MMC子系统分析

灰太狼 2023-08-17 17:12 6阅读 0赞

原文网址：[MMC子系统分析\_IT利刃出鞘的博客-CSDN博客\_mmc子系统][MMC_IT_-CSDN_mmc]

# 子系统概述 #

Linux kernel把mmc,sd以及sdio三者的驱动代码整合在一起，称mmc子系统。源码位于drivers/mmc下。  
其下有三个子目录，分别是：card,core,host。

*  card：构建一个块设备作为上层与mmc子系统沟通的桥梁；
 *  core：抽象了mmc,sd,sdio三者的操作。核心层封装了 MMC/SD 卡的命令，例如存储卡的识别，设置，读写。例如不管什么卡都应该有一些识别，设置，和读写的命令，这些流程都是必须要有的，只是具体对于不同的卡会有一些各自特有的操作。 core.c 文件是由 sd.c 、 mmc.c 两个文件支撑， core.c 把 MMC 卡、 SD 卡的共性抽象出来，它们的差别由 sd.c 和 sd\_ops.c 、 mmc.c 和 mmc\_ops.c 来完成。
 *  host：则是各类平台上的host驱动代码，包括如TI Omap的omap\_hsmmc,三星的s3cmci等。

**源码位置**

命令号：include/linux/mmc/mmc.h

# 相关节点 #

<table style="width:488px;"> 
 <tbody> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> 节点 </td> 
 <td style="vertical-align:top;width:346px;"> 含义 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmcblk0boot0 </td> 
 <td style="vertical-align:top;width:346px;"> boot0分区。主设备号：179；次设备号：8 &nbsp;&nbsp;&nbsp;&nbsp; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmcblkb0oot1 </td> 
 <td style="vertical-align:top;width:346px;"> boot0分区。主设备号：179；次设备号：9 &nbsp;&nbsp; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmc0 &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> 主节点。 &nbsp; 主设备号：179；次设备号：0 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmc01 &nbsp; &nbsp; &nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> 第1个分区。主设备号：179；次设备号：1 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> ... &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmc07 &nbsp; &nbsp; &nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> 第7个分区。主设备号：179；次设备号：7 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmc08 &nbsp; &nbsp; &nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> 第8个分区。主设备号：259；次设备号：0 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> ... &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmc09 &nbsp; &nbsp; &nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> 第9个分区。主设备号：259；次设备号：1 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;"> /dev/mmcblk0p10&nbsp;&nbsp; </td> 
 <td style="vertical-align:top;width:346px;"> 第9个分区。主设备号：259；次设备号：2 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:102.1pt;">...</td> 
 <td style="vertical-align:top;width:346px;"></td> 
 </tr> 
 </tbody> 
</table>

# card路径代码分析 #

**mmc/card/block.c**

mmc\_blk\_probe  
详细流程见：控制器代码分析=>mmc\_blk\_probe

static struct mmc\_driver mmc\_driver = \{  
.drv = \{  
.name = "mmcblk",  
.pm = &mmc\_blk\_pm\_ops,  
\},  
.probe = mmc\_blk\_probe,  
.remove = mmc\_blk\_remove,  
.shutdown = mmc\_blk\_shutdown,  
\};

mmc\_blk\_init 
//设置次设备数、主设备数 
perdev\_minors = CONFIG\_MMC\_BLOCK\_MINORS 
max\_devices = min(MAX\_DEVICES, (1 << MINORBITS) / perdev\_minors); 
//MMC\_BLOCK\_MAJOR是179 
register\_blkdev(MMC\_BLOCK\_MAJOR, "mmc"); //block/genhd.c 
mmc\_register\_driver(&mmc\_driver) //mmc/core/bus.c 
drv->drv.bus = &mmc\_bus\_type 
driver\_register(&drv->drv)

module\_init(mmc\_blk\_init);

