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Subject[PATCH] serdev: Replace serdev_device_write_buf with serdev_device_write
Date
Convert serdev_device_write_buf's code to be able to transfer amount of
data potentially exceeding "write room" at the moment of invocation.

To support that, also add serdev_device_write_wakeup.

Drivers wanting to use full extent of serdev_device_write functionality
asre expected to provide serdev_device_write_wakeup as a sole handler of
.write_wakeup event or call it as a part of driver's custom
.write_wakeup code.

Drivers wanting to retain old serdev_device_write_buf behaviour can
replace those call to calls to serdev_device_write with timeout of
0. Providing .write_wakeup handler in such case is optional.

Cc: cphealy@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
drivers/tty/serdev/core.c | 36 +++++++++++++++++++++++++++++++-----
include/linux/serdev.h | 11 +++++++++--
2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index f4c6c90..9962d84 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 &&
+ 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..18cbbed 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -39,12 +39,17 @@ 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 Mutext used to esure exclusive access to the bus when
+ * writing data with serdev_device_write()
*/
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)
@@ -186,10 +191,12 @@ 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 *);

+
/*
* serdev device driver functions
*/
@@ -223,7 +230,7 @@ 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)
{
return -ENODEV;
}
--
2.9.3
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