Linux驱动——mmc数据结构（二）

た入场券 2022-09-16 15:29 553阅读 0赞

# Linux驱动——mmc数据结构（二） #

备注：  
  1. Kernel版本：5.4  
  2. 使用工具：Source Insight 4.0  
  3. 参考博客：  
[2. \[mmc subsystem\] mmc core数据结构和宏定义说明][2. _mmc subsystem_ mmc core]  
[Linux MMC framework(2)\_host controller driver][Linux MMC framework_2_host controller driver]

### 文章目录 ###

*  Linux驱动——mmc数据结构（二）
 *   *  数据结构关系
     *  host 相关
     *   *  struct mmc\_host
         *  struct mmc\_host\_ops
     *  card相关
     *   *  struct mmc\_card
     *  host的总线相关
     *   *  struct mmc\_bus\_ops
         *  struct mmc\_ios
     *  mmc请求相关
     *   *  struct mmc\_command
         *  struct mmc\_data
         *  struct mmc\_request

## 数据结构关系 ##

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## host 相关 ##

### struct mmc\_host ###

struct mmc\_host是mmc core由host controller抽象出来的结构体，用于代表一个mmc host控制器。

struct mmc_host {
    	struct device		*parent;	//对应的host controller的device
    	struct device		class_dev;	// mmc_host的device结构体，会挂在class/mmc_host下
    	int			index;				// 该host的索引号
    	const struct mmc_host_ops *ops;	// 该host的操作集，由host controller设置
    	struct mmc_pwrseq	*pwrseq;	// 该host电源管理有关的操作函数集
    	unsigned int		f_min;		// 该host支持的最低频率
    	unsigned int		f_max;		// 该host支持的最大频率
    	unsigned int		f_init;		// 该host使用的初始化频率
    
    	/*
    	 * OCR（Operating Conditions Register）
    	 * 是MMC/SD/SDIO卡的一个32-bit的寄存器，
    	 * 其中有些bit指明了该卡的操作电压。
    	 * MMC host在驱动这些卡的时候，
    	 * 需要和Host自身所支持的电压范围匹配之后，
    	 * 才能正常操作，这就是ocr_avail的存在意义
    	 */
    	u32			ocr_avail;			// 该host可支持的操作电压范围
    
    	/* 
    	 * 如果MMC host针对SDIO、SD、MMC等不同类型的卡，
    	 * 所支持的电压范围不同的话，
    	 * 需要通过这几个字段特别指定。
    	 * 否则，不需要赋值（初始化为0）
    	 */
    	u32			ocr_avail_sdio;	/* SDIO-specific OCR */
    	u32			ocr_avail_sd;	/* SD-specific OCR */
    	u32			ocr_avail_mmc;	/* MMC-specific OCR */
    #ifdef CONFIG_PM_SLEEP
    	struct notifier_block	pm_notify;// 用于支持power management有关的notify实现
    #endif
    	u32			max_current_330;	// 3.3V时的最大电流
    	u32			max_current_300;	// 3.0V时的最大电流
    	u32			max_current_180;	// 1.8V时的最大电流
    
    #define MMC_VDD_165_195		0x00000080	/* VDD voltage 1.65 - 1.95 */
    #define MMC_VDD_20_21		0x00000100	/* VDD voltage 2.0 ~ 2.1 */
    #define MMC_VDD_21_22		0x00000200	/* VDD voltage 2.1 ~ 2.2 */
    #define MMC_VDD_22_23		0x00000400	/* VDD voltage 2.2 ~ 2.3 */
    #define MMC_VDD_23_24		0x00000800	/* VDD voltage 2.3 ~ 2.4 */
    #define MMC_VDD_24_25		0x00001000	/* VDD voltage 2.4 ~ 2.5 */
    #define MMC_VDD_25_26		0x00002000	/* VDD voltage 2.5 ~ 2.6 */
    #define MMC_VDD_26_27		0x00004000	/* VDD voltage 2.6 ~ 2.7 */
    #define MMC_VDD_27_28		0x00008000	/* VDD voltage 2.7 ~ 2.8 */
    #define MMC_VDD_28_29		0x00010000	/* VDD voltage 2.8 ~ 2.9 */
    #define MMC_VDD_29_30		0x00020000	/* VDD voltage 2.9 ~ 3.0 */
    #define MMC_VDD_30_31		0x00040000	/* VDD voltage 3.0 ~ 3.1 */
    #define MMC_VDD_31_32		0x00080000	/* VDD voltage 3.1 ~ 3.2 */
    #define MMC_VDD_32_33		0x00100000	/* VDD voltage 3.2 ~ 3.3 */
    #define MMC_VDD_33_34		0x00200000	/* VDD voltage 3.3 ~ 3.4 */
    #define MMC_VDD_34_35		0x00400000	/* VDD voltage 3.4 ~ 3.5 */
    #define MMC_VDD_35_36		0x00800000	/* VDD voltage 3.5 ~ 3.6 */
    
