STRUCT MHI_CONTROLLER(9)

🦋 NAME 🦋

Okay bestie, welcome to the Kernel API Manual page for struct mhi_controller(9) — the Master MHI controller structure. This is the main-character struct of the MHI controller world, fr fr. 💅

✨ SYNOPSIS ✨

Here's the whole struct, copied exactly because we do not gatekeep 👑:

       struct mhi_controller {
           const char *name;
           struct device *cntrl_dev;
           struct mhi_device *mhi_dev;
           struct dentry *debugfs_dentry;
           void __iomem *regs;
           void __iomem *bhi;
           void __iomem *bhie;
           void __iomem *wake_db;
           dma_addr_t iova_start;
           dma_addr_t iova_stop;
           const char *fw_image;
           const u8 *fw_data;
           size_t fw_sz;
           const char *edl_image;
           size_t rddm_size;
           size_t sbl_size;
           size_t seg_len;
           size_t reg_len;
           struct image_info *fbc_image;
           struct image_info *rddm_image;
           struct mhi_chan *mhi_chan;
           struct list_head lpm_chans;
           int *irq;
           u32 max_chan;
           u32 total_ev_rings;
           u32 hw_ev_rings;
           u32 sw_ev_rings;
           u32 nr_irqs;
           u32 serial_number;
           struct mhi_event *mhi_event;
           struct mhi_cmd *mhi_cmd;
           struct mhi_ctxt *mhi_ctxt;
           struct mutex pm_mutex;
           rwlock_t pm_lock;
           u32 timeout_ms;
           u32 ready_timeout_ms;
           u32 pm_state;
           u32 db_access;
           enum mhi_ee_type ee;
           enum mhi_state dev_state;
           atomic_t dev_wake;
           atomic_t pending_pkts;
           u32 M0, M2, M3;
           struct list_head transition_list;
           spinlock_t transition_lock;
           spinlock_t wlock;
           struct mhi_link_info mhi_link_info;
           struct work_struct st_worker;
           struct workqueue_struct *hiprio_wq;
           wait_queue_head_t state_event;
           void (*status_cb)(struct mhi_controller *mhi_cntrl, enum
       mhi_callback cb);
           void (*wake_get)(struct mhi_controller *mhi_cntrl, bool override);
           void (*wake_put)(struct mhi_controller *mhi_cntrl, bool override);
           void (*wake_toggle)(struct mhi_controller *mhi_cntrl);
           int (*runtime_get)(struct mhi_controller *mhi_cntrl);
           void (*runtime_put)(struct mhi_controller *mhi_cntrl);
           int (*map_single)(struct mhi_controller *mhi_cntrl, struct
       mhi_buf_info *buf);
           void (*unmap_single)(struct mhi_controller *mhi_cntrl, struct
       mhi_buf_info *buf);
           int (*read_reg)(struct mhi_controller *mhi_cntrl, void __iomem
       *addr, u32 *out);
           void (*write_reg)(struct mhi_controller *mhi_cntrl, void __iomem
       *addr, u32 val);
           void (*reset)(struct mhi_controller *mhi_cntrl);
           int (*edl_trigger)(struct mhi_controller *mhi_cntrl);
           size_t buffer_len;
           int index;
           bool bounce_buf;
           bool fbc_download;
           bool wake_set;
           bool no_m3;
           unsigned long irq_flags;
           u32 mru;
        };

💅 Members 💅

Vibe check on every single field — required and optional tea included ☕✨:

