gpio: Add a driver for Sodaville GPIO controller

Sodaville has GPIO controller behind the PCI bus. To my suprissed it is
not the same as on PXA.

The interrupt & gpio chip can be referenced from the device tree like
from any other driver. Unfortunately the driver which uses the gpio
interrupt has to use irq_of_parse_and_map() instead of
platform_get_irq(). The problem is that the platform device (which is
created from the device tree) is most likely created before the
interrupt chip is registered and therefore irq_of_parse_and_map() fails.

In theory the driver works as module. In reality most of the irq
functions are not exported to modules and it is possible that _this_
module is unloaded while the provided irqs are still in use.

Signed-off-by: Hans J. Koch <hjk@linutronix.de>
[torbenh@linutronix.de: make it work after the irq namespace cleanup,
	                add some device tree entries.]
Signed-off-by: Torben Hohn <torbenh@linutronix.de>
[bigeasy@linutronix.de: convert to generic irq & gpio chip]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[grant.likely@secretlab.ca: depend on x86 to avoid irq_domain breakage]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 48 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/gpio/sodaville.txt b/Documentation/devicetree/bindings/gpio/sodaville.txt
new file mode 100644
index 000000000000..563eff22b975
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/sodaville.txt
@@ -0,0 +1,48 @@
+GPIO controller on CE4100 / Sodaville SoCs
+==========================================
+
+The bindings for CE4100's GPIO controller match the generic description
+which is covered by the gpio.txt file in this folder.
+
+The only additional property is the intel,muxctl property which holds the
+value which is written into the MUXCNTL register.
+
+There is no compatible property for now because the driver is probed via
+PCI id (vendor 0x8086 device 0x2e67).
+
+The interrupt specifier consists of two cells encoded as follows:
+ - <1st cell>: The interrupt-number that identifies the interrupt source.
+ - <2nd cell>: The level-sense information, encoded as follows:
+                4 - active high level-sensitive
+                8 - active low level-sensitive
+
+Example of the GPIO device and one user:
+
+        pcigpio: gpio@b,1 {
+                        /* two cells for GPIO and interrupt */
+                        #gpio-cells = <2>;
+                        #interrupt-cells = <2>;
+                        compatible = "pci8086,2e67.2",
+                                           "pci8086,2e67",
+                                           "pciclassff0000",
+                                           "pciclassff00";
+
+                        reg = <0x15900 0x0 0x0 0x0 0x0>;
+                        /* Interrupt line of the gpio device */
+                        interrupts = <15 1>;
+                        /* It is an interrupt and GPIO controller itself */
+                        interrupt-controller;
+                        gpio-controller;
+                        intel,muxctl = <0>;
+        };
+
+        testuser@20 {
+                        compatible = "example,testuser";
+                        /* User the 11th GPIO line as an active high triggered
+                         * level interrupt
+                         */
+                        interrupts = <11 8>;
+                        interrupt-parent = <&pcigpio>;
+                        /* Use this GPIO also with the gpio functions */
+                        gpios = <&pcigpio 11 0>;
+        };