Implement device_channel_caps().
EDMA has a finite set of PaRAM slots available for linking
a multi-segment SG transfer. In order to prevent any one
channel from consuming all PaRAM slots to fulfill a large SG
transfer, the driver reports a static per-channel max number
of SG segments it will handle.
The maximum size of SG segment is limited by the slave config
maxburst and addr_width for the channel in question. These values
are used from the current channel config to calculate and return
the max segment length cap.
Signed-off-by: Matt Porter <mporter@xxxxxx>
---
drivers/dma/edma.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 47ba7bf..8b41045 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -70,6 +70,7 @@ struct edma_chan {
bool alloced;
int slot[EDMA_MAX_SLOTS];
struct dma_slave_config cfg;
+ struct dmaengine_chan_caps caps;
};
struct edma_cc {
@@ -462,6 +463,28 @@ static void edma_issue_pending(struct dma_chan *chan)
spin_unlock_irqrestore(&echan->vchan.lock, flags);
}
+static struct dmaengine_chan_caps
+*edma_get_channel_caps(struct dma_chan *chan, enum dma_transfer_direction dir)
+{
+ struct edma_chan *echan;
+ enum dma_slave_buswidth width = 0;
+ u32 burst = 0;
+
+ if (chan) {
+ echan = to_edma_chan(chan);
+ if (dir == DMA_MEM_TO_DEV) {
+ width = echan->cfg.dst_addr_width;
+ burst = echan->cfg.dst_maxburst;
+ } else if (dir == DMA_DEV_TO_MEM) {
+ width = echan->cfg.src_addr_width;
+ burst = echan->cfg.src_maxburst;
+ }
+ echan->caps.seg_len = (SZ_64K - 1) * width * burst;
+ return &echan->caps;
+ }
+ return NULL;
+}
+
static size_t edma_desc_size(struct edma_desc *edesc)
{
int i;
@@ -521,6 +544,8 @@ static void __init edma_chan_init(struct edma_cc *ecc,
echan->ch_num = EDMA_CTLR_CHAN(ecc->ctlr, i);
echan->ecc = ecc;
echan->vchan.desc_free = edma_desc_free;
+ echan->caps.ops = DMAENGINE_SLAVE | DMAENGINE_SG;
+ echan->caps.seg_nr = MAX_NR_SG;
vchan_init(&echan->vchan, dma);
@@ -537,6 +562,7 @@ static void edma_dma_init(struct edma_cc *ecc, struct dma_device *dma,
dma->device_alloc_chan_resources = edma_alloc_chan_resources;
dma->device_free_chan_resources = edma_free_chan_resources;
dma->device_issue_pending = edma_issue_pending;
+ dma->device_channel_caps = edma_get_channel_caps;
dma->device_tx_status = edma_tx_status;
dma->device_control = edma_control;
dma->dev = dev;
--
1.7.9.5
--
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