From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Mon, 19 Jul 2021 21:34:40 +0000 (-0700)
Subject: Input: serio - make write method mandatory
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=81c7c0a350bfe9306ad9fb10356534ede8f4ab31;p=linux.git

Input: serio - make write method mandatory

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.

Link: https://lore.kernel.org/r/YFgUxG/TljMuVeQ3@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---

diff --git a/drivers/input/serio/ams_delta_serio.c b/drivers/input/serio/ams_delta_serio.c
index 1c0be299f1790..a1c3148979511 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 29f491082926a..8d229a11bb6bf 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 6c27d413da921..075f1b8d76faf 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)