nfp: add async version of mailbox communication

Some control messages must be sent from atomic context.  The mailbox
takes sleeping locks and uses a waitqueue so add a "posted" version
of communication.

Trylock the semaphore and if that's successful kick of the device
communication.  The device communication will be completed from
a workqueue, which will also release the semaphore.

If locks are taken queue the message and return.  Schedule a
different workqueue to take the semaphore and run the communication.
Note that the there are currently no atomic users which would actually
need the return value, so all replies to posted messages are just
freed.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 159 insertions, 16 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/ccm_mbox.c b/drivers/net/ethernet/netronome/nfp/ccm_mbox.c
index 53995d53aa3f..02fccd90961d 100644
--- a/drivers/net/ethernet/netronome/nfp/ccm_mbox.c
+++ b/drivers/net/ethernet/netronome/nfp/ccm_mbox.c
@@ -41,12 +41,14 @@ enum nfp_net_mbox_cmsg_state {
  * @err:	error encountered during processing if any
  * @max_len:	max(request_len, reply_len)
  * @exp_reply:	expected reply length (0 means don't validate)
+ * @posted:	the message was posted and nobody waits for the reply
  */
 struct nfp_ccm_mbox_cmsg_cb {
 	enum nfp_net_mbox_cmsg_state state;
 	int err;
 	unsigned int max_len;
 	unsigned int exp_reply;
+	bool posted;
 };
 
 static u32 nfp_ccm_mbox_max_msg(struct nfp_net *nn)
@@ -65,6 +67,7 @@ nfp_ccm_mbox_msg_init(struct sk_buff *skb, unsigned int exp_reply, int max_len)
 	cb->err = 0;
 	cb->max_len = max_len;
 	cb->exp_reply = exp_reply;
+	cb->posted = false;
 }
 
 static int nfp_ccm_mbox_maxlen(const struct sk_buff *skb)
@@ -96,6 +99,20 @@ static void nfp_ccm_mbox_set_busy(struct sk_buff *skb)
 	cb->state = NFP_NET_MBOX_CMSG_STATE_BUSY;
 }
 
+static bool nfp_ccm_mbox_is_posted(struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	return cb->posted;
+}
+
+static void nfp_ccm_mbox_mark_posted(struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	cb->posted = true;
+}
+
 static bool nfp_ccm_mbox_is_first(struct nfp_net *nn, struct sk_buff *skb)
 {
 	return skb_queue_is_first(&nn->mbox_cmsg.queue, skb);
@@ -119,6 +136,8 @@ static void nfp_ccm_mbox_mark_next_runner(struct nfp_net *nn)
 
 	cb = (void *)skb->cb;
 	cb->state = NFP_NET_MBOX_CMSG_STATE_NEXT;
+	if (cb->posted)
+		queue_work(nn->mbox_cmsg.workq, &nn->mbox_cmsg.runq_work);
 }
 
 static void
@@ -205,9 +224,7 @@ static void nfp_ccm_mbox_copy_out(struct nfp_net *nn, struct sk_buff *last)
 	while (true) {
 		unsigned int length, offset, type;
 		struct nfp_ccm_hdr hdr;
-		__be32 *skb_data;
 		u32 tlv_hdr;
-		int i, cnt;
 
 		tlv_hdr = readl(data);
 		type = FIELD_GET(NFP_NET_MBOX_TLV_TYPE, tlv_hdr);
@@ -278,20 +295,26 @@ static void nfp_ccm_mbox_copy_out(struct nfp_net *nn, struct sk_buff *last)
 			goto next_tlv;
 		}
 
-		if (length <= skb->len)
-			__skb_trim(skb, length);
-		else
-			skb_put(skb, length - skb->len);
-
-		/* We overcopy here slightly, but that's okay, the skb is large
-		 * enough, and the garbage will be ignored (beyond skb->len).
-		 */
-		skb_data = (__be32 *)skb->data;
-		memcpy(skb_data, &hdr, 4);
-
-		cnt = DIV_ROUND_UP(length, 4);
-		for (i = 1 ; i < cnt; i++)
-			skb_data[i] = cpu_to_be32(readl(data + i * 4));
+		if (!cb->posted) {
+			__be32 *skb_data;
+			int i, cnt;
+
+			if (length <= skb->len)
+				__skb_trim(skb, length);
+			else
+				skb_put(skb, length - skb->len);
+
+			/* We overcopy here slightly, but that's okay,
+			 * the skb is large enough, and the garbage will
+			 * be ignored (beyond skb->len).
+			 */
+			skb_data = (__be32 *)skb->data;
+			memcpy(skb_data, &hdr, 4);
+
+			cnt = DIV_ROUND_UP(length, 4);
+			for (i = 1 ; i < cnt; i++)
+				skb_data[i] = cpu_to_be32(readl(data + i * 4));
+		}
 
 		cb->state = NFP_NET_MBOX_CMSG_STATE_REPLY_FOUND;
 next_tlv:
@@ -314,6 +337,14 @@ next_tlv:
 			smp_wmb(); /* order the cb->err vs. cb->state */
 		}
 		cb->state = NFP_NET_MBOX_CMSG_STATE_DONE;
+
+		if (cb->posted) {
+			if (cb->err)
+				nn_dp_warn(&nn->dp,
+					   "mailbox posted msg failed type:%u err:%d\n",
+					   nfp_ccm_get_type(skb), cb->err);
+			dev_consume_skb_any(skb);
+		}
 	} while (skb != last);
 
 	nfp_ccm_mbox_mark_next_runner(nn);
@@ -563,6 +594,89 @@ err_free_skb:
 	return err;
 }
 
