soc: qcom: ipa: GSI transactions

This patch implements GSI transactions.  A GSI transaction is a
structure that represents a single request (consisting of one or
more TREs) sent to the GSI hardware.  The last TRE in a transaction
includes a flag requesting that the GSI interrupt the AP to notify
that it has completed.

TREs are executed and completed strictly in order.  For this reason,
the completion of a single TRE implies that all previous TREs (in
particular all of those "earlier" in a transaction) have completed.

Whenever there is a need to send a request (a set of TREs) to the
IPA, a GSI transaction is allocated, specifying the number of TREs
that will be required.  Details of the request (e.g. transfer offsets
and length) are represented by in a Linux scatterlist array that is
incorporated in the transaction structure.

Once all commands (TREs) are added to a transaction it is committed.
When the hardware signals that the request has completed, a callback
function allows for cleanup or followup activity to be performed
before the transaction is freed.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/gsi_trans.h

+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2019-2020 Linaro Ltd.
+ */
+#ifndef _GSI_TRANS_H_
+#define _GSI_TRANS_H_
+
+#include <linux/types.h>
+#include <linux/refcount.h>
+#include <linux/completion.h>
+#include <linux/dma-direction.h>
+
+#include "ipa_cmd.h"
+
+struct scatterlist;
+struct device;
+struct sk_buff;
+
+struct gsi;
+struct gsi_trans;
+struct gsi_trans_pool;
+
+/**
+ * struct gsi_trans - a GSI transaction
+ *
+ * Most fields in this structure for internal use by the transaction core code:
+ * @links:	Links for channel transaction lists by state
+ * @gsi:	GSI pointer
+ * @channel_id: Channel number transaction is associated with
+ * @cancelled:	If set by the core code, transaction was cancelled
+ * @tre_count:	Number of TREs reserved for this transaction
+ * @used:	Number of TREs *used* (could be less than tre_count)
+ * @len:	Total # of transfer bytes represented in sgl[] (set by core)
+ * @data:	Preserved but not touched by the core transaction code
+ * @sgl:	An array of scatter/gather entries managed by core code
+ * @info:	Array of command information structures (command channel)
+ * @direction:	DMA transfer direction (DMA_NONE for commands)
+ * @refcount:	Reference count used for destruction
+ * @completion:	Completed when the transaction completes
+ * @byte_count:	TX channel byte count recorded when transaction committed
+ * @trans_count: Channel transaction count when committed (for BQL accounting)
+ *
+ * The size used for some fields in this structure were chosen to ensure
+ * the full structure size is no larger than 128 bytes.
+ */
+struct gsi_trans {
+	struct list_head links;		/* gsi_channel lists */
+
+	struct gsi *gsi;
+	u8 channel_id;
+
+	bool cancelled;			/* true if transaction was cancelled */
+
+	u8 tre_count;			/* # TREs requested */
+	u8 used;			/* # entries used in sgl[] */
+	u32 len;			/* total # bytes across sgl[] */
+
+	void *data;
+	struct scatterlist *sgl;
+	struct ipa_cmd_info *info;	/* array of entries, or null */
+	enum dma_data_direction direction;
+
+	refcount_t refcount;
+	struct completion completion;
+
+	u64 byte_count;			/* channel byte_count when committed */
+	u64 trans_count;		/* channel trans_count when committed */
+};
+
+/**
+ * gsi_trans_pool_init() - Initialize a pool of structures for transactions
+ * @gsi:	GSI pointer
+ * @size:	Size of elements in the pool
+ * @count:	Minimum number of elements in the pool
+ * @max_alloc:	Maximum number of elements allocated at a time from pool
+ *
+ * @Return:	0 if successful, or a negative error code
+ */
+int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
+			u32 max_alloc);
+
+/**
+ * gsi_trans_pool_alloc() - Allocate one or more elements from a pool
+ * @pool:	Pool pointer
+ * @count:	Number of elements to allocate from the pool
+ *
+ * @Return:	Virtual address of element(s) allocated from the pool
+ */
+void *gsi_trans_pool_alloc(struct gsi_trans_pool *pool, u32 count);
+
+/**
+ * gsi_trans_pool_exit() - Inverse of gsi_trans_pool_init()
+ * @pool:	Pool pointer
+ */
+void gsi_trans_pool_exit(struct gsi_trans_pool *pool);
+
+/**
+ * gsi_trans_pool_init_dma() - Initialize a pool of DMA-able structures
+ * @dev:	Device used for DMA
