/*
* 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>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) "%s: " fmt, __func__
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_config.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/jiffies.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/rpmsg.h>
#include <linux/mutex.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
* @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
* @ns_ept: the bus's name service endpoint
*
* 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;
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;
struct rpmsg_endpoint *ns_ept;
};
/**
* struct rpmsg_channel_info - internal channel info representation
* @name: name of service
* @src: local address
* @dst: destination address
*/
struct rpmsg_channel_info {
char name[RPMSG_NAME_SIZE];
u32 src;
u32 dst;
};
#define to_rpmsg_channel(d) container_of(d, struct rpmsg_channel, dev)
#define to_rpmsg_driver(d) container_of(d, struct rpmsg_driver, drv)
/*
* 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 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)
/* Address 53 is reserved for advertising remote services */
#define RPMSG_NS_ADDR (53)
/* sysfs show configuration fields */
#define rpmsg_show_attr(field, path, format_string) \
static ssize_t \
field##_show(struct device *dev, \
struct device_attribute *attr, char *buf) \
{ \
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev); \
\
return sprintf(buf, format_string, rpdev->path); \
}
/* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
rpmsg_show_attr(name, id.name, "%s\n");
rpmsg_show_attr(src, src, "0x%x\n");
rpmsg_show_attr(dst, dst, "0x%x\n");
rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
/*
* Unique (and free running) index for rpmsg devices.
*
* Yeah, we're not recycling those numbers (yet?). will be easy
* to change if/when we want to.
*/
static unsigned int rpmsg_dev_index;
static ssize_t modalias_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
return sprintf(buf, RPMSG_DEVICE_MODALIAS_FMT "\n", rpdev->id.name);
}
static struct device_attribute rpmsg_dev_attrs[] = {
__ATTR_RO(name),
__ATTR_RO(modalias),
__ATTR_RO(dst),
__ATTR_RO(src),
__ATTR_RO(announce),
__ATTR_NULL
};
/* rpmsg devices and drivers are matched using the service name */
static inline int rpmsg_id_match(const struct rpmsg_channel *rpdev,
const struct rpmsg_device_id *id)
{
return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
}
/* match rpmsg channel and rpmsg driver */
static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
{
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv);
const struct rpmsg_device_id *ids = rpdrv->id_table;
unsigned int i;
for (i = 0; ids[i].name[0]; i++)
if (rpmsg_id_match(rpdev, &ids[i]))
return 1;
return 0;
}
static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
{
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
return add_uevent_var(env, "MODALIAS=" RPMSG_DEVICE_MODALIAS_FMT,
rpdev->id.name);
}
/**
* __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_channel *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) {
dev_err(dev, "failed to kzalloc a new ept\n");
return NULL;
}
kref_init(&ept->refcount);
mutex_init(&ept->cb_lock);
ept->rpdev = rpdev;
ept->cb = cb;
ept->priv = priv;
/* 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;
}
/**
* rpmsg_create_ept() - create a new rpmsg_endpoint
* @rpdev: rpmsg channel device
* @cb: rx callback handler
* @priv: private data for the driver's use
* @addr: local rpmsg address to bind with @cb
*
* Every rpmsg address in the system is bound to an rx callback (so when
* inbound messages arrive, they are dispatched by the rpmsg bus using the
* appropriate callback handler) by means of an rpmsg_endpoint struct.
*
* This function allows drivers to create such an endpoint, and by that,
* bind a callback, and possibly some private data too, to an rpmsg address
* (either one that is known in advance, or one that will be dynamically
* assigned for them).
*
* Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
* is already created for them when they are probed by the rpmsg bus
* (using the rx callback provided when they registered to the rpmsg bus).
*
* So things should just work for simple drivers: they already have an
* endpoint, their rx callback is bound to their rpmsg address, and when
* relevant inbound messages arrive (i.e. messages which their dst address
* equals to the src address of their rpmsg channel), the driver's handler
* is invoked to process it.
*
* That said, more complicated drivers might do need to allocate
* additional rpmsg addresses, and bind them to different rx callbacks.
* To accomplish that, those drivers need to call this function.
