diff options
Diffstat (limited to 'drivers/rpmsg/virtio_rpmsg_bus.c')
| -rw-r--r-- | drivers/rpmsg/virtio_rpmsg_bus.c | 1082 |
1 files changed, 1082 insertions, 0 deletions
diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c new file mode 100644 index 0000000000..f1af0f6746 --- /dev/null +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -0,0 +1,1082 @@ +// 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 = virtio_rpmsg_get_mtu, +}; + +/** + * rpmsg_sg_init - initialize scatterlist according to cpu address location + * @sg: scatterlist to fill + * @cpu_addr: virtual address of the buffer + * @len: buffer length + * + * An internal function filling scatterlist according to virtual address + * location (in vmalloc or in kernel). + */ +static void +rpmsg_sg_init(struct scatterlist *sg, void *cpu_addr, unsigned int len) +{ + if (is_vmalloc_addr(cpu_addr)) { + sg_init_table(sg, 1); + sg_set_page(sg, vmalloc_to_page(cpu_addr), len, + offset_in_page(cpu_addr)); + } else { + WARN_ON(!virt_addr_valid(cpu_addr)); + sg_init_one(sg, cpu_addr, len); + } +} + +/** + * __ept_release() - deallocate an rpmsg endpoint + * @kref: the ept's reference count + * + * This function deallocates an ept, and is invoked when its @kref refcount + * drops to zero. + * + * Never invoke this function directly! + */ +static void __ept_release(struct kref *kref) +{ + struct rpmsg_endpoint *ept = container_of(kref, struct rpmsg_endpoint, + refcount); + /* + * At this point no one holds a reference to ept anymore, + * so we can directly free it + */ + kfree(ept); +} + +/* for more info, see below documentation of rpmsg_create_ept() */ +static struct rpmsg_endpoint *__rpmsg_create_ept(struct virtproc_info *vrp, + struct rpmsg_device *rpdev, + rpmsg_rx_cb_t cb, + void *priv, u32 addr) +{ + int id_min, id_max, id; + struct rpmsg_endpoint *ept; + struct device *dev = rpdev ? &rpdev->dev : &vrp->vdev->dev; + + ept = kzalloc(sizeof(*ept), GFP_KERNEL); + if (!ept) + return NULL; + + kref_init(&ept->refcount); + mutex_init(&ept->cb_lock); + + ept->rpdev = rpdev; + ept->cb = cb; + ept->priv = priv; + ept->ops = &virtio_endpoint_ops; + + /* do we need to allocate a local address ? */ + if (addr == RPMSG_ADDR_ANY) { + id_min = RPMSG_RESERVED_ADDRESSES; + id_max = 0; + } else { + id_min = addr; + id_max = addr + 1; + } + + mutex_lock(&vrp->endpoints_lock); + + /* bind the endpoint to an rpmsg address (and allocate one if needed) */ + id = idr_alloc(&vrp->endpoints, ept, id_min, id_max, GFP_KERNEL); + if (id < 0) { + dev_err(dev, "idr_alloc failed: %d\n", id); + goto free_ept; + } + ept->addr = id; + + mutex_unlock(&vrp->endpoints_lock); + + return ept; + +free_ept: + mutex_unlock(&vrp->endpoints_lock); + kref_put(&ept->refcount, __ept_release); + return NULL; +} + +static struct rpmsg_device *virtio_rpmsg_create_channel(struct rpmsg_device *rpdev, + struct rpmsg_channel_info *chinfo) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + struct virtproc_info *vrp = vch->vrp; + + return __rpmsg_create_channel(vrp, chinfo); +} + +static int virtio_rpmsg_release_channel(struct rpmsg_device *rpdev, + struct rpmsg_channel_info *chinfo) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + struct virtproc_info *vrp = vch->vrp; + + return rpmsg_unregister_device(&vrp->vdev->dev, chinfo); +} + +static struct rpmsg_endpoint *virtio_rpmsg_create_ept(struct rpmsg_device *rpdev, + rpmsg_rx_cb_t cb, + void *priv, + struct rpmsg_channel_info chinfo) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + + return __rpmsg_create_ept(vch->vrp, rpdev, cb, priv, chinfo.src); +} + +/** + * __rpmsg_destroy_ept() - destroy an existing rpmsg endpoint + * @vrp: virtproc which owns this ept + * @ept: endpoing to destroy + * + * An internal