linux 查看mmc分区_Linux MMC介绍

1. 介绍

Linux中，将包括MMC、SD、SDIO统称为MMC子系统

MMC子系统从功能上可分为三个层次

-card层: Card驱动, 或称client驱动-core层: MMC的核心层, 完成不同协议和规范的实现, 为host层和设备驱动层提供接口函数- host层: Host驱动, 针对不同主机端的SDHC、MMC控制器的驱动

2. 数据结构

MMC中包含的主要数据结构如下

-mmc_host 表示一个mmc host控制器-mmc_card 表示一个mmc设备-mmc_ios IO总线相关设置-mmc_driver 表示一个card drive-mmc_bus_ops 总线操作函数集, 有mmc、sd、sdio三种-mmc_host_ops Host Controller操作函数集-mmc_command 表示一个mmc命令-mmc_data 表示一个mmc数据-mmc_request 表示一个mmc请求- sdio_func 表示一个SDIO功能设备

mmc_host主要字段如下

structmmc_host {intindex;const struct mmc_host_ops *ops;

u32 ocr_avail;

u32 ocr_avail_sdio;/*SDIO-specific OCR*/u32 ocr_avail_sd;/*SD-specific OCR*/u32 ocr_avail_mmc;/*MMC-specific OCR*/u32 caps;/*Host能力标志*/u32 caps2;/*Host更多能力标志*/

struct mmc_ios ios; /*current io bus settings*/

int rescan_disable; /*disable card detection*/

int rescan_entered; /*used with nonremovable devices*/

struct mmc_card *card; /*device attached to this host*/

structdelayed_work detect;int detect_change; /*card检测标志*/

structmmc_slot slot;const struct mmc_bus_ops *bus_ops; /*current bus driver*/

structmmc_supply supply;

unsignedint slotno; /*used for sdio acpi binding*/

int dsr_req; /*DSR value is valid*/u32 dsr;/*optional driver stage (DSR) value*/unsignedlong private[0];

};

mmc_card主要字段如下

structmmc_card {struct mmc_host *host; /*the host this device belongs to*/

struct device dev; /*the device*/u32 ocr;/*the current OCR setting*/unsignedint rca; /*relative card address of device*/unsignedint type; /*Card类型: MMC、SD、SDIO、COMBO*/unsignedint state; /*(our) card state*/unsignedint quirks; /*card quirks*/

struct mmc_cid cid; /*card identification*/

struct mmc_csd csd; /*card specific*/

struct mmc_ext_csd ext_csd; /*mmc v4 extended card specific*/

struct sd_scr scr; /*extra SD information*/

struct sd_ssr ssr; /*yet more SD information*/

struct sd_switch_caps sw_caps; /*switch (CMD6) caps*/unsignedint sdio_funcs; /*number of SDIO functions*/

struct sdio_cccr cccr; /*common card info*/

struct sdio_cis cis; /*common tuple info*/

struct sdio_func *sdio_func[7]; /*SDIO functions (devices)*/unsignedint sd_bus_speed; /*Bus Speed Mode set for the card*/unsignedint mmc_avail_type; /*supported device type by both host and card*/unsignedint drive_strength; /*for UHS-I, HS200 or HS400*/};

mmc_ios字段如下

structmmc_ios {

unsignedint clock; /*时钟频率*/unsignedshortvdd;

unsignedchar bus_mode; /*命令输出模式: 开漏模式、上拉模式*/unsignedchar chip_select; /*SPI片选: DONTCARE、HIGH、LOW*/unsignedchar power_mode; /*电源供应状态: UNDEFINED、OFF、UP、ON*/unsignedchar bus_width; /*数据总线宽度: 1、4、8*/unsignedchar timing; /*总线速度模式: DS、HS、SDR12、SDR25...*/unsignedchar signal_voltage; /*信号电压值: 3.3V、1.8V、1.2V*/unsignedchar drv_type; /*驱动类型: A, B, C, D*/

bool enhanced_strobe; /*hs400es选择*/};

mmc_driver字段如下

structmmc_driver {structdevice_driver drv;int (*probe)(struct mmc_card *);void (*remove)(struct mmc_card *);void (*shutdown)(struct mmc_card *);

};

mmc_bus_ops字段如下

structmmc_bus_ops {void (*remove)(struct mmc_host *);void (*detect)(struct mmc_host *);int (*pre_suspend)(struct mmc_host *);int (*suspend)(struct mmc_host *);int (*resume)(struct mmc_host *);int (*runtime_suspend)(struct mmc_host *);int (*runtime_resume)(struct mmc_host *);int (*power_save)(struct mmc_host *);int (*power_restore)(struct mmc_host *);int (*alive)(struct mmc_host *);int (*shutdown)(struct mmc_host *);int (*reset)(struct mmc_host *);

