///
第一条线 mmc子系统核心初始化
drivers/mmc/core/core.c
//子系统初始化
subsys_initcall(mmc_init);
第二条线 mmc控制器平台驱动注册
module_init(sdhci_drv_init);
第三条线 磁盘设备驱动注册
drivers/mmc/card/block.c
module_init(
mmc_blk_init);
//////////////////////////////////////////////////////////////////////////////////////////////////////////
module_init(mmc_blk_init);
module_exit(mmc_blk_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Multimedia Card (MMC) block device driver");
static void __exit mmc_blk_exit(void)
{
mmc_unregister_driver(&mmc_driver);
unregister_blkdev(MMC_BLOCK_MAJOR, "mmc");
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int __init mmc_blk_init(void)
{
int res;
//block/genhd.c 或linux/fs.h
//参数1 ：主设备号
//参数2：主设备名字（在/proc/devices中显示的名字）
//将块设备名和主设备号注册到块层中
res = register_blkdev(MMC_BLOCK_MAJOR, "mmc");
if (res)
goto out;
//将mmc_driver设备驱动注册到驱动模型中
res = mmc_register_driver(&mmc_driver);
if (res)
goto out2;
return 0;
out2:
unregister_blkdev(MMC_BLOCK_MAJOR, "mmc");
out:
return res;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
/*
* MMC device driver (e.g., Flash card, I/O card...)
*/
struct mmc_driver {
struct device_driver drv;//当前驱动
int (*probe)(struct mmc_card *);//驱动的匹配到之后的处理函数
void (*remove)(struct mmc_card *);
int (*suspend)(struct mmc_card *, pm_message_t);
int (*resume)(struct mmc_card *);
};
///////////////////////////////////////////////////////////////////////////////////////////////////////////
static struct mmc_driver mmc_driver = {
.drv = {
.name = "mmcblk",
},
.probe = mmc_blk_probe,
.remove = mmc_blk_remove,
.suspend = mmc_blk_suspend,
.resume = mmc_blk_resume,
};
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static DECLARE_BITMAP(dev_use, MMC_NUM_MINORS);
/*
* There is one mmc_blk_data per slot.
*/
struct mmc_blk_data {
spinlock_t lock;
struct gendisk *disk;
struct mmc_queue queue;
unsigned int usage;
unsigned int read_only;
};
static DEFINE_MUTEX(open_lock);
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
{
struct mmc_blk_data *md;
mutex_lock(&open_lock);
md = disk->private_data;
if (md && md->usage == 0)
md = NULL;
if (md)
md->usage++;
mutex_unlock(&open_lock);
return md;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static void mmc_blk_put(struct mmc_blk_data *md)
{
mutex_lock(&open_lock);
md->usage--;
if (md->usage == 0) {
int devidx = MINOR(disk_devt(md->disk)) >> MMC_SHIFT;
__clear_bit(devidx, dev_use);
put_disk(md->disk);
kfree(md);
}
mutex_unlock(&open_lock);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int mmc_blk_open(struct block_device *bdev, fmode_t mode)
{
struct mmc_blk_data *md = mmc_blk_get(bdev->bd_disk);
int ret = -ENXIO;
if (md) {
if (md->usage == 2)
check_disk_change(bdev);
ret = 0;
if ((mode & FMODE_WRITE) && md->read_only) {
mmc_blk_put(md);
ret = -EROFS;
}
}
return ret;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int mmc_blk_release(struct gendisk *disk, fmode_t mode)
{
struct mmc_blk_data *md = disk->private_data;
mmc_blk_put(md);
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int
mmc_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
geo->cylinders = get_capacity(bdev->bd_disk) / (4 * 16);
geo->heads = 4;
geo->sectors = 16;
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static struct block_device_operations mmc_bdops = {
