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path: root/drivers/spi/spi-bcm2835.c
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2021-07-20spi: spi-bcm2835: Fix deadlockAlexandru Tachici
The bcm2835_spi_transfer_one function can create a deadlock if it is called while another thread already has the CCF lock. Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com> Fixes: f8043872e796 ("spi: add driver for BCM2835") Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20210716210245.13240-2-alexandru.tachici@analog.com Signed-off-by: Mark Brown <broonie@kernel.org>
2021-06-02spi: bcm2835: Allow arbitrary number of slavesLukas Wunner
Since commit 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()"), the number of slaves has been limited by a compile-time constant. This was necessitated by statically-sized arrays in the driver private data which contain per-slave register values. As suggested by Mark, move those register values to a per-slave controller_state which is allocated on ->setup and freed on ->cleanup. The limitation on the number of slaves is thus lifted. Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Joe Burmeister <joe.burmeister@devtank.co.uk> Cc: Phil Elwell <phil@raspberrypi.com> Link: https://lore.kernel.org/r/a847c01f09400801e74e0630bf5a0197591554da.1622150204.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2021-05-24spi: bcm2835: Fix out-of-bounds access with more than 4 slavesLukas Wunner
Commit 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()") limited the number of slaves to 3 at compile-time. The limitation was necessitated by a statically-sized array prepare_cs[] in the driver private data which contains a per-slave register value. The commit sought to enforce the limitation at run-time by setting the controller's num_chipselect to 3: Slaves with a higher chipselect are rejected by spi_add_device(). However the commit neglected that num_chipselect only limits the number of *native* chipselects. If GPIO chipselects are specified in the device tree for more than 3 slaves, num_chipselect is silently raised by of_spi_get_gpio_numbers() and the result are out-of-bounds accesses to the statically-sized array prepare_cs[]. As a bandaid fix which is backportable to stable, raise the number of allowed slaves to 24 (which "ought to be enough for anybody"), enforce the limitation on slave ->setup and revert num_chipselect to 3 (which is the number of native chipselects supported by the controller). An upcoming for-next commit will allow an arbitrary number of slaves. Fixes: 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()") Reported-by: Joe Burmeister <joe.burmeister@devtank.co.uk> Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: stable@vger.kernel.org # v5.4+ Cc: Phil Elwell <phil@raspberrypi.com> Link: https://lore.kernel.org/r/75854affc1923309fde05e47494263bde73e5592.1621703210.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2021-01-14spi: bcm2835: Call the dedicated transfer completion function.Vincent Pelletier
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/633c3d5c350dde4d14ce2120c32698c25b95d302.1610062884.git.plr.vincent@gmail.com Signed-off-by: Mark Brown <broonie@kernel.org>
2021-01-13spi: bcm2835: Set controller max_speed_hzRichard Fitzgerald
Set the struct spi_controller max_speed_hz. This is based on the reported source clock frequency during probe. The maximum bus clock is half the source clock (as per the code in bcm2835_spi_transfer_one). Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Link: https://lore.kernel.org/r/20210107164825.21919-1-rf@opensource.cirrus.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-11-12spi: bcm2835: Fix use-after-free on unbindLukas Wunner
bcm2835_spi_remove() accesses the driver's private data after calling spi_unregister_controller() even though that function releases the last reference on the spi_controller 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: f8043872e796 ("spi: add driver for BCM2835") Reported-by: Sascha Hauer <s.hauer@pengutronix.de> Reported-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: <stable@vger.kernel.org> # v3.10+: 123456789abc: spi: Introduce device-managed SPI controller allocation Cc: <stable@vger.kernel.org> # v3.10+ Cc: Vladimir Oltean <olteanv@gmail.com> Tested-by: Florian Fainelli <f.fainelli@gmail.com> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/ad66e0a0ad96feb848814842ecf5b6a4539ef35c.1605121038.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2020-11-06spi: bcm2835: remove use of uninitialized gpio flags variableMartin Hundebøll
Removing the duplicate gpio chip select level handling in bcm2835_spi_setup() left the lflags variable uninitialized. Avoid trhe use of such variable by passing default flags to gpiochip_request_own_desc(). Fixes: 5e31ba0c0543 ("spi: bcm2835: fix gpio cs level inversion") Signed-off-by: Martin Hundebøll <martin@geanix.com> Link: https://lore.kernel.org/r/20201105090615.620315-1-martin@geanix.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-10-29spi: bcm2835: fix gpio cs level inversionMartin Hundebøll
The work on improving gpio chip-select in spi core, and the following fixes, has caused the bcm2835 spi driver to use wrong levels. Fix this by simply removing level handling in the bcm2835 driver, and let the core do its work. Fixes: 3e5ec1db8bfe ("spi: Fix SPI_CS_HIGH setting when using native and GPIO CS") Cc: <stable@vger.kernel.org> Signed-off-by: Martin Hundebøll <martin@geanix.com> Link: https://lore.kernel.org/r/20201014090230.2706810-1-martin@geanix.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-09-14spi: bcm2835: Make polling_limit_us staticJason Yan
This eliminates the following sparse warning: drivers/spi/spi-bcm2835.c:78:14: warning: symbol 'polling_limit_us' was not declared. Should it be static? Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Jason Yan <yanaijie@huawei.com> Link: https://lore.kernel.org/r/20200912072211.602735-1-yanaijie@huawei.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-09-08spi: bcm2835: Simplify with dev_err_probe()Krzysztof Kozlowski
Common pattern of handling deferred probe can be simplified with dev_err_probe(). Less code and the error value gets printed. Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20200901152713.18629-4-krzk@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2020-07-17spi: bcm2835: support effective_speed_hzMartin Sperl
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/20200709074120.110069-2-mkl@pengutronix.de Signed-off-by: Mark Brown <broonie@kernel.org>
2020-07-01spi: bcm2835: Micro-optimise FIFO loopsRobin Murphy
The blind and counted loops are always called with nonzero count, so convert them to do-while loops that lead to slightly more efficient code generation. With GCC 8.3 this shaves off 1-2 instructions per iteration in each case. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/9242863077acf9a64e4b3720e479855b88d19e82.1592261248.git.robin.murphy@arm.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-07-01spi: bcm2835: Micro-optimise IRQ handlerRobin Murphy
The IRQ handler only needs the struct spi_controller for the sake of the completion at the end of a transfer. Passing the struct bcm2835_spi directly as the IRQ data allows that level of indirection to be pushed into the completion path for the reverse lookup, and avoided entirely in all other cases. This saves one explicit load in the critical path, plus (for a GCC 8.3 build) two registers worth of stack frame overhead. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/6b401cb521539caffab21f05b4c8cba6c9d27c6e.1592261248.git.robin.murphy@arm.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-07-01spi: bcm3835: Tidy up bcm2835_spi_reset_hw()Robin Murphy
It doesn't need a struct spi_controller, and every callsite has already retrieved the appropriate struct bcm2835_spi, so just pass that directly. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/eca458ae1a0d3934d0627f90e25d294fefd4b13d.1592261248.git.robin.murphy@arm.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-29spi: bcm2835: Remove shared interrupt supportMark Brown
This reverts commit ecfbd3cf3b8b since Lukas Wunner noticed that we start operating on the hardware before we check to see if this is a spurious interrupt. Reported-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-29spi: bcm2835: Enable shared interrupt supportMartin Sperl
bcm2711, Rasberry Pi 4's SoC, shares one interrupt for multiple instances of the bcm2835 SPI controller. So this enables shared interrupt support for them. The early bail out in the interrupt routine avoids messing with buffers of transfers being done by other means. Otherwise, the driver can handle receiving interrupts asserted by other controllers during an IRQ based transfer. Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Tested-by: Florian Fainelli <f.fainelli@gmail.com> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20200528185805.28991-1-nsaenzjulienne@suse.de Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-29spi: bcm2835: Implement shutdown callbackFlorian Fainelli
