Linux-libre 4.7.1-gnupck-4.7.1-gnu

1 files changed, 26 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 069cdf6f9..68d28f62a 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -131,6 +131,13 @@ Every GPIO controller node must contain both an empty "gpio-controller"
 property, and a #gpio-cells integer property, which indicates the number of
 cells in a gpio-specifier.
 
+Some system-on-chips (SoCs) use the concept of GPIO banks. A GPIO bank is an
+instance of a hardware IP core on a silicon die, usually exposed to the
+programmer as a coherent range of I/O addresses. Usually each such bank is
+exposed in the device tree as an individual gpio-controller node, reflecting
+the fact that the hardware was synthesized by reusing the same IP block a
+few times over.
+
 Optionally, a GPIO controller may have a "ngpios" property. This property
 indicates the number of in-use slots of available slots for GPIOs. The
 typical example is something like this: the hardware register is 32 bits
@@ -145,6 +152,21 @@ additional bitmask is needed to specify which GPIOs are actually in use,
 and which are dummies. The bindings for this case has not yet been
 specified, but should be specified if/when such hardware appears.
 
+Optionally, a GPIO controller may have a "gpio-line-names" property. This is
+an array of strings defining the names of the GPIO lines going out of the
+GPIO controller. This name should be the most meaningful producer name
+for the system, such as a rail name indicating the usage. Package names
+such as pin name are discouraged: such lines have opaque names (since they
+are by definition generic purpose) and such names are usually not very
+helpful. For example "MMC-CD", "Red LED Vdd" and "ethernet reset" are
+reasonable line names as they describe what the line is used for. "GPIO0"
+is not a good name to give to a GPIO line. Placeholders are discouraged:
+rather use the "" (blank string) if the use of the GPIO line is undefined
+in your design. The names are assigned starting from line offset 0 from
+left to right from the passed array. An incomplete array (where the number
+of passed named are less than ngpios) will still be used up until the last
+provided valid line index.
+
 Example:
 
 gpio-controller@00000000 {
@@ -153,6 +175,10 @@ gpio-controller@00000000 {
 	gpio-controller;
 	#gpio-cells = <2>;
 	ngpios = <18>;
+	gpio-line-names = "MMC-CD", "MMC-WP", "VDD eth", "RST eth", "LED R",
+		"LED G", "LED B", "Col A", "Col B", "Col C", "Col D",
+		"Row A", "Row B", "Row C", "Row D", "NMI button",
+		"poweroff", "reset";
 }
 
 The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism