一、sdhci core說明 1、sdhci說明 具體參考《host（第一章）——概述》 SDHC：Secure Digital(SD) Host Controller，是指一套sd host控制器的設計標準，其寄存器偏移以及意義都有一定的規範，並且提供了對應的驅動程式，方便vendor進行host ...
一、sdhci core說明
1、sdhci說明
具體參考《host（第一章）——概述》
SDHC：Secure Digital(SD) Host Controller，是指一套sd host控制器的設計標準，其寄存器偏移以及意義都有一定的規範，並且提供了對應的驅動程式，方便vendor進行host controller的開發。
vendor按照這套標準設計host controller之後，可以直接使用sdhci driver來實現host controller的使用，（qcom和samsung都使用了這套標準）。而vendor只需要實現平臺相關的部分、如clock、pinctrl、power等等的部分即可。
關於這個標準，我們可以參考《SDHC_Ver3.00_Final_110225》。
註意，強調一下，這是一種mmc host controller的設計標準，其本質上還是屬於mmc host。並且，其相容mmc type card，而不是說只能使用於sd type card。
2、sdhci core
因為sdhci driver並不是某個特定host的driver，而是提供了一些介面和操作集方法給對應的host driver使用。
因此，我們將sdhci.c的代碼部分稱之為sdhci core用以和host driver區分。
其主要功能如下：
- 為host driver提供分配、釋放sdhci_host的介面
- 為host driver提供註冊、卸載sdhci_host的介面
- 實現sdhci_host和mmc_host的對接（也就是mmc core的對接）
- 實現host關於SDHCI標準的通用操作（sdhci_ops）
- 實現host的通用電源管理操作
註意，clock和pinctrl是由host driver自己管理，sdhci core並不參與。
3、代碼位置
drivers/mmc/host/sdhci.c
drivers/mmc/host/sdhci.h二、數據結構
1、struct sdhci_host
sdhci core將host抽象出struct sdhci_host來進行管理和維護。
數據結構如下：
struct sdhci_host {
/* Data set by hardware interface driver */
const char *hw_name; /* Hardware bus name */ // 名稱
unsigned int quirks; /* Deviations from spec. */ // 癖好，可以理解為硬體sdhci controller和標準sdhci規範不符合的地方。
unsigned int quirks2; /* More deviations from spec. */ // 癖好2，可以理解為硬體sdhci controller和標準sdhci規範不符合的地方。
int irq; /* Device IRQ */ // sdhci的中斷
void __iomem *ioaddr; /* Mapped address */ // sdhci寄存器的基地址
const struct sdhci_ops *ops; /* Low level hw interface */ // 底層硬體的操作介面
struct regulator *vmmc; /* Power regulator (vmmc) */ // sdhci core的LDO
struct regulator *vqmmc; /* Signaling regulator (vccq) */ // 給sdhci io供電的LDO
/* Internal data */
struct mmc_host *mmc; /* MMC structure */ // struct mmc_host，用於註冊到mmc subsystem中
u64 dma_mask; /* custom DMA mask */
spinlock_t lock; /* Mutex */ // 自旋鎖
int flags; /* Host attributes */ // sdhci的一些標識
unsigned int version; /* SDHCI spec. version */ // 當前sdhci的硬體版本
unsigned int max_clk; /* Max possible freq (MHz) */ // 該sdhci支持的最大電壓
unsigned int timeout_clk; /* Timeout freq (KHz) */ // 超時頻率
unsigned int clk_mul; /* Clock Muliplier value */ // 當前倍頻值
unsigned int clock; /* Current clock (MHz) */ // 當前工作頻率
u8 pwr; /* Current voltage */ // 當前工作電壓
bool runtime_suspended; /* Host is runtime suspended */ // 是否處於runtime suspend狀態
struct mmc_request *mrq; /* Current request */ // 當前正在處理的請求
struct mmc_command *cmd; /* Current command */ // 當前的命令請求
struct mmc_data *data; /* Current data request */ // 當前的數據請求
unsigned int data_early:1; /* Data finished before cmd */ // 表示在CMD處理完成前，data已經處理完成
struct sg_mapping_iter sg_miter; /* SG state for PIO */
unsigned int blocks; /* remaining PIO blocks */
int sg_count; /* Mapped sg entries */
u8 *adma_desc; /* ADMA descriptor table */
u8 *align_buffer; /* Bounce buffer */
unsigned int adma_desc_sz; /* ADMA descriptor table size */
unsigned int adma_desc_line_sz; /* ADMA descriptor line size */
unsigned int align_buf_sz; /* Bounce buffer size */
unsigned int align_bytes; /* Alignment bytes (4/8 for 32-bit/64-bit) */
unsigned int adma_max_desc; /* Max ADMA descriptos (max sg segments) */
dma_addr_t adma_addr; /* Mapped ADMA descr. table */
dma_addr_t align_addr; /* Mapped bounce buffer */
struct tasklet_struct card_tasklet; /* Tasklet structures */ // card tasklet，用於處理card的插入或者拔出事件
struct tasklet_struct finish_tasklet; // finsh tasklet，用來通知上層一個請求處理完成（包括出錯的情況）
struct timer_list timer; /* Timer for timeouts */ // 超時定時器鏈表
u32 caps; /* Alternative CAPABILITY_0 */ // 表示該sdhci controller的屬性
u32 caps1; /* Alternative CAPABILITY_1 */ // 表示該sdhci controller的屬性
unsigned int ocr_avail_sdio; /* OCR bit masks */ // 在該sdhci controller上可用的sdio card的ocr值掩碼（代表了其可用電壓）
unsigned int ocr_avail_sd; // 在該sdhci controller上可用的sd card的ocr值掩碼（代表了其可用電壓）
unsigned int ocr_avail_mmc; /// 在該sdhci controller上可用的mmc card的ocr值掩碼（代表了其可用電壓）
/* 以下和mmc的tuning相關 */
wait_queue_head_t buf_ready_int; /* Waitqueue for Buffer Read Ready interrupt */
unsigned int tuning_done; /* Condition flag set when CMD19 succeeds */
unsigned int tuning_count; /* Timer count for re-tuning */
unsigned int tuning_mode; /* Re-tuning mode supported by host */
#define SDHCI_TUNING_MODE_1 0
struct timer_list tuning_timer; /* Timer for tuning */
/* 以下和sdhci的qos相關 */
struct sdhci_host_qos host_qos[SDHCI_QOS_MAX_POLICY];
enum sdhci_host_qos_policy last_qos_policy;
bool host_use_default_qos;
unsigned int pm_qos_timeout_us; /* timeout for PM QoS request */
struct device_attribute pm_qos_tout;
struct delayed_work pm_qos_work;
struct sdhci_next next_data;
ktime_t data_start_time;
struct mutex ios_mutex;
enum sdhci_power_policy power_policy;
bool irq_enabled; /* host irq status flag */ // 表示中斷是否使能？
bool async_int_supp; /* async support to rxv int, when clks are off */
bool disable_sdio_irq_deferred; /* status of disabling sdio irq */
u32 auto_cmd_err_sts;
struct ratelimit_state dbg_dump_rs;
int reset_wa_applied; /* reset workaround status */
ktime_t reset_wa_t; /* time when the reset workaround is applied */
int reset_wa_cnt; /* total number of times workaround is used */
unsigned long private[0] ____cacheline_aligned; // 私有數據指針
};- 癖好1（sdhci_host->quirks）各個位意義如下：
/* Controller doesn't honor resets unless we touch the clock register */
#define SDHCI_QUIRK_CLOCK_BEFORE_RESET (1<<0)
/* Controller has bad caps bits, but really supports DMA */
#define SDHCI_QUIRK_FORCE_DMA (1<<1)
/* Controller doesn't like to be reset when there is no card inserted. */
#define SDHCI_QUIRK_NO_CARD_NO_RESET (1<<2)
/* Controller doesn't like clearing the power reg before a change */
#define SDHCI_QUIRK_SINGLE_POWER_WRITE (1<<3)
/* Controller has flaky internal state so reset it on each ios change */
#define SDHCI_QUIRK_RESET_CMD_DATA_ON_IOS (1<<4)
/* Controller has an unusable DMA engine */
#define SDHCI_QUIRK_BROKEN_DMA (1<<5)
/* Controller has an unusable ADMA engine */
#define SDHCI_QUIRK_BROKEN_ADMA (1<<6)
/* Controller can only DMA from 32-bit aligned addresses */
#define SDHCI_QUIRK_32BIT_DMA_ADDR (1<<7)
/* Controller can only DMA chunk sizes that are a multiple of 32 bits */
#define SDHCI_QUIRK_32BIT_DMA_SIZE (1<<8)
/* Controller can only ADMA chunks that are a multiple of 32 bits */
#define SDHCI_QUIRK_32BIT_ADMA_SIZE (1<<9)
/* Controller needs to be reset after each request to stay stable */
#define SDHCI_QUIRK_RESET_AFTER_REQUEST (1<<10)
/* Controller needs voltage and power writes to happen separately */
#define SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER (1<<11)
/* Controller provides an incorrect timeout value for transfers */
#define SDHCI_QUIRK_BROKEN_TIMEOUT_VAL (1<<12)
/* Controller has an issue with buffer bits for small transfers */
#define SDHCI_QUIRK_BROKEN_SMALL_PIO (1<<13)
/* Controller does not provide transfer-complete interrupt when not busy */
#define SDHCI_QUIRK_NO_BUSY_IRQ (1<<14)
/* Controller has unreliable card detection */
#define SDHCI_QUIRK_BROKEN_CARD_DETECTION (1<<15)
/* Controller reports inverted write-protect state */
#define SDHCI_QUIRK_INVERTED_WRITE_PROTECT (1<<16)
/* Controller has nonstandard clock management */
#define SDHCI_QUIRK_NONSTANDARD_CLOCK (1<<17)
/* Controller does not like fast PIO transfers */
#define SDHCI_QUIRK_PIO_NEEDS_DELAY (1<<18)
/* Controller losing signal/interrupt enable states after reset */
#define SDHCI_QUIRK_RESTORE_IRQS_AFTER_RESET (1<<19)
/* Controller has to be forced to use block size of 2048 bytes */
#define SDHCI_QUIRK_FORCE_BLK_SZ_2048 (1<<20)
/* Controller cannot do multi-block transfers */
#define SDHCI_QUIRK_NO_MULTIBLOCK (1<<21)
/* Controller can only handle 1-bit data transfers */
#define SDHCI_QUIRK_FORCE_1_BIT_DATA (1<<22)
/* Controller needs 10ms delay between applying power and clock */
#define SDHCI_QUIRK_DELAY_AFTER_POWER (1<<23)
/* Controller uses SDCLK instead of TMCLK for data timeouts */
#define SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK (1<<24)
/* Controller reports wrong base clock capability */
#define SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN (1<<25)
/* Controller cannot support End Attribute in NOP ADMA descriptor */
#define SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC (1<<26)
/* Controller is missing device caps. Use caps provided by host */
#define SDHCI_QUIRK_MISSING_CAPS (1<<27)
/* Controller uses Auto CMD12 command to stop the transfer */
#define SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12 (1<<28)
/* Controller doesn't have HISPD bit field in HI-SPEED SD card */
#define SDHCI_QUIRK_NO_HISPD_BIT (1<<29)
/* Controller treats ADMA descriptors with length 0000h incorrectly */
#define SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC (1<<30)
/* The read-only detection via SDHCI_PRESENT_STATE register is unstable */
#define SDHCI_QUIRK_UNSTABLE_RO_DETECT (1<<31)- 癖好2（sdhci_host->quirks2）各個位意義如下：
#define SDHCI_QUIRK2_HOST_OFF_CARD_ON (1<<0)
#define SDHCI_QUIRK2_HOST_NO_CMD23 (1<<1)
/* The system physically doesn't support 1.8v, even if the host does */
#define SDHCI_QUIRK2_NO_1_8_V (1<<2)
#define SDHCI_QUIRK2_PRESET_VALUE_BROKEN (1<<3)
/*
* Read Transfer Active/ Write Transfer Active may be not
* de-asserted after end of transaction. Issue reset for DAT line.
