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>

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
+The driver enables the HKEY ("hot key") event reporting automatically
-feature can later be disabled and enabled back at runtime.  The driver
+when loaded, and disables it when it is removed.
-will also restore the hot key feature to its previous state and mask
-when it is unloaded.
 
-When the hotkey feature is enabled and the hot key mask is set (see
+The driver will report HKEY events in the following format:
-below), 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
+		DEPRECATED, WILL BE REMOVED SOON.
-		thinkpad-acpi was loaded.  Upon module unload, the hot
-		key feature status will be restored to this value.
 
-		0: hot keys were disabled
+		Returns 0.
-		1: hot keys were enabled (unusual)
 
 	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
+		DEPRECATED, WILL BE REMOVED SOON.
-		firmware, and reports current status of the hot keys
-		feature.  Has no effect on the NVRAM hot key polling
-		functionality.
 
-		0: disables the hot keys feature / feature disabled
+		0: returns -EPERM
-		1: enables the hot keys feature / feature enabled
+		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.

drivers/platform/x86/thinkpad_acpi.c

@@ -22,7 +22,7 @@
  */
 
 #define TPACPI_VERSION "0.22"
-#define TPACPI_SYSFS_VERSION 0x020200
+#define TPACPI_SYSFS_VERSION 0x020300
 
 /*
  *  Changelog:
@@ -1424,7 +1424,6 @@ static enum {	/* Reasons for waking up */
 
 static int hotkey_autosleep_ack;
 
-static int hotkey_orig_status;
 static u32 hotkey_orig_mask;
 static u32 hotkey_all_mask;
 static u32 hotkey_reserved_mask;
@@ -1571,9 +1570,9 @@ static int hotkey_status_get(int *status)
 	return 0;
 }
 
-static int hotkey_status_set(int status)
+static int hotkey_status_set(bool enable)
 {
-	if (!acpi_evalf(hkey_handle, NULL, "MHKC", "vd", status))
+	if (!acpi_evalf(hkey_handle, NULL, "MHKC", "vd", enable ? 1 : 0))
 		return -EIO;
 
 	return 0;
@@ -1889,6 +1888,9 @@ static ssize_t hotkey_enable_show(struct device *dev,
 {
 	int res, status;
 
+	printk_deprecated_attribute("hotkey_enable",
+			"Hotkey reporting is always enabled");
+
 	res = hotkey_status_get(&status);
 	if (res)
 		return res;
@@ -1901,14 +1903,17 @@ static ssize_t hotkey_enable_store(struct device *dev,
 			    const char *buf, size_t count)
 {
 	unsigned long t;
-	int res;
+
+	printk_deprecated_attribute("hotkey_enable",
+			"Hotkeys can be disabled through hotkey_mask");
 
 	if (parse_strtoul(buf, 1, &t))
 		return -EINVAL;
 
-	res = hotkey_status_set(t);
+	if (t == 0)
+		return -EPERM;
 
-	return (res) ? res : count;
+	return count;
 }
 
 static struct device_attribute dev_attr_hotkey_enable =
@@ -1964,7 +1969,7 @@ static ssize_t hotkey_bios_enabled_show(struct device *dev,
 			   struct device_attribute *attr,
 			   char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%d\n", hotkey_orig_status);
+	return sprintf(buf, "0\n");
 }
 
 static struct device_attribute dev_attr_hotkey_bios_enabled =
@@ -2243,7 +2248,7 @@ static void hotkey_exit(void)
 			   "restoring original hot key mask\n");
 		/* no short-circuit boolean operator below! */
 		if ((hotkey_mask_set(hotkey_orig_mask) |
-		     hotkey_status_set(hotkey_orig_status)) != 0)
+		     hotkey_status_set(false)) != 0)
 			printk(TPACPI_ERR
 			       "failed to restore hot key mask "
 			       "to BIOS defaults\n");
@@ -2438,10 +2443,6 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
 
 	/* hotkey_source_mask *must* be zero for
 	 * the first hotkey_mask_get */
-	res = hotkey_status_get(&hotkey_orig_status);
-	if (res)
-		goto err_exit;
-
 	if (tp_features.hotkey_mask) {
 		res = hotkey_mask_get();
 		if (res)
@@ -2581,7 +2582,7 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
 	}
 
 	dbg_printk(TPACPI_DBG_INIT, "enabling hot key handling\n");
-	res = hotkey_status_set(1);
+	res = hotkey_status_set(true);
 	if (res) {
 		hotkey_exit();
 		return res;
@@ -2926,9 +2927,17 @@ static int hotkey_read(char *p)
 	return len;
 }
 
+static void hotkey_enabledisable_warn(void)
+{
+	tpacpi_log_usertask("procfs hotkey enable/disable");
+	WARN(1, TPACPI_WARN
+	     "hotkey enable/disable functionality has been "
+	     "removed from the driver. Hotkeys are always enabled.\n");
+}
+
 static int hotkey_write(char *buf)
 {
-	int res, status;
+	int res;
 	u32 mask;
 	char *cmd;
 
@@ -2938,17 +2947,16 @@ static int hotkey_write(char *buf)
 	if (mutex_lock_killable(&hotkey_mutex))
 		return -ERESTARTSYS;
 
-	status = -1;
 	mask = hotkey_mask;
 
 	res = 0;
 	while ((cmd = next_cmd(&buf))) {
 		if (strlencmp(cmd, "enable") == 0) {
-			status = 1;
+			hotkey_enabledisable_warn();
 		} else if (strlencmp(cmd, "disable") == 0) {
-			status = 0;
+			hotkey_enabledisable_warn();
+			res = -EPERM;
 		} else if (strlencmp(cmd, "reset") == 0) {
-			status = hotkey_orig_status;
 			mask = hotkey_orig_mask;
 		} else if (sscanf(cmd, "0x%x", &mask) == 1) {
 			/* mask set */
@@ -2959,9 +2967,6 @@ static int hotkey_write(char *buf)
 			goto errexit;
 		}
 	}
-	if (status != -1)
-		res = hotkey_status_set(status);
-
 	if (!res && mask != hotkey_mask)
 		res = hotkey_mask_set(mask);