[PATCH v2] lib: vsprintf: Add %pa format specifier for phys_addr_t types

[Stepan Moskovchenko <stepanm@codeaurora.org>]

Add the %pa format specifier for printing a phys_addr_t
type and its derivative types (such as resource_size_t),
since the physical address size on some platforms can vary
based on build options, regardless of the native integer
type.

Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
---
v2: - Update field width to make room for the '0x' prefix
    - Update documentation to include derivative types

 Documentation/printk-formats.txt |   14 +++++++++++---
 lib/vsprintf.c                   |    7 +++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 8ffb274..e8a6aa4 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -53,6 +53,14 @@ Struct Resources:
 	For printing struct resources. The 'R' and 'r' specifiers result in a
 	printed resource with ('R') or without ('r') a decoded flags member.

+Physical addresses:
+
+	%pa	0x01234567 or 0x0123456789abcdef
+
+	For printing a phys_addr_t type (and its derivatives, such as
+	resource_size_t) which can vary based on build options, regardless of
+	the width of the CPU data path. Passed by reference.
+
 Raw buffer as a hex string:
 	%*ph	00 01 02  ...  3f
 	%*phC	00:01:02: ... :3f
@@ -150,9 +158,9 @@ s64 SHOULD be printed with %lld/%llx, (long long):
 	printk("%lld", (long long)s64_var);

 If <type> is dependent on a config option for its size (e.g., sector_t,
-blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent
-for its size (e.g., tcflag_t), use a format specifier of its largest
-possible type and explicitly cast to it.  Example:
+blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a
+format specifier of its largest possible type and explicitly cast to it.
+Example:

 	printk("test: sector number/total blocks: %llu/%llu\n",
 		(unsigned long long)sector, (unsigned long long)blockcount);
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 39c99fe..6e62c3f 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1022,6 +1022,7 @@ int kptr_restrict __read_mostly;
  *              N no separator
  *            The maximum supported length is 64 bytes of the input. Consider
  *            to use print_hex_dump() for the larger input.
+ * - 'a' For a phys_addr_t type and its derivative types (passed by reference)
  *
  * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
  * function pointers are really function descriptors, which contain a
@@ -1112,6 +1113,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 			return netdev_feature_string(buf, end, ptr, spec);
 		}
 		break;
+	case 'a':
+		spec.flags |= SPECIAL | SMALL | ZEROPAD;
+		spec.field_width = sizeof(phys_addr_t) * 2 + 2;
+		spec.base = 16;
+		return number(buf, end,
+			      (unsigned long long) *((phys_addr_t *)ptr), spec);
 	}
 	spec.flags |= SMALL;
 	if (spec.field_width == -1) {
--
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