build.c

基于linux-2.6.28的mtd驱动

/*
 * Copyright (c) International Business Machines Corp., 2006
 * Copyright (c) Nokia Corporation, 2007
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Author: Artem Bityutskiy (Битюцкий Артём),
 *         Frank Haverkamp
 */

/*
 * This file includes UBI initialization and building of UBI devices.
 *
 * When UBI is initialized, it attaches all the MTD devices specified as the
 * module load parameters or the kernel boot parameters. If MTD devices were
 * specified, UBI does not attach any MTD device, but it is possible to do
 * later using the "UBI control device".
 *
 * At the moment we only attach UBI devices by scanning, which will become a
 * bottleneck when flashes reach certain large size. Then one may improve UBI
 * and add other methods, although it does not seem to be easy to do.
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/stringify.h>
#include <linux/stat.h>
#include <linux/miscdevice.h>
#include <linux/log2.h>
#include <linux/kthread.h>
#include "ubi.h"

/* Maximum length of the 'mtd=' parameter */
#define MTD_PARAM_LEN_MAX 64

/**
 * struct mtd_dev_param - MTD device parameter description data structure.
 * @name: MTD device name or number string
 * @vid_hdr_offs: VID header offset
 */
struct mtd_dev_param {
	char name[MTD_PARAM_LEN_MAX];
	int vid_hdr_offs;
};

/* Numbers of elements set in the @mtd_dev_param array */
static int mtd_devs;

/* MTD devices specification parameters */
static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];

/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
struct class *ubi_class;

/* Slab cache for wear-leveling entries */
struct kmem_cache *ubi_wl_entry_slab;

/* UBI control character device */
static struct miscdevice ubi_ctrl_cdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "ubi_ctrl",
	.fops = &ubi_ctrl_cdev_operations,
};

/* All UBI devices in system */
static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];

/* Serializes UBI devices creations and removals */
DEFINE_MUTEX(ubi_devices_mutex);

/* Protects @ubi_devices and @ubi->ref_count */
static DEFINE_SPINLOCK(ubi_devices_lock);

/* "Show" method for files in '/<sysfs>/class/ubi/' */
static ssize_t ubi_version_show(struct class *class, char *buf)
{
	return sprintf(buf, "%d\n", UBI_VERSION);
}

/* UBI version attribute ('/<sysfs>/class/ubi/version') */
static struct class_attribute ubi_version =
	__ATTR(version, S_IRUGO, ubi_version_show, NULL);

static ssize_t dev_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf);

/* UBI device attributes (correspond to files in '/<sysfs>/class/ubi/ubiX') */
static struct device_attribute dev_eraseblock_size =
	__ATTR(eraseblock_size, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_avail_eraseblocks =
	__ATTR(avail_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_total_eraseblocks =
	__ATTR(total_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_volumes_count =
	__ATTR(volumes_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_max_ec =
	__ATTR(max_ec, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_reserved_for_bad =
	__ATTR(reserved_for_bad, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_bad_peb_count =
	__ATTR(bad_peb_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_max_vol_count =
	__ATTR(max_vol_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_min_io_size =
	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_bgt_enabled =
	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_mtd_num =
	__ATTR(mtd_num, S_IRUGO, dev_attribute_show, NULL);

/**
 * ubi_get_device - get UBI device.
 * @ubi_num: UBI device number
 *
 * This function returns UBI device description object for UBI device number
 * @ubi_num, or %NULL if the device does not exist. This function increases the
 * device reference count to prevent removal of the device. In other words, the
 * device cannot be removed if its reference count is not zero.
 */
struct ubi_device *ubi_get_device(int ubi_num)
{
	struct ubi_device *ubi;

	spin_lock(&ubi_devices_lock);
	ubi = ubi_devices[ubi_num];
	if (ubi) {
		ubi_assert(ubi->ref_count >= 0);
		ubi->ref_count += 1;
		get_device(&ubi->dev);
	}
	spin_unlock(&ubi_devices_lock);

	return ubi;
}

/**
 * ubi_put_device - drop an UBI device reference.
 * @ubi: UBI device description object
 */
void ubi_put_device(struct ubi_device *ubi)
{
	spin_lock(&ubi_devices_lock);
	ubi->ref_count -= 1;
	put_device(&ubi->dev);
	spin_unlock(&ubi_devices_lock);
}

/**
 * ubi_get_by_major - get UBI device by character device major number.
 * @major: major number
 *
 * This function is similar to 'ubi_get_device()', but it searches the device
 * by its major number.
 */
struct ubi_device *ubi_get_by_major(int major)
{
	int i;
	struct ubi_device *ubi;

	spin_lock(&ubi_devices_lock);
	for (i = 0; i < UBI_MAX_DEVICES; i++) {
		ubi = ubi_devices[i];
		if (ubi && MAJOR(ubi->cdev.dev) == major) {
			ubi_assert(ubi->ref_count >= 0);
			ubi->ref_count += 1;
			get_device(&ubi->dev);
			spin_unlock(&ubi_devices_lock);
			return ubi;
		}
	}
	spin_unlock(&ubi_devices_lock);

	return NULL;
}

/**
 * ubi_major2num - get UBI device number by character device major number.
 * @major: major number
 *
 * This function searches UBI device number object by its major number. If UBI
 * device was not found, this function returns -ENODEV, otherwise the UBI device
 * number is returned.
 */
int ubi_major2num(int major)
{
	int i, ubi_num = -ENODEV;

	spin_lock(&ubi_devices_lock);
	for (i = 0; i < UBI_MAX_DEVICES; i++) {
		struct ubi_device *ubi = ubi_devices[i];

		if (ubi && MAJOR(ubi->cdev.dev) == major) {
			ubi_num = ubi->ubi_num;
			break;
		}
	}
	spin_unlock(&ubi_devices_lock);

	return ubi_num;
}

/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
static ssize_t dev_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	ssize_t ret;
	struct ubi_device *ubi;

