[PATCH] Input: serio - make write method mandatory

[Dmitry Torokhov]

Given that all serio drivers except one implement write() method
let's make it mandatory to avoid testing for its presence whenever
we attempt to use it.

Signed-off-by: Dmitry Torokhov <dmitry.torok...@gmail.com>
---
 drivers/input/serio/ams_delta_serio.c | 6 ++++++
 drivers/input/serio/serio.c           | 5 +++++
 include/linux/serio.h                 | 5 +----
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/input/serio/ams_delta_serio.c 
b/drivers/input/serio/ams_delta_serio.c
index 1c0be299f179..a1c314897951 100644
--- a/drivers/input/serio/ams_delta_serio.c
+++ b/drivers/input/serio/ams_delta_serio.c
@@ -89,6 +89,11 @@ static irqreturn_t ams_delta_serio_interrupt(int irq, void 
*dev_id)
        return IRQ_HANDLED;
 }
 
+static int ams_delta_serio_write(struct serio *serio, u8 data)
+{
+       return -EINVAL;
+}
+
 static int ams_delta_serio_open(struct serio *serio)
 {
        struct ams_delta_serio *priv = serio->port_data;
@@ -157,6 +162,7 @@ static int ams_delta_serio_init(struct platform_device 
*pdev)
        priv->serio = serio;
 
        serio->id.type = SERIO_8042;
+       serio->write = ams_delta_serio_write;
        serio->open = ams_delta_serio_open;
        serio->close = ams_delta_serio_close;
        strlcpy(serio->name, "AMS DELTA keyboard adapter", sizeof(serio->name));
diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index 29f491082926..8d229a11bb6b 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -694,6 +694,11 @@ EXPORT_SYMBOL(serio_reconnect);
  */
 void __serio_register_port(struct serio *serio, struct module *owner)
 {
+       if (!serio->write) {
+               pr_err("%s: refusing to register %s without write method\n",
+                      __func__, serio->name);
+               return;
+       }
        serio_init_port(serio);
        serio_queue_event(serio, owner, SERIO_REGISTER_PORT);
 }
diff --git a/include/linux/serio.h b/include/linux/serio.h
index 6c27d413da92..075f1b8d76fa 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -121,10 +121,7 @@ void serio_unregister_driver(struct serio_driver *drv);
 
 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(serio, data);
 }
 
 static inline void serio_drv_write_wakeup(struct serio *serio)
-- 
2.31.0.rc2.261.g7f71774620-goog


-- 
Dmitry