drivers: qcom: rpmh: add support for batch RPMH request

Platform drivers need make a lot of resource state requests at the same
time, say, at the start or end of an usecase. It can be quite
inefficient to send each request separately. Instead they can give the
RPMH library a batch of requests to be sent and wait on the whole
transaction to be complete.

rpmh_write_batch() is a blocking call that can be used to send multiple
RPMH command sets. Each RPMH command set is set asynchronously and the
API blocks until all the command sets are complete and receive their
tx_done callbacks.

Signed-off-by: Lina Iyer <[e-mail]>
Signed-off-by: Raju P.L.S.S.S.N <[e-mail]>
Reviewed-by: Matthias Kaehlcke <[e-mail]>
Signed-off-by: Andy Gross <[e-mail]>

drivers/soc/qcom/rpmh-internal.h

···
  * @cache: the list of cached requests
  * @cache_lock: synchronize access to the cache data
  * @dirty: was the cache updated since flush
+ * @batch_cache: Cache sleep and wake requests sent as batch
  */
 struct rpmh_ctrlr {
 	struct list_head cache;
 	spinlock_t cache_lock;
 	bool dirty;
+	struct list_head batch_cache;
 };
 
 /**

drivers/soc/qcom/rpmh-rsc.c

···
 
 	spin_lock_init(&drv->client.cache_lock);
 	INIT_LIST_HEAD(&drv->client.cache);
+	INIT_LIST_HEAD(&drv->client.batch_cache);
 
 	dev_set_drvdata(&pdev->dev, drv);
 

drivers/soc/qcom/rpmh.c

···
 	struct list_head list;
 };
 
+/**
+ * struct batch_cache_req - An entry in our batch catch
+ *
+ * @list: linked list obj
+ * @count: number of messages
+ * @rpm_msgs: the messages
+ */
+
+struct batch_cache_req {
+	struct list_head list;
+	int count;
+	struct rpmh_request rpm_msgs[];
+};
+
 static struct rpmh_ctrlr *get_rpmh_ctrlr(const struct device *dev)
 {
 	struct rsc_drv *drv = dev_get_drvdata(dev->parent);
···
 		dev_err(rpm_msg->dev, "RPMH TX fail in msg addr=%#x, err=%d\n",
 			rpm_msg->msg.cmds[0].addr, r);
 
-	/* Signal the blocking thread we are done */
-	if (compl)
-		complete(compl);
+	if (!compl)
+		goto exit;
 
+	/* Signal the blocking thread we are done */
+	complete(compl);
+
+exit:
 	if (rpm_msg->needs_free)
 		kfree(rpm_msg);
 }
···
 }
 EXPORT_SYMBOL(rpmh_write);
 
