of: net: pass the dst buffer to of_get_mac_address()

of_get_mac_address() returns a "const void*" pointer to a MAC address.
Lately, support to fetch the MAC address by an NVMEM provider was added.
But this will only work with platform devices. It will not work with
PCI devices (e.g. of an integrated root complex) and esp. not with DSA
ports.

There is an of_* variant of the nvmem binding which works without
devices. The returned data of a nvmem_cell_read() has to be freed after
use. On the other hand the return of_get_mac_address() points to some
static data without a lifetime. The trick for now, was to allocate a
device resource managed buffer which is then returned. This will only
work if we have an actual device.

Change it, so that the caller of of_get_mac_address() has to supply a
buffer where the MAC address is written to. Unfortunately, this will
touch all drivers which use the of_get_mac_address().

Usually the code looks like:

  const char *addr;
  addr = of_get_mac_address(np);
  if (!IS_ERR(addr))
    ether_addr_copy(ndev->dev_addr, addr);

This can then be simply rewritten as:

  of_get_mac_address(np, ndev->dev_addr);

Sometimes is_valid_ether_addr() is used to test the MAC address.
of_get_mac_address() already makes sure, it just returns a valid MAC
address. Thus we can just test its return code. But we have to be
careful if there are still other sources for the MAC address before the
of_get_mac_address(). In this case we have to keep the
is_valid_ether_addr() call.

The following coccinelle patch was used to convert common cases to the
new style. Afterwards, I've manually gone over the drivers and fixed the
return code variable: either used a new one or if one was already
available use that. Mansour Moufid, thanks for that coccinelle patch!

<spml>
@a@
identifier x;
expression y, z;
@@
- x = of_get_mac_address(y);
+ x = of_get_mac_address(y, z);
  <...
- ether_addr_copy(z, x);
  ...>

@@
identifier a.x;
@@
- if (<+... x ...+>) {}

@@
identifier a.x;
@@
  if (<+... x ...+>) {
      ...
  }
- else {}

@@
identifier a.x;
expression e;
@@
- if (<+... x ...+>@e)
-     {}
- else
+ if (!(e))
      {...}

@@
expression x, y, z;
@@
- x = of_get_mac_address(y, z);
+ of_get_mac_address(y, z);
  ... when != x
</spml>

All drivers, except drivers/net/ethernet/aeroflex/greth.c, were
compile-time tested.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 13 insertions, 22 deletions

diff --git a/drivers/net/ethernet/broadcom/bcm4908_enet.c b/drivers/net/ethernet/broadcom/bcm4908_enet.c
index b7afac5c7ca7..60d908507f51 100644
--- a/drivers/net/ethernet/broadcom/bcm4908_enet.c
+++ b/drivers/net/ethernet/broadcom/bcm4908_enet.c
@@ -686,7 +686,6 @@ static int bcm4908_enet_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct net_device *netdev;
 	struct bcm4908_enet *enet;
-	const u8 *mac;
 	int err;
 
 	netdev = devm_alloc_etherdev(dev, sizeof(*enet));
@@ -716,10 +715,8 @@ static int bcm4908_enet_probe(struct platform_device *pdev)
 		return err;
 
 	SET_NETDEV_DEV(netdev, &pdev->dev);
-	mac = of_get_mac_address(dev->of_node);
-	if (!IS_ERR(mac))
-		ether_addr_copy(netdev->dev_addr, mac);
-	else
+	err = of_get_mac_address(dev->of_node, netdev->dev_addr);
+	if (err)
 		eth_hw_addr_random(netdev);
 	netdev->netdev_ops = &bcm4908_enet_netdev_ops;
 	netdev->min_mtu = ETH_ZLEN;
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
index 777bbf6d2586..d9f0f0df8f7b 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -2457,7 +2457,6 @@ static int bcm_sysport_probe(struct platform_device *pdev)
 	struct bcm_sysport_priv *priv;
 	struct device_node *dn;
 	struct net_device *dev;
-	const void *macaddr;
 	u32 txq, rxq;
 	int ret;
 
