Currently we have a global spi_add_lock which we take when adding new
devices so that we can check that we're not trying to reuse a chip
select that's already controlled. This means that if the SPI device is
itself a SPI controller and triggers the instantiation of further SPI
devices we trigger a deadlock as we try to register and instantiate
those devices while in the process of doing so for the parent controller
and hence already holding the global spi_add_lock. Since we only care
about concurrency within a single SPI bus move the lock to be per
controller, avoiding the deadlock.
This can be easily triggered in the case of spi-mux.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
All these functions have no callers apart from drivers/spi/spi.c. So
drop their declarations in include/linux/spi/spi.h and don't export
them.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211007121415.2401638-5-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>
This patch modified set_cs_timing parameter, no need pass in spi_delay
to set_cs_timing callback.
By the way, we modified the mediatek and tegra114 spi driver to fix build err.
In mediatek spi driver, We have support set absolute time not clk_count,
and call this function in prepare_message not user's API.
Signed-off-by: Mason Zhang <Mason.Zhang@mediatek.com>
Link: https://lore.kernel.org/r/20210804133746.6742-1-Mason.Zhang@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>
As we know, spi core layer has removed spi_set_cs_timing() API.
So this patch moved spi_delay for cs_timing from spi_controller
to spi_device, because cs timing should be set by spi_device but
not controller.
Signed-off-by: Mason Zhang <Mason.Zhang@mediatek.com>
Link: https://lore.kernel.org/r/20210804133716.32040-1-Mason.Zhang@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Fix kernel-doc warning in spi.h by adding the missing kernel-doc entry
and also correct the original comment so that they both indicate the
correct polarity of the flag.
../include/linux/spi/spi.h:673: warning: Function parameter or member 'devm_allocated' not described in 'spi_controller'
Fixes: 794aaf0144 ("spi: Fix use-after-free with devm_spi_alloc_*")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: William A. Kennington III <wak@google.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: linux-spi@vger.kernel.org
Cc: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/20210628210520.5712-1-rdunlap@infradead.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Some controllers like qcom geni need the parent device to be used for
dma mapping, so add a dma_map_dev field and let drivers fill this to be
used as mapping device
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20210625052213.32260-4-vkoul@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Introduce support for ancillary devices, similar to existing
implementation for I2C. This is useful for devices having
multiple chip-selects, for example some microcontrollers
provide a normal SPI interface and a flashing SPI interface.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20210621175359.126729-2-sebastian.reichel@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>
No one seems to be using this global and exported function, so remove it
as it is no longer needed.
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210609071918.2852069-1-gregkh@linuxfoundation.org
Signed-off-by: Mark Brown <broonie@kernel.org>
While fixing undefined behaviour the commit f60d7270c8 ("spi: Avoid
undefined behaviour when counting unused native CSs") missed the case
when all CSs are GPIOs and thus unused_native_cs will be evaluated to
-1 in unsigned representation. This will falsely trigger a condition
in the spi_get_gpio_descs().
Switch to signed types for *_native_cs SPI controller fields to fix above.
Fixes: f60d7270c8 ("spi: Avoid undefined behaviour when counting unused native CSs")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210510131242.49455-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
We can't rely on the contents of the devres list during
spi_unregister_controller(), as the list is already torn down at the
time we perform devres_find() for devm_spi_release_controller. This
causes devices registered with devm_spi_alloc_{master,slave}() to be
mistakenly identified as legacy, non-devm managed devices and have their
reference counters decremented below 0.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 660 at lib/refcount.c:28 refcount_warn_saturate+0x108/0x174
[<b0396f04>] (refcount_warn_saturate) from [<b03c56a4>] (kobject_put+0x90/0x98)
[<b03c5614>] (kobject_put) from [<b0447b4c>] (put_device+0x20/0x24)
r4:b6700140
[<b0447b2c>] (put_device) from [<b07515e8>] (devm_spi_release_controller+0x3c/0x40)
[<b07515ac>] (devm_spi_release_controller) from [<b045343c>] (release_nodes+0x84/0xc4)
r5:b6700180 r4:b6700100
[<b04533b8>] (release_nodes) from [<b0454160>] (devres_release_all+0x5c/0x60)
r8:b1638c54 r7:b117ad94 r6:b1638c10 r5:b117ad94 r4:b163dc10
[<b0454104>] (devres_release_all) from [<b044e41c>] (__device_release_driver+0x144/0x1ec)
r5:b117ad94 r4:b163dc10
[<b044e2d8>] (__device_release_driver) from [<b044f70c>] (device_driver_detach+0x84/0xa0)
r9:00000000 r8:00000000 r7:b117ad94 r6:b163dc54 r5:b1638c10 r4:b163dc10
[<b044f688>] (device_driver_detach) from [<b044d274>] (unbind_store+0xe4/0xf8)
Instead, determine the devm allocation state as a flag on the
controller which is guaranteed to be stable during cleanup.