Make sure we clear the FIFOs, stop the block, disable the clock and release the DMA channel. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20200528190605.24850-1-f.fainelli@gmail.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-20spi: bcm2835: Tear down DMA before turning off SPI controllerLukas Wunner
On unbind of the BCM2835 SPI driver, the SPI controller is disabled first and the DMA channels are terminated and torn down afterwards. This seems backwards: In the theoretical case that DMA is active, it might try to fill the SPI FIFOs even after the controller has been disabled. Reverse the order, thereby mirroring what's done on ->probe(). Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/ac79f1e3d6fd9a1f5e0cb4008c43b98ea70be3c2.1589557526.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-20Merge branch 'for-5.7' of ↵Mark Brown
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi into spi-5.8
2020-05-20spi: bcm2835: Fix controller unregister orderLukas Wunner
The BCM2835 SPI driver uses devm_spi_register_controller() on bind. As a consequence, on unbind, __device_release_driver() first invokes bcm2835_spi_remove() before unregistering the SPI controller via devres_release_all(). This order is incorrect: bcm2835_spi_remove() tears down the DMA channels and 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_controller() 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_controller(). Note that the struct spi_controller as well as the driver-private data are not freed until after bcm2835_spi_remove() has finished, so accessing them is safe. Fixes: 247263dba208 ("spi: bcm2835: use devm_spi_register_master()") Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: stable@vger.kernel.org # v3.13+ Link: https://lore.kernel.org/r/2397dd70cdbe95e0bc4da2b9fca0f31cb94e5aed.1589557526.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-06spi: bcm2835: Fix error return code in bcm2835_dma_init()Wei Yongjun
Fix to return negative error code -ENOMEM from the dma mapping error handling case instead of 0, as done elsewhere in this function. Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Link: https://lore.kernel.org/r/20200506125607.90952-1-weiyongjun1@huawei.com Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-05spi: bcm2835: Fixes bare use of unsignedJacko Dirks
Signed-off-by: Jacko Dirks <jdirks.linuxdev@gmail.com> Link: https://lore.kernel.org/r/20200503200033.GA3256@vasteMachine Signed-off-by: Mark Brown <broonie@kernel.org>
2020-01-09spi: bcm2835: Raise maximum number of slaves to 4Lukas Wunner
The "RevPi Connect Flat" PLC offered by KUNBUS has 4 slaves attached to the BCM2835 SPI master. Raise the maximum number of slaves in the driver accordingly. Signed-off-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Link: https://lore.kernel.org/r/01453fd062de2d49bd74a847e13a0781cbf8143d.1578572268.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-12-17spi: bcm2835: no dev_err() on clk_get() -EPROBE_DEFERJim Quinlan
Use dev_dbg() on -EPROBE_DEFER and dev_err() on all other errors. Signed-off-by: Jim Quinlan <jquinlan@broadcom.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Link: https://lore.kernel.org/r/20191216230802.45715-2-jquinlan@broadcom.com Signed-off-by: Mark Brown <broonie@kernel.org>
2019-12-16spi: bcm2835: Use dma_request_chan() instead dma_request_slave_channel()Peter Ujfalusi
dma_request_slave_channel() is a wrapper on top of dma_request_chan() eating up the error code. By using dma_request_chan() directly the driver can support deferred probing against DMA. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Link: https://lore.kernel.org/r/20191212135550.4634-4-peter.ujfalusi@ti.com Signed-off-by: Mark Brown <broonie@kernel.org>
2019-12-16spi: bcm2835: Release the DMA channel if probe fails after dma_initPeter Ujfalusi
The DMA channel was not released if either devm_request_irq() or devm_spi_register_controller() failed. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Link: https://lore.kernel.org/r/20191212135550.4634-3-peter.ujfalusi@ti.com Signed-off-by: Mark Brown <broonie@kernel.org>
2019-11-05spi: bcm2835: fix typo in commentChris Packham