@@ -2552,12 +2551,10 @@ static int bcm_sysport_probe(struct platform_device *pdev)
 	}
 
 	/* Initialize netdevice members */
-	macaddr = of_get_mac_address(dn);
-	if (IS_ERR(macaddr)) {
+	ret = of_get_mac_address(dn, dev->dev_addr);
+	if (ret) {
 		dev_warn(&pdev->dev, "using random Ethernet MAC\n");
 		eth_hw_addr_random(dev);
-	} else {
-		ether_addr_copy(dev->dev_addr, macaddr);
 	}
 
 	SET_NETDEV_DEV(dev, &pdev->dev);
diff --git a/drivers/net/ethernet/broadcom/bgmac-bcma.c b/drivers/net/ethernet/broadcom/bgmac-bcma.c
index a5fd161ab5ee..85fa0ab7201c 100644
--- a/drivers/net/ethernet/broadcom/bgmac-bcma.c
+++ b/drivers/net/ethernet/broadcom/bgmac-bcma.c
@@ -115,7 +115,7 @@ static int bgmac_probe(struct bcma_device *core)
 	struct ssb_sprom *sprom = &core->bus->sprom;
 	struct mii_bus *mii_bus;
 	struct bgmac *bgmac;
-	const u8 *mac = NULL;
+	const u8 *mac;
 	int err;
 
 	bgmac = bgmac_alloc(&core->dev);
@@ -128,11 +128,10 @@ static int bgmac_probe(struct bcma_device *core)
 
 	bcma_set_drvdata(core, bgmac);
 
-	if (bgmac->dev->of_node)
-		mac = of_get_mac_address(bgmac->dev->of_node);
+	err = of_get_mac_address(bgmac->dev->of_node, bgmac->net_dev->dev_addr);
 
 	/* If no MAC address assigned via device tree, check SPROM */
-	if (IS_ERR_OR_NULL(mac)) {
+	if (err) {
 		switch (core->core_unit) {
 		case 0:
 			mac = sprom->et0mac;
@@ -149,10 +148,9 @@ static int bgmac_probe(struct bcma_device *core)
 			err = -ENOTSUPP;
 			goto err;
 		}
+		ether_addr_copy(bgmac->net_dev->dev_addr, mac);
 	}
 
-	ether_addr_copy(bgmac->net_dev->dev_addr, mac);
-
 	/* On BCM4706 we need common core to access PHY */
 	if (core->id.id == BCMA_CORE_4706_MAC_GBIT &&
 	    !core->bus->drv_gmac_cmn.core) {
diff --git a/drivers/net/ethernet/broadcom/bgmac-platform.c b/drivers/net/ethernet/broadcom/bgmac-platform.c
index f37f1c58f368..9834b77cf4b6 100644
--- a/drivers/net/ethernet/broadcom/bgmac-platform.c
+++ b/drivers/net/ethernet/broadcom/bgmac-platform.c
@@ -173,7 +173,7 @@ static int bgmac_probe(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	struct bgmac *bgmac;
 	struct resource *regs;
-	const u8 *mac_addr;
+	int ret;
 
 	bgmac = bgmac_alloc(&pdev->dev);
 	if (!bgmac)
@@ -192,11 +192,10 @@ static int bgmac_probe(struct platform_device *pdev)
 	bgmac->dev = &pdev->dev;
 	bgmac->dma_dev = &pdev->dev;
 
-	mac_addr = of_get_mac_address(np);
-	if (!IS_ERR(mac_addr))
-		ether_addr_copy(bgmac->net_dev->dev_addr, mac_addr);
-	else
-		dev_warn(&pdev->dev, "MAC address not present in device tree\n");
+	ret = of_get_mac_address(np, bgmac->net_dev->dev_addr);
+	if (ret)
+		dev_warn(&pdev->dev,
+			 "MAC address not present in device tree\n");
 
 	bgmac->irq = platform_get_irq(pdev, 0);
 	if (bgmac->irq < 0)