Cc: cphealy@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Andy Shevchenko <redacted>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <redacted>
---

Changes since v2 (see [v2]):

        - Changed subject and commit message wording to better reflect
          nature of the patch

        - Various spelling, formatting, documentation and wording
          fixes as caught/suggested by Andy

Changes since v1 (see [v1]):

        - Make timeout to be a total(as opposed to per-iteration)
          timeout

        - Keep serdev_device_write_buf() as a wrapper arount
          serdev_device_write() for compatibility

[v2] https://lkml.org/lkml/2017/3/28/942
[v1] https://lkml.org/lkml/2017/3/20/650

 drivers/tty/serdev/core.c | 36 +++++++++++++++++++++++++++++++-----
 include/linux/serdev.h    | 17 +++++++++++++++--
 2 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index f4c6c90..6701d10 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 5176cdc..0beaff8 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 */
--

2.9.3