*
* Drivers should provide their @rpdev channel (so the new endpoint would belong
* to the same remote processor their channel belongs to), an rx callback
* function, an optional private data (which is provided back when the
* rx callback is invoked), and an address they want to bind with the
* callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
* dynamically assign them an available rpmsg address (drivers should have
* a very good reason why not to always use RPMSG_ADDR_ANY here).
*
* Returns a pointer to the endpoint on success, or NULL on error.
*/
struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_channel *rpdev,
rpmsg_rx_cb_t cb, void *priv, u32 addr)
{
return __rpmsg_create_ept(rpdev->vrp, rpdev, cb, priv, addr);
}
EXPORT_SYMBOL(rpmsg_create_ept);
/**
* __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);
}
/**
* rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
* @ept: endpoing to destroy
*
* Should be used by drivers to destroy an rpmsg endpoint previously
* created with rpmsg_create_ept().
*/
void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
{
__rpmsg_destroy_ept(ept->rpdev->vrp, ept);
}
EXPORT_SYMBOL(rpmsg_destroy_ept);
/*
* when an rpmsg driver is probed with a channel, we seamlessly create
* it an endpoint, binding its rx callback to a unique local rpmsg
* address.
*
* if we need to, we also announce about this channel to the remote
* processor (needed in case the driver is exposing an rpmsg service).
*/
static int rpmsg_dev_probe(struct device *dev)
{
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
struct virtproc_info *vrp = rpdev->vrp;
struct rpmsg_endpoint *ept;
int err;
ept = rpmsg_create_ept(rpdev, rpdrv->callback, NULL, rpdev->src);
if (!ept) {
dev_err(dev, "failed to create endpoint\n");
err = -ENOMEM;
goto out;
}
rpdev->ept = ept;
rpdev->src = ept->addr;
err = rpdrv->probe(rpdev);
if (err) {
dev_err(dev, "%s: failed: %d\n", __func__, err);
rpmsg_destroy_ept(ept);
goto out;
}
/* need to tell remote processor's name service about this channel ? */
if (rpdev->announce &&
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 = rpdev->src;
nsm.flags = RPMSG_NS_CREATE;
err = rpmsg_sendto(rpdev, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
if (err)
dev_err(dev, "failed to announce service %d\n", err);
}
out:
return err;
}
static int rpmsg_dev_remove(struct device *dev)
{
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
struct virtproc_info *vrp = rpdev->vrp;
int err = 0;
/* tell remote processor's name service we're removing this channel */
if (rpdev->announce &&
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 = rpdev->src;
nsm.flags = RPMSG_NS_DESTROY;
err = rpmsg_sendto(rpdev, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
if (err)
dev_err(dev, "failed to announce service %d\n", err);
}
rpdrv->remove(rpdev);
rpmsg_destroy_ept(rpdev->ept);
return err;
}
static struct bus_type rpmsg_bus = {
.name = "rpmsg",
.match = rpmsg_dev_match,
.dev_attrs = rpmsg_dev_attrs,
.uevent = rpmsg_uevent,
.probe = rpmsg_dev_probe,
.remove = rpmsg_dev_remove,
};
/**
* register_rpmsg_driver() - register an rpmsg driver with the rpmsg bus
* @rpdrv: pointer to a struct rpmsg_driver
*
* Returns 0 on success, and an appropriate error value on failure.
*/
int register_rpmsg_driver(struct rpmsg_driver *rpdrv)
{
rpdrv->drv.bus = &rpmsg_bus;
return driver_register(&rpdrv->drv);
}
EXPORT_SYMBOL(register_rpmsg_driver);
/**
* unregister_rpmsg_driver() - unregister an rpmsg driver from the rpmsg bus
* @rpdrv: pointer to a struct rpmsg_driver
*
* Returns 0 on success, and an appropriate error value on failure.
*/
void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv)
{
driver_unregister(&rpdrv->drv);
}
EXPORT_SYMBOL(unregister_rpmsg_driver);
static void rpmsg_release_device(struct device *dev)
{
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
kfree(rpdev);
}
/*
* match an rpmsg channel with a channel info struct.
* this is used to make sure we're not creating rpmsg devices for channels
* that already exist.