*/
#define SDHCI_QUIRK2_RDWR_TX_ACTIVE_EOT (1<<4)
/*
* Slow interrupt clearance at 400KHz may cause
* host controller driver interrupt handler to
* be called twice.
*/
#define SDHCI_QUIRK2_SLOW_INT_CLR (1<<5)
/*
* If the base clock can be scalable, then there should be no further
* clock dividing as the input clock itself will be scaled down to
* required frequency.
*/
#define SDHCI_QUIRK2_ALWAYS_USE_BASE_CLOCK (1<<6)
/*
* Dont use the max_discard_to in sdhci driver so that the maximum discard
* unit gets picked by the mmc queue. Otherwise, it takes a long time for
* secure discard kind of operations to complete.
*/
#define SDHCI_QUIRK2_USE_MAX_DISCARD_SIZE (1<<7)
/*
* Ignore data timeout error for R1B commands as there will be no
* data associated and the busy timeout value for these commands
* could be lager than the maximum timeout value that controller
* can handle.
*/
#define SDHCI_QUIRK2_IGNORE_DATATOUT_FOR_R1BCMD (1<<8)
/*
* The preset value registers are not properly initialized by
* some hardware and hence preset value must not be enabled for
* such controllers.
*/
#define SDHCI_QUIRK2_BROKEN_PRESET_VALUE (1<<9)
/*
* Some controllers define the usage of 0xF in data timeout counter
* register (0x2E) which is actually a reserved bit as per
* specification.
*/
#define SDHCI_QUIRK2_USE_RESERVED_MAX_TIMEOUT (1<<10)
/*
* This is applicable for controllers that advertize timeout clock
* value in capabilities register (bit 5-0) as just 50MHz whereas the
* base clock frequency is 200MHz. So, the controller internally
* multiplies the value in timeout control register by 4 with the
* assumption that driver always uses fixed timeout clock value from
* capabilities register to calculate the timeout. But when the driver
* uses SDHCI_QUIRK2_ALWAYS_USE_BASE_CLOCK base clock frequency is directly
* controller by driver and it's rate varies upto max. 200MHz. This new quirk
* will be used in such cases to avoid controller mulplication when timeout is
* calculated based on the base clock.
*/
#define SDHCI_QUIRK2_DIVIDE_TOUT_BY_4 (1 << 11)
/*
* Some SDHC controllers are unable to handle data-end bit error in
* 1-bit mode of SDIO.
*/
#define SDHCI_QUIRK2_IGN_DATA_END_BIT_ERROR (1<<12)
/*
* Some SDHC controllers do not require data buffers alignment, skip
* the bounce buffer logic when preparing data
*/
#define SDHCI_QUIRK2_ADMA_SKIP_DATA_ALIGNMENT (1<<13)
/* Some controllers doesn't have have any LED control */
#define SDHCI_QUIRK2_BROKEN_LED_CONTROL (1 << 14)
/* Use reset workaround in case sdhci reset timeouts */
#define SDHCI_QUIRK2_USE_RESET_WORKAROUND (1 << 15)- sdhci host的一些標識（sdhci_host->flags）如下：
#define SDHCI_USE_SDMA (1<<0) /* Host is SDMA capable */
#define SDHCI_USE_ADMA (1<<1) /* Host is ADMA capable */
#define SDHCI_REQ_USE_DMA (1<<2) /* Use DMA for this req. */
#define SDHCI_DEVICE_DEAD (1<<3) /* Device unresponsive */
#define SDHCI_SDR50_NEEDS_TUNING (1<<4) /* SDR50 needs tuning */
#define SDHCI_NEEDS_RETUNING (1<<5) /* Host needs retuning */
#define SDHCI_AUTO_CMD12 (1<<6) /* Auto CMD12 support */
#define SDHCI_AUTO_CMD23 (1<<7) /* Auto CMD23 support */
#define SDHCI_PV_ENABLED (1<<8) /* Preset value enabled */
#define SDHCI_SDIO_IRQ_ENABLED (1<<9) /* SDIO irq enabled */
#define SDHCI_HS200_NEEDS_TUNING (1<<10) /* HS200 needs tuning */
#define SDHCI_USING_RETUNING_TIMER (1<<11) /* Host is using a retuning timer for the card */
#define SDHCI_HS400_NEEDS_TUNING (1<<12) /* HS400 needs tuning */
#define SDHCI_USE_ADMA_64BIT (1<<13)/* Host is 64-bit ADMA capable */2、struct sdhci_ops結構體
sdhci core只是提供了一些介面和符合mmc core的操作集方法給對應的host driver使用。由於各個host的硬體有所差異，所以實際和硬體交互的驅動部分還是在host driver中實現。
所以sdhci core要求host提供標準的訪問硬體的一些方法。而這些方法就被定義在了struct sdhci_ops結構體內部。
結構體如下：
struct sdhci_ops {
#ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
// 表示host另外提供了一套訪問寄存器的方法，沒有定義的話，則說明使用通用的讀寫寄存器的方法
u32 (*read_l)(struct sdhci_host *host, int reg);
u16 (*read_w)(struct sdhci_host *host, int reg);
u8 (*read_b)(struct sdhci_host *host, int reg);
void (*write_l)(struct sdhci_host *host, u32 val, int reg);
void (*write_w)(struct sdhci_host *host, u16 val, int reg);
