[PATCH v16 1/9] platform/x86: asus-wmi: export symbols used for read/write WMI

[Denis Benato <denis.benato@linux.dev>]

From: "Luke D. Jones" <luke@ljones.dev>

Export symbols for reading/writing WMI symbols using a namespace.
Existing functions:
- asus_wmi_evaluate_method
- asus_wmi_set_devstate
New function:
- asus_wmi_get_devstate_dsts

The new function is intended for use with DSTS WMI method only and
avoids requiring the asus_wmi driver data to select the WMI method.

Co-developed-by: Denis Benato <denis.benato@linux.dev>
Signed-off-by: Denis Benato <denis.benato@linux.dev>
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/platform/x86/asus-wmi.c            | 46 ++++++++++++++++++++--
 include/linux/platform_data/x86/asus-wmi.h |  5 +++
 2 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index e72a2b5d158e..c3e90517ce0f 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -390,7 +390,7 @@ int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval)
 {
 	return asus_wmi_evaluate_method3(method_id, arg0, arg1, 0, retval);
 }
-EXPORT_SYMBOL_GPL(asus_wmi_evaluate_method);
+EXPORT_SYMBOL_NS_GPL(asus_wmi_evaluate_method, "ASUS_WMI");
 
 static int asus_wmi_evaluate_method5(u32 method_id,
 		u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4, u32 *retval)
@@ -554,12 +554,52 @@ static int asus_wmi_get_devstate(struct asus_wmi *asus, u32 dev_id, u32 *retval)
 	return 0;
 }
 
-int asus_wmi_set_devstate(u32 dev_id, u32 ctrl_param,
-				 u32 *retval)
+/**
+ * asus_wmi_get_devstate_dsts() - Get the WMI function state.
+ * @dev_id: The WMI method ID to call.
+ * @retval: A pointer to where to store the value returned from WMI.
+ *
+ * Returns:
+ * * %-ENODEV	- method ID is unsupported.
+ * * %0			- successful and retval is filled.
+ * * %other		- error from WMI call.
+ */
+int asus_wmi_get_devstate_dsts(u32 dev_id, u32 *retval)
+{
+	int err;
+
+	err = asus_wmi_evaluate_method(ASUS_WMI_METHODID_DSTS, dev_id, 0, retval);
+	if (err)
+		return err;
+
+	if ((*retval & ASUS_WMI_DSTS_PRESENCE_BIT) == 0x00)
+		return -ENODEV;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(asus_wmi_get_devstate_dsts, "ASUS_WMI");
+
+/**
+ * asus_wmi_set_devstate() - Set the WMI function state.
+ *
+ * Note: an asus_wmi_set_devstate() call must be paired with a
+ * asus_wmi_get_devstate_dsts() to check if the WMI function is supported.
+ *
+ * @dev_id: The WMI function to call.
+ * @ctrl_param: The argument to be used for this WMI function.
+ * @retval: A pointer to where to store the value returned from WMI.
+ *
+ * Returns:
+ * * %-ENODEV	- method ID is unsupported.
+ * * %0			- successful and retval is filled.
+ * * %other		- error from WMI call.
+ */
+int asus_wmi_set_devstate(u32 dev_id, u32 ctrl_param, u32 *retval)
 {
 	return asus_wmi_evaluate_method(ASUS_WMI_METHODID_DEVS, dev_id,
 					ctrl_param, retval);
 }
+EXPORT_SYMBOL_NS_GPL(asus_wmi_set_devstate, "ASUS_WMI");
 
 /* Helper for special devices with magic return codes */
 static int asus_wmi_get_devstate_bits(struct asus_wmi *asus,
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index 8a515179113d..dbd44d9fbb6f 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -166,6 +166,7 @@ enum asus_ally_mcu_hack {
 #if IS_REACHABLE(CONFIG_ASUS_WMI)
 void set_ally_mcu_hack(enum asus_ally_mcu_hack status);
 void set_ally_mcu_powersave(bool enabled);
+int asus_wmi_get_devstate_dsts(u32 dev_id, u32 *retval);
 int asus_wmi_set_devstate(u32 dev_id, u32 ctrl_param, u32 *retval);
 int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval);
 #else
@@ -179,6 +180,10 @@ static inline int asus_wmi_set_devstate(u32 dev_id, u32 ctrl_param, u32 *retval)
 {
 	return -ENODEV;
 }
+static inline int asus_wmi_get_devstate_dsts(u32 dev_id, u32 *retval)
+{
+	return -ENODEV;
+}
 static inline int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1,
 					   u32 *retval)
 {
-- 
2.51.2