drivers/rtc/rtc-test.c


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/*
 * An RTC test device/driver
 * Copyright (C) 2005 Tower Technologies
 * Author: Alessandro Zummo <a.zummo@towertech.it>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>

static struct platform_device *test0 = NULL, *test1 = NULL;

static int test_rtc_read_alarm(struct device *dev,
	struct rtc_wkalrm *alrm)
{
	return 0;
}

static int test_rtc_set_alarm(struct device *dev,
	struct rtc_wkalrm *alrm)
{
	return 0;
}

static int test_rtc_read_time(struct device *dev,
	struct rtc_time *tm)
{
	rtc_time_to_tm(get_seconds(), tm);
	return 0;
}

static int test_rtc_set_mmss(struct device *dev, unsigned long secs)
{
	dev_info(dev, "%s, secs = %lu\n", __func__, secs);
	return 0;
}

static int test_rtc_proc(struct device *dev, struct seq_file *seq)
{
	struct platform_device *plat_dev = to_platform_device(dev);

	seq_printf(seq, "test\t\t: yes\n");
	seq_printf(seq, "id\t\t: %d\n", plat_dev->id);

	return 0;
}

static int test_rtc_ioctl(struct device *dev, unsigned int cmd,
	unsigned long arg)
{
	/* We do support interrupts, they're generated
	 * using the sysfs interface.
	 */
	switch (cmd) {
	case RTC_PIE_ON:
	case RTC_PIE_OFF:
	case RTC_UIE_ON:
	case RTC_UIE_OFF:
	case RTC_AIE_ON:
	case RTC_AIE_OFF:
		return 0;

	default:
		return -ENOIOCTLCMD;
	}
}

static const struct rtc_class_ops test_rtc_ops = {
	.proc = test_rtc_proc,
	.read_time = test_rtc_read_time,
	.read_alarm = test_rtc_read_alarm,
	.set_alarm = test_rtc_set_alarm,
	.set_mmss = test_rtc_set_mmss,
	.ioctl = test_rtc_ioctl,
};

static ssize_t test_irq_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", 42);
}
static ssize_t test_irq_store(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t count)
{
	int retval;
	struct platform_device *plat_dev = to_platform_device(dev);
	struct rtc_device *rtc = platform_get_drvdata(plat_dev);

	retval = count;
	local_irq_disable();
	if (strncmp(buf, "tick", 4) == 0)
		rtc_update_irq(rtc, 1, RTC_PF | RTC_IRQF);
	else if (strncmp(buf, "alarm", 5) == 0)
		rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);
	else if (strncmp(buf, "update", 6) == 0)
		rtc_update_irq(rtc, 1, RTC_UF | RTC_IRQF);
	else
		retval = -EINVAL;
	local_irq_enable();

	return retval;
}
static DEVICE_ATTR(irq, S_IRUGO | S_IWUSR, test_irq_show, test_irq_store);

static int test_probe(struct platform_device *plat_dev)
{
	int err;
	struct rtc_device *rtc = rtc_device_register("test", &plat_dev->dev,
						&test_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc)) {
		err = PTR_ERR(rtc);
		return err;
	}

	err = device_create_file(&plat_dev->dev, &dev_attr_irq);
	if (err)
		goto err;

	platform_set_drvdata(plat_dev, rtc);

	return 0;

err:
	rtc_device_unregister(rtc);
	return err;
}

static int __devexit test_remove(struct platform_device *plat_dev)
{
	struct rtc_device *rtc = platform_get_drvdata(plat_dev);

	rtc_device_unregister(rtc);
	device_remove_file(&plat_dev->dev, &dev_attr_irq);

	return 0;
}

static struct platform_driver test_driver = {
	.probe	= test_probe,
	.remove = __devexit_p(test_remove),
	.driver = {
		.name = "rtc-test",
		.owner = THIS_MODULE,
	},
};

static int __init test_init(void)
{
	int err;

	if ((err = platform_driver_register(&test_driver)))
		return err;

	if ((test0 = platform_device_alloc("rtc-test", 0)) == NULL) {
		err = -ENOMEM;
		goto exit_driver_unregister;
	}

