2 files changed, 68 insertions, 58 deletions

diff --git a/drivers/hsi/hsi.c b/drivers/hsi/hsi.c
index cec1f0c04557..2d58f939d27f 100644
--- a/drivers/hsi/hsi.c
+++ b/drivers/hsi/hsi.c
@@ -21,12 +21,11 @@
  */
 #include <linux/hsi/hsi.h>
 #include <linux/compiler.h>
-#include <linux/rwsem.h>
 #include <linux/list.h>
-#include <linux/spinlock.h>
 #include <linux/kobject.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/notifier.h>
 #include "hsi_core.h"
 
 static ssize_t modalias_show(struct device *dev,
@@ -67,7 +66,6 @@ static void hsi_client_release(struct device *dev)
 static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
 {
         struct hsi_client *cl;
-        unsigned long flags;
 
         cl = kzalloc(sizeof(*cl), GFP_KERNEL);
         if (!cl)
@@ -79,9 +77,6 @@ static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
         cl->device.release = hsi_client_release;
         dev_set_name(&cl->device, info->name);
         cl->device.platform_data = info->platform_data;
-        spin_lock_irqsave(&port->clock, flags);
-        list_add_tail(&cl->link, &port->clients);
-        spin_unlock_irqrestore(&port->clock, flags);
         if (info->archdata)
                 cl->device.archdata = *info->archdata;
         if (device_register(&cl->device) < 0) {
@@ -106,13 +101,6 @@ static void hsi_scan_board_info(struct hsi_controller *hsi)
 
 static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
 {
-        struct hsi_client *cl = to_hsi_client(dev);
-        struct hsi_port *port = to_hsi_port(dev->parent);
-        unsigned long flags;
-
-        spin_lock_irqsave(&port->clock, flags);
-        list_del(&cl->link);
-        spin_unlock_irqrestore(&port->clock, flags);
         device_unregister(dev);
 
         return 0;
@@ -271,8 +259,7 @@ struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
                 port[i]->stop_tx = hsi_dummy_cl;
                 port[i]->release = hsi_dummy_cl;
                 mutex_init(&port[i]->lock);
-                INIT_LIST_HEAD(&hsi->port[i]->clients);
-                spin_lock_init(&hsi->port[i]->clock);
+                ATOMIC_INIT_NOTIFIER_HEAD(&port[i]->n_head);
                 dev_set_name(&port[i]->device, "port%d", i);
                 hsi->port[i]->device.release = hsi_port_release;
                 device_initialize(&hsi->port[i]->device);
@@ -420,37 +407,67 @@ void hsi_release_port(struct hsi_client *cl)
 }
 EXPORT_SYMBOL_GPL(hsi_release_port);
 
-static int hsi_start_rx(struct hsi_client *cl, void *data __maybe_unused)
+static int hsi_event_notifier_call(struct notifier_block *nb,
+                                unsigned long event, void *data __maybe_unused)
 {
-        if (cl->hsi_start_rx)
-                (*cl->hsi_start_rx)(cl);
+        struct hsi_client *cl = container_of(nb, struct hsi_client, nb);
+
+        (*cl->ehandler)(cl, event);
 
         return 0;
 }
 
-static int hsi_stop_rx(struct hsi_client *cl, void *data __maybe_unused)
+/**
+ * hsi_register_port_event - Register a client to receive port events
+ * @cl: HSI client that wants to receive port events
+ * @cb: Event handler callback
+ *
+ * Clients should register a callback to be able to receive
+ * events from the ports. Registration should happen after
+ * claiming the port.
+ * The handler can be called in interrupt context.
+ *
+ * Returns -errno on error, or 0 on success.
+ */
+int hsi_register_port_event(struct hsi_client *cl,
+                        void (*handler)(struct hsi_client *, unsigned long))
 {
-        if (cl->hsi_stop_rx)
-                (*cl->hsi_stop_rx)(cl);
+        struct hsi_port *port = hsi_get_port(cl);
 
-        return 0;
+        if (!handler || cl->ehandler)
+                return -EINVAL;
+        if (!hsi_port_claimed(cl))
+                return -EACCES;
+        cl->ehandler = handler;
+        cl->nb.notifier_call = hsi_event_notifier_call;
+
+        return atomic_notifier_chain_register(&port->n_head, &cl->nb);
 }
+EXPORT_SYMBOL_GPL(hsi_register_port_event);
 
-static int hsi_port_for_each_client(struct hsi_port *port, void *data,
-                                int (*fn)(struct hsi_client *cl, void *data))
+/**
+ * hsi_unregister_port_event - Stop receiving port events for a client
+ * @cl: HSI client that wants to stop receiving port events
+ *
+ * Clients should call this function before releasing their associated
+ * port.
+ *
+ * Returns -errno on error, or 0 on success.
+ */
+int hsi_unregister_port_event(struct hsi_client *cl)
 {
-        struct hsi_client *cl;
+        struct hsi_port *port = hsi_get_port(cl);
+        int err;
 
