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
It's also a slave controller driver now, calling it "master" is slightly
misleading.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>
Since direct mapping descriptors usually the same lifetime as the SPI
MEM device adding devm_ variants of the spi_mem_dirmap_{create,destroy}()
should greatly simplify error/remove path of spi-mem drivers making use
of the direct mapping API.
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.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>
Pull MMC updates from Ulf Hansson:
"This time, this pull request contains changes crossing subsystems and
archs/platforms, which is mainly because of a bigger modernization of
moving from legacy GPIO to GPIO descriptors for MMC (by Linus
Walleij).
Additionally, once again, I am funneling changes to
drivers/misc/cardreader/* and drivers/memstick/* through my MMC tree,
mostly due to that we lack a maintainer for these.
Summary:
MMC core:
- Cleanup BKOPS support
- Introduce MMC_CAP_SYNC_RUNTIME_PM
- slot-gpio: Delete legacy slot GPIO handling
MMC host:
- alcor: Add new mmc host driver for Alcor Micro PCI based cardreader
- bcm2835: Several improvements to better recover from errors
- jz4740: Rework and fixup pre|post_req support
- mediatek: Add support for SDIO IRQs
- meson-gx: Improve clock phase management
- meson-gx: Stop descriptor on errors
- mmci: Complete the sbc error path by sending a stop command
- renesas_sdhi/tmio: Fixup reset/resume operations
- renesas_sdhi: Add support for r8a774c0 and R7S9210
- renesas_sdhi: Whitelist R8A77990 SDHI
- renesas_sdhi: Fixup eMMC HS400 compatibility issues for H3 and M3-W
- rtsx_usb_sdmmc: Re-work card detection/removal support
- rtsx_usb_sdmmc: Re-work runtime PM support
- sdhci: Fix timeout loops for some variant drivers
- sdhci: Improve support for error handling due to failing commands
- sdhci-acpi/pci: Disable LED control for Intel BYT-based controllers
- sdhci_am654: Add new SDHCI variant driver to support TI's AM654 SOCs
- sdhci-of-esdhc: Add support for eMMC HS400 mode
- sdhci-omap: Fixup reset support
- sdhci-omap: Workaround errata regarding SDR104/HS200 tuning failures
- sdhci-msm: Fixup sporadic write transfers issues for SDR104/HS200
- sdhci-msm: Fixup dynamical clock gating issues
- various: Complete converting all hosts into using slot GPIO descriptors
Other:
- Move GPIO mmc platform data for mips/sh/arm to GPIO descriptors
- Add new Alcor Micro cardreader PCI driver
- Support runtime power management for memstick rtsx_usb_ms driver
- Use USB remote wakeups for card detection for rtsx_usb misc driver"
* tag 'mmc-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc: (99 commits)
mmc: mediatek: Add MMC_CAP_SDIO_IRQ support
mmc: renesas_sdhi_internal_dmac: Whitelist r8a774c0
dt-bindings: mmc: renesas_sdhi: Add r8a774c0 support
mmc: core: Cleanup BKOPS support
mmc: core: Drop redundant check in mmc_send_hpi_cmd()
mmc: sdhci-omap: Workaround errata regarding SDR104/HS200 tuning failures (i929)
dt-bindings: sdhci-omap: Add note for cpu_thermal
mmc: sdhci-acpi: Disable LED control for Intel BYT-based controllers
mmc: sdhci-pci: Disable LED control for Intel BYT-based controllers
mmc: sdhci: Add quirk to disable LED control
mmc: mmci: add variant property to set command stop bit
misc: alcor_pci: fix spelling mistake "invailid" -> "invalid"
mmc: meson-gx: add signal resampling
mmc: meson-gx: align default phase on soc vendor tree
mmc: meson-gx: remove useless lock
mmc: meson-gx: make sure the descriptor is stopped on errors
mmc: sdhci_am654: Add Initial Support for AM654 SDHCI driver
dt-bindings: mmc: sdhci-of-arasan: Add deprecated message for AM65
dt-bindings: mmc: sdhci-am654: Document bindings for the host controllers on TI's AM654 SOCs
mmc: sdhci-msm: avoid unused function warning
...
Switch the SPI MMC driver to use GPIO descriptors internally
and just look those up using the standard slot GPIO
functions mmc_gpiod_request_cd() and mmc_gpiod_request_ro().
Make sure to request index 0 and 1 in accordance with the
SPI MMC DT binding, and add the same GPIOs in machine
descriptor tables on all boards that use SPI MMC in
board files.
The lines are flagged as GPIO_ACTIVE_[LOW|HIGH] as that is
what they are, and since we can now rely on the descriptors
to have the right polarity, we set the
"override_active_level" to false in mmc_gpiod_request_cd()
and mmc_gpiod_request_ro().
Cc: Hartley Sweeten <hsweeten@visionengravers.com> # Vision EP9307
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.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>
Most modern SPI controllers can directly map a SPI memory (or a portion
of the SPI memory) in the CPU address space. Most of the time this
brings significant performance improvements as it automates the whole
process of sending SPI memory operations every time a new region is
accessed.
This new API allows SPI memory drivers to create direct mappings and
then use them to access the memory instead of using spi_mem_exec_op().
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
When defining spi_mem_op templates we don't necessarily know the size
that will be passed when the template is actually used, and basing the
supports_op() check on op->data.nbytes to know whether there will be
data transferred for a specific operation is this not possible.
Add SPI_MEM_NO_DATA to the spi_mem_data_dir enum so that we can base
our checks on op->data.dir instead of op->data.nbytes.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Tested on an OLPC XO-1.75 machine, where the Embedded Controller happens
to be a SPI master.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
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>
Mark writes:
"spi: Fixes for v4.19
Quite a few fixes for the Renesas drivers in here, plus a fix for the
Tegra driver and some documentation fixes for the recently added
spi-mem code. The Tegra fix is relatively large but fairly
straightforward and mechanical, it runs on probe so it's been
reasonably well covered in -next testing."
* tag 'spi-fix-v4.19-rc5' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
spi: spi-mem: Move the DMA-able constraint doc to the kerneldoc header
spi: spi-mem: Add missing description for data.nbytes field
spi: rspi: Fix interrupted DMA transfers
spi: rspi: Fix invalid SPI use during system suspend
spi: sh-msiof: Fix handling of write value for SISTR register
spi: sh-msiof: Fix invalid SPI use during system suspend
spi: gpio: Fix copy-and-paste error
spi: tegra20-slink: explicitly enable/disable clock
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>
We'd better have that documented in the kerneldoc header, so that it's
exposed to the doc generated by Sphinx.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add a description for spi_mem_op.data.nbytes to the kerneldoc header.
Fixes: c36ff266dc ("spi: Extend the core to ease integration of SPI memory controllers")
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
