platform/x86: wmi: add WMI support to MODULE_DEVICE_TABLE()

The kernel provides the macro MODULE_DEVICE_TABLE() where driver authors
can specify their device type and their array of device_ids and thereby
trigger the generation of the appropriate MODULE_ALIAS() output. This is
opposed to having to specify one MODULE_ALIAS() for each device. The WMI
device type is currently not supported.

While using MODULE_DEVICE_TABLE() does increase the complexity as well
as spreading out the implementation across the kernel, it does come with
some benefits too;
* It makes different drivers look more similar; if you can specify the
  array of device_ids any device type specific input to MODULE_ALIAS()
  will automatically be generated for you.
* It helps each driver avoid keeping multiple versions of the same
  information in sync. That is, both the array of device_ids and the
  potential multitude of MODULE_ALIAS()'s.

Add WMI support to MODULE_DEVICE_TABLE() by adding info about struct
wmi_device_id in devicetable-offsets.c and add a WMI entry point in
file2alias.c.

The type argument for MODULE_DEVICE_TABLE(type, name) is wmi.
Suggested-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Mattias Jacobsson <2pi@mok.nu>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

scripts/mod/devicetable-offsets.c

@@ -225,5 +225,8 @@ int main(void)
 	DEVID_FIELD(typec_device_id, svid);
 	DEVID_FIELD(typec_device_id, mode);
 
+	DEVID(wmi_device_id);
+	DEVID_FIELD(wmi_device_id, guid_string);
+
 	return 0;
 }

scripts/mod/file2alias.c

@@ -1291,6 +1291,27 @@ static int do_typec_entry(const char *filename, void *symval, char *alias)
 	return 1;
 }
 
+/* Looks like: wmi:guid */
+static int do_wmi_entry(const char *filename, void *symval, char *alias)
+{
+	int len;
+	DEF_FIELD_ADDR(symval, wmi_device_id, guid_string);
+
+	if (strlen(*guid_string) != UUID_STRING_LEN) {
+		warn("Invalid WMI device id 'wmi:%s' in '%s'\n",
+				*guid_string, filename);
+		return 0;
+	}
+
+	len = snprintf(alias, ALIAS_SIZE, WMI_MODULE_PREFIX "%s", *guid_string);
+	if (len < 0 || len >= ALIAS_SIZE) {
+		warn("Could not generate all MODULE_ALIAS's in '%s'\n",
+				filename);
+		return 0;
+	}
+	return 1;
+}
+
 /* Does namelen bytes of name exactly match the symbol? */
 static bool sym_is(const char *name, unsigned namelen, const char *symbol)
 {
@@ -1361,6 +1382,7 @@ static const struct devtable devtable[] = {
 	{"fslmc", SIZE_fsl_mc_device_id, do_fsl_mc_entry},
 	{"tbsvc", SIZE_tb_service_id, do_tbsvc_entry},
 	{"typec", SIZE_typec_device_id, do_typec_entry},
+	{"wmi", SIZE_wmi_device_id, do_wmi_entry},
 };
 
 /* Create MODULE_ALIAS() statements.