remoteproc: ti_k3_m4: add ti,no-auto-boot DT property support

Add a new optional boolean device tree property 'ti,no-auto-boot' for
the TI K3 M4F remoteproc driver. When present, this property disables
automatic firmware loading and booting at probe time by setting the
rproc->auto_boot flag to false.

This is useful in scenarios where the M4F firmware depends on resources
that are only available after the filesystem is mounted (e.g. firmware
files in /lib/firmware). In such cases, an external driver such as
'wago,m4-led-wrapper' can explicitly call rproc_boot() once all
dependencies are satisfied.

The corresponding YAML binding documentation is updated to describe the
new property and its intended use case.

Signed-off-by: Heinrich Toews <ht@twx-software.de>

Documentation/devicetree/bindings/remoteproc/ti,k3-m4f-rproc.yaml

@@ -50,6 +50,14 @@ properties:
     maxItems: 1
     description: Name of firmware to load for the M4F core
 
+  ti,no-auto-boot:
+    type: boolean
+    description:
+      If present, the remoteproc will not automatically load and boot the
+      M4F firmware at probe time. Firmware loading is then delegated to an
+      external driver (e.g. wago,m4-led-wrapper) that calls rproc_boot()
+      explicitly once the filesystem is available.
+
   mboxes:
     description:
       OMAP Mailbox specifier denoting the sub-mailbox, to be used for

drivers/remoteproc/ti_k3_m4_remoteproc.c

@@ -899,6 +899,7 @@ static int k3_m4_rproc_probe(struct platform_device *pdev)
 
 	rproc->has_iommu = false;
 	rproc->recovery_disabled = true;
+	rproc->auto_boot = !of_property_read_bool(np, "ti,no-auto-boot");
 	if (data->uses_lreset) {
 		rproc->ops->prepare = k3_m4_rproc_prepare;
 		rproc->ops->unprepare = k3_m4_rproc_unprepare;