drm/xe: Add helper to format SR-IOV function name

While the GuC firmware and the Xe driver are using VF identifier
VFID(0) to represent the Physical Function, we should avoid using
"VF0" name and use proper "PF" name in all user facing messages
related to the Physical Function and use "VFn" name only when
referrinf to the true Virtual Function. Add simple helper to get
properly formatted function name based on the function number.
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240415173937.1287-2-michal.wajdeczko@intel.com

drivers/gpu/drm/xe/xe_sriov.c

@@ -122,3 +122,20 @@ void xe_sriov_print_info(struct xe_device *xe, struct drm_printer *p)
 	drm_printf(p, "enabled: %s\n", str_yes_no(IS_SRIOV(xe)));
 	drm_printf(p, "mode: %s\n", xe_sriov_mode_to_string(xe_device_sriov_mode(xe)));
 }
+
+/**
+ * xe_sriov_function_name() - Get SR-IOV Function name.
+ * @n: the Function number (identifier) to get name of
+ * @buf: the buffer to format to
+ * @size: size of the buffer (shall be at least 5 bytes)
+ *
+ * Return: formatted function name ("PF" or "VF%u").
+ */
+const char *xe_sriov_function_name(unsigned int n, char *buf, size_t size)
+{
+	if (n)
+		snprintf(buf, size, "VF%u", n);
+	else
+		strscpy(buf, "PF", size);
+	return buf;
+}

drivers/gpu/drm/xe/xe_sriov.h

@@ -13,6 +13,7 @@
 struct drm_printer;
 
 const char *xe_sriov_mode_to_string(enum xe_sriov_mode mode);
+const char *xe_sriov_function_name(unsigned int n, char *buf, size_t len);
 
 void xe_sriov_probe_early(struct xe_device *xe);
 void xe_sriov_print_info(struct xe_device *xe, struct drm_printer *p);