	if ((test1 = platform_device_alloc("rtc-test", 1)) == NULL) {
		err = -ENOMEM;
		goto exit_free_test0;
	}

	if ((err = platform_device_add(test0)))
		goto exit_free_test1;

	if ((err = platform_device_add(test1)))
		goto exit_device_unregister;

	return 0;

exit_device_unregister:
	platform_device_unregister(test0);

exit_free_test1:
	platform_device_put(test1);

exit_free_test0:
	platform_device_put(test0);

exit_driver_unregister:
	platform_driver_unregister(&test_driver);
	return err;
}

static void __exit test_exit(void)
{
	platform_device_unregister(test0);
	platform_device_unregister(test1);
	platform_driver_unregister(&test_driver);
}

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("RTC test driver/device");
MODULE_LICENSE("GPL");

module_init(test_init);
module_exit(test_exit);
/*
 *  linux/fs/super.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  super.c contains code to handle: - mount structures
 *                                   - super-block tables
 *                                   - filesystem drivers list
 *                                   - mount system call
 *                                   - umount system call
 *                                   - ustat system call
 *
 * GK 2/5/95  -  Changed to support mounting the root fs via NFS
 *
 *  Added kerneld support: Jacques Gelinas and Bjorn Ekwall
 *  Added change_root: Werner Almesberger & Hans Lermen, Feb '96
 *  Added options to /proc/mounts:
 *    Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
 *  Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
 *  Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
 */

#include <linux/export.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/writeback.h>		/* for the emergency remount stuff */
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/backing-dev.h>
#include <linux/rculist_bl.h>
#include <linux/cleancache.h>
#include <linux/fsnotify.h>
#include <linux/lockdep.h>
#include "internal.h"


LIST_HEAD(super_blocks);
DEFINE_SPINLOCK(sb_lock);

static char *sb_writers_name[SB_FREEZE_LEVELS] = {
	"sb_writers",
	"sb_pagefaults",
	"sb_internal",
};

/*
 * One thing we have to be careful of with a per-sb shrinker is that we don't
 * drop the last active reference to the superblock from within the shrinker.
 * If that happens we could trigger unregistering the shrinker from within the
 * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we
 * take a passive reference to the superblock to avoid this from occurring.
 */
static unsigned long super_cache_scan(struct shrinker *shrink,
				      struct shrink_control *sc)
{
	struct super_block *sb;
	long	fs_objects = 0;
	long	total_objects;
	long	freed = 0;
	long	dentries;
	long	inodes;

	sb = container_of(shrink, struct super_block, s_shrink);

	/*
	 * Deadlock avoidance.  We may hold various FS locks, and we don't want
	 * to recurse into the FS that called us in clear_inode() and friends..
	 */
	if (!(sc->gfp_mask & __GFP_FS))
		return SHRINK_STOP;

	if (!grab_super_passive(sb))
		return SHRINK_STOP;

	if (sb->s_op->nr_cached_objects)
		fs_objects = sb->s_op->nr_cached_objects(sb, sc->nid);

	inodes = list_lru_count_node(&sb->s_inode_lru, sc->nid);
	dentries = list_lru_count_node(&sb->s_dentry_lru, sc->nid);
	total_objects = dentries + inodes + fs_objects + 1;
	if (!total_objects)
		total_objects = 1;

	/* proportion the scan between the caches */
	dentries = mult_frac(sc->nr_to_scan, dentries, total_objects);
	inodes = mult_frac(sc->nr_to_scan, inodes, total_objects);

	/*
	 * prune the dcache first as the icache is pinned by it, then
	 * prune the icache, followed by the filesystem specific caches
	 */
	freed = prune_dcache_sb(sb, dentries, sc->nid);
	freed += prune_icache_sb(sb, inodes, sc->nid);

	if (fs_objects) {
		fs_objects = mult_frac(sc->nr_to_scan, fs_objects,
								total_objects);
		freed += sb->s_op->free_cached_objects(sb, fs_objects,
						       sc->nid);
	}

	drop_super(sb);
	return freed;
}

static unsigned long super_cache_count(struct shrinker *shrink,
				       struct shrink_control *sc)
{
	struct super_block *sb;
	long	total_objects = 0;

	sb = container_of(shrink, struct super_block, s_shrink);

	/*
	 * Don't call grab_super_passive as it is a potential
	 * scalability bottleneck. The counts could get updated
	 * between super_cache_count and super_cache_scan anyway.
	 * Call to super_cache_count with shrinker_rwsem held
	 * ensures the safety of call to list_lru_count_node() and
	 * s_op->nr_cached_objects().
	 */
	if (sb->s_op && sb->s_op->nr_cached_objects)
		total_objects = sb->s_op->nr_cached_objects(sb,
						 sc->nid);

	total_objects += list_lru_count_node(&sb->s_dentry_lru,
						 sc->nid);
	total_objects += list_lru_count_node(&sb->s_inode_lru,
						 sc->nid);

	total_objects = vfs_pressure_ratio(total_objects);
	return total_objects;
}

/**
 *	destroy_super	-	frees a superblock
 *	@s: superblock to free
 *
 *	Frees a superblock.
 */
static void destroy_super(struct super_block *s)
{
	int i;
	list_lru_destroy(&s->s_dentry_lru);
	list_lru_destroy(&s->s_inode_lru);
	for (i = 0; i < SB_FREEZE_LEVELS; i++)
		percpu_counter_destroy(&s->s_writers.counter[i]);
	security_sb_free(s);
	WARN_ON(!list_empty(&s->s_mounts));
	kfree(s->s_subtype);
	kfree(s->s_options);
	kfree_rcu(s, rcu);
}

/**
 *	alloc_super	-	create new superblock
 *	@type:	filesystem type superblock should belong to
 *	@flags: the mount flags
 *
 *	Allocates and initializes a new &struct super_block.  alloc_super()
 *	returns a pointer new superblock or %NULL if allocation had failed.
 */
static struct super_block *alloc_super(struct file_system_type *type, int flags)
{
	struct super_block *s = kzalloc(sizeof(struct super_block),  GFP_USER);
	static const struct super_operations default_op;
	int i;

	if (!s)
		return NULL;

	INIT_LIST_HEAD(&s->s_mounts);

	if (security_sb_alloc(s))
		goto fail;

	for (i = 0; i < SB_FREEZE_LEVELS; i++) {
		if (percpu_counter_init(&s->s_writers.counter[i], 0,
					GFP_KERNEL) < 0)
			goto fail;
		lockdep_init_map(&s->s_writers.lock_map[i], sb_writers_name[i],
				 &type->s_writers_key[i], 0);
	}
	init_waitqueue_head(&s->s_writers.wait);
	init_waitqueue_head(&s->s_writers.wait_unfrozen);
	s->s_flags = flags;
	s->s_bdi = &default_backing_dev_info;
	INIT_HLIST_NODE(&s->s_instances);
	INIT_HLIST_BL_HEAD(&s->s_anon);
	INIT_LIST_HEAD(&s->s_inodes);

	if (list_lru_init(&s->s_dentry_lru))
		goto fail;
	if (list_lru_init(&s->s_inode_lru))
		goto fail;

	init_rwsem(&s->s_umount);
	lockdep_set_class(&s->s_umount, &type->s_umount_key);
	/*
	 * sget() can have s_umount recursion.
	 *
	 * When it cannot find a suitable sb, it allocates a new
	 * one (this one), and tries again to find a suitable old
	 * one.
	 *
	 * In case that succeeds, it will acquire the s_umount
	 * lock of the old one. Since these are clearly distrinct
	 * locks, and this object isn't exposed yet, there's no
	 * risk of deadlocks.
	 *
	 * Annotate this by putting this lock in a different
	 * subclass.
	 */
	down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
	s->s_count = 1;
	atomic_set(&s->s_active, 1);
	mutex_init(&s->s_vfs_rename_mutex);
	lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
	mutex_init(&s->s_dquot.dqio_mutex);
	mutex_init(&s->s_dquot.dqonoff_mutex);
	s->s_maxbytes = MAX_NON_LFS;
	s->s_op = &default_op;
	s->s_time_gran = 1000000000;
	s->cleancache_poolid = -1;

	s->s_shrink.seeks = DEFAULT_SEEKS;
	s->s_shrink.scan_objects = super_cache_scan;
	s->s_shrink.count_objects = super_cache_count;
	s->s_shrink.batch = 1024;
	s->s_shrink.flags = SHRINKER_NUMA_AWARE;
	return s;

fail:
	destroy_super(s);
	return NULL;
}

/* Superblock refcounting  */

/*
 * Drop a superblock's refcount.  The caller must hold sb_lock.
 */
static void __put_super(struct super_block *sb)
{
	if (!--sb->s_count) {
		list_del_init(&sb->s_list);
		destroy_super(sb);
	}
}

