[PATCH] relayfs: add Documentation on relay files in other filesystems

[linux-2.6/mini2440.git] / drivers / mmc / mmc_block.c

/*
 * Block driver for media (i.e., flash cards)
 *
 * Copyright 2002 Hewlett-Packard Company
 *
 * Use consistent with the GNU GPL is permitted,
 * provided that this copyright notice is
 * preserved in its entirety in all copies and derived works.
 *
 * HEWLETT-PACKARD COMPANY MAKES NO WARRANTIES, EXPRESSED OR IMPLIED,
 * AS TO THE USEFULNESS OR CORRECTNESS OF THIS CODE OR ITS
 * FITNESS FOR ANY PARTICULAR PURPOSE.
 *
 * Many thanks to Alessandro Rubini and Jonathan Corbet!
 *
 * Author:  Andrew Christian
 *          28 May 2002
 */
#include <linux/moduleparam.h>
#include <linux/module.h>
#include <linux/init.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/hdreg.h>
#include <linux/kdev_t.h>
#include <linux/blkdev.h>
#include <linux/devfs_fs_kernel.h>

#include <linux/mmc/card.h>
#include <linux/mmc/protocol.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#include "mmc_queue.h"

/*
 * max 8 partitions per card
 */
#define MMC_SHIFT       3

static int major;

/*
 * 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    block_bits;
        unsigned int    read_only;
};

static DECLARE_MUTEX(open_lock);

static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
{
        struct mmc_blk_data *md;

        down(&open_lock);
        md = disk->private_data;
        if (md && md->usage == 0)
                md = NULL;
        if (md)
                md->usage++;
        up(&open_lock);

        return md;
}

static void mmc_blk_put(struct mmc_blk_data *md)
{
        down(&open_lock);
        md->usage--;
        if (md->usage == 0) {
                put_disk(md->disk);
                mmc_cleanup_queue(&md->queue);
                kfree(md);
        }
        up(&open_lock);
}

static int mmc_blk_open(struct inode *inode, struct file *filp)
{
        struct mmc_blk_data *md;
        int ret = -ENXIO;

        md = mmc_blk_get(inode->i_bdev->bd_disk);
        if (md) {
                if (md->usage == 2)
                        check_disk_change(inode->i_bdev);
                ret = 0;

                if ((filp->f_mode & FMODE_WRITE) && md->read_only)
                        ret = -EROFS;
        }

        return ret;
}

static int mmc_blk_release(struct inode *inode, struct file *filp)
{
        struct mmc_blk_data *md = inode->i_bdev->bd_disk->private_data;

        mmc_blk_put(md);
        return 0;
}

static int
mmc_blk_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct block_device *bdev = inode->i_bdev;

        if (cmd == HDIO_GETGEO) {
                struct hd_geometry geo;

                memset(&geo, 0, sizeof(struct hd_geometry));

                geo.cylinders   = get_capacity(bdev->bd_disk) / (4 * 16);
                geo.heads       = 4;
                geo.sectors     = 16;
                geo.start       = get_start_sect(bdev);

                return copy_to_user((void __user *)arg, &geo, sizeof(geo))
                        ? -EFAULT : 0;
        }

        return -ENOTTY;
}

static struct block_device_operations mmc_bdops = {
        .open                   = mmc_blk_open,
        .release                = mmc_blk_release,
        .ioctl                  = mmc_blk_ioctl,
        .owner                  = THIS_MODULE,
};

struct mmc_blk_request {
        struct mmc_request      mrq;
        struct mmc_command      cmd;
        struct mmc_command      stop;
        struct mmc_data         data;
};

static int mmc_blk_prep_rq(struct mmc_queue *mq, struct request *req)
{
        struct mmc_blk_data *md = mq->data;
        int stat = BLKPREP_OK;

        /*
         * If we have no device, we haven't finished initialising.
         */
        if (!md || !mq->card) {
                printk(KERN_ERR "%s: killing request - no device/host\n",
                       req->rq_disk->disk_name);
                stat = BLKPREP_KILL;
        }

        return stat;
}

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;
        int ret;

        if (mmc_card_claim_host(card))
                goto cmd_err;

        do {
                struct mmc_blk_request brq;
                struct mmc_command cmd;

                memset(&brq, 0, sizeof(struct mmc_blk_request));
                brq.mrq.cmd = &brq.cmd;
                brq.mrq.data = &brq.data;

                brq.cmd.arg = req->sector << 9;
                brq.cmd.flags = MMC_RSP_R1;
                brq.data.timeout_ns = card->csd.tacc_ns * 10;
                brq.data.timeout_clks = card->csd.tacc_clks * 10;
                brq.data.blksz_bits = md->block_bits;
                brq.data.blocks = req->nr_sectors >> (md->block_bits - 9);
                brq.stop.opcode = MMC_STOP_TRANSMISSION;
                brq.stop.arg = 0;
                brq.stop.flags = MMC_RSP_R1B;

                if (rq_data_dir(req) == READ) {
                        brq.cmd.opcode = brq.data.blocks > 1 ? MMC_READ_MULTIPLE_BLOCK : MMC_READ_SINGLE_BLOCK;
                        brq.data.flags |= MMC_DATA_READ;
                } else {
                        brq.cmd.opcode = MMC_WRITE_BLOCK;
                        brq.data.flags |= MMC_DATA_WRITE;
                        brq.data.blocks = 1;
                }
                brq.mrq.stop = brq.data.blocks > 1 ? &brq.stop : NULL;

