Calls to optional subsystems cannot be made indiscriminately.
Enclose all of the usb helper functions inside
#if IS_ENABLED(CONFIG_USB)
to fix these build errors.

(The pci helper functions are OK since there are stubs in
linux/pci.h for the called functions when PCI is not enabled.
Possibly the same could be done for the called USB functions.)

ERROR: "usb_deregister" [drivers/staging/comedi/comedi.ko] undefined!
ERROR: "usb_register_driver" [drivers/staging/comedi/comedi.ko] undefined!

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce the module_comedi_usb_driver macro, and the
associated register/unregister functions, which is a
convenience macro for comedi usb driver modules similar
to module_platform_driver. It is intended to be used by
drivers where the init/exit section does nothing but
register/unregister the comedi driver and associated usb
driver. By using this macro it is possible to eliminate
a few lines of boilerplate code per comedi usb driver.

Also, when registering the usb driver check for failure
and unregister the comedi driver.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce the module_comedi_pci_driver macro, and the
associated register/unregister functions, which is a
convenience macro for comedi pci driver modules similar
to module_platform_driver. It is intended to be used by
drivers where the init/exit section does nothing but
register/unregister the comedi driver and associated pci
driver. By using this macro it is possible to eliminate
a few lines of boilerplate code per comedi pci driver.

Add a check to make sure that the pci_driver->name is
set. Once all the comedi pci drivers have been fixed this
will be removed.

Also, when registering the pci driver check for failure
and unregister the comedi driver.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For comedi subdevices that support asynchronous transfer commands, the
initial buffer size and maximum buffer size for the transfer are both
set to 64 KiB when the comedi device is "attached" to the hardware
device.  For many applications with reasonable fast sample rates and
slow user-space (e.g. Python) these sizes are a bit too small.

A task with CAP_SYS_ADMIN privileges can change the maximum buffer size
for a comedi subdevice with an ioctl call or by writing to a device
attribute file in sysfs, but that's not very convenient.  For comedi
devices attached during system startup, this could be done by a start-up
script, but for hot-plugged devices it would require scripts run by udev
rules, etc.

Rather than use hardwired values, this patch introduces a couple of
module parameters to set the defaults for the initial buffer size
(comedi_default_buf_size_kb) and maximum buffer size
(comedi_default_buf_maxsize_kb).  These values are applied in place of
the previous hard-wired values when the comedi device is "attached".
The module parameter values are in units of KiB for consistency with the
existing device attribute files.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

comedi_auto_config() only needs to consider a single struct
comedi_driver object, but it currently calls comedi_device_attach()
which looks at all struct comedi_driver objects registered with the
Comedi core.

Instead, call the recently added comedi_auto_config_helper() with a new
wrapper comedi_auto_config_wrapper() to mimic the effect of
comedi_device_attach() for a single struct comedi_driver.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pass a pointer to the struct comedi_driver to comedi_auto_config()
instead of the driver name.  comedi_auto_config() will be changed to
make use of this.  It currently calls comedi_device_attach() which
examines the whole list of struct comedi_driver objects.  It will be
changed to restrict itself to just the supplied struct comedi_driver
object.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The Comedi auto-configuration mechanism used to bind hardware devices to
comedi devices automatically is pretty kludgy.  It fakes a "manual"
configuration of the comedi device as though the COMEDI_DEVCONFIG ioctl
(or the 'comedi_config' utility) were used.  In particular, the
low-level comedi driver's '->attach()' routine is called with a pointer
to the struct comedi_device being attached and a pointer to a 'struct
devconfig' containing a device name string and a few integer options to
help the attach routine locate the device being attached.  In the case
of PCI devices, these integer options are the PCI bus and slot numbers.
In the case of USB devices, there are no integer options and it relies
more on pot luck to attach the correct device.

This patch adds a couple of bus-type-specific attach routine hooks to
the struct comedi_driver, which a low-level driver can optionally fill
in if it supports auto-configuration.

A low-level driver that supports auto-configuration of {PCI,USB} devices
calls the existing comedi_{pci,usb}_auto_config() when it wishes to
auto-configure a freshly probed device (maybe after loading firmware).
This will call the new '->attach_{pci,usb}()' hook if the driver has
defined it, otherwise it will fall back to calling the '->attach()' hook
as before.  The '->attach_{pci,usb}()' hook gets a pointer to the struct
comedi_device and a pointer to the struct {pci_dev,usb_interface} and
can figure out the {PCI,USB} device details for itself.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Split the post-config part of comedi_device_attach() into new function
comedi_device_postconfig() and rearrange the rest of the function a bit.

The new comedi_device_postconfig() function will be called by some new
bus-type-specific auto-attach functions.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The comedi_usb_auto_config() and comedi_usb_auto_unconfig() functions
currently take a 'struct usb_device *'.  It makes more sense to pass a
'struct usb_interface *' to allow for composite USB devices.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

comedi_auto_config() associates a Comedi minor device number with an
auto-configured hardware device and comedi_auto_unconfig() disassociates
it.  Currently, these use the hardware device's private data pointer to
point to some allocated storage holding the minor device number.  This
is a bit of a waste of the hardware device's private data pointer,
preventing it from being used for something more useful by the low-level
comedi device drivers.  For example, it would make more sense if
comedi_usb_auto_config() was passed a pointer to the struct
usb_interface instead of the struct usb_device, but this cannot be done
currently because the low-level comedi drivers already use the private
data pointer in the struct usb_interface for something more useful.

This patch stops the comedi core hijacking the hardware device's private
data pointer.  Instead, comedi_auto_config() stores a pointer to the
hardware device's struct device in the struct comedi_device_file_info
associated with the minor device number, and comedi_auto_unconfig()
calls new function comedi_find_board_minor() to recover the minor device
number associated with the hardware device.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>