net: phy: introduce fixed_phy_create for DSA CPU ports
The DSA (Distributed Switch Architecture) implementation has made a
design decision when it got introduced to the Linux kernel in 2008.
That was to hide away from the user the CPU-facing Ethernet MAC, since
it does not make sense to register it as a struct net_device (UCLASS_ETH
udevice for U-Boot), because that would never be beneficial for a user:
they would not be able to use it for traffic, since conceptually, a
packet delivered to the CPU port should loop back into the system.
Nonetheless, DSA has had numerous growing pains due to the lack of a
struct net_device for the CPU port, but so far it has overcome them.
It is unlikely at this stage of maturity that this aspect of it will
change.
We would like U-Boot to present the same information as Linux, to be at
parity in terms of number of interfaces, so that ethNaddr environment
variables could directly be associated between U-Boot and Linux.
Therefore, we would implicitly like U-Boot to hide the CPU port from the
user as well.
But the paradox is that DSA still needs a struct phy_device to inform
the driver of the parameters of the link that it should configure the
CPU port to. The problem is that the phy_device is typically returned
via a call to phy_connect, which needs an udevice to attach the PHY to,
and to search its ofnode for the 'fixed-link' property. But we don't
have an udevice to present for the CPU port.
Since 99% of DSA setups are MAC-to-MAC connections between the switch
and the host Ethernet controller, the struct phy_device is going to be a
fixed PHY. This simplifies things quite a bit. In U-Boot, a fixed PHY
does not need an MDIO bus, and does not need an attached dev either.
Basically, the phy_connect call doesn't do any connection, it just
creates the fixed PHY.
The proposal of this patch is to introduce a new fixed_phy_create
function which will take a single argument: the ofnode that holds this:
port@4 {
reg = <4>;
phy-mode = "internal";
fixed-link {
speed = <2500>;
full-duplex;
};
};
and probe a fixed PHY driver using the information from this ofnode.
DSA will probably be the only user of this function.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index a2be398..89e3076 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -977,6 +977,37 @@
#endif
#ifdef CONFIG_PHY_FIXED
+/**
+ * fixed_phy_create() - create an unconnected fixed-link pseudo-PHY device
+ * @node: OF node for the container of the fixed-link node
+ *
+ * Description: Creates a struct phy_device based on a fixed-link of_node
+ * description. Can be used without phy_connect by drivers which do not expose
+ * a UCLASS_ETH udevice.
+ */
+struct phy_device *fixed_phy_create(ofnode node)
+{
+ phy_interface_t interface = PHY_INTERFACE_MODE_NONE;
+ const char *if_str;
+ ofnode subnode;
+
+ if_str = ofnode_read_string(node, "phy-mode");
+ if (!if_str) {
+ if_str = ofnode_read_string(node, "phy-interface-type");
+ }
+ if (if_str) {
+ interface = phy_get_interface_by_name(if_str);
+ }
+
+ subnode = ofnode_find_subnode(node, "fixed-link");
+ if (!ofnode_valid(subnode)) {
+ return NULL;
+ }
+
+ return phy_device_create(NULL, ofnode_to_offset(subnode), PHY_FIXED_ID,
+ false, interface);
+}
+
#ifdef CONFIG_DM_ETH
static struct phy_device *phy_connect_fixed(struct mii_dev *bus,
struct udevice *dev,