[PATCH] Input: serio - add writing multiple bytes at once

[David Engraf]

The current version only supports forwarding a single byte to the tty
layer.

This patch adds serio_write_length() to allow a serport driver writing
multiple bytes at once. The patch also includes a fallback to
serio_write_length() when a driver did not register a single byte function.

Signed-off-by: David Engraf <david.eng...@sysgo.com>
---
 drivers/input/serio/serport.c |  7 ++++---
 include/linux/serio.h         | 13 ++++++++++++-
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c
index f8ead9f9c77e..209343f636a3 100644
--- a/drivers/input/serio/serport.c
+++ b/drivers/input/serio/serport.c
@@ -45,10 +45,11 @@ struct serport {
  * Callback functions from the serio code.
  */
 
-static int serport_serio_write(struct serio *serio, unsigned char data)
+static int serport_serio_write_length(struct serio *serio,
+                                     const unsigned char *data, int count)
 {
        struct serport *serport = serio->port_data;
-       return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
+       return -(serport->tty->ops->write(serport->tty, data, count) != count);
 }
 
 static int serport_serio_open(struct serio *serio)
@@ -176,7 +177,7 @@ static ssize_t serport_ldisc_read(struct tty_struct * tty, 
struct file * file, u
        snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty));
        serio->id = serport->id;
        serio->id.type = SERIO_RS232;
-       serio->write = serport_serio_write;
+       serio->write_length = serport_serio_write_length;
        serio->open = serport_serio_open;
        serio->close = serport_serio_close;
        serio->port_data = serport;
diff --git a/include/linux/serio.h b/include/linux/serio.h
index 138a5efe863a..6f5cb92d0f22 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -35,6 +35,8 @@ struct serio {
        spinlock_t lock;
 
        int (*write)(struct serio *, unsigned char);
+       int (*write_length)(struct serio *serio, const unsigned char *data,
+                           int count);
        int (*open)(struct serio *);
        void (*close)(struct serio *);
        int (*start)(struct serio *);
@@ -122,12 +124,21 @@ void serio_unregister_driver(struct serio_driver *drv);
        module_driver(__serio_driver, serio_register_driver, \
                       serio_unregister_driver)
 
+static inline int serio_write_length(struct serio *serio,
+                                    const unsigned char *data, int count)
+{
+       if (serio->write_length)
+               return serio->write_length(serio, data, count);
+       else
+               return -1;
+}
+
 static inline int serio_write(struct serio *serio, unsigned char data)
 {
        if (serio->write)
                return serio->write(serio, data);
        else
-               return -1;
+               return serio_write_length(serio, &data, 1);
 }
 
 static inline void serio_drv_write_wakeup(struct serio *serio)
-- 
2.14.1