STRUCT MII_BUS(9)

📦 version 7.3.1, in nixpkgs unstable

✨ struct mii_bus(9) ✨

okay so bestie, we're in the struct mii_bus(9) page — the Kernel API Manual entry — and it's literally the blueprint for an MDIO bus. no cap, this is the glow-up doc for the thing that talks to your PHYs. let's get into it 💅

🌸 NAME 🌸

struct mii_bus — Represents an MDIO bus 🦋

🎀 SYNOPSIS 🎀

like, here's the whole struct, every single field, in order, don't touch:

struct mii_bus {
    struct module *owner;
    const char *name;
    char id[MII_BUS_ID_SIZE];
    void *priv;
    int (*read)(struct mii_bus *bus, int addr, int regnum);
    int (*write)(struct mii_bus *bus, int addr, int regnum, u16 val);
    int (*read_c45)(struct mii_bus *bus, int addr, int devnum, int regnum);
    int (*write_c45)(struct mii_bus *bus, int addr, int devnum, int regnum, u16 val);
    int (*reset)(struct mii_bus *bus);
    struct mdio_bus_stats stats[PHY_MAX_ADDR];
    struct mutex mdio_lock;
    struct device *parent;
    enum {
      MDIOBUS_ALLOCATED = 1,
      MDIOBUS_REGISTERED,
      MDIOBUS_UNREGISTERED,
      MDIOBUS_RELEASED,
    } state;
    struct device dev;
    struct mdio_device *mdio_map[PHY_MAX_ADDR];
    u32 phy_mask;
    u32 phy_ignore_ta_mask;
    int irq[PHY_MAX_ADDR];
    int reset_delay_us;
    int reset_post_delay_us;
    struct gpio_desc *reset_gpiod;
    struct mutex shared_lock;
  #if IS_ENABLED(CONFIG_PHY_PACKAGE);
    struct phy_package_shared *shared[PHY_MAX_ADDR];
  #endif;
 };

🫶 Members 🫶

every field gets its moment, bestie, no skipping:

  • owner — who owns this device 👑
  • name — user friendly name for this MDIO device, or the driver name
  • id — unique identifier for this bus, typically from bus hierarchy
  • priv — driver private data 🙈
  • read — perform a read transfer on the bus
  • write — perform a write transfer on the bus
  • read_c45 — perform a C45 read transfer on the bus
  • write_c45 — perform a C45 write transfer on the bus
  • reset — perform a reset of the bus 🔥
  • stats — statistic counters per device on the bus
  • mdio_lock — a lock to ensure that only one thing can read/write the MDIO bus at a time
  • parent — parent device of this bus
  • state — state of bus structure
  • dev — kernel device representation
  • mdio_map — list of all MDIO devices on bus
  • phy_mask — PHY addresses to be ignored when probing
  • phy_ignore_ta_mask — PHY addresses to ignore the TA/read failure
  • irq — an array of interrupts, each PHY's interrupt at the index matching its address
  • reset_delay_us — GPIO reset pulse width in microseconds
  • reset_post_delay_us — GPIO reset deassert delay in microseconds
  • reset_gpiod — Reset GPIO descriptor pointer
  • shared_lock — protect access to the shared element
  • shared — shared state across different PHYs

💖 Description 💖

the Bus class for PHYs, periodt. devices which provide access to PHYs should register using this structure ✨

🌈 SEE ALSO 🌈

kernel file ./include/linux/phy.h — and yes, the whole friend group is here 💀

and that's the whole thing, bestie 🎀 this page lives in ./include/linux and it's dated October 2026 — so like, future vibes, iconic. go read your PHY headers, mwah 💖👑

📦 where this page comes from