spi: bcm2835aux: Use helper function devm_clk_get_enabled()

Since commit 7ef9651e9792 ("clk: Provide new devm_clk helpers for prepared
and enabled clocks"), devm_clk_get() and clk_prepare_enable() can now be
replaced by devm_clk_get_enabled() when driver enables (and possibly
prepares) the clocks for the whole lifetime of the device. Moreover, it is
no longer necessary to unprepare and disable the clocks explicitly.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Li Zetao <lizetao1@huawei.com>
Link: https://lore.kernel.org/r/20230823133938.1359106-8-lizetao1@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: Do not check for 0 return after calling platform_get_irq()

It is not possible for platform_get_irq() to return 0. Use the
return value from platform_get_irq().

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com> #
Link: https://lore.kernel.org/r/20230802093238.975906-1-ruanjinjie@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: switch to use modern name

Change legacy name master to modern name host or controller.

No functional changed.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20230728093221.3312026-7-yangyingliang@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230714174955.4064174-1-robh@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: Replace all spi->chip_select and spi->cs_gpiod references with function call

Supporting multi-cs in spi drivers would require the chip_select & cs_gpiod
members of struct spi_device to be an array. But changing the type of these
members to array would break the spi driver functionality. To make the
transition smoother introduced four new APIs to get/set the
spi->chip_select & spi->cs_gpiod and replaced all spi->chip_select and
spi->cs_gpiod references with get or set API calls.
While adding multi-cs support in further patches the chip_select & cs_gpiod
members of the spi_device structure would be converted to arrays & the
"idx" parameter of the APIs would be used as array index i.e.,
spi->chip_select[idx] & spi->cs_gpiod[idx] respectively.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Acked-by: Heiko Stuebner <heiko@sntech.de> # Rockchip drivers
Reviewed-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org> # Aspeed driver
Reviewed-by: Dhruva Gole <d-gole@ti.com> # SPI Cadence QSPI
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com> # spi-stm32-qspi
Acked-by: William Zhang <william.zhang@broadcom.com> # bcm63xx-hsspi driver
Reviewed-by: Serge Semin <fancer.lancer@gmail.com> # DW SSI part
Link: https://lore.kernel.org/r/167847070432.26.15076794204368669839@mailman-core.alsa-project.org
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230303172041.2103336-11-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Convert to use GPIO descriptors

This one is pretty straight forward to switch over, the driver
already relies on inspecting cs_gpio just check cs_gpiod instead
and stop the special handling of requesting the GPIO and stuff
the core will take care of.

Cc: Lukas Wunner <lukas@wunner.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220201012956.563272-1-linus.walleij@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: use 'unsigned int' instead of 'unsigned'

Prefer 'unsigned int' to bare use of 'unsigned'.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Link: https://lore.kernel.org/r/20210731133342.432575-1-wangborong@cdjrlc.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: delete repeated words in comments

Drop repeated words in spi-bcm2835aux.c
{are}

Drop repeated words in spi-dw-mmio.c
{the}

Drop repeated words in spi-geni-qcom.c
{our}

Drop repeated words in spi-pl022.c
{on}

Drop repeated words in spi-ppc4xx.c
{the}

Signed-off-by: Jay Fang <f.fangjian@huawei.com>
Link: https://lore.kernel.org/r/1620629903-15493-4-git-send-email-f.fangjian@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Call the dedicated transfer completion function.

spi_finalize_current_transfer currently only calls "complete", so no
functional change is expected.

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Link: https://lore.kernel.org/r/2636096a3b40febf680f9fff33944a5480561df9.1610062884.git.plr.vincent@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Restore err assignment in bcm2835aux_spi_probe

Clang warns:

drivers/spi/spi-bcm2835aux.c:532:50: warning: variable 'err' is
uninitialized when used here [-Wuninitialized]
dev_err(&pdev->dev, "could not get clk: %d\n", err);
^~~
./include/linux/dev_printk.h:112:32: note: expanded from macro 'dev_err'
_dev_err(dev, dev_fmt(fmt), ##__VA_ARGS__)
^~~~~~~~~~~
drivers/spi/spi-bcm2835aux.c:495:9: note: initialize the variable 'err'
to silence this warning
int err;
^
= 0
1 warning generated.

