This patch replaced "n" by "len" bytes of data in qspi_transfer_in() and
qspi_transfer_out() function. This will make improving readability.
Signed-off-by: DongCV <cv-dong@jinso.co.jp>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

In qspi_transfer_in(), when receiving the last n (or len) bytes of data,
one bogus byte was written in the receive buffer.
This code leads to a buffer overflow.

"jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found
at 0x03b40000: 0x1900 instead
jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found
at 0x03b40004: 0x000c instead"

The error message above happens when trying to mount, unmount,
and remount a jffs2-formatted device.
This patch removed the bogus write to fixes: 3be09bec
"spi: rspi: supports 32bytes buffer for DUAL and QUAD"

And here is Geert's comment:

"spi: rspi: Fix bogus received byte in qspi_transfer_in()
When there are less than QSPI_BUFFER_SIZE remaining bytes to be received,
qspi_transfer_in() writes one bogus byte in the receive buffer, possibly
leading to a buffer overflow.
This can be reproduced by mounting, unmounting, and remounting a
jffs2-formatted device, causing lots of warnings like:

"jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found
at 0x03b40000: 0x1900 instead"

Remove the bogus write to fix this. "
Signed-off-by: DongCV <cv-dong@jinso.co.jp>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

Printing an error on memory allocation failure is unnecessary.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

The newly introduced rspi_pio_transfer_in_or_our() function must
take either a valid 'rx' or 'tx' pointer, and has undefined behavior
if both are NULL, as found by 'gcc -Wmaybe-unintialized':

drivers/spi/spi-rspi.c: In function 'rspi_pio_transfer_in_or_our':
drivers/spi/spi-rspi.c:558:5: error: 'len' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The analysis of the function is correct in principle, but the code
is currently safe because both callers always pass exactly one
of the two pointers.

Looking closer at this function shows that having a combined
method for rx and tx here actually increases the complexity
and the size of the file. This simplifies it again by keeping
the two separate, which then ends up avoiding that warning.

Fixes: 3be09bec ("spi: rspi: supports 32bytes buffer for DUAL and QUAD")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

This patch supports 32bytes of buffer for DUAL and QUAD in QSPI by
Using Transmit/Receive Buffer Data Triggering Number.
In order to improve the DUAL and QUAD's performance of SPI
while transferring data in PIO mode, it sends/receives each 32bytes
data instead of each byte data as current situation.
Signed-off-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Signed-off-by: Mark Brown <broonie@kernel.org>

When you leave the clock divider at 0, 130kHz is the lowest you can go.
Also, by adjusting the clock divider you can get more accurate resolutions
for clock speeds lower than 16MHz. This patch uses the clock divider as
part of the bit rate setup.
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

qspi_set_send_trigger() returns an unsigned value, so make it return
"unsigned int".
Update the loop variables qspi_trigger_transfer_out_int() to match the
above.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

Just use "ret" instead, for consistency with other similar functions.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

To reduce complexity of code, drop "ret" then qspi_transfer_out_in function
should return the value of "qspi_trigger_transfer_out_in" directly.
Signed-off-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

The name of "qspi_trigger_transfer_out_int" function should be
"qspi_trigger_transfer_out_in" without "t".
Signed-off-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

To reduce indentation and complexity of code, insteeds of returning zero
the function rspi_dma_check_then_transfer should return rspi_dma_transfer
directly after checking error.
Signed-off-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Signed-off-by: Mark Brown <broonie@kernel.org>

The platform_device_id is not modified by the driver and core uses it as
const.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

We need "ret" to be unsigned for the error handling to work.  The
signedness of "i" and "n" don't matter but qspi_set_send_trigger()
returns an int so I've changed them to int as well.

Fixes: 4b6fe3ed ('spi: Using Trigger number to transmit/receive data')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

In order to transmit and receive data when have 32 bytes of data that
ready has prepared on Transmit/Receive Buffer to transmit or receive.
Instead transmits/receives a byte data using Transmit/Receive Buffer
Data Triggering Number will improve the speed of transfer data.
Signed-off-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Signed-off-by: Mark Brown <broonie@kernel.org>

Current rspi sets dma_slave_config :: slave_id field for DMAEngine,
but it is no longer needed. Let's remove it.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

A platform_driver does not need to set an owner, it will be populated by the
driver core.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Add support for QSPI in:
  - r8a7792 (R-Car V2H)
  - r8a7793 (R-Car M2-N)
  - r8a7794 (R-Car E2)

r8a7791 is now called "R-Car M2-W".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

The new Renesas R-Car Gen2 DMA Controller driver (rcar-dmac) requires
explicit configuration of the DMA slave bus width.
Hardcode the DMA transfer size to 1 byte for both directions, as that's
the only supported configuration (16-bit DMA support was removed in
commit 9c5de2c1 ("spi: rspi: Remove
unused 16-bit DMA support")).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Use the devm_kasprintf() helper function instead of open coding
error-prone buffer handling and string formatting.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Introduced by commit 426ef76d ("spi:
rspi: Add DT support").
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

If dmaengine_prep_slave_sg() or dmaengine_submit() fail, we may leak
unused DMA descriptors.

As per Documentation/dmaengine.txt, once a DMA descriptor has been
obtained, it must be submitted. Hence:
  - First prepare and submit all DMA descriptors,
  - Prepare the SPI controller for DMA,
  - Start DMA by calling dma_async_issue_pending(),
  - Make sure to call dmaengine_terminate_all() on all descriptors that
    haven't completed.
Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

As typically a shmobile SoC has less DMA channels than devices that can use
DMA, we may want to prioritize access to the DMA channels in the future.
This means that dmaengine_prep_slave_sg() may start failing arbitrarily.

Handle dmaengine_prep_slave_sg() failures gracefully by falling back to
PIO.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

rspi_release_dma() doesn't need access to any fields in the driver private
data, except for the pointer to the SPI master object. Hence just pass the
needed pointer.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Introduced by commit 8b983e90 ("spi: rspi:
Extract rspi_common_transfer()"), which removed its users.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Extract the common parts of rspi_transfer_one(), rspi_rz_transfer_one(),
and qspi_transfer_out_in() into the new function rspi_common_transfer().
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Enable DMA support for RSPI on r7s72100 (RZ/A1H).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Enable DMA support for QSPI on R-Car Gen2, for Single, Dual, and Quad SPI
Transfers.

Performance figures for reading from a QSPI FLASH driven at 24.375 MHz
on r8a7791/koelsch:
  - Single:  1.1 Mbps PIO, 23 Mbps DMA
  - Dual  : 12.7 Mbps PIO, 48 Mbps DMA
  - Quad  : 13   Mbps PIO, 70 Mbps DMA
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

rspi_send_dma() and rspi_send_receive_dma() are very similar. Consolidate
into a single function rspi_dma_transfer(), and add missing checks for
dmaengine_submit() failures.

Both sg_table pointer parameters can be NULL, as RSPI supports TX-only
mode, and unidirectional DMA transfers will also be needed later for
Dual/Quad DMA support.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

The DMA routines only need access to the scatter-gather tables inside the
spi_transfer structures, hence just pass those.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Refactor RSPI (on SH) DMA handling to make it reusable for other RSPI
implementations:
  - Call the DMA routines after configuring the TX Mode bit and after
    calling rspi_receive_init(), so these RSPI-specific operations can be
    removed from the DMA routines,
  - Absorb rspi_transfer_out_in() into rspi_transfer_one().
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Use the SPI core DMA mapping framework instead of our own.
If available, DMA is used for transfers larger than the FIFO size
(8 or 32 bytes).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

The SPI DMA core framework needs both RX and TX DMA to function.  As a
preparation for converting the driver to use this framework, fall back to
PIO if no DMA channel or only one DMA channel is available.

This affects only RSPI, which could do DMA transfers for TX-only before.
RSPI-RZ and QSPI (at least for Single SPI Transfers) will need both RX and
TX DMA anyway.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

The resource is know to exist, as rspi_probe() already mapped it.
Remove the test, and just pass the resource.
Pass the device pointer instead of the platform device pointer, as the
latter is no longer needed.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Setup of the receive and transmit DMA channels is very similar, so let's
consolidate.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

Fall back to PIO if DMA configuration failed.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

The various PIO loops are very similar. Consolidate into a single
function rspi_pio_transfer().

Both buffer pointers can be NULL, as RSPI supports TX-only mode, and
Dual/Quad SPI Transfers are unidirectional.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

RSPI needs dummy transfers to generate the SPI clock on receive.
RSPI-RZ and QSPI always do both transmit and receive.

Use the SPI core SPI_MASTER_MUST_RX/SPI_MASTER_MUST_TX infrastructure
instead of checking for the presence of buffers and providing dummy data
ourselves (for PIO), or providing a dummy buffer (for DMA).

rspi_receive_dma() now provides full duplex DMA transfers on RSPI, and is
renamed to rspi_send_receive_dma().

As the SPI core will always provide a TX buffer, the logic to choose
between DMA send and DMA send/receive in rspi_transfer_one() now has to
check for the presence of an RX buffer. Likewise for the DMA availability
tests in rspi_is_dma().

The buffer tests in qspi_transfer_one() are now always true, so they're
removed.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>