dummy netdev: Allow user to attach PHY to dummy device

This patch provides the option for the user to specify a PHY device name
(as found in /sys/bus/mdio_bus/devices/) which should be associated
with the dummy device.

The user can then use the regular SIOCGMIIREG/SIOCSMIIREG ioctl's to
get/set registers on the PHY (or other devices) attached to the mdio_bus
of the given PHY.

This is used in cases where you have PHY devices (like e.g. an ethernet
witch) in the hardware which are attached to an mdio_bus that doesn't
serve a PHY attached to an actual real ethernet device (MAC).

Signed-off-by: Harald Welte <laforge@gnumonks.org>

drivers/net/dummy.c

@@ -40,8 +40,14 @@
 
 #define DRV_NAME	"dummy"
 #define DRV_VERSION	"1.0"
+#define MAX_DUMMIES	6
 
 static int numdummies = 1;
+static char *phy_name[MAX_DUMMIES];
+
+struct dummydev_priv {
+	struct phy_device *phydev;
+};
 
 /* fake multicast ability */
 static void set_multicast_list(struct net_device *dev)
@@ -112,6 +118,16 @@ static int dummy_change_carrier(struct net_device *dev, bool new_carrier)
 	return 0;
 }
 
+static int dummy_dev_ioctl(struct net_device *ndev, struct ifreq *ifrq, int cmd)
+{
+	struct dummydev_priv *priv = netdev_priv(ndev);
+
+	if (priv->phydev)
+		return phy_mii_ioctl(priv->phydev, ifrq, cmd);
+	else
+		return -EOPNOTSUPP;
+}
+
 static const struct net_device_ops dummy_netdev_ops = {
 	.ndo_init		= dummy_dev_init,
 	.ndo_uninit		= dummy_dev_uninit,
@@ -121,6 +137,7 @@ static const struct net_device_ops dummy_netdev_ops = {
 	.ndo_set_mac_address	= eth_mac_addr,
 	.ndo_get_stats64	= dummy_get_stats64,
 	.ndo_change_carrier	= dummy_change_carrier,
+	.ndo_do_ioctl		= dummy_dev_ioctl,
 };
 
 static void dummy_get_drvinfo(struct net_device *dev,
@@ -176,17 +193,54 @@ static struct rtnl_link_ops dummy_link_ops __read_mostly = {
 /* Number of dummy devices to be set up by this module. */
 module_param(numdummies, int, 0);
 MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
+module_param_array(phy_name, charp, NULL, 0444);
+MODULE_PARM_DESC(phy_name, "Attach a PHY with given name to the net_device");
+
+static int match_first_device(struct device *dev, void *data)
+{
+	const char *name = data;
+	printk(KERN_INFO "Checking PHY bus device %p(%s)\n", dev, dev_name(dev));
+	return !strcmp(dev_name(dev), name);
+}
+
+
+static struct device *get_mdio_by_name(const char *name)
+{
+	struct device *phy;
+	phy = bus_find_device(&mdio_bus_type, NULL, (void *)name,
+				match_first_device);
+	printk(KERN_INFO "Found PHY bus device at %p\n", phy);
+	return phy;
+}
 
-static int __init dummy_init_one(void)
+static int __init dummy_init_one(int i)
 {
+	struct device *pdev;
 	struct net_device *dev_dummy;
+	struct dummydev_priv *priv;
 	int err;
 
-	dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_UNKNOWN, dummy_setup);
+	dev_dummy = alloc_netdev(sizeof(struct dummydev_priv), "dummy%d",
+				 NET_NAME_UNKNOWN, dummy_setup);
 	if (!dev_dummy)
 		return -ENOMEM;
 
+	priv = netdev_priv(dev_dummy);
+
 	dev_dummy->rtnl_link_ops = &dummy_link_ops;
+
+	if (i < MAX_DUMMIES && phy_name[i]) {
+		/* find + attach PHY according to name given as module
+		 * parameter */
+		pdev = get_mdio_by_name(phy_name[i]);
+		if (!pdev) {
+			dev_err(&dev_dummy->dev, "Cannot find PHY '%s'\n", phy_name[i]);
+			err = -EINVAL;
+			goto err;
+		}
+		priv->phydev = to_phy_device(pdev);
+	}
+
 	err = register_netdevice(dev_dummy);
 	if (err < 0)
 		goto err;
@@ -207,7 +261,7 @@ static int __init dummy_init_module(void)
 		goto out;
 
 	for (i = 0; i < numdummies && !err; i++) {
-		err = dummy_init_one();
+		err = dummy_init_one(i);
 		cond_resched();
 	}
 	if (err < 0)