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>

1 files changed, 79 insertions, 0 deletions

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index cad18f3660ae..4e55239c7a30 100644
--- 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;
         }