/**
 *	put_super	-	drop a temporary reference to superblock
 *	@sb: superblock in question
 *
 *	Drops a temporary reference, frees superblock if there's no
 *	references left.
 */
static void put_super(struct super_block *sb)
{
	spin_lock(&sb_lock);
	__put_super(sb);
	spin_unlock(&sb_lock);
}


/**
 *	deactivate_locked_super	-	drop an active reference to superblock
 *	@s: superblock to deactivate
 *
 *	Drops an active reference to superblock, converting it into a temprory
 *	one if there is no other active references left.  In that case we
 *	tell fs driver to shut it down and drop the temporary reference we
 *	had just acquired.
 *
 *	Caller holds exclusive lock on superblock; that lock is released.
 */
void deactivate_locked_super(struct super_block *s)
{
	struct file_system_type *fs = s->s_type;
	if (atomic_dec_and_test(&s->s_active)) {
		cleancache_invalidate_fs(s);
		unregister_shrinker(&s->s_shrink);
		fs->kill_sb(s);

		put_filesystem(fs);
		put_super(s);
	} else {
		up_write(&s->s_umount);
	}
}

EXPORT_SYMBOL(deactivate_locked_super);

/**
 *	deactivate_super	-	drop an active reference to superblock
 *	@s: superblock to deactivate
 *
 *	Variant of deactivate_locked_super(), except that superblock is *not*
 *	locked by caller.  If we are going to drop the final active reference,
 *	lock will be acquired prior to that.
 */
void deactivate_super(struct super_block *s)
{
        if (!atomic_add_unless(&s->s_active, -1, 1)) {
		down_write(&s->s_umount);
		deactivate_locked_super(s);
	}
}

EXPORT_SYMBOL(deactivate_super);

/**
 *	grab_super - acquire an active reference
 *	@s: reference we are trying to make active
 *
 *	Tries to acquire an active reference.  grab_super() is used when we
 * 	had just found a superblock in super_blocks or fs_type->fs_supers
 *	and want to turn it into a full-blown active reference.  grab_super()
 *	is called with sb_lock held and drops it.  Returns 1 in case of
 *	success, 0 if we had failed (superblock contents was already dead or
 *	dying when grab_super() had been called).  Note that this is only
 *	called for superblocks not in rundown mode (== ones still on ->fs_supers
 *	of their type), so increment of ->s_count is OK here.
 */
static int grab_super(struct super_block *s) __releases(sb_lock)
{
	s->s_count++;
	spin_unlock(&sb_lock);
	down_write(&s->s_umount);
	if ((s->s_flags & MS_BORN) && atomic_inc_not_zero(&s->s_active)) {
		put_super(s);
		return 1;
	}
	up_write(&s->s_umount);
	put_super(s);
	return 0;
}

/*
 *	grab_super_passive - acquire a passive reference
 *	@sb: reference we are trying to grab
 *
 *	Tries to acquire a passive reference. This is used in places where we
 *	cannot take an active reference but we need to ensure that the
 *	superblock does not go away while we are working on it. It returns
 *	false if a reference was not gained, and returns true with the s_umount
 *	lock held in read mode if a reference is gained. On successful return,
 *	the caller must drop the s_umount lock and the passive reference when
 *	done.
 */
bool grab_super_passive(struct super_block *sb)
{
	spin_lock(&sb_lock);
	if (hlist_unhashed(&sb->s_instances)) {
		spin_unlock(&sb_lock);
		return false;
	}

	sb->s_count++;
	spin_unlock(&sb_lock);

	if (down_read_trylock(&sb->s_umount)) {
		if (sb->s_root && (sb->s_flags & MS_BORN))
			return true;
		up_read(&sb->s_umount);
	}