spi: pxa2xx: Update DMA mapping and using logic in the documentation

Update DMA mapping and using logic in the documentation to follow what
the code does.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231208170436.3309648-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: pxa2xx: Use inclusive language

Replace master/slave by host/peripheral language in the documentation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231208170436.3309648-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: correct spelling

Correct spelling problems for Documentation/spi/ as reported
by codespell.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20230127064005.1558-28-rdunlap@infradead.org
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: pxa2xx_spi: Convert to use GPIO descriptors

This converts the PXA2xx SPI driver to use GPIO descriptors
exclusively to retrieve GPIO chip select lines.

The device tree and ACPI paths of the driver already use
descriptors, hence ->use_gpio_descriptors is already set and
this codepath is well tested.

Convert all the PXA boards providing chip select GPIOs as
platform data and drop the old GPIO chipselect handling in
favor of the core managing it exclusively.

Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220125005836.494807-1-linus.walleij@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: pxa2xx: Get rid of unused enable_loopback member

There is no user of the enable_loopback member in the struct pxa2xx_spi_chip.
Remote this legacy member completely.

The mentioned in the documentation the testing phase can be performed with
spidev_test tool.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211123192723.44537-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: pxa2xx: Get rid of unused ->cs_control()

Since the last user of the custom ->cs_control() gone, we may get rid of
this legacy API completely.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211123192723.44537-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: pxa2xx: Update documentation to point out that it's outdated

Update documentation by pointing out that it's applicable mostly
for a legacy platform. While at it, add couple of points with regard
to ACPI, Device Tree, and automatic DMA enablement.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210517140351.901-9-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: docs: convert to ReST and add it to the kABI bookset

While there's one file there with briefily describes the uAPI,
the documentation was written just like most subsystems: focused
on kernel developers. So, add it together with driver-api books.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> # for iio
Signed-off-by: Jonathan Corbet <corbet@lwn.net>