| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Igor Skalkin | 1832 | 56.77% | 1 | 5.00% |
| Cristian Marussi | 1306 | 40.47% | 13 | 65.00% |
| Sudeep Holla | 67 | 2.08% | 3 | 15.00% |
| Viresh Kumar | 19 | 0.59% | 1 | 5.00% |
| Lukasz Luba | 2 | 0.06% | 1 | 5.00% |
| Michael S. Tsirkin | 1 | 0.03% | 1 | 5.00% |
| Total | 3227 | 20 |
// SPDX-License-Identifier: GPL-2.0 /* * Virtio Transport driver for Arm System Control and Management Interface * (SCMI). * * Copyright (C) 2020-2022 OpenSynergy. * Copyright (C) 2021-2022 ARM Ltd. */ /** * DOC: Theory of Operation * * The scmi-virtio transport implements a driver for the virtio SCMI device. * * There is one Tx channel (virtio cmdq, A2P channel) and at most one Rx * channel (virtio eventq, P2A channel). Each channel is implemented through a * virtqueue. Access to each virtqueue is protected by spinlocks. */ #include <linux/completion.h> #include <linux/errno.h> #include <linux/refcount.h> #include <linux/slab.h> #include <linux/virtio.h> #include <linux/virtio_config.h> #include <uapi/linux/virtio_ids.h> #include <uapi/linux/virtio_scmi.h> #include "common.h" #define VIRTIO_MAX_RX_TIMEOUT_MS 60000 #define VIRTIO_SCMI_MAX_MSG_SIZE 128 /* Value may be increased. */ #define VIRTIO_SCMI_MAX_PDU_SIZE \ (VIRTIO_SCMI_MAX_MSG_SIZE + SCMI_MSG_MAX_PROT_OVERHEAD) #define DESCRIPTORS_PER_TX_MSG 2 /** * struct scmi_vio_channel - Transport channel information * * @vqueue: Associated virtqueue * @cinfo: SCMI Tx or Rx channel * @free_lock: Protects access to the @free_list. * @free_list: List of unused scmi_vio_msg, maintained for Tx channels only * @deferred_tx_work: Worker for TX deferred replies processing * @deferred_tx_wq: Workqueue for TX deferred replies * @pending_lock: Protects access to the @pending_cmds_list. * @pending_cmds_list: List of pre-fetched commands queueud for later processing * @is_rx: Whether channel is an Rx channel * @max_msg: Maximum number of pending messages for this channel. * @lock: Protects access to all members except users, free_list and * pending_cmds_list. * @shutdown_done: A reference to a completion used when freeing this channel. * @users: A reference count to currently active users of this channel. */ struct scmi_vio_channel { struct virtqueue *vqueue; struct scmi_chan_info *cinfo; /* lock to protect access to the free list. */ spinlock_t free_lock; struct list_head free_list; /* lock to protect access to the pending list. */ spinlock_t pending_lock; struct list_head pending_cmds_list; struct work_struct deferred_tx_work; struct workqueue_struct *deferred_tx_wq; bool is_rx; unsigned int max_msg; /* * Lock to protect access to all members except users, free_list and * pending_cmds_list */ spinlock_t lock; struct completion *shutdown_done; refcount_t users; }; enum poll_states { VIO_MSG_NOT_POLLED, VIO_MSG_POLL_TIMEOUT, VIO_MSG_POLLING, VIO_MSG_POLL_DONE, }; /** * struct scmi_vio_msg - Transport PDU information * * @request: SDU used for commands * @input: SDU used for (delayed) responses and notifications * @list: List which scmi_vio_msg may be part of * @rx_len: Input SDU size in bytes, once input has been received * @poll_idx: Last used index registered for polling purposes if this message * transaction reply was configured for polling. * @poll_status: Polling state for this message. * @poll_lock: A lock to protect @poll_status * @users: A reference count to track this message users and avoid premature * freeing (and reuse) when polling and IRQ execution paths interleave. */ struct scmi_vio_msg { struct scmi_msg_payld *request; struct scmi_msg_payld *input; struct list_head list; unsigned int rx_len; unsigned int poll_idx; enum poll_states poll_status; /* Lock to protect access to poll_status */ spinlock_t poll_lock; refcount_t users; }; /* Only