Fixes: 5e844cc37a ("spi: Introduce device-managed SPI controller allocation")
Signed-off-by: William A. Kennington III <wak@google.com>
Link: https://lore.kernel.org/r/20210407095527.2771582-1-wak@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>
struct spi_transfer is declared twice. One is declared at 24th line.
The blew one is not needed though. Remove the duplicate.
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20210401065904.994121-1-wanjiabing@vivo.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Hi,
The older API used to supply additional device properties for the
devices - so mainly the function device_add_properties() - is going to
be removed. The reason why the API will be removed is because it gives
false impression that the properties are assigned directly to the
devices, which has actually never been the case - the properties have
always been assigned to a software fwnode which was then just directly
linked with the device when the old API was used. By only accepting
device properties instead of complete software nodes, the subsystems
remove any change of taking advantage of the other features the
software nodes have.
The change that is required from the spi subsystem and the drivers is
trivial. Basically only the "properties" member in struct
spi_board_info, which was a pointer to struct property_entry, is
replaced with a pointer to a complete software node.
thanks,
Heikki Krogerus (4):
spi: Add support for software nodes
ARM: pxa: icontrol: Constify the software node
ARM: pxa: zeus: Constify the software node
spi: Remove support for dangling device properties
arch/arm/mach-pxa/icontrol.c | 12 ++++++++----
arch/arm/mach-pxa/zeus.c | 6 +++++-
drivers/spi/spi.c | 21 ++++++---------------
include/linux/spi/spi.h | 7 +++----
4 files changed, 22 insertions(+), 24 deletions(-)
--
2.30.1
base-commit: a38fd87484
Making it possible for the drivers to assign complete
software fwnodes to the devices instead of only the device
properties in those nodes.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210303152814.35070-2-heikki.krogerus@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
The 'delay' field in the spi_transfer struct is meant to replace the
'delay_usecs' field. However some cleanup was required to remove the
uses of 'delay_usecs'. Now that it's been cleaned up, we can remove it
from the kernel tree.
Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210308145502.1075689-10-aardelean@deviqon.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This patch marks dummy transfer by setting dummy_data bit to 1.
Controllers supporting dummy transfer by hardware use this bit field
to skip software transfer of dummy bytes and use hardware dummy bytes
transfer.
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Link: https://lore.kernel.org/r/1608585459-17250-6-git-send-email-skomatineni@nvidia.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Transmit/receive only is a valid SPI mode. For example, the MOSI/TX line
might be missing from an ADC while for a DAC the MISO/RX line may be
optional. This patch adds these two new modes: SPI_NO_TX and
SPI_NO_RX. This way, the drivers will be able to identify if any of
these two lines is missing and to adjust the transfers accordingly.
Signed-off-by: Dragos Bogdan <dragos.bogdan@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201221152936.53873-2-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This change moves all the SPI mode bits into a separate 'spi.h' header in
uAPI. This is meant to re-use these definitions inside the kernel as well
as export them to userspace (via uAPI).
The SPI mode definitions have usually been duplicated between between
'include/linux/spi/spi.h' and 'include/uapi/linux/spi/spidev.h', so
whenever adding a new entry, this would need to be put in both headers.
They've been moved from 'include/linux/spi/spi.h', since that seems a bit
more complete; the bits have descriptions and there is the SPI_MODE_X_MASK.
This change also does a conversion of these bitfields to _BITUL() macro.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201221152936.53873-1-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
SPI driver probing currently comprises two steps, whereas removal
comprises only one step:
spi_alloc_master()
spi_register_controller()
spi_unregister_controller()
That's because spi_unregister_controller() calls device_unregister()
instead of device_del(), thereby releasing the reference on the
spi_controller which was obtained by spi_alloc_master().
An SPI driver's private data is contained in the same memory allocation
as the spi_controller struct. Thus, once spi_unregister_controller()
has been called, the private data is inaccessible. But some drivers
need to access it after spi_unregister_controller() to perform further
teardown steps.
Introduce devm_spi_alloc_master() and devm_spi_alloc_slave(), which
release a reference on the spi_controller struct only after the driver
has unbound, thereby keeping the memory allocation accessible. Change
spi_unregister_controller() to not release a reference if the
spi_controller was allocated by one of these new devm functions.
The present commit is small enough to be backportable to stable.
It allows fixing drivers which use the private data in their ->remove()
hook after it's been freed. It also allows fixing drivers which neglect
to release a reference on the spi_controller in the probe error path.
Long-term, most SPI drivers shall be moved over to the devm functions
introduced herein. The few that can't shall be changed in a treewide
commit to explicitly release the last reference on the controller.
That commit shall amend spi_unregister_controller() to no longer release
a reference, thereby completing the migration.