# 读写流程 #

mmc\_queue\_thread是在mmc\_init\_queue中起的线程，主要作用是完成上层发送的请求进行处理。

mmc\_queue\_thread  //mmc/card/queue.c  
struct mmc\_queue \*mq = d;  
struct request\_queue \*q = mq->queue;

req = blk\_fetch\_request(q); //block/blk-core.c  
mmc\_blk\_issue\_rq(mq, req); //mmc/card/block.c  
//切换分区：选择要使用哪个分区。（boot还是user data等）  
mmc\_blk\_part\_switch(card, md); //mmc/card/block.c  
//根据req->cmd\_flags确定操作：REQ\_OP\_READ、REQ\_OP\_WRITE、REQ\_OP\_FLUSH等  
//读写以外的操作，第2个参数都是NULL  
mmc\_blk\_issue\_rw\_rq(mq, req); //mmc/card/block.c  
//尝试把当前request和队列中的其他request合并，以增强性能  
mmc\_blk\_prep\_packed\_list(mq, rqc); //mmc/card/block.c  
//正常走此分支：设置读写命令号（多/单 块）等  
mmc\_blk\_rw\_rq\_prep(mq->mqrq\_cur, card, 0, mq); //mmc/card/block.c  
mmc\_start\_req(card->host, areq, (int \*) &status); //mmc/core/core.c  
//传进来第2个参数名为mrq  
mmc\_wait\_for\_data\_req\_done(host, host->areq->mrq, areq); //mmc/core/core.c  
//等待。退出条件：上一个请求结束或者本请求是新请求  
wait\_event\_interruptible(context\_info->wait, (context\_info->is\_done\_rcv ||  
context\_info->is\_new\_req));  
\_\_mmc\_start\_request(host, mrq); //mmc/core/core.c  
mmc\_retune(host); //mmc/core/host.c  
if (!**host->need\_retune** || host->doing\_retune || !host->card)  
return 0;  
host->ops->request(host, mrq);

# 控制器代码分析 #

## 控制器入口 ##

mmc/host/myhost\_mmc.c

myhost\_mmc\_probe(struct platform\_device \*pdev) //myhost\_mmc.c  
struct sdhci\_host \*host;  
struct mmc\_host \*mmc = NULL;  
mmc = mmc\_alloc\_host(sizeof(struct myhost\_mmc\_host), &pdev->dev); //core/host.c  
//传进来第2个参数名为dev  
struct mmc\_host \*host;  
host = kzalloc(sizeof(struct mmc\_host) + extra, GFP\_KERNEL);  
host->parent = dev;  
init\_waitqueue\_head(&host->wq);  
INIT\_DELAYED\_WORK(&host->detect, mmc\_rescan); //mmc\_rescan在 core/core.c定义  
platform\_set\_drvdata(pdev, mmc);  
pdev->dev.driver\_data = mmc  
host = mmc\_priv(mmc); //host = mmc->private  
host->mmc = mmc;  
mmc->ops = &myhost\_mmc\_ops;  
host->dma\_des = dma\_alloc\_coherent(&pdev->dev, MAX\_DMA\_DES \* sizeof(desc\_tab),  
&host->dma\_des\_phy, GFP\_KERNEL);  
mmc\_of\_parse(host->mmc) //core/host.c  
解析bus\_width,max-frequency,写保护、速率、电压等  
myhost\_mmc\_host\_init(host);  
irq = platform\_get\_irq(pdev, 0);  
host->irq = irq;  
request\_threaded\_irq()  
tasklet\_init(&host->finish\_tasklet, myhostmmc\_tasklet\_finish, (unsigned long)host);  
setup\_timer(&host->timer, myhostmmc\_timeout\_timer, (unsigned long)host);  
mmc\_add\_host(mmc); //core/host.c  
//传进来的参数名为host  
device\_add(&host->class\_dev);  
led\_trigger\_register\_simple(dev\_name(&host->class\_dev), &host->led); //drivers/leds/led-trigger.c  
mmc\_start\_host(host); //core/core.c  
mmc\_claim\_host(host); //mmc/core.h  
\_\_mmc\_claim\_host(host, NULL); //core/core.c  
host->claimed = 1;  
host->claimer = current;  
host->claim\_cnt += 1;  
mmc\_power\_up(host, host->ocr\_avail) //core/core.c  
mmc\_set\_initial\_state(host); //core/core.c  
//传进来参数名为host  
mmc\_retune\_disable(host); //mmc/core/host.c  
host->**need\_retune** = 0;  
给host->ios的bus\_mode,bus\_width,timing等赋值  
mmc\_set\_ios(host); //core/core.c  
host->ops->set\_ios(host, ios);  
//依次尝试切换为：3.3v，1.8v，1.2v  
\_\_mmc\_set\_signal\_voltage(host, MMC\_SIGNAL\_VOLTAGE\_330) //core/core.c  
//设置host的电压  
host->ops->start\_signal\_voltage\_switch(host, &host->ios)  
dev\_dbg(mmc\_dev(host), "Initial signal voltage of ...v\\n");  
host->ios.clock = host->f\_init;  
host->ios.power\_mode = MMC\_POWER\_ON;  
mmc\_set\_ios(host) //core/core.c  
host->ops->set\_ios(host, ios);  
mmc\_gpiod\_request\_cd\_irq(host); //core/slot-gpio.c  
\_mmc\_detect\_change(host, 0, false); //core/core.c  
host->detect\_change = 1;  
mmc\_schedule\_delayed\_work(&host->detect, delay); //core/core.c  
queue\_delayed\_work(system\_freezable\_wq, work, delay); //include/linux/workqueue.h  
mmc\_rescan //core/core.c 会被调用到