void (*write_b)(struct sdhci_host *host, u8 val, int reg);
#endif
void (*set_clock)(struct sdhci_host *host, unsigned int clock); // 設置時鐘頻率
int (*enable_dma)(struct sdhci_host *host); // 使能DMA
unsigned int (*get_max_clock)(struct sdhci_host *host); // 獲取支持的最大時鐘頻率
unsigned int (*get_min_clock)(struct sdhci_host *host); // 獲取支持的最小時鐘頻率
unsigned int (*get_timeout_clock)(struct sdhci_host *host);
int (*platform_bus_width)(struct sdhci_host *host, int width);
void (*platform_send_init_74_clocks)(struct sdhci_host *host,
u8 power_mode);
unsigned int (*get_ro)(struct sdhci_host *host); // 獲取
void (*platform_reset_enter)(struct sdhci_host *host, u8 mask); // 進入平臺複位的方法
void (*platform_reset_exit)(struct sdhci_host *host, u8 mask); // 退出平臺複位的方法
int (*set_uhs_signaling)(struct sdhci_host *host, unsigned int uhs); // 設置uhs方式
void (*hw_reset)(struct sdhci_host *host); // 硬體複位的方法
void (*platform_suspend)(struct sdhci_host *host); // 平臺host的suspend方法
void (*platform_resume)(struct sdhci_host *host); // 平臺host的resume方法
void (*adma_workaround)(struct sdhci_host *host, u32 intmask);
void (*platform_init)(struct sdhci_host *host); // 平臺host的初始化方法
void (*check_power_status)(struct sdhci_host *host, u32 req_type); // 檢測匯流排的電源狀態
#define REQ_BUS_OFF (1 << 0)
#define REQ_BUS_ON (1 << 1)
#define REQ_IO_LOW (1 << 2)
#define REQ_IO_HIGH (1 << 3)
int (*execute_tuning)(struct sdhci_host *host, u32 opcode); // 執行tuning操作的的方法
void (*toggle_cdr)(struct sdhci_host *host, bool enable);
unsigned int (*get_max_segments)(void);
void (*platform_bus_voting)(struct sdhci_host *host, u32 enable); // 平臺匯流排投票的方法
void (*disable_data_xfer)(struct sdhci_host *host);
void (*dump_vendor_regs)(struct sdhci_host *host);
int (*config_auto_tuning_cmd)(struct sdhci_host *host,
bool enable,
u32 type);
int (*enable_controller_clock)(struct sdhci_host *host);
void (*reset_workaround)(struct sdhci_host *host, u32 enable);
};這個結構體也就是host driver要實現的核心內容。
3、struct mmc_host_ops sdhci_ops
註意：這裡的sdhci_ops是一個變數名，和上述的struct sdhci_ops不是同一個概念。搞不懂為什麼這麼命名，容易混淆。
sdhci core使用sdhci_ops作為sdhci host抽象出來的mmc host的操作集，所以其是一個struct mmc_host_ops結構體。
後續mmc core關於這個host的操作也都是基於這個操作集上實現的，包括使能host（enable方法）、禁用host（disable方法）、發送請求（request方法）。
具體參考《mmc core》系列。
具體實現如下，具體意義參考《mmc core（第二章）——數據結構和巨集定義說明》：
static const struct mmc_host_ops sdhci_ops = {
// post_req和pre_req是為了實現非同步請求處理而設置的
// 非同步請求處理就是指，當另外一個非同步請求還沒有處理完成的時候，可以先準備另外一個非同步請求而不必等待
// 具體參考《mmc core主模塊》
.pre_req = sdhci_pre_req,
.post_req = sdhci_post_req,
.request = sdhci_request, // host處理mmc請求的方法，在mmc_start_request中會調用
.set_ios = sdhci_set_ios, // 設置host的匯流排的io setting
.get_cd = sdhci_get_cd, // 檢測host的卡槽中card的插入狀態
.get_ro = sdhci_get_ro, // 獲取host上的card的讀寫屬性
.hw_reset = sdhci_hw_reset, // 硬體複位
.enable_sdio_irq = sdhci_enable_sdio_irq,
.start_signal_voltage_switch = sdhci_start_signal_voltage_switch, // 切換信號電壓的方法
.execute_tuning = sdhci_execute_tuning, // 執行tuning操作，為card選擇一個合適的採樣點
.card_event = sdhci_card_event,
.card_busy = sdhci_card_busy, // 用於檢測card是否處於busy狀態
.enable = sdhci_enable, // 使能host，當host被占用時（第一次調用mmc_claim_host）調用
.disable = sdhci_disable, // 禁用host，當host被釋放時（第一次調用mmc_release_host）調用
.stop_request = sdhci_stop_request, // 停止請求處理的方法
.get_xfer_remain = sdhci_get_xfer_remain,
.notify_load = sdhci_notify_load,
};三、API總覽
1、sdhci_host分配和釋放相關
- sdhci_alloc_host & sdhci_free_host
由底層host driver調用。
sdhci_alloc_host為host driver分配一個sdhci_host和mmc_host，並實現其初始化，以及sdhci_host和mmc_host的關聯。
sdhci_free_host則是用來釋放一個sdhci_host。
原型：struct sdhci_host *sdhci_alloc_host(struct device *dev, size_t priv_size)
參數說明：struct device *dev——》對應host的device結構體
size_t priv_size——》要分配的sdhci_host的私有數據的長度，一般是平臺自己定製的host的長度。
原型：void sdhci_free_host(struct sdhci_host *host)2、sdhci_host的註冊和卸載相關
- sdhci_add_host & sdhci_remove_host
由底層host driver調用。
sdhci_add_host用於向sdhci core註冊一個sdhci_host。會根據sdhci的寄存器以及部分標識設置其mmc_host，最終將mmc_host註冊到mmc core中。
因此，在調用sdhci_add_host之前，必須準備好sdhci的所有硬體環境。
sdhci_free_host則用於從sdhci core中卸載一個sdhci_host，對應的mmc_host也會從mmc core中被卸載。
原型：int sdhci_add_host(struct sdhci_host *host)；
原型：void sdhci_remove_host(struct sdhci_host *host, int dead)；四、介面代碼說明
1、sdhci_alloc_host