As a result, the behaviour will be less surprising and more consistent
with subsystems such as IIO, which also includes the private data in the
allocation of the generic iio_dev struct, but calls device_del() in
iio_device_unregister().
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/272bae2ef08abd21388c98e23729886663d19192.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Provide a macro to filter all SPI_MODE_0,1,2,3 mode in one run.
The latest SPI framework will parse the devicetree in following call
sequence: of_register_spi_device() -> of_spi_parse_dt()
So, driver do not need to pars the devicetree and will get prepared
flags in the probe.
On one hand it is good far most drivers. On other hand some drivers need to
filter flags provide by SPI framework and apply know to work flags. This drivers
may use SPI_MODE_X_MASK to filter MODE flags and set own, known flags:
spi->flags &= ~SPI_MODE_X_MASK;
spi->flags |= SPI_MODE_0;
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20201027095724.18654-2-o.rempel@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Use kthread_create_worker() helper to simplify the code. It uses
the kthread worker API the right way. It will eventually allow
to remove the FIXME in kthread_worker_fn() and add more consistency
checks in the future.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20200709065007.26896-1-m.szyprowski@samsung.com
Signed-off-by: Mark Brown <broonie@kernel.org>
On some SPI controllers (like spi-geni-qcom) setting the chip select
is a heavy operation. For instance on spi-geni-qcom, with the current
code, is was measured as taking upwards of 20 us. Even on SPI
controllers that aren't as heavy, setting the chip select is at least
something like a MMIO operation over some peripheral bus which isn't
as fast as a RAM access.
While it would be good to find ways to mitigate problems like this in
the drivers for those SPI controllers, it can also be noted that the
SPI framework could also help out. Specifically, in some situations,
we can see the SPI framework calling the driver's set_cs() with the
same parameter several times in a row. This is specifically observed
when looking at the way the Chrome OS EC SPI driver (cros_ec_spi)
works but other drivers likely trip it to some extent.
Let's solve this by caching the chip select state in the core and only
calling into the controller if there was a change. We check not only
the "enable" state but also the chip select mode (active high or
active low) since controllers may care about both the mode and the
enable flag in their callback.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200629164103.1.Ied8e8ad8bbb2df7f947e3bc5ea1c315e041785a2@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
Add fallback to pio mode in case dma transfer failed with error status
SPI_TRANS_FAIL_NO_START.
If spi client driver want to enable this feature please set xfer->error in
the proper place such as dmaengine_prep_slave_sg() failure detect(but no
any data put into spi bus yet). Besides, add master->fallback checking in
its can_dma() so that spi core could switch to pio next time. Please refer
to spi-imx.c.
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Link: https://lore.kernel.org/r/1592347329-28363-2-git-send-email-yibin.gong@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>
When dealing with a SPI controller driver that is sending more than 1
byte at once (or the entire buffer at once), and the SPI peripheral
driver has requested timestamping for a byte in the middle of the
buffer, we find that spi_take_timestamp_pre never records a "pre"
timestamp.
This happens because the function currently expects to be called with
the "progress" argument >= to what the peripheral has requested to be
timestamped. But clearly there are cases when that isn't going to fly.
And since we can't change the past when we realize that the opportunity
to take a "pre" timestamp has just passed and there isn't going to be
another one, the approach taken is to keep recording the "pre" timestamp
on each call, overwriting the previously recorded one until the "post"
timestamp is also taken.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20200304220044.11193-8-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Currently ACPI firmware description for a SPI device does not have any
method to describe the data buswidth on the board.
So even through the controller and device may support higher modes than
standard SPI, it cannot be assumed that the board does - as such, that
device is limited to standard SPI in such a circumstance.
As a workaround, allow the controller driver supply buswidth override bits,
which are used inform the core code that the controller driver knows the
buswidth supported on that board for that device.
A host controller driver might know this info from DMI tables, for example.
Signed-off-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/1582903131-160033-2-git-send-email-john.garry@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Some SPI master controllers always drive a native chip select when
performing a transfer. Hence when using both native and GPIO chip
selects, at least one native chip select must be left unused, to be
driven when performing transfers with slave devices using GPIO chip
selects.
Currently, to find an unused native chip select, SPI controller drivers
need to parse and process cs-gpios theirselves. This is not only
duplicated in each driver that needs it, but also duplicates part of the
work done later at SPI controller registration time. Note that this
cannot be done after spi_register_controller() returns, as at that time,
slave devices may have been probed already.
Hence add generic support to the SPI subsystem for finding an unused
native chip select. Optionally, this unused native chip select, and all
other in-use native chip selects, can be validated against the maximum
number of native chip selects available on the controller hardware.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200102133822.29346-2-geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>
The API for PTP system timestamping (associating a SPI transaction with
the system time at which it was transferred) is flawed: it assumes that
the xfer->tx_buf pointer will always be present.
This is, of course, not always the case.