function which destroy an ept without assuming it is + * bound to an rpmsg channel. This is needed for handling the internal + * name service endpoint, which isn't bound to an rpmsg channel. + * See also __rpmsg_create_ept(). + */ +static void +__rpmsg_destroy_ept(struct virtproc_info *vrp, struct rpmsg_endpoint *ept) +{ + /* make sure new inbound messages can't find this ept anymore */ + mutex_lock(&vrp->endpoints_lock); + idr_remove(&vrp->endpoints, ept->addr); + mutex_unlock(&vrp->endpoints_lock); + + /* make sure in-flight inbound messages won't invoke cb anymore */ + mutex_lock(&ept->cb_lock); + ept->cb = NULL; + mutex_unlock(&ept->cb_lock); + + kref_put(&ept->refcount, __ept_release); +} + +static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(ept->rpdev); + + __rpmsg_destroy_ept(vch->vrp, ept); +} + +static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + struct virtproc_info *vrp = vch->vrp; + struct device *dev = &rpdev->dev; + int err = 0; + + /* need to tell remote processor's name service about this channel ? */ + if (rpdev->announce && rpdev->ept && + virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) { + struct rpmsg_ns_msg nsm; + + strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE); + nsm.addr = cpu_to_rpmsg32(rpdev, rpdev->ept->addr); + nsm.flags = cpu_to_rpmsg32(rpdev, RPMSG_NS_CREATE); + + err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR); + if (err) + dev_err(dev, "failed to announce service %d\n", err); + } + + return err; +} + +static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + struct virtproc_info *vrp = vch->vrp; + struct device *dev = &rpdev->dev; + int err = 0; + + /* tell remote processor's name service we're removing this channel */ + if (rpdev->announce && rpdev->ept && + virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) { + struct rpmsg_ns_msg nsm; + + strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE); + nsm.addr = cpu_to_rpmsg32(rpdev, rpdev->ept->addr); + nsm.flags = cpu_to_rpmsg32(rpdev, RPMSG_NS_DESTROY); + + err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR); + if (err) + dev_err(dev, "failed to announce service %d\n", err); + } + + return err; +} + +static const struct rpmsg_device_ops virtio_rpmsg_ops = { + .create_channel = virtio_rpmsg_create_channel, + .release_channel = virtio_rpmsg_release_channel, + .create_ept = virtio_rpmsg_create_ept, + .announce_create = virtio_rpmsg_announce_create, + .announce_destroy = virtio_rpmsg_announce_destroy, +}; + +static void virtio_rpmsg_release_device(struct device *dev) +{ + struct rpmsg_device *rpdev = to_rpmsg_device(dev); + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + + kfree(rpdev->driver_override); + kfree(vch); +} + +/* + * create an rpmsg channel using its name and address info. + * this function will be used to create both static and dynamic + * channels. + */ +static struct rpmsg_device *__rpmsg_create_channel(struct virtproc_info *vrp, + struct rpmsg_channel_info *chinfo) +{ + struct virtio_rpmsg_channel *vch; + struct rpmsg_device *rpdev; + struct device *tmp, *dev = &vrp->vdev->dev; + int ret; + + /* make sure a similar channel doesn't already exist */ + tmp = rpmsg_find_device(dev, chinfo); + if (tmp) { + /* decrement the matched device's refcount back */ + put_device(tmp); + dev_err(dev, "channel %s:%x:%x already exist\n", + chinfo->name, chinfo->src, chinfo->dst); + return NULL; + } + + vch = kzalloc(sizeof(*vch), GFP_KERNEL); + if (!vch) + return NULL; + + /* Link the channel to our vrp */ + vch->vrp = vrp; + + /* Assign public information to the rpmsg_device */ + rpdev = &vch->rpdev; + rpdev->src = chinfo->src; + rpdev->dst = chinfo->dst; + rpdev->ops = &virtio_rpmsg_ops; + rpdev->little_endian = virtio_is_little_endian(vrp->vdev); + + /* + * rpmsg server channels has predefined local address (for now), + * and their existence needs to be announced remotely + */ + rpdev->announce = rpdev->src != RPMSG_ADDR_ANY; + + strncpy(rpdev->id.name, chinfo->name, RPMSG_NAME_SIZE); + + rpdev->dev.parent = &vrp->vdev->dev; + rpdev->dev.release = virtio_rpmsg_release_device; + ret = rpmsg_register_device(rpdev); + if (ret) + return NULL; + + return rpdev; +} + +/* super simple buffer "allocator" that is just enough for now */ +static void *get_a_tx_buf(struct virtproc_info *vrp) +{ + unsigned int len; + void *ret; + + /* support multiple concurrent senders */ + mutex_lock(&vrp->tx_lock); + + /* + * either pick the next unused tx buffer + * (half of our buffers are used for sending messages) + */ + if (vrp->last_sbuf < vrp->num_bufs / 2) + ret = vrp->sbufs + vrp->buf_size * vrp->last_sbuf++; + /* or recycle a used one */ + else + ret = virtqueue_get_buf(vrp->svq, &len); + + mutex_unlock(&vrp->tx_lock); + + return ret; +} + +/** + * rpmsg_upref_sleepers() - enable "tx-complete" interrupts, if needed + * @vrp: virtual remote processor state + * + * This function is called before a sender is blocked, waiting for + * a tx buffer to become available. + * + * If we already have blocking senders, this function merely increases + * the "sleepers" reference count, and exits. + * + * Otherwise, if this is the first sender to block, we also enable + * virtio's tx callbacks, so we'd be immediately notified when a tx + * buffer is consumed (we rely on virtio's tx callback in order + * to wake up sleeping senders as soon as a tx buffer is used by the + * remote processor). + */ +static void rpmsg_upref_sleepers(struct virtproc_info *vrp) +{ + /* support multiple concurrent senders */ + mutex_lock(&vrp->tx_lock); + + /* are we the first sleeping context waiting for tx buffers ? */ + if (atomic_inc_return(&vrp->sleepers) == 1) + /* enable "tx-complete" interrupts before dozing off */ + virtqueue_enable_cb(vrp->svq); + + mutex_unlock(&vrp->tx_lock); +} + +/** + * rpmsg_downref_sleepers() - disable "tx-complete" interrupts, if needed + * @vrp: virtual remote processor state + * + * This function is called after a sender, that waited for a tx buffer + * to become available, is unblocked. + * + * If we still have blocking senders, this function merely decreases + * the "sleepers" reference count, and exits. + * + * Otherwise, if there are no more blocking senders, we also disable + * virtio's tx callbacks, to avoid the overhead incurred with handling + * those (now redundant) interrupts. + */ +static void rpmsg_downref_sleepers(struct virtproc_info *vrp) +{ + /* support multiple concurrent senders */ + mutex_lock(&vrp->tx_lock); + + /* are we the last sleeping context waiting for tx buffers ? */ + if (atomic_dec_and_test(&vrp->sleepers)) + /* disable "tx-complete" interrupts */ + virtqueue_disable_cb(vrp->svq); + + mutex_unlock(&vrp->tx_lock); +} + +/** + * rpmsg_send_offchannel_raw() - send a message across to the remote processor + * @rpdev: the rpmsg channel + * @src: source address + * @dst: destination address + * @data: payload of message + * @len: length of payload + * @wait: indicates whether caller should block in case no TX buffers available + * + * This function is the base implementation for all of the rpmsg sending API. + * + * It will send @data of length @len to @dst, and say it's from @src. The + * message will be sent to the remote processor which the @rpdev channel + * belongs to. + * + * The message is sent using one of the TX buffers that are available for + * communication with this remote processor. + * + * If @wait is true, the caller will be blocked until either a TX buffer is + * available, or 