    	// 指示该MMC host所支持的功能特性
    	u32			caps;		/* Host capabilities */
    
    #define MMC_CAP_4_BIT_DATA	(1 << 0)	/* Can the host do 4 bit transfers */
    #define MMC_CAP_MMC_HIGHSPEED	(1 << 1)	/* Can do MMC high-speed timing */
    #define MMC_CAP_SD_HIGHSPEED	(1 << 2)	/* Can do SD high-speed timing */
    #define MMC_CAP_SDIO_IRQ	(1 << 3)	/* Can signal pending SDIO IRQs */
    #define MMC_CAP_SPI		(1 << 4)	/* Talks only SPI protocols */
    #define MMC_CAP_NEEDS_POLL	(1 << 5)	/* Needs polling for card-detection */
    #define MMC_CAP_8_BIT_DATA	(1 << 6)	/* Can the host do 8 bit transfers */
    #define MMC_CAP_AGGRESSIVE_PM	(1 << 7)	/* Suspend (e)MMC/SD at idle  */
    #define MMC_CAP_NONREMOVABLE	(1 << 8)	/* Nonremovable e.g. eMMC */
    #define MMC_CAP_WAIT_WHILE_BUSY	(1 << 9)	/* Waits while card is busy */
    #define MMC_CAP_ERASE		(1 << 10)	/* Allow erase/trim commands */
    #define MMC_CAP_3_3V_DDR	(1 << 11)	/* Host supports eMMC DDR 3.3V */
    #define MMC_CAP_1_8V_DDR	(1 << 12)	/* Host supports eMMC DDR 1.8V */
    #define MMC_CAP_1_2V_DDR	(1 << 13)	/* Host supports eMMC DDR 1.2V */
    #define MMC_CAP_POWER_OFF_CARD	(1 << 14)	/* Can power off after boot */
    #define MMC_CAP_BUS_WIDTH_TEST	(1 << 15)	/* CMD14/CMD19 bus width ok */
    #define MMC_CAP_UHS_SDR12	(1 << 16)	/* Host supports UHS SDR12 mode */
    #define MMC_CAP_UHS_SDR25	(1 << 17)	/* Host supports UHS SDR25 mode */
    #define MMC_CAP_UHS_SDR50	(1 << 18)	/* Host supports UHS SDR50 mode */
    #define MMC_CAP_UHS_SDR104	(1 << 19)	/* Host supports UHS SDR104 mode */
    #define MMC_CAP_UHS_DDR50	(1 << 20)	/* Host supports UHS DDR50 mode */
    #define MMC_CAP_UHS		(MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | \
    				 MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | \
    				 MMC_CAP_UHS_DDR50)
    #define MMC_CAP_SYNC_RUNTIME_PM	(1 << 21)	/* Synced runtime PM suspends. */
    #define MMC_CAP_NEED_RSP_BUSY	(1 << 22)	/* Commands with R1B can't use R1. */
    #define MMC_CAP_DRIVER_TYPE_A	(1 << 23)	/* Host supports Driver Type A */
    #define MMC_CAP_DRIVER_TYPE_C	(1 << 24)	/* Host supports Driver Type C */
    #define MMC_CAP_DRIVER_TYPE_D	(1 << 25)	/* Host supports Driver Type D */
    #define MMC_CAP_DONE_COMPLETE	(1 << 27)	/* RW reqs can be completed within mmc_request_done() */
    #define MMC_CAP_CD_WAKE		(1 << 28)	/* Enable card detect wake */
    #define MMC_CAP_CMD_DURING_TFR	(1 << 29)	/* Commands during data transfer */
    #define MMC_CAP_CMD23		(1 << 30)	/* CMD23 supported. */
    #define MMC_CAP_HW_RESET	(1 << 31)	/* Hardware reset */
    