So introduce a "progress" variable that denotes how many word have been
transferred.
Fix the Freescale DSPI driver, the only user of the API so far, in the
same patch.
Fixes: b42faeee71 ("spi: Add a PTP system timestamp to the transfer structure")
Fixes: d6b71dfaee ("spi: spi-fsl-dspi: Implement the PTP system timestamping for TCFQ mode")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20191227012417.1057-1-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This change documents the CS setup, host & inactive times. They were
omitted when the fields were added, and were caught by one of the build
bots.
Fixes: 25093bdeb6 ("spi: implement SW control for CS times")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20191023070046.12478-1-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
The way the max delay is computed for this controller, it looks like it is
searching for the max delay from an SPI message a using that.
No idea if this is valid. But this change should support both `delay_usecs`
and the new `delay` data which is of `spi_delay` type.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-17-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This change implements CS control for setup, hold & inactive delays.
The `cs_setup` delay is completely new, and can help with cases where
asserting the CS, also brings the device out of power-sleep, where there
needs to be a longer (than usual), before transferring data.
The `cs_hold` time can overlap with the `delay` (or `delay_usecs`) from an
SPI transfer. The main difference is that `cs_hold` implies that CS will be
de-asserted.
The `cs_inactive` delay does not have a clear use-case yet. It has been
implemented mostly because the `spi_set_cs_timing()` function implements
it. To some degree, this could overlap or replace `cs_change_delay`, but
this will require more consideration/investigation in the future.
All these delays have been added to the `spi_controller` struct, as they
would typically be configured by calling `spi_set_cs_timing()` after an
`spi_setup()` call.
Software-mode for CS control, implies that the `set_cs_timing()` hook has
not been provided for the `spi_controller` object.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-16-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
The initial version of `spi_set_cs_timing()` was implemented with
consideration only for clock-cycles as delay.
For cases like `CS setup` time, it's sometimes needed that micro-seconds
(or nano-seconds) are required, or sometimes even longer delays, for cases
where the device needs a little longer to start transferring that after CS
is asserted.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-15-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
The change introduces the `delay` field to the `spi_transfer` struct as an
`struct spi_delay` type.
This intends to eventually replace `delay_usecs`.
But, since there are many users of `delay_usecs`, this needs some
intermediate work.
A helper called `spi_transfer_delay_exec()` is also added, which maintains
backwards compatibility with `delay_usecs`, by assigning the value to
`delay` if non-zero.
This should maintain backwards compatibility with current users of
`udelay_usecs`.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-9-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This change does a conversion from the `word_delay_usecs` -> `word_delay`
for the `spi_device` struct.
This allows users to specify inter-word delays in other unit types
(nano-seconds or clock cycles), depending on how users want.
The Atmel SPI driver is the only current user of the `word_delay_usecs`
field (from the `spi_device` struct).
So, it needed a slight conversion to use the `word_delay` as an `spi_delay`
struct.
In SPI core, the only required mechanism is to update the `word_delay`
information per `spi_transfer`. This requires a bit more logic than before,
because it needs that both delays be converted to a common unit
(nano-seconds) for comparison.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-8-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
The Spreadtrum SPI driver is the only user of the `word_delay` field in
the `spi_transfer` struct.
This change converts the field to use the `spi_delay` struct. This also
enforces the users to specify the delay unit to be `SPI_DELAY_UNIT_SCK`.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-5-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Since the logic for `spi_delay` struct + `spi_delay_exec()` has been copied
from the `cs_change_delay` logic, it's natural to make this delay, the
first user.
The `cs_change_delay` logic requires that the default remain 10 uS, in case
it is unspecified/unconfigured. So, there is some special handling needed
to do that.
The ADIS library is one of the few users of the new `cs_change_delay`
parameter for an spi_transfer.
The introduction of the `spi_delay` struct, requires that the users of of
`cs_change_delay` get an update. This change also updates the ADIS library.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-4-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
There are plenty of delays that have been introduced in SPI core. Most of
them are in micro-seconds, some need to be in nano-seconds, and some in
clock-cycles.
For some of these delays (related to transfers & CS timing) it may make
sense to have a `spi_delay` struct that abstracts these a bit.
The important element of these delays [for unification] seems to be the
`unit` of the delay.
It looks like micro-seconds is good enough for most people, but every-once
in a while, some delays seem to require other units of measurement.
This change adds the `spi_delay` struct & a `spi_delay_exec()` function
that processes a `spi_delay` object/struct to execute the delay.
It's a copy of the `cs_change_delay` mechanism, but without the default
for 10 uS.
The clock-cycle delay unit is a bit special, as it needs to be bound to an
`spi_transfer` object to execute.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-3-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
SPI is one of the interfaces used to access devices which have a POSIX
clock driver (real time clocks, 1588 timers etc). The fact that the SPI
bus is slow is not what the main problem is, but rather the fact that
drivers don't take a constant amount of time in transferring data over
SPI. When there is a high delay in the readout of time, there will be
uncertainty in the value that has been read out of the peripheral.
