[PATCH] DMAEngine: sirf: add DMA pause/resume support

[PATCH] DMAEngine: sirf: add DMA pause/resume support

[Barry Song]

From: Barry Song <Baohua.Song@csr.com>

pause/resume are important for users like sound drivers,
this patches make the sirf prima2/marco support

Signed-off-by: Barry Song <Baohua.Song@csr.com>
---
 drivers/dma/sirf-dma.c |   36 ++++++++++++++++++++++++++++++++++++
 1 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
index 212f69f..ffe05bb 100644
--- a/drivers/dma/sirf-dma.c
+++ b/drivers/dma/sirf-dma.c
@@ -313,6 +313,38 @@ static int sirfsoc_dma_terminate_all(struct sirfsoc_dma_chan *schan)
 	return 0;
 }
 
+static int sirfsoc_dma_pause_chan(struct sirfsoc_dma_chan *schan)
+{
+	struct sirfsoc_dma *sdma = dma_chan_to_sirfsoc_dma(&schan->chan);
+	int cid = schan->chan.chan_id;
+
+	if (!sdma->is_marco)
+		writel_relaxed(readl_relaxed(sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL)
+			& ~((1 << cid) | 1 << (cid + 16)),
+			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL);
+	else
+		writel_relaxed((1 << cid) | 1 << (cid + 16),
+			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL_CLR);
+
+	return 0;
+}
+
+static int sirfsoc_dma_resume_chan(struct sirfsoc_dma_chan *schan)
+{
+	struct sirfsoc_dma *sdma = dma_chan_to_sirfsoc_dma(&schan->chan);
+	int cid = schan->chan.chan_id;
+
+	if (!sdma->is_marco)
+		writel_relaxed(readl_relaxed(sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL)
+			| ((1 << cid) | 1 << (cid + 16)),
+			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL);
+	else
+		writel_relaxed((1 << cid) | 1 << (cid + 16),
+			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL);
+
+	return 0;
+}
+
 static int sirfsoc_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 	unsigned long arg)
 {
@@ -320,6 +352,10 @@ static int sirfsoc_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 	struct sirfsoc_dma_chan *schan = dma_chan_to_sirfsoc_dma_chan(chan);
 
 	switch (cmd) {
+	case DMA_PAUSE:
+		return sirfsoc_dma_pause_chan(schan);
+	case DMA_RESUME:
+		return sirfsoc_dma_resume_chan(schan);
 	case DMA_TERMINATE_ALL:
 		return sirfsoc_dma_terminate_all(schan);
 	case DMA_SLAVE_CONFIG:
-- 
1.7.5.4



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[PATCH] DMAEngine: sirf: add DMA pause/resume support

[Russell King - ARM Linux]

On Fri, Dec 14, 2012 at 05:44:42PM +0800, Barry Song wrote:
> diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
> index 212f69f..ffe05bb 100644
> --- a/drivers/dma/sirf-dma.c
> +++ b/drivers/dma/sirf-dma.c
> @@ -313,6 +313,38 @@ static int sirfsoc_dma_terminate_all(struct sirfsoc_dma_chan *schan)
>  	return 0;
>  }
>  
> +static int sirfsoc_dma_pause_chan(struct sirfsoc_dma_chan *schan)
> +{
> +	struct sirfsoc_dma *sdma = dma_chan_to_sirfsoc_dma(&schan->chan);
> +	int cid = schan->chan.chan_id;
> +
> +	if (!sdma->is_marco)
> +		writel_relaxed(readl_relaxed(sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL)
> +			& ~((1 << cid) | 1 << (cid + 16)),
> +			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL);
> +	else
> +		writel_relaxed((1 << cid) | 1 << (cid + 16),
> +			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL_CLR);

You're doing a read-modify-write to what looks like a shared register.
What makes this code safe in a preempt or SMP environment?

[PATCH] DMAEngine: sirf: add DMA pause/resume support

[Barry Song]

2012/12/14, Russell King - ARM Linux <linux@arm.linux.org.uk>:
> On Fri, Dec 14, 2012 at 05:44:42PM +0800, Barry Song wrote:
>> diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
>> index 212f69f..ffe05bb 100644
>> --- a/drivers/dma/sirf-dma.c
>> +++ b/drivers/dma/sirf-dma.c
>> @@ -313,6 +313,38 @@ static int sirfsoc_dma_terminate_all(struct
>> sirfsoc_dma_chan *schan)
>>  	return 0;
>>  }
>>
>> +static int sirfsoc_dma_pause_chan(struct sirfsoc_dma_chan *schan)
>> +{
>> +	struct sirfsoc_dma *sdma = dma_chan_to_sirfsoc_dma(&schan->chan);
>> +	int cid = schan->chan.chan_id;
>> +
>> +	if (!sdma->is_marco)
>> +		writel_relaxed(readl_relaxed(sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL)
>> +			& ~((1 << cid) | 1 << (cid + 16)),
>> +			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL);
>> +	else
>> +		writel_relaxed((1 << cid) | 1 << (cid + 16),
>> +			sdma->base + SIRFSOC_DMA_CH_LOOP_CTRL_CLR);
>
> You're doing a read-modify-write to what looks like a shared register.
> What makes this code safe in a preempt or SMP environment?

the new registers of SiRFmarco split into SET and CLR instead of old
read-modify-write. anyway, here i missed holding a spinlock for
SiRFprimaII.

-barry