[PATCH net-next v3 2/2] of: net: fix of_get_mac_addr_nvmem() for PCI and DSA nodes

[Michael Walle <michael@walle.cc>]

of_get_mac_address() already supports fetching the MAC address by an
nvmem provider. But until now, it was just working for platform devices.
Esp. it was not working for DSA ports and PCI devices. It gets more
common that PCI devices have a device tree binding since SoCs contain
integrated root complexes.

Use the nvmem of_* binding to fetch the nvmem cells by a struct
device_node. We still have to try to read the cell by device first
because there might be a nvmem_cell_lookup associated with that device.

Signed-off-by: Michael Walle <michael@walle.cc>
---
Please note, that I've kept the nvmem_get_mac_address() which operates
on a device. The new of_get_mac_addr_nvmem() is almost identical and
there are no users of the former function right now, but it seems to be
the "newer" version to get the MAC address for a "struct device". Thus
I've kept it. Please advise, if I should kill it though.

 drivers/of/of_net.c | 35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c
index 2d5d5e59aea5..2323c6063eaf 100644
--- a/drivers/of/of_net.c
+++ b/drivers/of/of_net.c
@@ -11,6 +11,7 @@
 #include <linux/phy.h>
 #include <linux/export.h>
 #include <linux/device.h>
+#include <linux/nvmem-consumer.h>
 
 /**
  * of_get_phy_mode - Get phy mode for given device_node
@@ -59,15 +60,39 @@ static int of_get_mac_addr(struct device_node *np, const char *name, u8 *addr)
 static int of_get_mac_addr_nvmem(struct device_node *np, u8 *addr)
 {
 	struct platform_device *pdev = of_find_device_by_node(np);
+	struct nvmem_cell *cell;
+	const void *mac;
+	size_t len;
 	int ret;
 
-	if (!pdev)
-		return -ENODEV;
+	/* Try lookup by device first, there might be a nvmem_cell_lookup
+	 * associated with a given device.
+	 */
+	if (pdev) {
+		ret = nvmem_get_mac_address(&pdev->dev, addr);
+		put_device(&pdev->dev);
+		return ret;
+	}
+
+	cell = of_nvmem_cell_get(np, "mac-address");
+	if (IS_ERR(cell))
+		return PTR_ERR(cell);
+
+	mac = nvmem_cell_read(cell, &len);
+	nvmem_cell_put(cell);
+
+	if (IS_ERR(mac))
+		return PTR_ERR(mac);
+
+	if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
+		kfree(mac);
+		return -EINVAL;
+	}
 
-	ret = nvmem_get_mac_address(&pdev->dev, addr);
-	put_device(&pdev->dev);
+	ether_addr_copy(addr, mac);
+	kfree(mac);
 
-	return ret;
+	return 0;
 }
 
 /**
-- 
2.20.1