[PATCH v7 1/7] dmaengine: dw-edma: Add a channel transfer size operation

[Koichiro Den <den@valinux.co.jp>]

Expose the channel transfer size through a core operation for eDMA and
HDMA. LL progress handling will use it to check for a stopped channel
with no payload left to transfer.

PCI Express DM Controller Databook 6.10a-lca06, section 7.3.4,
"Detecting the End of the HDMA Transfer", documents this polling method:

  STATUS field of the HDMA Write/Read Channel Status register
  (HDMA_STATUS_OFF_[WR|RD]CH_i) is Stopped, and the HDMA Transfer Size
  register is 0x0.

The same condition applies to eDMA as well.

No functional change on its own.

Cc: stable@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
Changes from v6:
  - Add Frank's Reviewed-by.
  - Add Cc:stable because patch 2 depends on this change.
  - No code changes.

 drivers/dma/dw-edma/dw-edma-core.h    | 6 ++++++
 drivers/dma/dw-edma/dw-edma-v0-core.c | 6 ++++++
 drivers/dma/dw-edma/dw-hdma-v0-core.c | 6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index 76fd5a41a707..84a811bdcb6d 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -163,6 +163,7 @@ struct dw_edma_core_ops {
 	int (*ch_quiesce)(struct dw_edma_chan *chan);
 	u16 (*ch_count)(struct dw_edma *dw, enum dw_edma_dir dir);
 	enum dma_status (*ch_status)(struct dw_edma_chan *chan);
+	u32 (*ch_transfer_size)(struct dw_edma_chan *chan);
 	irqreturn_t (*handle_int)(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
 				  dw_edma_handler_t handler);
 	void (*non_ll_start)(struct dw_edma_chan *chan, struct dw_edma_burst *child);
@@ -262,6 +263,11 @@ enum dma_status dw_edma_core_ch_status(struct dw_edma_chan *chan)
 	return chan->dw->core->ch_status(chan);
 }
 
+static inline u32 dw_edma_core_ch_transfer_size(struct dw_edma_chan *chan)
+{
+	return chan->dw->core->ch_transfer_size(chan);
+}
+
 static inline irqreturn_t
 dw_edma_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
 			dw_edma_handler_t handler)
diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
index c053cb4c2844..fa8be85c7ac1 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -318,6 +318,11 @@ static enum dma_status dw_edma_v0_core_ch_status(struct dw_edma_chan *chan)
 		return DMA_ERROR;
 }
 
+static u32 dw_edma_v0_core_ch_transfer_size(struct dw_edma_chan *chan)
+{
+	return GET_CH_32(chan->dw, chan->dir, chan->id, transfer_size);
+}
+
 static void dw_edma_v0_core_clear_done_int(struct dw_edma_chan *chan)
 {
 	struct dw_edma *dw = chan->dw;
@@ -665,6 +670,7 @@ static const struct dw_edma_core_ops dw_edma_v0_core = {
 	.ch_quiesce = dw_edma_v0_core_ch_quiesce,
 	.ch_count = dw_edma_v0_core_ch_count,
 	.ch_status = dw_edma_v0_core_ch_status,
+	.ch_transfer_size = dw_edma_v0_core_ch_transfer_size,
 	.handle_int = dw_edma_v0_core_handle_int,
 	.ll_data = dw_edma_v0_core_ll_data,
 	.ll_link = dw_edma_v0_core_ll_link,
diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
index d42cb4ad49a2..aa430219d0af 100644
--- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
@@ -156,6 +156,11 @@ static enum dma_status dw_hdma_v0_core_ch_status(struct dw_edma_chan *chan)
 		return DMA_ERROR;
 }
 
+static u32 dw_hdma_v0_core_ch_transfer_size(struct dw_edma_chan *chan)
+{
+	return GET_CH_32(chan->dw, chan->dir, chan->id, transfer_size);
+}
+
 static void dw_hdma_v0_core_clear_done_int(struct dw_edma_chan *chan)
 {
 	struct dw_edma *dw = chan->dw;
@@ -425,6 +430,7 @@ static const struct dw_edma_core_ops dw_hdma_v0_core = {
 	.ch_quiesce = dw_hdma_v0_core_ch_quiesce,
 	.ch_count = dw_hdma_v0_core_ch_count,
 	.ch_status = dw_hdma_v0_core_ch_status,
+	.ch_transfer_size = dw_hdma_v0_core_ch_transfer_size,
 	.handle_int = dw_hdma_v0_core_handle_int,
 	.non_ll_start = dw_hdma_v0_core_non_ll_start,
 	.ll_data = dw_hdma_v0_core_ll_data,
-- 
2.54.0