one SCMI VirtIO device can possibly exist */ static struct virtio_device *scmi_vdev; static void scmi_vio_channel_ready(struct scmi_vio_channel *vioch, struct scmi_chan_info *cinfo) { unsigned long flags; spin_lock_irqsave(&vioch->lock, flags); cinfo->transport_info = vioch; /* Indirectly setting channel not available any more */ vioch->cinfo = cinfo; spin_unlock_irqrestore(&vioch->lock, flags); refcount_set(&vioch->users, 1); } static inline bool scmi_vio_channel_acquire(struct scmi_vio_channel *vioch) { return refcount_inc_not_zero(&vioch->users); } static inline void scmi_vio_channel_release(struct scmi_vio_channel *vioch) { if (refcount_dec_and_test(&vioch->users)) { unsigned long flags; spin_lock_irqsave(&vioch->lock, flags); if (vioch->shutdown_done) { vioch->cinfo = NULL; complete(vioch->shutdown_done); } spin_unlock_irqrestore(&vioch->lock, flags); } } static void scmi_vio_channel_cleanup_sync(struct scmi_vio_channel *vioch) { unsigned long flags; DECLARE_COMPLETION_ONSTACK(vioch_shutdown_done); /* * Prepare to wait for the last release if not already released * or in progress. */ spin_lock_irqsave(&vioch->lock, flags); if (!vioch->cinfo || vioch->shutdown_done) { spin_unlock_irqrestore(&vioch->lock, flags); return; } vioch->shutdown_done = &vioch_shutdown_done; if (!vioch->is_rx && vioch->deferred_tx_wq) /* Cannot be kicked anymore after this...*/ vioch->deferred_tx_wq = NULL; spin_unlock_irqrestore(&vioch->lock, flags); scmi_vio_channel_release(vioch); /* Let any possibly concurrent RX path release the channel */ wait_for_completion(vioch->shutdown_done); } /* Assumes to be called with vio channel acquired already */ static struct scmi_vio_msg * scmi_virtio_get_free_msg(struct scmi_vio_channel *vioch) { unsigned long flags; struct scmi_vio_msg *msg; spin_lock_irqsave(&vioch->free_lock, flags); if (list_empty(&vioch->free_list)) { spin_unlock_irqrestore(&vioch->free_lock, flags); return NULL; } msg = list_first_entry(&vioch->free_list, typeof(*msg), list); list_del_init(&msg->list); spin_unlock_irqrestore(&vioch->free_lock, flags); /* Still no users, no need to acquire poll_lock */ msg->poll_status = VIO_MSG_NOT_POLLED; refcount_set(&msg->users, 1); return msg; } static inline bool scmi_vio_msg_acquire(struct scmi_vio_msg *msg) { return refcount_inc_not_zero(&msg->users); } /* Assumes to be called with vio channel acquired already */ static inline bool scmi_vio_msg_release(struct scmi_vio_channel *vioch, struct scmi_vio_msg *msg) { bool ret; ret = refcount_dec_and_test(&msg->users); if (ret) { unsigned long flags; spin_lock_irqsave(&vioch->free_lock, flags); list_add_tail(&msg->list, &vioch->free_list); spin_unlock_irqrestore(&vioch->free_lock, flags); } return ret; } static bool scmi_vio_have_vq_rx(struct virtio_device *vdev) { return virtio_has_feature(vdev, VIRTIO_SCMI_F_P2A_CHANNELS); } static int scmi_vio_feed_vq_rx(struct scmi_vio_channel *vioch, struct scmi_vio_msg *msg) { struct scatterlist sg_in; int rc; unsigned long flags; struct device *dev = &vioch->vqueue->vdev->dev; sg_init_one(&sg_in, msg->input, VIRTIO_SCMI_MAX_PDU_SIZE); spin_lock_irqsave(&vioch->lock, flags); rc = virtqueue_add_inbuf(vioch->vqueue, &sg_in, 1, msg, GFP_ATOMIC); if (rc) dev_err(dev, "failed to add to RX virtqueue (%d)\n", rc); else virtqueue_kick(vioch->vqueue); spin_unlock_irqrestore(&vioch->lock, flags); return rc; } /* * Assume to be called with channel already acquired or not ready at all; * vioch->lock MUST NOT have been already acquired. */ static void scmi_finalize_message(struct scmi_vio_channel *vioch, struct scmi_vio_msg *msg) { if (vioch->is_rx) scmi_vio_feed_vq_rx(vioch, msg); else scmi_vio_msg_release(vioch, msg); } static void scmi_vio_complete_cb(struct virtqueue *vqueue) { unsigned long flags; unsigned int