ARM: tegra: add IVC protocol implementation

IVC (Inter-VM Communication) protocol is a Tegra-specific IPC (Inter
Processor Communication) framework. Within the context of U-Boot, it is
typically used for communication between the main CPU and various
auxiliary processors. In particular, it will be used to communicate with
the BPMP (Boot and Power Management Processor) on Tegra186 in order to
manipulate clocks and reset signals.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 179 insertions, 0 deletions

diff --git a/arch/arm/include/asm/arch-tegra/ivc.h b/arch/arm/include/asm/arch-tegra/ivc.h
new file mode 100644
index 0000000..7f2287a
--- /dev/null
+++ b/arch/arm/include/asm/arch-tegra/ivc.h
@@ -0,0 +1,179 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#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