Input: i8042 - Add support for platform filter contexts

Currently the platform filter cannot access any driver-specific state
which forces drivers installing a i8042 filter to have at least some
kind of global pointer for their filter.

Allow callers of i8042_install_filter() to submit a context pointer
which is then passed to the i8042 filter. This frees drivers from the
responsibility of having to manage this global pointer themself.

Also introduce a separate type for the i8042 filter (i8042_filter_t)
so that the function definitions can stay compact.

Tested on a Dell Inspiron 3505.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20250113221314.435812-1-W_Armin@gmx.de
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

2 files changed, 12 insertions, 9 deletions

diff --git a/drivers/input/misc/ideapad_slidebar.c b/drivers/input/misc/ideapad_slidebar.c
index f6e5fc807b4d..ab2e0a401904 100644
--- a/drivers/input/misc/ideapad_slidebar.c
+++ b/drivers/input/misc/ideapad_slidebar.c
@@ -121,7 +121,7 @@ static void slidebar_mode_set(u8 mode)
 }
 
 static bool slidebar_i8042_filter(unsigned char data, unsigned char str,
-				  struct serio *port)
+				  struct serio *port, void *context)
 {
 	static bool extended = false;
 
@@ -219,7 +219,7 @@ static int __init ideapad_probe(struct platform_device* pdev)
 	input_set_capability(slidebar_input_dev, EV_ABS, ABS_X);
 	input_set_abs_params(slidebar_input_dev, ABS_X, 0, 0xff, 0, 0);
 
-	err = i8042_install_filter(slidebar_i8042_filter);
+	err = i8042_install_filter(slidebar_i8042_filter, NULL);
 	if (err) {
 		dev_err(&pdev->dev,
 			"Failed to install i8042 filter: %d\n", err);
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 509330a27880..cab5a4c5baf5 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -179,8 +179,8 @@ static struct platform_device *i8042_platform_device;
 static struct notifier_block i8042_kbd_bind_notifier_block;
 
 static bool i8042_handle_data(int irq);
-static bool (*i8042_platform_filter)(unsigned char data, unsigned char str,
-				     struct serio *serio);
+static i8042_filter_t i8042_platform_filter;
+static void *i8042_platform_filter_context;
 
 void i8042_lock_chip(void)
 {
@@ -194,8 +194,7 @@ void i8042_unlock_chip(void)
 }
 EXPORT_SYMBOL(i8042_unlock_chip);
 
-int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
-					struct serio *serio))
+int i8042_install_filter(i8042_filter_t filter, void *context)
 {
 	guard(spinlock_irqsave)(&i8042_lock);
 
@@ -203,12 +202,12 @@ int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
 		return -EBUSY;
 
 	i8042_platform_filter = filter;
+	i8042_platform_filter_context = context;
 	return 0;
 }
 EXPORT_SYMBOL(i8042_install_filter);
 
-int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,
-				       struct serio *port))
+int i8042_remove_filter(i8042_filter_t filter)
 {
 	guard(spinlock_irqsave)(&i8042_lock);
 
@@ -216,6 +215,7 @@ int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,
 		return -EINVAL;
 
 	i8042_platform_filter = NULL;
+	i8042_platform_filter_context = NULL;
 	return 0;
 }
 EXPORT_SYMBOL(i8042_remove_filter);
@@ -480,7 +480,10 @@ static bool i8042_filter(unsigned char data, unsigned char str,
 		}
 	}
 
-	if (i8042_platform_filter && i8042_platform_filter(data, str, serio)) {
+	if (!i8042_platform_filter)
+		return false;
+
+	if (i8042_platform_filter(data, str, serio, i8042_platform_filter_context)) {
 		dbg("Filtered out by platform filter\n");
 		return true;
 	}