Re: [PATCH v2 2/3] net: add support for nvmem to eth_platform_get_mac_address()

From: Dan Carpenter
Date: Thu Jul 19 2018 - 08:39:02 EST


On Thu, Jul 19, 2018 at 12:06:51PM +0200, Bartosz Golaszewski wrote:
> It looks simpler as long as you don't add all the new routines
> resulting from this approach. I've just tried to quickly implement
> this solution and it resulted in much bigger and duplicated code
> (checking the validity of mac_addr, copying it etc.). I would prefer
> the current approach and would like to read someone else's opinion on
> that.

It's not too bad. There is two extra ether_addr_copy() calls and one
extra is_valid_ether_addr(). There are two extra alen declarations and
one extra addr declaration. The functions don't share *that* much code.

regards,
dan carpenter

diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index fd8faa0dfa61..8ab7289a5069 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -54,6 +54,8 @@
#include <linux/if_ether.h>
#include <linux/of_net.h>
#include <linux/pci.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/mtd/mtd.h>
#include <net/dst.h>
#include <net/arp.h>
#include <net/sock.h>
@@ -525,7 +527,7 @@ unsigned char * __weak arch_get_platform_mac_address(void)
return NULL;
}

-int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
+static int of_eth_get_mac_address(struct device *dev, u8 *mac_addr)
{
const unsigned char *addr;
struct device_node *dp;
@@ -547,4 +549,82 @@ int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
ether_addr_copy(mac_addr, addr);
return 0;
}
+
+static int nvmem_eth_get_mac_address(struct device *dev, u8 *mac_addr)
+{
+ struct nvmem_cell *nvmem;
+ unsigned char *addr;
+ size_t alen;
+ int ret = 0;
+
+ nvmem = nvmem_cell_get(dev, "mac-address");
+ if (PTR_ERR(nvmem) == -EPROBE_DEFER)
+ /* We may have a lookup registered for MAC address but the
+ * corresponding nvmem provider hasn't been registered yet.
+ */
+ return -EPROBE_DEFER;
+ if (IS_ERR(nvmem))
+ return PTR_ERR(nvmem);
+ addr = nvmem_cell_read(nvmem, &alen);
+ if (IS_ERR(addr)) {
+ ret = PTR_ERR(addr);
+ goto put_nvmem;
+ }
+ if (alen != ETH_ALEN || !is_valid_ether_addr(addr)) {
+ ret = -EINVAL;
+ goto free_addr;
+ }
+ ether_addr_copy(mac_addr, addr);
+free_addr:
+ kfree(addr);
+put_nvmem:
+ nvmem_cell_put(nvmem);
+ return ret;
+}
+
+static int mtd_eth_get_mac_address(struct device *dev, u8 *mac_addr)
+{
+ struct mtd_info *mtd;
+ u8 addrbuf[ETH_ALEN];
+ size_t alen;
+ int ret;
+
+ /* This function should go away as soon as MTD gets nvmem support. */
+ if (!IS_ENABLED(CONFIG_MTD))
+ return -ENODEV;
+
+ mtd = get_mtd_device_nm("MAC-Address");
+ if (IS_ERR(mtd))
+ return PTR_ERR(mtd);
+ ret = mtd_read(mtd, 0, ETH_ALEN, &alen, addrbuf);
+ if (ret)
+ goto put_mtd;
+ if (!is_valid_ether_addr(addrbuf)) {
+ ret = -EINVAL;
+ goto put_mtd;
+ }
+ ether_addr_copy(mac_addr, addrbuf);
+put_mtd:
+ put_mtd_device(mtd);
+ return ret;
+}
+
+int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
+{
+ int ret;
+
+ ret = of_eth_get_mac_address(dev, mac_addr);
+ if (!ret)
+ return 0;
+ ret = nvmem_eth_get_mac_address(dev, mac_addr);
+ if (ret == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ if (!ret)
+ return 0;
+ ret = mtd_eth_get_mac_address(dev, mac_addr);
+ if (!ret)
+ return 0;
+
+ return -ENODEV;
+}
EXPORT_SYMBOL(eth_platform_get_mac_address);