mdio: mux: Enhanced MDIO mux framework for integrated multiplexers

An integrated multiplexer uses same address space for
"muxed bus selection" and "generation of mdio transaction"
hence its good to register parent bus from mux driver.

Hence added a mechanism where mux driver could register a
parent bus and pass it down to framework via mdio_mux_init api.
Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/mdio-mux-gpio.c

@@ -55,7 +55,7 @@ static int mdio_mux_gpio_probe(struct platform_device *pdev)
 		return PTR_ERR(s->gpios);
 
 	r = mdio_mux_init(&pdev->dev,
-			  mdio_mux_gpio_switch_fn, &s->mux_handle, s);
+			  mdio_mux_gpio_switch_fn, &s->mux_handle, s, NULL);
 
 	if (r != 0) {
 		gpiod_put_array(s->gpios);

drivers/net/phy/mdio-mux-mmioreg.c

@@ -126,7 +126,7 @@ static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
 	}
 
 	ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
-			    &s->mux_handle, s);
+			    &s->mux_handle, s, NULL);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
 			np->full_name);

drivers/net/phy/mdio-mux.c

@@ -89,7 +89,8 @@ static int parent_count;
 int mdio_mux_init(struct device *dev,
 		  int (*switch_fn)(int cur, int desired, void *data),
 		  void **mux_handle,
-		  void *data)
+		  void *data,
+		  struct mii_bus *mux_bus)
 {
 	struct device_node *parent_bus_node;
 	struct device_node *child_bus_node;
@@ -101,22 +102,28 @@ int mdio_mux_init(struct device *dev,
 	if (!dev->of_node)
 		return -ENODEV;
 
-	parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
+	if (!mux_bus) {
+		parent_bus_node = of_parse_phandle(dev->of_node,
+						   "mdio-parent-bus", 0);
 
 		if (!parent_bus_node)
 			return -ENODEV;
 
+		parent_bus = of_mdio_find_bus(parent_bus_node);
+		if (!parent_bus) {
+			ret_val = -EPROBE_DEFER;
+			goto err_parent_bus;
+		}
+	} else {
+		parent_bus = mux_bus;
+	}
+
 	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
 	if (pb == NULL) {
 		ret_val = -ENOMEM;
 		goto err_parent_bus;
 	}
 
-	parent_bus = of_mdio_find_bus(parent_bus_node);
-	if (parent_bus == NULL) {
-		ret_val = -EPROBE_DEFER;
-		goto err_parent_bus;
-	}
 
 	pb->switch_data = data;
 	pb->switch_fn = switch_fn;
@@ -177,6 +184,7 @@ int mdio_mux_init(struct device *dev,
 	put_device(&pb->mii_bus->dev);
 
 err_parent_bus:
+	if (!mux_bus)
 		of_node_put(parent_bus_node);
 	return ret_val;
 }

include/linux/mdio-mux.h

@@ -10,11 +10,13 @@
 #ifndef __LINUX_MDIO_MUX_H
 #define __LINUX_MDIO_MUX_H
 #include <linux/device.h>
+#include <linux/phy.h>
 
 int mdio_mux_init(struct device *dev,
 		  int (*switch_fn) (int cur, int desired, void *data),
 		  void **mux_handle,
-		  void *data);
+		  void *data,
+		  struct mii_bus *mux_bus);
 
 void mdio_mux_uninit(void *mux_handle);