179 lines
5.7 KiB
C
179 lines
5.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2016, NVIDIA CORPORATION.
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*/
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#ifndef _ASM_ARCH_TEGRA_IVC_H
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#define _ASM_ARCH_TEGRA_IVC_H
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#include <common.h>
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/*
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* Tegra IVC is a communication protocol that transfers fixed-size frames
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* bi-directionally and in-order between the local CPU and some remote entity.
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* Communication is via a statically sized and allocated buffer in shared
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* memory and a notification mechanism.
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*
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* This API handles all aspects of the shared memory buffer's metadata, and
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* leaves all aspects of the frame content to the calling code; frames
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* typically contain some higher-level protocol. The notification mechanism is
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* also handled externally to this API, since it can vary from instance to
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* instance.
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*
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* The client model is to first find some free (for TX) or filled (for RX)
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* frame, process that frame's memory buffer (fill or read it), and then
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* inform the protocol that the frame has been filled/read, i.e. advance the
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* write/read pointer. If the channel is full, there may be no available frames
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* to fill/read. In this case, client code may either poll for an available
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* frame, or wait for the remote entity to send a notification to the local
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* CPU.
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*/
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/**
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* struct tegra_ivc - In-memory shared memory layout.
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*
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* This is described in detail in ivc.c.
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*/
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struct tegra_ivc_channel_header;
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/**
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* struct tegra_ivc - Software state of an IVC channel.
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*
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* This state is internal to the IVC code and should not be accessed directly
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* by clients. It is public solely so clients can allocate storage for the
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* structure.
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*/
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struct tegra_ivc {
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/**
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* rx_channel - Pointer to the shared memory region used to receive
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* messages from the remote entity.
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*/
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struct tegra_ivc_channel_header *rx_channel;
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/**
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* tx_channel - Pointer to the shared memory region used to send
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* messages to the remote entity.
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*/
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struct tegra_ivc_channel_header *tx_channel;
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/**
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* r_pos - The position in list of frames in rx_channel that we are
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* reading from.
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*/
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uint32_t r_pos;
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/**
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* w_pos - The position in list of frames in tx_channel that we are
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* writing to.
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*/
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uint32_t w_pos;
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/**
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* nframes - The number of frames allocated (in each direction) in
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* shared memory.
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*/
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uint32_t nframes;
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/**
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* frame_size - The size of each frame in shared memory.
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*/
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uint32_t frame_size;
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/**
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* notify - Function to call to notify the remote processor of a
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* change in channel state.
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*/
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void (*notify)(struct tegra_ivc *);
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};
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/**
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* tegra_ivc_read_get_next_frame - Locate the next frame to receive.
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*
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* Locate the next frame to be received/processed, return the address of the
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* frame, and do not remove it from the queue. Repeated calls to this function
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* will return the same address until tegra_ivc_read_advance() is called.
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*
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* @ivc The IVC channel.
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* @frame Pointer to be filled with the address of the frame to receive.
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*
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* @return 0 if a frame is available, else a negative error code.
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*/
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int tegra_ivc_read_get_next_frame(struct tegra_ivc *ivc, void **frame);
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/**
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* tegra_ivc_read_advance - Advance the read queue.
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*
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* Inform the protocol and remote entity that the frame returned by
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* tegra_ivc_read_get_next_frame() has been processed. The remote end may then
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* re-use it to transmit further data. Subsequent to this function returning,
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* tegra_ivc_read_get_next_frame() will return a different frame.
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*
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* @ivc The IVC channel.
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*
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* @return 0 if OK, else a negative error code.
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*/
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int tegra_ivc_read_advance(struct tegra_ivc *ivc);
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/**
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* tegra_ivc_write_get_next_frame - Locate the next frame to fill for transmit.
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*
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* Locate the next frame to be filled for transmit, return the address of the
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* frame, and do not add it to the queue. Repeated calls to this function
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* will return the same address until tegra_ivc_read_advance() is called.
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*
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* @ivc The IVC channel.
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* @frame Pointer to be filled with the address of the frame to fill.
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*
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* @return 0 if a frame is available, else a negative error code.
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*/
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int tegra_ivc_write_get_next_frame(struct tegra_ivc *ivc, void **frame);
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/**
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* tegra_ivc_write_advance - Advance the write queue.
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*
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* Inform the protocol and remote entity that the frame returned by
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* tegra_ivc_write_get_next_frame() has been filled and should be transmitted.
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* The remote end may then read data from it. Subsequent to this function
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* returning, tegra_ivc_write_get_next_frame() will return a different frame.
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*
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* @ivc The IVC channel.
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*
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* @return 0 if OK, else a negative error code.
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*/
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int tegra_ivc_write_advance(struct tegra_ivc *ivc);
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/**
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* tegra_ivc_channel_notified - handle internal messages
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*
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* This function must be called following every notification.
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*
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* @ivc The IVC channel.
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*
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* @return 0 if the channel is ready for communication, or -EAGAIN if a
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* channel reset is in progress.
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*/
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int tegra_ivc_channel_notified(struct tegra_ivc *ivc);
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/**
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* tegra_ivc_channel_reset - initiates a reset of the shared memory state
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*
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* This function must be called after a channel is initialized but before it
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* is used for communication. The channel will be ready for use when a
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* subsequent call to notify the remote of the channel reset indicates the
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* reset operation is complete.
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*
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* @ivc The IVC channel.
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*/
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void tegra_ivc_channel_reset(struct tegra_ivc *ivc);
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/**
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* tegra_ivc_init - Initialize a channel's software state.
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*
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* @ivc The IVC channel.
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* @rx_base Address of the the RX shared memory buffer.
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* @tx_base Address of the the TX shared memory buffer.
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* @nframes Number of frames in each shared memory buffer.
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* @frame_size Size of each frame.
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*
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* @return 0 if OK, else a negative error code.
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*/
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int tegra_ivc_init(struct tegra_ivc *ivc, ulong rx_base, ulong tx_base,
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uint32_t nframes, uint32_t frame_size,
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void (*notify)(struct tegra_ivc *));
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#endif
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