GPIOS_OUT_LOW should be GPIOD_OUT_LOW. Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Link: https://lore.kernel.org/r/20191105214134.25142-1-chris.packham@alliedtelesis.co.nz Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-15Merge branch 'spi-5.4' into spi-nextMark Brown
2019-09-11spi: bcm2835: Speed up RX-only DMA transfers by zero-filling TX FIFOLukas Wunner
The BCM2835 SPI driver currently sets the SPI_CONTROLLER_MUST_TX flag. When performing an RX-only transfer, this flag causes the SPI core to allocate and DMA-map a dummy buffer which is copied to the TX FIFO. The dummy buffer is necessary because the chip is not capable of automatically clocking out null bytes. Avoid the overhead induced by the dummy buffer by preallocating a reusable DMA transaction which fills the TX FIFO by cyclically copying from the zero page. The transaction requires very little CPU time to submit and generates no interrupts while running. Specifics are provided in kerneldoc comments. [Nathan Chancellor contributed a DMA mapping fixup for an early version of this commit, hence his Signed-off-by.] Tested-by: Nuno Sá <nuno.sa@analog.com> Tested-by: Noralf Trønnes <noralf@tronnes.org> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Stefan Wahren <wahrenst@gmx.net> Acked-by: Martin Sperl <kernel@martin.sperl.org> Cc: Robert Jarzmik <robert.jarzmik@free.fr> Link: https://lore.kernel.org/r/f45920af18dbf06e34129bbc406f53dc9c5d1075.1568187525.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-11spi: bcm2835: Speed up TX-only DMA transfers by clearing RX FIFOLukas Wunner
The BCM2835 SPI driver currently sets the SPI_CONTROLLER_MUST_RX flag. When performing a TX-only transfer, this flag causes the SPI core to allocate and DMA-map a dummy buffer into which the RX FIFO contents are copied. The dummy buffer is necessary because the chip is not capable of disabling the receiver or automatically throwing away received data. Not reading the RX FIFO isn't an option either since transmission is halted once it's full. Avoid the overhead induced by the dummy buffer by preallocating a reusable DMA transaction which cyclically clears the RX FIFO. The transaction requires very little CPU time to submit and generates no interrupts while running. Specifics are provided in kerneldoc comments. With a ks8851 Ethernet chip attached to the SPI controller, I am seeing a 30 us reduction in ping time with this commit (1.819 ms vs. 1.849 ms, average of 100,000 packets) as well as a 2% reduction in CPU time (75:08 vs. 76:39 for transmission of 5 GByte over the SPI bus). The commit uses the TX DMA interrupt to signal completion of a transfer. This interrupt is raised once all bytes have been written to the TX FIFO and it is then necessary to busy-wait for the TX FIFO to become empty before the transfer can be finalized. As an alternative approach, I have explored using the SPI controller's DONE interrupt to detect completion. This interrupt is signaled when the TX FIFO becomes empty, avoiding the need to busy-wait. However latency deteriorates compared to the present commit and surprisingly, CPU time is slightly higher as well: It turns out that in 45% of the cases, no busy-waiting is needed at all and in 76% of the cases, less than 10 busy-wait iterations are sufficient for the TX FIFO to drain. This was measured on an RT kernel. On a vanilla kernel, wakeup latency is worse and thus fewer iterations are needed. The measurements were made with an SPI clock of 20 MHz, they may differ slightly for slower or faster clock speeds. Previously we always used the RX DMA interrupt to signal completion of a transfer. Using the TX DMA interrupt now introduces a race condition: TX DMA is always started before RX DMA so that bytes are already clocked out while RX DMA is still being set up. But if a TX-only transfer is very short, then the TX DMA interrupt may occur before RX DMA is set up. If the interrupt happens to occur on the same CPU, setup of RX DMA may even be delayed until after the interrupt was handled. I've solved this by having the TX DMA callback clear the RX FIFO while busy-waiting for the TX FIFO to drain, thus avoiding a dependency on setup of RX DMA. Additionally, I am using a lock-free mechanism with two flags, tx_dma_active and rx_dma_active plus memory barriers to terminate RX DMA either by the TX DMA callback or immediately after setting it up, whichever wins the race. I've explored an alternative approach which temporarily disables the TX DMA callback until RX DMA has been set up (using tasklet_disable(), local_bh_disable() or local_irq_save()), but the performance was minimally worse. [Nathan Chancellor contributed a DMA mapping fixup for an early version of this commit, hence his Signed-off-by.] Tested-by: Nuno Sá <nuno.sa@analog.com> Tested-by: Noralf Trønnes <noralf@tronnes.org> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Stefan Wahren <wahrenst@gmx.net> Acked-by: Martin Sperl <kernel@martin.sperl.org> Cc: Robert Jarzmik <robert.jarzmik@free.fr> Link: https://lore.kernel.org/r/874949385f28251e2dcaa9494e39a27b50e9f9e4.1568187525.