {
+		dev_warn(hardware_device,
+			 "BUG! %s called with NULL comedi driver\n", __func__);
+		return -EINVAL;
+	}
+
+	if (!driver->auto_attach) {
+		dev_warn(hardware_device,
+			 "BUG! comedi driver '%s' has no auto_attach handler\n",
+			 driver->driver_name);
+		return -EINVAL;
+	}
+
+	dev = comedi_alloc_board_minor(hardware_device);
+	if (IS_ERR(dev)) {
+		dev_warn(hardware_device,
+			 "driver '%s' could not create device.\n",
+			 driver->driver_name);
+		return PTR_ERR(dev);
+	}
+	/* Note: comedi_alloc_board_minor() locked dev->mutex. */
+	lockdep_assert_held(&dev->mutex);
+
+	dev->driver = driver;
+	dev->board_name = dev->driver->driver_name;
+	ret = driver->auto_attach(dev, context);
+	if (ret >= 0)
+		ret = comedi_device_postconfig(dev);
+
+	if (ret < 0) {
+		dev_warn(hardware_device,
+			 "driver '%s' failed to auto-configure device.\n",
+			 driver->driver_name);
+		mutex_unlock(&dev->mutex);
+		comedi_release_hardware_device(hardware_device);
+	} else {
+		/*
+		 * class_dev should be set properly here
+		 *  after a successful auto config
+		 */
+		dev_info(dev->class_dev,
+			 "driver '%s' has successfully auto-configured '%s'.\n",
+			 driver->driver_name, dev->board_name);
+		mutex_unlock(&dev->mutex);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(comedi_auto_config);
+
+/**
+ * comedi_auto_unconfig() - Unconfigure auto-allocated COMEDI device
+ * @hardware_device: Hardware device previously passed to
+ *                   comedi_auto_config().
+ *
+ * Cleans up and eventually destroys the COMEDI device allocated by
+ * comedi_auto_config() for the same hardware device.  As part of this
+ * clean-up, the low-level COMEDI driver's 'detach' handler will be called.
+ * (The COMEDI device itself will persist in an unattached state if it is
+ * still open, until it is released, and any mmapped buffers will persist
+ * until they are munmapped.)
+ *
+ * This is usually called from a wrapper module in a bus-specific COMEDI
+ * module, which in turn is usually set as the bus device 'remove' function
+ * in the low-level COMEDI driver.
+ */
+void comedi_auto_unconfig(struct device *hardware_device)
+{
+	if (!hardware_device)
+		return;
+	comedi_release_hardware_device(hardware_device);
+}
+EXPORT_SYMBOL_GPL(comedi_auto_unconfig);
+
+/**
+ * comedi_driver_register() - Register a low-level COMEDI driver
+ * @driver: Low-level COMEDI driver.
+ *
+ * The low-level COMEDI driver is added to the list of registered COMEDI
+ * drivers.  This is used by the handler for the "/proc/comedi" file and is
+ * also used by the handler for the %COMEDI_DEVCONFIG ioctl to configure
+ * "legacy" COMEDI devices (for those low-level drivers that support it).
+ *
+ * Returns 0.
+ */
+int comedi_driver_register(struct comedi_driver *driver)
+{
+	mutex_lock(&comedi_drivers_list_lock);
+	driver->next = comedi_drivers;
+	comedi_drivers = driver;
+	mutex_unlock(&comedi_drivers_list_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(comedi_driver_register);
+
+/**
+ * comedi_driver_unregister() - Unregister a low-level COMEDI driver
+ * @driver: Low-level COMEDI driver.
+ *
+ * The low-level COMEDI driver is removed from the list of registered COMEDI
+ * drivers.  Detaches any COMEDI devices attached to the driver, which will
+ * result in the low-level driver's 'detach' handler being called for those
+ * devices before this function returns.
+ */
+void comedi_driver_unregister(struct comedi_driver *driver)
+{
+	struct comedi_driver *prev;
+	int i;
+
+	/* unlink the driver */
+	mutex_lock(&comedi_drivers_list_lock);
+	if (comedi_drivers == driver) {
+		comedi_drivers = driver->next;
+	} else {
+		for (prev = comedi_drivers; prev->next; prev = prev->next) {
+			if (prev->next == driver) {
+				prev->next = driver->next;
+				break;
+			}
+		}
+	}
+	mutex_unlock(&comedi_drivers_list_lock);
+
+	/* check for devices using this driver */
+	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
+		struct comedi_device *dev = comedi_dev_get_from_minor(i);
+
+		if (!dev)
+			continue;
+
+		mutex_lock(&dev->mutex);
+		if (dev->attached && dev->driver == driver) {
+			if (dev->use_count)
+				dev_warn(dev->class_dev,
+					 "BUG! detaching device with use_count=%d\n",
+					 dev->use_count);
+			comedi_device_detach(dev);
+		}
+		mutex_unlock(&dev->mutex);
+		comedi_dev_put(dev);
+	}
+}
+EXPORT_SYMBOL_GPL(comedi_driver_unregister);