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net: export device speed and duplex via sysfs
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This patch exports the link-speed (in Mbps) and duplex of an interface
via sysfs.  This eliminates the need to use ethtool just to check the
link-speed.  Not requiring 'ethtool' and not relying on the SIOCETHTOOL
ioctl should be helpful in an embedded environment where space is at a
premium as well.

NOTE: This patch also intentionally allows non-root users to check the link
speed and duplex -- something not possible with ethtool.

Here's some sample output:

# cat /sys/class/net/eth0/speed
100
# cat /sys/class/net/eth0/duplex
half
# ethtool eth0
Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  Not reported
        Advertised auto-negotiation: No
        Speed: 100Mb/s
        Duplex: Half
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x000000ff (255)
        Link detected: yes

Signed-off-by: David S. Miller <davem@davemloft.net>
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gospo authored and davem330 committed Oct 5, 2009
1 parent 053a93d commit d519e17
Showing 1 changed file with 40 additions and 0 deletions.
40 changes: 40 additions & 0 deletions net/core/net-sysfs.c
Original file line number Diff line number Diff line change
Expand Up @@ -130,6 +130,44 @@ static ssize_t show_carrier(struct device *dev,
return -EINVAL;
}

static ssize_t show_speed(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct net_device *netdev = to_net_dev(dev);
int ret = -EINVAL;

if (!rtnl_trylock())
return restart_syscall();

if (netif_running(netdev) && netdev->ethtool_ops->get_settings) {
struct ethtool_cmd cmd = { ETHTOOL_GSET };

if (!netdev->ethtool_ops->get_settings(netdev, &cmd))
ret = sprintf(buf, fmt_dec, ethtool_cmd_speed(&cmd));
}
rtnl_unlock();
return ret;
}

static ssize_t show_duplex(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct net_device *netdev = to_net_dev(dev);
int ret = -EINVAL;

if (!rtnl_trylock())
return restart_syscall();

if (netif_running(netdev) && netdev->ethtool_ops->get_settings) {
struct ethtool_cmd cmd = { ETHTOOL_GSET };

if (!netdev->ethtool_ops->get_settings(netdev, &cmd))
ret = sprintf(buf, "%s\n", cmd.duplex ? "full" : "half");
}
rtnl_unlock();
return ret;
}

static ssize_t show_dormant(struct device *dev,
struct device_attribute *attr, char *buf)
{
Expand Down Expand Up @@ -259,6 +297,8 @@ static struct device_attribute net_class_attributes[] = {
__ATTR(address, S_IRUGO, show_address, NULL),
__ATTR(broadcast, S_IRUGO, show_broadcast, NULL),
__ATTR(carrier, S_IRUGO, show_carrier, NULL),
__ATTR(speed, S_IRUGO, show_speed, NULL),
__ATTR(duplex, S_IRUGO, show_duplex, NULL),
__ATTR(dormant, S_IRUGO, show_dormant, NULL),
__ATTR(operstate, S_IRUGO, show_operstate, NULL),
__ATTR(mtu, S_IRUGO | S_IWUSR, show_mtu, store_mtu),
Expand Down

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