Commit 3be2a49e authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by David S. Miller
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of: provide a binding for fixed link PHYs

Some Ethernet MACs have a "fixed link", and are not connected to a
normal MDIO-managed PHY device. For those situations, a Device Tree
binding allows to describe a "fixed link" using a special PHY node.

This patch adds:

 * A documentation for the fixed PHY Device Tree binding.

 * An of_phy_is_fixed_link() function that an Ethernet driver can call
   on its PHY phandle to find out whether it's a fixed link PHY or
   not. It should typically be used to know if
   of_phy_register_fixed_link() should be called.

 * An of_phy_register_fixed_link() function that instantiates the
   fixed PHY into the PHY subsystem, so that when the driver calls
   of_phy_connect(), the PHY device associated to the OF node will be

These two additional functions also support the old fixed-link Device
Tree binding used on PowerPC platforms, so that ultimately, the
network device drivers for those platforms could be converted to use
of_phy_is_fixed_link() and of_phy_register_fixed_link() instead of
of_phy_connect_fixed_link(), while keeping compatibility with their
respective Device Tree bindings.
Signed-off-by: default avatarThomas Petazzoni <>
Reviewed-by: default avatarFlorian Fainelli <>
Tested-by: default avatarFlorian Fainelli <>
Signed-off-by: default avatarDavid S. Miller <>
parent a7595121
Fixed link Device Tree binding
Some Ethernet MACs have a "fixed link", and are not connected to a
normal MDIO-managed PHY device. For those situations, a Device Tree
binding allows to describe a "fixed link".
Such a fixed link situation is described by creating a 'fixed-link'
sub-node of the Ethernet MAC device node, with the following
* 'speed' (integer, mandatory), to indicate the link speed. Accepted
values are 10, 100 and 1000
* 'full-duplex' (boolean, optional), to indicate that full duplex is
used. When absent, half duplex is assumed.
* 'pause' (boolean, optional), to indicate that pause should be
* 'asym-pause' (boolean, optional), to indicate that asym_pause should
be enabled.
ethernet@0 {
fixed-link {
speed = <1000>;
......@@ -14,6 +14,7 @@
#include <linux/netdevice.h>
#include <linux/err.h>
#include <linux/phy.h>
#include <linux/phy_fixed.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_mdio.h>
......@@ -301,3 +302,69 @@ struct phy_device *of_phy_attach(struct net_device *dev,
return phy_attach_direct(dev, phy, flags, iface) ? NULL : phy;
#if defined(CONFIG_FIXED_PHY)
* of_phy_is_fixed_link() and of_phy_register_fixed_link() must
* support two DT bindings:
* - the old DT binding, where 'fixed-link' was a property with 5
* cells encoding various informations about the fixed PHY
* - the new DT binding, where 'fixed-link' is a sub-node of the
* Ethernet device.
bool of_phy_is_fixed_link(struct device_node *np)
struct device_node *dn;
int len;
/* New binding */
dn = of_get_child_by_name(np, "fixed-link");
if (dn) {
return true;
/* Old binding */
if (of_get_property(np, "fixed-link", &len) &&
len == (5 * sizeof(__be32)))
return true;
return false;
int of_phy_register_fixed_link(struct device_node *np)
struct fixed_phy_status status = {};
struct device_node *fixed_link_node;
const __be32 *fixed_link_prop;
int len;
/* New binding */
fixed_link_node = of_get_child_by_name(np, "fixed-link");
if (fixed_link_node) { = 1;
status.duplex = of_property_read_bool(np, "full-duplex");
if (of_property_read_u32(fixed_link_node, "speed", &status.speed))
return -EINVAL;
status.pause = of_property_read_bool(np, "pause");
status.asym_pause = of_property_read_bool(np, "asym-pause");
return fixed_phy_register(PHY_POLL, &status, np);
/* Old binding */
fixed_link_prop = of_get_property(np, "fixed-link", &len);
if (fixed_link_prop && len == (5 * sizeof(__be32))) { = 1;
status.duplex = be32_to_cpu(fixed_link_prop[1]);
status.speed = be32_to_cpu(fixed_link_prop[2]);
status.pause = be32_to_cpu(fixed_link_prop[3]);
status.asym_pause = be32_to_cpu(fixed_link_prop[4]);
return fixed_phy_register(PHY_POLL, &status, np);
return -ENODEV;
......@@ -72,4 +72,19 @@ static inline struct mii_bus *of_mdio_find_bus(struct device_node *mdio_np)
#endif /* CONFIG_OF */
#if defined(CONFIG_OF) && defined(CONFIG_FIXED_PHY)
extern int of_phy_register_fixed_link(struct device_node *np);
extern bool of_phy_is_fixed_link(struct device_node *np);
static inline int of_phy_register_fixed_link(struct device_node *np)
return -ENOSYS;
static inline bool of_phy_is_fixed_link(struct device_node *np)
return false;
#endif /* __LINUX_OF_MDIO_H */
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