.open = mmc_blk_open,
.release = mmc_blk_release,
.getgeo = mmc_blk_getgeo,
.owner = THIS_MODULE,
};
//////////////////////////////////////////////////////////////////////////////////////////////////////////
struct mmc_blk_request {
struct mmc_request mrq;
struct mmc_command cmd;
struct mmc_command stop;
struct mmc_data data;
};
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
{
int err;
u32 blocks;
struct mmc_request mrq;
struct mmc_command cmd;
struct mmc_data data;
unsigned int timeout_us;
struct scatterlist sg;
memset(&cmd, 0, sizeof(struct mmc_command));
cmd.opcode = MMC_APP_CMD;
cmd.arg = card->rca << 16;
cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
err = mmc_wait_for_cmd(card->host, &cmd, 0);
if (err)
return (u32)-1;
if (!mmc_host_is_spi(card->host) && !(cmd.resp[0] & R1_APP_CMD))
return (u32)-1;
memset(&cmd, 0, sizeof(struct mmc_command));
cmd.opcode = SD_APP_SEND_NUM_WR_BLKS;
cmd.arg = 0;
cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
memset(&data, 0, sizeof(struct mmc_data));
data.timeout_ns = card->csd.tacc_ns * 100;
data.timeout_clks = card->csd.tacc_clks * 100;
timeout_us = data.timeout_ns / 1000;
timeout_us += data.timeout_clks * 1000 /
(card->host->ios.clock / 1000);
if (timeout_us > 100000) {
data.timeout_ns = 100000000;
data.timeout_clks = 0;
}
data.blksz = 4;
data.blocks = 1;
data.flags = MMC_DATA_READ;
data.sg = &sg;
data.sg_len = 1;
memset(&mrq, 0, sizeof(struct mmc_request));
mrq.cmd = &cmd;
mrq.data = &data;
sg_init_one(&sg, &blocks, 4);
mmc_wait_for_req(card->host, &mrq);
if (cmd.error || data.error)
return (u32)-1;
blocks = ntohl(blocks);
return blocks;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
{
struct mmc_blk_data *md = mq->data;
struct mmc_card *card = md->queue.card;
struct mmc_blk_request brq;
int ret = 1;
mmc_claim_host(card->host);
do {
struct mmc_command cmd;
u32 readcmd, writecmd;
memset(&brq, 0, sizeof(struct mmc_blk_request));
brq.mrq.cmd = &brq.cmd;
brq.mrq.data = &brq.data;
brq.cmd.arg = req->sector;
if (!mmc_card_blockaddr(card))
brq.cmd.arg <<= 9;
brq.cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
brq.data.blksz = 512;
brq.stop.opcode = MMC_STOP_TRANSMISSION;
brq.stop.arg = 0;
brq.stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
brq.data.blocks = req->nr_sectors;
if (brq.data.blocks > 1) {
/* SPI multiblock writes terminate using a special
* token, not a STOP_TRANSMISSION request.
*/
if (!mmc_host_is_spi(card->host)
|| rq_data_dir(req) == READ)
brq.mrq.stop = &brq.stop;
readcmd = MMC_READ_MULTIPLE_BLOCK;
writecmd = MMC_WRITE_MULTIPLE_BLOCK;
} else {
brq.mrq.stop = NULL;
readcmd = MMC_READ_SINGLE_BLOCK;
writecmd = MMC_WRITE_BLOCK;
}
if (rq_data_dir(req) == READ) {
brq.cmd.opcode = readcmd;
brq.data.flags |= MMC_DATA_READ;
} else {
brq.cmd.opcode = writecmd;
brq.data.flags |= MMC_DATA_WRITE;
}
mmc_set_data_timeout(&brq.data, card);
brq.data.sg = mq->sg;
brq.data.sg_len = mmc_queue_map_sg(mq);
mmc_queue_bounce_pre(mq);
mmc_wait_for_req(card->host, &brq.mrq);
mmc_queue_bounce_post(mq);
/*
* Check for errors here, but don't jump to cmd_err
* until later as we need to wait for the card to leave
* programming mode even when things go wrong.
