metag: Internal and external irqchips

Meta core internal interrupts (from HWSTATMETA and friends) are vectored
onto the TR1 core trigger for the current thread. This is demultiplexed
in irq-metag.c to individual Linux IRQs for each internal interrupt.

External SoC interrupts (from HWSTATEXT and friends) are vectored onto
the TR2 core trigger for the current thread. This is demultiplexed in
irq-metag-ext.c to individual Linux IRQs for each external SoC interrupt.
The external irqchip has devicetree bindings for configuring the number
of irq banks and the type of masking available.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Cc: Dom Cobley <popcornmix@gmail.com>
Cc: Simon Arlott <simon@fire.lp0.eu>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-doc@vger.kernel.org

1 files changed, 82 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/metag/meta-intc.txt b/Documentation/devicetree/bindings/metag/meta-intc.txt
new file mode 100644
index 000000000000..8c47dcbfabc6
--- /dev/null
+++ b/Documentation/devicetree/bindings/metag/meta-intc.txt
@@ -0,0 +1,82 @@
+* Meta External Trigger Controller Binding
+
+This binding specifies what properties must be available in the device tree
+representation of a Meta external trigger controller.
+
+Required properties:
+
+    - compatible: Specifies the compatibility list for the interrupt controller.
+      The type shall be <string> and the value shall include "img,meta-intc".
+
+    - num-banks: Specifies the number of interrupt banks (each of which can
+      handle 32 interrupt sources).
+
+    - interrupt-controller: The presence of this property identifies the node
+      as an interupt controller. No property value shall be defined.
+
+    - #interrupt-cells: Specifies the number of cells needed to encode an
+      interrupt source. The type shall be a <u32> and the value shall be 2.
+
+    - #address-cells: Specifies the number of cells needed to encode an
+      address. The type shall be <u32> and the value shall be 0. As such,
+      'interrupt-map' nodes do not have to specify a parent unit address.
+
+Optional properties:
+
+    - no-mask: The controller doesn't have any mask registers.
+
+* Interrupt Specifier Definition
+
+  Interrupt specifiers consists of 2 cells encoded as follows:
+
+    - <1st-cell>: The interrupt-number that identifies the interrupt source.
+
+    - <2nd-cell>: The Linux interrupt flags containing level-sense information,
+                  encoded as follows:
+                    1 = edge triggered
+                    4 = level-sensitive
+
+* Examples
+
+Example 1:
+
+        /*
+         * Meta external trigger block
+         */
+        intc: intc {
+                // This is an interrupt controller node.
+                interrupt-controller;
+
+                // No address cells so that 'interrupt-map' nodes which
+                // reference this interrupt controller node do not need a parent
+                // address specifier.
+                #address-cells = <0>;
+
+                // Two cells to encode interrupt sources.
+                #interrupt-cells = <2>;
+
+                // Number of interrupt banks
+                num-banks = <2>;
+
+                // No HWMASKEXT is available (specify on Chorus2 and Comet ES1)
+                no-mask;
+
+                // Compatible with Meta hardware trigger block.
+                compatible = "img,meta-intc";
+        };
+
+Example 2:
+
+        /*
+         * An interrupt generating device that is wired to a Meta external
+         * trigger block.
+         */
+        uart1: uart@0x02004c00 {
+                // Interrupt source '5' that is level-sensitive.
+                // Note that there are only two cells as specified in the
+                // interrupt parent's '#interrupt-cells' property.
+                interrupts = <5 4 /* level */>;
+
+                // The interrupt controller that this device is wired to.
+                interrupt-parent = <&intc>;
+        };