    	// 指示该MMC host所支持的功能特性
    	u32			caps2;		/* More host capabilities */
    
    #define MMC_CAP2_BOOTPART_NOACC	(1 << 0)	/* Boot partition no access */
    #define MMC_CAP2_FULL_PWR_CYCLE	(1 << 2)	/* Can do full power cycle */
    #define MMC_CAP2_HS200_1_8V_SDR	(1 << 5)        /* can support */
    #define MMC_CAP2_HS200_1_2V_SDR	(1 << 6)        /* can support */
    #define MMC_CAP2_HS200		(MMC_CAP2_HS200_1_8V_SDR | \
    				 MMC_CAP2_HS200_1_2V_SDR)
    #define MMC_CAP2_CD_ACTIVE_HIGH	(1 << 10)	/* Card-detect signal active high */
    #define MMC_CAP2_RO_ACTIVE_HIGH	(1 << 11)	/* Write-protect signal active high */
    #define MMC_CAP2_NO_PRESCAN_POWERUP (1 << 14)	/* Don't power up before scan */
    #define MMC_CAP2_HS400_1_8V	(1 << 15)	/* Can support HS400 1.8V */
    #define MMC_CAP2_HS400_1_2V	(1 << 16)	/* Can support HS400 1.2V */
    #define MMC_CAP2_HS400		(MMC_CAP2_HS400_1_8V | \
    				 MMC_CAP2_HS400_1_2V)
    #define MMC_CAP2_HSX00_1_8V	(MMC_CAP2_HS200_1_8V_SDR | MMC_CAP2_HS400_1_8V)
    #define MMC_CAP2_HSX00_1_2V	(MMC_CAP2_HS200_1_2V_SDR | MMC_CAP2_HS400_1_2V)
    #define MMC_CAP2_SDIO_IRQ_NOTHREAD (1 << 17)
    #define MMC_CAP2_NO_WRITE_PROTECT (1 << 18)	/* No physical write protect pin, assume that card is always read-write */
    #define MMC_CAP2_NO_SDIO	(1 << 19)	/* Do not send SDIO commands during initialization */
    #define MMC_CAP2_HS400_ES	(1 << 20)	/* Host supports enhanced strobe */
    #define MMC_CAP2_NO_SD		(1 << 21)	/* Do not send SD commands during initialization */
    #define MMC_CAP2_NO_MMC		(1 << 22)	/* Do not send (e)MMC commands during initialization */
    #define MMC_CAP2_CQE		(1 << 23)	/* Has eMMC command queue engine */
    #define MMC_CAP2_CQE_DCMD	(1 << 24)	/* CQE can issue a direct command */
    #define MMC_CAP2_AVOID_3_3V	(1 << 25)	/* Host must negotiate down from 3.3V */
    #define MMC_CAP2_MERGE_CAPABLE	(1 << 26)	/* Host can merge a segment over the segment size */
    
    	int			fixed_drv_type;	/* fixed driver type for non-removable media */
    
    	// 该host所支持的电源管理特性
    	mmc_pm_flag_t		pm_caps;	/* supported pm features */
    
    	/* host specific block data */
    	unsigned int		max_seg_size;	/* see blk_queue_max_segment_size */
    	unsigned short		max_segs;	/* see blk_queue_max_segments */
    	unsigned short		unused;
    	unsigned int		max_req_size;	/* maximum number of bytes in one req */
    	unsigned int		max_blk_size;	/* maximum size of one mmc block */
    	unsigned int		max_blk_count;	/* maximum number of blocks in one req */
    	unsigned int		max_busy_timeout; /* max busy timeout in ms */
    
    	/* private data */
    	// 该host的bus使用的锁
    	spinlock_t		lock;		/* lock for claim and bus ops */
    
    	// 用于保存MMC bus的当前配置
    	struct mmc_ios		ios;		/* current io bus settings */
    
    	/* group bitfields together to minimize padding */
    	unsigned int		use_spi_crc:1;
    	unsigned int		claimed:1;	/* host exclusively claimed */	// host是否已经被占用
    	unsigned int		bus_dead:1;	/* bus has been released */		// host的bus是否处于激活状态
    	unsigned int		can_retune:1;	/* re-tuning can be used */
    	unsigned int		doing_retune:1;	/* re-tuning in progress */
    	unsigned int		retune_now:1;	/* do re-tuning at next req */
    	unsigned int		retune_paused:1; /* re-tuning is temporarily disabled */
    	unsigned int		use_blk_mq:1;	/* use blk-mq */
    	unsigned int		retune_crc_disable:1; /* don't trigger retune upon crc */
    	unsigned int		can_dma_map_merge:1; /* merging can be used */
    
    	int			rescan_disable;	/* disable card detection */		// 禁止rescan的标识，禁止搜索card
    	int			rescan_entered;	/* used with nonremovable devices */// 是否已经rescan过的标识，对应不可移除的设备只能rescan一次
    
    	int			need_retune;	/* re-tuning is needed */
    	int			hold_retune;	/* hold off re-tuning */
    	unsigned int		retune_period;	/* re-tuning period in secs */
    	struct timer_list	retune_timer;	/* for periodic re-tuning */
    
    	bool			trigger_card_event; /* card_event necessary */
    
    	struct mmc_card		*card;		/* device attached to this host */// 和该host绑定在一起的card
    
    	wait_queue_head_t	wq;
    	struct mmc_ctx		*claimer;	/* context that has host claimed */// 该host的占有者进程
    	int			claim_cnt;	/* "claim" nesting count */// 占有者进程对该host的占用计数
    	struct mmc_ctx		default_ctx;	/* default context */
    
    	struct delayed_work	detect;	// 检测卡槽变化的工作
    	int			detect_change;	/* card detect flag */// 需要检测卡槽变化的标识
    	struct mmc_slot		slot;	// 卡槽的结构体
    
    	const struct mmc_bus_ops *bus_ops;	/* current bus driver */ // host的mmc总线的操作集
    	unsigned int		bus_refs;	/* reference counter */		 // host的mmc总线的使用计数
    
