STRUCT CONTROLLER(9)

💖 struct controller(9) — PCIe hotplug controller 💖

okay so bestie, welcome to the Kernel API Manual page for struct controller. It’s the PCIe hotplug controller, and yes, it’s giving main character energy. ✨

🌸 NAME 🌸

struct controller — PCIe hotplug controller 🎀

🦋 SYNOPSIS 🦋

       struct controller {
           struct pcie_device *pcie;
           u64 dsn;
           u32 slot_cap;
           unsigned int inband_presence_disabled:1;
           u16 slot_ctrl;
           struct mutex ctrl_lock;
           unsigned long cmd_started;
           unsigned int cmd_busy:1;
           wait_queue_head_t queue;
           atomic_t pending_events;
           unsigned int notification_enabled:1;
           unsigned int power_fault_detected;
           struct task_struct *poll_thread;
           u8 state;
           struct mutex state_lock;
           struct delayed_work button_work;
           struct hotplug_slot hotplug_slot;
           struct rw_semaphore reset_lock;
           unsigned int depth;
           unsigned int ist_running;
           int request_result;
           wait_queue_head_t requester;
        };

🎀 Members 🎀

• pcie — pointer to the controller’s PCIe port service device. 💅
• dsn — cached copy of the Device Serial Number of Function 0 in the hotplug slot (PCIe r6.2 sec 7.9.3); it’s used to determine whether a hotplugged device was replaced with a different one during system sleep.
• slot_cap — cached copy of the Slot Capabilities register.
• inband_presence_disabled — In-Band Presence Detect Disable supported by the controller and disabled per the spec recommendation (PCIe r5.0, appendix I implementation note).
• slot_ctrl — cached copy of the Slot Control register.
• ctrl_lock — serializes writes to the Slot Control register.
• cmd_started — jiffies when the Slot Control register was last written; the next write is allowed 1 second later, absent a Command Completed interrupt (PCIe r4.0, sec 6.7.3.2).
• cmd_busy — flag set on Slot Control register write, cleared by the IRQ handler on reception of a Command Completed event.
• queue — wait queue to wake up on reception of a Command Completed event, used for synchronous writes to the Slot Control register.
• pending_events — used by the IRQ handler to save events retrieved from the Slot Status register for later consumption by the IRQ thread.
• notification_enabled — whether the IRQ was requested successfully.
• power_fault_detected — whether a power fault was detected by the hardware that has not yet been cleared by the user.
• poll_thread — thread to poll for slot events if no IRQ is available, enabled with the pciehp_poll_mode module parameter.
• state — current state machine position.
• state_lock — protects reads and writes of state; protects scheduling, execution and cancellation of button_work.
• button_work — work item to turn the slot on or off after 5 seconds in response to an Attention Button press.
• hotplug_slot — structure registered with the PCI hotplug core.
• reset_lock — prevents access to the Data Link Layer Link Active bit in the Link Status register and to the Presence Detect State bit in the Slot Status register during a slot reset which may cause them to flap.
• depth — Number of additional hotplug ports in the path to the root bus, used as lock subclass for reset_lock.
• ist_running — flag to keep user request waiting while the IRQ thread is running.
• request_result — result of last user request submitted to the IRQ thread.
• requester — wait queue to wake up on completion of user request, used for synchronous slot enable/disable request via sysfs.

🌸 Description 🌸

PCIe hotplug has a 1:1 relationship between controller and slot, hence unlike other drivers, the two aren’t represented by separate structures. slay, simplicity. 💖

🌈 SEE ALSO 🌈

• Kernel file ./drivers/pci/hotplug/pciehp.h
• Slot state(9)
• Flags to request an action from the IRQ thread(9)

mwah 💋 this cutie comes from ./drivers/pci/hotplug, dated October 2026. source/version + date sign-off complete, bestie. 🫶💜