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-11spi: bcm2835: Cache CS register value for ->prepare_message()Lukas Wunner
The BCM2835 SPI driver needs to set up the clock polarity in its ->prepare_message() hook before spi_transfer_one_message() asserts chip select to avoid a gratuitous clock signal edge (cf. commit acace73df2c1 ("spi: bcm2835: set up spi-mode before asserting cs-gpio")). Precalculate the CS register value (which selects the clock polarity) once in ->setup() and use that cached value in ->prepare_message() and ->transfer_one(). This avoids one MMIO read per message and one per transfer, yielding a small latency improvement. Additionally, a forthcoming commit will use the precalculated value to derive the register value for clearing the RX FIFO, which will eliminate the need for an RX dummy buffer when performing TX-only DMA transfers. Tested-by: Nuno Sá <nuno.sa@analog.com> Tested-by: Noralf Trønnes <noralf@tronnes.org> Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Stefan Wahren <wahrenst@gmx.net> Acked-by: Martin Sperl <kernel@martin.sperl.org> Link: https://lore.kernel.org/r/d17c1d7fcdc97fffa961b8737cfd80eeb14f9416.1568187525.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-11spi: bcm2835: Drop dma_pending flagLukas Wunner
The BCM2835 SPI driver uses a flag to keep track of whether a DMA transfer is in progress. The flag is used to avoid terminating DMA channels multiple times if a transfer finishes orderly while simultaneously the SPI core invokes the ->handle_err() callback because the transfer took too long. However terminating DMA channels multiple times is perfectly fine, so the flag is unnecessary for this particular purpose. The flag is also used to avoid invoking bcm2835_spi_undo_prologue() multiple times under this race condition. However multiple *concurrent* invocations can no longer happen since commit 2527704d8411 ("spi: bcm2835: Synchronize with callback on DMA termination") because the ->handle_err() callback now uses the _sync() variant when terminating DMA channels. The only raison d'être of the flag is therefore that bcm2835_spi_undo_prologue() cannot cope with multiple *sequential* invocations. Achieve that by setting tx_prologue to 0 at the end of the function. Subsequent invocations thus become no-ops. With that, the dma_pending flag becomes unnecessary, so drop it. Tested-by: Nuno Sá <nuno.sa@analog.com> Tested-by: Noralf Trønnes <noralf@tronnes.org> Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Stefan Wahren <wahrenst@gmx.net> Acked-by: Martin Sperl <kernel@martin.sperl.org> Link: https://lore.kernel.org/r/062b03b7f86af77a13ce0ec3b22e0bdbfcfba10d.1568187525.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-10spi: bcm2835: Work around DONE bit erratumLukas Wunner
Commit 3bd7f6589f67 ("spi: bcm2835: Overcome sglist entry length limitation") amended the BCM2835 SPI driver with support for DMA transfers whose buffers are not aligned to 4 bytes and require more than one sglist entry. When testing this feature with upcoming commits to speed up TX-only and RX-only transfers, I noticed that SPI transmission sometimes breaks. A function introduced by the commit, bcm2835_spi_transfer_prologue(), performs one or two PIO transmissions as a prologue to the actual DMA transmission. It turns out that the breakage goes away if the DONE bit in the CS register is set when ending such a PIO transmission. The DONE bit signifies emptiness of the TX FIFO. According to the spec, the bit is of type RO, so writing it should never have any effect. Perhaps the spec is wrong and the bit is actually of type RW1C. E.g. the I2C controller on the BCM2835 does have an RW1C DONE bit which needs to be cleared by the driver. Another, possibly more likely explanation is that it's