char: xillybus: Eliminate redundant wrappers to DMA related calls

The driver was originally written with the assumption that a different
API must be used for DMA-related functions if the device is PCIe based
or if not. Since Xillybus' driver supports devices on a PCIe bus (with
xillybus_pcie) as well as connected directly to the processor (with
xillybus_of), it originally used wrapper functions that ensure that
a different API is used for each.

This patch eliminates the said wrapper functions, as all use the same
dma_* API now. This is most notable by the code deleted in xillybus_pcie.c
and xillybus_of.c.

It also eliminates the OF driver's check for a "dma-coherent" attribute
in the device's OF entry, since this is taken care of by the kernel's
implementation of dma_sync_single_for_*().

There is however still need for one wrapper function, which is merged
from xillybus_pcie.c and xillybus_of.c into xillybus_core.c: The call to
dma_map_single() is wrapped by a function that uses the Managed Device
(devres) framework, in the absence of a relevant function in the current
kernel's API.

Suggested-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Link: https://lore.kernel.org/r/20210929094442.46383-1-eli.billauer@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

char: xillybus: Simplify 'xillybus_init_endpoint()'

Ths first argument of 'xillybus_init_endpoint()' is now useless.
Remove it.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/ba687c1eff5dc8f21422323f57164d06f25d4169.1630083668.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

char: xillybus: Remove usage of remaining deprecated pci_ API

'struct xilly_endpoint' has a 'dev' field which is a 'struct device *' and
a 'pdev' field which is 'struct pci_dev *'.

Both fields are initialized by 'xillybus_init_endpoint()' and in
'xillybus_pcie.c', we have:
xillybus_init_endpoint(pdev, &pdev->dev, &pci_hw);
^ ^
xilly_endpoint.pdev = ___| |___ = xilly_endpoint.dev
So the modification from pci_ to dma_ function is straightforward.

Update all remaining deprecated pci_ function calls to equivalent
dma_ API function.
Switching from 'ep->pdev' to 'ep->dev' makes the transformation
straightforward.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/19d67ac0208a609aef1e28278b3f2477aa714029.1630083668.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

char: xillybus: Remove usage of 'pci_unmap_single()'

'struct xilly_mapping' includes a 'void *device' field which holds,
depending of the context, a 'struct device *' or a 'struct pci_dev *'.

This field is then used with 'pci_umap_single()' in 'xillybus_pcie.c' and
with 'dma_umap_single()' in 'xillybus_of.c'.

In order to remove usage of the deprecated 'pci_unmap_single()' API, turn
the 'void *device' field from 'struct xilly_mapping', into an explicit
'struct device *device' and use 'dma_umap_single()' everywhere.

In order to update 'xillybus_pcie.c', use the 'dev' field instead of the
'pdev' field from the 'struct xilly_endpoint'.
Both fields are initialized by 'xillybus_init_endpoint()' and in
'xillybus_pcie.c', we have:
xillybus_init_endpoint(pdev, &pdev->dev, &pci_hw);
^ ^
xilly_endpoint.pdev = ___| |___ = xilly_endpoint.dev
So the modification from pci_ to dma_ function is straightforward.

While at it, remove a comment that is wrong, because in the case above,
both 'dev' and 'pdev' are not NULL.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/baa3f6c7f009d9c231ae320bf1d568268bfef089.1630083668.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

char: xillybus: Move class-related functions to new xillybus_class.c

This patch is a preparation for adding another related driver, XillyUSB.
In order to share some code between the existing Xillybus driver and the
one to be added, some functions are moved to xillybus_class.c

XILLYBUS_CLASS is added to Kconfig and is common to all drivers in this
group. The relation with the existing XILLYBUS symbol is "select" rather
than "depends on" XILLYBUS_CLASS, or else "make olddefconfig" will silently
turn off XILLYBUS, which is currently enabled in several distributions.

XILLYBUS_CLASS doesn't depend on anything else, hence using it with
"select" poses no risk for a broken configuration.

After the future addition of the XillyUSB module, the tree of symbols
will be as follows:

XILLYBUS_CLASS --+-- XILLYBUS --+-- XILLYBUS_PCIE
| |
| +-- XILLYBUS_OF
|
+-- XILLYUSB

XILLYBUS is for drivers based upon memory registers + DMA-based interfaces,
and it's combined with XILLYBUS_PCIE and/or XILLYBUS_OF.

XILLYUSB is for the USB variant only.

Or a more detailed, bottom-up outline:

* CONFIG_XILLYBUS_PCIE -> xillybus_pcie.c: Functions related to PCIe.
* CONFIG_XILLYBUS_OF -> xillybus_of.c: Functions related to Xillybus as a
peripheral on an FPGA / Processor combo chip.
* CONFIG_XILLYBUS -> xillybus_core.c: Functions that are common to the two
above, mainly access to the peripheral with memory-mapped registers and
DMA.
* CONFIG_XILLYUSB -> xillyusb.c: The driver for the USB variant, accesses
the peripheral through the USB framework.
* CONFIG_XILLYBUS_CLASS -> xillybus_class.c: The new module, which contains
the class and API parts that would otherwise appear both in
xillybus_core.c and xillyusb.c. Contains utility functions for the two
latter.

And since I'm at it, comments on the module names are added in the
Kconfig's help part.

The functions are exported with the non-GPL EXPORT_SYMBOL (a matter of
taste).

Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Link: https://lore.kernel.org/r/20210526100311.56327-2-eli.billauer@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 402

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the smems of the gnu general public license as published by
the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 5 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190111.946565886@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xillybus: Move out of staging

This driver has been functional and stable throughout the year it has spent
in the staging area. It has been patched for minor bugs, coding style issues
and improvements during this period.

This is the second submission of this move-out, after making several style
improvements, as suggested by Dan Carpenter.

Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>