length; struct scmi_vio_channel *vioch; struct scmi_vio_msg *msg; bool cb_enabled = true; if (WARN_ON_ONCE(!vqueue->vdev->priv)) return; vioch = &((struct scmi_vio_channel *)vqueue->vdev->priv)[vqueue->index]; for (;;) { if (!scmi_vio_channel_acquire(vioch)) return; spin_lock_irqsave(&vioch->lock, flags); if (cb_enabled) { virtqueue_disable_cb(vqueue); cb_enabled = false; } msg = virtqueue_get_buf(vqueue, &length); if (!msg) { if (virtqueue_enable_cb(vqueue)) { spin_unlock_irqrestore(&vioch->lock, flags); scmi_vio_channel_release(vioch); return; } cb_enabled = true; } spin_unlock_irqrestore(&vioch->lock, flags); if (msg) { msg->rx_len = length; scmi_rx_callback(vioch->cinfo, msg_read_header(msg->input), msg); scmi_finalize_message(vioch, msg); } /* * Release vio channel between loop iterations to allow * virtio_chan_free() to eventually fully release it when * shutting down; in such a case, any outstanding message will * be ignored since this loop will bail out at the next * iteration. */ scmi_vio_channel_release(vioch); } } static void scmi_vio_deferred_tx_worker(struct work_struct *work) { unsigned long flags; struct scmi_vio_channel *vioch; struct scmi_vio_msg *msg, *tmp; vioch = container_of(work, struct scmi_vio_channel, deferred_tx_work); if (!scmi_vio_channel_acquire(vioch)) return; /* * Process pre-fetched messages: these could be non-polled messages or * late timed-out replies to polled messages dequeued by chance while * polling for some other messages: this worker is in charge to process * the valid non-expired messages and anyway finally free all of them. */ spin_lock_irqsave(&vioch->pending_lock, flags); /* Scan the list of possibly pre-fetched messages during polling. */ list_for_each_entry_safe(msg, tmp, &vioch->pending_cmds_list, list) { list_del(&msg->list); /* * Channel is acquired here (cannot vanish) and this message * is no more processed elsewhere so no poll_lock needed. */ if (msg->poll_status == VIO_MSG_NOT_POLLED) scmi_rx_callback(vioch->cinfo, msg_read_header(msg->input), msg); /* Free the processed message once done */ scmi_vio_msg_release(vioch, msg); } spin_unlock_irqrestore(&vioch->pending_lock, flags); /* Process possibly still pending messages */ scmi_vio_complete_cb(vioch->vqueue); scmi_vio_channel_release(vioch); } static const char *const scmi_vio_vqueue_names[] = { "tx", "rx" }; static vq_callback_t *scmi_vio_complete_callbacks[] = { scmi_vio_complete_cb, scmi_vio_complete_cb }; static unsigned int virtio_get_max_msg(struct scmi_chan_info *base_cinfo) { struct scmi_vio_channel *vioch = base_cinfo->transport_info; return vioch->max_msg; } static int virtio_link_supplier(struct device *dev) { if (!scmi_vdev) { dev_notice(dev, "Deferring probe after not finding a bound scmi-virtio device\n"); return -EPROBE_DEFER; } if (!device_link_add(dev, &scmi_vdev->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) { dev_err(dev, "Adding link to supplier virtio device failed\n"); return -ECANCELED; } return 0; } static bool virtio_chan_available(struct device_node *of_node, int idx) { struct scmi_vio_channel *channels, *vioch = NULL; if (WARN_ON_ONCE(!scmi_vdev)) return false; channels = (struct scmi_vio_channel *)scmi_vdev->priv; switch (idx) { case VIRTIO_SCMI_VQ_TX: vioch = &channels[VIRTIO_SCMI_VQ_TX]; break; case VIRTIO_SCMI_VQ_RX: if (scmi_vio_have_vq_rx(scmi_vdev)) vioch = &channels[VIRTIO_SCMI_VQ_RX]; break; default: return false; } return vioch && !vioch->cinfo; } static void scmi_destroy_tx_workqueue(void *deferred_tx_wq) { destroy_workqueue(deferred_tx_wq); } static int virtio_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, bool tx) { struct scmi_vio_channel *vioch; int index = tx ? VIRTIO_SCMI_VQ_TX : VIRTIO_SCMI_VQ_RX; int i; if (!scmi_vdev) return -EPROBE_DEFER; vioch = &((struct