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Input: i8042 - allow insmod to succeed on devices without an i8042 controller

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[ Upstream commit b1884583fcd17d6a1b1bba94bbb5826e6b5c6e17 ]

The i8042 module exports several symbols which may be used by other
modules.

Before this commit it would refuse to load (when built as a module itself)
on systems without an i8042 controller.

This is a problem specifically for the asus-nb-wmi module. Many Asus
laptops support the Asus WMI interface. Some of them have an i8042
controller and need to use i8042_install_filter() to filter some kbd
events. Other models do not have an i8042 controller (e.g. they use an
USB attached kbd).

Before this commit the asus-nb-wmi driver could not be loaded on Asus
models without an i8042 controller, when the i8042 code was built as
a module (as Arch Linux does) because the module_init function of the
i8042 module would fail with -ENODEV and thus the i8042_install_filter
symbol could not be loaded.

This commit fixes this by exiting from module_init with a return code
of 0 if no controller is found.  It also adds a i8042_present bool to
make the module_exit function a no-op in this case and also adds a
check for i8042_present to the exported i8042_command function.

The latter i8042_present check should not really be necessary because
when builtin that function can already be used on systems without
an i8042 controller, but better safe then sorry.

Reported-and-tested-by: Marius Iacob <themariusus@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20201008112628.3979-2-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Hans de Goede 2020-10-26 20:53:57 -07:00 committed by Greg Kroah-Hartman
parent dbe67dcf97
commit 8f68a28c9e
1 changed files with 11 additions and 1 deletions
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12
drivers/input/serio/i8042.c
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@ -121,6 +121,7 @@ module_param_named(unmask_kbd_data, i8042_unmask_kbd_data, bool, 0600);
MODULE_PARM_DESC(unmask_kbd_data, "Unconditional enable (may reveal sensitive data) of normally sanitize-filtered kbd data traffic debug log [pre-condition: i8042.debug=1 enabled]");
#endif
static bool i8042_present;
static bool i8042_bypass_aux_irq_test;
static char i8042_kbd_firmware_id[128];
static char i8042_aux_firmware_id[128];
@ -341,6 +342,9 @@ int i8042_command(unsigned char *param, int command)
unsigned long flags;
int retval;
if (!i8042_present)
return -1;
spin_lock_irqsave(&i8042_lock, flags);
retval = __i8042_command(param, command);
spin_unlock_irqrestore(&i8042_lock, flags);
@ -1609,12 +1613,15 @@ static int __init i8042_init(void)
err = i8042_platform_init();
if (err)
return err;
return (err == -ENODEV) ? 0 : err;
err = i8042_controller_check();
if (err)
goto err_platform_exit;
/* Set this before creating the dev to allow i8042_command to work right away */
i8042_present = true;
pdev = platform_create_bundle(&i8042_driver, i8042_probe, NULL, 0, NULL, 0);
if (IS_ERR(pdev)) {
err = PTR_ERR(pdev);
@ -1633,6 +1640,9 @@ static int __init i8042_init(void)
static void __exit i8042_exit(void)
{
if (!i8042_present)
return;
platform_device_unregister(i8042_platform_device);
platform_driver_unregister(&i8042_driver);
i8042_platform_exit();