struct sdhci_host *sdhci_alloc_host(struct device *dev,
size_t priv_size)
{
struct mmc_host *mmc;
struct sdhci_host *host;
WARN_ON(dev == NULL);
/* 實現mmc_host和sdhci_host的分配 */
mmc = mmc_alloc_host(sizeof(struct sdhci_host) + priv_size, dev); // 分配一個struct mmc_host
// 分配mmc_host的同時也分配了sizeof(struct sdhci_host) + priv_size的私有數據空間，這部分就是作為sdhci_host及其私有數據使用的。
// 具體參考《mmc core——host模塊說明》
if (!mmc)
return ERR_PTR(-ENOMEM);
/* 實現mmc_host和sdhci_host的關聯操作 */
host = mmc_priv(mmc); // 將sdhci_host作為mmc_host的私有數據，mmc_host->private = sdhci_host
host->mmc = mmc; // 關聯sdhci_host和mmc_host，sdhci_host->mmc = mmc_host
/* sdhci_host的鎖的初始化工作 */
spin_lock_init(&host->lock); // 初始化sdhci_host 的占有鎖
mutex_init(&host->ios_mutex); // 初始化sdhci_host 設置io setting的互斥鎖
return host; // 將struct sdhci_host 返回
}綜上，
mmc_host->private = sdhci_host
sdhci_host->mmc = mmc_host2、sdhci_add_host
（0）底層傳上來的sdhci_host中應該包含什麼信息
- sdhci的寄存器的映射過後的基地址（sdhci_host->ioaddr）
- sdhci的癖好quirks、quirks2（sdhci_host->quirks，sdhci_host->quirks2）
- sdhci的中斷號（sdhci_host->irq）
- host提供給sdhci core用來操作硬體的操作集（sdhci_host->ops）
（1）主要完成工作如下：
- sdhci host複位
調用sdhci_reset
- 讀取該host的sdhci的信息（從sdhci相關寄存器中讀取）並設置sdhci_host相關成員
- 版本（sdhci_host->version） : 從SDHCI_HOST_VERSION寄存器中讀取
- 支持的屬性 : 從SDHCI_CAPABILITIES、SDHCI_CAPABILITIES_1寄存器中讀取
- 標識（sdhci_host->version） : 根據sdhci_host->quirks和quirks2來設置
- 支持的最大頻率和倍頻（sdhci_host->max_clk & sdhci_host->clk_mul）
對應SDHCI_CAPABILITIES寄存器中的SDHCI_CLOCK_BASE_SHIFT位
對應SDHCI_CAPABILITIES寄存器中的SDHCI_CLOCK_MUL_SHIFT位 - sdhci使用的regulator（sdhci_host->vqmmc）
從節點中的命名為”vmmc”的regulator屬性中獲取 - card插入狀態發生變化時調用的tasklet（sdhci_host->card_tasklet）
設置為sdhci_tasklet_card - 請求處理完成時調用的tasklet（sdhci_host->finish_tasklet）
設置為sdhci_tasklet_finish - 請求的處理超時定時器（sdhci_host->timer）
設置為sdhci_timeout_timer - qos處理的工作（sdhci_host->pm_qos_work）
設置為sdhci_pm_qos_remove_work
- 設置mmc_host的相關成員
- 操作集（mmc_host->ops）
設置為sdhci_ops，上面已經說明過了 - 最大頻率（mmc_host->f_max）
用sdhci_host->max_clk的值來設置 - host的屬性（mmc_host->caps & mmc_host->caps2）
通過sdhci_host->quirks和quirks2、以及SDHCI_CAPABILITIES、SDHCI_CAPABILITIES_1寄存器中的屬性進行設置 - 各個電壓下的最大電流值（mmc_host->max_current_330 & mmc_host->max_current_300 & mmc_host->max_current_180）
從SDHCI_MAX_CURRENT寄存器中讀取 - 可用電壓（mmc->ocr_avail & mmc->ocr_avail_sdio & mmc->ocr_avail_sd & mmc->ocr_avail_mmc）
從SDHCI_CAPABILITIES寄存器中的SDHCI_CAN_VDD_330、SDHCI_CAN_VDD_300、SDHCI_CAN_VDD_180位獲取 - 一些塊和段size的設置
- 操作集（mmc_host->ops）
中斷的註冊
將sdhci_host的中斷處理函數註冊為sdhci_irq- sdhci host初始化
調用sdhci_init - 註冊mmc_host到mmc core中
調用mmc_add_host 使能card插入狀態的檢測
調用sdhci_enable_card_detection
（2）代碼如下：
int sdhci_add_host(struct sdhci_host *host)
{
// 以下變數要註意區分
// host是指要註冊的sdhci host
// mmc是指要註冊到mmc subsystem的host，封裝在sdhci host中
struct mmc_host *mmc;
u32 caps[2] = {0, 0};
u32 max_current_caps;
unsigned int ocr_avail;
int ret;
WARN_ON(host == NULL);
if (host == NULL)
return -EINVAL;
mmc = host->mmc; // 獲取struct mmc_host
/* 執行複位操作 */
sdhci_reset(host, SDHCI_RESET_ALL);
// 執行reset操作，會調用到sdhci_host->ops->platform_reset_enter，msm並沒有實現這個方法
/********************************* 獲取sdhci信息並設置sdhci_host的相應成員***********************/
/* 獲取sdhci controller版本號 */
host->version = sdhci_readw(host, SDHCI_HOST_VERSION);
host->version = (host->version & SDHCI_SPEC_VER_MASK) >> SDHCI_SPEC_VER_SHIFT;
// 獲取sdhci host的硬體版本號
/* 獲取sdhci controller支持的屬性 */
caps[0] = (host->quirks & SDHCI_QUIRK_MISSING_CAPS) ? host->caps : sdhci_readl(host, SDHCI_CAPABILITIES);
// SDHCI_QUIRK_MISSING_CAPS：Controller is missing device caps. Use caps provided by host
// sdhci控制器沒有devices屬性的話，由底層host提供，否則，從sdhci controller的SDHCI_CAPABILITIES讀取屬性
if (host->version >= SDHCI_SPEC_300)
caps[1] = (host->quirks & SDHCI_QUIRK_MISSING_CAPS) ?host->caps1 : sdhci_readl(host, SDHCI_CAPABILITIES_1);
// 從sdhci controller的SDHCI_CAPABILITIES_1讀取屬性
/* 設置sdhci_host->flags中和DMA相關的flag */
if (host->quirks & SDHCI_QUIRK_FORCE_DMA)
host->flags |= SDHCI_USE_SDMA;
else if (!(caps[0] & SDHCI_CAN_DO_SDMA))
DBG("Controller doesn't have SDMA capability\n");
else
host->flags |= SDHCI_USE_SDMA;
// SDHCI_QUIRK_FORCE_DMA : Controller has bad caps bits, but really supports DMA
// 設置sdhci_host->flags中的SDHCI_USE_SDMA標識
//............................