15 seconds elapses (we don't want callers to + * sleep indefinitely due to misbehaving remote processors), and in that + * case -ERESTARTSYS is returned. The number '15' itself was picked + * arbitrarily; there's little point in asking drivers to provide a timeout + * value themselves. + * + * Otherwise, if @wait is false, and there are no TX buffers available, + * the function will immediately fail, and -ENOMEM will be returned. + * + * Normally drivers shouldn't use this function directly; instead, drivers + * should use the appropriate rpmsg_{try}send{to, _offchannel} API + * (see include/linux/rpmsg.h). + * + * Return: 0 on success and an appropriate error value on failure. + */ +static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev, + u32 src, u32 dst, + void *data, int len, bool wait) +{ + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + struct virtproc_info *vrp = vch->vrp; + struct device *dev = &rpdev->dev; + struct scatterlist sg; + struct rpmsg_hdr *msg; + int err; + + /* bcasting isn't allowed */ + if (src == RPMSG_ADDR_ANY || dst == RPMSG_ADDR_ANY) { + dev_err(dev, "invalid addr (src 0x%x, dst 0x%x)\n", src, dst); + return -EINVAL; + } + + /* + * We currently use fixed-sized buffers, and therefore the payload + * length is limited. + * + * One of the possible improvements here is either to support + * user-provided buffers (and then we can also support zero-copy + * messaging), or to improve the buffer allocator, to support + * variable-length buffer sizes. + */ + if (len > vrp->buf_size - sizeof(struct rpmsg_hdr)) { + dev_err(dev, "message is too big (%d)\n", len); + return -EMSGSIZE; + } + + /* grab a buffer */ + msg = get_a_tx_buf(vrp); + if (!msg && !wait) + return -ENOMEM; + + /* no free buffer ? wait for one (but bail after 15 seconds) */ + while (!msg) { + /* enable "tx-complete" interrupts, if not already enabled */ + rpmsg_upref_sleepers(vrp); + + /* + * sleep until a free buffer is available or 15 secs elapse. + * the timeout period is not configurable because there's + * little point in asking drivers to specify that. + * if later this happens to be required, it'd be easy to add. + */ + err = wait_event_interruptible_timeout(vrp->sendq, + (msg = get_a_tx_buf(vrp)), + msecs_to_jiffies(15000)); + + /* disable "tx-complete" interrupts if we're the last sleeper */ + rpmsg_downref_sleepers(vrp); + + /* timeout ? */ + if (!err) { + dev_err(dev, "timeout waiting for a tx buffer\n"); + return -ERESTARTSYS; + } + } + + msg->len = cpu_to_rpmsg16(rpdev, len); + msg->flags = 0; + msg->src = cpu_to_rpmsg32(rpdev, src); + msg->dst = cpu_to_rpmsg32(rpdev, dst); + msg->reserved = 0; + memcpy(msg->data, data, len); + + dev_dbg(dev, "TX From 0x%x, To 0x%x, Len %d, Flags %d, Reserved %d\n", + src, dst, len, msg->flags, msg->reserved); +#if defined(CONFIG_DYNAMIC_DEBUG) + dynamic_hex_dump("rpmsg_virtio TX: ", DUMP_PREFIX_NONE, 16, 1, + msg, sizeof(*msg) + len, true); +#endif + + rpmsg_sg_init(&sg, msg, sizeof(*msg) + len); + + mutex_lock(&vrp->tx_lock); + + /* add message to the remote processor's virtqueue */ + err = virtqueue_add_outbuf(vrp->svq, &sg, 1, msg, GFP_KERNEL); + if (err) { + /* + * need to reclaim the buffer here, otherwise it's lost + * (memory won't leak, but rpmsg won't use it again for TX). + * this will wait for a buffer management overhaul. + */ + dev_err(dev, "virtqueue_add_outbuf failed: %d\n", err); + goto out; + } + + /* tell the remote processor it has a pending message to read */ + virtqueue_kick(vrp->svq); +out: + mutex_unlock(&vrp->tx_lock); + return err; +} + +static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len) +{ + struct rpmsg_device *rpdev = ept->rpdev; + u32 src = ept->addr, dst = rpdev->dst; + + return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true); +} + +static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len, + u32 dst) +{ + struct rpmsg_device *rpdev = ept->rpdev; + u32 src = ept->addr; + + return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true); +} + +static int virtio_rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src, + u32 dst, void *data, int len) +{ + struct rpmsg_device *rpdev = ept->rpdev; + + return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true); +} + +static int virtio_rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len) +{ + struct rpmsg_device *rpdev = ept->rpdev; + u32 src = ept->addr, dst = rpdev->dst; + + return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false); +} + +static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data, + int len, u32 dst) +{ + struct rpmsg_device *rpdev = ept->rpdev; + u32 src = ept->addr; + + return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false); +} + +static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, + u32 dst, void *data, int len) +{ + struct rpmsg_device *rpdev = ept->rpdev; + + return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false); +} + +static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept) +{ + struct rpmsg_device *rpdev = ept->rpdev; + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + + return vch->vrp->buf_size - sizeof(struct rpmsg_hdr); +} + +static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev, + struct rpmsg_hdr *msg, unsigned int len) +{ + struct rpmsg_endpoint *ept; + struct scatterlist sg; + bool little_endian = virtio_is_little_endian(vrp->vdev); + unsigned int msg_len = __rpmsg16_to_cpu(little_endian, msg->len); + int err; + + dev_dbg(dev, "From: 0x%x, To: 0x%x, Len: %d, Flags: %d, Reserved: %d\n", + __rpmsg32_to_cpu(little_endian, msg->src), + __rpmsg32_to_cpu(little_endian, msg->dst), msg_len, + __rpmsg16_to_cpu(little_endian, msg->flags), + __rpmsg32_to_cpu(little_endian, msg->reserved)); +#if defined(CONFIG_DYNAMIC_DEBUG) + dynamic_hex_dump("rpmsg_virtio RX: ", DUMP_PREFIX_NONE, 16, 1, + msg, sizeof(*msg) + msg_len, true); +#endif + + /* + * We currently use fixed-sized buffers, so trivially sanitize + * the reported payload length. + */ + if (len > vrp->buf_size || + msg_len > (len - sizeof(struct rpmsg_hdr))) { + dev_warn(dev, "inbound msg too big: (%d, %d)\n", len, msg_len); + return -EINVAL; + } + + /* use the dst addr to fetch the callback of the appropriate user */ + mutex_lock(&vrp->endpoints_lock); + + ept = idr_find(&vrp->endpoints, __rpmsg32_to_cpu(little_endian, msg->dst)); + + /* let's make sure no one deallocates ept while we use it */ + if (ept) + kref_get(&ept->refcount); + + mutex_unlock(&vrp->endpoints_lock); + + if (ept) { + /* make sure ept->cb doesn't go away while we use it */ + mutex_lock(&ept->cb_lock); + + if (ept->cb) + ept->cb(ept->rpdev, msg->data, msg_len, ept->priv, + __rpmsg32_to_cpu(little_endian, msg->src)); + + mutex_unlock(&ept->cb_lock); + + /* farewell, ept, we don't need you anymore */ + kref_put(&ept->refcount, __ept_release); + } else + dev_warn_ratelimited(dev, "msg received with no recipient\n"); + + /* publish the real size of the buffer */ + rpmsg_sg_init(&sg, msg, vrp->buf_size); + + /* add the buffer back to the remote processor's virtqueue */ + err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, msg, GFP_KERNEL); + if (err < 0) { + dev_err(dev, "failed to add a virtqueue buffer: %d\n", err); + return err; + } + + return 0; +} + +/* called when an rx buffer is used, and it's time to digest a message */ +static void rpmsg_recv_done(struct virtqueue *rvq) +{ + struct virtproc_info *vrp = rvq->vdev->priv; + struct device *dev = &rvq->vdev->dev; + struct rpmsg_hdr *msg; + unsigned int len, msgs_received = 0; + int err; + + msg = virtqueue_get_buf(rvq, &len); + if (!msg) { + dev_err(dev, "uhm, incoming signal, but no used buffer ?