When that delay is constant, the uncertainty can at least be
approximated with a certain accuracy which is fine more often than not.
Timing jitter occurs all over in the kernel code, and is mainly caused
by having to let go of the CPU for various reasons such as preemption,
servicing interrupts, going to sleep, etc. Another major reason is CPU
dynamic frequency scaling.
It turns out that the problem of retrieving time from a SPI peripheral
with high accuracy can be solved by the use of "PTP system
timestamping" - a mechanism to correlate the time when the device has
snapshotted its internal time counter with the Linux system time at that
same moment. This is sufficient for having a precise time measurement -
it is not necessary for the whole SPI transfer to be transmitted "as
fast as possible", or "as low-jitter as possible". The system has to be
low-jitter for a very short amount of time to be effective.
This patch introduces a PTP system timestamping mechanism in struct
spi_transfer. This is to be used by SPI device drivers when they need to
know the exact time at which the underlying device's time was
snapshotted. More often than not, SPI peripherals have a very exact
timing for when their SPI-to-interconnect bridge issues a transaction
for snapshotting and reading the time register, and that will be
dependent on when the SPI-to-interconnect bridge figures out that this
is what it should do, aka as soon as it sees byte N of the SPI transfer.
Since spi_device drivers are the ones who'd know best how the peripheral
behaves in this regard, expose a mechanism in spi_transfer which allows
them to specify which word (or word range) from the transfer should be
timestamped.
Add a default implementation of the PTP system timestamping in the SPI
core. This is not going to be satisfactory performance-wise, but should
at least increase the likelihood that SPI device drivers will use PTP
system timestamping in the future.
There are 3 entry points from the core towards the SPI controller
drivers:
- transfer_one: The driver is passed individual spi_transfers to
execute. This is the easiest to timestamp.
- transfer_one_message: The core passes the driver an entire spi_message
(a potential batch of spi_transfers). The core puts the same pre and
post timestamp to all transfers within a message. This is not ideal,
but nothing better can be done by default anyway, since the core has
no insight into how the driver batches the transfers.
- transfer: Like transfer_one_message, but for unqueued drivers (i.e.
the driver implements its own queue scheduling).
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20190905010114.26718-3-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Compiler is not happy about spi_set_cs_timing() prototype.
drivers/spi/spi.c:3016:6: warning: no previous prototype for ‘spi_set_cs_timing’ [-Wmissing-prototypes]
void spi_set_cs_timing(struct spi_device *spi, u8 setup, u8 hold,
^~~~~~~~~~~~~~~~~
Let's add it to the header.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Right now the only way to get the SPI pumping thread bumped up to
realtime priority is for the controller to request it. However it may
be that the controller works fine with the normal priority but
communication to a particular SPI device on the bus needs realtime
priority.
Let's add a way for devices to request realtime priority when they set
themselves up.
NOTE: this will just affect the priority of transfers that end up on
the SPI core's pumping thread. In many cases transfers happen in the
context of the caller so if you need realtime priority for all
transfers you should ensure the calling context is also realtime
priority.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Provide a means for the spi bus driver to report the effectively used
spi clock frequency used for each spi_transfer.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Support setting a delay between cs assert and deassert as
a multiple of spi clock length.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
For some SPI devices that support speed_hz > 1MHz the default 10 us delay
when cs_change = 1 is typically way to long and may result in poor spi bus
utilization.
This patch makes it possible to control the delay at micro or nano second
resolution on a per spi_transfer basis. It even allows an "as fast as
possible" mode with:
xfer.cs_change_delay_unit = SPI_DELAY_UNIT_NSECS;
xfer.cs_change_delay = 0;
The delay code is shared between delay_usecs and cs_change_delay for
consistency and reuse, so in the future this change_delay_unit could also
apply to delay_usec as well.
Note that on slower SOCs/CPU actually reaching ns deasserts on cs is not
realistic as the gpio overhead alone (without any delays added ) may
already leave cs deasserted for more than 1us - at least on a raspberry pi.
But at the very least this way we can keep it as short as possible.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This patch changes mode and mode_bits from u16 to u32 to allow more
mode configurations.
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This let SPI clients check if the controller supports a particular word
width. drivers/gpu/drm/tinydrm/mipi-dbi.c will use this to determine if
the controller supports 16-bit for RGB565 pixels. If it doesn't it will
swap the bytes before transfer on little endian machines.
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This patch creates set_cs_timing SPI master optional method for
SPI masters to implement configuring CS timing if applicable.
This patch also creates spi_cs_timing accessory for SPI clients to
use for requesting SPI master controllers to configure device requested
CS setup time, hold time and inactive delay.