*/
if (brq.cmd.error) {
printk(KERN_ERR "%s: error %d sending read/write command\n",
req->rq_disk->disk_name, brq.cmd.error);
}
if (brq.data.error) {
printk(KERN_ERR "%s: error %d transferring data\n",
req->rq_disk->disk_name, brq.data.error);
}
if (brq.stop.error) {
printk(KERN_ERR "%s: error %d sending stop command\n",
req->rq_disk->disk_name, brq.stop.error);
}
if (!mmc_host_is_spi(card->host) && rq_data_dir(req) != READ) {
do {
int err;
cmd.opcode = MMC_SEND_STATUS;
cmd.arg = card->rca << 16;
cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
err = mmc_wait_for_cmd(card->host, &cmd, 5);
if (err) {
printk(KERN_ERR "%s: error %d requesting status\n",
req->rq_disk->disk_name, err);
goto cmd_err;
}
/*
* Some cards mishandle the status bits,
* so make sure to check both the busy
* indication and the card state.
*/
} while (!(cmd.resp[0] & R1_READY_FOR_DATA) ||
(R1_CURRENT_STATE(cmd.resp[0]) == 7));
#if 0
if (cmd.resp[0] & ~0x00000900)
printk(KERN_ERR "%s: status = %08x\n",
req->rq_disk->disk_name, cmd.resp[0]);
if (mmc_decode_status(cmd.resp))
goto cmd_err;
#endif
}
if (brq.cmd.error || brq.data.error || brq.stop.error)
goto cmd_err;
/*
* A block was successfully transferred.
*/
spin_lock_irq(&md->lock);
ret = __blk_end_request(req, 0, brq.data.bytes_xfered);
spin_unlock_irq(&md->lock);
} while (ret);
mmc_release_host(card->host);
return 1;
cmd_err:
/*
* If this is an SD card and we're writing, we can first
* mark the known good sectors as ok.
*
* If the card is not SD, we can still ok written sectors
* as reported by the controller (which might be less than
* the real number of written sectors, but never more).
*
* For reads we just fail the entire chunk as that should
* be safe in all cases.
*/
if (rq_data_dir(req) != READ) {
if (mmc_card_sd(card)) {
u32 blocks;
blocks = mmc_sd_num_wr_blocks(card);
if (blocks != (u32)-1) {
spin_lock_irq(&md->lock);
ret = __blk_end_request(req, 0, blocks << 9);
spin_unlock_irq(&md->lock);
}
} else {
spin_lock_irq(&md->lock);
ret = __blk_end_request(req, 0, brq.data.bytes_xfered);
spin_unlock_irq(&md->lock);
}
}
mmc_release_host(card->host);
spin_lock_irq(&md->lock);
while (ret)
ret = __blk_end_request(req, -EIO, blk_rq_cur_bytes(req));
spin_unlock_irq(&md->lock);
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static inline int mmc_blk_readonly(struct mmc_card *card)
{
return mmc_card_readonly(card) ||
!(card->csd.cmdclass & CCC_BLOCK_WRITE);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
{
struct mmc_blk_data *md;
int devidx, ret;
devidx = find_first_zero_bit(dev_use, MMC_NUM_MINORS);
if (devidx >= MMC_NUM_MINORS)
return ERR_PTR(-ENOSPC);
__set_bit(devidx, dev_use);
md = kzalloc(sizeof(struct mmc_blk_data), GFP_KERNEL);
if (!md) {
ret = -ENOMEM;
goto out;
}
/*
* Set the read-only status based on the supported commands
* and the write protect switch.
*/
md->read_only = mmc_blk_readonly(card);
//分配通用gendisk解构体
md->disk = alloc_disk(1 << MMC_SHIFT);
if (md->disk == NULL) {
ret = -ENOMEM;
goto err_kfree;
}
spin_lock_init(&md->lock);
md->usage = 1;
//initialise a queue structure.