scmi_vio_channel *)scmi_vdev->priv)[index]; /* Setup a deferred worker for polling. */ if (tx && !vioch->deferred_tx_wq) { int ret; vioch->deferred_tx_wq = alloc_workqueue(dev_name(&scmi_vdev->dev), WQ_UNBOUND | WQ_FREEZABLE | WQ_SYSFS, 0); if (!vioch->deferred_tx_wq) return -ENOMEM; ret = devm_add_action_or_reset(dev, scmi_destroy_tx_workqueue, vioch->deferred_tx_wq); if (ret) return ret; INIT_WORK(&vioch->deferred_tx_work, scmi_vio_deferred_tx_worker); } for (i = 0; i < vioch->max_msg; i++) { struct scmi_vio_msg *msg; msg = devm_kzalloc(dev, sizeof(*msg), GFP_KERNEL); if (!msg) return -ENOMEM; if (tx) { msg->request = devm_kzalloc(dev, VIRTIO_SCMI_MAX_PDU_SIZE, GFP_KERNEL); if (!msg->request) return -ENOMEM; spin_lock_init(&msg->poll_lock); refcount_set(&msg->users, 1); } msg->input = devm_kzalloc(dev, VIRTIO_SCMI_MAX_PDU_SIZE, GFP_KERNEL); if (!msg->input) return -ENOMEM; scmi_finalize_message(vioch, msg); } scmi_vio_channel_ready(vioch, cinfo); return 0; } static int virtio_chan_free(int id, void *p, void *data) { struct scmi_chan_info *cinfo = p; struct scmi_vio_channel *vioch = cinfo->transport_info; /* * Break device to inhibit further traffic flowing while shutting down * the channels: doing it later holding vioch->lock creates unsafe * locking dependency chains as reported by LOCKDEP. */ virtio_break_device(vioch->vqueue->vdev); scmi_vio_channel_cleanup_sync(vioch); return 0; } static int virtio_send_message(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) { struct scmi_vio_channel *vioch = cinfo->transport_info; struct scatterlist sg_out; struct scatterlist sg_in; struct scatterlist *sgs[DESCRIPTORS_PER_TX_MSG] = { &sg_out, &sg_in }; unsigned long flags; int rc; struct scmi_vio_msg *msg; if (!scmi_vio_channel_acquire(vioch)) return -EINVAL; msg = scmi_virtio_get_free_msg(vioch); if (!msg) { scmi_vio_channel_release(vioch); return -EBUSY; } msg_tx_prepare(msg->request, xfer); sg_init_one(&sg_out, msg->request, msg_command_size(xfer)); sg_init_one(&sg_in, msg->input, msg_response_size(xfer)); spin_lock_irqsave(&vioch->lock, flags); /* * If polling was requested for this transaction: * - retrieve last used index (will be used as polling reference) * - bind the polled message to the xfer via .priv * - grab an additional msg refcount for the poll-path */ if (xfer->hdr.poll_completion) { msg->poll_idx = virtqueue_enable_cb_prepare(vioch->vqueue); /* Still no users, no need to acquire poll_lock */ msg->poll_status = VIO_MSG_POLLING; scmi_vio_msg_acquire(msg); /* Ensure initialized msg is visibly bound to xfer */ smp_store_mb(xfer->priv, msg); } rc = virtqueue_add_sgs(vioch->vqueue, sgs, 1, 1, msg, GFP_ATOMIC); if (rc) dev_err(vioch->cinfo->dev, "failed to add to TX virtqueue (%d)\n", rc); else virtqueue_kick(vioch->vqueue); spin_unlock_irqrestore(&vioch->lock, flags); if (rc) { /* Ensure order between xfer->priv clear and vq feeding */ smp_store_mb(xfer->priv, NULL); if (xfer->hdr.poll_completion) scmi_vio_msg_release(vioch, msg); scmi_vio_msg_release(vioch, msg); } scmi_vio_channel_release(vioch); return rc; } static void virtio_fetch_response(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) { struct scmi_vio_msg *msg = xfer->priv; if (msg) msg_fetch_response(msg->input, msg->rx_len, xfer); } static void virtio_fetch_notification(struct scmi_chan_info *cinfo, size_t max_len, struct scmi_xfer *xfer) { struct scmi_vio_msg *msg = xfer->priv; if (msg) msg_fetch_notification(msg->input, msg->rx_len, max_len, xfer); } /** * virtio_mark_txdone - Mark transmission done * * Free only completed polling transfer messages. * * Note that in the SCMI VirtIO transport we never explicitly release still * outstanding but timed-out messages by forcibly re-adding them to the * free-list inside the TX code path; we instead let