bus: ti-sysc: Check for old incomplete dtb

Let's be nice and show an error on the SoCs about old imcomplete devicetree
if the dtb is still using "simple-bus" instead of "simple-pm-bus" for the
root OCP node.
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/bus/ti-sysc.c

@@ -2858,6 +2858,7 @@ static int sysc_init_soc(struct sysc *ddata)
 	const struct soc_device_attribute *match;
 	struct ti_sysc_platform_data *pdata;
 	unsigned long features = 0;
+	struct device_node *np;
 
 	if (sysc_soc)
 		return 0;
@@ -2878,6 +2879,21 @@ static int sysc_init_soc(struct sysc *ddata)
 	if (match && match->data)
 		sysc_soc->soc = (int)match->data;
 
+	/*
+	 * Check and warn about possible old incomplete dtb. We now want to see
+	 * simple-pm-bus instead of simple-bus in the dtb for genpd using SoCs.
+	 */
+	switch (sysc_soc->soc) {
+	case SOC_AM3:
+	case SOC_AM4:
+		np = of_find_node_by_path("/ocp");
+		WARN_ONCE(np && of_device_is_compatible(np, "simple-bus"),
+			  "ti-sysc: Incomplete old dtb, please update\n");
+		break;
+	default:
+		break;
+	}
+
 	/* Ignore devices that are not available on HS and EMU SoCs */
 	if (!sysc_soc->general_purpose) {
 		switch (sysc_soc->soc) {