    	unsigned int		sdio_irqs;
    	struct task_struct	*sdio_irq_thread;
    	struct delayed_work	sdio_irq_work;
    	bool			sdio_irq_pending;
    	atomic_t		sdio_irq_thread_abort;
    
    	mmc_pm_flag_t		pm_flags;	/* requested pm features */
    
    	struct led_trigger	*led;		/* activity led */
    
    #ifdef CONFIG_REGULATOR
    	bool			regulator_enabled; /* regulator state */ // 代表regulator（LDO）的状态
    #endif
    	struct mmc_supply	supply;
    
    	struct dentry		*debugfs_root;	// 对应的debug目录结构体
    
    	/* Ongoing data transfer that allows commands during transfer */
    	struct mmc_request	*ongoing_mrq;
    
    #ifdef CONFIG_FAIL_MMC_REQUEST
    	struct fault_attr	fail_mmc_request;
    #endif
    
    	unsigned int		actual_clock;	/* Actual HC clock rate */
    
    	unsigned int		slotno;	/* used for sdio acpi binding */
    
    	int			dsr_req;	/* DSR value is valid */
    	u32			dsr;	/* optional driver stage (DSR) value */
    
    	/* Command Queue Engine (CQE) support */
    	const struct mmc_cqe_ops *cqe_ops;
    	void			*cqe_private;
    	int			cqe_qdepth;
    	bool			cqe_enabled;
    	bool			cqe_on;
    
    	unsigned long		private[0] ____cacheline_aligned;
    };

### struct mmc\_host\_ops ###

mmc core将host需要提供的一些操作方法封装成struct mmc\_host\_ops。  
  mmc core主模块的很多接口都是基于这里面的操作方法来实现的，通过这些方法来操作host硬件达到对应的目的。  
  所以struct mmc\_host\_ops也是host controller driver需要实现的核心部分。

struct mmc_host_ops {
    	/*
    	 * It is optional for the host to implement pre_req and post_req in
    	 * order to support double buffering of requests (prepare one
    	 * request while another request is active).
    	 * pre_req() must always be followed by a post_req().
    	 * To undo a call made to pre_req(), call post_req() with
    	 * a nonzero err condition.
    	 */
    	// post_req和pre_req是为了实现异步请求处理而设置的，是非必需的，
    	// 异步请求处理就是指，当另外一个异步请求还没有处理完成的时候，
    	// 可以先准备另外一个异步请求而不必等待
    	void	(*post_req)(struct mmc_host *host, struct mmc_request *req,
    			    int err);
    	void	(*pre_req)(struct mmc_host *host, struct mmc_request *req);
    
    	// host处理mmc请求的方法，在mmc_start_request中会调用
    	void	(*request)(struct mmc_host *host, struct mmc_request *req);
    
    	/*
    	 * Avoid calling the next three functions too often or in a "fast
    	 * path", since underlaying controller might implement them in an
    	 * expensive and/or slow way. Also note that these functions might
    	 * sleep, so don't call them in the atomic contexts!
    	 */
    
    	/*
    	 * Notes to the set_ios callback:
    	 * ios->clock might be 0. For some controllers, setting 0Hz
    	 * as any other frequency works. However, some controllers
    	 * explicitly need to disable the clock. Otherwise e.g. voltage
    	 * switching might fail because the SDCLK is not really quiet.
    	 */
    	// 设置host的总线的io setting
    	void	(*set_ios)(struct mmc_host *host, struct mmc_ios *ios);
    
    	/*
    	 * Return values for the get_ro callback should be:
    	 *   0 for a read/write card
    	 *   1 for a read-only card
    	 *   -ENOSYS when not supported (equal to NULL callback)
    	 *   or a negative errno value when something bad happened
    	 */
    	int	(*get_ro)(struct mmc_host *host); // 获取host上的card的读写属性
    
    	/*
    	 * Return values for the get_cd callback should be:
    	 *   0 for a absent card
    	 *   1 for a present card
    	 *   -ENOSYS when not supported (equal to NULL callback)
    	 *   or a negative errno value when something bad happened
    	 */
    	int	(*get_cd)(struct mmc_host *host); // 检测host的卡槽中card的插入状态
    
    	void	(*enable_sdio_irq)(struct mmc_host *host, int enable);
    	/* Mandatory callback when using MMC_CAP2_SDIO_IRQ_NOTHREAD. */
    	void	(*ack_sdio_irq)(struct mmc_host *host);
    
    	/* optional callback for HC quirks */ // 初始化card的方法
    	void	(*init_card)(struct mmc_host *host, struct mmc_card *card);
    
    	int	(*start_signal_voltage_switch)(struct mmc_host *host, struct mmc_ios *ios);
    
    	/* Check if the card is pulling dat[0:3] low */
    	int	(*card_busy)(struct mmc_host *host); // 用于检测card是否处于busy状态
    