IRQ/RX callbacks, or the * TX deferred worker, eventually clean up such messages once, finally, a late * reply is received and discarded (if ever). * * This approach was deemed preferable since those pending timed-out buffers are * still effectively owned by the SCMI platform VirtIO device even after timeout * expiration: forcibly freeing and reusing them before they had been returned * explicitly by the SCMI platform could lead to subtle bugs due to message * corruption. * An SCMI platform VirtIO device which never returns message buffers is * anyway broken and it will quickly lead to exhaustion of available messages. * * For this same reason, here, we take care to free only the polled messages * that had been somehow replied (only if not by chance already processed on the * IRQ path - the initial scmi_vio_msg_release() takes care of this) and also * any timed-out polled message if that indeed appears to have been at least * dequeued from the virtqueues (VIO_MSG_POLL_DONE): this is needed since such * messages won't be freed elsewhere. Any other polled message is marked as * VIO_MSG_POLL_TIMEOUT. * * Possible late replies to timed-out polled messages will be eventually freed * by RX callbacks if delivered on the IRQ path or by the deferred TX worker if * dequeued on some other polling path. * * @cinfo: SCMI channel info * @ret: Transmission return code * @xfer: Transfer descriptor */ static void virtio_mark_txdone(struct scmi_chan_info *cinfo, int ret, struct scmi_xfer *xfer) { unsigned long flags; struct scmi_vio_channel *vioch = cinfo->transport_info; struct scmi_vio_msg *msg = xfer->priv; if (!msg || !scmi_vio_channel_acquire(vioch)) return; /* Ensure msg is unbound from xfer anyway at this point */ smp_store_mb(xfer->priv, NULL); /* Must be a polled xfer and not already freed on the IRQ path */ if (!xfer->hdr.poll_completion || scmi_vio_msg_release(vioch, msg)) { scmi_vio_channel_release(vioch); return; } spin_lock_irqsave(&msg->poll_lock, flags); /* Do not free timedout polled messages only if still inflight */ if (ret != -ETIMEDOUT || msg->poll_status == VIO_MSG_POLL_DONE) scmi_vio_msg_release(vioch, msg); else if (msg->poll_status == VIO_MSG_POLLING) msg->poll_status = VIO_MSG_POLL_TIMEOUT; spin_unlock_irqrestore(&msg->poll_lock, flags); scmi_vio_channel_release(vioch); } /** * virtio_poll_done - Provide polling support for VirtIO transport * * @cinfo: SCMI channel info * @xfer: Reference to the transfer being poll for. * * VirtIO core provides a polling mechanism based only on last used indexes: * this means that it is possible to poll the virtqueues waiting for something * new to arrive from the host side, but the only way to check if the freshly * arrived buffer was indeed what we were waiting for is to compare the newly * arrived message descriptor with the one we are polling on. * * As a consequence it can happen to dequeue something different from the buffer * we were poll-waiting for: if that is the case such early fetched buffers are * then added to a the @pending_cmds_list list for later processing by a * dedicated deferred worker. * * So, basically, once something new is spotted we proceed to de-queue all the * freshly received used buffers until we found the one we were polling on, or, * we have 'seemingly' emptied the virtqueue; if some buffers are still pending * in the vqueue at the end of the polling loop (possible due to inherent races * in virtqueues handling mechanisms), we similarly kick the deferred worker * and let it process those, to avoid indefinitely looping in the .poll_done * busy-waiting helper. * * Finally, we delegate to the deferred worker also the final free of any timed * out reply to a polled message that we should dequeue. * * Note that, since we do NOT have per-message suppress