Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

[cris-mirror.git] / drivers / edac / edac_mc.c

/*
 * 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/ctype.h>
#include <linux/edac.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include "edac_mc.h"
#include "edac_module.h"
#include <ras/ras_event.h>

#ifdef CONFIG_EDAC_ATOMIC_SCRUB
#include <asm/edac.h>
#else
#define edac_atomic_scrub(va, size) do { } while (0)
#endif

int edac_op_state = EDAC_OPSTATE_INVAL;
EXPORT_SYMBOL_GPL(edac_op_state);

static int edac_report = EDAC_REPORTING_ENABLED;

/* lock to memory controller's control array */
static DEFINE_MUTEX(mem_ctls_mutex);
static LIST_HEAD(mc_devices);

/*
 * Used to lock EDAC MC to just one module, avoiding two drivers e. g.
 *      apei/ghes and i7core_edac to be used at the same time.
 */
static const char *edac_mc_owner;

static struct bus_type mc_bus[EDAC_MAX_MCS];

int edac_get_report_status(void)
{
        return edac_report;
}
EXPORT_SYMBOL_GPL(edac_get_report_status);

void edac_set_report_status(int new)
{
        if (new == EDAC_REPORTING_ENABLED ||
            new == EDAC_REPORTING_DISABLED ||
            new == EDAC_REPORTING_FORCE)
                edac_report = new;
}
EXPORT_SYMBOL_GPL(edac_set_report_status);

static int edac_report_set(const char *str, const struct kernel_param *kp)
{
        if (!str)
                return -EINVAL;

        if (!strncmp(str, "on", 2))
                edac_report = EDAC_REPORTING_ENABLED;
        else if (!strncmp(str, "off", 3))
                edac_report = EDAC_REPORTING_DISABLED;
        else if (!strncmp(str, "force", 5))
                edac_report = EDAC_REPORTING_FORCE;

        return 0;
}

static int edac_report_get(char *buffer, const struct kernel_param *kp)
{
        int ret = 0;

        switch (edac_report) {
        case EDAC_REPORTING_ENABLED:
                ret = sprintf(buffer, "on");
                break;
        case EDAC_REPORTING_DISABLED:
                ret = sprintf(buffer, "off");
                break;
        case EDAC_REPORTING_FORCE:
                ret = sprintf(buffer, "force");
                break;
        default:
                ret = -EINVAL;
                break;
        }

        return ret;
}

static const struct kernel_param_ops edac_report_ops = {
        .set = edac_report_set,
        .get = edac_report_get,
};

module_param_cb(edac_report, &edac_report_ops, &edac_report, 0644);

unsigned edac_dimm_info_location(struct dimm_info *dimm, char *buf,
                                 unsigned len)
{
        struct mem_ctl_info *mci = dimm->mci;
        int i, n, count = 0;
        char *p = buf;

        for (i = 0; i < mci->n_layers; i++) {
                n = snprintf(p, len, "%s %d ",
                              edac_layer_name[mci->layers[i].type],
                              dimm->location[i]);
                p += n;
                len -= n;
                count += n;
                if (!len)
                        break;
        }

        return count;
}

#ifdef CONFIG_EDAC_DEBUG

static void edac_mc_dump_channel(struct rank_info *chan)
{
        edac_dbg(4, "  channel->chan_idx = %d\n", chan->chan_idx);
        edac_dbg(4, "    channel = %p\n", chan);
        edac_dbg(4, "    channel->csrow = %p\n", chan->csrow);
        edac_dbg(4, "    channel->dimm = %p\n", chan->dimm);
}

static void edac_mc_dump_dimm(struct dimm_info *dimm, int number)
{
        char location[80];

        edac_dimm_info_location(dimm, location, sizeof(location));

