bus: mvebu-mbus: Introduce device tree binding

This patch adds the most fundamental device-tree initialization.
We only introduce what's required to be able to probe the mvebu-mbus
driver from the DT. Follow-up patches will extend the device tree binding,
allowing to describe static address decoding windows.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/bus/mvebu-mbus.c

@@ -900,3 +900,52 @@ int __init mvebu_mbus_init(const char *soc, phys_addr_t mbuswins_phys_base,
 			sdramwins_phys_base,
 			sdramwins_size);
 }
+
+#ifdef CONFIG_OF
+int __init mvebu_mbus_dt_init(void)
+{
+	struct resource mbuswins_res, sdramwins_res;
+	struct device_node *np, *controller;
+	const struct of_device_id *of_id;
+	const __be32 *prop;
+	int ret;
+
+	np = of_find_matching_node(NULL, of_mvebu_mbus_ids);
+	if (!np) {
+		pr_err("could not find a matching SoC family\n");
+		return -ENODEV;
+	}
+
+	of_id = of_match_node(of_mvebu_mbus_ids, np);
+	mbus_state.soc = of_id->data;
+
+	prop = of_get_property(np, "controller", NULL);
+	if (!prop) {
+		pr_err("required 'controller' property missing\n");
+		return -EINVAL;
+	}
+
+	controller = of_find_node_by_phandle(be32_to_cpup(prop));
+	if (!controller) {
+		pr_err("could not find an 'mbus-controller' node\n");
+		return -ENODEV;
+	}
+
+	if (of_address_to_resource(controller, 0, &mbuswins_res)) {
+		pr_err("cannot get MBUS register address\n");
+		return -EINVAL;
+	}
+
+	if (of_address_to_resource(controller, 1, &sdramwins_res)) {
+		pr_err("cannot get SDRAM register address\n");
+		return -EINVAL;
+	}
+
+	ret = mvebu_mbus_common_init(&mbus_state,
+				     mbuswins_res.start,
+				     resource_size(&mbuswins_res),
+				     sdramwins_res.start,
+				     resource_size(&sdramwins_res));
+	return ret;
+}
+#endif

include/linux/mbus.h

@@ -74,5 +74,6 @@ int mvebu_mbus_del_window(phys_addr_t base, size_t size);
 int mvebu_mbus_init(const char *soc, phys_addr_t mbus_phys_base,
 		    size_t mbus_size, phys_addr_t sdram_phys_base,
 		    size_t sdram_size);
+int mvebu_mbus_dt_init(void);
 
 #endif /* __LINUX_MBUS_H */