[PATCHv5] hp-wmi: limit hotkey enable

[Kyle Evans <kvans32@gmail.com>]

Do not write initialize magic on systems that do not have
feature query 0xb. Fixes Bug #82451.

Redefine FEATURE_QUERY to align with 0xb and FEATURE2 with 0xd
for code clearity.

Add a new test function, hp_wmi_bios_2008_later() & simplify
hp_wmi_bios_2009_later(), which fixes a bug in cases where
an improper value is returned. Probably also fixes Bug #69131.

Add missing __init tag.

Signed-off-by: Kyle Evans <kvans32@gmail.com>
---
 Since v1:
 - Refactored feature query 0xb into separate function
 - Redefine FEATURE_QUERY to align with 0xb and FEATURE2 with 0xd

 Since v2:
 - Simplify hp_wmi_bios_200x_later functions. No longer returns true 
 (4) when the test fails. However, if state is somehow useful, that is lost.

 Since v3:
 - Fix whitespace, email client reformatting.

 Since v4:
 - Fix "bios" typo.
 - Add __init tag.

 drivers/platform/x86/hp-wmi.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/platform/x86/hp-wmi.c b/drivers/platform/x86/hp-wmi.c
index 0669731..fb4dd7b 100644
--- a/drivers/platform/x86/hp-wmi.c
+++ b/drivers/platform/x86/hp-wmi.c
@@ -54,8 +54,9 @@ MODULE_ALIAS("wmi:5FB7F034-2C63-45e9-BE91-3D44E2C707E4");
 #define HPWMI_HARDWARE_QUERY 0x4
 #define HPWMI_WIRELESS_QUERY 0x5
 #define HPWMI_BIOS_QUERY 0x9
+#define HPWMI_FEATURE_QUERY 0xb
 #define HPWMI_HOTKEY_QUERY 0xc
-#define HPWMI_FEATURE_QUERY 0xd
+#define HPWMI_FEATURE2_QUERY 0xd
 #define HPWMI_WIRELESS2_QUERY 0x1b
 #define HPWMI_POSTCODEERROR_QUERY 0x2a
 
@@ -295,25 +296,33 @@ static int hp_wmi_tablet_state(void)
 	return (state & 0x4) ? 1 : 0;
 }
 
-static int __init hp_wmi_bios_2009_later(void)
+static int __init hp_wmi_bios_2008_later(void)
 {
 	int state = 0;
 	int ret = hp_wmi_perform_query(HPWMI_FEATURE_QUERY, 0, &state,
 				       sizeof(state), sizeof(state));
-	if (ret)
-		return ret;
+	if (!ret)
+		return 1;
 
-	return (state & 0x10) ? 1 : 0;
+	return (ret == HPWMI_RET_UNKNOWN_CMDTYPE) ? 0 : -ENXIO;
 }
 
-static int hp_wmi_enable_hotkeys(void)
+static int __init hp_wmi_bios_2009_later(void)
 {
-	int ret;
-	int query = 0x6e;
+	int state = 0;
+	int ret = hp_wmi_perform_query(HPWMI_FEATURE2_QUERY, 0, &state,
+				       sizeof(state), sizeof(state));
+	if (!ret)
+		return 1;
 
-	ret = hp_wmi_perform_query(HPWMI_BIOS_QUERY, 1, &query, sizeof(query),
-				   0);
+	return (ret == HPWMI_RET_UNKNOWN_CMDTYPE) ? 0 : -ENXIO;
+}
 
+static int __init hp_wmi_enable_hotkeys(void)
+{
+	int value = 0x6e;
+	int ret = hp_wmi_perform_query(HPWMI_BIOS_QUERY, 1, &value,
+				       sizeof(value), 0);
 	if (ret)
 		return -EINVAL;
 	return 0;
@@ -663,7 +672,7 @@ static int __init hp_wmi_input_setup(void)
 			    hp_wmi_tablet_state());
 	input_sync(hp_wmi_input_dev);
 
-	if (hp_wmi_bios_2009_later() == 4)
+	if (!hp_wmi_bios_2009_later() && hp_wmi_bios_2008_later())
 		hp_wmi_enable_hotkeys();
 
 	status = wmi_install_notify_handler(HPWMI_EVENT_GUID, hp_wmi_notify, NULL);
-- 
1.8.5.5