if (host->flags & SDHCI_USE_ADMA) {
// sdhci_host ->adma_max_desc
// sdhci_host ->adma_desc_line_sz
// sdhci_host ->align_bytes
// sdhci_host ->adma_desc_sz
// sdhci_host ->align_buf_sz
// sdhci_host ->adma_desc
// sdhci_host ->align_buffer
}
host->next_data.cookie = 1;
/* 獲取sdhci controller支持的最大頻率以及倍頻 */
if (host->version >= SDHCI_SPEC_300)
host->max_clk = (caps[0] & SDHCI_CLOCK_V3_BASE_MASK)
>> SDHCI_CLOCK_BASE_SHIFT; // 從sdhci controller的SDHCI_CLOCK_V3_BASE_MASK讀取最大clock（單位是MHZ）
else
host->max_clk = (caps[0] & SDHCI_CLOCK_BASE_MASK)
>> SDHCI_CLOCK_BASE_SHIFT;
host->max_clk *= 1000000;（轉化為hz）
// 設置sdhci_host->max_clk
sdhci_update_power_policy(host, SDHCI_PERFORMANCE_MODE_INIT);
// 設置sdhci_host->power_policy為SDHCI_PERFORMANCE_MODE_INIT
if (host->max_clk == 0 || host->quirks & SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN) {
host->max_clk = host->ops->get_max_clock(host); // 調用sdhci_host->ops->get_max_clock獲得最大時鐘
}
host->clk_mul = (caps[1] & SDHCI_CLOCK_MUL_MASK) >> SDHCI_CLOCK_MUL_SHIFT;
if (host->clk_mul)
host->clk_mul += 1;
// 設置sdhci_host->clk_mul，clock的倍頻實行
/*************************** 以下對mmc_host和sdhci_host進行設置操作 ***************************/
/* 以下設置mmc_host，ops、f_max、f_min */
mmc->ops = &sdhci_ops; // 設置mmc_host的操作集為sdhci_ops
mmc->f_max = host->max_clk; // 設置最大時鐘頻率mmc_host->f_max
if (host->ops->get_min_clock)
mmc->f_min = host->ops->get_min_clock(host); // 調用sdhci_host->ops->get_min_clock獲得最小時鐘頻率mmc_host->f_min
host->timeout_clk = (caps[0] & SDHCI_TIMEOUT_CLK_MASK) >> SDHCI_TIMEOUT_CLK_SHIFT;
// 從sdhci controller的SDHCI_TIMEOUT_CLK_MASK讀取最大timeout
// 設置到sdhci_host->timeout_clk
if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
host->timeout_clk = mmc->f_max / 1000;
if (!(host->quirks2 & SDHCI_QUIRK2_USE_MAX_DISCARD_SIZE))
mmc->max_discard_to = (1 << 27) / host->timeout_clk;
// 設置mmc_host->max_discard_to
/* 設置mmc_host->caps，也就是屬性 */
mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA))
mmc->caps |= MMC_CAP_4_BIT_DATA;
if (host->quirks2 & SDHCI_QUIRK2_HOST_NO_CMD23)
mmc->caps &= ~MMC_CAP_CMD23;
if (caps[0] & SDHCI_CAN_DO_HISPD)
mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED;
if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) &&
!(host->mmc->caps & MMC_CAP_NONREMOVABLE) &&
(mmc_gpio_get_cd(host->mmc) < 0) &&
!(host->mmc->caps2 & MMC_CAP2_NONHOTPLUG))
mmc->caps |= MMC_CAP_NEEDS_POLL;
/* 獲取vqmmc regulater並使能 */
/* If vqmmc regulator and no 1.8V signalling, then there's no UHS */
host->vqmmc = regulator_get(mmc_dev(mmc), "vqmmc");
if (IS_ERR_OR_NULL(host->vqmmc)) {
....
} else {
ret = regulator_enable(host->vqmmc);
if (!regulator_is_supported_voltage(host->vqmmc, 1700000,1950000))
caps[1] &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 | SDHCI_SUPPORT_DDR50);
}
if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V)
caps[1] &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 | SDHCI_SUPPORT_DDR50);
/* 設置mmc_host->caps和傳輸模式相關的屬性 */
/* Any UHS-I mode in caps implies SDR12 and SDR25 support. */
if (caps[1] & (SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
SDHCI_SUPPORT_DDR50))
mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
/* SDR104 supports also implies SDR50 support */
if (caps[1] & SDHCI_SUPPORT_SDR104)
mmc->caps |= MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_SDR50;
else if (caps[1] & SDHCI_SUPPORT_SDR50)
mmc->caps |= MMC_CAP_UHS_SDR50;
if (caps[1] & SDHCI_SUPPORT_DDR50)
mmc->caps |= MMC_CAP_UHS_DDR50;
/* 設置sdhci_host->flags中和tuning相關的flag */
/* Does the host need tuning for SDR50? */
if (caps[1] & SDHCI_USE_SDR50_TUNING)
host->flags |= SDHCI_SDR50_NEEDS_TUNING;
/* Does the host need tuning for HS200? */
if (mmc->caps2 & MMC_CAP2_HS200)
host->flags |= SDHCI_HS200_NEEDS_TUNING;
/* Does the host need tuning for HS400? */
if (mmc->caps2 & MMC_CAP2_HS400)
host->flags |= SDHCI_HS400_NEEDS_TUNING;
/* 設置mmc_host->caps和驅動類型相關的屬性 */
/* Driver Type(s) (A, C, D) supported by the host */
if (caps[1] & SDHCI_DRIVER_TYPE_A)
mmc->caps |= MMC_CAP_DRIVER_TYPE_A;
if (caps[1] & SDHCI_DRIVER_TYPE_C)
mmc->caps |= MMC_CAP_DRIVER_TYPE_C;
if (caps[1] & SDHCI_DRIVER_TYPE_D)
mmc->caps |= MMC_CAP_DRIVER_TYPE_D;
/* 獲取sdhci controller的tuning計數（tuning_count 、tuning_mode ）*/
host->tuning_count = (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
SDHCI_RETUNING_TIMER_COUNT_SHIFT;
if (host->tuning_count)
host->tuning_count = 1 << (host->tuning_count - 1);
host->tuning_mode = (caps[1] & SDHCI_RETUNING_MODE_MASK) >> SDHCI_RETUNING_MODE_SHIFT;
ocr_avail = 0;
/* 獲取vmmc regulater，設置caps[0]支持的電壓值 */
host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
#ifdef CONFIG_REGULATOR
/*
* Voltage range check makes sense only if regulator reports
* any voltage value.
