[PATCH v2 1/4] dt-bindings: firmware: qcom,scm: Add minidump SRAM property

[Mukesh Ojha]

On most Qualcomm SoCs where minidump is supported, a word in always-on
SRAM is shared between the kernel and boot firmware. Before DDR is
initialised on the warm reset following a crash, firmware reads this
word to decide if minidump is enabled and collect a minidump and where
 to deliver it (USB upload to a host, or save to local storage).

Add a 'sram' property to the SCM binding to describe a region in
always-on SRAM where the minidump download destination value could be
written. Boot firmware reads it before DDR is initialised on a warm
reset to decide where to store the minidump either to host PC or to
on device storage.

Signed-off-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>
---
 .../devicetree/bindings/firmware/qcom,scm.yaml   | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/firmware/qcom,scm.yaml b/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
index 25f62bacbc91..27422d00b8fc 100644
--- a/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
+++ b/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
@@ -129,6 +129,13 @@ properties:
           - description: offset of the download mode control register
     description: TCSR hardware block
 
+  sram:
+    description:
+      Phandle to a region in always-on SRAM used to store the download
+      mode value for boot firmware to read before DDR is initialised on
+      the next warm reset.
+    maxItems: 1
+
 allOf:
   # Clocks
   - if:
@@ -250,3 +257,12 @@ examples:
             clock-names = "core", "bus", "iface";
         };
     };
+
+  - |
+    firmware {
+        scm {
+            compatible = "qcom,scm-kaanapali", "qcom,scm";
+            sram = <&minidump_config>;
+            #reset-cells = <1>;
+        };
+    };
-- 
2.53.0