## mmc\_rescan ##

//core/core.c: static const unsigned freqs\[\] = \{ 400000, 300000, 200000, 100000 \};

mmc\_rescan(struct work\_struct \*work) //core/core.c 
struct mmc\_host \*host = container\_of(work, struct mmc\_host, detect.work); 
//**非核心函数暂时忽略** 
host->rescan\_entered = 1; 
host->detect\_change = 0; 
for (i = 0; i < ARRAY\_SIZE(freqs); i++) \{ 
if (!mmc\_rescan\_try\_freq(host, max(freqs\[i\], host->f\_min))) 
break; 
if (freqs\[i\] <= host->f\_min) 
break; 
\}

## mmc\_rescan\_try\_freq ##

mmc\_rescan\_try\_freq(host, max(freqs\[i\], host->f\_min) //core/core.c  
//传进来第1个参数为：struct mmc\_host \*host  
mmc\_power\_up(host, host->ocr\_avail); //core/core.c  
//host->ocr\_avail在控制器驱动中指定的。此函数流程在上边有。  
...  
host->ops->set\_ios(host, ios);  
mmc\_hw\_reset\_for\_init(host); //core/core.c  
host->ops->hw\_reset(host);

//命令号：0；参数：0  
mmc\_go\_idle(host);

//命令号：8。为了兼容SD2.0。 MMC\_CAP2\_NO\_SD对应于设备树的no-sd。  
if (!(host->caps2 & MMC\_CAP2\_NO\_SD))  
mmc\_send\_if\_cond(host, host->ocr\_avail);  
  
