SPI transfers were limited to one FIFO depth, which is 64 bytes.
This was an artificial limitation, however, as the hardware can handle
much larger bursts. To accommodate this, we enable the interrupt when
the Rx FIFO is 3/4 full, and drain the FIFO within the interrupt
handler. The 3/4 ratio was chosen arbitrarily, with the intention to
reduce the potential number of interrupts.
Since the SUN4I_CTL_TP bit is set, the hardware will pause
transmission whenever the FIFO is full, so there is no risk of losing
data if we can't service the interrupt in time.
For the Tx side, enable and use the Tx FIFO 3/4 empty interrupt to
replenish the FIFO on large SPI bursts. This requires more care in
when the interrupt is left enabled, as this interrupt will continually
trigger when the FIFO is less than 1/4 full, even though we
acknowledge it.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Olliver Schinagl <o.schinagl@ultimaker.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The speed limits are unset in the sun4i and sun6i SPI drivers.
The maximum speed of SPI master is used when maximum speed of SPI slave
is not specified. Also the __spi_validate function should check that
transfer speeds do not exceed the master limits.
The user manual for A10 and A31 specifies maximum
speed of the SPI clock as 100MHz and minimum as 3kHz.
Setting the SPI clock to out-of-spec values can lock up the SoC.
Signed-off-by: Michal Suchanek <hramrach@gmail.com>
--
v2:
new patch
v3:
fix constant style
Signed-off-by: Mark Brown <broonie@kernel.org>
The trasfer timeout is fixed at 1000 ms. Reading a 4Mbyte flash over
1MHz SPI bus takes way longer than that. Calculate the timeout from the
actual time the transfer is supposed to take and multiply by 2 for good
measure.
Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
When testing SPI without DMA I noticed that filling the FIFO on the
spi controller causes timeout.
Always leave room for one byte in the FIFO.
Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
The sun4i spi hardware can trasfer at most 63 bytes of data without DMA
support so report the limitation. Same for sun6i.
Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The SPI core calls set_cs before a transfer, but the SUN4I_CTL_CS_MANUAL
flag is only set in transfer_one. This leads to the following pattern on
the chip-select line (with runtime power-management on every transfer,
without it only on the first one):
activate, deactivate, activate, transfer, deactivate
Moving the configuration of the SUN4I_CTL_CS_MANUAL flag from transfer_one
to set_cs removes the double activation.
Signed-off-by: Marcus Weseloh <mweseloh42@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Allow transfers to set the transmission speed rather than using the
device max_speed_hz value. The SPI core makes sure that the speed_hz
value is always set on the transfer.
Signed-off-by: Marcus Weseloh <mweseloh42@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This controller only supports 8 bits word length.
Set bits_per_word_mask so spi core will reject transfers that attempt to use
an unsupported bits_per_word value.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
The older Allwinner SoCs (A10, A13, A10s and A20) all have the same SPI
controller.
Unfortunately, this SPI controller, even though quite similar, is significantly
different from the recently supported A31 SPI controller (different registers
offset, split/merged registers, etc.). Supporting both controllers in a single
driver would be unreasonable, hence the addition of a new driver.
Like its more recent counterpart, it supports DMA, but the driver only does PIO
until we have a dmaengine driver for this platform.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
