2 files changed, 46 insertions, 7 deletions

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index f4c6c90add78..6701d1011fce 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -116,17 +116,41 @@ void serdev_device_close(struct serdev_device *serdev)
 }
 EXPORT_SYMBOL_GPL(serdev_device_close);
 
-int serdev_device_write_buf(struct serdev_device *serdev,
-                            const unsigned char *buf, size_t count)
+void serdev_device_write_wakeup(struct serdev_device *serdev)
+{
+        complete(&serdev->write_comp);
+}
+EXPORT_SYMBOL_GPL(serdev_device_write_wakeup);
+
+int serdev_device_write(struct serdev_device *serdev,
+                        const unsigned char *buf, size_t count,
+                        unsigned long timeout)
 {
         struct serdev_controller *ctrl = serdev->ctrl;
+        int ret;
 
-        if (!ctrl || !ctrl->ops->write_buf)
+        if (!ctrl || !ctrl->ops->write_buf ||
+            (timeout && !serdev->ops->write_wakeup))
                 return -EINVAL;
 
-        return ctrl->ops->write_buf(ctrl, buf, count);
+        mutex_lock(&serdev->write_lock);
+        do {
+                reinit_completion(&serdev->write_comp);
+
+                ret = ctrl->ops->write_buf(ctrl, buf, count);
+                if (ret < 0)
+                        break;
+
+                buf += ret;
+                count -= ret;
+
+        } while (count &&
+                 (timeout = wait_for_completion_timeout(&serdev->write_comp,
+                                                        timeout)));
+        mutex_unlock(&serdev->write_lock);
+        return ret < 0 ? ret : (count ? -ETIMEDOUT : 0);
 }
-EXPORT_SYMBOL_GPL(serdev_device_write_buf);
+EXPORT_SYMBOL_GPL(serdev_device_write);
 
 void serdev_device_write_flush(struct serdev_device *serdev)
 {
@@ -232,6 +256,8 @@ struct serdev_device *serdev_device_alloc(struct serdev_controller *ctrl)
         serdev->dev.parent = &ctrl->dev;
         serdev->dev.bus = &serdev_bus_type;
         serdev->dev.type = &serdev_device_type;
+        init_completion(&serdev->write_comp);
+        mutex_init(&serdev->write_lock);
         return serdev;
 }
 EXPORT_SYMBOL_GPL(serdev_device_alloc);
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index 5176cdc2057f..0beaff886992 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -39,12 +39,16 @@ struct serdev_device_ops {
  * @nr:         Device number on serdev bus.
  * @ctrl:       serdev controller managing this device.
  * @ops:        Device operations.
+ * @write_comp  Completion used by serdev_device_write() internally
+ * @write_lock  Lock to serialize access when writing data
  */
 struct serdev_device {
         struct device dev;
         int nr;
         struct serdev_controller *ctrl;
         const struct serdev_device_ops *ops;
+        struct completion write_comp;
+        struct mutex write_lock;
 };
 
 static inline struct serdev_device *to_serdev_device(struct device *d)
@@ -186,7 +190,8 @@ int serdev_device_open(struct serdev_device *);
 void serdev_device_close(struct serdev_device *);
 unsigned int serdev_device_set_baudrate(struct serdev_device *, unsigned int);
 void serdev_device_set_flow_control(struct serdev_device *, bool);
-int serdev_device_write_buf(struct serdev_device *, const unsigned char *, size_t);
+void serdev_device_write_wakeup(struct serdev_device *);
+int serdev_device_write(struct serdev_device *, const unsigned char *, size_t, unsigned long);
 void serdev_device_write_flush(struct serdev_device *);
 int serdev_device_write_room(struct serdev_device *);
 
@@ -223,7 +228,8 @@ static inline unsigned int serdev_device_set_baudrate(struct serdev_device *sdev
         return 0;
 }
 static inline void serdev_device_set_flow_control(struct serdev_device *sdev, bool enable) {}
-static inline int serdev_device_write_buf(struct serdev_device *sdev, const unsigned char *buf, size_t count)
+static inline int serdev_device_write(struct serdev_device *sdev, const unsigned char *buf,
+                                      size_t count, unsigned long timeout)
 {
         return -ENODEV;
 }
@@ -259,4 +265,11 @@ static inline struct device *serdev_tty_port_register(struct tty_port *port,
 static inline void serdev_tty_port_unregister(struct tty_port *port) {}
 #endif /* CONFIG_SERIAL_DEV_CTRL_TTYPORT */
 
+static inline int serdev_device_write_buf(struct serdev_device *serdev,
+                                          const unsigned char *data,
+                                          size_t count)
+{
+        return serdev_device_write(serdev, data, count, 0);
+}
+
 #endif /*_LINUX_SERDEV_H */