dmaengine: Rework dma_chan_get

dma_chan_get uses a rather interesting error handling and code path.

Change it to something more usual in the kernel.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
dmaengine: Make channel allocation callbacks optional

Nowadays, some drivers don't have anything in there channel allocation
callbacks anymore.

Remove the BUG_ON if those callbacks aren't implemented, in order to allow
drivers to not implement them.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
dmaengine: Introduce a device_config callback

The fact that the channel configuration is done in device_control is rather
misleading, since it's not really advertised as such, plus, the fact that the
framework exposes a function of its own makes it not really intuitive, while
we're losing the type checking whenever we pass that unsigned long argument.

Add a device_config callback to dma_device, with a fallback on the old
behaviour for now for existing drivers to opt in.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
dmaengine: split out pause/resume operations from device_control

Split out the pause and resume operations to callbacks of their own. In order
to preserve some backwark compatibility, the dmaengine_pause/dmaengine_resume
are still falling back on dmaengine_device_control.

Eventually, that will allow to get the device capabilities in a generic way,
removing the need to implement device_slave_caps.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
dmaengine: Add device_terminate_all callback

Split out the terminate_all command from device_control to a dma_device
callback. In order to preserve backward capability, still rely on
device_control if no such callback has been implemented.

Eventually, this will allow to create a generic dma_slave_caps callback.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
dmaengine: Remove the need to declare device_control

In order to migrate the drivers without triggering a BUG_ON for the converted
drivers, which would cause bisectability issues, we need to remove that check
before removing the device_control function entirely.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
dmaengine: Create a generic dma_slave_caps callback

dma_slave_caps is very important to the generic layers that might interact with
dmaengine, such as ASoC. Unfortunately, it has been added as yet another
dma_device callback, and most of the existing drivers haven't implemented it,
reducing its reliability.

Introduce a generic behaviour to implement this, that rely on both the split of
device_control to derive which functions are supported and on new variables to
be set in the dma_device structure.

These variables holds what used to be the capabilities, that were set
per-channel. However, this proved to be a bit overkill, since every driver
filling these so far were hardcoding it, disregarding which channel was
actually given.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: pl08x: Split device_control

Split the device_control callback of the AMBA PL08x DMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: hdmac: Split device_control

Split the device_control callback of the Atmel HDMAC driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: bcm2835: Split device_control

Split the device_control callback of the Broadcom BCM2835 DMA driver to make
use of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
dmaengine: coh901318: Split device_control

Split the device_control callback of the ST-Ericsson COH901318 DMA driver to
make use of the newly introduced callbacks, that will eventually be used to
retrieve slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
dmaengine: cppi41: Split device_control

Split the device_control callback of the TI CPPI41 DMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: jz4740: Split device_control

Split the device_control callback of the JZ4740 DMA driver to make use of the
newly introduced callbacks, that will eventually be used to retrieve slave
capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: dw: Split device_control

Split the device_control callback of the DesignWare DMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: edma: Split device_control

Split the device_control callback of the TI EDMA driver to make use of the
newly introduced callbacks, that will eventually be used to retrieve slave
capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: ep93xx: Split device_control

Split the device_control callback of the Cirrus Logic EP93xx driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: fsl-edma: Split device_control

Split the device_control callback of the Freescale EDMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: imx: Split device_control

Split the device_control callback of the Freescale IMX DMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: imx-sdma: Split device_control

Split the device_control callback of the Freescale IMX SDMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
dmaengine: intel-mid-dma: Split device_control

Split the device_control callback of the Intel MID DMA driver to make use
of the newly introduced callbacks, that will eventually be used to retrieve
slave capabilities.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>