        edac_dbg(4, "%s%i: %smapped as virtual row %d, chan %d\n",
                 dimm->mci->csbased ? "rank" : "dimm",
                 number, location, dimm->csrow, dimm->cschannel);
        edac_dbg(4, "  dimm = %p\n", dimm);
        edac_dbg(4, "  dimm->label = '%s'\n", dimm->label);
        edac_dbg(4, "  dimm->nr_pages = 0x%x\n", dimm->nr_pages);
        edac_dbg(4, "  dimm->grain = %d\n", dimm->grain);
        edac_dbg(4, "  dimm->nr_pages = 0x%x\n", dimm->nr_pages);
}

static void edac_mc_dump_csrow(struct csrow_info *csrow)
{
        edac_dbg(4, "csrow->csrow_idx = %d\n", csrow->csrow_idx);
        edac_dbg(4, "  csrow = %p\n", csrow);
        edac_dbg(4, "  csrow->first_page = 0x%lx\n", csrow->first_page);
        edac_dbg(4, "  csrow->last_page = 0x%lx\n", csrow->last_page);
        edac_dbg(4, "  csrow->page_mask = 0x%lx\n", csrow->page_mask);
        edac_dbg(4, "  csrow->nr_channels = %d\n", csrow->nr_channels);
        edac_dbg(4, "  csrow->channels = %p\n", csrow->channels);
        edac_dbg(4, "  csrow->mci = %p\n", csrow->mci);
}

static void edac_mc_dump_mci(struct mem_ctl_info *mci)
{
        edac_dbg(3, "\tmci = %p\n", mci);
        edac_dbg(3, "\tmci->mtype_cap = %lx\n", mci->mtype_cap);
        edac_dbg(3, "\tmci->edac_ctl_cap = %lx\n", mci->edac_ctl_cap);
        edac_dbg(3, "\tmci->edac_cap = %lx\n", mci->edac_cap);
        edac_dbg(4, "\tmci->edac_check = %p\n", mci->edac_check);
        edac_dbg(3, "\tmci->nr_csrows = %d, csrows = %p\n",
                 mci->nr_csrows, mci->csrows);
        edac_dbg(3, "\tmci->nr_dimms = %d, dimms = %p\n",
                 mci->tot_dimms, mci->dimms);
        edac_dbg(3, "\tdev = %p\n", mci->pdev);
        edac_dbg(3, "\tmod_name:ctl_name = %s:%s\n",
                 mci->mod_name, mci->ctl_name);
        edac_dbg(3, "\tpvt_info = %p\n\n", mci->pvt_info);
}

#endif                          /* CONFIG_EDAC_DEBUG */

const char * const edac_mem_types[] = {
        [MEM_EMPTY]     = "Empty csrow",
        [MEM_RESERVED]  = "Reserved csrow type",
        [MEM_UNKNOWN]   = "Unknown csrow type",
        [MEM_FPM]       = "Fast page mode RAM",
        [MEM_EDO]       = "Extended data out RAM",
        [MEM_BEDO]      = "Burst Extended data out RAM",
        [MEM_SDR]       = "Single data rate SDRAM",
        [MEM_RDR]       = "Registered single data rate SDRAM",
        [MEM_DDR]       = "Double data rate SDRAM",
        [MEM_RDDR]      = "Registered Double data rate SDRAM",
        [MEM_RMBS]      = "Rambus DRAM",
        [MEM_DDR2]      = "Unbuffered DDR2 RAM",
        [MEM_FB_DDR2]   = "Fully buffered DDR2",
        [MEM_RDDR2]     = "Registered DDR2 RAM",
        [MEM_XDR]       = "Rambus XDR",
        [MEM_DDR3]      = "Unbuffered DDR3 RAM",
        [MEM_RDDR3]     = "Registered DDR3 RAM",
        [MEM_LRDDR3]    = "Load-Reduced DDR3 RAM",
        [MEM_DDR4]      = "Unbuffered DDR4 RAM",
        [MEM_RDDR4]     = "Registered DDR4 RAM",
};
EXPORT_SYMBOL_GPL(edac_mem_types);

