STRUCT DW_MCI(9)

💖 struct dw_mci(9) — Kernel API Manual 💖

✨ NAME ✨

struct dw_mci — MMC controller state. That's the whole vibe, bestie. 💅

🦋 SYNOPSIS 🦋

       struct dw_mci {
           spinlock_t lock;
           spinlock_t irq_lock;
           void __iomem            *regs;
           void __iomem            *fifo_reg;
           u32 data_addr_override;
           u32 dma_threshold;
           bool wm_aligned;
           struct scatterlist      *sg;
           struct sg_mapping_iter  sg_miter;
           struct mmc_request      *mrq;
           struct mmc_command      *cmd;
           struct mmc_data         *data;
           struct mmc_command      stop_abort;
           unsigned int            prev_blksz;
           unsigned char           timing;
           int use_dma;
           int using_dma;
           int dma_64bit_address;
           dma_addr_t sg_dma;
           void *sg_cpu;
           const struct dw_mci_dma_ops     *dma_ops;
           unsigned short          desc_num;
           struct dw_mci_dma_slave *dms;
           resource_size_t phy_regs;
           u32 cmd_status;
           u32 data_status;
           u32 stop_cmdr;
           u32 dir_status;
           struct work_struct      bh_work;
           unsigned long           pending_events;
           unsigned long           completed_events;
           enum dw_mci_state       state;
           u32 bus_hz;
           u32 current_speed;
           u32 minimum_speed;
           u32 fifoth_val;
           u16 verid;
           struct device           *dev;
           const struct dw_mci_drv_data    *drv_data;
           void *priv;
           struct clk              *biu_clk;
           struct clk              *ciu_clk;
           struct dw_mci_slot      *slot;
           int fifo_depth;
           int data_shift;
           u8 part_buf_start;
           u8 part_buf_count;
           union {
             u16 part_buf16;
             u32 part_buf32;
             u64 part_buf;
           };
           void (*push_data)(struct dw_mci *host, void *buf, int cnt);
           void (*pull_data)(struct dw_mci *host, void *buf, int cnt);
           u32 quirks;
           unsigned long           irq_flags;
           int irq;
           int sdio_irq;
           struct timer_list       cmd11_timer;
           struct timer_list       cto_timer;
           struct timer_list       dto_timer;
         #ifdef CONFIG_FAULT_INJECTION;
           struct fault_attr       fail_data_crc;
           struct hrtimer          fault_timer;
         #endif;
           struct mmc_host         *mmc;
           unsigned long           flags;
         #define DW_MMC_CARD_NEED_INIT   0;
         #define DW_MMC_CARD_NO_LOW_PWR  1;
         #define DW_MMC_CARD_NO_USE_HOLD 2;
         #define DW_MMC_CARD_NEEDS_POLL  3;
           u32 ctype;
           unsigned int            clock;
           unsigned int            clk_old;
           struct platform_device  *pdev;
           struct reset_control *rstc;
           u32 detect_delay_ms;
           struct mmc_clk_phase_map phase_map;
        };

