vsprintf: Add support for IORESOURCE_UNSET in %pR

Sometimes we have a struct resource where we know the type (MEM/IO/etc.)
and the size, but we haven't assigned address space for it.  The
IORESOURCE_UNSET flag is a way to indicate this situation.  For these
"unset" resources, the start address is meaningless, so print only the
size, e.g.,

  - pci 0000:0c:00.0: reg 184: [mem 0x00000000-0x00001fff 64bit]
  + pci 0000:0c:00.0: reg 184: [mem size 0x2000 64bit]

For %pr (printing with raw flags), we still print the address range,
because %pr is mostly used for debugging anyway.

Thanks to Fengguang Wu <fengguang.wu@intel.com> for suggesting
resource_size().
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

include/linux/ioport.h

@@ -51,7 +51,7 @@ struct resource {
 
 #define IORESOURCE_EXCLUSIVE	0x08000000	/* Userland may not map this resource */
 #define IORESOURCE_DISABLED	0x10000000
-#define IORESOURCE_UNSET	0x20000000
+#define IORESOURCE_UNSET	0x20000000	/* No address assigned yet */
 #define IORESOURCE_AUTO		0x40000000
 #define IORESOURCE_BUSY		0x80000000	/* Driver has marked this resource busy */
 

lib/vsprintf.c

@@ -719,10 +719,15 @@ char *resource_string(char *buf, char *end, struct resource *res,
 		specp = &mem_spec;
 		decode = 0;
 	}
-	p = number(p, pend, res->start, *specp);
-	if (res->start != res->end) {
-		*p++ = '-';
-		p = number(p, pend, res->end, *specp);
+	if (decode && res->flags & IORESOURCE_UNSET) {
+		p = string(p, pend, "size ", str_spec);
+		p = number(p, pend, resource_size(res), *specp);
+	} else {
+		p = number(p, pend, res->start, *specp);
+		if (res->start != res->end) {
+			*p++ = '-';
+			p = number(p, pend, res->end, *specp);
+		}
 	}
 	if (decode) {
 		if (res->flags & IORESOURCE_MEM_64)