[PATCH v5 5/7] dmaengine: add function to provide per descriptor xfercap for dma engine

[Dave Jiang]

Adding a function that will export the transfer capability per descriptor
for a DMA device for the dmaengine subsystem.

Signed-off-by: Dave Jiang <dave.ji...@intel.com>
---
 drivers/dma/ioat/init.c   |    1 +
 include/linux/dmaengine.h |   10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
index 5c69ff6..4f24c36 100644
--- a/drivers/dma/ioat/init.c
+++ b/drivers/dma/ioat/init.c
@@ -596,6 +596,7 @@ static int ioat_enumerate_channels(struct ioatdma_device 
*ioat_dma)
        if (xfercap_log == 0)
                return 0;
        dev_dbg(dev, "%s: xfercap = %d\n", __func__, 1 << xfercap_log);
+       dma->xfercap = 1 << xfercap_log;
 
        for (i = 0; i < dma->chancnt; i++) {
                ioat_chan = devm_kzalloc(dev, sizeof(*ioat_chan), GFP_KERNEL);
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 0c91411..53356c4 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -743,6 +743,7 @@ struct dma_device {
        u32 max_burst;
        bool descriptor_reuse;
        enum dma_residue_granularity residue_granularity;
+       u64 xfercap;    /* descriptor transfer capability limit */
 
        int (*device_alloc_chan_resources)(struct dma_chan *chan);
        void (*device_free_chan_resources)(struct dma_chan *chan);
@@ -1326,6 +1327,11 @@ struct dma_chan *dma_request_chan_by_mask(const 
dma_cap_mask_t *mask);
 
 void dma_release_channel(struct dma_chan *chan);
 int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps);
+
+static inline u64 dma_get_desc_xfercap(struct dma_chan *chan)
+{
+       return chan->device->xfercap;
+}
 #else
 static inline struct dma_chan *dma_find_channel(enum dma_transaction_type 
tx_type)
 {
@@ -1370,6 +1376,10 @@ static inline int dma_get_slave_caps(struct dma_chan 
*chan,
 {
        return -ENXIO;
 }
+static inline u64 dma_get_desc_xfercap(struct dma_chan *chan)
+{
+       return -ENXIO;
+}
 #endif
 
 #define dma_request_slave_channel_reason(dev, name) dma_request_chan(dev, name)

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