edac_mc.c

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/*
 * edac_mc kernel module
 * (C) 2005, 2006 Linux Networx (http://lnxi.com)
 * This file may be distributed under the terms of the
 * GNU General Public License.
 *
 * Written by Thayne Harbaugh
 * Based on work by Dan Hollis <goemon at anime dot net> and others.
 *	http://www.anime.net/~goemon/linux-ecc/
 *
 * Modified by Dave Peterson and Doug Thompson
 *
 */

#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sysdev.h>
#include <linux/ctype.h>
#include <linux/edac.h>
#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/edac.h>
#include "edac_core.h"
#include "edac_module.h"

/* lock to memory controller's control array */
static DEFINE_MUTEX(mem_ctls_mutex);
static struct list_head mc_devices = LIST_HEAD_INIT(mc_devices);

#ifdef CONFIG_EDAC_DEBUG

static void edac_mc_dump_channel(struct channel_info *chan)
{
	debugf4("\tchannel = %p\n", chan);
	debugf4("\tchannel->chan_idx = %d\n", chan->chan_idx);
	debugf4("\tchannel->ce_count = %d\n", chan->ce_count);
	debugf4("\tchannel->label = '%s'\n", chan->label);
	debugf4("\tchannel->csrow = %p\n\n", chan->csrow);
}

static void edac_mc_dump_csrow(struct csrow_info *csrow)
{
	debugf4("\tcsrow = %p\n", csrow);
	debugf4("\tcsrow->csrow_idx = %d\n", csrow->csrow_idx);
	debugf4("\tcsrow->first_page = 0x%lx\n", csrow->first_page);
	debugf4("\tcsrow->last_page = 0x%lx\n", csrow->last_page);
	debugf4("\tcsrow->page_mask = 0x%lx\n", csrow->page_mask);
	debugf4("\tcsrow->nr_pages = 0x%x\n", csrow->nr_pages);
	debugf4("\tcsrow->nr_channels = %d\n", csrow->nr_channels);
	debugf4("\tcsrow->channels = %p\n", csrow->channels);
	debugf4("\tcsrow->mci = %p\n\n", csrow->mci);
}

static void edac_mc_dump_mci(struct mem_ctl_info *mci)
{
	debugf3("\tmci = %p\n", mci);
	debugf3("\tmci->mtype_cap = %lx\n", mci->mtype_cap);
	debugf3("\tmci->edac_ctl_cap = %lx\n", mci->edac_ctl_cap);
	debugf3("\tmci->edac_cap = %lx\n", mci->edac_cap);
	debugf4("\tmci->edac_check = %p\n", mci->edac_check);
	debugf3("\tmci->nr_csrows = %d, csrows = %p\n",
		mci->nr_csrows, mci->csrows);
	debugf3("\tdev = %p\n", mci->dev);
	debugf3("\tmod_name:ctl_name = %s:%s\n", mci->mod_name, mci->ctl_name);
	debugf3("\tpvt_info = %p\n\n", mci->pvt_info);
}

#endif				/* CONFIG_EDAC_DEBUG */

/* 'ptr' points to a possibly unaligned item X such that sizeof(X) is 'size'.
 * Adjust 'ptr' so that its alignment is at least as stringent as what the
 * compiler would provide for X and return the aligned result.
 *
 * If 'size' is a constant, the compiler will optimize this whole function
 * down to either a no-op or the addition of a constant to the value of 'ptr'.
 */
void *edac_align_ptr(void *ptr, unsigned size)
{
	unsigned align, r;

	/* Here we assume that the alignment of a "long long" is the most
	 * stringent alignment that the compiler will ever provide by default.
	 * As far as I know, this is a reasonable assumption.
	 */
	if (size > sizeof(long))
		align = sizeof(long long);
	else if (size > sizeof(int))
		align = sizeof(long);
	else if (size > sizeof(short))
		align = sizeof(int);
	else if (size > sizeof(char))
		align = sizeof(short);
	else
		return (char *)ptr;

	r = size % align;

	if (r == 0)
		return (char *)ptr;

	return (void *)(((unsigned long)ptr) + align - r);
}

/**
 * edac_mc_alloc: Allocate a struct mem_ctl_info structure
 * @size_pvt:	size of private storage needed
 * @nr_csrows:	Number of CWROWS needed for this MC
 * @nr_chans:	Number of channels for the MC
 *
 * Everything is kmalloc'ed as one big chunk - more efficient.
 * Only can be used if all structures have the same lifetime - otherwise
 * you have to allocate and initialize your own structures.
 *
 * Use edac_mc_free() to free mc structures allocated by this function.
 *
 * Returns:
 *	NULL allocation failed
 *	struct mem_ctl_info pointer
 */
struct mem_ctl_info *edac_mc_alloc(unsigned sz_pvt, unsigned nr_csrows,
				unsigned nr_chans, int edac_index)
{
	struct mem_ctl_info *mci;
	struct csrow_info *csi, *csrow;
	struct channel_info *chi, *chp, *chan;
	void *pvt;
	unsigned size;
	int row, chn;
	int err;