	/*
	 * The below code looks weird, but it actually makes sense. We get the
	 * UBI device reference from the contained 'struct ubi_device'. But it
	 * is unclear if the device was removed or not yet. Indeed, if the
	 * device was removed before we increased its reference count,
	 * 'ubi_get_device()' will return -ENODEV and we fail.
	 *
	 * Remember, 'struct ubi_device' is freed in the release function, so
	 * we still can use 'ubi->ubi_num'.
	 */
	ubi = container_of(dev, struct ubi_device, dev);
	ubi = ubi_get_device(ubi->ubi_num);
	if (!ubi)
		return -ENODEV;

	if (attr == &dev_eraseblock_size)
		ret = sprintf(buf, "%d\n", ubi->leb_size);
	else if (attr == &dev_avail_eraseblocks)
		ret = sprintf(buf, "%d\n", ubi->avail_pebs);
	else if (attr == &dev_total_eraseblocks)
		ret = sprintf(buf, "%d\n", ubi->good_peb_count);
	else if (attr == &dev_volumes_count)
		ret = sprintf(buf, "%d\n", ubi->vol_count - UBI_INT_VOL_COUNT);
	else if (attr == &dev_max_ec)
		ret = sprintf(buf, "%d\n", ubi->max_ec);
	else if (attr == &dev_reserved_for_bad)
		ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
	else if (attr == &dev_bad_peb_count)
		ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
	else if (attr == &dev_max_vol_count)
		ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
	else if (attr == &dev_min_io_size)
		ret = sprintf(buf, "%d\n", ubi->min_io_size);
	else if (attr == &dev_bgt_enabled)
		ret = sprintf(buf, "%d\n", ubi->thread_enabled);
	else if (attr == &dev_mtd_num)
		ret = sprintf(buf, "%d\n", ubi->mtd->index);
	else
		ret = -EINVAL;

	ubi_put_device(ubi);
	return ret;
}

/* Fake "release" method for UBI devices */
static void dev_release(struct device *dev) { }

/**
 * ubi_sysfs_init - initialize sysfs for an UBI device.
 * @ubi: UBI device description object
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int ubi_sysfs_init(struct ubi_device *ubi)
{
	int err;

	ubi->dev.release = dev_release;
	ubi->dev.devt = ubi->cdev.dev;
	ubi->dev.class = ubi_class;
	sprintf(&ubi->dev.bus_id[0], UBI_NAME_STR"%d", ubi->ubi_num);
	err = device_register(&ubi->dev);
	if (err)
		return err;

	err = device_create_file(&ubi->dev, &dev_eraseblock_size);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_avail_eraseblocks);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_total_eraseblocks);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_volumes_count);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_max_ec);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_reserved_for_bad);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_bad_peb_count);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_max_vol_count);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_min_io_size);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_bgt_enabled);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_mtd_num);
	return err;
}

/**
 * ubi_sysfs_close - close sysfs for an UBI device.
 * @ubi: UBI device description object
 */
static void ubi_sysfs_close(struct ubi_device *ubi)
{
	device_remove_file(&ubi->dev, &dev_mtd_num);
	device_remove_file(&ubi->dev, &dev_bgt_enabled);
	device_remove_file(&ubi->dev, &dev_min_io_size);
	device_remove_file(&ubi->dev, &dev_max_vol_count);
	device_remove_file(&ubi->dev, &dev_bad_peb_count);
	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
	device_remove_file(&ubi->dev, &dev_max_ec);
	device_remove_file(&ubi->dev, &dev_volumes_count);
	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
	device_remove_file(&ubi->dev, &dev_eraseblock_size);
	device_unregister(&ubi->dev);
}

/**
 * kill_volumes - destroy all volumes.
 * @ubi: UBI device description object
 */
static void kill_volumes(struct ubi_device *ubi)
{
	int i;

	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i])
			ubi_free_volume(ubi, ubi->volumes[i]);
}

/**
 * free_user_volumes - free all user volumes.
 * @ubi: UBI device description object
 *
 * Normally the volumes are freed at the release function of the volume device
 * objects. However, on error paths the volumes have to be freed before the
 * device objects have been initialized.
 */
static void free_user_volumes(struct ubi_device *ubi)
{
	int i;

	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i]) {
			kfree(ubi->volumes[i]->eba_tbl);
			kfree(ubi->volumes[i]);
		}
}

/**
 * uif_init - initialize user interfaces for an UBI device.
 * @ubi: UBI device description object
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure. Note, this function destroys all volumes if it failes.
 */
static int uif_init(struct ubi_device *ubi)
{
	int i, err, do_free = 0;
	dev_t dev;

	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);

	/*
	 * Major numbers for the UBI character devices are allocated
	 * dynamically. Major numbers of volume character devices are
	 * equivalent to ones of the corresponding UBI character device. Minor
	 * numbers of UBI character devices are 0, while minor numbers of
	 * volume character devices start from 1. Thus, we allocate one major
	 * number and ubi->vtbl_slots + 1 minor numbers.
	 */
	err = alloc_chrdev_region(&dev, 0, ubi->vtbl_slots + 1, ubi->ubi_name);
	if (err) {
		ubi_err("cannot register UBI character devices");
		return err;
	}

	ubi_assert(MINOR(dev) == 0);
	cdev_init(&ubi->cdev, &ubi_cdev_operations);
	dbg_gen("%s major is %u", ubi->ubi_name, MAJOR(dev));
	ubi->cdev.owner = THIS_MODULE;