path: root/drivers/rpmsg/qcom_smd.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2015, Sony Mobile Communications AB.
 * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
 */

#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mailbox_client.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/sched.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/soc/qcom/smem.h>
#include <linux/wait.h>
#include <linux/rpmsg.h>
#include <linux/rpmsg/qcom_smd.h>

#include "rpmsg_internal.h"

/*
 * The Qualcomm Shared Memory communication solution provides point-to-point
 * channels for clients to send and receive streaming or packet based data.
 *
 * Each channel consists of a control item (channel info) and a ring buffer
 * pair. The channel info carry information related to channel state, flow
 * control and the offsets within the ring buffer.
 *
 * All allocated channels are listed in an allocation table, identifying the
 * pair of items by name, type and remote processor.
 *
 * Upon creating a new channel the remote processor allocates channel info and
 * ring buffer items from the smem heap and populate the allocation table. An
 * interrupt is sent to the other end of the channel and a scan for new
 * channels should be done. A channel never goes away, it will only change
 * state.
 *
 * The remote processor signals it intent for bring up the communication
 * channel by setting the state of its end of the channel to "opening" and
 * sends out an interrupt. We detect this change and register a smd device to
 * consume the channel. Upon finding a consumer we finish the handshake and the
 * channel is up.
 *
 * Upon closing a channel, the remote processor will update the state of its
 * end of the channel and signal us, we will then unregister any attached
 * device and close our end of the channel.
 *
 * Devices attached to a channel can use the qcom_smd_send function to push
 * data to the channel, this is done by copying the data into the tx ring
 * buffer, updating the pointers in the channel info and signaling the remote
 * processor.
 *
 * The remote processor does the equivalent when it transfer data and upon
 * receiving the interrupt we check the channel info for new data and delivers
 * this to the attached device. If the device is not ready to receive the data
 * we leave it in the ring buffer for now.
 */

struct smd_channel_info;
struct smd_channel_info_pair;
struct smd_channel_info_word;
struct smd_channel_info_word_pair;

static const struct rpmsg_endpoint_ops qcom_smd_endpoint_ops;

#define SMD_ALLOC_TBL_COUNT	2
#define SMD_ALLOC_TBL_SIZE	64

/*
 * This lists the various smem heap items relevant for the allocation table and
 * smd channel entries.
 */
static const struct {
	unsigned alloc_tbl_id;
	unsigned info_base_id;
	unsigned fifo_base_id;
} smem_items[SMD_ALLOC_TBL_COUNT] = {
	{
		.alloc_tbl_id = 13,
		.info_base_id = 14,
		.fifo_base_id = 338
	},
	{
		.alloc_tbl_id = 266,
		.info_base_id = 138,
		.fifo_base_id = 202,
	},
};

/**
 * struct qcom_smd_edge - representing a remote processor
 * @dev:		device associated with this edge
 * @name:		name of this edge
 * @of_node:		of_node handle for information related to this edge
 * @edge_id:		identifier of this edge
 * @remote_pid:		identifier of remote processor
 * @irq:		interrupt for signals on this edge
 * @ipc_regmap:		regmap handle holding the outgoing ipc register
 * @ipc_offset:		offset within @ipc_regmap of the register for ipc
 * @ipc_bit:		bit in the register at @ipc_offset of @ipc_regmap
 * @mbox_client:	mailbox client handle
 * @mbox_chan:		apcs ipc mailbox channel handle
 * @channels:		list of all channels detected on this edge
 * @channels_lock:	guard for modifications of @channels
 * @allocated:		array of bitmaps representing already allocated channels
 * @smem_available:	last available amount of smem triggering a channel scan
 * @new_channel_event:	wait queue for new channel events
 * @scan_work:		work item for discovering new channels
 * @state_work:		work item for edge state changes
 */
struct qcom_smd_edge {
	struct device dev;

	const char *name;

	struct device_node *of_node;
	unsigned edge_id;
	unsigned remote_pid;

	int irq;

	struct regmap *ipc_regmap;
	int ipc_offset;
	int ipc_bit;

	struct mbox_client mbox_client;
	struct mbox_chan *mbox_chan;

	struct list_head channels;
	spinlock_t channels_lock;

	DECLARE_BITMAP(allocated[SMD_ALLOC_TBL_COUNT], SMD_ALLOC_TBL_SIZE);

	unsigned smem_available;

	wait_queue_head_t new_channel_event;

	struct work_struct scan_work;
	struct work_struct state_work;
};

/*
 * SMD channel states.
 */
enum smd_channel_state {
	SMD_CHANNEL_CLOSED,
	SMD_CHANNEL_OPENING,
	SMD_CHANNEL_OPENED,
	SMD_CHANNEL_FLUSHING,
	SMD_CHANNEL_CLOSING,
	SMD_CHANNEL_RESET,
	SMD_CHANNEL_RESET_OPENING
};

struct qcom_smd_device {
	struct rpmsg_device rpdev;

	struct qcom_smd_edge *edge;
};

struct qcom_smd_endpoint {
	struct rpmsg_endpoint ept;

	struct qcom_smd_channel *qsch;
};

#define to_smd_device(r)	container_of(r, struct qcom_smd_device, rpdev)
#define to_smd_edge(d)		container_of(d, struct qcom_smd_edge, dev)
#define to_smd_endpoint(e)	container_of