It appears most ethernet drivers follow one of two main strategies
for mdio bus/phy management. A monolithic model where the net driver
itself creates, probes and uses the phy, and one where an external
mdio/phy driver instantiates the mdio bus/phy and the net driver
only attaches to a known phy. Usually in this latter model the phys
are discovered via DT relationships or simply phy name/address
hardcoding.
This is a shame because modern well behaved mdio buses are self
describing and can be probed. The mdio layer itself is fully capable
of this, yet there isn't a clean way for a standalone net driver
to attach and enumerate the discovered devices. This is because
outside of of_mdio_find_bus() there isn't a straightforward way
to acquire the mii_bus pointer.
So, lets add a mdio_find_bus which can return the mii_bus based
only on its name.
Signed-off-by: Jeremy Linton <[email protected]>
---
drivers/net/phy/mdio_bus.c | 17 +++++++++++++++++
include/linux/phy.h | 1 +
2 files changed, 18 insertions(+)
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 9bb9f37f21dc..3ab9ca7614d1 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -462,6 +462,23 @@ static struct class mdio_bus_class = {
.dev_groups = mdio_bus_groups,
};
+/**
+ * mdio_find_bus - Given the name of a mdiobus, find the mii_bus.
+ * @mdio_bus_np: Pointer to the mii_bus.
+ *
+ * Returns a reference to the mii_bus, or NULL if none found. The
+ * embedded struct device will have its reference count incremented,
+ * and this must be put_deviced'ed once the bus is finished with.
+ */
+struct mii_bus *mdio_find_bus(const char *mdio_name)
+{
+ struct device *d;
+
+ d = class_find_device_by_name(&mdio_bus_class, mdio_name);
+ return d ? to_mii_bus(d) : NULL;
+}
+EXPORT_SYMBOL(mdio_find_bus);
+
#if IS_ENABLED(CONFIG_OF_MDIO)
/**
* of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
diff --git a/include/linux/phy.h b/include/linux/phy.h
index c570e162e05e..bd4ac49a9dbe 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -289,6 +289,7 @@ static inline struct mii_bus *devm_mdiobus_alloc(struct device *dev)
return devm_mdiobus_alloc_size(dev, 0);
}
+struct mii_bus *mdio_find_bus(const char *mdio_name);
void devm_mdiobus_free(struct device *dev, struct mii_bus *bus);
struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
--
2.24.1
On 2/24/20 2:53 PM, Jeremy Linton wrote:
> It appears most ethernet drivers follow one of two main strategies
> for mdio bus/phy management. A monolithic model where the net driver
> itself creates, probes and uses the phy, and one where an external
> mdio/phy driver instantiates the mdio bus/phy and the net driver
> only attaches to a known phy. Usually in this latter model the phys
> are discovered via DT relationships or simply phy name/address
> hardcoding.
>
> This is a shame because modern well behaved mdio buses are self
> describing and can be probed. The mdio layer itself is fully capable
> of this, yet there isn't a clean way for a standalone net driver
> to attach and enumerate the discovered devices. This is because
> outside of of_mdio_find_bus() there isn't a straightforward way
> to acquire the mii_bus pointer.
>
> So, lets add a mdio_find_bus which can return the mii_bus based
> only on its name.
>
> Signed-off-by: Jeremy Linton <[email protected]>
Acked-by: Florian Fainelli <[email protected]>
--
Florian