//依次探测SDIO,SD,eMMC（顺序很重要）  
**mmc\_attach\_mmc**(host) //core/mmc.c  
//传进来第1个参数为：struct mmc\_host \*host  
如果host不是spi模式 //!((host)->caps & MMC\_CAP\_SPI)  
//一般走此分支。只有mmc/host/mmc\_spi.c会指定为MMC\_CAP\_SPI  
mmc\_set\_bus\_mode(host, MMC\_BUSMODE\_OPENDRAIN); //core/core.c  
mmc\_set\_ios(host); //mmc/core/core.c  
//命令号：2；参数：0  
mmc\_send\_op\_cond(host, 0, &ocr); //core/mmc\_ops.c  
//传进来第二个参数名为ocr，第三个参数名为rocr  
cmd.flags = MMC\_RSP\_SPI\_R1 | MMC\_RSP\_R3 | MMC\_CMD\_BCR;  
//发送命令并等待命令结束  
mmc\_wait\_for\_cmd(host, &cmd, 0) //mmc/core/core.c  
//第2个参数名：cmd  
struct mmc\_request mrq = \{NULL\};  
mrq.cmd = cmd;  
cmd->data = NULL;  
mmc\_wait\_for\_req(host, &mrq)=> \_\_mmc\_start\_req(host, mrq)=>mmc\_start\_request(host, mrq);  
\_\_mmc\_start\_request(host, mrq); //mmc/core/core.c  
host->ops->request(host, mrq);  
 \*rocr = cmd.resp\[0\]  
mmc\_attach\_bus(host, &mmc\_ops); //core/core.c  
//传进来第2个参数名为ops  
host->bus\_ops = ops;  
host->bus\_refs = 1;  
host->bus\_dead = 0;  
//根据host->ocr\_avail屏蔽不支持的电压，选择最低电压  
rocr = mmc\_select\_voltage(host, ocr); //core/core.c  
ocr &= host->ocr\_avail;  
...  
 mmc\_init\_card(host, rocr, NULL); //core/mmc.c  
//struct mmc\_card \*card;  
mmc\_go\_idle; //CMD0 mmc/core/mmc\_ops.c  
mmc\_send\_op\_cond; //CMD1 mmc/core/mmc\_ops.c  
mmc\_all\_send\_cid; //CMD2 mmc/core/mmc\_ops.c  
mmc\_set\_relative\_addr; //CMD3 mmc/core/mmc\_ops.c  
mmc\_send\_csd; //CMD9 mmc/core/mmc\_ops.c  
mmc\_decode\_csd(card); // mmc/core/mmc.c  
mmc\_decode\_cid(card); // mmc/core/mmc.c  
mmc\_select\_card; //CMD7 mmc/core/mmc\_ops.c  
mmc\_read\_ext\_csd(card); // mmc/core/mmc.c  
mmc\_decode\_ext\_csd(card, ext\_csd) //mmc/core/mmc.c  
mmc\_select\_card\_type(card); //mmc/core/mmc.c  
根据**caps的速度模式和extcsd读出的数据**确定类型  
读写erase\_size(依赖于CID和Extended CSD)  
//切换分区  
mmc\_switch(card, ..., EXT\_CSD\_PART\_CONFIG, ...) //CMD6 mmc/core/mmc\_ops.c  
mmc\_select\_timing(card) //mmc/core/mmc.c  
//SWITCH命令号：6  
mmc\_select\_hs400es/mmc\_select\_hs200/mmc\_select\_hs //mmc/core/mmc.c  
前两个：  
设置host：电压、driver\_strength、driver\_type、bus\_width（mmc\_switch成功则设置host的）  
设置timing：\_\_mmc\_switch成功则设置host的  
第三个：直接\_\_mmc\_switch到高速模式。  
mmc\_set\_bus\_speed(card); //mmc/core/mmc.c  
//**设置时钟频率**  
mmc\_set\_clock(card->host, max\_dtr); //mmc/core/core.c  
如果频率小于等于maxhost->f\_max（设备树max\_frequency指定），则设置。  
否则设为设备树指定的。  
mmc\_set\_ios(host); //mmc/core/core.c  
//参数类型为struct mmc\_host \*  
struct mmc\_ios \*ios = &host->ios;

pr\_debug("%s: clock %uHz busmode %u powermode %u cs %u Vdd %u " 
"width %u timing %u\\n", mmc\_hostname(host), ios->clock, ios->bus\_mode, 
ios->power\_mode, ios->chip\_select, ios->vdd, 1 << ios->bus\_width, ios->timing); 
打印示例：mmc0: clock 25000000Hz busmode 2 powermode 2 cs 0 Vdd 21 width 1 timing 2 
host->ops->set\_ios(host, ios);

mmc\_card\_hs200(card) //include/linux/mmc/mmc.h  
return card->host->ios.timing == MMC\_TIMING\_MMC\_HS200;  
//如果上边返回1，则执行下边的。//到\#\#\#  
mmc\_hs200\_tuning(card) //mmc/core/mmc.c  
若有host->ops->prepare\_hs400\_tuning则执行  
mmc\_execute\_tuning(card) //mmc/core/core.c  
**host->ops->execute\_tuning**(host, opcode)  
mmc\_select\_hs400(card) //mmc/core/mmc.c  
\_\_mmc\_switch到HS的timing,成功则mmc\_set\_ios切换host的timing到HS。  
\_\_mmc\_switch到8 bit DDR（dual data rate）  
\_\_mmc\_switch到HS400的timing，成功则mmc\_set\_ios切换host的timing到HS400。  
mmc\_set\_bus\_speed(card); //mmc/core/mmc.c  
mmc\_set\_ios设置尽量高的频率 //mmc/core/core.c  
//频率不会超过host->f\_max（即设备树的max\_frequency项） **\#\#\#**  
否则  
mmc\_select\_bus\_width(card); //mmc/core/mmc.c  
// 依次尝试设为8bit,4bit,1bit  
先mmc\_switch()发送CMD6,设置**外设位宽**（EXT\_CSD寄存器）  
若成功则设置**hos**t的。mmc\_set\_bus\_width=> mmc\_set\_ios(host)=>

card = mmc\_alloc\_card(host, &mmc\_type);  
card->dev.bus = &mmc\_bus\_type;  
card->dev.type = type;  
card->ocr = ocr;  
card->type = MMC\_TYPE\_MMC;  
card->rca = 1;  
host->card = card;  
  
