path: root/drivers/rpmsg/virtio_rpmsg_bus.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Virtio-based remote processor messaging bus
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Copyright (C) 2011 Google, Inc.
 *
 * Ohad Ben-Cohen <ohad@wizery.com>
 * Brian Swetland <swetland@google.com>
 */

#define pr_fmt(fmt) "%s: " fmt, __func__

#include <linux/dma-mapping.h>
#include <linux/idr.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/rpmsg.h>
#include <linux/rpmsg/byteorder.h>
#include <linux/rpmsg/ns.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/virtio.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_config.h>
#include <linux/wait.h>

#include "rpmsg_internal.h"

/**
 * struct virtproc_info - virtual remote processor state
 * @vdev:	the virtio device
 * @rvq:	rx virtqueue
 * @svq:	tx virtqueue
 * @rbufs:	kernel address of rx buffers
 * @sbufs:	kernel address of tx buffers
 * @num_bufs:	total number of buffers for rx and tx
 * @buf_size:   size of one rx or tx buffer
 * @last_sbuf:	index of last tx buffer used
 * @bufs_dma:	dma base addr of the buffers
 * @tx_lock:	protects svq, sbufs and sleepers, to allow concurrent senders.
 *		sending a message might require waking up a dozing remote
 *		processor, which involves sleeping, hence the mutex.
 * @endpoints:	idr of local endpoints, allows fast retrieval
 * @endpoints_lock: lock of the endpoints set
 * @sendq:	wait queue of sending contexts waiting for a tx buffers
 * @sleepers:	number of senders that are waiting for a tx buffer
 *
 * This structure stores the rpmsg state of a given virtio remote processor
 * device (there might be several virtio proc devices for each physical
 * remote processor).
 */
struct virtproc_info {
	struct virtio_device *vdev;
	struct virtqueue *rvq, *svq;
	void *rbufs, *sbufs;
	unsigned int num_bufs;
	unsigned int buf_size;
	int last_sbuf;
	dma_addr_t bufs_dma;
	struct mutex tx_lock;
	struct idr endpoints;
	struct mutex endpoints_lock;
	wait_queue_head_t sendq;
	atomic_t sleepers;
};

/* The feature bitmap for virtio rpmsg */
#define VIRTIO_RPMSG_F_NS	0 /* RP supports name service notifications */

/**
 * struct rpmsg_hdr - common header for all rpmsg messages
 * @src: source address
 * @dst: destination address
 * @reserved: reserved for future use
 * @len: length of payload (in bytes)
 * @flags: message flags
 * @data: @len bytes of message payload data
 *
 * Every message sent(/received) on the rpmsg bus begins with this header.
 */
struct rpmsg_hdr {
	__rpmsg32 src;
	__rpmsg32 dst;
	__rpmsg32 reserved;
	__rpmsg16 len;
	__rpmsg16 flags;
	u8 data[];
} __packed;


/**
 * struct virtio_rpmsg_channel - rpmsg channel descriptor
 * @rpdev: the rpmsg channel device
 * @vrp: the virtio remote processor device this channel belongs to
 *
 * This structure stores the channel that links the rpmsg device to the virtio
 * remote processor device.
 */
struct virtio_rpmsg_channel {
	struct rpmsg_device rpdev;

	struct virtproc_info *vrp;
};

#define to_virtio_rpmsg_channel(_rpdev) \
	container_of(_rpdev, struct virtio_rpmsg_channel, rpdev)

/*
 * We're allocating buffers of 512 bytes each for communications. The
 * number of buffers will be computed from the number of buffers supported
 * by the vring, upto a maximum of 512 buffers (256 in each direction).
 *
 * Each buffer will have 16 bytes for the msg header and 496 bytes for
 * the payload.
 *
 * This will utilize a maximum total space of 256KB for the buffers.
 *
 * We might also want to add support for user-provided buffers in time.
 * This will allow bigger buffer size flexibility, and can also be used
 * to achieve zero-copy messaging.
 *
 * Note that these numbers are purely a decision of this driver - we
 * can change this without changing anything in the firmware of the remote
 * processor.
 */
#define MAX_RPMSG_NUM_BUFS	(512)
#define MAX_RPMSG_BUF_SIZE	(512)

/*
 * Local addresses are dynamically allocated on-demand.
 * We do not dynamically assign addresses from the low 1024 range,
 * in order to reserve that address range for predefined services.
 */
#define RPMSG_RESERVED_ADDRESSES	(1024)

static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len);
static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
			       u32 dst);
static int virtio_rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src,
					u32 dst, void *data, int len);
static int virtio_rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len);
static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data,
				  int len, u32 dst);
static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
					   u32 dst, void *data, int len);
static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept);
static struct rpmsg_device *__rpmsg_create_channel(struct virtproc_info *vrp,
						   struct rpmsg_channel_info *chinfo);

static const struct rpmsg_endpoint_ops virtio_endpoint_ops = {
	.destroy_ept = virtio_rpmsg_destroy_ept,
	.send = virtio_rpmsg_send,
	.sendto = virtio_rpmsg_sendto,
	.send_offchannel = virtio_rpmsg_send_offchannel,
	.trysend = virtio_rpmsg_trysend,
	.trysendto = virtio_rpmsg_trysendto,
	.trysend_offchannel = virtio_rpmsg_trysend_offchannel,
	.get_mtu<