*/
if (host->vmmc && regulator_get_voltage(host->vmmc) > 0) {
ret = regulator_is_supported_voltage(host->vmmc, 2700000,
3600000);
if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_330)))
caps[0] &= ~SDHCI_CAN_VDD_330;
if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_300)))
caps[0] &= ~SDHCI_CAN_VDD_300;
ret = regulator_is_supported_voltage(host->vmmc, 1700000,
1950000);
if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_180)))
caps[0] &= ~SDHCI_CAN_VDD_180;
}
#endif /* CONFIG_REGULATOR */
/* 設置各個電壓下的最大電流值（max_current_330、max_current_330 、max_current_180 ）*/
/* 設置可用電壓域 */
max_current_caps = sdhci_readl(host, SDHCI_MAX_CURRENT);
if (!max_current_caps && host->vmmc) {
u32 curr = regulator_get_current_limit(host->vmmc);
//....................
}
if (caps[0] & SDHCI_CAN_VDD_330) {
ocr_avail |= MMC_VDD_32_33 | MMC_VDD_33_34;
mmc->max_current_330 = ((max_current_caps &
SDHCI_MAX_CURRENT_330_MASK) >>
SDHCI_MAX_CURRENT_330_SHIFT) *
SDHCI_MAX_CURRENT_MULTIPLIER;
}
//.........
mmc->ocr_avail = ocr_avail;
mmc->ocr_avail_sdio = ocr_avail;
// ......
/*********************************** sdhci的初始化工作**************************************/
/* 初始化sdhci工作過程中會使用到的tasklet */
tasklet_init(&host->card_tasklet, sdhci_tasklet_card, (unsigned long)host); // host上發生card插入或者拔出時調用
tasklet_init(&host->finish_tasklet, sdhci_tasklet_finish, (unsigned long)host); // 完成一個request時調用
setup_timer(&host->timer, sdhci_timeout_timer, (unsigned long)host); // command的超時定時器
/* 初始化qos處理的工作 */
INIT_DELAYED_WORK(&host->pm_qos_work, sdhci_pm_qos_remove_work);
/* 中斷註冊和使能 */
ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,mmc_hostname(mmc), host);
host->irq_enabled = true;
/* 對該sdhci controller進行初始化 */
sdhci_init(host, 0);
mmiowb();
/* sdhci關於qos的請求和操作的設置 */
if (host->host_qos[SDHCI_QOS_READ_WRITE].cpu_dma_latency_us) {
// .........
}
/*********************************** 將mmc_host註冊到mmc subsystem中 *******************************/
mmc_add_host(mmc);
/*********************************** 開始使能sdhci和並且開始檢測card狀態******************************/
sdhci_enable_card_detection(host);
return 0;
}重點關註如下幾個部分：
（1）sdhci_reset(host, SDHCI_RESET_ALL);
（2）mmc->ops = &sdhci_ops; // 設置mmc_host的操作集為sdhci_ops
（3）host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
（4）tasklet_init(&host->card_tasklet, sdhci_tasklet_card, (unsigned long)host); // host上發生card插入或者拔出時調用
（5）tasklet_init(&host->finish_tasklet, sdhci_tasklet_finish, (unsigned long)host); // 完成一個request時調用的tasklet
（6）ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,mmc_hostname(mmc), host);
（7）sdhci_init(host, 0); // 軟初始化host
（8）sdhci_enable_card_detection(host); // 開始使能card插入狀態的檢測五、sdhci core內部代碼簡單說明
1、sdhci_reset & sdhci_init & sdhci_enable_card_detection
- sdhci_reset
由sdhci core內部調用，用於複位host。 - sdhci_init
由sdhci core內部調用，用於初始化host - sdhci_enable_card_detection
由sdhci core內部調用，使能card插入狀態的檢測，主要是設置SDHCI_INT_ENABLE、SDHCI_SIGNAL_ENABLE寄存器
static irqreturn_t sdhci_irq(int irq, void *dev_id)
{
irqreturn_t result;
struct sdhci_host *host = dev_id;
u32 intmask, unexpected = 0;
int cardint = 0, max_loops = 16;
spin_lock(&host->lock);
/* 從SDHCI_INT_STATUS寄存器中讀取中斷狀態 */
intmask = sdhci_readl(host, SDHCI_INT_STATUS); // 從SDHCI_INT_STATUS寄存器中讀取中斷狀態
/* 確認是否有中斷產生 */
if (!intmask || intmask == 0xffffffff) {
result = IRQ_NONE;
goto out;
}
again:
DBG("*** %s got interrupt: 0x%08x\n",
mmc_hostname(host->mmc), intmask);
/* 以下是對card插入或者拔出的中斷進行處理 */
if (intmask & (SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE)) {
u32 present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
SDHCI_CARD_PRESENT;
sdhci_mask_irqs(host, present ? SDHCI_INT_CARD_INSERT :
SDHCI_INT_CARD_REMOVE);
sdhci_unmask_irqs(host, present ? SDHCI_INT_CARD_REMOVE :
SDHCI_INT_CARD_INSERT);
sdhci_writel(host, intmask & (SDHCI_INT_CARD_INSERT |