mmc\_add\_card(host->card); //core/bus.c  
switch (card->type) \{  
case MMC\_TYPE\_MMC:  
type = "MMC";  
...  
\}  
确定uhs\_bus\_speed\_mode（根据card->host->ios.timing）  
**pr\_info**("%s: new %s%s%s%s%s%s card at address %04x\\n",  
mmc\_hostname(card->host),  
mmc\_card\_uhs(card) ? "ultra high speed " :  
(mmc\_card\_hs(card) ? "high speed " : ""),  
mmc\_card\_hs400(card) ? "HS400 " :  
(mmc\_card\_hs200(card) ? "HS200 " : ""),  
mmc\_card\_hs400es(card) ? "Enhanced strobe " : "",  
mmc\_card\_ddr52(card) ? "DDR " : "",  
uhs\_bus\_speed\_mode, type, card->rca);  
device\_add(&card->dev) //base/core.c  
先调用mmc\_bus\_type的match函数 //此函数直接返回1。  
//device\_add=> bus\_probe\_device中有个if (bus->p->drivers\_autoprobe)，  
//这个是在core/bus.c=>mmc\_register\_bus函数里指定的  
match成功，调用mmc\_bus\_type的probe函数  
会调用driver->probe => mmc\_driver.probe //card/block.c  
mmc\_blk\_probe //card/block.c 详细流程见下边  
//driver->probe对应mmc\_driver.probe原因：  
//card/block.c=>mmc\_blk\_init => mmc\_register\_driver(&mmc\_driver);  
mmc\_card\_set\_present(card); //include/linux/mmc/card.h  
card->state |= MMC\_STATE\_PRESENT;  
mmc\_claim\_host(host); //mmc/core.h

## mmc\_blk\_probe ##

mmc\_blk\_probe //card/block.c

struct mmc\_blk\_data \*md, \*part\_md;  
char cap\_str\[10\];  
md = mmc\_blk\_alloc(card); //card/block.c  
mmc\_blk\_alloc\_req(card, &card->dev, size, false, NULL, MMC\_BLK\_DATA\_AREA\_MAIN); //card/block.c

//传进来第1个参数名为card  
struct mmc\_blk\_data \*md;

md = kzalloc(sizeof(struct mmc\_blk\_data), GFP\_KERNEL);  
md->disk = alloc\_disk(perdev\_minors);  
mmc\_init\_queue(&md->queue, card, &md->lock, subname); //card/queue.c  
//传进来第1个参数名为mq,第2个为card  
blk\_queue\_prep\_rq(mq->queue, mmc\_prep\_request);  
//分配max\_segs个scatterlist用于request请求  
//（只是分配scatterlist，并未分配存放数据的内存）  
mqrq\_cur->sg = mmc\_alloc\_sg(host->max\_segs, &ret);  
mqrq\_prev->sg = mmc\_alloc\_sg(host->max\_segs, &ret);  
//起一个kennel thread运行mmc\_queue\_thread来处理上层发送下来的request，  
//对每个reqeust执行issue\_fn回调  
//注意：issue\_fn回调在下边指定为mmc\_blk\_issure\_req。  
//mmc\_blk\_issue\_rq是具体的mmc request处理函数。  
mq->thread = kthread\_run(mmc\_queue\_thread, mq, "mmcqd/%d%s",  
host->index, subname ? subname : "");  
//MMC\_BLOCK\_MAJOR是179  
md->disk->major = MMC\_BLOCK\_MAJOR;  
snprintf(md->disk->disk\_name, sizeof(md->disk->disk\_name),  
"mmcblk%u%s", card->host->index, subname ? subname : "");