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Geert points out that I confused the min/max arguments that are
reversed between SPI_BPW_RANGE_MASK() and GENMASK(). This time
I have verified the result of the macro after fixing the arguments.
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: eefffb42f6 ("spi: work around clang bug in SPI_BPW_RANGE_MASK()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Clang-8 evaluates both sides of a ?: expression to check for
valid arithmetic even in the side that is never taken. This
results in a build warning:
drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
.bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
^~~~~~~~~~~~~~~~~~~~~~~~~
Change the implementation to use the GENMASK() macro that does
what we want here but does not have a problem with the shift
count overflow.
Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Some devices are slow and cannot keep up with the SPI bus and therefore
require a short delay between words of the SPI transfer.
The example of this that I'm looking at is a SAMA5D2 with a minimum SPI
clock of 400kHz talking to an AVR-based SPI slave. The AVR cannot put
bytes on the bus fast enough to keep up with the SoC's SPI controller
even at the lowest bus speed.
This patch introduces the ability to specify a required inter-word
delay for SPI devices. It is up to the controller driver to configure
itself accordingly in order to introduce the requested delay.
Note that, for spi_transfer, there is already a field word_delay that
provides similar functionality. This field, however, is specified in
clock cycles (and worse, SPI controller cycles, not SCK cycles); that
makes this value dependent on the master clock instead of the device
clock for which the delay is intended to provide some relief. This
patch leaves this old word_delay in place and provides a time-based
word_delay_us alongside it; the new field fits in the struct padding
so struct size is constant. There is only one in-kernel user of the
word_delay field and presumably that driver could be reworked to use
the time-based value instead.
The time-based delay is limited to 8 bits as these delays are intended
to be short. The SAMA5D2 that I've tested this on limits delays to a
maximum of ~100us, which is already many word-transfer periods even at
the minimum transfer speed supported by the controller.
Signed-off-by: Jonas Bonn <jonas@norrbonn.se>
CC: Mark Brown <broonie@kernel.org>
CC: Rob Herring <robh+dt@kernel.org>
CC: Mark Rutland <mark.rutland@arm.com>
CC: linux-spi@vger.kernel.org
CC: devicetree@vger.kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Commit 412e603732 ("spi: core: avoid waking pump thread from spi_sync
instead run teardown delayed") introduced regressions on some boards,
apparently connected to spi_mem not triggering shutdown properly any
more. Since we've thus far been unable to figure out exactly where the
breakage is revert the optimisation for now.
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: kernel@martin.sperl.org
This augments the SPI core to optionally use GPIO descriptors
for chip select on a per-master-driver opt-in basis.
Drivers using this will rely on the SPI core to look up
GPIO descriptors associated with the device, such as
when using device tree or board files with GPIO descriptor
tables.
When getting descriptors from the device tree, this will in
turn activate the code in gpiolib that was
added in commit 6953c57ab1
("gpio: of: Handle SPI chipselect legacy bindings")
which means that these descriptors are aware of the active
low semantics that is the default for SPI CS GPIO lines
and we can assume that all of these are "active high" and
thus assign SPI_CS_HIGH to all CS lines on the DT path.
The previously used gpio_set_value() would call down into
gpiod_set_raw_value() and ignore the polarity inversion
semantics.
It seems like many drivers go to great lengths to set up the
CS GPIO line as non-asserted, respecting SPI_CS_HIGH. We pull
this out of the SPI drivers and into the core, and by simply
requesting the line as GPIOD_OUT_LOW when retrieveing it from
the device and relying on the gpiolib to handle any inversion
semantics. This way a lot of code can be simplified and
removed in each converted driver.
The end goal after dealing with each driver in turn, is to
delete the non-descriptor path (of_spi_register_master() for
example) and let the core deal with only descriptors.
The different SPI drivers have complex interactions with the
core so we cannot simply change them all over, we need to use
a stepwise, bisectable approach so that each driver can be
converted and fixed in isolation.
This patch has the intended side effect of adding support for
ACPI GPIOs as it starts relying on gpiod_get_*() to get
the GPIO handle associated with the device.
Cc: Linuxarm <linuxarm@huawei.com>
Acked-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Fangjian (Turing) <f.fangjian@huawei.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add flags for Octal mode I/O data transfer
Required for the SPI controller which can do the data transfer (TX/RX)
on 8 data lines e.g. NXP FlexSPI controller.
SPI_TX_OCTAL: transmit with 8 wires
SPI_RX_OCTAL: receive with 8 wires
Signed-off-by: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Some devices such as the TPO TPG110 display panel require
a "high-impedance turn-around", in effect a clock cycle after
switching the line from output to input mode.
Support this in the GPIO driver to begin with. Other driver
may implement it if they can, it is unclear if this can
be achieved with anything else than GPIO bit-banging.