SDHCI_INT_CARD_REMOVE), SDHCI_INT_STATUS); // 重置這兩個中斷位
intmask &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE);
tasklet_schedule(&host->card_tasklet); // 執行host->card_tasklet，也就是sdhci_tasklet_card進行處理，後面說明
}
/* 以下是sdhci處理命令產生的中斷進行處理，不一定是出錯 */
if (intmask & SDHCI_INT_CMD_MASK) {
if (intmask & SDHCI_INT_AUTO_CMD_ERR)
host->auto_cmd_err_sts = sdhci_readw(host,
SDHCI_AUTO_CMD_ERR);
sdhci_writel(host, intmask & SDHCI_INT_CMD_MASK,
SDHCI_INT_STATUS);
if ((host->quirks2 & SDHCI_QUIRK2_SLOW_INT_CLR) &&
(host->clock <= 400000))
udelay(40);
sdhci_cmd_irq(host, intmask & SDHCI_INT_CMD_MASK); // 在sdhci_cmd_irq中會執行host->finish_tasklet, 也就是sdhci_tasklet_finish來通知上層。後面說明。
}
/* 以下是sdhci處理數據產生的中斷進行處理，不一定是出錯 */
if (intmask & SDHCI_INT_DATA_MASK) {
sdhci_writel(host, intmask & SDHCI_INT_DATA_MASK,
SDHCI_INT_STATUS);
if ((host->quirks2 & SDHCI_QUIRK2_SLOW_INT_CLR) &&
(host->clock <= 400000))
udelay(40);
sdhci_data_irq(host, intmask & SDHCI_INT_DATA_MASK); // 在sdhci_data_irq中會執行host->finish_tasklet, 也就是sdhci_tasklet_finish來通知上層。
}
intmask &= ~(SDHCI_INT_CMD_MASK | SDHCI_INT_DATA_MASK);
intmask &= ~SDHCI_INT_ERROR;
/* 以下是對匯流排電源狀態發生變化的中斷的處理 */
if (intmask & SDHCI_INT_BUS_POWER) {
pr_err("%s: Card is consuming too much power!\n",
mmc_hostname(host->mmc));
sdhci_writel(host, SDHCI_INT_BUS_POWER, SDHCI_INT_STATUS);
}
intmask &= ~SDHCI_INT_BUS_POWER;
if (intmask & SDHCI_INT_CARD_INT)
cardint = 1;
intmask &= ~SDHCI_INT_CARD_INT;
if (intmask) {
unexpected |= intmask;
sdhci_writel(host, intmask, SDHCI_INT_STATUS);
}
result = IRQ_HANDLED;
/* 可能不止有其他事件導致中斷的產生，重覆檢測 */
intmask = sdhci_readl(host, SDHCI_INT_STATUS);
if (intmask && --max_loops)
goto again;
out:
spin_unlock(&host->lock);
return result;
}3、sdhci_tasklet_card
- 簡單流程說明：
- 當進行卡插入或者拔出的時候，sdhci controller（硬體）會檢測到其狀態發生變化
- sdhci controller（硬體）會設置中斷狀態寄存器中SDHCI_INT_CARD_INSERT或者SDHCI_INT_CARD_REMOVE位
- sdhci controller（硬體）觸發中段
- sdhci core中的中斷處理函數sdhci_irq被調用（軟體）
- sdhci_irq（軟體）去判斷出中斷狀態寄存器中SDHCI_INT_CARD_INSERT或者SDHCI_INT_CARD_REMOVE位被設置
- sdhci_irq執行host->card_tasklet，也就是我們這裡的sdhci_tasklet_card進行相應處理。
- sdhci_tasklet_card實現如下：
static void sdhci_tasklet_card(unsigned long param)
{
struct sdhci_host *host = (struct sdhci_host*)param; // 提取sdhci_host結構體
sdhci_card_event(host->mmc); // 發送事件，如果此時有mmc_request正在處理，則會複位數據線和命令線，終止mmc_request處理
mmc_detect_change(host->mmc, msecs_to_jiffies(200));
// 調用mmc_detect_change通知mmc core卡槽狀態發生了變化，剩下的就是mmc core的工作了
// mmc_detect_change實現具體參考《mmc core主模塊說明》
}4、sdhci_tasklet_finish
static void sdhci_tasklet_finish(unsigned long param)
{
//......過濾掉前面一些根據情況決定的複位操作
mmc_request_done(host->mmc, mrq);
// 調用mmc_request_done來通知mmc core 說mrq這個mmc request已經處理完成，至於處理完成的結果由上層自己解決
// mmc_request_done實現具體參考《mmc core主模塊說明》
sdhci_runtime_pm_put(host);
}5、struct mmc_host_ops sdhci_ops各個方法簡單說明
static const struct mmc_host_ops sdhci_ops = {
// post_req和pre_req是為了實現非同步請求處理而設置的
// 非同步請求處理就是指，當另外一個非同步請求還沒有處理完成的時候，可以先準備另外一個非同步請求而不必等待
// 具體參考《mmc core主模塊》
.pre_req = sdhci_pre_req,
.post_req = sdhci_post_req,
.request = sdhci_request, // host處理mmc請求的方法，在mmc_start_request中會調用
.set_ios = sdhci_set_ios, // 設置host的匯流排的io setting
.get_cd = sdhci_get_cd, // 檢測host的卡槽中card的插入狀態
.get_ro = sdhci_get_ro, // 獲取host上的card的讀寫屬性
.hw_reset = sdhci_hw_reset, // 硬體複位
.enable_sdio_irq = sdhci_enable_sdio_irq,
.start_signal_voltage_switch = sdhci_start_signal_voltage_switch, // 切換信號電壓的方法
.execute_tuning = sdhci_execute_tuning, // 執行tuning操作，為card選擇一個合適的採樣點
.card_event = sdhci_card_event,
.card_busy = sdhci_card_busy, // 用於檢測card是否處於busy狀態
.enable = sdhci_enable, // 使能host，當host被占用時（第一次調用mmc_claim_host）調用
.disable = sdhci_disable, // 禁用host，當host被釋放時（第一次調用mmc_release_host）調用
.stop_request = sdhci_stop_request, // 停止請求處理的方法
.get_xfer_remain = sdhci_get_xfer_remain,
.notify_load = sdhci_notify_load,
};