-        spin_lock(&port->clock);
-        list_for_each_entry(cl, &port->clients, link) {
-                spin_unlock(&port->clock);
-                (*fn)(cl, data);
-                spin_lock(&port->clock);
-        }
-        spin_unlock(&port->clock);
+        WARN_ON(!hsi_port_claimed(cl));
 
-        return 0;
+        err = atomic_notifier_chain_unregister(&port->n_head, &cl->nb);
+        if (!err)
+                cl->ehandler = NULL;
+
+        return err;
 }
+EXPORT_SYMBOL_GPL(hsi_unregister_port_event);
 
 /**
  * hsi_event -Notifies clients about port events
@@ -464,22 +481,12 @@ static int hsi_port_for_each_client(struct hsi_port *port, void *data,
  * Events:
  * HSI_EVENT_START_RX - Incoming wake line high
  * HSI_EVENT_STOP_RX - Incoming wake line down
+ *
+ * Returns -errno on error, or 0 on success.
  */
-void hsi_event(struct hsi_port *port, unsigned int event)
+int hsi_event(struct hsi_port *port, unsigned long event)
 {
-        int (*fn)(struct hsi_client *cl, void *data);
-
-        switch (event) {
-        case HSI_EVENT_START_RX:
-                fn = hsi_start_rx;
-                break;
-        case HSI_EVENT_STOP_RX:
-                fn = hsi_stop_rx;
-                break;
-        default:
-                return;
-        }
-        hsi_port_for_each_client(port, NULL, fn);
+        return atomic_notifier_call_chain(&port->n_head, event, NULL);
 }
 EXPORT_SYMBOL_GPL(hsi_event);
 
diff --git a/include/linux/hsi/hsi.h b/include/linux/hsi/hsi.h
index 7f3b7262a2b6..56fae865e272 100644
--- a/include/linux/hsi/hsi.h
+++ b/include/linux/hsi/hsi.h
@@ -26,9 +26,9 @@
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/scatterlist.h>
-#include <linux/spinlock.h>
 #include <linux/list.h>
 #include <linux/module.h>
+#include <linux/notifier.h>
 
 /* HSI message ttype */
 #define HSI_MSG_READ    0
@@ -121,18 +121,18 @@ static inline int hsi_register_board_info(struct hsi_board_info const *info,
  * @device: Driver model representation of the device
  * @tx_cfg: HSI TX configuration
  * @rx_cfg: HSI RX configuration
- * @hsi_start_rx: Called after incoming wake line goes high
- * @hsi_stop_rx: Called after incoming wake line goes low
+ * @e_handler: Callback for handling port events (RX Wake High/Low)
+ * @pclaimed: Keeps tracks if the clients claimed its associated HSI port
+ * @nb: Notifier block for port events
  */
 struct hsi_client {
         struct device           device;
         struct hsi_config       tx_cfg;
         struct hsi_config       rx_cfg;
-        void                    (*hsi_start_rx)(struct hsi_client *cl);
-        void                    (*hsi_stop_rx)(struct hsi_client *cl);
         /* private: */
+        void                    (*ehandler)(struct hsi_client *, unsigned long);
         unsigned int            pclaimed:1;
-        struct list_head        link;
+        struct notifier_block   nb;
 };
 
 #define to_hsi_client(dev) container_of(dev, struct hsi_client, device)
@@ -147,6 +147,10 @@ static inline void *hsi_client_drvdata(struct hsi_client *cl)
         return dev_get_drvdata(&cl->device);
 }
 
+int hsi_register_port_event(struct hsi_client *cl,
+                        void (*handler)(struct hsi_client *, unsigned long));
+int hsi_unregister_port_event(struct hsi_client *cl);
+
 /**
  * struct hsi_client_driver - Driver associated to an HSI client
  * @driver: Driver model representation of the driver
@@ -214,8 +218,7 @@ void hsi_free_msg(struct hsi_msg *msg);
  * @start_tx: Callback to inform that a client wants to TX data
  * @stop_tx: Callback to inform that a client no longer wishes to TX data
  * @release: Callback to inform that a client no longer uses the port
- * @clients: List of hsi_clients using the port.
- * @clock: Lock to serialize access to the clients list.
+ * @n_head: Notifier chain for signaling port events to the clients.
  */
 struct hsi_port {
         struct device                   device;
@@ -231,14 +234,14 @@ struct hsi_port {
         int                             (*start_tx)(struct hsi_client *cl);
         int                             (*stop_tx)(struct hsi_client *cl);
         int                             (*release)(struct hsi_client *cl);
-        struct list_head                clients;
-        spinlock_t                      clock;
+        /* private */
+        struct atomic_notifier_head     n_head;
 };
 
 #define to_hsi_port(dev) container_of(dev, struct hsi_port, device)
 #define hsi_get_port(cl) to_hsi_port((cl)->device.parent)
 
-void hsi_event(struct hsi_port *port, unsigned int event);
+int hsi_event(struct hsi_port *port, unsigned long event);
 int hsi_claim_port(struct hsi_client *cl, unsigned int share);
 void hsi_release_port(struct hsi_client *cl);