[PATCH 01/15] dmaengine: dw-edma: Cache DMA channel IDs in dw_edma_chip

[Koichiro Den]

The exported-DMA path needs to describe each exposed descriptor window
with the DMAEngine channel ID that owns it. Those IDs are only assigned
once the channels have been registered.

Cache the dma_chan IDs in dw_edma_chip after registration so controller
frontends can later publish them as auxiliary-resource metadata without
reaching back into the live channel objects.

Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
 drivers/dma/dw-edma/dw-edma-core.c | 18 +++++++++++++++++-
 include/linux/dma/edma.h           |  4 ++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index cd34a3ea602d..a13beacce2e7 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -837,6 +837,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
 	struct dma_device *dma;
 	u32 i, ch_cnt;
 	u32 pos;
+	int ret;
 
 	ch_cnt = dw->wr_ch_cnt + dw->rd_ch_cnt;
 	dma = &dw->dma;
@@ -932,7 +933,22 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
 	dma_set_max_seg_size(dma->dev, U32_MAX);
 
 	/* Register DMA device */
-	return dma_async_device_register(dma);
+	ret = dma_async_device_register(dma);
+	if (ret)
+		return ret;
+
+	/* Cache dma_chan.id in dw_edma_chip */
+	for (i = 0; i < ch_cnt; i++) {
+		chan = &dw->chan[i];
+
+		if (i < dw->wr_ch_cnt)
+			chip->chan_ids_wr[i] = chan->vc.chan.chan_id;
+		else
+			chip->chan_ids_rd[i - dw->wr_ch_cnt] =
+						chan->vc.chan.chan_id;
+	}
+
+	return 0;
 }
 
 static inline void dw_edma_dec_irq_alloc(int *nr_irqs, u32 *alloc, u16 cnt)
diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
index 9da53c75e49b..0b861e8d305e 100644
--- a/include/linux/dma/edma.h
+++ b/include/linux/dma/edma.h
@@ -100,6 +100,10 @@ struct dw_edma_chip {
 	int			db_irq;
 	resource_size_t		db_offset;
 
+	/* dma_chan ids */
+	int			chan_ids_wr[EDMA_MAX_WR_CH];
+	int			chan_ids_rd[EDMA_MAX_RD_CH];
+
 	enum dw_edma_map_format	mf;
 
 	struct dw_edma		*dw;
-- 
2.51.0