*/
static int rpmsg_channel_match(struct device *dev, void *data)
{
struct rpmsg_channel_info *chinfo = data;
struct rpmsg_channel *rpdev = to_rpmsg_channel(dev);
if (chinfo->src != RPMSG_ADDR_ANY && chinfo->src != rpdev->src)
return 0;
if (chinfo->dst != RPMSG_ADDR_ANY && chinfo->dst != rpdev->dst)
return 0;
if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))
return 0;
/* found a match ! */
return 1;
}
/*
* 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_channel *rpmsg_create_channel(struct virtproc_info *vrp,
struct rpmsg_channel_info *chinfo)
{
struct rpmsg_channel *rpdev;
struct device *tmp, *dev = &vrp->vdev->dev;
int ret;
/* make sure a similar channel doesn't already exist */
tmp = device_find_child(dev, chinfo, rpmsg_channel_match);
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;
}
rpdev = kzalloc(sizeof(struct rpmsg_channel), GFP_KERNEL);
if (!rpdev) {
pr_err("kzalloc failed\n");
return NULL;
}
rpdev->vrp = vrp;
rpdev->src = chinfo->src;
rpdev->dst = chinfo->dst;
/*
* rpmsg server channels has predefined local address (for now),
* and their existence needs to be announced remotely
*/
rpdev->announce = rpdev->src != RPMSG_ADDR_ANY ? true : false;
strncpy(rpdev->id.name, chinfo->name, RPMSG_NAME_SIZE);
/* very simple device indexing plumbing which is enough for now */
dev_set_name(&rpdev->dev, "rpmsg%d", rpmsg_dev_index++);
rpdev->dev.parent = &vrp->vdev->dev;
rpdev->dev.bus = &rpmsg_bus;
rpdev->dev.release = rpmsg_release_device;
ret = device_register(&rpdev->dev);
if (ret) {
dev_err(dev, "device_register failed: %d\n", ret);
put_device(&rpdev->dev);
return NULL;
}
return rpdev;
}
/*
* find an existing channel using its name + address properties,
* and destroy it
*/
static int rpmsg_destroy_channel(struct virtproc_info *vrp,
struct rpmsg_channel_info *chinfo)
{
struct virtio_device *vdev = vrp->vdev;
struct device *dev;
dev = device_find_child(&vdev->dev, chinfo, rpmsg_channel_match);
if (!dev)
return -EINVAL;
device_unregister(dev);
put_device(dev);
return 0;
}
/* 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 + RPMSG_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).
*
* Returns 0 on success and an appropriate error value on failure.
*/
int rpmsg_send_offchannel_raw(struct rpmsg_channel *rpdev, u32 src, u32 dst,
void *data, int len, bool wait)
{
struct virtproc_info *vrp = rpdev->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 > RPMSG_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 = len;
msg->flags = 0;
msg->src = src;
msg->dst = 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",
msg->src, msg->dst, msg->len,
msg->flags, msg->reserved);
print_hex_dump(KERN_DEBUG, "rpmsg_virtio TX: ", DUMP_PREFIX_NONE, 16, 1,
msg, sizeof(*msg) + msg->len, true);
sg_init_one(&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;
}
EXPORT_SYMBOL(rpmsg_send_offchannel_raw);
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;
int err;
dev_dbg(dev, "From: 0x%x, To: 0x%x, Len: %d, Flags: %d, Reserved: %d\n",
msg->src, msg->dst, msg->len,
msg->flags, msg->reserved);
print_hex_dump(KERN_DEBUG, "rpmsg_virtio RX: ", DUMP_PREFIX_NONE, 16, 1,
msg, sizeof(*msg) + msg->len, true);
/*
* We currently use fixed-sized buffers, so trivially sanitize
* the reported payload length.
*/
if (len > RPMSG_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, 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,
msg->src);
mutex_unlock(&ept->cb_lock);
/* farewell, ept, we don't need you anymore */
kref_put(&ept->refcount, __ept_release);
} else
dev_warn(dev, "msg received with no recipient\n");
/* publish the real size of the buffer */
sg_init_one(&sg, msg, RPMSG_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);
}
/* invoked when a name service announcement arrives */
static void rpmsg_ns_cb(struct rpmsg_channel *rpdev, void *data, int len,
void *priv, u32 src)
{
struct rpmsg_ns_msg *msg = data;
struct rpmsg_channel *newch;
struct rpmsg_channel_info chinfo;
struct virtproc_info *vrp = priv;
struct device *dev = &vrp->vdev->dev;
int ret;
print_hex_dump(KERN_DEBUG, "NS announcement: ",
DUMP_PREFIX_NONE, 16, 1,
data, len, true);
if (len != sizeof(*msg)) {
dev_err(dev, "malformed ns msg (%d)\n", len);
return;
}
/*
* the name service ept does _not_ belong to a real rpmsg channel,
* and is handled by the rpmsg bus itself.
