STRUCT MHI_EP_CNTRL(9)

🌸 struct mhi_ep_cntrl(9) 🌸

okay so bestie, we're in the Kernel API Manual and this page is all about struct mhi_ep_cntrl — literally the MHI Endpoint controller structure. it's the big main-character struct that holds everything the endpoint side needs. no cap, it's a long one, but we're gonna walk through every single field together, hand in hand 🫶

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✨ SYNOPSIS ✨

like, here's the whole vibe of the struct, every field, exactly as it is — don't touch, just read 💅

struct mhi_ep_cntrl {
    struct device *cntrl_dev;
    struct mhi_ep_device *mhi_dev;
    void __iomem *mmio;
    struct mhi_ep_chan *mhi_chan;
    struct mhi_ep_event *mhi_event;
    struct mhi_ep_cmd *mhi_cmd;
    struct mhi_ep_sm *sm;
    struct mhi_chan_ctxt *ch_ctx_cache;
    struct mhi_event_ctxt *ev_ctx_cache;
    struct mhi_cmd_ctxt *cmd_ctx_cache;
    u64 ch_ctx_host_pa;
    u64 ev_ctx_host_pa;
    u64 cmd_ctx_host_pa;
    phys_addr_t ch_ctx_cache_phys;
    phys_addr_t ev_ctx_cache_phys;
    phys_addr_t cmd_ctx_cache_phys;
    struct mhi_ep_db_info chdb[4];
    struct mutex event_lock;
    struct mutex state_lock;
    spinlock_t list_lock;
    struct list_head st_transition_list;
    struct list_head ch_db_list;
    struct workqueue_struct *wq;
    struct work_struct state_work;
    struct work_struct reset_work;
    struct work_struct cmd_ring_work;
    struct work_struct ch_ring_work;
    struct kmem_cache *ring_item_cache;
    struct kmem_cache *ev_ring_el_cache;
    struct kmem_cache *tre_buf_cache;
    void (*raise_irq)(struct mhi_ep_cntrl *mhi_cntrl, u32 vector);
    int (*alloc_map)(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
phys_addr_t *phys_ptr, void __iomem **virt, size_t size);
    void (*unmap_free)(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
phys_addr_t phys, void __iomem *virt, size_t size);
    int (*read_sync)(struct mhi_ep_cntrl *mhi_cntrl, struct
mhi_ep_buf_info *buf_info);
    int (*write_sync)(struct mhi_ep_cntrl *mhi_cntrl, struct
mhi_ep_buf_info *buf_info);
    int (*read_async)(struct mhi_ep_cntrl *mhi_cntrl, struct
mhi_ep_buf_info *buf_info);
    int (*write_async)(struct mhi_ep_cntrl *mhi_cntrl, struct
mhi_ep_buf_info *buf_info);
    void (*flush_async)(struct mhi_ep_cntrl *mhi_cntrl);
    enum mhi_state mhi_state;
    u32 max_chan;
    u32 mru;
    u32 event_rings;
    u32 hw_event_rings;
    u32 chdb_offset;
    u32 erdb_offset;
    u32 index;
    int irq;
    bool enabled;
 };

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🎀 Members 🎀

💖 the pointers & basics

• cntrl_dev — pointer to the struct device of the physical bus that's acting as the MHI Endpoint controller. like, the actual device it lives on 🦋
• mhi_dev — the MHI Endpoint device instance for this controller
• mmio — the MMIO region that contains the MHI registers
• mhi_chan — points to the channel configuration table
• mhi_event — points to the event ring configurations table
• mhi_cmd — points to the command ring configurations table
• sm — the MHI Endpoint state machine (yes, she has a whole state machine, queen behavior 👑)

🧚 the host context caches

• ch_ctx_cache — cache of the host channel context data structure
• ev_ctx_cache — cache of the host event context data structure
• cmd_ctx_cache — cache of the host command context data structure

⭐ the host context physical addresses

• ch_ctx_host_pa — physical address of the host channel context data structure
• ev_ctx_host_pa — physical address of the host event context data structure
• cmd_ctx_host_pa — physical address of the host command context data structure

🌸 the cache physical addresses

• ch_ctx_cache_phys — physical address of the host channel context cache
• ev_ctx_cache_phys — physical address of the host event context cache
• cmd_ctx_cache_phys — physical address of the host command context cache

🔥 doorbells, locks & lists

• chdb — array of channel doorbell interrupt info
• event_lock — the lock protecting event rings
• state_lock — the lock protecting state transitions
• list_lock — the lock protecting the state transition and channel doorbell lists
• st_transition_list — list of state transitions
• ch_db_list — list of queued channel doorbells

🫶 the workqueue situation

• wq — a dedicated workqueue for handling rings and state changes
• state_work — the state transition worker
• reset_work — the worker for MHI Endpoint reset
• cmd_ring_work — the worker for processing command rings
• ch_ring_work — the worker for processing channel rings

🍓 the callbacks (iykyk)

• raise_irq — CB function for raising an IRQ to the host
• alloc_map — CB function for allocating memory in the endpoint for storing host context and mapping it
• unmap_free — CB function to unmap and free the allocated memory in the endpoint for storing host context
• read_sync — CB function for reading from host memory synchronously
• write_sync — CB function for writing to host memory synchronously
• read_async — CB function for reading from host memory asynchronously
• write_async — CB function for writing to host memory asynchronously
• flush_async — CB function for flushing asynchronous read/writes

🌈 the config & state bits

• mhi_state — the MHI Endpoint state
• max_chan — maximum channels supported by the endpoint controller
• mru — the MRU (Maximum Receive Unit) value of the endpoint controller
• event_rings — number of event rings supported by the endpoint controller
• hw_event_rings — number of hardware event rings supported by the endpoint controller
• chdb_offset — channel doorbell offset set by the host
• erdb_offset — event ring doorbell offset set by the host
• index — the MHI Endpoint controller index
• irq — the IRQ used by the endpoint controller
• enabled — check if the endpoint controller is enabled or not

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👑 SEE ALSO 👑

go read these next bestie, they're all in the kernel file ./include/linux/mhi_ep.h:

• struct mhi_ep_channel_config(9)
• struct mhi_ep_cntrl_config(9)
• struct mhi_ep_db_info(9)
• struct mhi_ep_buf_info(9)
• struct mhi_ep_device(9)
• struct mhi_ep_driver(9)
• __mhi_ep_driver_register(9)
• mhi_ep_driver_unregister(9)
• mhi_ep_register_controller(9)
• mhi_ep_unregister_controller(9)
• mhi_ep_power_up(9)
• mhi_ep_power_down(9)
• mhi_ep_queue_is_empty(9)
• mhi_ep_queue_skb(9)

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💀 reminder bestie: this page lives in ./include/linux and it's dated October 2026 — that's the Linux kernel source tree, so check the actual header before you go shipping anything, fr fr.

okay that's the whole struct, you ate that 💅✨ go be iconic with your endpoint controller 🎀🦋💜