mailbox: Allow controller specific mapping using fwnode

Introduce optional fw_node() callback which allows a mailbox controller
driver to provide controller specific mapping using fwnode.

The Linux OF framework already implements fwnode operations for the
Linux DD framework so the fw_xlate() callback works fine with device
tree as well.

Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Link: https://lore.kernel.org/r/20250818040920.272664-6-apatel@ventanamicro.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>

drivers/mailbox/mailbox.c

@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/property.h>
 #include <linux/spinlock.h>
 
 #include "mailbox.h"
@@ -383,34 +384,56 @@ EXPORT_SYMBOL_GPL(mbox_bind_client);
  */
 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
 {
-	struct device *dev = cl->dev;
+	struct fwnode_reference_args fwspec;
+	struct fwnode_handle *fwnode;
 	struct mbox_controller *mbox;
 	struct of_phandle_args spec;
 	struct mbox_chan *chan;
+	struct device *dev;
+	unsigned int i;
 	int ret;
 
-	if (!dev || !dev->of_node) {
+	dev = cl->dev;
-		pr_debug("%s: No owner device node\n", __func__);
+	if (!dev) {
+		pr_debug("No owner device\n");
 		return ERR_PTR(-ENODEV);
 	}
 
-	ret = of_parse_phandle_with_args(dev->of_node, "mboxes", "#mbox-cells",
+	fwnode = dev_fwnode(dev);
-					 index, &spec);
+	if (!fwnode) {
+		dev_dbg(dev, "No owner fwnode\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	ret = fwnode_property_get_reference_args(fwnode, "mboxes", "#mbox-cells",
+						 0, index, &fwspec);
 	if (ret) {
-		dev_err(dev, "%s: can't parse \"mboxes\" property\n", __func__);
+		dev_err(dev, "%s: can't parse \"%s\" property\n", __func__, "mboxes");
 		return ERR_PTR(ret);
 	}
 
+	spec.np = to_of_node(fwspec.fwnode);
+	spec.args_count = fwspec.nargs;
+	for (i = 0; i < spec.args_count; i++)
+		spec.args[i] = fwspec.args[i];
+
 	scoped_guard(mutex, &con_mutex) {
 		chan = ERR_PTR(-EPROBE_DEFER);
-		list_for_each_entry(mbox, &mbox_cons, node)
+		list_for_each_entry(mbox, &mbox_cons, node) {
-			if (mbox->dev->of_node == spec.np) {
+			if (device_match_fwnode(mbox->dev, fwspec.fwnode)) {
+				if (mbox->fw_xlate) {
+					chan = mbox->fw_xlate(mbox, &fwspec);
+					if (!IS_ERR(chan))
+						break;
+				} else if (mbox->of_xlate) {
 					chan = mbox->of_xlate(mbox, &spec);
 					if (!IS_ERR(chan))
 						break;
 				}
+			}
+		}
 
-		of_node_put(spec.np);
+		fwnode_handle_put(fwspec.fwnode);
 
 		if (IS_ERR(chan))
 			return chan;
@@ -427,15 +450,8 @@ EXPORT_SYMBOL_GPL(mbox_request_channel);
 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
 					      const char *name)
 {
-	struct device_node *np = cl->dev->of_node;
+	int index = device_property_match_string(cl->dev, "mbox-names", name);
-	int index;
 
-	if (!np) {
-		dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
-		return ERR_PTR(-EINVAL);
-	}
-
-	index = of_property_match_string(np, "mbox-names", name);
 	if (index < 0) {
 		dev_err(cl->dev, "%s() could not locate channel named \"%s\"\n",
 			__func__, name);
@@ -470,9 +486,8 @@ void mbox_free_channel(struct mbox_chan *chan)
 }
 EXPORT_SYMBOL_GPL(mbox_free_channel);
 
-static struct mbox_chan *
+static struct mbox_chan *fw_mbox_index_xlate(struct mbox_controller *mbox,
-of_mbox_index_xlate(struct mbox_controller *mbox,
+					     const struct fwnode_reference_args *sp)
-		    const struct of_phandle_args *sp)
 {
 	int ind = sp->args[0];
 
@@ -523,8 +538,8 @@ int mbox_controller_register(struct mbox_controller *mbox)
 		spin_lock_init(&chan->lock);
 	}
 
-	if (!mbox->of_xlate)
+	if (!mbox->fw_xlate && !mbox->of_xlate)
-		mbox->of_xlate = of_mbox_index_xlate;
+		mbox->fw_xlate = fw_mbox_index_xlate;
 
 	scoped_guard(mutex, &con_mutex)
 		list_add_tail(&mbox->node, &mbox_cons);

include/linux/mailbox_controller.h

@@ -66,6 +66,7 @@ struct mbox_chan_ops {
  *			no interrupt rises. Ignored if 'txdone_irq' is set.
  * @txpoll_period:	If 'txdone_poll' is in effect, the API polls for
  *			last TX's status after these many millisecs
+ * @fw_xlate:		Controller driver specific mapping of channel via fwnode
  * @of_xlate:		Controller driver specific mapping of channel via DT
  * @poll_hrt:		API private. hrtimer used to poll for TXDONE on all
  *			channels.
@@ -79,6 +80,8 @@ struct mbox_controller {
 	bool txdone_irq;
 	bool txdone_poll;
 	unsigned txpoll_period;
+	struct mbox_chan *(*fw_xlate)(struct mbox_controller *mbox,
+				      const struct fwnode_reference_args *sp);
 	struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
 				      const struct of_phandle_args *sp);
 	/* Internal to API */