//初始化请求队列
ret = mmc_init_queue(&md->queue, card, &md->lock);
if (ret)
goto err_putdisk;
md->queue.issue_fn = mmc_blk_issue_rq;
md->queue.data = md;
md->disk->major = MMC_BLOCK_MAJOR;
md->disk->first_minor = devidx << MMC_SHIFT;
md->disk->fops = &mmc_bdops;
md->disk->private_data = md;
md->disk->queue = md->queue.queue;
md->disk->driverfs_dev = &card->dev;
/*
* As discussed on lkml, GENHD_FL_REMOVABLE should:
*
* - be set for removable media with permanent block devices
* - be unset for removable block devices with permanent media
*
* Since MMC block devices clearly fall under the second
* case, we do not set GENHD_FL_REMOVABLE. Userspace
* should use the block device creation/destruction hotplug
* messages to tell when the card is present.
*/
sprintf(md->disk->disk_name, "mmcblk%d", devidx);
blk_queue_hardsect_size(md->queue.queue, 512);
if (!mmc_card_sd(card) && mmc_card_blockaddr(card)) {
/*
* The EXT_CSD sector count is in number or 512 byte
* sectors.
*/
//设置磁盘容量，以扇区为单位
set_capacity(md->disk, card->ext_csd.sectors);
} else {
/*
* The CSD capacity field is in units of read_blkbits.
* set_capacity takes units of 512 bytes.
*/
set_capacity(md->disk,
card->csd.capacity << (card->csd.read_blkbits - 9));
}
return md;
err_putdisk:
put_disk(md->disk);
err_kfree:
kfree(md);
out:
return ERR_PTR(ret);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int
mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
{
struct mmc_command cmd;
int err;
/* Block-addressed cards ignore MMC_SET_BLOCKLEN. */
if (mmc_card_blockaddr(card))
return 0;
mmc_claim_host(card->host);
cmd.opcode = MMC_SET_BLOCKLEN;
cmd.arg = 512;
cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
err = mmc_wait_for_cmd(card->host, &cmd, 5);
mmc_release_host(card->host);
if (err) {
printk(KERN_ERR "%s: unable to set block size to %d: %d\n",
md->disk->disk_name, cmd.arg, err);
return -EINVAL;
}
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
//
/////
// 块驱动的初始化及磁盘分区的注册
static int mmc_blk_probe(struct mmc_card *card)
{
struct mmc_blk_data *md;
int err;
char cap_str[10];
/*
* Check that the card supports the command class(es) we need.
*/
if (!(card->csd.cmdclass & CCC_BLOCK_READ))
return -ENODEV;
//分配通用gendisk结构，块设备号，初始化请求队列，设置通用磁盘gendisk结构体的成员变量
md = mmc_blk_alloc(card);
if (IS_ERR(md))
return PTR_ERR(md);
//设置块长
err = mmc_blk_set_blksize(md, card);
if (err)
goto out;
string_get_size(get_capacity(md->disk) << 9, STRING_UNITS_2,
cap_str, sizeof(cap_str));
printk(KERN_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)" : "");
//关联mmc_card{} <--->mmc_blk_data{}
mmc_set_drvdata(card, md);
//激活磁盘设备，调用此函数后就可以立即对磁盘设备进行操作了
add_disk(md->disk);
return 0;
out:
mmc_blk_put(md);
return err;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static struct bus_type mmc_bus_type = {
.name = "mmc",
.dev_attrs = mmc_dev_attrs,
.match = mmc_bus_match,
.uevent = mmc_bus_uevent,
.probe = mmc_bus_probe,
.remove = mmc_bus_remove,
.suspend = mmc_bus_suspend,
.resume = mmc_bus_resume,
};
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int mmc_bus_probe(struct device *dev)
{
struct mmc_driver *drv = to_mmc_driver(dev->driver);
struct mmc_card *card = dev_to_mmc_card(dev);
//
//static struct mmc_driver mmc_driver = {
// .probe = mmc_blk_probe,