Restore the assignment so that the error value can be used in the
dev_err statement and there is no uninitialized memory being leaked.

Fixes: e13ee6cc4781 ("spi: bcm2835aux: Fix use-after-free on unbind")
Link: https://github.com/ClangBuiltLinux/linux/issues/1199
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20201113180701.455541-1-natechancellor@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Fix use-after-free on unbind

bcm2835aux_spi_remove() accesses the driver's private data after calling
spi_unregister_master() even though that function releases the last
reference on the spi_master and thereby frees the private data.

Fix by switching over to the new devm_spi_alloc_master() helper which
keeps the private data accessible until the driver has unbound.

Fixes: b9dd3f6d4172 ("spi: bcm2835aux: Fix controller unregister order")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v4.4+: 123456789abc: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v4.4+: b9dd3f6d4172: spi: bcm2835aux: Fix controller unregister order
Cc: <stable@vger.kernel.org> # v4.4+
Link: https://lore.kernel.org/r/b290b06357d0c0bdee9cecc539b840a90630f101.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

spi: bcm2835aux: support effective_speed_hz

Setting spi_transfer->effective_speed_hz in transfer_one so that
it can get used in cs_change_delay configured with delay as a muliple
of SPI clock cycles.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20200709074120.110069-3-mkl@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Fix controller unregister order

The BCM2835aux SPI driver uses devm_spi_register_master() on bind.
As a consequence, on unbind, __device_release_driver() first invokes
bcm2835aux_spi_remove() before unregistering the SPI controller via
devres_release_all().

This order is incorrect: bcm2835aux_spi_remove() turns off the SPI
controller, including its interrupts and clock. The SPI controller
is thus no longer usable.

When the SPI controller is subsequently unregistered, it unbinds all
its slave devices. If their drivers need to access the SPI bus,
e.g. to quiesce their interrupts, unbinding will fail.

As a rule, devm_spi_register_master() must not be used if the
->remove() hook performs teardown steps which shall be performed
after unbinding of slaves.

Fix by using the non-devm variant spi_register_master(). Note that the
struct spi_master as well as the driver-private data are not freed until
after bcm2835aux_spi_remove() has finished, so accessing them is safe.

Fixes: 1ea29b39f4c8 ("spi: bcm2835aux: add bcm2835 auxiliary spi device driver")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v4.4+
Cc: Martin Sperl <kernel@martin.sperl.org>
Link: https://lore.kernel.org/r/32f27f4d8242e4d75f9a53f7e8f1f77483b08669.1589557526.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: use devm_platform_ioremap_resource() to simplify code

Use devm_platform_ioremap_resource() to simplify the code a bit.
This is detected by coccinelle.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190904135918.25352-6-yuehaibing@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: Remove dev_err() usage after platform_get_irq()

We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.

// <smpl>
@@
expression ret;
struct platform_device *E;
@@

ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);

if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>

While we're here, remove braces on if statements that only have one
statement (manually).

Cc: Mark Brown <broonie@kernel.org>
Cc: linux-spi@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20190730181557.90391-42-swboyd@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157

Based on 3 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [kishon] [vijay] [abraham]
[i] [kishon]@[ti] [com] this program is distributed in the hope that
it will be useful but without any warranty without even the implied
warranty of merchantability or fitness for a particular purpose see
the gnu general public license for more details

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [graeme] [gregory]
[gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i]
[kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema]
[hk] [hemahk]@[ti] [com] this program is distributed in the hope
that it will be useful but without any warranty without even the
implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1105 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

spi: bcm2835aux: Remove spi_alloc_master() error printing

Printing an error on memory allocation failure is unnecessary,
as the memory allocation core code already takes care of that.