获得容量：从md->disk中获得容量，写到cap\_str  
打印：pr\_info("%s: %s %s %s %s\\n", md->disk->disk\_name,  
mmc\_card\_id(card), mmc\_card\_name(card), cap\_str, md->read\_only ? "(ro)" : "");  
//打印示例：mmcblk2: mmc2:0001 8GME4R 7.28 GiB  
mmc\_blk\_alloc\_parts(card, md) //card/block.c  
对于小于card->nr\_parts的每一个card->part\[idx\] //这些是boot、general、user data等分区  
mmc\_blk\_alloc\_part(card, md, ...); //card/block.c  
struct mmc\_blk\_data \*part\_md;  
part\_md = mmc\_blk\_alloc\_req(card, disk\_to\_dev(md->disk),...); //card/block.c  
//传进来第2个参数名为parent  
md->disk = alloc\_disk(perdev\_minors);  
md->parent = parent;  
mmc\_init\_queue(&md->queue, card, &md->lock, subname);  
snprintf(md->disk->disk\_name, sizeof(md->disk->disk\_name),  
"mmcblk%u%s", card->host->index, subname ? subname : "");  
list\_add(&part\_md->part, &md->part);  
打印：pr\_info("%s: %s %s partition %u %s\\n", part\_md->disk->disk\_name,  
mmc\_card\_id(card), mmc\_card\_name(card), part\_md->part\_type, cap\_str)  
//打印示例：mmcblk2boot0: mmc2:0001 8GME4R partition 1 4.00 MiB  
mmc\_add\_disk(md) //mmc/card/block.c  
device\_add\_disk(md->parent, md->disk); //block/partitions/genhd.c  
list\_for\_each\_entry(part\_md, &md->part, part) \{  
mmc\_add\_disk(part\_md)

# mmc\_attach\_sd流程 #

mmc\_attach\_sd //mmc/core/sd.c  
//命令号：41  
mmc\_send\_app\_op\_cond(host, 0, &ocr); //mmc/core/sd\_ops.c  
rocr = mmc\_select\_voltage(host, ocr); //mmc/core/core.c  
//屏蔽不支持的电压，选择最小电压  
**mmc**\_sd\_init\_card(host, rocr, NULL); //mmc/core/sd.c  
//第一个参数类型为mmc\_host  
mmc\_sd\_get\_cid(host, ocr, cid, &rocr); //mmc/core/sd.c  
mmc\_go\_idle(host);  
//命令号：8 （为兼容SD2.0，发命令41之前必须发命令8）  
mmc\_send\_if\_cond(host, ocr);  
//命令号：41  
mmc\_send\_app\_op\_cond(host, ocr, rocr);  
mmc\_all\_send\_cid(host, cid);  
  
if (host->ops->init\_card)  
host->ops->init\_card(host, card);

mmc\_send\_relative\_addr(host, &card->rca); //mmc/core/sd\_ops.c  
mmc\_sd\_get\_csd(host, card); //mmc/core/sd.c  
mmc\_select\_card(card); //mmc/core/mmc\_ops.c  
mmc\_sd\_setup\_card(host, card, oldcard != NULL); //mmc/core/sd.c

//命令号：6  
mmc\_sd\_switch\_hs(card); //mmc/core/sd.c  
mmc\_set\_timing(card->host, MMC\_TIMING\_SD\_HS); //mmc/core/core.c  
host->ios.timing = timing;  
mmc\_set\_ios(host); //mmc/core/core.c  
struct mmc\_ios \*ios = &host->ios;

host->ios.clock = hz;  
mmc\_set\_ios(host); //mmc/core/core.c

//先发命令55，后发送命令6  
mmc\_app\_set\_bus\_width(card, MMC\_BUS\_WIDTH\_4); //mmc/core/sd\_ops.c  
mmc\_set\_bus\_width(host, MMC\_BUS\_WIDTH\_4); //mmc/core/core.c  
host->ios.bus\_width = width;  
mmc\_set\_ios(host); //mmc/core/core.c

**mmc**\_add\_card(host->card); //mmc/core/bus.c  
pr\_info("%s: new %s%s%s%s%s%s card at address %04x\\n",  
mmc\_hostname(card->host),  
mmc\_card\_uhs(card) ? "ultra high speed " :  
(mmc\_card\_hs(card) ? "high speed " : ""),  
mmc\_card\_hs400(card) ? "HS400 " :  
(mmc\_card\_hs200(card) ? "HS200 " : ""),  
mmc\_card\_hs400es(card) ? "Enhanced strobe " : "",  
mmc\_card\_ddr52(card) ? "DDR " : "",  
uhs\_bus\_speed\_mode, type, card->rca);  
打印示例：mmc0: new high speed SDXC card at address 59b4

# 打印分区信息流程 #

device\_add\_disk  //block/partitions/genhd.c  
register\_disk(parent, disk); //block/partitions/genhd.c  
blkdev\_get(bdev, FMODE\_READ, NULL); //fs/block\_dev.c  
\_\_blkdev\_get(bdev, mode, 0); //fs/block\_dev.c  
rescan\_partitions(disk, bdev); //block/partitions-generic.c  
check\_partition(disk, bdev) //block/partions/check.c  
printk(KERN\_INFO "%s", state->pp\_buf)