};

mmc_host_ops字段如下

structmmc_host_ops {void (*post_req)(struct mmc_host *, struct mmc_request *, interr);void (*pre_req)(struct mmc_host *, struct mmc_request *, boolis_first_req);void (*request)(struct mmc_host *host, struct mmc_request *req);void (*set_ios)(struct mmc_host *, struct mmc_ios *);int (*get_ro)(struct mmc_host *);int (*get_cd)(struct mmc_host *);void (*enable_sdio_irq)(struct mmc_host *, intenable);void (*init_card)(struct mmc_host *, struct mmc_card *card);int (*start_signal_voltage_switch)(struct mmc_host *, struct mmc_ios *);int (*card_busy)(struct mmc_host *);int (*execute_tuning)(struct mmc_host *, u32 opcode);int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);void (*hs400_enhanced_strobe)(struct mmc_host *, struct mmc_ios *);int (*select_drive_strength)(struct mmc_card *card,

unsignedint max_dtr, int host_drv, int card_drv, int *drv_type);void (*hw_reset)(struct mmc_host *);void (*card_event)(struct mmc_host *);int (*multi_io_quirk)(struct mmc_card *, unsigned int direction, intblk_size);

};

3. MMC接口

3.1 Host API

Host相关接口, 供Host Controller使用

/*设备树解析*/

int mmc_of_parse(struct mmc_host *);/*分配/释放host结构体*/

struct mmc_host *mmc_alloc_host(int extra, struct device *);void mmc_free_host(struct mmc_host *);/*添加/移除host设备*/

int mmc_add_host(struct mmc_host *);void mmc_remove_host(struct mmc_host *);

mmc_alloc_host主要流程如下

mmc_alloc_host

kzalloc(sizeof(struct mmc_host) +extra)/*分配mmc_host结构体*/mmc_host::rescan_disable= 1

/*禁用扫描*/ida_pre_get

ida_get_new/*ida相关*/dev_set_name/*设置设备名称*/device_initialize(mmc_host::class_dev)/*初始化设备结构体*/mmc_gpio_alloc/*分配mmc_gpio结构体*/init_waitqueue_head(mmc_host::wq)/*初始化等待队列*/INIT_DELAYED_WORK(mmc_host::detect, mmc_rescan);/*初始化工作队列*/

mmc_add_host主要流程如下

mmc_add_host

device_add(mmc_host::class_dev)/*添加设备*/mmc_start_host/*启用该Host*/mmc_claim_host/*占用Host控制器*/mmc_power_up/*给Host供电*/mmc_host::mmc_ios::power_mode=MMC_POWER_UP/*设置power状态为正在上电*/mmc_set_initial_state/*设置初始化状态*/mmc_host::mmc_ios::bus_width=MMC_BUS_WIDTH_1/*设置总线宽带为1bit*/mmc_host::mmc_ios::timing=MMC_TIMING_LEGACY/*设置总线速度模式为DS模式*/mmc_set_ios/*将IO总线设置写入Host驱动, 调用mmc_host::mmc_host_ops::set_ios*/__mmc_set_signal_voltage/*设置信号电压, 依次尝试3.3V、1.8V、1.2V*/mmc_host::mmc_ios::clock=mmc_host::f_init;/*设置时钟频率*/mmc_host::mmc_ios::power_mode=MMC_POWER_ON/*设置power状态为正常供电*/mmc_set_ios/*将io相关设置写入Host驱动*/mmc_release_host/*释放Host控制器*/mmc_gpiod_request_cd_irq/*释放Host控制器*/_mmc_detect_change/*Card扫描*/mmc_host::detect_change= 1

/*设置Card检测标志*/mmc_schedule_delayed_work(mmc_host::detect);/*调度工作队列, 调度函数为mmc_rescan*/

3.2 Card API

/*注册/注销MMC Card驱动*/

int mmc_register_driver(struct mmc_driver *);void mmc_unregister_driver(struct mmc_driver *);/*注册/注销SDIO Card驱动*/

int sdio_register_driver(struct sdio_driver *);void sdio_unregister_driver(struct sdio_driver *);

3.3 General API

/*Card检测*/

void mmc_detect_change(struct mmc_host *host, unsigned long delay);

