diff options
| -rw-r--r-- | drivers/firmware/arm_scmi/virtio.c | 143 |
1 files changed, 92 insertions, 51 deletions
diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c index 97d7cf53b774..71b016d1a655 100644 --- a/drivers/firmware/arm_scmi/virtio.c +++ b/drivers/firmware/arm_scmi/virtio.c @@ -17,7 +17,9 @@ * 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> @@ -27,6 +29,7 @@ #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) @@ -39,23 +42,21 @@ * @cinfo: SCMI Tx or Rx channel * @free_list: List of unused scmi_vio_msg, maintained for Tx channels only * @is_rx: Whether channel is an Rx channel - * @ready: Whether transport user is ready to hear about channel * @max_msg: Maximum number of pending messages for this channel. - * @lock: Protects access to all members except ready. - * @ready_lock: Protects access to ready. If required, it must be taken before - * lock. + * @lock: Protects access to all members except users. + * @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; struct list_head free_list; bool is_rx; - bool ready; unsigned int max_msg; - /* lock to protect access to all members except ready. */ + /* lock to protect access to all members except users. */ spinlock_t lock; - /* lock to rotects access to ready flag. */ - spinlock_t ready_lock; + struct completion *shutdown_done; + refcount_t users; }; /** @@ -76,6 +77,63 @@ struct scmi_vio_msg { /* 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; + virtio_break_device(vioch->vqueue->vdev); + 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); +} + static bool scmi_vio_have_vq_rx(struct virtio_device *vdev) { return virtio_has_feature(vdev, VIRTIO_SCMI_F_P2A_CHANNELS); @@ -119,7 +177,7 @@ static void scmi_finalize_message(struct scmi_vio_channel *vioch, static void scmi_vio_complete_cb(struct virtqueue *vqueue) { - unsigned long ready_flags; + unsigned long flags; unsigned int length; struct scmi_vio_channel *vioch; struct scmi_vio_msg *msg; @@ -130,27 +188,24 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue) vioch = &((struct scmi_vio_channel *)vqueue->vdev->priv)[vqueue->index]; for (;;) { - spin_lock_irqsave(&vioch->ready_lock, ready_flags); - - if (!vioch->ready) { - if (!cb_enabled) - (void)virtqueue_enable_cb(vqueue); - goto unlock_ready_out; - } + if (!scmi_vio_channel_acquire(vioch)) + return; - /* IRQs already disabled here no need to irqsave */ - spin_lock(&vioch->lock); + 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)) - goto unlock_out; + if (virtqueue_enable_cb(vqueue)) { + spin_unlock_irqrestore(&vioch->lock, flags); + scmi_vio_channel_release(vioch); + return; + } cb_enabled = true; } - spin_unlock(&vioch->lock); + spin_unlock_irqrestore(&vioch->lock, flags); if (msg) { msg->rx_len = length; @@ -161,19 +216,14 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue) } /* - * Release ready_lock and re-enable IRQs between loop iterations - * to allow virtio_chan_free() to possibly kick in and set the - * flag vioch->ready to false even in between processing of - * messages, so as to force outstanding messages to be ignored - * when system is shutting down. + * 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. */ - spin_unlock_irqrestore(&vioch->ready_lock, ready_flags); + scmi_vio_channel_release(vioch); } - -unlock_out: - spin_unlock(&vioch->lock); -unlock_ready_out: - spin_unlock_irqrestore(&vioch->ready_lock, ready_flags); } static const char *const scmi_vio_vqueue_names[] = { "tx", "rx" }; @@ -273,35 +323,20 @@ static int virtio_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, } } - 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); - - spin_lock_irqsave(&vioch->ready_lock, flags); - vioch->ready = true; - spin_unlock_irqrestore(&vioch->ready_lock, flags); + scmi_vio_channel_ready(vioch, cinfo); return 0; } static int virtio_chan_free(int id, void *p, void *data) { - unsigned long flags; struct scmi_chan_info *cinfo = p; struct scmi_vio_channel *vioch = cinfo->transport_info; - spin_lock_irqsave(&vioch->ready_lock, flags); - vioch->ready = false; - spin_unlock_irqrestore(&vioch->ready_lock, flags); + scmi_vio_channel_cleanup_sync(vioch); scmi_free_channel(cinfo, data, id); - spin_lock_irqsave(&vioch->lock, flags); - vioch->cinfo = NULL; - spin_unlock_irqrestore(&vioch->lock, flags); - return 0; } @@ -316,10 +351,14 @@ static int virtio_send_message(struct scmi_chan_info *cinfo, int rc; struct scmi_vio_msg *msg; + if (!scmi_vio_channel_acquire(vioch)) + return -EINVAL; + spin_lock_irqsave(&vioch->lock, flags); if (list_empty(&vioch->free_list)) { spin_unlock_irqrestore(&vioch->lock, flags); + scmi_vio_channel_release(vioch); return -EBUSY; } @@ -342,6 +381,8 @@ static int virtio_send_message(struct scmi_chan_info *cinfo, spin_unlock_irqrestore(&vioch->lock, flags); + scmi_vio_channel_release(vioch); + return rc; } @@ -416,7 +457,6 @@ static int scmi_vio_probe(struct virtio_device *vdev) unsigned int sz; spin_lock_init(&channels[i].lock); - spin_lock_init(&channels[i].ready_lock); INIT_LIST_HEAD(&channels[i].free_list); channels[i].vqueue = vqs[i]; @@ -503,7 +543,8 @@ const struct scmi_desc scmi_virtio_desc = { .transport_init = virtio_scmi_init, .transport_exit = virtio_scmi_exit, .ops = &scmi_virtio_ops, - .max_rx_timeout_ms = 60000, /* for non-realtime virtio devices */ + /* 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, }; |