打印示例：mmcblk0: p1(bld) p2(env) p3(kernel) p4(fs)

# 设备树速度模式 #

<table> 
 <tbody> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> 设备树 </td> 
 <td style="vertical-align:top;width:225px;"> host成员 </td> 
 <td style="vertical-align:top;width:82px;"> 硬件模式 </td> 
 <td style="vertical-align:top;width:141.25pt;"> 最大速度宏 </td> 
 <td style="vertical-align:top;width:73.1pt;"> 宏对应的值 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> cap-mmc-highspeed </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP_MMC_HIGHSPEED </td> 
 <td style="vertical-align:top;width:82px;"> HS_26 HS_52 </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HIGH_26_MAX_DTR MMC_HIGH_52_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 26M 52M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-ddr-1_8v </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP_1_8V_DDR </td> 
 <td style="vertical-align:top;width:82px;"> DDR_1_8V </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HIGH_DDR_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 52M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-ddr-1_2v </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP_1_2V_DDR </td> 
 <td style="vertical-align:top;width:82px;"> DDR_1_2V </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HIGH_DDR_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 52M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-hs200-1_8v </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP2_HS200_1_8V_SDR </td> 
 <td style="vertical-align:top;width:82px;"> HS200_1_8V </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HS200_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 200M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-hs200-1_2v </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP2_HS200_1_2V_SDR </td> 
 <td style="vertical-align:top;width:82px;"> HS200_1_2V </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HS200_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 200M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-hs400-1_8v </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP2_HS400_1_8V MMC_CAP2_HS200_1_8V_SDR </td> 
 <td style="vertical-align:top;width:82px;"> HS400_1_8V </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HS200_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 200M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-hs400-1_2v </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP2_HS400_1_2V MMC_CAP2_HS200_1_2V_SDR </td> 
 <td style="vertical-align:top;width:82px;"> HS400_1_2V </td> 
 <td style="vertical-align:top;width:141.25pt;"> MMC_HS200_MAX_DTR </td> 
 <td style="vertical-align:top;width:73.1pt;"> 200M </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:195px;"> mmc-hs400-enhanced-strobe </td> 
 <td style="vertical-align:top;width:225px;"> MMC_CAP2_HS400_ES </td> 
 <td style="vertical-align:top;width:82px;"> HS400ES </td> 
 <td style="vertical-align:top;width:141.25pt;"> </td> 
 <td style="vertical-align:top;width:73.1pt;"> </td> 
 </tr> 
 </tbody> 
</table>

**源码位置**：  
myhost\_mmc\_probe //mmc/host/myhost\_mmc.c  
mmc\_rescan //core/core.c  
mmc\_rescan\_try\_freq(host, max(freqs\[i\], host->f\_min) //mmc/core/core.c  
mmc\_attach\_mmc(host) //mmc/core/mmc.c  
mmc\_init\_card(host, rocr, NULL); //mmc/core/mmc.c  
mmc\_read\_ext\_csd(card); //mmc/core/mmc.c  
mmc\_get\_ext\_csd(card, &ext\_csd); //mmc/core/mmc\_ops.c  
mmc\_decode\_ext\_csd(card, ext\_csd); //mmc/core/mmc.c  
mmc\_select\_card\_type(card); //mmc/core/mmc.c

# reboot调用到的流程 #

**调用流程**  
mmc\_bus\_shutdown //mmc/core/bus.c  
struct mmc\_host \*host = card->host;  
host->bus\_ops->shutdown(host)  
mmc\_shutdown //mmc/core/mmc.c

**shutdown函数注册流程**  
mmc\_init //mmc/core/core.c  
mmc\_register\_bus() //mmc/core/bus.c  
bus\_register(&mmc\_bus\_type) //mmc\_bus\_type.shutdown = mmc\_bus\_shutdown  
  
mmc\_attach\_mmc(host) //mmc/core/mmc.c  
//mmc\_ops在mmc/core/mmc.c定义  
mmc\_attach\_bus(host, &mmc\_ops); //mmc/core/core.c  
host->bus\_ops = ops; //mmc\_ops.shutdown = mmc\_shutdown;

[MMC_IT_-CSDN_mmc]: https://knife.blog.csdn.net/article/details/101778289