                brq.data.sg = mq->sg;
                brq.data.sg_len = blk_rq_map_sg(req->q, req, brq.data.sg);

                mmc_wait_for_req(card->host, &brq.mrq);
                if (brq.cmd.error) {
                        printk(KERN_ERR "%s: error %d sending read/write command\n",
                               req->rq_disk->disk_name, brq.cmd.error);
                        goto cmd_err;
                }

                if (brq.data.error) {
                        printk(KERN_ERR "%s: error %d transferring data\n",
                               req->rq_disk->disk_name, brq.data.error);
                        goto cmd_err;
                }

                if (brq.stop.error) {
                        printk(KERN_ERR "%s: error %d sending stop command\n",
                               req->rq_disk->disk_name, brq.stop.error);
                        goto cmd_err;
                }

                do {
                        int err;

                        cmd.opcode = MMC_SEND_STATUS;
                        cmd.arg = card->rca << 16;
                        cmd.flags = MMC_RSP_R1;
                        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;
                        }
                } while (!(cmd.resp[0] & R1_READY_FOR_DATA));

#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

                /*
                 * A block was successfully transferred.
                 */
                spin_lock_irq(&md->lock);
                ret = end_that_request_chunk(req, 1, brq.data.bytes_xfered);
                if (!ret) {
                        /*
                         * The whole request completed successfully.
                         */
                        add_disk_randomness(req->rq_disk);
                        blkdev_dequeue_request(req);
                        end_that_request_last(req, 1);
                }
                spin_unlock_irq(&md->lock);
        } while (ret);

        mmc_card_release_host(card);

        return 1;

 cmd_err:
        mmc_card_release_host(card);

        /*
         * This is a little draconian, but until we get proper
         * error handling sorted out here, its the best we can
         * do - especially as some hosts have no idea how much
         * data was transferred before the error occurred.
         */
        spin_lock_irq(&md->lock);
        do {
                ret = end_that_request_chunk(req, 0,
                                req->current_nr_sectors << 9);
        } while (ret);

        add_disk_randomness(req->rq_disk);
        blkdev_dequeue_request(req);
        end_that_request_last(req, 0);
        spin_unlock_irq(&md->lock);

        return 0;
}

#define MMC_NUM_MINORS  (256 >> MMC_SHIFT)

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;
        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 = kmalloc(sizeof(struct mmc_blk_data), GFP_KERNEL);
        if (!md) {
                ret = -ENOMEM;
                goto out;
        }

        memset(md, 0, sizeof(struct mmc_blk_data));

        /*
         * Set the read-only status based on the supported commands
         * and the write protect switch.
         */
        md->read_only = mmc_blk_readonly(card);

        /*
         * 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;
                }
        }

        /*
         * 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;
        }

        md->disk = alloc_disk(1 << MMC_SHIFT);
        if (md->disk == NULL) {
                ret = -ENOMEM;
                goto err_kfree;
        }

        spin_lock_init(&md->lock);
        md->usage = 1;

        ret = mmc_init_queue(&md->queue, card, &md->lock);
        if (ret)
                goto err_putdisk;

        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;

        /*
         * 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
mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
{
        struct mmc_command cmd;
        int err;

        mmc_card_claim_host(card);
        cmd.opcode = MMC_SET_BLOCKLEN;
        cmd.arg = 1 << md->block_bits;
        cmd.flags = MMC_RSP_R1;
        err = mmc_wait_for_cmd(card->host, &cmd, 5);
        mmc_card_release_host(card);

        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;
}

static int mmc_blk_probe(struct mmc_card *card)
{
        struct mmc_blk_data *md;
        int err;

        /*
         * Check that the card supports the command class(es) we need.
         */
        if (!(card->csd.cmdclass & CCC_BLOCK_READ))
                return -ENODEV;

        md = mmc_blk_alloc(card);
        if (IS_ERR(md))
                return PTR_ERR(md);

        err = mmc_blk_set_blksize(md, card);
        if (err)
                goto out;

        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, md->read_only ? "(ro)" : "");

        mmc_set_drvdata(card, md);
        add_disk(md->disk);
        return 0;

 out:
        mmc_blk_put(md);

        return err;
}

static void mmc_blk_remove(struct mmc_card *card)
{
        struct mmc_blk_data *md = mmc_get_drvdata(card);

        if (md) {
                int devidx;

                del_gendisk(md->disk);

                /*
                 * I think this is needed.
                 */
                md->disk->queue = NULL;

                devidx = md->disk->first_minor >> MMC_SHIFT;
                __clear_bit(devidx, dev_use);

                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

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 int __init mmc_blk_init(void)
{
        int res = -ENOMEM;

        res = register_blkdev(major, "mmc");
        if (res < 0) {
                printk(KERN_WARNING "Unable to get major %d for MMC media: %d\n",
                       major, res);
                goto out;
        }
        if (major == 0)
                major = res;

        devfs_mk_dir("mmc");
        return mmc_register_driver(&mmc_driver);

 out:
        return res;
}

static void __exit mmc_blk_exit(void)
{
        mmc_unregister_driver(&mmc_driver);
        devfs_remove("mmc");
        unregister_blkdev(major, "mmc");
}

module_init(mmc_blk_init);
module_exit(mmc_blk_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Multimedia Card (MMC) block device driver");

module_param(major, int, 0444);
MODULE_PARM_DESC(major, "specify the major device number for MMC block driver");