Commit a6f6c96b authored by Russell King's avatar Russell King Committed by Russell King

[MMC] Improve MMC card block size selection

Select a block size for IO based on the read and write block size
combinations, and whether the card supports partial block reads
and/or partial block writes.

If we are able to satisfy block reads but not block writes, mark
the device read only.
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 88026842
......@@ -550,6 +550,11 @@ static void mmc_decode_csd(struct mmc_card *card)
csd->capacity = (1 + m) << (e + 2);
csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
} else {
/*
* We only understand CSD structure v1.1 and v1.2.
......@@ -579,6 +584,11 @@ static void mmc_decode_csd(struct mmc_card *card)
csd->capacity = (1 + m) << (e + 2);
csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
}
}
......
......@@ -54,6 +54,7 @@ struct mmc_blk_data {
unsigned int usage;
unsigned int block_bits;
unsigned int read_only;
};
static DECLARE_MUTEX(open_lock);
......@@ -85,12 +86,6 @@ static void mmc_blk_put(struct mmc_blk_data *md)
up(&open_lock);
}
static inline int mmc_blk_readonly(struct mmc_card *card)
{
return mmc_card_readonly(card) ||
!(card->csd.cmdclass & CCC_BLOCK_WRITE);
}
static int mmc_blk_open(struct inode *inode, struct file *filp)
{
struct mmc_blk_data *md;
......@@ -102,8 +97,7 @@ static int mmc_blk_open(struct inode *inode, struct file *filp)
check_disk_change(inode->i_bdev);
ret = 0;
if ((filp->f_mode & FMODE_WRITE) &&
mmc_blk_readonly(md->queue.card))
if ((filp->f_mode & FMODE_WRITE) && md->read_only)
ret = -EROFS;
}
......@@ -299,6 +293,12 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
static unsigned long dev_use[MMC_NUM_MINORS/(8*sizeof(unsigned long))];
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;
......@@ -310,64 +310,121 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
__set_bit(devidx, dev_use);
md = kmalloc(sizeof(struct mmc_blk_data), GFP_KERNEL);
if (md) {
memset(md, 0, sizeof(struct mmc_blk_data));
if (!md) {
ret = -ENOMEM;
goto out;
}
md->disk = alloc_disk(1 << MMC_SHIFT);
if (md->disk == NULL) {
kfree(md);
md = ERR_PTR(-ENOMEM);
goto out;
}
memset(md, 0, sizeof(struct mmc_blk_data));
spin_lock_init(&md->lock);
md->usage = 1;
/*
* Set the read-only status based on the supported commands
* and the write protect switch.
*/
md->read_only = mmc_blk_readonly(card);
ret = mmc_init_queue(&md->queue, card, &md->lock);
if (ret) {
put_disk(md->disk);
kfree(md);
md = ERR_PTR(ret);
goto out;
/*
* Figure out a workable block size. MMC cards have:
* - two block sizes, one for read and one for write.
* - may support partial reads and/or writes
* (allows block sizes smaller than specified)
*/
md->block_bits = card->csd.read_blkbits;
if (card->csd.write_blkbits != card->csd.read_blkbits) {
if (card->csd.write_blkbits < card->csd.read_blkbits &&
card->csd.read_partial) {
/*
* write block size is smaller than read block
* size, but we support partial reads, so choose
* the smaller write block size.
*/
md->block_bits = card->csd.write_blkbits;
} else if (card->csd.write_blkbits > card->csd.read_blkbits &&
card->csd.write_partial) {
/*
* read block size is smaller than write block
* size, but we support partial writes. Use read
* block size.
*/
} else {
/*
* We don't support this configuration for writes.
*/
printk(KERN_ERR "%s: unable to select block size for "
"writing (rb%u wb%u rp%u wp%u)\n",
md->disk->disk_name,
1 << card->csd.read_blkbits,
1 << card->csd.write_blkbits,
card->csd.read_partial,
card->csd.write_partial);
md->read_only = 1;
}
md->queue.prep_fn = mmc_blk_prep_rq;
md->queue.issue_fn = mmc_blk_issue_rq;
md->queue.data = md;
}
md->disk->major = 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;
/*
* Refuse to allow block sizes smaller than 512 bytes.
*/
if (md->block_bits < 9) {
printk(KERN_ERR "%s: unable to support block size %u\n",
mmc_card_id(card), 1 << md->block_bits);
ret = -EINVAL;
goto err_kfree;
}
/*
* 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.
*/
md->disk = alloc_disk(1 << MMC_SHIFT);
if (md->disk == NULL) {
ret = -ENOMEM;
goto err_kfree;
}
sprintf(md->disk->disk_name, "mmcblk%d", devidx);
sprintf(md->disk->devfs_name, "mmc/blk%d", devidx);
spin_lock_init(&md->lock);
md->usage = 1;
md->block_bits = card->csd.read_blkbits;
ret = mmc_init_queue(&md->queue, card, &md->lock);
if (ret)
goto err_putdisk;
blk_queue_hardsect_size(md->queue.queue, 1 << md->block_bits);
md->queue.prep_fn = mmc_blk_prep_rq;
md->queue.issue_fn = mmc_blk_issue_rq;
md->queue.data = md;
/*
* 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));
}
out:
md->disk->major = 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);
sprintf(md->disk->devfs_name, "mmc/blk%d", devidx);
blk_queue_hardsect_size(md->queue.queue, 1 << md->block_bits);
/*
* 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
......@@ -403,12 +460,6 @@ static int mmc_blk_probe(struct mmc_card *card)
if (!(card->csd.cmdclass & CCC_BLOCK_READ))
return -ENODEV;
if (card->csd.read_blkbits < 9) {
printk(KERN_WARNING "%s: read blocksize too small (%u)\n",
mmc_card_id(card), 1 << card->csd.read_blkbits);
return -ENODEV;
}
md = mmc_blk_alloc(card);
if (IS_ERR(md))
return PTR_ERR(md);
......@@ -419,7 +470,7 @@ static int mmc_blk_probe(struct mmc_card *card)
printk(KERN_INFO "%s: %s %s %luKiB %s\n",
md->disk->disk_name, mmc_card_id(card), mmc_card_name(card),
get_capacity(md->disk) >> 1, mmc_blk_readonly(card)?"(ro)":"");
get_capacity(md->disk) >> 1, md->read_only ? "(ro)" : "");
mmc_set_drvdata(card, md);
add_disk(md->disk);
......
......@@ -30,7 +30,12 @@ struct mmc_csd {
unsigned int tacc_ns;
unsigned int max_dtr;
unsigned int read_blkbits;
unsigned int write_blkbits;
unsigned int capacity;
unsigned int read_partial:1,
read_misalign:1,
write_partial:1
write_misalign:1;
};
struct sd_scr {
......
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