//此处调用的是mmc_blk_probe
return drv->probe(card);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static void mmc_blk_remove(struct mmc_card *card)
{
struct mmc_blk_data *md = mmc_get_drvdata(card);
if (md) {
/* Stop new requests from getting into the queue */
del_gendisk(md->disk);
/* Then flush out any already in there */
mmc_cleanup_queue(&md->queue);
mmc_blk_put(md);
}
mmc_set_drvdata(card, NULL);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifdef CONFIG_PM
static int mmc_blk_suspend(struct mmc_card *card, pm_message_t state)
{
struct mmc_blk_data *md = mmc_get_drvdata(card);
if (md) {
mmc_queue_suspend(&md->queue);
}
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
static int mmc_blk_resume(struct mmc_card *card)
{
struct mmc_blk_data *md = mmc_get_drvdata(card);
if (md) {
mmc_blk_set_blksize(md, card);
mmc_queue_resume(&md->queue);
}
return 0;
}
#else
#define mmc_blk_suspend NULL
#define mmc_blk_resume NULL
#endif
//////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* mmc_register_driver - register a media driver
* @drv: MMC media driver
*/
int mmc_register_driver(struct mmc_driver *drv)
{
drv->drv.bus = &mmc_bus_type;
////注册驱动
//mmc_driver设备驱动注册到驱动模型，挂在mmc_bus_type上面
return driver_register(&drv->drv);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* mmc_init_queue - initialise a queue structure.
* @mq: mmc queue
* @card: mmc card to attach this queue
* @lock: queue lock
*
* Initialise a MMC card request queue.
*/
int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
{
struct mmc_host *host = card->host;
u64 limit = BLK_BOUNCE_HIGH;
int ret;
if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
limit = *mmc_dev(host)->dma_mask;
mq->card = card;
//生成一个请求队列。其中rfn函数就是我们用户自己的request函数。
//生成的这个队列会放到gendisk结构里面，gendisk是来表示一个独立的磁盘设备或分区
mq->queue = blk_init_queue(mmc_request, lock);
if (!mq->queue)
return -ENOMEM;
mq->queue->queuedata = mq;
mq->req = NULL;
blk_queue_prep_rq(mq->queue, mmc_prep_request);
blk_queue_ordered(mq->queue, QUEUE_ORDERED_DRAIN, NULL);
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
#ifdef CONFIG_MMC_BLOCK_BOUNCE
if (host->max_hw_segs == 1) {
unsigned int bouncesz;
bouncesz = MMC_QUEUE_BOUNCESZ;
if (bouncesz > host->max_req_size)
bouncesz = host->max_req_size;
if (bouncesz > host->max_seg_size)
bouncesz = host->max_seg_size;
if (bouncesz > (host->max_blk_count * 512))
bouncesz = host->max_blk_count * 512;
if (bouncesz > 512) {
mq->bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
if (!mq->bounce_buf) {
printk(KERN_WARNING "%s: unable to "
"allocate bounce buffer\n",
mmc_card_name(card));
}
}
if (mq->bounce_buf) {
blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_ANY);
blk_queue_max_sectors(mq->queue, bouncesz / 512);
blk_queue_max_phys_segments(mq->queue, bouncesz / 512);
blk_queue_max_hw_segments(mq->queue, bouncesz / 512);
blk_queue_max_segment_size(mq->queue, bouncesz);
mq->sg = kmalloc(sizeof(struct scatterlist),
GFP_KERNEL);
if (!mq->sg) {
ret = -ENOMEM;
goto cleanup_queue;
}
sg_init_table(mq->sg, 1);
mq->bounce_sg = kmalloc(sizeof(struct scatterlist) *
bouncesz / 512, GFP_KERNEL);
if (!mq->bounce_sg) {
ret = -ENOMEM;
goto cleanup_queue;
}
sg_init_table(mq->bounce_sg, bouncesz / 512);
}
}
#endif
if (!mq->bounce_buf) {
