ARM: 9480/1: entry: expand comment in __switch_tografted

As per discussion between the developers in the mail thread
linked, expand the comment in __switch_to so that readers
of the code understand what is going on.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 48 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/pmem/pmem-region.yaml b/Documentation/devicetree/bindings/pmem/pmem-region.yaml
new file mode 100644
index 000000000..bd0f0c793
--- /dev/null
+++ b/Documentation/devicetree/bindings/pmem/pmem-region.yaml
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pmem-region.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+maintainers:
+  - Oliver O'Halloran <oohall@gmail.com>
+
+title: Persistent Memory Regions
+
+description: |
+  Persistent memory refers to a class of memory devices that are:
+
+    a) Usable as main system memory (i.e. cacheable), and
+    b) Retain their contents across power failure.
+
+  Given b) it is best to think of persistent memory as a kind of memory mapped
+  storage device. To ensure data integrity the operating system needs to manage
+  persistent regions separately to the normal memory pool. To aid with that this
+  binding provides a standardised interface for discovering where persistent
+  memory regions exist inside the physical address space.
+
+properties:
+  compatible:
+    const: pmem-region
+
+  reg:
+    maxItems: 1
+
+  volatile:
+    description:
+      Indicates the region is volatile (non-persistent) and the OS can skip
+      cache flushes for writes
+    type: boolean
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    pmem@5000 {
+        compatible = "pmem-region";
+        reg = <0x00005000 0x00001000>;
+    };