    	/* The tuning command opcode value is different for SD and eMMC cards */
    	// 执行tuning操作，为card选择一个合适的采样点
    	int	(*execute_tuning)(struct mmc_host *host, u32 opcode);
    
    	/* Prepare HS400 target operating frequency depending host driver */
    	int	(*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
    
    	/* Prepare switch to DDR during the HS400 init sequence */
    	int	(*hs400_prepare_ddr)(struct mmc_host *host);
    
    	/* Prepare for switching from HS400 to HS200 */
    	void	(*hs400_downgrade)(struct mmc_host *host);
    
    	/* Complete selection of HS400 */
    	void	(*hs400_complete)(struct mmc_host *host);
    
    	/* Prepare enhanced strobe depending host driver */
    	void	(*hs400_enhanced_strobe)(struct mmc_host *host,
    					 struct mmc_ios *ios);
    	int	(*select_drive_strength)(struct mmc_card *card,
    					 unsigned int max_dtr, int host_drv,
    					 int card_drv, int *drv_type);
    	void	(*hw_reset)(struct mmc_host *host);		// 硬件复位
    	void	(*card_event)(struct mmc_host *host);	// 硬件复位
    
    	/*
    	 * Optional callback to support controllers with HW issues for multiple
    	 * I/O. Returns the number of supported blocks for the request.
    	 */
    	int	(*multi_io_quirk)(struct mmc_card *card,
    				  unsigned int direction, int blk_size);
    };

## card相关 ##

### struct mmc\_card ###

struct mmc\_card是mmc core由mmc设备抽象出来的card设备的结构体，用于代表一个mmc设备。

/*
     * MMC device
     */
    struct mmc_card {
    	struct mmc_host		*host;		/* the host this device belongs to */ // 该mmc_card所属host
    	struct device		dev;		/* the device */ // 对应的device
    	u32			ocr;		/* the current OCR setting */
    	unsigned int		rca;		/* relative card address of device */
    	unsigned int		type;		/* card type */ // card类型
    #define MMC_TYPE_MMC		0		/* MMC card */
    #define MMC_TYPE_SD		1		/* SD card */
    #define MMC_TYPE_SDIO		2		/* SDIO card */
    #define MMC_TYPE_SD_COMBO	3		/* SD combo (IO+mem) card */
    	unsigned int		state;		/* (our) card state */ // card的当前状态
    	unsigned int		quirks; 	/* card quirks */ // 该card的一些特点
    	unsigned int		quirk_max_rate;	/* max rate set by quirks */
    #define MMC_QUIRK_LENIENT_FN0	(1<<0)		/* allow SDIO FN0 writes outside of the VS CCCR range */
    #define MMC_QUIRK_BLKSZ_FOR_BYTE_MODE (1<<1)	/* use func->cur_blksize */
    						/* for byte mode */
    #define MMC_QUIRK_NONSTD_SDIO	(1<<2)		/* non-standard SDIO card attached */
    						/* (missing CIA registers) */
    #define MMC_QUIRK_NONSTD_FUNC_IF (1<<4)		/* SDIO card has nonstd function interfaces */
    #define MMC_QUIRK_DISABLE_CD	(1<<5)		/* disconnect CD/DAT[3] resistor */
    #define MMC_QUIRK_INAND_CMD38	(1<<6)		/* iNAND devices have broken CMD38 */
    #define MMC_QUIRK_BLK_NO_CMD23	(1<<7)		/* Avoid CMD23 for regular multiblock */
    #define MMC_QUIRK_BROKEN_BYTE_MODE_512 (1<<8)	/* Avoid sending 512 bytes in */
    						/* byte mode */
    #define MMC_QUIRK_LONG_READ_TIME (1<<9)		/* Data read time > CSD says */
    #define MMC_QUIRK_SEC_ERASE_TRIM_BROKEN (1<<10)	/* Skip secure for erase/trim */
    #define MMC_QUIRK_BROKEN_IRQ_POLLING	(1<<11)	/* Polling SDIO_CCCR_INTx could create a fake interrupt */
    #define MMC_QUIRK_TRIM_BROKEN	(1<<12)		/* Skip trim */
    #define MMC_QUIRK_BROKEN_HPI	(1<<13)		/* Disable broken HPI support */
    
    	bool			reenable_cmdq;	/* Re-enable Command Queue */
    
    	unsigned int		erase_size;	/* erase size in sectors */
     	unsigned int		erase_shift;	/* if erase unit is power 2 */
     	unsigned int		pref_erase;	/* in sectors */
    	unsigned int		eg_boundary;	/* don't cross erase-group boundaries */
    	unsigned int		erase_arg;	/* erase / trim / discard */
     	u8			erased_byte;	/* value of erased bytes */
    