a hardware erratum since the issue does not occur consistently. Either way, amend bcm2835_spi_transfer_prologue() to always write the DONE bit. Usually a transmission is ended by bcm2835_spi_reset_hw(). If the transmission was successful, the TX FIFO is empty and thus the DONE bit is set when bcm2835_spi_reset_hw() reads the CS register. The bit is then written back to the register, so we happen to do the right thing. However if DONE is not set, e.g. because transmission is aborted with a non-empty TX FIFO, the bit won't be written by bcm2835_spi_reset_hw() and it seems possible that transmission might subsequently break. To be on the safe side, likewise amend bcm2835_spi_reset_hw() to always write the bit. Tested-by: Nuno Sá <nuno.sa@analog.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Stefan Wahren <wahrenst@gmx.net> Acked-by: Martin Sperl <kernel@martin.sperl.org> Link: https://lore.kernel.org/r/edb004dff4af6106f6bfcb89e1a96391e96eb857.1564825752.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-04spi: bcm2835: use devm_platform_ioremap_resource() to simplify codeYueHaibing
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/20190904135918.25352-7-yuehaibing@huawei.com Signed-off-by: Mark Brown <broonie@kernel.org>
2019-08-28spi: bcm2835: Convert to use CS GPIO descriptorsLinus Walleij
This converts the BCM2835 SPI master driver to use GPIO descriptors for chip select handling. The BCM2835 driver was relying on the core to drive the CS high/low so very small changes were needed for this part. If it managed to request the CS from the device tree node, all is pretty straight forward. However for native GPIOs this driver has a quite unorthodox loopback to request some GPIOs from the SoC GPIO chip by looking it up from the device tree using gpiochip_find() and then offseting hard into its numberspace. This has been augmented a bit by using gpiochip_request_own_desc() but this code really needs to be verified. If "native CS" is actually an SoC GPIO, why is it even done this way? Should this GPIO not just be defined in the device tree like any other CS GPIO? I'm confused. Cc: Lukas Wunner <lukas@wunner.de> Cc: Stefan Wahren <stefan.wahren@i2se.com> Cc: Martin Sperl <kernel@martin.sperl.org> Cc: Chris Boot <bootc@bootc.net> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Link: https://lore.kernel.org/r/20190804003852.1312-1-linus.walleij@linaro.org Signed-off-by: Mark Brown <broonie@kernel.org>
2019-08-23Merge branch 'spi-5.3' into spi-5.4Mark Brown
2019-08-02spi: Remove dev_err() usage after platform_get_irq()Stephen Boyd
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>
2019-07-24spi: bcm2835: Fix 3-wire mode if DMA is enabledLukas Wunner
Commit 6935224da248 ("spi: bcm2835: enable support of 3-wire mode") added 3-wire support to the BCM2835 SPI driver by setting the REN bit (Read Enable) in the CS register when receiving data. The REN bit puts the transmitter in high-impedance state. The driver recognizes that data is to be received by checking whether the rx_buf of a transfer is non-NULL. Commit 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers meeting certain conditions") subsequently broke 3-wire support because it set the SPI_MASTER_MUST_RX flag which causes spi_map_msg() to replace rx_buf with a dummy buffer if it is NULL. As a result, rx_buf is *always* non-NULL if DMA is enabled. Reinstate 3-wire support by not only checking whether rx_buf is non-NULL, but also checking that it is not the dummy buffer. Fixes: 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers meeting certain conditions") Reported-by: Nuno Sá <nuno.sa@analog.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: stable@vger.kernel.org # v4.2+ Cc: Martin Sperl <kernel@martin.sperl.org> Acked-by: Stefan Wahren <wahrenst@gmx.net> Link: https://lore.kernel.org/r/328318841455e505370ef8ecad97b646c033dc8a.1562148527.git.lukas@wunner.de Signed-off-by: Mark Brown <broonie@kernel.org>
2019-06-10Merge tag 'v5.2-rc4' into spi-5.3Mark Brown
Linux 5.2-rc4
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157Thomas Gleixner
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>
2019-05-22spi: bcm2835: Drop assignment of dma_slave_config directionLukas Wunner