	/* Figure out the offsets of the various items from the start of an mc
	 * structure.  We want the alignment of each item to be at least as
	 * stringent as what the compiler would provide if we could simply
	 * hardcode everything into a single struct.
	 */
	mci = (struct mem_ctl_info *)0;
	csi = edac_align_ptr(&mci[1], sizeof(*csi));
	chi = edac_align_ptr(&csi[nr_csrows], sizeof(*chi));
	pvt = edac_align_ptr(&chi[nr_chans * nr_csrows], sz_pvt);
	size = ((unsigned long)pvt) + sz_pvt;

	mci = kzalloc(size, GFP_KERNEL);
	if (mci == NULL)
		return NULL;

	/* Adjust pointers so they point within the memory we just allocated
	 * rather than an imaginary chunk of memory located at address 0.
	 */
	csi = (struct csrow_info *)(((char *)mci) + ((unsigned long)csi));
	chi = (struct channel_info *)(((char *)mci) + ((unsigned long)chi));
	pvt = sz_pvt ? (((char *)mci) + ((unsigned long)pvt)) : NULL;

	/* setup index and various internal pointers */
	mci->mc_idx = edac_index;
	mci->csrows = csi;
	mci->pvt_info = pvt;
	mci->nr_csrows = nr_csrows;

	for (row = 0; row < nr_csrows; row++) {
		csrow = &csi[row];
		csrow->csrow_idx = row;
		csrow->mci = mci;
		csrow->nr_channels = nr_chans;
		chp = &chi[row * nr_chans];
		csrow->channels = chp;

		for (chn = 0; chn < nr_chans; chn++) {
			chan = &chp[chn];
			chan->chan_idx = chn;
			chan->csrow = csrow;
		}
	}

	mci->op_state = OP_ALLOC;

	/*
	 * Initialize the 'root' kobj for the edac_mc controller
	 */
	err = edac_mc_register_sysfs_main_kobj(mci);
	if (err) {
		kfree(mci);
		return NULL;
	}

	/* at this point, the root kobj is valid, and in order to
	 * 'free' the object, then the function:
	 *      edac_mc_unregister_sysfs_main_kobj() must be called
	 * which will perform kobj unregistration and the actual free
	 * will occur during the kobject callback operation
	 */
	return mci;
}
EXPORT_SYMBOL_GPL(edac_mc_alloc);

/**
 * edac_mc_free
 *	'Free' a previously allocated 'mci' structure
 * @mci: pointer to a struct mem_ctl_info structure
 */
void edac_mc_free(struct mem_ctl_info *mci)
{
	edac_mc_unregister_sysfs_main_kobj(mci);
}
EXPORT_SYMBOL_GPL(edac_mc_free);


/*
 * find_mci_by_dev
 *
 *	scan list of controllers looking for the one that manages
 *	the 'dev' device
 */
static struct mem_ctl_info *find_mci_by_dev(struct device *dev)
{
	struct mem_ctl_info *mci;
	struct list_head *item;

	debugf3("%s()\n", __func__);

	list_for_each(item, &mc_devices) {
		mci = list_entry(item, struct mem_ctl_info, link);

		if (mci->dev == dev)
			return mci;
	}

	return NULL;
}

/*
 * handler for EDAC to check if NMI type handler has asserted interrupt
 */
static int edac_mc_assert_error_check_and_clear(void)
{
	int old_state;

	if (edac_op_state == EDAC_OPSTATE_POLL)
		return 1;

	old_state = edac_err_assert;
	edac_err_assert = 0;

	return old_state;
}

/*
 * edac_mc_workq_function
 *	performs the operation scheduled by a workq request
 */
static void edac_mc_workq_function(struct work_struct *work_req)
{
	struct delayed_work *d_work = (struct delayed_work *)work_req;
	struct mem_ctl_info *mci = to_edac_mem_ctl_work(d_work);

	mutex_lock(&mem_ctls_mutex);

	/* if this control struct has movd to offline state, we are done */
	if (mci->op_state == OP_OFFLINE) {
		mutex_unlock(&mem_ctls_mutex);
		return;
	}

	/* Only poll controllers that are running polled and have a check */
	if (edac_mc_assert_error_check_and_clear() && (mci->edac_check != NULL))
		mci->edac_check(mci);

	mutex_unlock(&mem_ctls_mutex);

	/* Reschedule */
	queue_delayed_work(edac_workqueue, &mci->work,
			msecs_to_jiffies(edac_mc_get_poll_msec()));
}

