lib/vsprintf: Add %pfw conversion specifier for printing fwnode names

Add support for %pfw conversion specifier (with "f" and "P" modifiers) to
support printing full path of the node, including its name ("f") and only
the node's name ("P") in the printk family of functions. The two flags
have equivalent functionality to existing %pOF with the same two modifiers
("f" and "P") on OF based systems. The ability to do the same on ACPI
based systems is added by this patch.

On ACPI based systems the resulting strings look like

	\_SB.PCI0.CIO2.port@1.endpoint@0

where the nodes are separated by a dot (".") and the first three are
ACPI device nodes and the latter two ACPI data nodes.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 0c081edbe97e..a6df7e99e6c9 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -418,6 +418,30 @@ Examples::
 
 Passed by reference.
 
+Fwnode handles
+--------------
+
+::
+
+	%pfw[fP]
+
+For printing information on fwnode handles. The default is to print the full
+node name, including the path. The modifiers are functionally equivalent to
+%pOF above.
+
+	- f - full name of the node, including the path
+	- P - the name of the node including an address (if there is one)
+
+Examples (ACPI)::
+
+	%pfwf	\_SB.PCI0.CIO2.port@1.endpoint@0	- Full node name
+	%pfwP	endpoint@0				- Node name
+
+Examples (OF)::
+
+	%pfwf	/ocp@68000000/i2c@48072000/camera@10/port/endpoint - Full name
+	%pfwP	endpoint				- Node name
+
 Time and date (struct rtc_time)
 -------------------------------