[PATCH v3 1/3] dmaengine: add dma_get_slave_sg_caps()
Add a dmaengine API to retrieve slave SG transfer capabilities.
The API is optionally implemented by dmaengine drivers and when
unimplemented will return a NULL pointer. A client driver using
this API provides the required dma channel, address width, and
burst size of the transfer. dma_get_slave_sg_caps() returns an
SG caps structure with the maximum number and size of SG segments
that the given channel can handle.
Signed-off-by: Matt Porter
---
include/linux/dmaengine.h | 40
1 file changed, 40 insertions(+)
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index d3201e4..5b5b220 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -371,6 +371,19 @@ struct dma_slave_config {
unsigned int slave_id;
};
+/* struct dma_slave_sg_caps - expose SG transfer capability of a
+ * channel.
+ *
+ * @max_seg_nr: maximum number of SG segments supported on a SG/SLAVE
+ * channel (0 for no maximum or not a SG/SLAVE channel)
+ * @max_seg_len: maximum length of SG segments supported on a SG/SLAVE
+ * channel (0 for no maximum or not a SG/SLAVE channel)
+ */
+struct dma_slave_sg_caps {
+ u32 max_seg_nr;
+ u32 max_seg_len;
+};
+
static inline const char *dma_chan_name(struct dma_chan *chan)
{
return dev_name(&chan->dev->device);
@@ -534,6 +547,7 @@ struct dma_tx_state {
* struct with auxiliary transfer status information, otherwise the call
* will just return a simple status code
* @device_issue_pending: push pending transactions to hardware
+ * @device_slave_sg_caps: return the slave SG capabilities
*/
struct dma_device {
@@ -602,6 +616,9 @@ struct dma_device {
dma_cookie_t cookie,
struct dma_tx_state *txstate);
void (*device_issue_pending)(struct dma_chan *chan);
+ struct dma_slave_sg_caps *(*device_slave_sg_caps)(
+ struct dma_chan *chan, enum dma_slave_buswidth addr_width,
+ u32 maxburst);
};
static inline int dmaengine_device_control(struct dma_chan *chan,
@@ -969,6 +986,29 @@ dma_set_tx_state(struct dma_tx_state *st, dma_cookie_t
last, dma_cookie_t used,
}
}
+/**
+ * dma_get_slave_sg_caps - get DMAC SG transfer capabilities
+ * @chan: target DMA channel
+ * @addr_width: address width of the DMA transfer
+ * @maxburst: maximum DMA transfer burst size
+ *
+ * Get SG transfer capabilities for a specified channel. If the dmaengine
+ * driver does not implement SG transfer capabilities then NULL is
+ * returned.
+ */
+static inline struct dma_slave_sg_caps
+*dma_get_slave_sg_caps(struct dma_chan *chan,
+ enum dma_slave_buswidth addr_width,
+ u32 maxburst)
+{
+ if (chan->device->device_slave_sg_caps)
+ return chan->device->device_slave_sg_caps(chan,
+ addr_width,
+ maxburst);
+
+ return NULL;
+}
+
enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
#ifdef CONFIG_DMA_ENGINE
enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
--
1.7.9.5
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Re: [PATCH v3 1/3] dmaengine: add dma_get_slave_sg_caps()
On Mon, Feb 04, 2013 at 02:47:02PM -0500, Matt Porter wrote:
> Add a dmaengine API to retrieve slave SG transfer capabilities.
>
> The API is optionally implemented by dmaengine drivers and when
> unimplemented will return a NULL pointer. A client driver using
> this API provides the required dma channel, address width, and
> burst size of the transfer. dma_get_slave_sg_caps() returns an
> SG caps structure with the maximum number and size of SG segments
> that the given channel can handle.
Okay this sounds much better :-)
few points though:
- you added API for caps, but is actually calculating for given configuration
the max allowed range. IMHO that is not caps, perhaps renaming to get_max_sg
/some_better_name would be more apt.
- Still I like the idea of caps, but it should give H/W support capablity. If
you want to add that, pls develop on same line...
