mmc: alcor: 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.

Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Link: https://lore.kernel.org/r/20230727070051.17778-40-frank.li@vivo.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: fix return value check of mmc_add_host()

mmc_add_host() may return error, if we ignore its return value, the memory
that allocated in mmc_alloc_host() will be leaked and it will lead a kernel
crash because of deleting not added device in the remove path.

So fix this by checking the return value and calling mmc_free_host() in the
error path.

Fixes: c5413ad815a6 ("mmc: add new Alcor Micro Cardreader SD/MMC driver")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221101063023.1664968-2-yangyingliang@huawei.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in v5.4

This is like commit 3d3451124f3d ("mmc: sdhci-msm: Prefer asynchronous
probe") but applied to a whole pile of drivers. This batch converts
the drivers that appeared to be around in the v5.4 timeframe.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200903162412.5.I2b630c4d40ff4ea61d5b30b8ccfe95890e257100@changeid
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: Fix a resource leak in the error path for ->probe()

If devm_request_threaded_irq() fails, the allocated struct mmc_host needs
to be freed via calling mmc_free_host(), so let's do that.

Fixes: c5413ad815a6 ("mmc: add new Alcor Micro Cardreader SD/MMC driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20200426202355.43055-1-christophe.jaillet@wanadoo.fr
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: remove a redundant greater or equal to zero comparison

A greater or equal comparison on the unsigned int variable tmp_diff
is always true as unsigned ints are never negative. Hence the
comparison is redundant and can be removed.

Addresses-Coverity: ("Unsigned compared against 0")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: Drop pointer to mmc_host from alcor_sdmmc_host

The driver for Alcor Micro AU6601 and AU6621 controllers uses a pointer to
get from the private alcor_sdmmc_host structure to the generic mmc_host
structure. However the latter is always immediately preceding the former in
memory, so compute its address with a subtraction (which is cheaper than a
dereference) and drop the superfluous pointer.

No functional change intended.

Signed-off-by: Kamlesh Gurudasani <kamlesh.gurudasani@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: work with multiple-entry sglists

DMA on this hardware is limited to dealing with a 4096 bytes at a
time. Previously, the driver was set up accordingly to request single-page
DMA buffers, however that had the effect of generating a large number
of small MMC requests for data I/O.

Improve the driver to accept multi-entry scatter-gather lists. The size of
each entry is already capped to 4096 bytes (AU6601_MAX_DMA_BLOCK_SIZE),
matching the hardware requirements. Existing driver code already iterates
through remaining sglist entries after each DMA transfer is complete.

Also add some comments to help clarify the situation, and clear up
some of the confusion I had regarding DMA vs PIO.

Testing with dd, this increases write performance from 2mb/sec to
10mb/sec, and increases read performance from 4mb/sec to 14mb/sec.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Link: http://lkml.kernel.org/r/CAD8Lp47JYdZzbV9F+asNwvSfLF_po_J7ir6R_Vb-Dab21_=Krw@mail.gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Revert "mmc: alcor: enable DMA transfer of large buffers"

This reverts commit 57ebb96c293da9f0ec56aba13c5541269a5c10b1.

Usage of the DMA page iterator was problematic here because
we were not considering offset & length of entries in the scatterlist.

Also, after further discussion, the suggested revised approach is much
more similar to the driver implementation before this commit was
applied, so revert it.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: enable DMA transfer of large buffers

DMA on this hardware is limited to dealing with a single page at a
time. Previously, the driver was set up accordingly to request single-page
DMA buffers, however that had the effect of generating a large number
of small MMC requests for data I/O.

Improve the driver to accept scatter-gather DMA buffers of larger sizes.
Iterate through those buffers a page at a time.

Testing with dd, this increases write performance from 2mb/sec to
10mb/sec, and increases read performance from 4mb/sec to 14mb/sec.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: enable DMA for writes

Enable the DMA codepath for writes as well as reads.
This improves write speed from 1mb/sec to 2mb/sec (tested with dd).

