[PATCH 02/17] staging: nuc-wmi: detect WMI API detection

[Mauro Carvalho Chehab]

There are currently 3 known API releases:
            - https://www.intel.com/content/www/us/en/support/articles/000023426/intel-nuc/intel-nuc-kits.html
            - https://raw.githubusercontent.com/nomego/intel_nuc_led/master/specs/INTEL_WMI_LED_0.64.pdf
            - https://www.intel.com/content/dam/support/us/en/documents/intel-nuc/WMI-Spec-Intel-NUC-NUC10ixFNx.pdf

Add a logic to detect between them, preventing the driver
to work with an unsupported version.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
---
 drivers/staging/nuc-led/nuc-wmi.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/nuc-led/nuc-wmi.c b/drivers/staging/nuc-led/nuc-wmi.c
index 15d956ad8556..b75ddd47e443 100644
--- a/drivers/staging/nuc-led/nuc-wmi.c
+++ b/drivers/staging/nuc-led/nuc-wmi.c
@@ -26,6 +26,13 @@
 #define NUM_INPUT_ARGS		4
 #define NUM_OUTPUT_ARGS		3
 
+enum led_api_rev {
+	LED_API_UNKNOWN,
+	LED_API_NUC6,
+	LED_API_REV_0_64,
+	LED_API_REV_1_0,
+};
+
 enum led_cmds {
 	LED_QUERY			= 0x03,
 	LED_NEW_GET_STATUS		= 0x04,
@@ -33,6 +40,7 @@ enum led_cmds {
 	LED_SET_VALUE			= 0x06,
 	LED_NOTIFICATION		= 0x07,
 	LED_SWITCH_TYPE			= 0x08,
+	LED_VERSION_CONTROL             = 0x09,
 };
 
 enum led_query_subcmd {
@@ -195,7 +203,7 @@ static int nuc_wmi_query_leds(struct device *dev)
 	struct nuc_wmi *priv = dev_get_drvdata(dev);
 	u8 cmd, input[NUM_INPUT_ARGS] = { 0 };
 	u8 output[NUM_OUTPUT_ARGS];
-	int i, id, ret;
+	int i, id, ret, ver = LED_API_UNKNOWN;
 	u8 leds;
 
 	/*
@@ -209,12 +217,28 @@ static int nuc_wmi_query_leds(struct device *dev)
 	cmd = LED_QUERY;
 	input[0] = LED_QUERY_LIST_ALL;
 	ret = nuc_nmi_cmd(dev, cmd, input, output);
-	if (ret) {
+	if (ret == -ENOENT) {
+		ver = LED_API_NUC6;
+	} else if (ret) {
 		dev_warn(dev, "error %d while listing all LEDs\n", ret);
 		return ret;
+	} else {
+		leds = output[0];
 	}
 
-	leds = output[0];
+	if (ver != LED_API_NUC6) {
+		ret = nuc_nmi_cmd(dev, LED_VERSION_CONTROL, input, output);
+		ver = output[0] | output[1] << 16;
+		if (!ver)
+			ver = LED_API_REV_0_64;
+		else if (ver == 0x0126)
+			ver = LED_API_REV_1_0;
+	}
+
+	/* Currently, only API Revision 0.64 is supported */
+	if (ver != LED_API_REV_0_64)
+		return -ENODEV;
+
 	if (!leds) {
 		dev_warn(dev, "No LEDs found\n");
 		return -ENODEV;
-- 
2.31.1