/*
 * edac_mc_workq_setup
 *	initialize a workq item for this mci
 *	passing in the new delay period in msec
 *
 *	locking model:
 *
 *		called with the mem_ctls_mutex held
 */
static void edac_mc_workq_setup(struct mem_ctl_info *mci, unsigned msec)
{
	debugf0("%s()\n", __func__);

	/* if this instance is not in the POLL state, then simply return */
	if (mci->op_state != OP_RUNNING_POLL)
		return;

	INIT_DELAYED_WORK(&mci->work, edac_mc_workq_function);
	queue_delayed_work(edac_workqueue, &mci->work, msecs_to_jiffies(msec));
}

/*
 * edac_mc_workq_teardown
 *	stop the workq processing on this mci
 *
 *	locking model:
 *
 *		called WITHOUT lock held
 */
static void edac_mc_workq_teardown(struct mem_ctl_info *mci)
{
	int status;

	status = cancel_delayed_work(&mci->work);
	if (status == 0) {
		debugf0("%s() not canceled, flush the queue\n",
			__func__);

		/* workq instance might be running, wait for it */
		flush_workqueue(edac_workqueue);
	}
}

/*
 * edac_mc_reset_delay_period(unsigned long value)
 *
 *	user space has updated our poll period value, need to
 *	reset our workq delays
 */
void edac_mc_reset_delay_period(int value)
{
	struct mem_ctl_info *mci;
	struct list_head *item;

	mutex_lock(&mem_ctls_mutex);

	/* scan the list and turn off all workq timers, doing so under lock
	 */
	list_for_each(item, &mc_devices) {
		mci = list_entry(item, struct mem_ctl_info, link);

		if (mci->op_state == OP_RUNNING_POLL)
			cancel_delayed_work(&mci->work);
	}

	mutex_unlock(&mem_ctls_mutex);


	/* re-walk the list, and reset the poll delay */
	mutex_lock(&mem_ctls_mutex);

	list_for_each(item, &mc_devices) {
		mci = list_entry(item, struct mem_ctl_info, link);

		edac_mc_workq_setup(mci, (unsigned long) value);
	}

	mutex_unlock(&mem_ctls_mutex);
}



/* Return 0 on success, 1 on failure.
 * Before calling this function, caller must
 * assign a unique value to mci->mc_idx.
 *
 *	locking model:
 *
 *		called with the mem_ctls_mutex lock held
 */
static int add_mc_to_global_list(struct mem_ctl_info *mci)
{
	struct list_head *item, *insert_before;
	struct mem_ctl_info *p;

	insert_before = &mc_devices;

	p = find_mci_by_dev(mci->dev);
	if (unlikely(p != NULL))
		goto fail0;

	list_for_each(item, &mc_devices) {
		p = list_entry(item, struct mem_ctl_info, link);

		if (p->mc_idx >= mci->mc_idx) {
			if (unlikely(p->mc_idx == mci->mc_idx))
				goto fail1;

			insert_before = item;
			break;
		}
	}

	list_add_tail_rcu(&mci->link, insert_before);
	atomic_inc(&edac_handlers);
	return 0;

fail0:
	edac_printk(KERN_WARNING, EDAC_MC,
		"%s (%s) %s %s already assigned %d\n", p->dev->bus_id,
		dev_name(mci), p->mod_name, p->ctl_name, p->mc_idx);
	return 1;

fail1:
	edac_printk(KERN_WARNING, EDAC_MC,
		"bug in low-level driver: attempt to assign\n"
		"    duplicate mc_idx %d in %s()\n", p->mc_idx, __func__);
	return 1;
}

static void complete_mc_list_del(struct rcu_head *head)
{
	struct mem_ctl_info *mci;

	mci = container_of(head, struct mem_ctl_info, rcu);
	INIT_LIST_HEAD(&mci->link);
	complete(&mci->complete);
}

static void del_mc_from_global_list(struct mem_ctl_info *mci)
{
	atomic_dec(&edac_handlers);
	list_del_rcu(&mci->link);
	init_completion(&mci->complete);
	call_rcu(&mci->rcu, complete_mc_list_del);
	wait_for_completion(&mci->complete);
}

/**
 * edac_mc_find: Search for a mem_ctl_info structure whose index is 'idx'.
 *
 * If found, return a pointer to the structure.
 * Else return NULL.
 *
 * Caller must hold mem_ctls_mutex.
 */
struct mem_ctl_info *edac_mc_find(int idx)
{
	struct list_head *item;
	struct mem_ctl_info *mci;

	list_for_each(item, &mc_devices) {
		mci = list_entry(item, struct mem_ctl_info, link);

		if (mci->mc_idx >= idx) {
			if (mci->mc_idx == idx)
				return mci;

			break;
		}
	}