Signed-off-by: Hoan Nguyen An <na-hoan@jinso.co.jp>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Fix build error without CONFIG_DEBUG_FS

When building CONFIG_DEBUG_FS is not set
gcc warn this:

drivers/spi/spi-bcm2835aux.c: In function bcm2835aux_spi_probe:
drivers/spi/spi-bcm2835aux.c:591:2: error: too many arguments to function bcm2835aux_debugfs_create
bcm2835aux_debugfs_create(bs, dev_name(&pdev->dev));
^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/spi/spi-bcm2835aux.c:145:13: note: declared here
static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs)

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 8048d151eb4d ("spi: bcm2835aux: add driver stats to debugfs")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: polling_limit_us can be static

Fixes: 5fd917afc4bf ("spi: bcm2835aux: make the polling duration limits configurable")
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: add driver stats to debugfs

To estimate efficiency add statistics on transfer types
(polling and interrupt) used to debugfs.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: make the polling duration limits configurable

Under some circumstances the default 30 us polling limit is not optimal
and may lead to long delays because we are waiting on an interrupt.
with this patch we have the possibility to influence this policy.

So make this limit (in us) configurable via a module parameters
(but also modifyable via /sys/modules/...)

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: setup gpio-cs to output and correct level during setup

Setup gpio-cs to the correct levels during setup and also make the
gpio definitely an output GPIO.

This is transparently fixing some badly configured DTs in the process
where cs-gpio is set but the gpios are still configured with native cs.

It also makes 100% sure that the initial CS levels are as expected -
especially on systems with devices on a bus with mixed CS_HIGH/CS_LOW
settings.

Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...")
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: warn in dmesg that native cs is not really supported

From personal bad experience (even as the author of the original driver)
it shows that native-cs is "somewhat" supported by the spi bus driver
when using a buggy device tree.

So make sure that the driver is warning in dmesg about this fact
that we are running in a not supported mode that may have surprizing
limitations.

Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...")
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: fix driver to not allow 65535 (=-1) cs-gpios

The original driver by default defines num_chipselects as -1.
This actually allicates an array of 65535 entries in
of_spi_register_master.

There is a side-effect for buggy device trees that (contrary to
dt-binding documentation) have no cs-gpio defined.

This mode was never supported by the driver due to limitations
of native cs and additional code complexity and is explicitly
not stated to be implemented.

To keep backwards compatibility with such buggy DTs we limit
the number of chip_selects to 1, as for all practical purposes
it is only ever realistic to use a single chip select in
native cs mode without negative side-effects.

Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...")
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: remove dead code

Remove dead code that never can get reached, as we limit count to
a max of 3.

Suggested-by: Hubert Denkmair <h.denkmair@intence.de>
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: fix corruptions for longer spi transfers

On long running tests with a mcp2517fd can controller it showed that
on rare occations the data read shows corruptions for longer spi transfers.

Example of a 22 byte transfer:

expected (as captured on logic analyzer):
FF FF 78 00 00 00 08 06 00 00 91 20 77 56 84 85 86 87 88 89 8a 8b

read by the driver:
FF FF 78 00 00 00 08 06 00 00 91 20 77 56 84 88 89 8a 00 00 8b 9b

To fix this use BCM2835_AUX_SPI_STAT_RX_LVL to determine when we may
read data from the fifo reliably without any corruption.

Surprisingly the only values ever empirically read in
BCM2835_AUX_SPI_STAT_RX_LVL are 0x00, 0x10, 0x20 and 0x30.
So whenever the mask is not 0 we can read from the fifo in a safe manner.

The patch has now been tested intensively and we are no longer
able to reproduce the "RX" issue any longer.

Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...")
Reported-by: Hubert Denkmair <h.denkmair@intence.de>
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: remove dangerous uncontrolled read of fifo

This read of the fifo is a potential candidate for a race condition
as the spi transfer is not necessarily finished and so can lead to
an early read of the fifo that still misses data.

So it has been removed.

Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...")
Suggested-by: Hubert Denkmair <h.denkmair@intence.de>
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: unifying code between polling and interrupt driven code

Sharing more code between polling and interrupt-driven mode.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: remove unneeded NULL check of devm_clk_get

Fix a static code checker warning:
drivers/spi/spi-bcm2835aux.c:460
bcm2835aux_spi_probe() warn: passing zero to 'PTR_ERR'

In case of error, the function devm_clk_get() returns ERR_PTR()
and not returns NULL.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835: make license text and module license match

The license text is specifying GPL v2 or later but the MODULE_LICENSE
is set to GPL v2 which means GNU Public License v2 only. So choose the
license text as the correct one.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Acked-by: Florian Kauer <florian.kauer@koalo.de>
Acked-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: ensure interrupts are enabled for shared handler

The BCM2835 AUX SPI has a shared interrupt line (with AUX UART).
Downstream fixes this with an AUX irqchip to demux the IRQ sources and a
DT change which breaks compatibility with older kernels. The AUX irqchip
was already rejected for upstream[1] and the DT change would break
working systems if the DTB is updated to a newer one. The latter issue
was brought to my attention by Alex Graf.