--
~Vinod
>
> Signed-off-by: Matt Porter
> ---
> include/linux/dmaengine.h | 40
> 1 file changed, 40 insertions(+)
>
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index d3201e4..5b5b220 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -371,6 +371,19 @@ struct dma_slave_config {
> unsigned int slave_id;
> };
>
> +/* struct dma_slave_sg_caps - expose SG transfer capability of a
> + * channel.
> + *
> + * @max_seg_nr: maximum number of SG segments supported on a SG/SLAVE
> + * channel (0 for no maximum or not a SG/SLAVE channel)
> + * @max_seg_len: maximum length of SG segments supported on a SG/SLAVE
> + *channel (0 for no maximum or not a SG/SLAVE channel)
> + */
> +struct dma_slave_sg_caps {
> + u32 max_seg_nr;
> + u32 max_seg_len;
> +};
> +
> static inline const char *dma_chan_name(struct dma_chan *chan)
> {
> return dev_name(&chan->dev->device);
> @@ -534,6 +547,7 @@ struct dma_tx_state {
> * struct with auxiliary transfer status information, otherwise the call
> * will just return a simple status code
> * @device_issue_pending: push pending transactions to hardware
> + * @device_slave_sg_caps: return the slave SG capabilities
> */
> struct dma_device {
>
> @@ -602,6 +616,9 @@ struct dma_device {
> dma_cookie_t cookie,
> struct dma_tx_state *txstate);
> void (*device_issue_pending)(struct dma_chan *chan);
> + struct dma_slave_sg_caps *(*device_slave_sg_caps)(
> + struct dma_chan *chan, enum dma_slave_buswidth addr_width,
> + u32 maxburst);
> };
>
> static inline int dmaengine_device_control(struct dma_chan *chan,
> @@ -969,6 +986,29 @@ dma_set_tx_state(struct dma_tx_state *st, dma_cookie_t
> last, dma_cookie_t used,
> }
> }
>
> +/**
> + * dma_get_slave_sg_caps - get DMAC SG transfer capabilities
> + * @chan: target DMA channel
> + * @addr_width: address width of the DMA transfer
> + * @maxburst: maximum DMA transfer burst size
> + *
> + * Get SG transfer capabilities for a specified channel. If the dmaengine
> + * driver does not implement SG transfer capabilities then NULL is
> + * returned.
> + */
> +static inline struct dma_slave_sg_caps
> +*dma_get_slave_sg_caps(struct dma_chan *chan,
> +enum dma_slave_buswidth addr_width,
> +u32 maxburst)
> +{
> + if (chan->device->device_slave_sg_caps)
> + return chan->device->device_slave_sg_caps(chan,
> + addr_width,
> + maxburst);
> +
> + return NULL;
> +}
> +
> enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
> #ifdef CONFIG_DMA_ENGINE
> enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
> --
> 1.7.9.5
>
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Re: [PATCH v3 1/3] dmaengine: add dma_get_slave_sg_caps()
On Tue, Feb 12, 2013 at 05:08:44PM +, Vinod Koul wrote: > On Mon, Feb 04, 2013 at 02:47:02PM -0500, Matt Porter wrote: > > Add a dmaengine API to retrieve slave SG transfer capabilities. > > > > The API is optionally implemented by dmaengine drivers and when > > unimplemented will return a NULL pointer. A client driver using > > this API provides the required dma channel, address width, and > > burst size of the transfer. dma_get_slave_sg_caps() returns an > > SG caps structure with the maximum number and size of SG segments > > that the given channel can handle. > Okay this sounds much better :-) > > few points though: > - you added API for caps, but is actually calculating for given configuration > the max allowed range. IMHO that is not caps, perhaps renaming to get_max_sg > /some_better_name would be more apt. I went with get_slave_sg_limits(), seemed pretty descriptive. Just posted v4 with that change. > - Still I like the idea of caps, but it should give H/W support capablity. If > you want to add that, pls develop on same line... Ok, seems like a good separate submission. -Matt ___ Davinci-linux-open-source mailing list Davinci-linux-open-source@linux.davincidsp.com http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