3.4 Command API

cmd0 -mmc_go_idle

cmd1-mmc_send_op_cond

cmd2- mmc_all_send_cid

4. MMC启动

MMC在启动时会进行相应的初始化

mmc_init

mmc_register_bus

bus_register /*注册了mmc总线*/mmc_register_host_class

class_register/*注册'mmc_host'设备类*/sdio_register_bus

bus_register /*注册了sdio总线*/mmc_blk_init

register_blkdev/*注册mmc块设备*/mmc_register_driver

driver_register/*注册mmc card驱动*/

5. MMC扫描

MMC设备的发现通过mmc_rescan函数来实现，通过_mmc_detect_change/mmc_detect_change来触发

mmc_rescan主要流程如下

mmc_rescan

mmc_host::mmc_host_ops::card_event

mmc_host::mmc_bus_ops::detect

mmc_host::mmc_host_ops::get_cd

mmc_rescan_try_freq/*使用不同时钟频率进行初始化*/mmc_power_up/*设备供电*/mmc_hw_reset_for_init/*针对部分eMMC(VCCQ一直为高)*/mmc_host::mmc_host_ops::hw_reset

sdio_reset/*仅针对SDIO设备*/mmc_go_idle/*发送CMD0命令*/mmc_send_if_cond/*仅针对SD设备*/mmc_attach_sdio/*SDIO设备初始化*/mmc_attach_sd/*SD设备初始化*/mmc_attach_mmc/*MMC设备初始化*/mmc_power_off/*当上述设备都不是则停止供电*/

其中SDIO、SD、MMC的初始化流程各不相同

mmc_attach_sdio主要流程如下

/*SDIO Card初始化*/mmc_attach_sdio

mmc_send_io_op_cond/*发送SD_IO_SEND_OP_COND, 获取？？？*/mmc_attach_bus(mmc_sdio_ops)/*将SDIO总线操作集分配给Host*/host->ocr_avail = host->ocr_avail_sdio;/*设置SDIO的OCR*/mmc_select_voltage/*选择合适的电压值*/mmc_sdio_init_card/*识别和初始化SDIO Card*/......

pm_runtime_set_active/*设置Card运行时PM状态为活跃, 仅针对支持MMC_CAP_POWER_OFF_CARD特性的Host*/pm_runtime_enable/*使能Card运行时PM, 仅针对支持MMC_CAP_POWER_OFF_CARD特性的Host*/....../*sdio functions related*/mmc_add_card(mmc_host::mmc_card)/*注册SDIO Card*/sdio_add_func(mmc_host::mmc_card::sdio_func)/*注册SDIO function*/

mmc_attach_sd主要流程如下

/*SD Card初始化*/mmc_attach_sd

mmc_send_app_op_cond/*发送SD_APP_OP_COND, 获取？？？*/mmc_attach_bus(mmc_sd_ops)/*将SD总线操作集分配给Host*/host->ocr_avail = host->ocr_avail_sd;/*设置SD的OCR*/mmc_host_is_spi->mmc_go_idle/*发送CMD0*/mmc_spi_read_ocr/*发送MMC_SPI_READ_OCR, 读取???*/mmc_select_voltage/*选择合适的电压值*/mmc_sd_init_card/*识别和初始化SD Card*/......

mmc_add_card(mmc_host::mmc_card)/*注册SD Card*/

mmc_attach_mmc主要流程如下

/*MMC Card初始化*/mmc_attach_mmc

mmc_send_op_cond/*发送MMC_SEND_OP_COND, 获取？？？*/mmc_attach_bus(mmc_ops)/*将MMC总线操作集分配给Host*/host->ocr_avail = host->ocr_avail_mmc;/*设置MMC的OCR*/mmc_host_is_spi->mmc_spi_read_ocr/*发送MMC_SPI_READ_OCR, 读取???*/mmc_select_voltage/*选择合适的电压值*/mmc_init_card/*识别和初始化MMC Card*/......

mmc_add_card(mmc_host::mmc_card)/*注册MMC Card*/

6. Host驱动

Host驱动的编写主要步骤如下:

1. 通过mmc_alloc_host分配一个mmc_host结构体2. 定义实现mmc_host_ops数据结构, 并赋值给上面的mmc_host::mmc_host_ops成员变量3. 给mmc_host成员变量赋值, 如ocr_avail、caps等成员变量4. 调用mmc_add_host注册该Host

7. Card驱动

对于Memory Card，内核实现了块设备驱动; 对于SDIO设备(比如WiFi), 则需要厂商实现(比如BCM的bcmdhd)

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