ioat3: support xor via pq descriptors

If a platform advertises pq capabilities, but not xor, then use
ioat3_prep_pqxor and ioat3_prep_pqxor_val to simulate xor support.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c
index ca2af0f..bb57491 100644 (file)
--- a/drivers/dma/ioat/dma_v3.c
+++ b/drivers/dma/ioat/dma_v3.c
@@ -766,6 +766,44 @@ ioat3_prep_pq_val(struct dma_chan *chan, dma_addr_t *pq, dma_addr_t *src,
                                    flags);
 }
 
+static struct dma_async_tx_descriptor *
+ioat3_prep_pqxor(struct dma_chan *chan, dma_addr_t dst, dma_addr_t *src,
+                unsigned int src_cnt, size_t len, unsigned long flags)
+{
+       unsigned char scf[src_cnt];
+       dma_addr_t pq[2];
+
+       memset(scf, 0, src_cnt);
+       flags |= DMA_PREP_PQ_DISABLE_Q;
+       pq[0] = dst;
+       pq[1] = ~0;
+
+       return __ioat3_prep_pq_lock(chan, NULL, pq, src, src_cnt, scf, len,
+                                   flags);
+}
+
+struct dma_async_tx_descriptor *
+ioat3_prep_pqxor_val(struct dma_chan *chan, dma_addr_t *src,
+                    unsigned int src_cnt, size_t len,
+                    enum sum_check_flags *result, unsigned long flags)
+{
+       unsigned char scf[src_cnt];
+       dma_addr_t pq[2];
+
+       /* the cleanup routine only sets bits on validate failure, it
+        * does not clear bits on validate success... so clear it here
+        */
+       *result = 0;
+
+       memset(scf, 0, src_cnt);
+       flags |= DMA_PREP_PQ_DISABLE_Q;
+       pq[0] = src[0];
+       pq[1] = ~0;
+
+       return __ioat3_prep_pq_lock(chan, result, pq, &src[1], src_cnt - 1, scf,
+                                   len, flags);
+}
+
 static void __devinit ioat3_dma_test_callback(void *dma_async_param)
 {
        struct completion *cmp = dma_async_param;
@@ -1084,6 +1122,17 @@ int __devinit ioat3_dma_probe(struct ioatdma_device *device, int dca)
 
                dma_cap_set(DMA_PQ_VAL, dma->cap_mask);
                dma->device_prep_dma_pq_val = ioat3_prep_pq_val;
+
+               if (!(cap & IOAT_CAP_XOR)) {
+                       dma->max_xor = 8;
+                       dma->xor_align = 2;
+
+                       dma_cap_set(DMA_XOR, dma->cap_mask);
+                       dma->device_prep_dma_xor = ioat3_prep_pqxor;
+
+                       dma_cap_set(DMA_XOR_VAL, dma->cap_mask);
+                       dma->device_prep_dma_xor_val = ioat3_prep_pqxor_val;
+               }
        }
 
        /* -= IOAT ver.3 workarounds =- */