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bus: mhi: core: Add helper API to return number of free TREs

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Introduce mhi_get_free_desc_count() 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@codeaurora.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1610388462-16322-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
This commit is contained in:
Hemant Kumar 2021-01-11 19:07:40 +01:00 committed by Manivannan Sadhasivam
parent 5c8fe583cc
commit 87baa23e02
2 changed files with 21 additions and 0 deletions
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12
drivers/bus/mhi/core/main.c
View File

@ -260,6 +260,18 @@ int mhi_destroy_device(struct device *dev, void *data)
return 0;
}
int mhi_get_free_desc_count(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_free_desc_count);
void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
{
struct mhi_driver *mhi_drv;

9
include/linux/mhi.h
View File

@ -598,6 +598,15 @@ 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_free_desc_count - 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_free_desc_count(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