pm: EDP: loan handling

Added EDP loan APIs and single-borrower implementation.

Change-Id: Ib4c3777d7173d16d5d002fd28e8f74f1b6add239
Signed-off-by: Sivaram Nair <sivaramn@nvidia.com>
Reviewed-on: http://git-master/r/115713
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>
Reviewed-by: Juha Tukkinen <jtukkinen@nvidia.com>
Reviewed-by: Peter De Schrijver <pdeschrijver@nvidia.com>

1 files changed, 199 insertions, 7 deletions

diff --git a/drivers/edp/edp.c b/drivers/edp/edp.c
index 63a7df1b3f10..900c2289adc6 100644
--- a/drivers/edp/edp.c
+++ b/drivers/edp/edp.c
@@ -21,8 +21,15 @@
 #include <linux/string.h>
 #include <linux/mutex.h>
 #include <linux/errno.h>
+#include <linux/slab.h>
 #include <linux/edp.h>
 
+struct loan_client {
+	struct list_head link;
+	struct edp_client *client;
+	unsigned int size;
+};
+
 DEFINE_MUTEX(edp_lock);
 static LIST_HEAD(edp_managers);
 
@@ -159,6 +166,10 @@ static int register_client(struct edp_manager *mgr, struct edp_client *client)
 	client->manager = mgr;
 	client->req = NULL;
 	client->cur = NULL;
+	INIT_LIST_HEAD(&client->borrowers);
+	client->num_borrowers = 0;
+	client->num_loans = 0;
+	client->ithreshold = client->states[0];
 
 	return 0;
 }
@@ -175,6 +186,32 @@ int edp_register_client(struct edp_manager *mgr, struct edp_client *client)
 }
 EXPORT_SYMBOL(edp_register_client);
 
+static void update_loans(struct edp_client *client)
+{
+	struct loan_client *p;
+	unsigned int size;
+
+	if (!client->cur || list_empty(&client->borrowers))
+		return;
+
+	size = *client->cur < client->ithreshold ? 0 :
+		*client->cur - client->ithreshold;
+
+	/* TODO: multi-party loans */
+	if (!list_is_singular(&client->borrowers)) {
+		WARN_ON(1);
+		return;
+	}
+
+	p = list_first_entry(&client->borrowers, struct loan_client, link);
+
+	/* avoid spurious change notifications */
+	if (size != p->size) {
+		p->size = size;
+		p->client->notify_loan_update(size, client);
+	}
+}
+
 static int mod_request(struct edp_client *client, const unsigned int *req)
 {
 	unsigned int old = client->cur ? *client->cur : 0;
@@ -192,17 +229,45 @@ static int mod_request(struct edp_client *client, const unsigned int *req)
 		client->cur = req;
 	}
 
+	update_loans(client);
+
 	return 0;
 }
 
+static void del_borrower(struct edp_client *lender, struct loan_client *pcl)
+{
+	pcl->client->notify_loan_close(lender);
+	lender->num_borrowers--;
+	pcl->client->num_loans--;
+	list_del(&pcl->link);
+	kfree(pcl);
+}
+
+static void close_all_loans(struct edp_client *client)
+{
+	struct loan_client *p;
+
+	while (!list_empty(&client->borrowers)) {
+		p = list_first_entry(&client->borrowers, struct loan_client,
+				link);
+		del_borrower(client, p);
+	}
+}
+
+static inline bool registered_client(struct edp_client *client)
+{
+	return client ? client->manager : false;
+}
+
 static int unregister_client(struct edp_client *client)
 {
-	if (!client)
+	if (!registered_client(client))
 		return -EINVAL;
 
-	if (!client->manager)
-		return -ENODEV;
+	if (client->num_loans)
+		return -EBUSY;
 
+	close_all_loans(client);
 	mod_request(client, NULL);
 	list_del(&client->link);
 	client->manager = NULL;
@@ -227,12 +292,9 @@ static int update_client_request(struct edp_client *client, unsigned int req,
 {
 	int r;
 
-	if (!client)
+	if (!registered_client(client))
 		return -EINVAL;
 
-	if (!client->manager)
-		return -ENODEV;
-
 	if (req >= client->num_states)
 		return -EINVAL;
 
@@ -255,3 +317,133 @@ int edp_update_client_request(struct edp_client *client, unsigned int req,
 	return r;
 }
 EXPORT_SYMBOL(edp_update_client_request);
+
+static struct edp_client *get_client(const char *name)
+{
+	struct edp_client *client;
+	struct edp_manager *mgr;
+
+	if (!name)
+		return NULL;
+
+	list_for_each_entry(mgr, &edp_managers, link) {
+		client = find_client(mgr, name);
+		if (client)
+			return client;
+	}
+
+	return NULL;
+}
+
+struct edp_client *edp_get_client(const char *name)
+{
+	struct edp_client *client;
+
+	mutex_lock(&edp_lock);
+	client = get_client(name);
+	mutex_unlock(&edp_lock);
+
+	return client;
+}
+EXPORT_SYMBOL(edp_get_client);
+
+static struct loan_client *find_borrower(struct edp_client *lender,
+		struct edp_client *borrower)
+{
+	struct loan_client *p;
+
+	list_for_each_entry(p, &lender->borrowers, link)
+		if (p->client == borrower)
+			return p;
+	return NULL;
+}
+
+static int register_loan(struct edp_client *lender, struct edp_client *borrower)
+{
+	struct loan_client *p;
+
+	if (!registered_client(lender) || !registered_client(borrower))
+		return -EINVAL;
+
+	if (lender->manager != borrower->manager ||
+			!borrower->notify_loan_update ||
+			!borrower->notify_loan_close)
+		return -EINVAL;
+
+	if (find_borrower(lender, borrower))
+		return -EEXIST;
+
+	if (lender->num_borrowers >= lender->max_borrowers)
+		return -EBUSY;
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	p->client = borrower;
+	lender->num_borrowers++;
+	borrower->num_loans++;
+	list_add_tail(&p->link, &lender->borrowers);
+
+	update_loans(lender);
+	return 0;
+}
+
+int edp_register_loan(struct edp_client *lender, struct edp_client *borrower)
+{
+	int r;
+
+	mutex_lock(&edp_lock);
+	r = register_loan(lender, borrower);
+	mutex_unlock(&edp_lock);
+
+	return r;
+}
+EXPORT_SYMBOL(edp_register_loan);
+
+static int unregister_loan(struct edp_client *lender,
+		struct edp_client *borrower)
+{
+	struct loan_client *p;
+
+	if (!registered_client(lender) || !registered_client(borrower))
+		return -EINVAL;
+
+	p = find_borrower(lender, borrower);
+	if (!p)
+		return -EINVAL;
+
+	del_borrower(lender, p);
+	update_loans(lender);
+	return 0;
+}
+
+int edp_unregister_loan(struct edp_client *lender, struct edp_client *borrower)
+{
+	int r;
+
+	mutex_lock(&edp_lock);
+	r = unregister_loan(lender, borrower);
+	mutex_unlock(&edp_lock);
+
+	return r;
+}
+EXPORT_SYMBOL(edp_unregister_loan);
+
+int edp_update_loan_threshold(struct edp_client *client, unsigned int threshold)
+{
+	int r = -EINVAL;
+
+	mutex_lock(&edp_lock);
+
+	if (registered_client(client)) {
+		client->ithreshold = threshold;
+		update_loans(client);
+		r = 0;
+	}
+
+	mutex_unlock(&edp_lock);
+
+	return r;
+}
+EXPORT_SYMBOL(edp_update_loan_threshold);