/**
 * edac_align_ptr - Prepares the pointer offsets for a single-shot allocation
 * @p:          pointer to a pointer with the memory offset to be used. At
 *              return, this will be incremented to point to the next offset
 * @size:       Size of the data structure to be reserved
 * @n_elems:    Number of elements that should be reserved
 *
 * 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 '*p'.
 *
 * The 'p' pointer is absolutely needed to keep the proper advancing
 * further in memory to the proper offsets when allocating the struct along
 * with its embedded structs, as edac_device_alloc_ctl_info() does it
 * above, for example.
 *
 * At return, the pointer 'p' will be incremented to be used on a next call
 * to this function.
 */
void *edac_align_ptr(void **p, unsigned size, int n_elems)
{
        unsigned align, r;
        void *ptr = *p;

        *p += size * n_elems;

        /*
         * 'p' can possibly be an unaligned item X such that sizeof(X) is
         * 'size'.  Adjust 'p' so that its alignment is at least as
         * stringent as what the compiler would provide for X and return
         * the aligned result.
         * 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 = (unsigned long)p % align;

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

        *p += align - r;

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

static void _edac_mc_free(struct mem_ctl_info *mci)
{
        int i, chn, row;
        struct csrow_info *csr;
        const unsigned int tot_dimms = mci->tot_dimms;
        const unsigned int tot_channels = mci->num_cschannel;
        const unsigned int tot_csrows = mci->nr_csrows;

        if (mci->dimms) {
                for (i = 0; i < tot_dimms; i++)
                        kfree(mci->dimms[i]);
                kfree(mci->dimms);
        }
        if (mci->csrows) {
                for (row = 0; row < tot_csrows; row++) {
                        csr = mci->csrows[row];
                        if (csr) {
                                if (csr->channels) {
                                        for (chn = 0; chn < tot_channels; chn++)
                                                kfree(csr->channels[chn]);
                                        kfree(csr->channels);
                                }
                                kfree(csr);
                        }
                }
                kfree(mci->csrows);
        }
        kfree(mci);
}

struct mem_ctl_info *edac_mc_alloc(unsigned mc_num,
                                   unsigned n_layers,
                                   struct edac_mc_layer *layers,
                                   unsigned sz_pvt)
{
        struct mem_ctl_info *mci;
        struct edac_mc_layer *layer;
        struct csrow_info *csr;
        struct rank_info *chan;
        struct dimm_info *dimm;
        u32 *ce_per_layer[EDAC_MAX_LAYERS], *ue_per_layer[EDAC_MAX_LAYERS];
        unsigned pos[EDAC_MAX_LAYERS];
        unsigned size, tot_dimms = 1, count = 1;
        unsigned tot_csrows = 1, tot_channels = 1, tot_errcount = 0;
        void *pvt, *p, *ptr = NULL;
        int i, j, row, chn, n, len, off;
        bool per_rank = false;

        BUG_ON(n_layers > EDAC_MAX_LAYERS || n_layers == 0);
        /*
         * Calculate the total amount of dimms and csrows/cschannels while
         * in the old API emulation mode
         */
        for (i = 0; i < n_layers; i++) {
                tot_dimms *= layers[i].size;
                if (layers[i].is_virt_csrow)
                        tot_csrows *= layers[i].size;
                else
                        tot_channels *= layers[i].size;

                if (layers[i].type == EDAC_MC_LAYER_CHIP_SELECT)
                        per_rank = true;
        }

        /* 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 = edac_align_ptr(&ptr, sizeof(*mci), 1);
        layer = edac_align_ptr(&ptr, sizeof(*layer), n_layers);
        for (i = 0; i < n_layers; i++) {
                count *= layers[i].size;
                edac_dbg(4, "errcount layer %d size %d\n", i, count);
                ce_per_layer[i] = edac_align_ptr(&ptr, sizeof(u32), count);
                ue_per_layer[i] = edac_align_ptr(&ptr, sizeof(u32), count);
                tot_errcount += 2 * count;
        }

        edac_dbg(4, "allocating %d error counters\n", tot_errcount);
        pvt = edac_align_ptr(&ptr, sz_pvt, 1);
        size = ((unsigned long)pvt) + sz_pvt;

        edac_dbg(1, "allocating %u bytes for mci data (%d %s, %d csrows/channels)\n",
                 size,
                 tot_dimms,
                 per_rank ? "ranks" : "dimms",
                 tot_csrows * tot_channels);

