dma_slave_caps is very important to the generic layers that might interact with
dmaengine, such as ASoC. Unfortunately, it has been added as yet another
dma_device callback, and most of the existing drivers haven't implemented it,
reducing its reliability.
Introduce a generic behaviour to implement this, that rely on both the split of
device_control to derive which functions are supported and on new variables to
be set in the dma_device structure.
These variables holds what used to be the capabilities, that were set
per-channel. However, this proved to be a bit overkill, since every driver
filling these so far were hardcoding it, disregarding which channel was
actually given.
Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
---
include/linux/dmaengine.h | 41 +++++++++++++++++++++++++++++++++++++----
1 file changed, 37 insertions(+), 4 deletions(-)
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index b0efc805937a..be9e60aa8f5e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -593,6 +593,14 @@ struct dma_tx_state {
* @fill_align: alignment shift for memset operations
* @dev_id: unique device ID
* @dev: struct device reference for dma mapping api
+ * @src_addr_widths: bit mask of src addr widths the device supports
+ * @dst_addr_widths: bit mask of dst addr widths the device supports
+ * @directions: bit mask of slave direction the device supports since
+ * the enum dma_transfer_direction is not defined as bits for
+ * each type of direction, the dma controller should fill (1 <<
+ * <TYPE>) and same should be checked by controller as well
+ * @residue_granularity: granularity of the transfer residue reported
+ * by tx_status
* @device_alloc_chan_resources: allocate resources and return the
* number of allocated descriptors
* @device_free_chan_resources: release DMA channel's resources
@@ -642,6 +650,11 @@ struct dma_device {
int dev_id;
struct device *dev;
+ u32 src_addr_widths;
+ u32 dst_addr_widths;
+ u32 directions;
+ enum dma_residue_granularity residue_granularity;
+
int (*device_alloc_chan_resources)(struct dma_chan *chan);
void (*device_free_chan_resources)(struct dma_chan *chan);
@@ -783,17 +796,37 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_sg(
static inline int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
{
+ struct dma_device *device;
+
if (!chan || !caps)
return -EINVAL;
+ device = chan->device;
+
/* check if the channel supports slave transactions */
- if (!test_bit(DMA_SLAVE, chan->device->cap_mask.bits))
+ if (!test_bit(DMA_SLAVE, device->cap_mask.bits))
+ return -ENXIO;
+
+ if (device->device_slave_caps)
+ return device->device_slave_caps(chan, caps);
+
+ /*
+ * Check whether it reports it uses the generic slave
+ * capabilities, if not, that means it doesn't support any
+ * kind of slave capabilities reporting.
+ */
+ if (!device->directions)
return -ENXIO;
- if (chan->device->device_slave_caps)
- return chan->device->device_slave_caps(chan, caps);
+ caps->src_addr_widths = device->src_addr_widths;
+ caps->dst_addr_widths = device->dst_addr_widths;
+ caps->directions = device->directions;
+ caps->residue_granularity = device->residue_granularity;
+
+ caps->cmd_pause = !!device->device_pause;
+ caps->cmd_terminate = !!device->device_terminate_all;
- return -ENXIO;
+ return 0;
}
static inline int dmaengine_terminate_all(struct dma_chan *chan)
--
2.1.1
--
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