The original ampe_stor vendor driver also uses DMA for writes.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers: Remove explicit invocations of mmiowb()

mmiowb() is now implied by spin_unlock() on architectures that require
it, so there is no reason to call it from driver code. This patch was
generated using coccinelle:

@mmiowb@
@@
- mmiowb();

and invoked as:

$ for d in drivers include/linux/qed sound; do \
spatch --include-headers --sp-file mmiowb.cocci --dir $d --in-place; done

NOTE: mmiowb() has only ever guaranteed ordering in conjunction with
spin_unlock(). However, pairing each mmiowb() removal in this patch with
the corresponding call to spin_unlock() is not at all trivial, so there
is a small chance that this change may regress any drivers incorrectly
relying on mmiowb() to order MMIO writes between CPUs using lock-free
synchronisation. If you've ended up bisecting to this commit, you can
reintroduce the mmiowb() calls using wmb() instead, which should restore
the old behaviour on all architectures other than some esoteric ia64
systems.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

mmc: alcor: don't write data before command has completed

The alcor driver is setting up data transfer and submitting the associated
MMC command at the same time. While this works most of the time, it
occasionally causes problems upon write.

In the working case, after setting up the data transfer and submitting
the MMC command, an interrupt comes in a moment later with CMD_END and
WRITE_BUF_RDY bits set. The data transfer then happens without problem.

However, on occasion, the interrupt that arrives at that point only
has WRITE_BUF_RDY set. The hardware notifies that it's ready to write
data, but the associated MMC command is still running. Regardless, the
driver was proceeding to write data immediately, and that would then cause
another interrupt indicating data CRC error, and the write would fail.

Additionally, the transfer setup function alcor_trigger_data_transfer()
was being called 3 times for each write operation, which was confusing
and may be contributing to this issue.

Solve this by tweaking the driver behaviour to follow the sequence observed
in the original ampe_stor vendor driver:
1. When starting request handling, write 0 to DATA_XFER_CTRL
2. Submit the command
3. Wait for CMD_END interrupt and then trigger data transfer
4. For the PIO case, trigger the next step of the data transfer only
upon the following DATA_END interrupt, which occurs after the block has
been written.

I confirmed that the read path still works (DMA & PIO) and also now
presents more consistency with the operations performed by ampe_stor.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Fixes: c5413ad815a6 ("mmc: add new Alcor Micro Cardreader SD/MMC driver")
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: fix DMA reads

Setting max_blk_count to 1 here was causing the mmc block layer
to always use the MMC_READ_SINGLE_BLOCK command here, which the
driver does not DMA-accelerate.

Drop the max_blk_ settings here. The mmc host defaults suffice,
along with the max_segs and max_seg_size settings, which I have
now documented in more detail.

Now each MMC command reads 4 512-byte blocks, using DMA instead of
PIO. On my SD card, this increases read performance (measured with dd)
from 167kb/sec to 4.6mb/sec.

Link: http://lkml.kernel.org/r/CAD8Lp47L5T3jnAjBiPs1cQ+yFA3L6LJtgFvMETnBrY63-Zdi2g@mail.gmail.com
Signed-off-by: Daniel Drake <drake@endlessm.com>
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Fixes: c5413ad815a6 ("mmc: add new Alcor Micro Cardreader SD/MMC driver")
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: alcor: remove set but not used variables 'len, clock_out'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/mmc/host/alcor.c: In function 'alcor_data_set_dma':
drivers/mmc/host/alcor.c:124:12: warning:
variable 'len' set but not used [-Wunused-but-set-variable]

drivers/mmc/host/alcor.c:648:15: warning:
variable 'clock_out' set but not used [-Wunused-but-set-variable]

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: add new Alcor Micro Cardreader SD/MMC driver

This driver provides support for Alcor Micro AU6601 and AU6621
SD/MMC controller.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>