source "drivers/firmware/arm_scmi/transports/Kconfig"
-config ARM_SCMI_TRANSPORT_VIRTIO
- bool "SCMI transport based on VirtIO"
- depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL
- select ARM_SCMI_HAVE_TRANSPORT
- select ARM_SCMI_HAVE_MSG
- help
- This enables the virtio based transport for SCMI.
-
- If you want the ARM SCMI PROTOCOL stack to include support for a
- transport based on VirtIO, answer Y.
-
-config ARM_SCMI_TRANSPORT_VIRTIO_VERSION1_COMPLIANCE
- bool "SCMI VirtIO transport Version 1 compliance"
- depends on ARM_SCMI_TRANSPORT_VIRTIO
- default y
- help
- This enforces strict compliance with VirtIO Version 1 specification.
-
- If you want the ARM SCMI VirtIO transport layer to refuse to work
- with Legacy VirtIO backends and instead support only VirtIO Version 1
- devices (or above), answer Y.
-
- If you want instead to support also old Legacy VirtIO backends (like
- the ones implemented by kvmtool) and let the core Kernel VirtIO layer
- take care of the needed conversions, say N.
-
-config ARM_SCMI_TRANSPORT_VIRTIO_ATOMIC_ENABLE
- bool "Enable atomic mode for SCMI VirtIO transport"
- depends on ARM_SCMI_TRANSPORT_VIRTIO
- help
- Enable support of atomic operation for SCMI VirtIO based transport.
-
- If you want the SCMI VirtIO based transport to operate in atomic
- mode, avoiding any kind of sleeping behaviour for selected
- transactions on the TX path, answer Y.
-
- Enabling atomic mode operations allows any SCMI driver using this
- transport to optionally ask for atomic SCMI transactions and operate
- in atomic context too, at the price of using a number of busy-waiting
- primitives all over instead. If unsure say N.
-
endif #ARM_SCMI_PROTOCOL
config ARM_SCMI_POWER_CONTROL
scmi-driver-$(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT) += raw_mode.o
scmi-transport-$(CONFIG_ARM_SCMI_HAVE_SHMEM) = shmem.o
scmi-transport-$(CONFIG_ARM_SCMI_HAVE_MSG) += msg.o
-scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_VIRTIO) += virtio.o
scmi-protocols-y := base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.o powercap.o
scmi-protocols-y += pinctrl.o
scmi-module-objs := $(scmi-driver-y) $(scmi-protocols-y) $(scmi-transport-y)
int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
struct scmi_xfer *xfer,
unsigned int timeout_ms);
-#ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
-extern const struct scmi_desc scmi_virtio_desc;
-#endif
void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr, void *priv);
/* Each compatible listed below must have descriptor associated with it */
static const struct of_device_id scmi_of_match[] = {
-#ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
- { .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
-#endif
{ /* Sentinel */ },
};
This driver can also be built as a module. If so, the module
will be called scmi_transport_optee.
+config ARM_SCMI_TRANSPORT_VIRTIO
+ tristate "SCMI transport based on VirtIO"
+ depends on VIRTIO
+ select ARM_SCMI_HAVE_TRANSPORT
+ select ARM_SCMI_HAVE_MSG
+ help
+ This enables the virtio based transport for SCMI.
+
+ If you want the ARM SCMI PROTOCOL stack to include support for a
+ transport based on VirtIO, answer Y.
+ This driver can also be built as a module. If so, the module
+ will be called scmi_transport_virtio.
+
+config ARM_SCMI_TRANSPORT_VIRTIO_VERSION1_COMPLIANCE
+ bool "SCMI VirtIO transport Version 1 compliance"
+ depends on ARM_SCMI_TRANSPORT_VIRTIO
+ default y
+ help
+ This enforces strict compliance with VirtIO Version 1 specification.
+
+ If you want the ARM SCMI VirtIO transport layer to refuse to work
+ with Legacy VirtIO backends and instead support only VirtIO Version 1
+ devices (or above), answer Y.
+
+ If you want instead to support also old Legacy VirtIO backends (like
+ the ones implemented by kvmtool) and let the core Kernel VirtIO layer
+ take care of the needed conversions, say N.
