thinkpad-acpi: remove HKEY disable functionality

The HKEY disable functionality basically cripples the entire event
model of the ThinkPad firmware and of the thinkpad-acpi driver.
Remove this functionality from the driver.  HKEY must be enabled at
all times while thinkpad-acpi is loaded, and disabled otherwise.

For sysfs, according to the sysfs ABI and the thinkpad-acpi sysfs
rules of engagement, we will just remove the attributes.  This will be
done in two stages: disable their function now, after two kernel
releases, remove the attributes.

For procfs, we call WARN().  If nothing triggers it, I will simply
remove the enable/disable commands entirely in the future along with
the sysfs attributes.

I don't expect much, if any fallout from this.  There really isn't any
reason to mess with hotkey_enable or with the enable/disable commands
to /proc/acpi/ibm/hotkey, and this has been true for years...

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 19 insertions, 20 deletions

diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index e8f52fbadfe0..de6f14c79070 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -179,17 +179,14 @@ system.  Enabling the hotkey functionality of thinkpad-acpi signals the
 firmware that such a driver is present, and modifies how the ThinkPad
 firmware will behave in many situations.
 
-The driver enables the hot key feature automatically when loaded.  The
-feature can later be disabled and enabled back at runtime.  The driver
-will also restore the hot key feature to its previous state and mask
-when it is unloaded.
+The driver enables the HKEY ("hot key") event reporting automatically
+when loaded, and disables it when it is removed.
 
-When the hotkey feature is enabled and the hot key mask is set (see
-below), the driver will report HKEY events in the following format:
+The driver will report HKEY events in the following format:
 
 	ibm/hotkey HKEY 00000080 0000xxxx
 
-Some of these events refer to hot key presses, but not all.
+Some of these events refer to hot key presses, but not all of them.
 
 The driver will generate events over the input layer for hot keys and
 radio switches, and over the ACPI netlink layer for other events.  The
@@ -221,13 +218,17 @@ procfs notes:
 
 The following commands can be written to the /proc/acpi/ibm/hotkey file:
 
-	echo enable > /proc/acpi/ibm/hotkey -- enable the hot keys feature
-	echo disable > /proc/acpi/ibm/hotkey -- disable the hot keys feature
 	echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
 	echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
 	... any other 8-hex-digit mask ...
 	echo reset > /proc/acpi/ibm/hotkey -- restore the original mask
 
+The following commands have been deprecated and will cause the kernel
+to log a warning:
+
+	echo enable > /proc/acpi/ibm/hotkey -- does nothing
+	echo disable > /proc/acpi/ibm/hotkey -- returns an error
+
 The procfs interface does not support NVRAM polling control.  So as to
 maintain maximum bug-to-bug compatibility, it does not report any masks,
 nor does it allow one to manipulate the hot key mask when the firmware
@@ -236,12 +237,9 @@ does not support masks at all, even if NVRAM polling is in use.
 sysfs notes:
 
 	hotkey_bios_enabled:
-		Returns the status of the hot keys feature when
-		thinkpad-acpi was loaded.  Upon module unload, the hot
-		key feature status will be restored to this value.
+		DEPRECATED, WILL BE REMOVED SOON.
 
-		0: hot keys were disabled
-		1: hot keys were enabled (unusual)
+		Returns 0.
 
 	hotkey_bios_mask:
 		Returns the hot keys mask when thinkpad-acpi was loaded.
@@ -249,13 +247,10 @@ sysfs notes:
 		to this value.
 
 	hotkey_enable:
-		Enables/disables the hot keys feature in the ACPI
-		firmware, and reports current status of the hot keys
-		feature.  Has no effect on the NVRAM hot key polling
-		functionality.
+		DEPRECATED, WILL BE REMOVED SOON.
 
-		0: disables the hot keys feature / feature disabled
-		1: enables the hot keys feature / feature enabled
+		0: returns -EPERM
+		1: does nothing
 
 	hotkey_mask:
 		bit mask to enable driver-handling (and depending on
@@ -1535,3 +1530,7 @@ Sysfs interface changelog:
 
 0x020200:	Add poll()/select() support to the following attributes:
 		hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
+
+0x020300:	hotkey enable/disable support removed, attributes
+		hotkey_bios_enabled and hotkey_enable deprecated and
+		marked for removal.