lib: Add check of event support for gasops

Not all events are supported by every gen/variant of the Switchtec
firmware. To solve this, since Gen4, a new bit in each event header is
introduced to indicate if an event is supported by the firmware. Add
support of this bit in the gasops for sideband interfaces.

inc/switchtec/registers.h

@@ -39,6 +39,7 @@
 #define SWITCHTEC_EVENT_EN_CLI   BIT(2)
 #define SWITCHTEC_EVENT_EN_IRQ   BIT(3)
 #define SWITCHTEC_EVENT_FATAL    BIT(4)
+#define SWITCHTEC_EVENT_NOT_SUPP BIT(31)
 
 #ifdef MSVC
 #pragma warning(disable: 4201)

lib/platform/gasops.c

@@ -468,6 +468,11 @@ static int event_ctl(struct switchtec_dev *dev, enum switchtec_event_id e,
 	}
 
 	hdr = __gas_read32(dev, reg);
+	if (hdr & SWITCHTEC_EVENT_NOT_SUPP) {
+		errno = ENOTSUP;
+		return -errno;
+	}
+
 	if (data)
 		for (i = 0; i < 5; i++)
 			data[i] = __gas_read32(dev, &reg[i + 1]);
@@ -518,7 +523,7 @@ int gasop_event_ctl(struct switchtec_dev *dev, enum switchtec_event_id e,
 
 		for (index = 0; index < nr_idxs; index++) {
 			ret = event_ctl(dev, e, index, flags, data);
-			if (ret < 0)
+			if (ret < 0 && ret != -ENOTSUP)
 				return ret;
 		}
 	} else {