* for sanity reasons, make sure a valid rpdev has _not_ sneaked
* in somehow.
*/
if (rpdev) {
dev_err(dev, "anomaly: ns ept has an rpdev handle\n");
return;
}
/* don't trust the remote processor for null terminating the name */
msg->name[RPMSG_NAME_SIZE - 1] = '\0';
dev_info(dev, "%sing channel %s addr 0x%x\n",
msg->flags & RPMSG_NS_DESTROY ? "destroy" : "creat",
msg->name, msg->addr);
strncpy(chinfo.name, msg->name, sizeof(chinfo.name));
chinfo.src = RPMSG_ADDR_ANY;
chinfo.dst = msg->addr;
if (msg->flags & RPMSG_NS_DESTROY) {
ret = rpmsg_destroy_channel(vrp, &chinfo);
if (ret)
dev_err(dev, "rpmsg_destroy_channel failed: %d\n", ret);
} else {
newch = rpmsg_create_channel(vrp, &chinfo);
if (!newch)
dev_err(dev, "rpmsg_create_channel failed\n");
}
}
static int rpmsg_probe(struct virtio_device *vdev)
{
vq_callback_t *vq_cbs[] = { rpmsg_recv_done, rpmsg_xmit_done };
const char *names[] = { "input", "output" };
struct virtqueue *vqs[2];
struct virtproc_info *vrp;
void *bufs_va;
int err = 0, i;
size_t total_buf_space;
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 = vdev->config->find_vqs(vdev, 2, vqs, vq_cbs, names);
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;
total_buf_space = vrp->num_bufs * RPMSG_BUF_SIZE;
/* allocate coherent memory for the buffers */
bufs_va = dma_alloc_coherent(vdev->dev.parent->parent,
total_buf_space, &vrp->bufs_dma,
GFP_KERNEL);
if (!bufs_va) {
err = -ENOMEM;
goto vqs_del;
}
dev_dbg(&vdev->dev, "buffers: va %p, dma 0x%llx\n", bufs_va,
(unsigned long long)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 * RPMSG_BUF_SIZE;
sg_init_one(&sg, cpu_addr, RPMSG_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;
/* if supported by the remote processor, enable the name service */
if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_NS)) {
/* a dedicated endpoint handles the name service msgs */
vrp->ns_ept = __rpmsg_create_ept(vrp, NULL, rpmsg_ns_cb,
vrp, RPMSG_NS_ADDR);
if (!vrp->ns_ept) {
dev_err(&vdev->dev, "failed to create the ns ept\n");
err = -ENOMEM;
goto free_coherent;
}
}
/* tell the remote processor it can start sending messages */
virtqueue_kick(vrp->rvq);
dev_info(&vdev->dev, "rpmsg host is online\n");
return 0;
free_coherent:
dma_free_coherent(vdev->dev.parent->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 * RPMSG_BUF_SIZE;
int ret;
vdev->config->reset(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);
if (vrp->ns_ept)
__rpmsg_destroy_ept(vrp, vrp->ns_ept);
idr_destroy(&vrp->endpoints);
vdev->config->del_vqs(vrp->vdev);
dma_free_coherent(vdev->dev.parent->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 = bus_register(&rpmsg_bus);
if (ret) {
pr_err("failed to register rpmsg bus: %d\n", ret);
return ret;
}
ret = register_virtio_driver(&virtio_ipc_driver);
if (ret) {
pr_err("failed to register virtio driver: %d\n", ret);
bus_unregister(&rpmsg_bus);
}
return ret;
}
subsys_initcall(rpmsg_init);
static void __exit rpmsg_fini(void)
{
unregister_virtio_driver(&virtio_ipc_driver);
bus_unregister(&rpmsg_bus);
}
module_exit(rpmsg_fini);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio-based remote processor messaging bus");
MODULE_LICENSE("GPL v2");
