Add support for cyclic DMA on sa11x0 platforms. This follows the
discussed behaviour that the callback will be called at some point
after period expires, and may coalesce multiple period expiries into
one callback (due to the tasklet behaviour.)
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The semantics now implemented are:
- If the cookie has completed successfully, the residue will be zero.
- If the cookie is in progress or the channel is paused, it will be the
number of bytes yet to be transferred. [*]
- If the cookie is queued, it will be the number of bytes in the
descriptor.
* - where this is the number of bytes yet to be transferred to/from
RAM.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Split the virtual slave channel DMA support from the sa11x0 driver so
this code can be shared with other slave DMA engine drivers.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The recent merge of the sa11x0 code into mainline had silent conflicts
with further development of the DMA engine API, leading to build errors
and warnings:
drivers/net/irda/sa1100_ir.c: In function 'sa1100_irda_dma_start':
drivers/net/irda/sa1100_ir.c:151: error: too few arguments to function 'chan->device->device_prep_slave_sg'
drivers/dma/sa11x0-dma.c: In function 'sa11x0_dma_probe':
drivers/dma/sa11x0-dma.c:950: warning: assignment from incompatible pointer type
Fix these.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add support for the SA-11x0 DMA driver, which replaces the private
API version in arch/arm/mach-sa1100/dma.c.
We model this as a set of virtual DMA channels, one for each request
signal, and assign the virtual DMA channel to a physical DMA channel
when there is work to be done. This allows DMA users to claim their
channels, and hold them while not in use, without affecting the
availability of the physical channels.
Another advantage over this approach, compared to the private version,
is that a channel can be reconfigured on the fly without having to
release and re-request it - which for the IrDA driver, allows us to
use DMA for SIR mode transmit without eating up three physical
channels. As IrDA is half-duplex, we actually only need one physical
channel, and this architecture allows us to achieve that.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