blk_queue_bounce_limit(mq->queue, limit);
blk_queue_max_sectors(mq->queue,
min(host->max_blk_count, host->max_req_size / 512));
blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
blk_queue_max_segment_size(mq->queue, host->max_seg_size);
mq->sg = kmalloc(sizeof(struct scatterlist) *
host->max_phys_segs, GFP_KERNEL);
if (!mq->sg) {
ret = -ENOMEM;
goto cleanup_queue;
}
sg_init_table(mq->sg, host->max_phys_segs);
}
init_MUTEX(&mq->thread_sem);
//kthread_run是个宏定义,首先调用kthread_create()创建线程,
//如果创建成功,再调用wake_up_process()唤醒新创建的线程
mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd");
if (IS_ERR(mq->thread)) {
ret = PTR_ERR(mq->thread);
goto free_bounce_sg;
}
return 0;
free_bounce_sg:
if (mq->bounce_sg)
kfree(mq->bounce_sg);
mq->bounce_sg = NULL;
cleanup_queue:
if (mq->sg)
kfree(mq->sg);
mq->sg = NULL;
if (mq->bounce_buf)
kfree(mq->bounce_buf);
mq->bounce_buf = NULL;
blk_cleanup_queue(mq->queue);
return ret;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
static int mmc_queue_thread(void *d)
{
struct mmc_queue *mq = d;
struct request_queue *q = mq->queue;
current->flags |= PF_MEMALLOC;
down(&mq->thread_sem);
do {
struct request *req = NULL;
spin_lock_irq(q->queue_lock);
set_current_state(TASK_INTERRUPTIBLE);
if (!blk_queue_plugged(q))
req = elv_next_request(q);
mq->req = req;
spin_unlock_irq(q->queue_lock);
if (!req) {
if (kthread_should_stop()) {
set_current_state(TASK_RUNNING);
break;
}
up(&mq->thread_sem);
schedule();
down(&mq->thread_sem);
continue;
}
set_current_state(TASK_RUNNING);
//mmc_init_queue通过blk_init_queue(mmc_request, lock);绑定了请求处理函数mmc_request
//而mmc_request唤醒与mmc对应的内核线程来处理请求，
//与该线程对应的处理函数mmc_queue_thread()执行与mmc对应的 mq->issue_fn(mq, req);
//mmc_blk_probe函数-->mmc_blk_alloc(card);函数里
// md->queue.issue_fn = mmc_blk_issue_rq;
//对于存储设备而言， mq->issue_fn（）函数指向mmc_blk_issue_rq;函数
mq->issue_fn(mq, req);
} while (1);
up(&mq->thread_sem);
return 0;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
/*
* Generic MMC request handler. This is called for any queue on a
* particular host. When the host is not busy, we look for a request
* on any queue on this host, and attempt to issue it. This may
* not be the queue we were asked to process.
*/
static void mmc_request(struct request_queue *q)
{
struct mmc_queue *mq = q->queuedata;
struct request *req;
int ret;
if (!mq) {
printk(KERN_ERR "MMC: killing requests for dead queue\n");
while ((req = elv_next_request(q)) != NULL) {
do {
ret = __blk_end_request(req, -EIO,
blk_rq_cur_bytes(req));
} while (ret);
}
return;
}
//唤醒与mmc对应的内核线程来处理请求，
//与该线程对应的处理函数mmc_queue_thread()执行与mmc对应的 mq->issue_fn(mq, req);
if (!mq->req)
wake_up_process(mq->thread);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
struct mmc_queue {
struct mmc_card *card;
struct task_struct *thread;
struct semaphore thread_sem;
unsigned int flags;
struct request *req;
int (*issue_fn)(struct mmc_queue *, struct request *);
void *data;
struct request_queue *queue;
struct scatterlist *sg;
char *bounce_buf;
struct scatterlist *bounce_sg;
unsigned int bounce_sg_len;
};
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* blk_init_queue - prepare a request queue for use with a block device
* @rfn: The function to be called to process requests that have been
* placed on the queue.
