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