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authorOlof Johansson <olof@lixom.net>2010-09-17 21:19:57 -0400
committerChris Ball <cjb@laptop.org>2010-10-25 09:28:46 +0800
commit5e71b7a64cb4c6cff75ca42b535d8227526ec592 (patch)
tree8bec2645c764c2711853ba4300d5eabcf80c3245
parent061c6c847eeb11743e489a16e907b41c6f9042b6 (diff)
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mmc: make number of mmcblk minors configurable
The old limit of number of minor numbers per mmcblk device was hardcoded at 8. This isn't enough for some of the more elaborate partitioning schemes, for example those used by Chrome OS. Since there might be a bunch of systems out there with static /dev contents that relies on the old numbering scheme, let's make it a build-time option with the default set to the previous 8. Also provide a boot/modprobe-time parameter to override the config default: mmcblk.perdev_minors. Signed-off-by: Olof Johansson <olof@lixom.net> Cc: Mandeep Baines <msb@chromium.org> Cc: <linux-mmc@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Chris Ball <cjb@laptop.org>
-rw-r--r--Documentation/devices.txt6
-rw-r--r--drivers/mmc/card/Kconfig17
-rw-r--r--drivers/mmc/card/block.c43
3 files changed, 54 insertions, 12 deletions
diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index c58abf1ccc71..170cc1e7e135 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt
@@ -2520,6 +2520,12 @@ Your cooperation is appreciated.
8 = /dev/mmcblk1 Second SD/MMC card
...
+ The start of next SD/MMC card can be configured with
+ CONFIG_MMC_BLOCK_MINORS, or overridden at boot/modprobe
+ time using the mmcblk.perdev_minors option. That would
+ bump the offset between each card to be the configured
+ value instead of the default 8.
+
179 char CCube DVXChip-based PCI products
0 = /dev/dvxirq0 First DVX device
1 = /dev/dvxirq1 Second DVX device
diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig
index 3f2a912659af..57e4416b9ef0 100644
--- a/drivers/mmc/card/Kconfig
+++ b/drivers/mmc/card/Kconfig
@@ -14,6 +14,23 @@ config MMC_BLOCK
mount the filesystem. Almost everyone wishing MMC support
should say Y or M here.
+config MMC_BLOCK_MINORS
+ int "Number of minors per block device"
+ range 4 256
+ default 8
+ help
+ Number of minors per block device. One is needed for every
+ partition on the disk (plus one for the whole disk).
+
+ Number of total MMC minors available is 256, so your number
+ of supported block devices will be limited to 256 divided
+ by this number.
+
+ Default is 8 to be backwards compatible with previous
+ hardwired device numbering.
+
+ If unsure, say 8 here.
+
config MMC_BLOCK_BOUNCE
bool "Use bounce buffer for simple hosts"
depends on MMC_BLOCK
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index a9970504cabb..217f82037fc1 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -43,15 +43,27 @@
#include "queue.h"
MODULE_ALIAS("mmc:block");
+#ifdef MODULE_PARAM_PREFIX
+#undef MODULE_PARAM_PREFIX
+#endif
+#define MODULE_PARAM_PREFIX "mmcblk."
+
+static DEFINE_MUTEX(block_mutex);
/*
- * max 8 partitions per card
+ * The defaults come from config options but can be overriden by module
+ * or bootarg options.
*/
-#define MMC_SHIFT 3
-#define MMC_NUM_MINORS (256 >> MMC_SHIFT)
+static int perdev_minors = CONFIG_MMC_BLOCK_MINORS;
-static DEFINE_MUTEX(block_mutex);
-static DECLARE_BITMAP(dev_use, MMC_NUM_MINORS);
+/*
+ * We've only got one major, so number of mmcblk devices is
+ * limited to 256 / number of minors per device.
+ */
+static int max_devices;
+
+/* 256 minors, so at most 256 separate devices */
+static DECLARE_BITMAP(dev_use, 256);
/*
* There is one mmc_blk_data per slot.
@@ -67,6 +79,9 @@ struct mmc_blk_data {
static DEFINE_MUTEX(open_lock);
+module_param(perdev_minors, int, 0444);
+MODULE_PARM_DESC(perdev_minors, "Minors numbers to allocate per device");
+
static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
{
struct mmc_blk_data *md;
@@ -88,10 +103,10 @@ static void mmc_blk_put(struct mmc_blk_data *md)
md->usage--;
if (md->usage == 0) {
int devmaj = MAJOR(disk_devt(md->disk));
- int devidx = MINOR(disk_devt(md->disk)) >> MMC_SHIFT;
+ int devidx = MINOR(disk_devt(md->disk)) / perdev_minors;
if (!devmaj)
- devidx = md->disk->first_minor >> MMC_SHIFT;
+ devidx = md->disk->first_minor / perdev_minors;
blk_cleanup_queue(md->queue.queue);
@@ -566,8 +581,8 @@ 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)
+ devidx = find_first_zero_bit(dev_use, max_devices);
+ if (devidx >= max_devices)
return ERR_PTR(-ENOSPC);
__set_bit(devidx, dev_use);
@@ -584,7 +599,7 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
*/
md->read_only = mmc_blk_readonly(card);
- md->disk = alloc_disk(1 << MMC_SHIFT);
+ md->disk = alloc_disk(perdev_minors);
if (md->disk == NULL) {
ret = -ENOMEM;
goto err_kfree;
@@ -601,7 +616,7 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
md->queue.data = md;
md->disk->major = MMC_BLOCK_MAJOR;
- md->disk->first_minor = devidx << MMC_SHIFT;
+ md->disk->first_minor = devidx * perdev_minors;
md->disk->fops = &mmc_bdops;
md->disk->private_data = md;
md->disk->queue = md->queue.queue;
@@ -670,7 +685,6 @@ static int mmc_blk_probe(struct mmc_card *card)
{
struct mmc_blk_data *md;
int err;
-
char cap_str[10];
/*
@@ -760,6 +774,11 @@ static int __init mmc_blk_init(void)
{
int res;
+ if (perdev_minors != CONFIG_MMC_BLOCK_MINORS)
+ pr_info("mmcblk: using %d minors per device\n", perdev_minors);
+
+ max_devices = 256 / perdev_minors;
+
res = register_blkdev(MMC_BLOCK_MAJOR, "mmc");
if (res)
goto out;