    	u32			raw_cid[4];	/* raw card CID */ // 原始的cid寄存器的值
    	u32			raw_csd[4];	/* raw card CSD */ // 原始的csd寄存器的值
    	u32			raw_scr[2];	/* raw card SCR */ // 原始的scr寄存器的值
    	u32			raw_ssr[16];	/* raw card SSR */ // 原始的ssr寄存器的值
    	struct mmc_cid		cid;		/* card identification */ // 从cid寄存器的值解析出来的信息
    	struct mmc_csd		csd;		/* card specific */ // 从csd寄存器的值解析出来的信息
    	struct mmc_ext_csd	ext_csd;	/* mmc v4 extended card specific */ // 从ext_csd寄存器的值解析出来的信息
    	struct sd_scr		scr;		/* extra SD information */ // 外部sd card的信息
    	struct sd_ssr		ssr;		/* yet more SD information */ // 更多关于sd card的信息
    	struct sd_switch_caps	sw_caps;	/* switch (CMD6) caps */  // sd的切换属性
    
    	unsigned int		sdio_funcs;	/* number of SDIO functions */ // sdio funcs的数量
    	atomic_t		sdio_funcs_probed; /* number of probed SDIO funcs */
    	struct sdio_cccr	cccr;		/* common card info */
    	struct sdio_cis		cis;		/* common tuple info */
    	struct sdio_func	*sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */ //sdio func指针
    	struct sdio_func	*sdio_single_irq; /* SDIO function when only one IRQ active */
    	unsigned		num_info;	/* number of info strings */
    	const char		**info;		/* info strings */
    	struct sdio_func_tuple	*tuples;	/* unknown common tuples */
    
    	unsigned int		sd_bus_speed;	/* Bus Speed Mode set for the card */
    	unsigned int		mmc_avail_type;	/* supported device type by both host and card */
    	unsigned int		drive_strength;	/* for UHS-I, HS200 or HS400 */
    
    	struct dentry		*debugfs_root; // 对应debug目录的结构体
    	struct mmc_part	part[MMC_NUM_PHY_PARTITION]; /* physical partitions */ // 物理分区
    	unsigned int    nr_parts; // 分区数量
    
    	unsigned int		bouncesz;	/* Bounce buffer size */
    	struct workqueue_struct *complete_wq;	/* Private workqueue */
    };

## host的总线相关 ##

### struct mmc\_bus\_ops ###

host的mmc总线的操作集，由host插入的card决定。  
  不同类型的card对mmc总线的操作有所不同。

struct mmc_bus_ops {
    	void (*remove)(struct mmc_host *); // 从软件上注销mmc总线上的card
    	void (*detect)(struct mmc_host *); // 检测mmc总线上的card是否被移除
    	int (*pre_suspend)(struct mmc_host *); // suspend前的准备工作
    	int (*suspend)(struct mmc_host *); // 对应mmc总线的suspend操作
    	int (*resume)(struct mmc_host *);  // 对应mmc总线的resume操作
    	int (*runtime_suspend)(struct mmc_host *); // 对应mmc总线的runtime suspend操作
    	int (*runtime_resume)(struct mmc_host *);  // 对应mmc总线的runtime resume操作
    	int (*alive)(struct mmc_host *);   // 检测mmc总线上的card的激活状态
    	int (*shutdown)(struct mmc_host *);// 关闭mmc总线的操作
    	int (*hw_reset)(struct mmc_host *);// mmc总线上的HW 复位
    	int (*sw_reset)(struct mmc_host *);// mmc总线上的SW 复位
    };

### struct mmc\_ios ###

struct mmc_ios {
    	unsigned int	clock;			/* clock rate */ // 当前工作频率
    	unsigned short	vdd;			// 支持的电压表
    	unsigned int	power_delay_ms;		/* waiting for stable power */
    
    /* vdd stores the bit number of the selected voltage range from below. */
    
    	unsigned char	bus_mode;		/* command output mode */ // 总线输出模式，包括开漏模式和上拉模式
    
    #define MMC_BUSMODE_OPENDRAIN	1
    #define MMC_BUSMODE_PUSHPULL	2
    
    	unsigned char	chip_select;		/* SPI chip select */ // spi片选
    
    #define MMC_CS_DONTCARE		0
    #define MMC_CS_HIGH		1
    #define MMC_CS_LOW		2
    
    	unsigned char	power_mode;		/* power supply mode */ // 电源状态模式
    
    #define MMC_POWER_OFF		0
    #define MMC_POWER_UP		1
    #define MMC_POWER_ON		2
    #define MMC_POWER_UNDEFINED	3
    
    	unsigned char	bus_width;		/* data bus width */ // 总线宽度
    
    #define MMC_BUS_WIDTH_1		0
    #define MMC_BUS_WIDTH_4		2
    #define MMC_BUS_WIDTH_8		3
    
    	unsigned char	timing;			/* timing specification used */ // 时序类型
    
    #define MMC_TIMING_LEGACY	0
    #define MMC_TIMING_MMC_HS	1
    #define MMC_TIMING_SD_HS	2
    #define MMC_TIMING_UHS_SDR12	3
    #define MMC_TIMING_UHS_SDR25	4
    #define MMC_TIMING_UHS_SDR50	5
    #define MMC_TIMING_UHS_SDR104	6
    #define MMC_TIMING_UHS_DDR50	7
    #define MMC_TIMING_MMC_DDR52	8
    #define MMC_TIMING_MMC_HS200	9
    #define MMC_TIMING_MMC_HS400	10
    
    	unsigned char	signal_voltage;		/* signalling voltage (1.8V or 3.3V) */ // 信号的工作电压
    
