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>

6 files changed, 13 insertions, 28 deletions

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 70aea9c274fe..aecc111fbe73 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1665,6 +1665,7 @@ static void fec_get_mac(struct net_device *ndev)
 {
 	struct fec_enet_private *fep = netdev_priv(ndev);
 	unsigned char *iap, tmpaddr[ETH_ALEN];
+	int ret;
 
 	/*
 	 * try to get mac address in following order:
@@ -1680,9 +1681,9 @@ static void fec_get_mac(struct net_device *ndev)
 	if (!is_valid_ether_addr(iap)) {
 		struct device_node *np = fep->pdev->dev.of_node;
 		if (np) {
-			const char *mac = of_get_mac_address(np);
-			if (!IS_ERR(mac))
-				iap = (unsigned char *) mac;
+			ret = of_get_mac_address(np, tmpaddr);
+			if (!ret)
+				iap = tmpaddr;
 		}
 	}
 
diff --git a/drivers/net/ethernet/freescale/fec_mpc52xx.c b/drivers/net/ethernet/freescale/fec_mpc52xx.c
index b3bad429e03b..02c47658a215 100644
--- a/drivers/net/ethernet/freescale/fec_mpc52xx.c
+++ b/drivers/net/ethernet/freescale/fec_mpc52xx.c
@@ -813,7 +813,6 @@ static int mpc52xx_fec_probe(struct platform_device *op)
 	const u32 *prop;
 	int prop_size;
 	struct device_node *np = op->dev.of_node;
-	const char *mac_addr;
 
 	phys_addr_t rx_fifo;
 	phys_addr_t tx_fifo;
@@ -891,10 +890,8 @@ static int mpc52xx_fec_probe(struct platform_device *op)
 	 *
 	 * First try to read MAC address from DT
 	 */
-	mac_addr = of_get_mac_address(np);
-	if (!IS_ERR(mac_addr)) {
-		ether_addr_copy(ndev->dev_addr, mac_addr);
-	} else {
+	rv = of_get_mac_address(np, ndev->dev_addr);
+	if (rv) {
 		struct mpc52xx_fec __iomem *fec = priv->fec;
 
 		/*
diff --git a/drivers/net/ethernet/freescale/fman/mac.c b/drivers/net/ethernet/freescale/fman/mac.c
index 901749a7a318..46ecb42f2ef8 100644
--- a/drivers/net/ethernet/freescale/fman/mac.c
+++ b/drivers/net/ethernet/freescale/fman/mac.c
@@ -605,7 +605,6 @@ static int mac_probe(struct platform_device *_of_dev)
 	struct platform_device	*of_dev;
 	struct resource		 res;
 	struct mac_priv_s	*priv;
-	const u8		*mac_addr;
 	u32			 val;
 	u8			fman_id;
 	phy_interface_t          phy_if;
@@ -723,11 +722,9 @@ static int mac_probe(struct platform_device *_of_dev)
 	priv->cell_index = (u8)val;
 
 	/* Get the MAC address */
-	mac_addr = of_get_mac_address(mac_node);
-	if (IS_ERR(mac_addr))
+	err = of_get_mac_address(mac_node, mac_dev->addr);
+	if (err)
 		dev_warn(dev, "of_get_mac_address(%pOF) failed\n", mac_node);
-	else
-		ether_addr_copy(mac_dev->addr, mac_addr);
 
 	/* Get the port handles */
 	nph = of_count_phandle_with_args(mac_node, "fsl,fman-ports", NULL);
@@ -853,7 +850,7 @@ static int mac_probe(struct platform_device *_of_dev)
 	if (err < 0)
 		dev_err(dev, "fman_set_mac_active_pause() = %d\n", err);
 
-	if (!IS_ERR(mac_addr))
+	if (!is_zero_ether_addr(mac_dev->addr))
 		dev_info(dev, "FMan MAC address: %pM\n", mac_dev->addr);
 
 	priv->eth_dev = dpaa_eth_add_device(fman_id, mac_dev);
diff --git a/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c b/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
index 78e008b81374..6ee325ad35c5 100644
--- a/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
+++ b/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
@@ -918,7 +918,6 @@ static int fs_enet_probe(struct platform_device *ofdev)
 	const u32 *data;
 	struct clk *clk;
 	int err;
-	const u8 *mac_addr;
 	const char *phy_connection_type;
 	int privsize, len, ret = -ENODEV;
 
@@ -1006,9 +1005,7 @@ static int fs_enet_probe(struct platform_device *ofdev)
 	spin_lock_init(&fep->lock);
 	spin_lock_init(&fep->tx_lock);
 
-	mac_addr = of_get_mac_address(ofdev->dev.of_node);
-	if (!IS_ERR(mac_addr))
-		ether_addr_copy(ndev->dev_addr, mac_addr);
+	of_get_mac_address(ofdev->dev.of_node, ndev->dev_addr);
 
 	ret = fep->ops->allocate_bd(ndev);
 	if (ret)
diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 3ec4d9fddd52..339f9567ef9d 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -640,7 +640,6 @@ static phy_interface_t gfar_get_interface(struct net_device *dev)
 static int gfar_of_init(struct platform_device *ofdev, struct net_device **pdev)
 {
 	const char *model;
-	const void *mac_addr;
 	int err = 0, i;
 	phy_interface_t interface;
 	struct net_device *dev = NULL;
@@ -782,11 +781,8 @@ static int gfar_of_init(struct platform_device *ofdev, struct net_device **pdev)
 	if (stash_len || stash_idx)
 		priv->device_flags |= FSL_GIANFAR_DEV_HAS_BUF_STASHING;
 
-	mac_addr = of_get_mac_address(np);
-
-	if (!IS_ERR(mac_addr)) {
-		ether_addr_copy(dev->dev_addr, mac_addr);
-	} else {
+	err = of_get_mac_address(np, dev->dev_addr);
+	if (err) {
 		eth_hw_addr_random(dev);
 		dev_info(&ofdev->dev, "Using random MAC address: %pM\n", dev->dev_addr);
 	}
diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c
index ef4e2febeb5b..e0936510fa34 100644
--- a/drivers/net/ethernet/freescale/ucc_geth.c
+++ b/drivers/net/ethernet/freescale/ucc_geth.c
@@ -3562,7 +3562,6 @@ static int ucc_geth_probe(struct platform_device* ofdev)
 	struct resource res;
 	int err, ucc_num, max_speed = 0;
 	const unsigned int *prop;
-	const void *mac_addr;
 	phy_interface_t phy_interface;
 	static const int enet_to_speed[] = {
 		SPEED_10, SPEED_10, SPEED_10,
@@ -3733,9 +3732,7 @@ static int ucc_geth_probe(struct platform_device* ofdev)
 		goto err_free_netdev;
 	}
 
-	mac_addr = of_get_mac_address(np);
-	if (!IS_ERR(mac_addr))
-		ether_addr_copy(dev->dev_addr, mac_addr);
+	of_get_mac_address(np, dev->dev_addr);
 
 	ugeth->ug_info = ug_info;
 	ugeth->dev = device;