+static void nfp_ccm_mbox_post_runq_work(struct work_struct *work)
+{
+	struct sk_buff *skb;
+	struct nfp_net *nn;
+
+	nn = container_of(work, struct nfp_net, mbox_cmsg.runq_work);
+
+	spin_lock_bh(&nn->mbox_cmsg.queue.lock);
+
+	skb = __skb_peek(&nn->mbox_cmsg.queue);
+	if (WARN_ON(!skb || !nfp_ccm_mbox_is_posted(skb) ||
+		    !nfp_ccm_mbox_should_run(nn, skb))) {
+		spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+		return;
+	}
+
+	nfp_ccm_mbox_run_queue_unlock(nn);
+}
+
+static void nfp_ccm_mbox_post_wait_work(struct work_struct *work)
+{
+	struct sk_buff *skb;
+	struct nfp_net *nn;
+	int err;
+
+	nn = container_of(work, struct nfp_net, mbox_cmsg.wait_work);
+
+	skb = skb_peek(&nn->mbox_cmsg.queue);
+	if (WARN_ON(!skb || !nfp_ccm_mbox_is_posted(skb)))
+		/* Should never happen so it's unclear what to do here.. */
+		goto exit_unlock_wake;
+
+	err = nfp_net_mbox_reconfig_wait_posted(nn);
+	if (!err)
+		nfp_ccm_mbox_copy_out(nn, skb);
+	else
+		nfp_ccm_mbox_mark_all_err(nn, skb, -EIO);
+exit_unlock_wake:
+	nn_ctrl_bar_unlock(nn);
+	wake_up_all(&nn->mbox_cmsg.wq);
+}
+
+int nfp_ccm_mbox_post(struct nfp_net *nn, struct sk_buff *skb,
+		      enum nfp_ccm_type type, unsigned int max_reply_size)
+{
+	int err;
+
+	err = nfp_ccm_mbox_msg_prepare(nn, skb, type, 0, max_reply_size,
+				       GFP_ATOMIC);
+	if (err)
+		goto err_free_skb;
+
+	nfp_ccm_mbox_mark_posted(skb);
+
+	spin_lock_bh(&nn->mbox_cmsg.queue.lock);
+
+	err = nfp_ccm_mbox_msg_enqueue(nn, skb, type);
+	if (err)
+		goto err_unlock;
+
+	if (nfp_ccm_mbox_is_first(nn, skb)) {
+		if (nn_ctrl_bar_trylock(nn)) {
+			nfp_ccm_mbox_copy_in(nn, skb);
+			nfp_net_mbox_reconfig_post(nn,
+						   NFP_NET_CFG_MBOX_CMD_TLV_CMSG);
+			queue_work(nn->mbox_cmsg.workq,
+				   &nn->mbox_cmsg.wait_work);
+		} else {
+			nfp_ccm_mbox_mark_next_runner(nn);
+		}
+	}
+
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+
+	return 0;
+
+err_unlock:
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+err_free_skb:
+	dev_kfree_skb_any(skb);
+	return err;
+}
+
 struct sk_buff *
 nfp_ccm_mbox_msg_alloc(struct nfp_net *nn, unsigned int req_size,
 		       unsigned int reply_size, gfp_t flags)
@@ -589,3 +703,32 @@ bool nfp_ccm_mbox_fits(struct nfp_net *nn, unsigned int size)
 {
 	return nfp_ccm_mbox_max_msg(nn) >= size;
 }
+
+int nfp_ccm_mbox_init(struct nfp_net *nn)
+{
+	return 0;
+}
+
+void nfp_ccm_mbox_clean(struct nfp_net *nn)
+{
+	drain_workqueue(nn->mbox_cmsg.workq);
+}
+
+int nfp_ccm_mbox_alloc(struct nfp_net *nn)
+{
+	skb_queue_head_init(&nn->mbox_cmsg.queue);
+	init_waitqueue_head(&nn->mbox_cmsg.wq);
+	INIT_WORK(&nn->mbox_cmsg.wait_work, nfp_ccm_mbox_post_wait_work);
+	INIT_WORK(&nn->mbox_cmsg.runq_work, nfp_ccm_mbox_post_runq_work);
+
+	nn->mbox_cmsg.workq = alloc_workqueue("nfp-ccm-mbox", WQ_UNBOUND, 0);
+	if (!nn->mbox_cmsg.workq)
+		return -ENOMEM;
+	return 0;
+}
+
+void nfp_ccm_mbox_free(struct nfp_net *nn)
+{
+	destroy_workqueue(nn->mbox_cmsg.workq);
+	WARN_ON(!skb_queue_empty(&nn->mbox_cmsg.queue));
+}