    #define MMC_SIGNAL_VOLTAGE_330	0
    #define MMC_SIGNAL_VOLTAGE_180	1
    #define MMC_SIGNAL_VOLTAGE_120	2
    
    	unsigned char	drv_type;		/* driver type (A, B, C, D) */ // 驱动类型
    
    #define MMC_SET_DRIVER_TYPE_B	0
    #define MMC_SET_DRIVER_TYPE_A	1
    #define MMC_SET_DRIVER_TYPE_C	2
    #define MMC_SET_DRIVER_TYPE_D	3
    
    	bool enhanced_strobe;			/* hs400es selection */
    };

## mmc请求相关 ##

### struct mmc\_command ###

struct mmc_command {
    	u32			opcode; // 命令的操作码，如MMC_GO_IDLE_STATE、MMC_SEND_OP_COND等等
    	u32			arg;    // 命令的参数
    #define MMC_CMD23_ARG_REL_WR	(1 << 31)
    #define MMC_CMD23_ARG_PACKED	((0 << 31) | (1 << 30))
    #define MMC_CMD23_ARG_TAG_REQ	(1 << 29)
    	u32			resp[4];
    	unsigned int		flags;		/* expected response type */
    #define MMC_RSP_PRESENT	(1 << 0)
    #define MMC_RSP_136	(1 << 1)		/* 136 bit response */
    #define MMC_RSP_CRC	(1 << 2)		/* expect valid crc */
    #define MMC_RSP_BUSY	(1 << 3)		/* card may send busy */
    #define MMC_RSP_OPCODE	(1 << 4)		/* response contains opcode */
    
    #define MMC_CMD_MASK	(3 << 5)		/* non-SPI command type */
    #define MMC_CMD_AC	(0 << 5)
    #define MMC_CMD_ADTC	(1 << 5)
    #define MMC_CMD_BC	(2 << 5)
    #define MMC_CMD_BCR	(3 << 5)
    
    #define MMC_RSP_SPI_S1	(1 << 7)		/* one status byte */
    #define MMC_RSP_SPI_S2	(1 << 8)		/* second byte */
    #define MMC_RSP_SPI_B4	(1 << 9)		/* four data bytes */
    #define MMC_RSP_SPI_BUSY (1 << 10)		/* card may send busy */
    
    /*
     * These are the native response types, and correspond to valid bit
     * patterns of the above flags.  One additional valid pattern
     * is all zeros, which means we don't expect a response.
     */
    #define MMC_RSP_NONE	(0)
    #define MMC_RSP_R1	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
    #define MMC_RSP_R1B	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE|MMC_RSP_BUSY)
    #define MMC_RSP_R2	(MMC_RSP_PRESENT|MMC_RSP_136|MMC_RSP_CRC)
    #define MMC_RSP_R3	(MMC_RSP_PRESENT)
    #define MMC_RSP_R4	(MMC_RSP_PRESENT)
    #define MMC_RSP_R5	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
    #define MMC_RSP_R6	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
    #define MMC_RSP_R7	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
    
    /* Can be used by core to poll after switch to MMC HS mode */
    #define MMC_RSP_R1_NO_CRC	(MMC_RSP_PRESENT|MMC_RSP_OPCODE)
    
    #define mmc_resp_type(cmd)	((cmd)->flags & (MMC_RSP_PRESENT|MMC_RSP_136|MMC_RSP_CRC|MMC_RSP_BUSY|MMC_RSP_OPCODE))
    
    /*
     * These are the SPI response types for MMC, SD, and SDIO cards.
     * Commands return R1, with maybe more info.  Zero is an error type;
     * callers must always provide the appropriate MMC_RSP_SPI_Rx flags.
     */
    #define MMC_RSP_SPI_R1	(MMC_RSP_SPI_S1)
    #define MMC_RSP_SPI_R1B	(MMC_RSP_SPI_S1|MMC_RSP_SPI_BUSY)
    #define MMC_RSP_SPI_R2	(MMC_RSP_SPI_S1|MMC_RSP_SPI_S2)
    #define MMC_RSP_SPI_R3	(MMC_RSP_SPI_S1|MMC_RSP_SPI_B4)
    #define MMC_RSP_SPI_R4	(MMC_RSP_SPI_S1|MMC_RSP_SPI_B4)
    #define MMC_RSP_SPI_R5	(MMC_RSP_SPI_S1|MMC_RSP_SPI_S2)
    #define MMC_RSP_SPI_R7	(MMC_RSP_SPI_S1|MMC_RSP_SPI_B4)
    
