spi: spi-summary.rst: fix underline length

The change to use "target" requires an underline to be extended by
one more character to fix a documentation build warning:

Documentation/spi/spi-summary.rst:274: WARNING: Title underline too short.
Declare target Devices
^^^^^^^^^^^^^^^^^^^^^

Fixes: hash ("spi: Update the "master/slave" terminology in documentation")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Dhruva Gole <d-gole@ti.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: linux-spi@vger.kernel.org
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Link: https://msgid.link/r/20240216051637.10920-1-rdunlap@infradead.org
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: Update the "master/slave" terminology in documentation

Update the master/slave terminology wherever possible to adopt usage of
the controller/host/target. Some parts have been left untouched because
they were sysfs entries and will probably end up being inaccurate if
simply replaced here.

Signed-off-by: Dhruva Gole <d-gole@ti.com>
Link: https://msgid.link/r/20240215085404.1711976-1-d-gole@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation: spi: Update documentation for renaming "master" to "controller"

In commit 8caab75fd2c2 ("spi: Generalize SPI "master" to "controller"")
some functions and struct members were renamed. Adapt the documentation
accordingly.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/3d643e22cacff12d3918ad5224baa1d01813d03b.1707324794.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: docs: adjust summary to CONFIG_SYSFS_DEPRECATED removal

With commit 721da5cee9d4 ("driver core: remove CONFIG_SYSFS_DEPRECATED and
CONFIG_SYSFS_DEPRECATED_V2"), ./scripts/checkkconfigsymbols.py indicated
an unresolved reference to the config SYSFS_DEPRECATED in the SPI summary
documentation.

Simply, delete the sentence referring to the removed config there. Also
update the documentation, as these sys/class entries should always be
symlinks, as the commit message of the commit above suggests.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230314075609.5232-1-lukas.bulwahn@gmail.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: Remove unused function spi_busnum_to_master()

The last user is gone since commit

2962db71c703 ("staging/fbtft: Remove fbtft_device")

in 2019.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211007121415.2401638-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: docs: update info about 'delay_usecs'

The 'delay_usecs' field is no longer present on the spi_transfer struct.
This change updates the doc to mention the usage of the (relatively) new
'delay' field.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210308145502.1075689-11-aardelean@deviqon.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>