dmaengine: hdmac: Add scatter-gathered memset support

Just like memset support, the HDMAC might be used to do a memset over a
discontiguous memory area.

In such a case, we'll just build up a chain of memset descriptors over the
contiguous chunks of memory to set, in order to allow such a support.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index cad18f3..4e55239 100644 (file)
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -986,6 +986,83 @@ err_free_buffer:
        return NULL;
 }
 
+static struct dma_async_tx_descriptor *
+atc_prep_dma_memset_sg(struct dma_chan *chan,
+                      struct scatterlist *sgl,
+                      unsigned int sg_len, int value,
+                      unsigned long flags)
+{
+       struct at_dma_chan      *atchan = to_at_dma_chan(chan);
+       struct at_dma           *atdma = to_at_dma(chan->device);
+       struct at_desc          *desc = NULL, *first = NULL, *prev = NULL;
+       struct scatterlist      *sg;
+       void __iomem            *vaddr;
+       dma_addr_t              paddr;
+       size_t                  total_len = 0;
+       int                     i;
+
+       dev_vdbg(chan2dev(chan), "%s: v0x%x l0x%zx f0x%lx\n", __func__,
+                value, sg_len, flags);
+
+       if (unlikely(!sgl || !sg_len)) {
+               dev_dbg(chan2dev(chan), "%s: scatterlist is empty!\n",
+                       __func__);
+               return NULL;
+       }
+
+       vaddr = dma_pool_alloc(atdma->memset_pool, GFP_ATOMIC, &paddr);
+       if (!vaddr) {
+               dev_err(chan2dev(chan), "%s: couldn't allocate buffer\n",
+                       __func__);
+               return NULL;
+       }
+       *(u32*)vaddr = value;
+
+       for_each_sg(sgl, sg, sg_len, i) {
+               dma_addr_t dest = sg_dma_address(sg);
+               size_t len = sg_dma_len(sg);
+
+               dev_vdbg(chan2dev(chan), "%s: d0x%08x, l0x%zx\n",
+                        __func__, dest, len);
+
+               if (!is_dma_fill_aligned(chan->device, dest, 0, len)) {
+                       dev_err(chan2dev(chan), "%s: buffer is not aligned\n",
+                               __func__);
+                       goto err_put_desc;
+               }
+
+               desc = atc_create_memset_desc(chan, paddr, dest, len);
+               if (!desc)
+                       goto err_put_desc;
+
+               atc_desc_chain(&first, &prev, desc);
+
+               total_len += len;
+       }
+
+       /*
+        * Only set the buffer pointers on the last descriptor to
+        * avoid free'ing while we have our transfer still going
+        */
+       desc->memset_paddr = paddr;
+       desc->memset_vaddr = vaddr;
+       desc->memset_buffer = true;
+
+       first->txd.cookie = -EBUSY;
+       first->total_len = total_len;
+
+       /* set end-of-link on the descriptor */
+       set_desc_eol(desc);
+
+       first->txd.flags = flags;
+
+       return &first->txd;
+
+err_put_desc:
+       atc_desc_put(atchan, first);
+       return NULL;
+}
+
 /**
  * atc_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
  * @chan: DMA channel
@@ -1868,6 +1945,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
        dma_cap_set(DMA_INTERLEAVE, at91sam9g45_config.cap_mask);
        dma_cap_set(DMA_MEMCPY, at91sam9g45_config.cap_mask);
        dma_cap_set(DMA_MEMSET, at91sam9g45_config.cap_mask);
+       dma_cap_set(DMA_MEMSET_SG, at91sam9g45_config.cap_mask);
        dma_cap_set(DMA_PRIVATE, at91sam9g45_config.cap_mask);
        dma_cap_set(DMA_SLAVE, at91sam9g45_config.cap_mask);
        dma_cap_set(DMA_SG, at91sam9g45_config.cap_mask);
@@ -1989,6 +2067,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
 
        if (dma_has_cap(DMA_MEMSET, atdma->dma_common.cap_mask)) {
                atdma->dma_common.device_prep_dma_memset = atc_prep_dma_memset;
+               atdma->dma_common.device_prep_dma_memset_sg = atc_prep_dma_memset_sg;
                atdma->dma_common.fill_align = DMAENGINE_ALIGN_4_BYTES;
        }