printf: Add print format (%pra) for struct range

The use of struct range in the CXL subsystem is growing.  In particular,
the addition of Dynamic Capacity devices uses struct range in a number
of places which are reported in debug and error messages.

To wit requiring the printing of the start/end fields in each print
became cumbersome.  Dan Williams mentions in [1] that it might be time
to have a print specifier for struct range similar to struct resource.

A few alternatives were considered including '%par', '%r', and '%pn'.
%pra follows that struct range is similar to struct resource (%p[rR])
but needs to be different.  Based on discussions with Petr and Andy
'%pra' was chosen.[2]

Andy also suggested to keep the range prints similar to struct resource
though combined code.  Add hex_range() to handle printing for both
pointer types.

Finally introduce DEFINE_RANGE() as a parallel to DEFINE_RES_*() and use
it in the tests.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: open list <linux-kernel@vger.kernel.org>
Link: https://lore.kernel.org/all/663922b475e50_d54d72945b@dwillia2-xfh.jf.intel.com.notmuch/ [1]
Link: https://lore.kernel.org/all/66cea3bf3332f_f937b29424@iweiny-mobl.notmuch/ [2]
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20241025-cxl-pra-v2-3-123a825daba2@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/test_printf.c b/lib/test_printf.c
index 5afdf5efc627..59dbe4f9a4cb 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -433,6 +433,22 @@ struct_resource(void)
 }
 
 static void __init
+struct_range(void)
+{
+	struct range test_range = DEFINE_RANGE(0xc0ffee00ba5eba11,
+					       0xc0ffee00ba5eba11);
+	test("[range 0xc0ffee00ba5eba11]", "%pra", &test_range);
+
+	test_range = DEFINE_RANGE(0xc0ffee, 0xba5eba11);
+	test("[range 0x0000000000c0ffee-0x00000000ba5eba11]",
+	     "%pra", &test_range);
+
+	test_range = DEFINE_RANGE(0xba5eba11, 0xc0ffee);
+	test("[range 0x00000000ba5eba11-0x0000000000c0ffee]",
+	     "%pra", &test_range);
+}
+
+static void __init
 addr(void)
 {
 }
@@ -807,6 +823,7 @@ test_pointer(void)
 	symbol_ptr();
 	kernel_ptr();
 	struct_resource();
+	struct_range();
 	addr();
 	escaped_str();
 	hex_string();