* @lock: Request queue spin lock
*
* Description:
* If a block device wishes to use the standard request handling procedures,
* which sorts requests and coalesces adjacent requests, then it must
* call blk_init_queue(). The function @rfn will be called when there
* are requests on the queue that need to be processed. If the device
* supports plugging, then @rfn may not be called immediately when requests
* are available on the queue, but may be called at some time later instead.
* Plugged queues are generally unplugged when a buffer belonging to one
* of the requests on the queue is needed, or due to memory pressure.
*
* @rfn is not required, or even expected, to remove all requests off the
* queue, but only as many as it can handle at a time. If it does leave
* requests on the queue, it is responsible for arranging that the requests
* get dealt with eventually.
*
* The queue spin lock must be held while manipulating the requests on the
* request queue; this lock will be taken also from interrupt context, so irq
* disabling is needed for it.
*
* Function returns a pointer to the initialized request queue, or %NULL if
* it didn't succeed.
*
* Note:
* blk_init_queue() must be paired with a blk_cleanup_queue() call
* when the block device is deactivated (such as at module unload).
**/
struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
{
return blk_init_queue_node(rfn, lock, -1);
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
struct request_queue *
blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
{
struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
if (!q)
return NULL;
q->node = node_id;
if (blk_init_free_list(q)) {
kmem_cache_free(blk_requestq_cachep, q);
return NULL;
}
/*
* if caller didn't supply a lock, they get per-queue locking with
* our embedded lock
*/
if (!lock)
lock = &q->__queue_lock;
q->request_fn = rfn;//mmc_request
q->prep_rq_fn = NULL;
q->unplug_fn = generic_unplug_device;
q->queue_flags = (1 << QUEUE_FLAG_CLUSTER |
1 << QUEUE_FLAG_STACKABLE);
q->queue_lock = lock;
blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
blk_queue_make_request(q, __make_request);
blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
q->sg_reserved_size = INT_MAX;
blk_set_cmd_filter_defaults(&q->cmd_filter);
/*
* all done
*/
if (!elevator_init(q, NULL)) {
blk_queue_congestion_threshold(q);
return q;
}
blk_put_queue(q);
return NULL;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* blk_queue_make_request - define an alternate make_request function for a device
* @q: the request queue for the device to be affected
* @mfn: the alternate make_request function
*
* Description:
* The normal way for &struct bios to be passed to a device
* driver is for them to be collected into requests on a request
* queue, and then to allow the device driver to select requests
* off that queue when it is ready. This works well for many block
* devices. However some block devices (typically virtual devices
* such as md or lvm) do not benefit from the processing on the
* request queue, and are served best by having the requests passed
* directly to them. This can be achieved by providing a function
* to blk_queue_make_request().
*
* Caveat:
* The driver that does this *must* be able to deal appropriately
* with buffers in "highmemory". This can be accomplished by either calling
* __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
* blk_queue_bounce() to create a buffer in normal memory.
**/
void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
{
/*
* set defaults
*/
q->nr_requests = BLKDEV_MAX_RQ;
blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
q->make_request_fn = mfn;//__make_request
q->backing_dev_info.ra_pages =
(VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
q->backing_dev_info.state = 0;
q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
blk_queue_hardsect_size(q, 512);
blk_queue_dma_alignment(q, 511);
blk_queue_congestion_threshold(q);
q->nr_batching = BLK_BATCH_REQ;
q->unplug_thresh = 4; /* hmm */
q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
if (q->unplug_delay == 0)
q->unplug_delay = 1;
q->unplug_timer.function = blk_unplug_timeout;
q->unplug_timer.data = (unsigned long)q;
/*
* by default assume old behaviour and bounce for any highmem page
*/
blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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