DMA: get current descriptor data transfer count

Commit Message

Song, Elen Sept. 7, 2012, 10 a.m. UTC

when data transfer by dma, we could know how many data transfered in one descriptor read DMAC_CTRLAx's btsize bit to get dma transfer size in this case, we could know how many data have been transfered even transaction timeout

Signed-off-by: Elen Song <[e-mail]>
---
 drivers/dma/at_hdmac.c    |   18 ++++++++++++++++++
 include/linux/dmaengine.h |    2 ++
 2 files changed, 20 insertions(+)

 	dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
 	dma_async_tx_callback callback;
 	void *callback_param;
+	int (*get_count)(struct dma_async_tx_descriptor *tx);
 #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
 	struct dma_async_tx_descriptor *next;
 	struct dma_async_tx_descriptor *parent;
--
1.7.10

Comments

Russell King - ARM Linux Sept. 7, 2012, 10:36 a.m. UTC | #1

On Fri, Sep 07, 2012 at 10:00:44AM +0000, Song, Elen wrote:
> 
> when data transfer by dma, we could know how many data transfered in one descriptor read DMAC_CTRLAx's btsize bit to get dma transfer size in this case, we could know how many data have been transfered even transaction timeout
> 
> Signed-off-by: Elen Song <[e-mail]>

NAK, please use the established API for this.

Patch

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index 3934fcc..2099613 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -53,6 +53,7 @@  MODULE_PARM_DESC(init_nr_desc_per_channel,
 
 /* prototypes */
 static dma_cookie_t atc_tx_submit(struct dma_async_tx_descriptor *tx);
+static int atc_get_count(struct dma_async_tx_descriptor *tx);
 
 
 /*----------------------------------------------------------------------*/
@@ -95,6 +96,7 @@  static struct at_desc *atc_alloc_descriptor(struct dma_chan *chan,
 		desc->txd.flags = DMA_CTRL_ACK;
 		desc->txd.tx_submit = atc_tx_submit;
 		desc->txd.phys = phys;
+		desc->txd.get_count = atc_get_count;
 	}
 
 	return desc;
@@ -229,6 +231,22 @@  static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first)
 	vdbg_dump_regs(atchan);
 }
 
+/*
+ * atc_get_count - get current descriptor transfer data count
+ * @tx: current descriptor
+ */
+static int atc_get_count(struct dma_async_tx_descriptor *tx) {
+	struct at_dma_chan      *atchan = to_at_dma_chan(tx->chan);
+	int ctrla, btsize;
+
+	ctrla = channel_readl(atchan, CTRLA);
+	/* btsize is incremental until data transfer complete*/
+	btsize = ctrla & ATC_BTSIZE_MAX;
+
+	return btsize;
+}
+
 /**
  * atc_chain_complete - finish work for one transaction chain
  * @atchan: channel we work on
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 9c02a45..c719fff 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -404,6 +404,7 @@  typedef void (*dma_async_tx_callback)(void *dma_async_param);
  * @tx_submit: set the prepared descriptor(s) to be executed by the engine
  * @callback: routine to call after this operation is complete
  * @callback_param: general parameter to pass to the callback routine
+ * @get_count: get current descriptor data transfer count
  * ---async_tx api specific fields---
  * @next: at completion submit this descriptor
  * @parent: pointer to the next level up in the dependency chain @@ -417,6 +418,7 @@ struct dma_async_tx_descriptor {