iommu/vt-d: Use DEVICE_ATTR_RO macro

Use DEVICE_ATTR_RO() helper instead of plain DEVICE_ATTR(),
which makes the code a bit shorter and easier to read.
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210528130229.22108-1-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20210610020115.1637656-19-baolu.lu@linux.intel.comSigned-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.c

@@ -4139,62 +4139,56 @@ static inline struct intel_iommu *dev_to_intel_iommu(struct device *dev)
 	return container_of(iommu_dev, struct intel_iommu, iommu);
 }
 
-static ssize_t intel_iommu_show_version(struct device *dev,
-					struct device_attribute *attr,
-					char *buf)
+static ssize_t version_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
 {
 	struct intel_iommu *iommu = dev_to_intel_iommu(dev);
 	u32 ver = readl(iommu->reg + DMAR_VER_REG);
 	return sprintf(buf, "%d:%d\n",
 		       DMAR_VER_MAJOR(ver), DMAR_VER_MINOR(ver));
 }
-static DEVICE_ATTR(version, S_IRUGO, intel_iommu_show_version, NULL);
+static DEVICE_ATTR_RO(version);
 
-static ssize_t intel_iommu_show_address(struct device *dev,
-					struct device_attribute *attr,
-					char *buf)
+static ssize_t address_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
 {
 	struct intel_iommu *iommu = dev_to_intel_iommu(dev);
 	return sprintf(buf, "%llx\n", iommu->reg_phys);
 }
-static DEVICE_ATTR(address, S_IRUGO, intel_iommu_show_address, NULL);
+static DEVICE_ATTR_RO(address);
 
-static ssize_t intel_iommu_show_cap(struct device *dev,
-				    struct device_attribute *attr,
-				    char *buf)
+static ssize_t cap_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
 {
 	struct intel_iommu *iommu = dev_to_intel_iommu(dev);
 	return sprintf(buf, "%llx\n", iommu->cap);
 }
-static DEVICE_ATTR(cap, S_IRUGO, intel_iommu_show_cap, NULL);
+static DEVICE_ATTR_RO(cap);
 
-static ssize_t intel_iommu_show_ecap(struct device *dev,
-				    struct device_attribute *attr,
-				    char *buf)
+static ssize_t ecap_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
 {
 	struct intel_iommu *iommu = dev_to_intel_iommu(dev);
 	return sprintf(buf, "%llx\n", iommu->ecap);
 }
-static DEVICE_ATTR(ecap, S_IRUGO, intel_iommu_show_ecap, NULL);
+static DEVICE_ATTR_RO(ecap);
 
-static ssize_t intel_iommu_show_ndoms(struct device *dev,
-				      struct device_attribute *attr,
-				      char *buf)
+static ssize_t domains_supported_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
 {
 	struct intel_iommu *iommu = dev_to_intel_iommu(dev);
 	return sprintf(buf, "%ld\n", cap_ndoms(iommu->cap));
 }
-static DEVICE_ATTR(domains_supported, S_IRUGO, intel_iommu_show_ndoms, NULL);
+static DEVICE_ATTR_RO(domains_supported);
 
-static ssize_t intel_iommu_show_ndoms_used(struct device *dev,
-					   struct device_attribute *attr,
-					   char *buf)
+static ssize_t domains_used_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
 {
 	struct intel_iommu *iommu = dev_to_intel_iommu(dev);
 	return sprintf(buf, "%d\n", bitmap_weight(iommu->domain_ids,
 						  cap_ndoms(iommu->cap)));
 }
-static DEVICE_ATTR(domains_used, S_IRUGO, intel_iommu_show_ndoms_used, NULL);
+static DEVICE_ATTR_RO(domains_used);
 
 static struct attribute *intel_iommu_attrs[] = {
 	&dev_attr_version.attr,