Document the device-tree entries for the operator panel

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/doc/device-tree/ibm,opal/oppanel.txt b/doc/device-tree/ibm,opal/oppanel.txt
new file mode 100644
index 0000000..74a4d09
--- /dev/null
+++ b/doc/device-tree/ibm,opal/oppanel.txt
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+Operator Panel (oppanel)
+------------------------
+
+oppanel {
+        compatible = "ibm,opal-oppanel";
+        #lines = <0x2>;
+        #length = <0x10>;
+};
+
+The Operator Panel is a device for displaying small amounts of textual
+data to an administrator. On IBM POWER8 systems with an FSP, this is a
+small 16x2 LCD panel that can be viewed either from the Web UI of the FSP
+(known as ASM) or by physically going to the machine and looking at the
+panel.
+
+The operator panel does not have to be present.
+
+If it is, there are OPAL calls to read and write to it.
+
+The device tree entry is so that the host OS knows the size of the panel
+and can pass buffers of the appropriate size to the OPAL calls.