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>

5 files changed, 17 insertions, 31 deletions

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index 638d7b03be4b..6a67b026df0b 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -1824,7 +1824,6 @@ static int am65_cpsw_nuss_init_slave_ports(struct am65_cpsw_common *common)
 
 	for_each_child_of_node(node, port_np) {
 		struct am65_cpsw_port *port;
-		const void *mac_addr;
 		u32 port_id;
 
 		/* it is not a slave port node, continue */
@@ -1903,15 +1902,15 @@ static int am65_cpsw_nuss_init_slave_ports(struct am65_cpsw_common *common)
 			return ret;
 		}
 
-		mac_addr = of_get_mac_address(port_np);
-		if (!IS_ERR(mac_addr)) {
-			ether_addr_copy(port->slave.mac_addr, mac_addr);
-		} else if (am65_cpsw_am654_get_efuse_macid(port_np,
-							   port->port_id,
-							   port->slave.mac_addr) ||
-			   !is_valid_ether_addr(port->slave.mac_addr)) {
-			random_ether_addr(port->slave.mac_addr);
-			dev_err(dev, "Use random MAC address\n");
+		ret = of_get_mac_address(port_np, port->slave.mac_addr);
+		if (ret) {
+			am65_cpsw_am654_get_efuse_macid(port_np,
+							port->port_id,
+							port->slave.mac_addr);
+			if (!is_valid_ether_addr(port->slave.mac_addr)) {
+				random_ether_addr(port->slave.mac_addr);
+				dev_err(dev, "Use random MAC address\n");
+			}
 		}
 	}
 	of_node_put(node);
diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index 074702af3dc6..c0cd7de88316 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -1296,7 +1296,6 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
 
 	for_each_available_child_of_node(node, slave_node) {
 		struct cpsw_slave_data *slave_data = data->slave_data + i;
-		const void *mac_addr = NULL;
 		int lenp;
 		const __be32 *parp;
 
@@ -1368,10 +1367,8 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
 		}
 
 no_phy_slave:
-		mac_addr = of_get_mac_address(slave_node);
-		if (!IS_ERR(mac_addr)) {
-			ether_addr_copy(slave_data->mac_addr, mac_addr);
-		} else {
+		ret = of_get_mac_address(slave_node, slave_data->mac_addr);
+		if (ret) {
 			ret = ti_cm_get_macid(&pdev->dev, i,
 					      slave_data->mac_addr);
 			if (ret)
diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
index 0751f77de2c7..69b7a4e0220a 100644
--- a/drivers/net/ethernet/ti/cpsw_new.c
+++ b/drivers/net/ethernet/ti/cpsw_new.c
@@ -1257,7 +1257,6 @@ static int cpsw_probe_dt(struct cpsw_common *cpsw)
 
 	for_each_child_of_node(tmp_node, port_np) {
 		struct cpsw_slave_data *slave_data;
-		const void *mac_addr;
 		u32 port_id;
 
 		ret = of_property_read_u32(port_np, "reg", &port_id);
@@ -1316,10 +1315,8 @@ static int cpsw_probe_dt(struct cpsw_common *cpsw)
 			goto err_node_put;
 		}
 
-		mac_addr = of_get_mac_address(port_np);
-		if (!IS_ERR(mac_addr)) {
-			ether_addr_copy(slave_data->mac_addr, mac_addr);
-		} else {
+		ret = of_get_mac_address(port_np, slave_data->mac_addr);
+		if (ret) {
 			ret = ti_cm_get_macid(dev, port_id - 1,
 					      slave_data->mac_addr);
 			if (ret)
diff --git a/drivers/net/ethernet/ti/davinci_emac.c b/drivers/net/ethernet/ti/davinci_emac.c
index c7031e1960d4..14e7da7d302f 100644
--- a/drivers/net/ethernet/ti/davinci_emac.c
+++ b/drivers/net/ethernet/ti/davinci_emac.c
@@ -1687,7 +1687,6 @@ davinci_emac_of_get_pdata(struct platform_device *pdev, struct emac_priv *priv)
 	const struct of_device_id *match;
 	const struct emac_platform_data *auxdata;
 	struct emac_platform_data *pdata = NULL;
-	const u8 *mac_addr;
 
 	if (!IS_ENABLED(CONFIG_OF) || !pdev->dev.of_node)
 		return dev_get_platdata(&pdev->dev);
@@ -1699,11 +1698,8 @@ davinci_emac_of_get_pdata(struct platform_device *pdev, struct emac_priv *priv)
 	np = pdev->dev.of_node;
 	pdata->version = EMAC_VERSION_2;
 
-	if (!is_valid_ether_addr(pdata->mac_addr)) {
-		mac_addr = of_get_mac_address(np);
-		if (!IS_ERR(mac_addr))
-			ether_addr_copy(pdata->mac_addr, mac_addr);
-	}
+	if (!is_valid_ether_addr(pdata->mac_addr))
+		of_get_mac_address(np, pdata->mac_addr);
 
 	of_property_read_u32(np, "ti,davinci-ctrl-reg-offset",
 			     &pdata->ctrl_reg_offset);
diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index d7a144b4a09f..9030e619e543 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -1966,7 +1966,6 @@ static int netcp_create_interface(struct netcp_device *netcp_device,
 	struct resource res;
 	void __iomem *efuse = NULL;
 	u32 efuse_mac = 0;
-	const void *mac_addr;
 	u8 efuse_mac_addr[6];
 	u32 temp[2];
 	int ret = 0;
@@ -2036,10 +2035,8 @@ static int netcp_create_interface(struct netcp_device *netcp_device,
 		devm_iounmap(dev, efuse);
 		devm_release_mem_region(dev, res.start, size);
 	} else {
-		mac_addr = of_get_mac_address(node_interface);
-		if (!IS_ERR(mac_addr))
-			ether_addr_copy(ndev->dev_addr, mac_addr);
-		else
+		ret = of_get_mac_address(node_interface, ndev->dev_addr);
+		if (ret)
 			eth_random_addr(ndev->dev_addr);
 	}