+ * @pool:	Pool pointer
+ * @size:	Size of elements in the pool
+ * @count:	Minimum number of elements in the pool
+ * @max_alloc:	Maximum number of elements allocated at a time from pool
+ *
+ * @Return:	0 if successful, or a negative error code
+ *
+ * Structures in this pool reside in DMA-coherent memory.
+ */
+int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool,
+			    size_t size, u32 count, u32 max_alloc);
+
+/**
+ * gsi_trans_pool_alloc_dma() - Allocate an element from a DMA pool
+ * @pool:	DMA pool pointer
+ * @addr:	DMA address "handle" associated with the allocation
+ *
+ * @Return:	Virtual address of element allocated from the pool
+ *
+ * Only one element at a time may be allocated from a DMA pool.
+ */
+void *gsi_trans_pool_alloc_dma(struct gsi_trans_pool *pool, dma_addr_t *addr);
+
+/**
+ * gsi_trans_pool_exit() - Inverse of gsi_trans_pool_init()
+ * @pool:	Pool pointer
+ */
+void gsi_trans_pool_exit_dma(struct device *dev, struct gsi_trans_pool *pool);
+
+/**
+ * gsi_channel_trans_alloc() - Allocate a GSI transaction on a channel
+ * @gsi:	GSI pointer
+ * @channel_id:	Channel the transaction is associated with
+ * @tre_count:	Number of elements in the transaction
+ * @direction:	DMA direction for entire SGL (or DMA_NONE)
+ *
+ * @Return:	A GSI transaction structure, or a null pointer if all
+ *		available transactions are in use
+ */
+struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
+					  u32 tre_count,
+					  enum dma_data_direction direction);
+
+/**
+ * gsi_trans_free() - Free a previously-allocated GSI transaction
+ * @trans:	Transaction to be freed
+ */
+void gsi_trans_free(struct gsi_trans *trans);
+
+/**
+ * gsi_trans_cmd_add() - Add an immediate command to a transaction
+ * @trans:	Transaction
+ * @buf:	Buffer pointer for command payload
+ * @size:	Number of bytes in buffer
+ * @addr:	DMA address for payload
+ * @direction:	Direction of DMA transfer (or DMA_NONE if none required)
+ * @opcode:	IPA immediate command opcode
+ */
+void gsi_trans_cmd_add(struct gsi_trans *trans, void *buf, u32 size,
+		       dma_addr_t addr, enum dma_data_direction direction,
+		       enum ipa_cmd_opcode opcode);
+
+/**
+ * gsi_trans_page_add() - Add a page transfer to a transaction
+ * @trans:	Transaction
+ * @page:	Page pointer
+ * @size:	Number of bytes (starting at offset) to transfer
+ * @offset:	Offset within page for start of transfer
+ */
+int gsi_trans_page_add(struct gsi_trans *trans, struct page *page, u32 size,
+		       u32 offset);
+
+/**
+ * gsi_trans_skb_add() - Add a socket transfer to a transaction
+ * @trans:	Transaction
+ * @skb:	Socket buffer for transfer (outbound)
+ *
+ * @Return:	0, or -EMSGSIZE if socket data won't fit in transaction.
+ */
+int gsi_trans_skb_add(struct gsi_trans *trans, struct sk_buff *skb);
+
+/**
+ * gsi_trans_commit() - Commit a GSI transaction
+ * @trans:	Transaction to commit
+ * @ring_db:	Whether to tell the hardware about these queued transfers
+ */
+void gsi_trans_commit(struct gsi_trans *trans, bool ring_db);
+
+/**
+ * gsi_trans_commit_wait() - Commit a GSI transaction and wait for it
+ *			     to complete
+ * @trans:	Transaction to commit
+ */
+void gsi_trans_commit_wait(struct gsi_trans *trans);
+
+/**
+ * gsi_trans_commit_wait_timeout() - Commit a GSI transaction and wait for
+ *				     it to complete, with timeout
+ * @trans:	Transaction to commit
+ * @timeout:	Timeout period (in milliseconds)
+ */
+int gsi_trans_commit_wait_timeout(struct gsi_trans *trans,
+				  unsigned long timeout);
+
+/**
+ * gsi_trans_read_byte() - Issue a single byte read TRE on a channel
+ * @gsi:	GSI pointer
+ * @channel_id:	Channel on which to read a byte
+ * @addr:	DMA address into which to transfer the one byte
+ *
+ * This is not a transaction operation at all.  It's defined here because
+ * it needs to be done in coordination with other transaction activity.
+ */
+int gsi_trans_read_byte(struct gsi *gsi, u32 channel_id, dma_addr_t addr);
+
+/**
+ * gsi_trans_read_byte_done() - Clean up after a single byte read TRE
+ * @gsi:	GSI pointer
+ * @channel_id:	Channel on which byte was read
+ *
+ * This function needs to be called to signal that the work related
+ * to reading a byte initiated by gsi_trans_read_byte() is complete.
+ */
+void gsi_trans_read_byte_done(struct gsi *gsi, u32 channel_id);
+
+#endif /* _GSI_TRANS_H_ */