[PATCH 4/5] dmaengine: edma: Implement device_get_max_len callback

[Peter Ujfalusi]

eDMA can support maximum of 65535 number of bursts in one transfer.
The limitation is because the CCNT counter is 16bit unsigned.

Signed-off-by: Peter Ujfalusi <peter.ujfal...@ti.com>
---
 drivers/dma/edma.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 6970355abdc9..14c52574262c 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -900,6 +900,28 @@ static int edma_slave_config(struct dma_chan *chan,
        return 0;
 }
 
+static u32 edma_get_max_len(struct dma_chan *chan,
+                           enum dma_transfer_direction dir)
+{
+       struct edma_chan *echan = to_edma_chan(chan);
+       enum dma_slave_buswidth dev_width;
+       u32 burst;
+
+       if (!is_slave_direction(dir))
+               return 0;
+
+       if (dir == DMA_DEV_TO_MEM) {
+               dev_width = echan->cfg.src_addr_width;
+               burst = echan->cfg.src_maxburst;
+       } else {
+               burst = echan->cfg.dst_maxburst;
+               dev_width = echan->cfg.dst_addr_width;
+       }
+
+       /* CCNT: 16bit unsigned. Number of bursts */
+       return dev_width * burst * (SZ_64K - 1);
+}
+
 static int edma_dma_pause(struct dma_chan *chan)
 {
        struct edma_chan *echan = to_edma_chan(chan);
@@ -1850,6 +1872,7 @@ static void edma_dma_init(struct edma_cc *ecc, bool 
legacy_mode)
        s_ddev->device_issue_pending = edma_issue_pending;
        s_ddev->device_tx_status = edma_tx_status;
        s_ddev->device_config = edma_slave_config;
+       s_ddev->device_get_max_len = edma_get_max_len;
        s_ddev->device_pause = edma_dma_pause;
        s_ddev->device_resume = edma_dma_resume;
        s_ddev->device_terminate_all = edma_terminate_all;
-- 
2.14.1


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