soc: qcom: glink: Add RX intent request timeout to G-Link channels

During glink_tx(), G-Link can wait for an unlimited amount of time for
the remote side to queue an RX intent. In some cases, e.g. SSR, the wait
must be restricted to a short time, but in the current implementation,
glink_tx() can continue to block indefinitely.

Add a configurable timeout value to the G-Link channel context, which is
set in the channel open configuration. If the value is set to 0, treat
it as an infinite timeout. This allows a timeout to be put in place by
the client for sensitive cases such as SSR where a very limited amount of
time can be spent waiting for an intent.

Change-Id: I1e480fac286d285f871fe3059de7ae761fc4581e
Signed-off-by: Steven Cahail <scahail@codeaurora.org>

drivers/soc/qcom/glink.c

@@ -159,14 +159,16 @@ struct glink_core_xprt_ctx {
  * @notify_rx_tracer_pkt:	Receive notification for tracer packet
  * @notify_remote_rx_intent:	Receive notification for remote-queued RX intent
  *
- * @transport_ptr:	Transport this channel uses
- * @lcid:		Local channel ID
- * @rcid:		Remote channel ID
- * @local_open_state:	Local channel state
- * @remote_opened:	Remote channel state (opened or closed)
- * @int_req_ack:	Remote side intent request ACK state
- * @int_req_ack_complete: Intent tracking completion - received remote ACK
- * @int_req_complete:	Intent tracking completion - received intent
+ * @transport_ptr:		Transport this channel uses
+ * @lcid:			Local channel ID
+ * @rcid:			Remote channel ID
+ * @local_open_state:		Local channel state
+ * @remote_opened:		Remote channel state (opened or closed)
+ * @int_req_ack:		Remote side intent request ACK state
+ * @int_req_ack_complete:	Intent tracking completion - received remote ACK
+ * @int_req_complete:		Intent tracking completion - received intent
+ * @rx_intent_req_timeout_jiffies:	Timeout for requesting an RX intent, in
+ *			jiffies; if set to 0, timeout is infinite
  *
  * @local_rx_intent_lst_lock_lhc1:	RX intent list lock
  * @local_rx_intent_list:		Active RX Intents queued by client
@@ -244,6 +246,7 @@ struct channel_ctx {
 	bool int_req_ack;
 	struct completion int_req_ack_complete;
 	struct completion int_req_complete;
+	unsigned long rx_intent_req_timeout_jiffies;
 
 	spinlock_t local_rx_intent_lst_lock_lhc1;
 	struct list_head local_rx_intent_list;
@@ -2401,6 +2404,8 @@ void *glink_open(const struct glink_open_config *cfg)
 
 	/* initialize port structure */
 	ctx->user_priv = cfg->priv;
+	ctx->rx_intent_req_timeout_jiffies =
+		msecs_to_jiffies(cfg->rx_intent_req_timeout_ms);
 	ctx->notify_rx = cfg->notify_rx;
 	ctx->notify_tx_done = cfg->notify_tx_done;
 	ctx->notify_state = cfg->notify_state;
@@ -2421,6 +2426,9 @@ void *glink_open(const struct glink_open_config *cfg)
 	if (!ctx->notify_tx_abort)
 		ctx->notify_tx_abort = glink_dummy_notify_tx_abort;
 
+	if (!ctx->rx_intent_req_timeout_jiffies)
+		ctx->rx_intent_req_timeout_jiffies = MAX_SCHEDULE_TIMEOUT;
+
 	ctx->local_xprt_req = best_id;
 	ctx->no_migrate = cfg->transport &&
 				!(cfg->options & GLINK_OPT_INITIAL_XPORT);
@@ -2712,7 +2720,16 @@ static int glink_tx_common(void *handle, void *pkt_priv,
 			}
 
 			/* wait for the remote intent req ack */
-			wait_for_completion(&ctx->int_req_ack_complete);
+			if (!wait_for_completion_timeout(
+					&ctx->int_req_ack_complete,
+					ctx->rx_intent_req_timeout_jiffies)) {
+				GLINK_ERR_CH(ctx,
+					"%s: Intent request ack with size: %zu not granted for lcid\n",
+					__func__, size);
+				rwref_put(&ctx->ch_state_lhc0);
+				return -ETIMEDOUT;
+			}
+
 			if (!ctx->int_req_ack) {
 				GLINK_ERR_CH(ctx,
 				    "%s: Intent Request with size: %zu %s",
@@ -2723,7 +2740,16 @@ static int glink_tx_common(void *handle, void *pkt_priv,
 			}
 
 			/* wait for the rx_intent from remote side */
-			wait_for_completion(&ctx->int_req_complete);
+			if (!wait_for_completion_timeout(
+					&ctx->int_req_complete,
+					ctx->rx_intent_req_timeout_jiffies)) {
+				GLINK_ERR_CH(ctx,
+					"%s: Intent request with size: %zu not granted for lcid\n",
+					__func__, size);
+				rwref_put(&ctx->ch_state_lhc0);
+				return -ETIMEDOUT;
+			}
+
 			reinit_completion(&ctx->int_req_complete);
 			ch_st = ctx->local_open_state;
 			if (ch_st == GLINK_CHANNEL_CLOSING ||

include/soc/qcom/glink.h

@@ -43,15 +43,17 @@ enum {
 /**
  * Open configuration.
  *
- * priv:	Private data passed into user callbacks
- * options:	Open option flags
- * notify_rx:	Receive notification function (required)
- * notify_tx_done: Transmit-done notification function (required)
- * notify_state: State-change notification (required)
- * notify_rx_intent_req: Receive intent request (optional)
- * notify_rxv:	Receive notification function for vector buffers (required if
- *		notify_rx is not provided)
- * notify_sig:	Signal-change notification (optional)
+ * priv:			Private data passed into user callbacks
+ * options:			Open option flags
+ * rx_intent_req_timeout_ms:	Timeout for requesting an RX intent, in
+ *			milliseconds; if set to 0, timeout is infinite
+ * notify_rx:			Receive notification function (required)
+ * notify_tx_done:		Transmit-done notification function (required)
+ * notify_state:		State-change notification (required)
+ * notify_rx_intent_req:	Receive intent request (optional)
+ * notify_rxv:			Receive notification function for vector buffers
+ *			(required if notify_rx is not provided)
+ * notify_sig:			Signal-change notification (optional)
  * notify_rx_tracer_pkt:	Receive notification for tracer packet
  * notify_remote_rx_intent:	Receive notification for remote-queued RX intent
  *
@@ -67,6 +69,7 @@ struct glink_open_config {
 	const char *transport;
 	const char *edge;
 	const char *name;
+	unsigned int rx_intent_req_timeout_ms;
 
 	void (*notify_rx)(void *handle, const void *priv, const void *pkt_priv,
 			const void *ptr, size_t size);