notification mechanism, * the message we are polling for could be alternatively delivered via usual * IRQs callbacks on another core which happened to have IRQs enabled while we * are actively polling for it here: in such a case it will be handled as such * by scmi_rx_callback() and the polling loop in the SCMI Core TX path will be * transparently terminated anyway. * * Return: True once polling has successfully completed. */ static bool virtio_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) { bool pending, found = false; unsigned int length, any_prefetched = 0; unsigned long flags; struct scmi_vio_msg *next_msg, *msg = xfer->priv; struct scmi_vio_channel *vioch = cinfo->transport_info; if (!msg) return true; /* * Processed already by other polling loop on another CPU ? * * Note that this message is acquired on the poll path so cannot vanish * while inside this loop iteration even if concurrently processed on * the IRQ path. * * Avoid to acquire poll_lock since polled_status can be changed * in a relevant manner only later in this same thread of execution: * any other possible changes made concurrently by other polling loops * or by a reply delivered on the IRQ path have no meaningful impact on * this loop iteration: in other words it is harmless to allow this * possible race but let has avoid spinlocking with irqs off in this * initial part of the polling loop. */ if (msg->poll_status == VIO_MSG_POLL_DONE) return true; if (!scmi_vio_channel_acquire(vioch)) return true; /* Has cmdq index moved at all ? */ pending = virtqueue_poll(vioch->vqueue, msg->poll_idx); if (!pending) { scmi_vio_channel_release(vioch); return false; } spin_lock_irqsave(&vioch->lock, flags); virtqueue_disable_cb(vioch->vqueue); /* * Process all new messages till the polled-for message is found OR * the vqueue is empty. */ while ((next_msg = virtqueue_get_buf(vioch->vqueue, &length))) { bool next_msg_done = false; /* * Mark any dequeued buffer message as VIO_MSG_POLL_DONE so * that can be properly freed even on timeout in mark_txdone. */ spin_lock(&next_msg->poll_lock); if (next_msg->poll_status == VIO_MSG_POLLING) { next_msg->poll_status = VIO_MSG_POLL_DONE; next_msg_done = true; } spin_unlock(&next_msg->poll_lock); next_msg->rx_len = length; /* Is the message we were polling for ? */ if (next_msg == msg) { found = true; break; } else if (next_msg_done) { /* Skip the rest if this was another polled msg */ continue; } /* * Enqueue for later processing any non-polled message and any * timed-out polled one that we happen to have dequeued. */ spin_lock(&next_msg->poll_lock); if (next_msg->poll_status == VIO_MSG_NOT_POLLED || next_msg->poll_status == VIO_MSG_POLL_TIMEOUT) { spin_unlock(&next_msg->poll_lock); any_prefetched++; spin_lock(&vioch->pending_lock); list_add_tail(&next_msg->list, &vioch->pending_cmds_list); spin_unlock(&vioch->pending_lock); } else { spin_unlock(&next_msg->poll_lock); } } /* * When the polling loop has successfully terminated if something * else was queued in the meantime, it will be served by a deferred * worker OR by the normal IRQ/callback OR by other poll loops. * * If we are still looking for the polled reply, the polling index has * to be updated to the current vqueue last used index. */ if (found) { pending = !virtqueue_enable_cb(vioch->vqueue); } else { msg->poll_idx = virtqueue_enable_cb_prepare(vioch->vqueue); pending = virtqueue_poll(vioch->vqueue, msg->poll_idx); } if (vioch->deferred_tx_wq && (any_prefetched || pending)) queue_work(vioch->deferred_tx_wq, &vioch->deferred_tx_work); spin_unlock_irqrestore(&vioch->lock, flags); scmi_vio_channel_release(vioch); return found; } static const struct scmi_transport_ops scmi_virtio_ops = { .link_supplier = virtio_link_supplier, .chan_available = virtio_chan_available, .chan_setup = virtio_chan_setup, .chan_free = virtio_chan_free, .get_max_msg = virtio_get_max_msg, .send_message = virtio_send_message, .fetch_response = virtio_fetch_response, .fetch_notification = virtio_fetch_notification, .mark_txdone = virtio_mark_txdone, .poll_done = virtio_poll_done, }; static int scmi_vio_probe(struct virtio_device *vdev) { struct device *dev = &vdev->dev; struct scmi_vio_channel *channels; bool have_vq_rx; int vq_cnt; int i; int ret; struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT]; /* Only one SCMI VirtiO device allowed */ if (scmi_vdev) { dev_err(dev, "One SCMI Virtio device was already initialized: only one allowed.\n"); return -EBUSY; } have_vq_rx = scmi_vio_have_vq_rx(vdev); vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1; channels = devm_kcalloc(dev, vq_cnt, sizeof(*channels), GFP_KERNEL); if (!channels) return -ENOMEM; if (have_vq_rx) channels[VIRTIO_SCMI_VQ_RX].is_rx = true; ret = virtio_find_vqs(vdev, vq_cnt, vqs, scmi_vio_complete_callbacks, scmi_vio_vqueue_names, NULL); if (ret) { dev_err(dev, "Failed to get %d virtqueue(s)\n", vq_cnt); return ret; } for (i = 0; i < vq_cnt; i++) { unsigned int sz; spin_lock_init(&channels[i].lock); spin_lock_init(&channels[i].free_lock); INIT_LIST_HEAD(&channels[i].free_list); spin_lock_init(&channels[i].pending_lock); INIT_LIST_HEAD(&channels[i].pending_cmds_list); channels[i].vqueue = vqs[i]; sz = virtqueue_get_vring_size(channels[i].vqueue); /* Tx messages need multiple descriptors. */ if (!channels[i].is_rx) sz /= DESCRIPTORS_PER_TX_MSG; if (sz > MSG_TOKEN_MAX) { dev_info(dev, "%s virtqueue could hold %d messages. Only %ld allowed to be pending.\n", channels[i].is_rx ? "rx" : "tx", sz, MSG_TOKEN_MAX); sz = MSG_TOKEN_MAX; } channels[i].max_msg = sz; } vdev->priv = channels; /* Ensure initialized scmi_vdev is visible */ smp_store_mb(scmi_vdev, vdev); return 0; } static void scmi_vio_remove(struct virtio_device *vdev) { /* * Once we get here, virtio_chan_free() will have already been called by * the SCMI core for any existing channel and, as a consequence, all the * virtio channels will have been already marked NOT ready, causing any * outstanding message on any vqueue to be ignored by complete_cb: now * we can just stop processing buffers and destroy the vqueues. */ virtio_reset_device(vdev); vdev->config->del_vqs(vdev); /* Ensure scmi_vdev is visible as NULL */ smp_store_mb(scmi_vdev, NULL); } static int scmi_vio_validate(struct virtio_device *vdev) { #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO_VERSION1_COMPLIANCE if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) { dev_err(&vdev->dev, "device does not comply with spec version 1.x\n"); return -EINVAL; } #endif return 0; } static unsigned int features[] = { VIRTIO_SCMI_F_P2A_CHANNELS, }; static const struct virtio_device_id id_table[] = { { VIRTIO_ID_SCMI, VIRTIO_DEV_ANY_ID }, { 0 } }; static struct virtio_driver virtio_scmi_driver = { .driver.name = "scmi-virtio", .feature_table = features, .feature_table_size = ARRAY_SIZE(features), .id_table = id_table, .probe = scmi_vio_probe, .remove = scmi_vio_remove, .validate = scmi_vio_validate, }; static int __init virtio_scmi_init(void) { return register_virtio_driver(&virtio_scmi_driver); } static void virtio_scmi_exit(void) { unregister_virtio_driver(&virtio_scmi_driver); } const struct scmi_desc scmi_virtio_desc = { .transport_init = virtio_scmi_init, .transport_exit = virtio_scmi_exit, .ops = &scmi_virtio_ops, /* for non-realtime virtio devices */ .max_rx_timeout_ms = VIRTIO_MAX_RX_TIMEOUT_MS, .max_msg = 0, /* overridden by virtio_get_max_msg() */ .max_msg_size = VIRTIO_SCMI_MAX_MSG_SIZE, .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_VIRTIO_ATOMIC_ENABLE), };
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