The root cause however is a bug in the shared handler. Shared handlers
must check that interrupts are actually enabled before servicing the
interrupt. Add a check that the TXEMPTY or IDLE interrupts are enabled.

[1] https://patchwork.kernel.org/patch/9781221/

Cc: Alexander Graf <agraf@suse.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: linux-spi@vger.kernel.org
Cc: linux-rpi-kernel@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: Avoid 64-bit arithmetic in xfer len calc

We want to check for xfers that are over 30 microseconds. Rather than
find how many µs a xfer will take, instead find how many bytes can be
transferred in 30 µs. The latter must be less than 32 bits (since our
clock speed is limited to 32 bits), while the former involves 64 bit
quantities and more arithmetic operations.

Signed-off-by: Trent Piepho <tpiepho@impinj.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: fix CPOL/CPHA setting

The auxiliary spi supports only CPHA=0 modes as the first bit is
always output to the pin before the first clock cycle. In CPHA=1
modes the first clock edge outputs the second bit hence the slave
can never read the first bit.

Also the CPHA registers switch between clocking data in/out on
rising/falling edge hence depend on the CPOL setting.

Signed-off-by: Stephan Olbrich <stephanolbrich@gmx.de>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: set up spi-mode before asserting cs-gpio

When using reverse polarity for clock (spi-cpol) on a device
the clock line gets altered after chip-select has been asserted
resulting in an additional clock beat, which confuses hardware.

This happens due to the fact, the the hardware was initialized
and reset at the begin and end of each transfer which results
in default state for all lines except chip-select which is
handled by the spi-subsystem as gpio-cs is used.

To avoid this situation this patch moves the setup of polarity
(spi-cpol and spi-cpha) outside of the chip-select into
prepare_message, which is run prior to asserting chip-select.

Signed-off-by: Stephan Olbrich <stephanolbrich@gmx.de>
Reviewed-by: Martin Sperl <kernel@martin.sperl.org>
Tested-by: Martin Sperl <kernel@martin.sperl.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: disable tx fifo empty irq

The tx empty irq can be disabled when all data was copied.
This prevents unnecessary interrupts while the last bytes are sent.

Signed-off-by: Stephan Olbrich <stephanolbrich@gmx.de>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: fix bitmask defines

The bitmasks for txempty and idle interrupts were interchanged.

Signed-off-by: Stephan Olbrich <stephanolbrich@gmx.de>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: change initialization order and switch to platform_get_irq

Change the initialization order of the HW so that the interrupt
is only requested after the HW is initialized

Also the use of irq_of_parse_and_map is replaced by platform_get_irq.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: fixed bad data on longer transfers

There are strange issues with the auxiliary spi device that result
in "lost" data in the RX path if the fifo is filled by too much
(even though the status register is checked if new data can get filled
in).

This has been observed primarily for the interrupt case.
Polling works fine, probably because the RX fifo is pulled immediately
when in the tight polling loop.

For that reason we have to limit the pending bytes to less than 15
when filling the fifo in interrupt mode.

There also was an issue returning the "wrong" last 1/2 bytes
of a transfer when the transfer is not a multiple of 3 bytes.
(this impacted polling and interrupt modes)

Also fixed an overflow in the estimation of the transfer time used
to decide if we run in interrupt or polling mode (found with the
spi-bcm2835.c driver originally).

Reported-by: Georgii Staroselskii <georgii.staroselskii@emlid.com>
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

spi: bcm2835aux: add bcm2835 auxiliary spi device driver

The bcm2835 has 2 auxiliary spi bus masters spi1 and spi2.

This implements the driver to enable these devices.

The driver does not implement native chip-selects but uses
the aribtrary GPIO-chip-selects provided by the spi-chipselect.

Note that this driver relies on the fact that
the clock is implemented by the clk-bcm2835-aux driver,
which enables/disables the HW block when requesting/releasing
the clock.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>