hw/net/imx_fec: Support two Ethernet interfaces connected to single MDIO bus

The SOC on i.MX6UL and i.MX7 has 2 Ethernet interfaces. The PHY on each may
be connected to separate MDIO busses, or both may be connected on the same
MDIO bus using different PHY addresses. Commit 461c51ad4275 ("Add a phy-num
property to the i.MX FEC emulator") added support for specifying PHY
addresses, but it did not provide support for linking the second PHY on
a given MDIO bus to the other Ethernet interface.

To be able to support two PHY instances on a single MDIO bus, two properties
are needed: First, there needs to be a flag indicating if the MDIO bus on
a given Ethernet interface is connected. If not, attempts to read from this
bus must always return 0xffff. Implement this property as phy-connected.
Second, if the MDIO bus on an interface is active, it needs a link to the
consumer interface to be able to provide PHY access for it. Implement this
property as phy-consumer.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 20230315145248.1639364-2-linux@roeck-us.net
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/hw/net/imx_fec.h b/include/hw/net/imx_fec.h
index e3a8755..2d13290 100644
--- a/include/hw/net/imx_fec.h
+++ b/include/hw/net/imx_fec.h
@@ -270,6 +270,8 @@ struct IMXFECState {
     uint32_t phy_int;
     uint32_t phy_int_mask;
     uint32_t phy_num;
+    bool phy_connected;
+    struct IMXFECState *phy_consumer;
 
     bool is_fec;