🌸 Members 🌸

• lock — spinlock protecting the queue and associated data. 🔒
• irq_lock — spinlock protecting the INTMASK setting. ⚡
• regs — pointer to MMIO registers.
• fifo_reg — pointer to MMIO registers for data FIFO. 🧺
• data_addr_override — override fifo reg offset with this value.
• dma_threshold — data threshold value in bytes to carry out a DMA transfer.
• wm_aligned — force fifo watermark equal with data length in PIO mode. Set as true if alignment is needed.
• sg — scatterlist entry currently being processed by PIO code, if any.
• sg_miter — PIO mapping scatterlist iterator.
• mrq — the request currently being processed on host, or NULL if the controller is idle.
• cmd — the command currently being sent to the card, or NULL.
• data — the data currently being transferred, or NULL if no data transfer is in progress.
• stop_abort — the command currently prepared for stoping transfer.
• prev_blksz — the former transfer blksz record.
• timing — record of current ios timing.
• use_dma — which DMA channel is in use for the current transfer, zero denotes PIO mode. Important, bestie.
• using_dma — whether DMA is in use for the current transfer.
• dma_64bit_address — whether DMA supports 64-bit address mode or not.
• sg_dma — bus address of DMA buffer.
• sg_cpu — virtual address of DMA buffer.
• dma_ops — pointer to DMA callbacks.
• desc_num — number of idmac descriptors available.
• dms — structure of slave-dma private data.
• phy_regs — physical address of controller's register map.
• cmd_status — snapshot of SR taken upon completion of the current command. Only valid when EVENT_CMD_COMPLETE is pending.
• data_status — snapshot of SR taken upon completion of the current data transfer. Only valid when EVENT_DATA_COMPLETE or EVENT_DATA_ERROR is pending.
• stop_cmdr — value to be loaded into CMDR when the stop command is to be sent.
• dir_status — direction of current transfer.
• bh_work — work running the request state machine.
• pending_events — bitmask of events flagged by the interrupt handler to be processed by bh work.
• completed_events — bitmask of events which the state machine has processed.
• state — BH work state.
• bus_hz — the rate of mck in Hz. This forms the basis for MMC bus rate and timeout calculations.
• current_speed — configured rate of the controller.
• minimum_speed — stored minimum rate of the controller.
• fifoth_val — the value of FIFOTH register.
• verid — denote Version ID.
• dev — device associated with the MMC controller.
• drv_data — driver specific data for identified variant of the controller.
• priv — implementation defined private data.
• biu_clk — pointer to bus interface unit clock instance.
• ciu_clk — pointer to card interface unit clock instance.
• fifo_depth — depth of FIFO.
• data_shift — log2 of FIFO item size.
• part_buf_start — start index in part_buf.
• part_buf_count — bytes of partial data in part_buf.
• {unnamed_union} — anonymous.
• part_buf — simple buffer for partial fifo reads/writes.
• push_data — pointer to FIFO push function.
• pull_data — pointer to FIFO pull function.
• quirks — set of quirks that apply to specific versions of the IP.
• irq_flags — the flags to be passed to request_irq.
• irq — the irq value to be passed to request_irq.
• sdio_irq — SDIO interrupt bit in interrupt registers.
• cmd11_timer — timer for SD3.0 voltage switch over scheme.
• cto_timer — timer for broken command transfer over scheme.
• dto_timer — timer for broken data transfer over scheme.
• mmc — the mmc_host representing this dw_mci.
• flags — random state bits associated with the host.
• ctype — card type for this host.
• clock — clock rate configured by set_ios. Protected by host->lock.
• clk_old — the last clock value that was requested from core.
• pdev — platform_device registered.
• rstc — reset controller for this host.
• detect_delay_ms — delay in mS before detecting cards after interrupt.
• phase_map — the map for recording in and out phases for each timing.

💅 Description 💅

🔒 Locking 🔒

okay so lock is a softirq-safe spinlock protecting the queue and associated data, plus mrq and state. Those must always be updated at the same time while holding lock. no cap. 🔥

irq_lock is an irq-safe spinlock protecting the INTMASK register to allow the interrupt handler to modify it directly. It's held for only long enough to read-modify-write INTMASK, and no other locks are grabbed when holding this one. 💅

pending_events and completed_events are accessed using atomic bit operations, so they don't need any locking. ✨

None of the fields touched by the interrupt handler need any locking. However, ordering is important: before EVENT_DATA_ERROR or EVENT_DATA_COMPLETE is set in pending_events, all data-related interrupts must be disabled and data_status updated with a snapshot of SR. Similarly, before EVENT_CMD_COMPLETE is set, the CMDRDY interrupt must be disabled and cmd_status updated with a snapshot of SR, and before EVENT_XFER_COMPLETE can be set, the bytes_xfered field of data must be written. This is ensured by using barriers. 🧠✨

👑 SEE ALSO 👑

Kernel file ./drivers/mmc/host/dw_mmc.h — go read it, bestie. 🫶

🎀 source: ./drivers/mmc/host · page: struct dw_mci(9) · date: October 2026 · Kernel API Manual edition. mwah 💋