+
+config ARM_SCMI_TRANSPORT_VIRTIO_ATOMIC_ENABLE
+ bool "Enable atomic mode for SCMI VirtIO transport"
+ depends on ARM_SCMI_TRANSPORT_VIRTIO
+ help
+ Enable support of atomic operation for SCMI VirtIO based transport.
+
+ If you want the SCMI VirtIO based transport to operate in atomic
+ mode, avoiding any kind of sleeping behaviour for selected
+ transactions on the TX path, answer Y.
+
+ Enabling atomic mode operations allows any SCMI driver using this
+ transport to optionally ask for atomic SCMI transactions and operate
+ in atomic context too, at the price of using a number of busy-waiting
+ primitives all over instead. If unsure say N.
+
endmenu
obj-$(CONFIG_ARM_SCMI_TRANSPORT_SMC) += scmi_transport_smc.o
scmi_transport_optee-objs := optee.o
obj-$(CONFIG_ARM_SCMI_TRANSPORT_OPTEE) += scmi_transport_optee.o
+scmi_transport_virtio-objs := virtio.o
+obj-$(CONFIG_ARM_SCMI_TRANSPORT_VIRTIO) += scmi_transport_virtio.o
ifeq ($(CONFIG_THUMB2_KERNEL)$(CONFIG_CC_IS_CLANG),yy)
# The use of R7 in the SMCCC conflicts with the compiler's use of R7 as a frame
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Virtio Transport driver for Arm System Control and Management Interface
+ * (SCMI).
+ *
+ * Copyright (C) 2020-2022 OpenSynergy.
+ * Copyright (C) 2021-2024 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/platform_device.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;
+};
+
+static struct scmi_transport_core_operations *core;
+
+/* 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;
+ core->rx_callback(vioch->cinfo,
+ core->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)
+ core->rx_callback(vioch->cinfo,
+ core->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 struct virtqueue_info scmi_vio_vqs_info[] = {
+ { "tx", scmi_vio_complete_cb },
+ { "rx", 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 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;
+ }
+
+ core->msg->tx_prepare(msg->request, xfer);
+
+ sg_init_one(&sg_out, msg->request, core->msg->command_size(xfer));
+ sg_init_one(&sg_in, msg->input, core->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)
+ core->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)
+ core->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 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 = {
+ .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 const struct scmi_desc scmi_virtio_desc = {
+ .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),
+};
+
+static const struct of_device_id scmi_of_match[] = {
+ { .compatible = "arm,scmi-virtio" },
+ { /* Sentinel */ },
+};
+
+DEFINE_SCMI_TRANSPORT_DRIVER(scmi_virtio, scmi_virtio_driver, scmi_virtio_desc,
+ scmi_of_match, core);
+
+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_vqs_info, 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);
+
+ ret = platform_driver_register(&scmi_virtio_driver);
+ if (ret) {
+ vdev->priv = NULL;
+ vdev->config->del_vqs(vdev);
+ /* Ensure NULLified scmi_vdev is visible */
+ smp_store_mb(scmi_vdev, NULL);
+
+ return ret;
+ }
+
+ return 0;
+}
+
+static void scmi_vio_remove(struct virtio_device *vdev)
+{
+ platform_driver_unregister(&scmi_virtio_driver);
+
+ /*
+ * 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,
+};
+
+module_virtio_driver(virtio_scmi_driver);
+
+MODULE_AUTHOR("Igor Skalkin <igor.skalkin@opensynergy.com>");
+MODULE_AUTHOR("Peter Hilber <peter.hilber@opensynergy.com>");
+MODULE_AUTHOR("Cristian Marussi <cristian.marussi@arm.com>");
+MODULE_DESCRIPTION("SCMI VirtIO Transport driver");
+MODULE_LICENSE("GPL");
+++ /dev/null
-// 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,
- scmi_msg_ops.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,
- scmi_msg_ops.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 struct virtqueue_info scmi_vio_vqs_info[] = {
- { "tx", scmi_vio_complete_cb },
- { "rx", 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;
- }
-
- scmi_msg_ops.tx_prepare(msg->request, xfer);
-
- sg_init_one(&sg_out, msg->request, scmi_msg_ops.command_size(xfer));
- sg_init_one(&sg_in, msg->input, scmi_msg_ops.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)
- scmi_msg_ops.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)
- scmi_msg_ops.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_vqs_info, 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),
-};
projects / linux-block.git / commitdiff