+static void cache_batch(struct rpmh_ctrlr *ctrlr, struct batch_cache_req *req)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrlr->cache_lock, flags);
+	list_add_tail(&req->list, &ctrlr->batch_cache);
+	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+}
+
+static int flush_batch(struct rpmh_ctrlr *ctrlr)
+{
+	struct batch_cache_req *req;
+	const struct rpmh_request *rpm_msg;
+	unsigned long flags;
+	int ret = 0;
+	int i;
+
+	/* Send Sleep/Wake requests to the controller, expect no response */
+	spin_lock_irqsave(&ctrlr->cache_lock, flags);
+	list_for_each_entry(req, &ctrlr->batch_cache, list) {
+		for (i = 0; i < req->count; i++) {
+			rpm_msg = req->rpm_msgs + i;
+			ret = rpmh_rsc_write_ctrl_data(ctrlr_to_drv(ctrlr),
+						       &rpm_msg->msg);
+			if (ret)
+				break;
+		}
+	}
+	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+
+	return ret;
+}
+
+static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
+{
+	struct batch_cache_req *req, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrlr->cache_lock, flags);
+	list_for_each_entry_safe(req, tmp, &ctrlr->batch_cache, list)
+		kfree(req);
+	INIT_LIST_HEAD(&ctrlr->batch_cache);
+	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+}
+
+/**
+ * rpmh_write_batch: Write multiple sets of RPMH commands and wait for the
+ * batch to finish.
+ *
+ * @dev: the device making the request
+ * @state: Active/sleep set
+ * @cmd: The payload data
+ * @n: The array of count of elements in each batch, 0 terminated.
+ *
+ * Write a request to the RSC controller without caching. If the request
+ * state is ACTIVE, then the requests are treated as completion request
+ * and sent to the controller immediately. The function waits until all the
+ * commands are complete. If the request was to SLEEP or WAKE_ONLY, then the
+ * request is sent as fire-n-forget and no ack is expected.
+ *
+ * May sleep. Do not call from atomic contexts for ACTIVE_ONLY requests.
+ */
+int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
+		     const struct tcs_cmd *cmd, u32 *n)
+{
+	struct batch_cache_req *req;
+	struct rpmh_request *rpm_msgs;
+	DECLARE_COMPLETION_ONSTACK(compl);
+	struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
+	unsigned long time_left;
+	int count = 0;
+	int ret, i, j;
+
+	if (!cmd || !n)
+		return -EINVAL;
+
+	while (n[count] > 0)
+		count++;
+	if (!count)
+		return -EINVAL;
+
+	req = kzalloc(sizeof(*req) + count * sizeof(req->rpm_msgs[0]),
+		      GFP_ATOMIC);
+	if (!req)
+		return -ENOMEM;
+	req->count = count;
+	rpm_msgs = req->rpm_msgs;
+
+	for (i = 0; i < count; i++) {
+		__fill_rpmh_msg(rpm_msgs + i, state, cmd, n[i]);
+		cmd += n[i];
+	}
+
+	if (state != RPMH_ACTIVE_ONLY_STATE) {
+		cache_batch(ctrlr, req);
+		return 0;
+	}
+
+	for (i = 0; i < count; i++) {
+		rpm_msgs[i].completion = &compl;
+		ret = rpmh_rsc_send_data(ctrlr_to_drv(ctrlr), &rpm_msgs[i].msg);
+		if (ret) {
+			pr_err("Error(%d) sending RPMH message addr=%#x\n",
+			       ret, rpm_msgs[i].msg.cmds[0].addr);
+			for (j = i; j < count; j++)
+				rpmh_tx_done(&rpm_msgs[j].msg, ret);
+			break;
+		}
+	}
+
+	time_left = RPMH_TIMEOUT_MS;
+	for (i = 0; i < count; i++) {
+		time_left = wait_for_completion_timeout(&compl, time_left);
+		if (!time_left) {
+			/*
+			 * Better hope they never finish because they'll signal
+			 * the completion on our stack and that's bad once
+			 * we've returned from the function.
+			 */
+			WARN_ON(1);
+			ret = -ETIMEDOUT;
+			goto exit;
+		}
+	}
+
+exit:
+	kfree(req);
+
+	return ret;
+}
+EXPORT_SYMBOL(rpmh_write_batch);
+
 static int is_req_valid(struct cache_req *req)
 {
 	return (req->sleep_val != UINT_MAX &&
···
 		return 0;
 	}
 
+	/* First flush the cached batch requests */
+	ret = flush_batch(ctrlr);
+	if (ret)
+		return ret;
+
 	/*
 	 * Nobody else should be calling this function other than system PM,
 	 * hence we can run without locks.
···
 	struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
 	int ret;
 
+	invalidate_batch(ctrlr);
 	ctrlr->dirty = true;
 
 	do {

include/soc/qcom/rpmh.h

···
 int rpmh_write_async(const struct device *dev, enum rpmh_state state,
 		     const struct tcs_cmd *cmd, u32 n);
 
+int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
+		     const struct tcs_cmd *cmd, u32 *n);
+
 int rpmh_flush(const struct device *dev);
 
 int rpmh_invalidate(const struct device *dev);
···
 static inline int rpmh_write_async(const struct device *dev,
 				   enum rpmh_state state,
 				   const struct tcs_cmd *cmd, u32 n)
+{ return -ENODEV; }
+
+static inline int rpmh_write_batch(const struct device *dev,
+				   enum rpmh_state state,
+				   const struct tcs_cmd *cmd, u32 *n)
 { return -ENODEV; }
 
 static inline int rpmh_flush(const struct device *dev)