\n"); + return; + } + + while (msg) { + err = rpmsg_recv_single(vrp, dev, msg, len); + if (err) + break; + + msgs_received++; + + msg = virtqueue_get_buf(rvq, &len); + } + + dev_dbg(dev, "Received %u messages\n", msgs_received); + + /* tell the remote processor we added another available rx buffer */ + if (msgs_received) + virtqueue_kick(vrp->rvq); +} + +/* + * This is invoked whenever the remote processor completed processing + * a TX msg we just sent it, and the buffer is put back to the used ring. + * + * Normally, though, we suppress this "tx complete" interrupt in order to + * avoid the incurred overhead. + */ +static void rpmsg_xmit_done(struct virtqueue *svq) +{ + struct virtproc_info *vrp = svq->vdev->priv; + + dev_dbg(&svq->vdev->dev, "%s\n", __func__); + + /* wake up potential senders that are waiting for a tx buffer */ + wake_up_interruptible(&vrp->sendq); +} + +/* + * Called to expose to user a /dev/rpmsg_ctrlX interface allowing to + * create endpoint-to-endpoint communication without associated RPMsg channel. + * The endpoints are rattached to the ctrldev RPMsg device. + */ +static struct rpmsg_device *rpmsg_virtio_add_ctrl_dev(struct virtio_device *vdev) +{ + struct virtproc_info *vrp = vdev->priv; + struct virtio_rpmsg_channel *vch; + struct rpmsg_device *rpdev_ctrl; + int err = 0; + + vch = kzalloc(sizeof(*vch), GFP_KERNEL); + if (!vch) + return ERR_PTR(-ENOMEM); + + /* Link the channel to the vrp */ + vch->vrp = vrp; + + /* Assign public information to the rpmsg_device */ + rpdev_ctrl = &vch->rpdev; + rpdev_ctrl->ops = &virtio_rpmsg_ops; + + rpdev_ctrl->dev.parent = &vrp->vdev->dev; + rpdev_ctrl->dev.release = virtio_rpmsg_release_device; + rpdev_ctrl->little_endian = virtio_is_little_endian(vrp->vdev); + + err = rpmsg_ctrldev_register_device(rpdev_ctrl); + if (err) { + /* vch will be free in virtio_rpmsg_release_device() */ + return ERR_PTR(err); + } + + return rpdev_ctrl; +} + +static void rpmsg_virtio_del_ctrl_dev(struct rpmsg_device *rpdev_ctrl) +{ + if (!rpdev_ctrl) + return; + device_unregister(&rpdev_ctrl->dev); +} + +static int rpmsg_probe(struct virtio_device *vdev) +{ + vq_callback_t *vq_cbs[] = { rpmsg_recv_done, rpmsg_xmit_done }; + static const char * const names[] = { "input", "output" }; + struct virtqueue *vqs[2]; + struct virtproc_info *vrp; + struct virtio_rpmsg_channel *vch = NULL; + struct rpmsg_device *rpdev_ns, *rpdev_ctrl; + void *bufs_va; + int err = 0, i; + size_t total_buf_space; + bool notify; + + vrp = kzalloc(sizeof(*vrp), GFP_KERNEL); + if (!vrp) + return -ENOMEM; + + vrp->vdev = vdev; + + idr_init(&vrp->endpoints); + mutex_init(&vrp->endpoints_lock); + mutex_init(&vrp->tx_lock); + init_waitqueue_head(&vrp->sendq); + + /* We expect two virtqueues, rx and tx (and in this order) */ + err = virtio_find_vqs(vdev, 2, vqs, vq_cbs, names, NULL); + if (err) + goto free_vrp; + + vrp->rvq = vqs[0]; + vrp->svq = vqs[1]; + + /* we expect symmetric tx/rx vrings */ + WARN_ON(virtqueue_get_vring_size(vrp->rvq) != + virtqueue_get_vring_size(vrp->svq)); + + /* we need less buffers if vrings are small */ + if (virtqueue_get_vring_size(vrp->rvq) < MAX_RPMSG_NUM_BUFS / 2) + vrp->num_bufs = virtqueue_get_vring_size(vrp->rvq) * 2; + else + vrp->num_bufs = MAX_RPMSG_NUM_BUFS; + + vrp->buf_size = MAX_RPMSG_BUF_SIZE; + + total_buf_space = vrp->num_bufs * vrp->buf_size; + + /* allocate coherent memory for the buffers */ + bufs_va = dma_alloc_coherent(vdev->dev.parent, + total_buf_space, &vrp->bufs_dma, + GFP_KERNEL); + if (!bufs_va) { + err = -ENOMEM; + goto vqs_del; + } + + dev_dbg(&vdev->dev, "buffers: va %pK, dma %pad\n", + bufs_va, &vrp->bufs_dma); + + /* half of the buffers is dedicated for RX */ + vrp->rbufs = bufs_va; + + /* and half is dedicated for TX */ + vrp->sbufs = bufs_va + total_buf_space / 2; + + /* set up the receive buffers */ + for (i = 0; i < vrp->num_bufs / 2; i++) { + struct scatterlist sg; + void *cpu_addr = vrp->rbufs + i * vrp->buf_size; + + rpmsg_sg_init(&sg, cpu_addr, vrp->buf_size); + + err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, cpu_addr, + GFP_KERNEL); + WARN_ON(err); /* sanity check; this can't really happen */ + } + + /* suppress "tx-complete" interrupts */ + virtqueue_disable_cb(vrp->svq); + + vdev->priv = vrp; + + rpdev_ctrl = rpmsg_virtio_add_ctrl_dev(vdev); + if (IS_ERR(rpdev_ctrl)) { + err = PTR_ERR(rpdev_ctrl); + goto free_coherent; + } + + /* if supported by the remote processor, enable the name service */ + if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_NS)) { + vch = kzalloc(sizeof(*vch), GFP_KERNEL); + if (!vch) { + err = -ENOMEM; + goto free_ctrldev; + } + + /* Link the channel to our vrp */ + vch->vrp = vrp; + + /* Assign public information to the rpmsg_device */ + rpdev_ns = &vch->rpdev; + rpdev_ns->ops = &virtio_rpmsg_ops; + rpdev_ns->little_endian = virtio_is_little_endian(vrp->vdev); + + rpdev_ns->dev.parent = &vrp->vdev->dev; + rpdev_ns->dev.release = virtio_rpmsg_release_device; + + err = rpmsg_ns_register_device(rpdev_ns); + if (err) + /* vch will be free in virtio_rpmsg_release_device() */ + goto free_ctrldev; + } + + /* + * Prepare to kick but don't notify yet - we can't do this before + * device is ready. + */ + notify = virtqueue_kick_prepare(vrp->rvq); + + /* From this point on, we can notify and get callbacks. */ + virtio_device_ready(vdev); + + /* tell the remote processor it can start sending messages */ + /* + * this might be concurrent with callbacks, but we are only + * doing notify, not a full kick here, so that's ok. + */ + if (notify) + virtqueue_notify(vrp->rvq); + + dev_info(&vdev->dev, "rpmsg host is online\n"); + + return 0; + +free_ctrldev: + rpmsg_virtio_del_ctrl_dev(rpdev_ctrl); +free_coherent: + dma_free_coherent(vdev->dev.parent, total_buf_space, + bufs_va, vrp->bufs_dma); +vqs_del: + vdev->config->del_vqs(vrp->vdev); +free_vrp: + kfree(vrp); + return err; +} + +static int rpmsg_remove_device(struct device *dev, void *data) +{ + device_unregister(dev); + + return 0; +} + +static void rpmsg_remove(struct virtio_device *vdev) +{ + struct virtproc_info *vrp = vdev->priv; + size_t total_buf_space = vrp->num_bufs * vrp->buf_size; + int ret; + + virtio_reset_device(vdev); + + ret = device_for_each_child(&vdev->dev, NULL, rpmsg_remove_device); + if (ret) + dev_warn(&vdev->dev, "can't remove rpmsg device: %d\n", ret); + + idr_destroy(&vrp->endpoints); + + vdev->config->del_vqs(vrp->vdev); + + dma_free_coherent(vdev->dev.parent, total_buf_space, + vrp->rbufs, vrp->bufs_dma); + + kfree(vrp); +} + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_RPMSG, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static unsigned int features[] = { + VIRTIO_RPMSG_F_NS, +}; + +static struct virtio_driver virtio_ipc_driver = { + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = rpmsg_probe, + .remove = rpmsg_remove, +}; + +static int __init rpmsg_init(void) +{ + int ret; + + ret = register_virtio_driver(&virtio_ipc_driver); + if (ret) + pr_err("failed to register virtio driver: %d\n", ret); + + return ret; +} +subsys_initcall(rpmsg_init); + +static void __exit rpmsg_fini(void) +{ + unregister_virtio_driver(&virtio_ipc_driver); +} +module_exit(rpmsg_fini); + +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio-based remote processor messaging bus"); +MODULE_LICENSE("GPL v2"); |