Cc: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This attribute works the same was as the identically named attribute
for PCI, AMBA, and platform devices. For reference, see:
commit 3cf3857134 ("ARM: 8256/1: driver coamba: add device binding
path 'driver_override'")
commit 3d713e0e38 ("driver core: platform: add device binding path
'driver_override'")
commit 782a985d7a ("PCI: Introduce new device binding path using
pci_dev.driver_override")
If the name of a driver is written to this attribute, then the device
will bind to the named driver and only the named driver.
The device will bind to the driver even if the driver does not list the
device in its id table. This behavior is different than the driver's
bind attribute, which only allows binding to devices that are listed as
supported by the driver.
It can be used to bind a generic driver, like spidev, to a device.
Signed-off-by: Trent Piepho <tpiepho@impinj.com>
Reviewed-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Tested-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
The of_find_spi_device_by_node() helper function is useful for other
modules too. Export the funciton as GPL like all other spi helper
functions and make it available if CONFIG_OF is enabled, because it isn't
related to the CONFIG_OF_DYNAMIC context. Finally add a stub if
CONFIG_OF isn't enabled, so others must not care about it.
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Use the appropriate SPDX license identifier and drop the previous
license text.
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
This provides a SPI operation mode which changes chip select after every
word, used by some devices such as ADCs and DACs.
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Merge tag 'spi-cs-word' into spi-4.20
spi: Provide SPI_CS_WORD
This provides a SPI operation mode which changes chip select after every
word, used by some devices such as ADCs and DACs.
This adds a new SPI mode flag, SPI_CS_WORD, that is used to indicate
that a SPI device requires the chip select to be toggled after each
word that is transferred.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
For some SPI controllers, after each word size (specified by bits_per_word)
transimission, the hardware need some delay to make sure the slave has enough
time to receive the whole data.
So introducing one new 'word_delay' field of struct spi_tansfer for slave
devices to set this inter word delay time.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This API has been replaced by the spi_mem_xx() one, its only user
(spi-nor) has been converted to spi_mem_xx() and all SPI controller
drivers that were implementing the ->spi_flash_xxx() hooks are also
implementing the spi_mem ones. So we can safely get rid of this API.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@exceet.de>
Tested-by: Frieder Schrempf <frieder.schrempf@exceet.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Some controllers are exposing high-level interfaces to access various
kind of SPI memories. Unfortunately they do not fit in the current
spi_controller model and usually have drivers placed in
drivers/mtd/spi-nor which are only supporting SPI NORs and not SPI
memories in general.
This is an attempt at defining a SPI memory interface which works for
all kinds of SPI memories (NORs, NANDs, SRAMs).
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@exceet.de>
Tested-by: Frieder Schrempf <frieder.schrempf@exceet.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Now struct spi_master is used for both SPI master and slave controllers,
it makes sense to rename it to struct spi_controller, and replace
"master" by "controller" where appropriate.
For now this conversion is done for SPI core infrastructure only.
Wrappers are provided for backwards compatibility, until all SPI drivers
have been converted.
Noteworthy details:
- SPI_MASTER_GPIO_SS is retained, as it only makes sense for SPI
master controllers,
- spi_busnum_to_master() is retained, as it looks up masters only,
- A new field spi_device.controller is added, but spi_device.master is
retained for compatibility (both are always initialized by
spi_alloc_device()),
- spi_flash_read() is used by SPI masters only.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add support for registering SPI slave controllers using the existing SPI
master framework:
- SPI slave controllers must use spi_alloc_slave() instead of
spi_alloc_master(), and should provide an additional callback
"slave_abort" to abort an ongoing SPI transfer request,
- SPI slave controllers are added to a new "spi_slave" device class,
- SPI slave handlers can be bound to the SPI slave device represented
by an SPI slave controller using a DT child node named "slave",
- Alternatively, (un)binding an SPI slave handler to the SPI slave
device represented by an SPI slave controller can be done by
(un)registering the slave device through a sysfs virtual file named
"slave".
From the point of view of an SPI slave protocol handler, an SPI slave
controller looks almost like an ordinary SPI master controller. The only
exception is that a transfer request will block on the remote SPI
master, and may be cancelled using spi_slave_abort().
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add an interface analogous to ->can_dma() for spi_flash_read()
interface. This will enable SPI controller drivers to inform SPI core
when not to do DMA mappings.
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Invoke the proper function while initializing
a dynamically allocated spi_message to avoid
NULL pointer dereference during resources deallocation.
Signed-off-by: Emiliano Ingrassia <ingrassia@epigenesys.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Generic device properties support statically defined property sets. For
them to be usable, we need to attach these property sets before devices
are registered and probed. Allowing to attach property list to
spi_board_info structure will allow non-ACPI non-DT boards switch to using
generic properties and get rid of custom platform data.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Some SPI masters require slave selection before the transfer
can begin [1]. The SPI framework currently selects the chip using
either 1) the internal CS mechanism or 2) the GPIO CS, but not both.
