The behavior of an SPI controller data output line (SDO or MOSI or COPI
(Controller Output Peripheral Input) for disambiguation) is usually not
specified when the controller is not clocking out data on SCLK edges.
However, there do exist SPI peripherals that require specific MOSI line
state when data is not being clocked out of the controller.
Conventional SPI controllers may set the MOSI line on SCLK edges then bring
it low when no data is going out or leave the line the state of the last
transfer bit. More elaborated controllers are capable to set the MOSI idle
state according to different configurable levels and thus are more suitable
for interfacing with demanding peripherals.
Add SPI mode bits to allow peripherals to request explicit MOSI idle state
when needed.
When supporting a particular MOSI idle configuration, the data output line
state is expected to remain at the configured level when the controller is
not clocking out data. When a device that needs a specific MOSI idle state
is identified, its driver should request the MOSI idle configuration by
setting the proper SPI mode bit.
Acked-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Tested-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://patch.msgid.link/9802160b5e5baed7f83ee43ac819cb757a19be55.1720810545.git.marcelo.schmitt@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
There are no more users of the deprecated is_dma_mapped in struct
spi_message so it can be removed.
References in documentation and comments are also removed.
A few similar checks if xfer->tx_dma or xfer->rx_dma are not NULL are
also removed since these are now guaranteed to be NULL because they
were previously set only if is_dma_mapped was true.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://msgid.link/r/20240325-spi-remove-is_dma_mapped-v2-1-d08d62b61f1c@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>
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>
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>
With commit 721da5cee9 ("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>
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>
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>