• name — Device name of the MHI controller.
• cntrl_dev — Pointer to the struct device of physical bus acting as the MHI controller (required).
• mhi_dev — MHI device instance for the controller.
• debugfs_dentry — MHI controller debugfs directory.
• regs — Base address of MHI MMIO register space (required).
• bhi — Points to base of MHI BHI register space.
• bhie — Points to base of MHI BHIe register space.
• wake_db — MHI WAKE doorbell register address.
• iova_start — IOMMU starting address for data (required).
• iova_stop — IOMMU stop address for data (required).
• fw_image — Firmware image name for normal booting (optional).
• fw_data — Firmware image data content for normal booting, used only if fw_image is NULL and fbc_download is true (optional).
• fw_sz — Firmware image data size for normal booting, used only if fw_image is NULL and fbc_download is true (optional).
• edl_image — Firmware image name for emergency download mode (optional).
• rddm_size — RAM dump size that host should allocate for debugging purpose.
• sbl_size — SBL image size downloaded through BHIe (optional).
• seg_len — BHIe vector size (optional).
• reg_len — Length of the MHI MMIO region (required).
• fbc_image — Points to firmware image buffer.
• rddm_image — Points to RAM dump buffer.
• mhi_chan — Points to the channel configuration table.
• lpm_chans — List of channels that require LPM notifications.
• irq — base irq # to request (required).
• max_chan — Maximum number of channels the controller supports.
• total_ev_rings — Total # of event rings allocated.
• hw_ev_rings — Number of hardware event rings.
• sw_ev_rings — Number of software event rings.
• nr_irqs — Number of IRQ allocated by bus master (required).
• serial_number — MHI controller serial number obtained from BHI.
• mhi_event — MHI event ring configurations table.
• mhi_cmd — MHI command ring configurations table.
• mhi_ctxt — MHI device context, shared memory between host and device.
• pm_mutex — Mutex for suspend/resume operation.
• pm_lock — Lock for protecting MHI power management state.
• timeout_ms — Timeout in ms for state transitions.
• ready_timeout_ms — Timeout in ms for waiting device to be ready (optional).
• pm_state — MHI power management state.
• db_access — DB access states.
• ee — MHI device execution environment.
• dev_state — MHI device state.
• dev_wake — Device wakeup count.
• pending_pkts — Pending packets for the controller.
• M0 — Counter to track number of device MHI state changes.
• M2 — Counter to track number of device MHI state changes.
• M3 — Counter to track number of device MHI state changes.
• transition_list — List of MHI state transitions.
• transition_lock — Lock for protecting MHI state transition list.
• wlock — Lock for protecting device wakeup.
• mhi_link_info — Device bandwidth info.
• st_worker — State transition worker.
• hiprio_wq — High priority workqueue for MHI work such as state transitions.
• state_event — State change event.
• status_cb — CB function to notify power states of the device (required).
• wake_get — CB function to assert device wake (optional).
• wake_put — CB function to de-assert device wake (optional).
• wake_toggle — CB function to assert and de-assert device wake (optional).
• runtime_get — CB function to controller runtime resume (required).
• runtime_put — CB function to decrement pm usage (required).
• map_single — CB function to create TRE buffer.
• unmap_single — CB function to destroy TRE buffer.
• read_reg — Read a MHI register via the physical link (required).
• write_reg — Write a MHI register via the physical link (required).
• reset — Controller specific reset function (optional).
• edl_trigger — CB function to trigger EDL mode (optional).
• buffer_len — Bounce buffer length.
• index — Index of the MHI controller instance.
• bounce_buf — Use of bounce buffer.
• fbc_download — MHI host needs to do complete image transfer (optional).
• wake_set — Device wakeup set flag.
• no_m3 — Device doesn't support M3 state.
• irq_flags — irq flags passed to request_irq (optional).
• mru — the default MRU for the MHI device.

🎀 Description 🎀

Okay so here's the literal tea, bestie: fields marked as (required) need to be populated by the controller driver before calling mhi_register_controller. No cap, that's non-negotiable. For the fields marked as (optional), they can be populated depending on the usecase. That's the whole vibe. Slay. 💖

🔗 SEE ALSO 🔗

Kernel file ./include/linux/mhi.h — and the whole reference squad is:

• enum mhi_callback(9)
• enum mhi_flags(9)
• enum mhi_device_type(9)
• enum mhi_ch_type(9)
• struct mhi_buf(9)
• struct image_info(9)
• struct mhi_link_info(9)
• enum mhi_ee_type(9)
• enum mhi_state(9)
• enum mhi_ch_ee_mask(9)
• enum mhi_er_data_type(9)
• enum mhi_db_brst_mode(9)
• struct mhi_channel_config(9)
• struct mhi_event_config(9)
• struct mhi_controller_config(9)
• struct mhi_device(9)
• struct mhi_result(9)
• struct mhi_driver(9)
• mhi_alloc_controller(9)
• mhi_free_controller(9)
• mhi_register_controller(9)
• mhi_unregister_controller(9)
• __mhi_driver_register(9)
• mhi_driver_unregister(9)
• mhi_set_mhi_state(9)
• mhi_notify(9)
• mhi_get_free_desc_count(9)
• mhi_prepare_for_power_up(9)
• mhi_async_power_up(9)
• mhi_sync_power_up(9)
• mhi_power_down(9)
• mhi_power_down_keep_dev(9)
• mhi_unprepare_after_power_down(9)
• mhi_pm_suspend(9)
• mhi_pm_resume(9)
• mhi_pm_resume_force(9)
• mhi_download_rddm_image(9)
• mhi_force_rddm_mode(9)
• mhi_get_exec_env(9)
• mhi_get_mhi_state(9)
• mhi_soc_reset(9)
• mhi_device_get_sync(9)
• mhi_device_put(9)
• mhi_prepare_for_transfer(9)
• mhi_unprepare_from_transfer(9)
• mhi_queue_buf(9)
• mhi_queue_skb(9)
• mhi_queue_is_full(9)
• mhi_get_channel_doorbell_offset(9)

💌 Cute sign-off: this page ships from ./include/linux, dated October 2026, and yes it's struct mhi_controller(9). Byeee — go populate those required fields 💅✨🫶