This patch adds a new master->flags define to indicate both the GPIO
CS and the internal chip select mechanism should be used.
Tested On:
Altera CycloneV development kit
Compile tested for build errors on x86_64 (allyesconfigs)
[1] DesignWare dw_apb_ssi Databook, Version 3.20a (page 39)
Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Simplify spi_write() and spi_read() using the spi_sync_transfer()
helper.
This requires moving spi_sync_transfer() up.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Recently a maximum transfer size was was introduced in struct spi_master.
However there are also spi controllers with a maximum message size, e.g.
fsl-espi has a max message size of 64KB.
Introduce a hook max_message_size to deal with such limitations.
Also make sure that spi_max_transfer_size doesn't return greater values
than spi_max_message_size, even if hook max_transfer_size is not set.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The current SPI code attempts to use bus_lock_mutex for two purposes. One
is to implement spi_bus_lock() which grants exclusive access to the bus.
The other is to serialize access to the physical hardware. This duplicate
purpose causes confusion which leads to cases where access is not locked
when a caller holds the bus lock mutex. Fix this by splitting out the I/O
functionality into a new io_mutex.
This means taking both mutexes in the DMA path, replacing the existing
mutex with the new I/O one in the message pump (the mutex now always
being taken in the message pump) and taking the bus lock mutex in
spi_sync(), allowing __spi_sync() to have no mutex handling.
While we're at it hoist the mutex further up the message pump before we
power up the device so that all power up/down of the block is covered by
it and there are no races with in-line pumping of messages.
Reported-by: Rich Felker <dalias@libc.org>
Tested-by: Rich Felker <dalias@libc.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Few SPI devices provide accelerated read interfaces to read from
SPI-NOR flash devices. These hardwares also support DMA to transfer data
from flash to memory either via mem-to-mem DMA or dedicated slave DMA
channels. Hence, add support for DMA in order to improve throughput and
reduce CPU load.
Use spi_map_buf() to get sg table for the buffer and pass it to SPI
driver.
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
If hook spi_flash_read is implemented the fast flash read feature
is enabled for all devices attached to the respective master.
In most cases there is just one flash chip, however there are also
devices with more than one flash chip, namely some WiFi routers.
Then the fast flash read feature can be used for the first chip only.
OpenWRT implemented an own handling of this case, using controller_data
element of spi_device to hold the information whether fast flash read
can be used for a device.
This patch adds hook flash_read_supported to spi_master which is
used to extend spi_flash_read_supported() by checking whether the
fast flash read feature can be used for a specific spi_device.
If the hook is not implemented the default behavior is to allow
fast flash read for all devices (if spi_flash_read is implemented).
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The kernel-doc has to be just before the structure definition but the one
for struct spi_replaced_transfers was before a structure declaration and
that confuses kernel-doc which complains with the following build error:
.//include/linux/spi/spi.h:933: error: Cannot parse struct or union!
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Fixes docbook parsing error because documentation
is not directly followed by the structure, but typedef
used in structure.
Reordering should solve that issue.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
In addition to providing direct access to SPI bus, some spi controller
hardwares (like ti-qspi) provide special port (like memory mapped port)
that are optimized to improve SPI flash read performance.
This means the controller can automatically send the SPI signals
required to read data from the SPI flash device.
For this, SPI controller needs to know flash specific information like
read command to use, dummy bytes and address width.
Introduce spi_flash_read() interface to support accelerated read
over SPI flash devices. SPI master drivers can implement this callback to
support interfaces such as memory mapped read etc. m25p80 flash driver
and other flash drivers can call this make use of such interfaces. The
interface should only be used with SPI flashes and cannot be used with
other SPI devices.
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add spi_split_transfers_maxsize method that splits
spi_transfers transparently into multiple transfers
that are below the given max-size.
This makes use of the spi_res framework via
spi_replace_transfers to allocate/free the extra
transfers as well as reverting back the changes applied
while processing the spi_message.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add the spi_replace_transfers method that can get used
to replace some spi_transfers from a spi_message with other
transfers.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
SPI resource management framework used while processing a spi_message
via the spi-core.
The basic idea is taken from devres, but as the allocation may happen
fairly frequently, some provisioning (in the form of an unused spi_device
pointer argument to spi_res_alloc) has been made so that at a later stage
we may implement reuse objects allocated earlier avoiding the repeated
allocation by keeping a cache of objects that we can reuse.
This framework can get used for:
* rewriting spi_messages
* to fullfill alignment requirements of the spi_master HW
* to fullfill transfer length requirements
(e.g: transfers need to be less than 64k)
* consolidate spi_messages with multiple transfers into a single transfer
when the total transfer length is below a threshold.
* reimplement spi_unmap_buf without explicitly needing to check if it has
been mapped
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
