coresight: etm4x: Fix missing trctraceidr file in sysfs

The trace ID patchset adjusted the handling of the TRCTRACEIDR register
sysfs to allocate on read.

Although this was initally correct, the final version of the patch series
introduced an error which resulted in the mgmt/trctraceidr file in sysfs
not being visible.

This patch fixes that issue.

Fixes: df487120 ("coresight: etm4x: Update ETM4 driver to use Trace ID API")
Reported-by: Junhao He <hejunhao3@huawei.com>
Link: https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/KK3CVVMRHJWVUORKMFJRSXYCEDFKENQJ/Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230512133054.235073-1-mike.leach@linaro.org

drivers/hwtracing/coresight/coresight-etm4x-sysfs.c

@@ -2411,7 +2411,6 @@ static ssize_t trctraceid_show(struct device *dev,
 
 	return sysfs_emit(buf, "0x%x\n", trace_id);
 }
-static DEVICE_ATTR_RO(trctraceid);
 
 struct etmv4_reg {
 	struct coresight_device *csdev;
@@ -2528,13 +2527,23 @@ coresight_etm4x_attr_reg_implemented(struct kobject *kobj,
 	return 0;
 }
 
-#define coresight_etm4x_reg(name, offset)				\
-	&((struct dev_ext_attribute[]) {				\
-	   {								\
-		__ATTR(name, 0444, coresight_etm4x_reg_show, NULL),	\
-		(void *)(unsigned long)offset				\
-	   }								\
-	})[0].attr.attr
+/*
+ * Macro to set an RO ext attribute with offset and show function.
+ * Offset is used in mgmt group to ensure only correct registers for
+ * the ETM / ETE variant are visible.
+ */
+#define coresight_etm4x_reg_showfn(name, offset, showfn) (	\
+	&((struct dev_ext_attribute[]) {			\
+	   {							\
+		__ATTR(name, 0444, showfn, NULL),		\
+		(void *)(unsigned long)offset			\
+	   }							\
+	})[0].attr.attr						\
+	)
+
+/* macro using the default coresight_etm4x_reg_show function */
+#define coresight_etm4x_reg(name, offset)	\
+	coresight_etm4x_reg_showfn(name, offset, coresight_etm4x_reg_show)
 
 static struct attribute *coresight_etmv4_mgmt_attrs[] = {
 	coresight_etm4x_reg(trcpdcr, TRCPDCR),
@@ -2549,7 +2558,7 @@ static struct attribute *coresight_etmv4_mgmt_attrs[] = {
 	coresight_etm4x_reg(trcpidr3, TRCPIDR3),
 	coresight_etm4x_reg(trcoslsr, TRCOSLSR),
 	coresight_etm4x_reg(trcconfig, TRCCONFIGR),
-	&dev_attr_trctraceid.attr,
+	coresight_etm4x_reg_showfn(trctraceid, TRCTRACEIDR, trctraceid_show),
 	coresight_etm4x_reg(trcdevarch, TRCDEVARCH),
 	NULL,
 };