The BCM2835 SPI driver still sets the "direction" member in struct dma_slave_config even though it was deprecated five years ago with commit d9ff958bb34a ("dmaengine: Mark the struct dma_slave_config direction field deprecated") and is no longer evaluated by the BCM2835 DMA driver since commit 00648f4d0f41 ("dmaengine: bcm2835: remove dma_slave_config direction usage"). Drop the superfluous assignment. No functional change intended. Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Frank Pavlic <f.pavlic@kunbus.de> Cc: Martin Sperl <kernel@martin.sperl.org> Cc: Noralf Trønnes <noralf@tronnes.org> Reviewed-by: Vinod Koul <vkoul@kernel.org> Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-22spi: bcm2835: Replace spi_master by spi_controllerLukas Wunner
Commit 8caab75fd2c2 ('spi: Generalize SPI "master" to "controller"') changed the "spi_master" nomenclature to "spi_controller", necessitating a conversion of all drivers. Perform this conversion for the BCM2835 SPI driver. No functional change intended. Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Frank Pavlic <f.pavlic@kunbus.de> Cc: Martin Sperl <kernel@martin.sperl.org> Cc: Noralf Trønnes <noralf@tronnes.org> Cc: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-13spi: bcm2835: only split transfers that exceed DLEN if DMA availableNicolas Saenz Julienne
There is no use for this when performing non DMA operations. So we bypass the split. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-13spi: bcm2835: Remove spi_alloc_master() error printingHoan Nguyen An
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>
2019-05-08spi: bcm2835: add driver stats to debugfsMartin Sperl
To estimate efficiency add statistics on transfer types (polling, interrupt and dma) used to debugfs. Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Changelog: V1 -> V2: applied feedback by Stefan Wahren reorganized patchset added extra rational, descriptions fixed compile issue when CONFIG_DEBUG_FS is unset Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-08spi: bcm2835: make the polling duration limits configurableMartin Sperl
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/...) This replicates similar code found in spi-bcm2835aux. Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Changelog: V1 -> V2: applied feedback by Stefan Wahren reorganized patchset added extra rational, descriptions Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-08spi: bcm2835: added comment about different bus behaviour of DMA modeMartin Sperl
The DMA mode behaves slightly different than polling or interrupt driven mode, so just document the fact Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Changelog: V1 -> V2: applied feedback by Stefan Wahren new in V2 Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-08spi: bcm2835: Avoid 64-bit arithmetic in xfer len calcMartin Sperl
Avoid 64 bit aritmetics when deciding if we need to use polling or not This replicates: commit d704afffe65c ("spi: bcm2835aux: Avoid 64-bit arithmetic in xfer len calc") from spi-bcm2835aux Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Changelog: V1 -> V2: applied feedback by Stefan Wahren reorganized patchset added extra rational, descriptions Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-08spi: bcm2835: bcm2835_spi_transfer_one_poll remove unnecessary argumentMartin Sperl
Remove the unnecessary argument of xfer_time_us when calling bcm2835_spi_transfer_one_poll. Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Changelog: V1 -> V2: applied feedback by Stefan Wahren reorganized patchset added extra rational, descriptions Signed-off-by: Mark Brown <broonie@kernel.org>
2019-05-02spi/spi-bcm2835: Split transfers that exceed DLENMeghana Madhyastha
Split spi transfers into chunks of <=65532 to enable the driver to perform DMA transfer on big buffers. The DLEN register specifies the number of bytes to transfer in DMA mode. It is 16-bit wide and thus the maximum DMA transfer is 65535 bytes. Set the maximum to 65532 (4 byte aligned) since the FIFO in DMA mode is accessed in 4 byte chunks. ->max_dma_len is the value the spi core uses when splitting the buffer into scatter gather entries. The BCM2835 DMA block has 2 types of channels/engines: - Normal: Max length: 1G - Lite: Max length: 65535 Even when using a Lite channel we will not exceed the max length, so let's drop setting ->max_dma_len. Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com> Signed-off-by: Noralf Trønnes <noralf@tronnes.org> Reviewed-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Mark Brown <broonie@kernel.org>
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