target/linux/generic/backport-5.4/771-mdio-bus-add-generic-find-bus.patch

   1 From ce69e2162f158d9d4a0e513971d02dabc7d14cb7 Mon Sep 17 00:00:00 2001
   2 From: Jeremy Linton <jeremy.linton@arm.com>
   3 Date: Mon, 24 Feb 2020 16:53:58 -0600
   4 Subject: [PATCH] mdio_bus: Add generic mdio_find_bus()
   5
   6 It appears most ethernet drivers follow one of two main strategies
   7 for mdio bus/phy management. A monolithic model where the net driver
   8 itself creates, probes and uses the phy, and one where an external
   9 mdio/phy driver instantiates the mdio bus/phy and the net driver
  10 only attaches to a known phy. Usually in this latter model the phys
  11 are discovered via DT relationships or simply phy name/address
  12 hardcoding.
  13
  14 This is a shame because modern well behaved mdio buses are self
  15 describing and can be probed. The mdio layer itself is fully capable
  16 of this, yet there isn't a clean way for a standalone net driver
  17 to attach and enumerate the discovered devices. This is because
  18 outside of of_mdio_find_bus() there isn't a straightforward way
  19 to acquire the mii_bus pointer.
  20
  21 So, lets add a mdio_find_bus which can return the mii_bus based
  22 only on its name.
  23
  24 Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
  25 Acked-by: Florian Fainelli <f.fainelli@gmail.com>
  26 Signed-off-by: David S. Miller <davem@davemloft.net>
  27 ---
  28  drivers/net/phy/mdio_bus.c | 17 +++++++++++++++++
  29  include/linux/phy.h        |  1 +
  30  2 files changed, 18 insertions(+)
  31
  32 --- a/drivers/net/phy/mdio_bus.c
  33 +++ b/drivers/net/phy/mdio_bus.c
  34 @@ -260,6 +260,23 @@ static struct class mdio_bus_class = {
  35         .dev_release    = mdiobus_release,
  36  };
  37
  38 +/**
  39 + * mdio_find_bus - Given the name of a mdiobus, find the mii_bus.
  40 + * @mdio_bus_np: Pointer to the mii_bus.
  41 + *
  42 + * Returns a reference to the mii_bus, or NULL if none found.  The
  43 + * embedded struct device will have its reference count incremented,
  44 + * and this must be put_deviced'ed once the bus is finished with.
  45 + */
  46 +struct mii_bus *mdio_find_bus(const char *mdio_name)
  47 +{
  48 +       struct device *d;
  49 +
  50 +       d = class_find_device_by_name(&mdio_bus_class, mdio_name);
  51 +       return d ? to_mii_bus(d) : NULL;
  52 +}
  53 +EXPORT_SYMBOL(mdio_find_bus);
  54 +
  55  #if IS_ENABLED(CONFIG_OF_MDIO)
  56  /**
  57   * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
  58 --- a/include/linux/phy.h
  59 +++ b/include/linux/phy.h
  60 @@ -273,6 +273,7 @@ static inline struct mii_bus *devm_mdiob
  61         return devm_mdiobus_alloc_size(dev, 0);
  62  }
  63
  64 +struct mii_bus *mdio_find_bus(const char *mdio_name);
  65  void devm_mdiobus_free(struct device *dev, struct mii_bus *bus);
  66  struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
  67