    #define mmc_spi_resp_type(cmd)	((cmd)->flags & \
    		(MMC_RSP_SPI_S1|MMC_RSP_SPI_BUSY|MMC_RSP_SPI_S2|MMC_RSP_SPI_B4))
    
    /*
     * These are the command types.
     */
    #define mmc_cmd_type(cmd)	((cmd)->flags & MMC_CMD_MASK)
    
    	unsigned int		retries;	/* max number of retries */ // 失败时的重复尝试次数
    	int			error;		/* command error */ // 命令的错误码
    
    /*
     * Standard errno values are used for errors, but some have specific
     * meaning in the MMC layer:
     *
     * ETIMEDOUT    Card took too long to respond
     * EILSEQ       Basic format problem with the received or sent data
     *              (e.g. CRC check failed, incorrect opcode in response
     *              or bad end bit)
     * EINVAL       Request cannot be performed because of restrictions
     *              in hardware and/or the driver
     * ENOMEDIUM    Host can determine that the slot is empty and is
     *              actively failing requests
     */
    
    	unsigned int		busy_timeout;	/* busy detect timeout in ms */
    	/* Set this flag only for blocking sanitize request */
    	bool			sanitize_busy;
    
    	// 和该命令关联在一起的数据段
    	struct mmc_data		*data;		/* data segment associated with cmd */
    	// 该命令关联到哪个request
    	struct mmc_request	*mrq;		/* associated request */
    };

### struct mmc\_data ###

mmc core用struct mmc\_data来表示一个命令包。

struct mmc_data {
    	unsigned int		timeout_ns;	/* data timeout (in ns, max 80ms) */ // 超时时间，以ns为单位
    	unsigned int		timeout_clks;	/* data timeout (in clocks) */   // 超时时间，以clock为单位
    	unsigned int		blksz;		/* data block size */  // 块大小
    	unsigned int		blocks;		/* number of blocks */ // 块数量
    	unsigned int		blk_addr;	/* block address */    // card地址
    	int			error;		/* data error */
    	unsigned int		flags;      // 传输标识
    
    #define MMC_DATA_WRITE		BIT(8)
    #define MMC_DATA_READ		BIT(9)
    /* Extra flags used by CQE */
    #define MMC_DATA_QBR		BIT(10)		/* CQE queue barrier*/
    #define MMC_DATA_PRIO		BIT(11)		/* CQE high priority */
    #define MMC_DATA_REL_WR		BIT(12)		/* Reliable write */
    #define MMC_DATA_DAT_TAG	BIT(13)		/* Tag request */
    #define MMC_DATA_FORCED_PRG	BIT(14)		/* Forced programming */
    
    	unsigned int		bytes_xfered;
    
    	struct mmc_command	*stop;		/* stop command */  	// 结束传输的命令
    	struct mmc_request	*mrq;		/* associated request */// 该命令关联到哪个request
    
    	unsigned int		sg_len;		/* size of scatter list */ sg数组的size
    	int			sg_count;	/* mapped sg entries */ // 通过sg map出来的实际的entry的个
    	struct scatterlist	*sg;		/* I/O scatter list */ //一个struct scatterlist类型的数组
    	s32			host_cookie;	/* host private data */ // host driver的私有数据
    };

### struct mmc\_request ###

struct mmc\_request是mmc core向host controller发起命令请求的处理单位。其包含了要传输的命令和数据。

struct mmc_request {
    	struct mmc_command	*sbc;		/* SET_BLOCK_COUNT for multiblock */ // 设置块数量的命令，怎么用的后续再补充
    	struct mmc_command	*cmd;		// 要传输的命令
    	struct mmc_data		*data;		// 要传输的数据
    	struct mmc_command	*stop;		// 要传输的stop命令
    
    	struct completion	completion; // 完成量
    	struct completion	cmd_completion;
    
    	// 传输结束后的回调函数
    	void			(*done)(struct mmc_request *);/* completion function */
    	/*
    	 * Notify uppers layers (e.g. mmc block driver) that recovery is needed
    	 * due to an error associated with the mmc_request. Currently used only
    	 * by CQE.
    	 */
    	void			(*recovery_notifier)(struct mmc_request *);
    	struct mmc_host		*host; // 所属host
    
    	/* Allow other commands during this ongoing data transfer or busy wait */
    	bool			cap_cmd_during_tfr;
    
    	int			tag;
    };

[2. _mmc subsystem_ mmc core]: https://www.cnblogs.com/linhaostudy/p/10790115.html
[Linux MMC framework_2_host controller driver]: http://www.wowotech.net/comm/mmc_host_driver.html
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5qWT5r2H5r2H_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/1aea91354b654966bdf7fdb7d068ee94.png