        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.
         */
        layer = (struct edac_mc_layer *)(((char *)mci) + ((unsigned long)layer));
        for (i = 0; i < n_layers; i++) {
                mci->ce_per_layer[i] = (u32 *)((char *)mci + ((unsigned long)ce_per_layer[i]));
                mci->ue_per_layer[i] = (u32 *)((char *)mci + ((unsigned long)ue_per_layer[i]));
        }
        pvt = sz_pvt ? (((char *)mci) + ((unsigned long)pvt)) : NULL;

        /* setup index and various internal pointers */
        mci->mc_idx = mc_num;
        mci->tot_dimms = tot_dimms;
        mci->pvt_info = pvt;
        mci->n_layers = n_layers;
        mci->layers = layer;
        memcpy(mci->layers, layers, sizeof(*layer) * n_layers);
        mci->nr_csrows = tot_csrows;
        mci->num_cschannel = tot_channels;
        mci->csbased = per_rank;

        /*
         * Alocate and fill the csrow/channels structs
         */
        mci->csrows = kcalloc(tot_csrows, sizeof(*mci->csrows), GFP_KERNEL);
        if (!mci->csrows)
                goto error;
        for (row = 0; row < tot_csrows; row++) {
                csr = kzalloc(sizeof(**mci->csrows), GFP_KERNEL);
                if (!csr)
                        goto error;
                mci->csrows[row] = csr;
                csr->csrow_idx = row;
                csr->mci = mci;
                csr->nr_channels = tot_channels;
                csr->channels = kcalloc(tot_channels, sizeof(*csr->channels),
                                        GFP_KERNEL);
                if (!csr->channels)
                        goto error;

                for (chn = 0; chn < tot_channels; chn++) {
                        chan = kzalloc(sizeof(**csr->channels), GFP_KERNEL);
                        if (!chan)
                                goto error;
                        csr->channels[chn] = chan;
                        chan->chan_idx = chn;
                        chan->csrow = csr;
                }
        }

        /*
         * Allocate and fill the dimm structs
         */
        mci->dimms  = kcalloc(tot_dimms, sizeof(*mci->dimms), GFP_KERNEL);
        if (!mci->dimms)
                goto error;

        memset(&pos, 0, sizeof(pos));
        row = 0;
        chn = 0;
        for (i = 0; i < tot_dimms; i++) {
                chan = mci->csrows[row]->channels[chn];
                off = EDAC_DIMM_OFF(layer, n_layers, pos[0], pos[1], pos[2]);
                if (off < 0 || off >= tot_dimms) {
                        edac_mc_printk(mci, KERN_ERR, "EDAC core bug: EDAC_DIMM_OFF is trying to do an illegal data access\n");
                        goto error;
                }

                dimm = kzalloc(sizeof(**mci->dimms), GFP_KERNEL);
                if (!dimm)
                        goto error;
                mci->dimms[off] = dimm;
                dimm->mci = mci;

                /*
                 * Copy DIMM location and initialize it.
                 */
                len = sizeof(dimm->label);
                p = dimm->label;
                n = snprintf(p, len, "mc#%u", mc_num);
                p += n;
                len -= n;
                for (j = 0; j < n_layers; j++) {
                        n = snprintf(p, len, "%s#%u",
                                     edac_layer_name[layers[j].type],
                                     pos[j]);
                        p += n;
                        len -= n;
                        dimm->location[j] = pos[j];

                        if (len <= 0)
                                break;
                }

                /* Link it to the csrows old API data */
                chan->dimm = dimm;
                dimm->csrow = row;
                dimm->cschannel = chn;

