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SubjectRe: [PATCH v3 6/8] dmaengine: rcar-dmac: add iommu support for slave transfers
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On 10/02/16 00:57, Niklas Söderlund wrote:
> Enable slave transfers to devices behind IPMMU:s by mapping the slave
> addresses using the dma-mapping API.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
> drivers/dma/sh/rcar-dmac.c | 57 ++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 52 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 743873c..268407c 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1106,21 +1106,68 @@ rcar_dmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
> return desc;
> }
>
> +static int rcar_dmac_set_slave_addr(struct dma_chan *chan,
> + struct rcar_dmac_chan_slave *slave,
> + phys_addr_t addr, size_t size)
> +{
> + struct dma_attrs attrs;
> + enum dma_data_direction dir;
> +
> + init_dma_attrs(&attrs);
> + dma_set_attr(DMA_ATTR_NO_KERNEL_MAPPING, &attrs);
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);

Now that we have a way to deal with MMIO addresses properly, we don't
need these any more.

Robin.

> +
> + /*
> + * We can't know the direction at this time, see documentation for
> + * 'direction' in struct dma_slave_config.
> + */
> + dir = DMA_BIDIRECTIONAL;
> +
> + if (slave->xfer_size) {
> + dma_unmap_resource(chan->device->dev, slave->slave_addr,
> + slave->xfer_size, dir, &attrs);
> + slave->slave_addr = 0;
> + slave->xfer_size = 0;
> + }
> +
> + if (size) {
> + slave->slave_addr = dma_map_resource(chan->device->dev, addr,
> + size, dir, &attrs);
> +
> + if (dma_mapping_error(chan->device->dev, slave->slave_addr)) {
> + struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
> +
> + dev_err(chan->device->dev,
> + "chan%u: failed to map %zx@%pap",
> + rchan->index, size, &addr);
> + return -EIO;
> + }
> +
> + slave->xfer_size = size;
> + }
> +
> + return 0;
> +}
> +
> static int rcar_dmac_device_config(struct dma_chan *chan,
> struct dma_slave_config *cfg)
> {
> struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
> + int ret;
>
> /*
> * We could lock this, but you shouldn't be configuring the
> * channel, while using it...
> */
> - rchan->src.slave_addr = cfg->src_addr;
> - rchan->dst.slave_addr = cfg->dst_addr;
> - rchan->src.xfer_size = cfg->src_addr_width;
> - rchan->dst.xfer_size = cfg->dst_addr_width;
>
> - return 0;
> + ret = rcar_dmac_set_slave_addr(chan, &rchan->src, cfg->src_addr,
> + cfg->src_addr_width);
> + if (ret)
> + return ret;
> +
> + ret = rcar_dmac_set_slave_addr(chan, &rchan->dst, cfg->dst_addr,
> + cfg->dst_addr_width);
> + return ret;
> }
>
> static int rcar_dmac_chan_terminate_all(struct dma_chan *chan)
>

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