Introduce mhi_get_no_free_descriptors() API to return number
of TREs available to queue buffer. MHI clients can use this
API to know before hand if ring is full without calling queue
API.
Signed-off-by: Hemant Kumar <hemantk@xxxxxxxxxxxxxx>
---
drivers/bus/mhi/core/main.c | 12 ++++++++++++
include/linux/mhi.h | 9 +++++++++
2 files changed, 21 insertions(+)
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index feafc4d..cd1c4da 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -294,6 +294,18 @@ int mhi_destroy_device(struct device *dev, void *data)
return 0;
}
+int mhi_get_no_free_descriptors(struct mhi_device *mhi_dev,
+ enum dma_data_direction dir)
+{
+ struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+ struct mhi_chan *mhi_chan = (dir == DMA_TO_DEVICE) ?
+ mhi_dev->ul_chan : mhi_dev->dl_chan;
+ struct mhi_ring *tre_ring = &mhi_chan->tre_ring;
+
+ return get_nr_avail_ring_elements(mhi_cntrl, tre_ring);
+}
+EXPORT_SYMBOL_GPL(mhi_get_no_free_descriptors);
+
void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
{
struct mhi_driver *mhi_drv;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 24a3dff..ac44326 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -620,6 +620,15 @@ void mhi_set_mhi_state(struct mhi_controller *mhi_cntrl,
void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason);
/**
+ * mhi_get_no_free_descriptors - Get transfer ring length
+ * Get # of TD available to queue buffers
+ * @mhi_dev: Device associated with the channels
+ * @dir: Direction of the channel
+ */
+int mhi_get_no_free_descriptors(struct mhi_device *mhi_dev,
+ enum dma_data_direction dir);
+
+/**
* mhi_prepare_for_power_up - Do pre-initialization before power up.
* This is optional, call this before power up if
* the controller does not want bus framework to
--
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