Merge branch 'topic/api_caps' into for-linus

2 files changed, 71 insertions, 0 deletions

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index cfd2d703fcb5..36ed30116ee0 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2870,6 +2870,32 @@ static irqreturn_t pl330_irq_handler(int irq, void *data)
 		return IRQ_NONE;
 }
 
+#define PL330_DMA_BUSWIDTHS \
+	BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) | \
+	BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
+	BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
+	BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) | \
+	BIT(DMA_SLAVE_BUSWIDTH_8_BYTES)
+
+static int pl330_dma_device_slave_caps(struct dma_chan *dchan,
+	struct dma_slave_caps *caps)
+{
+	caps->src_addr_widths = PL330_DMA_BUSWIDTHS;
+	caps->dstn_addr_widths = PL330_DMA_BUSWIDTHS;
+	caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	caps->cmd_pause = false;
+	caps->cmd_terminate = true;
+
+	/*
+	 * This is the limit for transfers with a buswidth of 1, larger
+	 * buswidths will have larger limits.
+	 */
+	caps->max_sg_len = 1900800;
+	caps->max_sg_nr = 0;
+
+	return 0;
+}
+
 static int
 pl330_probe(struct amba_device *adev, const struct amba_id *id)
 {
@@ -2975,6 +3001,7 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
 	pd->device_prep_slave_sg = pl330_prep_slave_sg;
 	pd->device_control = pl330_control;
 	pd->device_issue_pending = pl330_issue_pending;
+	pd->device_slave_caps = pl330_dma_device_slave_caps;
 
 	ret = dma_async_device_register(pd);
 	if (ret) {
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index c271608e862e..13ac4f553227 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -370,6 +370,33 @@ struct dma_slave_config {
 	unsigned int slave_id;
 };
 
+/* struct dma_slave_caps - expose capabilities of a slave channel only
+ *
+ * @src_addr_widths: bit mask of src addr widths the channel supports
+ * @dstn_addr_widths: bit mask of dstn addr widths the channel supports
+ * @directions: bit mask of slave direction the channel supported
+ * 	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
+ * @cmd_pause: true, if pause and thereby resume is supported
+ * @cmd_terminate: true, if terminate cmd is supported
+ *
+ * @max_sg_nr: maximum number of SG segments supported
+ * 	0 for no maximum
+ * @max_sg_len: maximum length of a SG segment supported
+ * 	0 for no maximum
+ */
+struct dma_slave_caps {
+	u32 src_addr_widths;
+	u32 dstn_addr_widths;
+	u32 directions;
+	bool cmd_pause;
+	bool cmd_terminate;
+
+	u32 max_sg_nr;
+	u32 max_sg_len;
+};
+
 static inline const char *dma_chan_name(struct dma_chan *chan)
 {
 	return dev_name(&chan->dev->device);
@@ -532,6 +559,7 @@ 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_caps: return the slave channel capabilities
  */
 struct dma_device {
 
@@ -597,6 +625,7 @@ struct dma_device {
 					    dma_cookie_t cookie,
 					    struct dma_tx_state *txstate);
 	void (*device_issue_pending)(struct dma_chan *chan);
+	int (*device_slave_caps)(struct dma_chan *chan, struct dma_slave_caps *caps);
 };
 
 static inline int dmaengine_device_control(struct dma_chan *chan,
@@ -670,6 +699,21 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_interleaved_dma(
 	return chan->device->device_prep_interleaved_dma(chan, xt, flags);
 }
 
+static inline int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
+{
+	if (!chan || !caps)
+		return -EINVAL;
+
+	/* check if the channel supports slave transactions */
+	if (!test_bit(DMA_SLAVE, chan->device->cap_mask.bits))
+		return -ENXIO;
+
+	if (chan->device->device_slave_caps)
+		return chan->device->device_slave_caps(chan, caps);
+
+	return -ENXIO;
+}
+
 static inline int dmaengine_terminate_all(struct dma_chan *chan)
 {
 	return dmaengine_device_control(chan, DMA_TERMINATE_ALL, 0);