                /* Increment csrow location */
                if (layers[0].is_virt_csrow) {
                        chn++;
                        if (chn == tot_channels) {
                                chn = 0;
                                row++;
                        }
                } else {
                        row++;
                        if (row == tot_csrows) {
                                row = 0;
                                chn++;
                        }
                }

                /* Increment dimm location */
                for (j = n_layers - 1; j >= 0; j--) {
                        pos[j]++;
                        if (pos[j] < layers[j].size)
                                break;
                        pos[j] = 0;
                }
        }

        mci->op_state = OP_ALLOC;

        return mci;

error:
        _edac_mc_free(mci);

        return NULL;
}
EXPORT_SYMBOL_GPL(edac_mc_alloc);

void edac_mc_free(struct mem_ctl_info *mci)
{
        edac_dbg(1, "\n");

        /* If we're not yet registered with sysfs free only what was allocated
         * in edac_mc_alloc().
         */
        if (!device_is_registered(&mci->dev)) {
                _edac_mc_free(mci);
                return;
        }

        /* the mci instance is freed here, when the sysfs object is dropped */
        edac_unregister_sysfs(mci);
}
EXPORT_SYMBOL_GPL(edac_mc_free);

bool edac_has_mcs(void)
{
        bool ret;

        mutex_lock(&mem_ctls_mutex);

        ret = list_empty(&mc_devices);

        mutex_unlock(&mem_ctls_mutex);

        return !ret;
}
EXPORT_SYMBOL_GPL(edac_has_mcs);

/* Caller must hold mem_ctls_mutex */
static struct mem_ctl_info *__find_mci_by_dev(struct device *dev)
{
        struct mem_ctl_info *mci;
        struct list_head *item;

        edac_dbg(3, "\n");

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

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

        return NULL;
}

/**
 * find_mci_by_dev
 *
 *      scan list of controllers looking for the one that manages
 *      the 'dev' device
 * @dev: pointer to a struct device related with the MCI
 */
struct mem_ctl_info *find_mci_by_dev(struct device *dev)
{
        struct mem_ctl_info *ret;

        mutex_lock(&mem_ctls_mutex);
        ret = __find_mci_by_dev(dev);
        mutex_unlock(&mem_ctls_mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(find_mci_by_dev);

/*
 * 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 = to_delayed_work(work_req);
        struct mem_ctl_info *mci = to_edac_mem_ctl_work(d_work);

        mutex_lock(&mem_ctls_mutex);

        if (mci->op_state != OP_RUNNING_POLL) {
                mutex_unlock(&mem_ctls_mutex);
                return;
        }

        if (edac_op_state == EDAC_OPSTATE_POLL)
                mci->edac_check(mci);

        mutex_unlock(&mem_ctls_mutex);

        /* Queue ourselves again. */
        edac_queue_work(&mci->work, msecs_to_jiffies(edac_mc_get_poll_msec()));
}

/*
 * 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(unsigned long value)
{
        struct mem_ctl_info *mci;
        struct list_head *item;

        mutex_lock(&mem_ctls_mutex);

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

                if (mci->op_state == OP_RUNNING_POLL)
                        edac_mod_work(&mci->work, 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->pdev);
        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);
        return 0;

fail0:
        edac_printk(KERN_WARNING, EDAC_MC,
                "%s (%s) %s %s already assigned %d\n", dev_name(p->pdev),
                edac_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 int del_mc_from_global_list(struct mem_ctl_info *mci)
{
        list_del_rcu(&mci->link);

        /* these are for safe removal of devices from global list while
         * NMI handlers may be traversing list
         */
        synchronize_rcu();
        INIT_LIST_HEAD(&mci->link);

        return list_empty(&mc_devices);
}

struct mem_ctl_info *edac_mc_find(int idx)
{
        struct mem_ctl_info *mci = NULL;
        struct list_head *item;

        mutex_lock(&mem_ctls_mutex);

        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) {
                                goto unlock;
                        }
                        break;
                }
        }

unlock:
        mutex_unlock(&mem_ctls_mutex);
        return mci;
}
EXPORT_SYMBOL(edac_mc_find);

const char *edac_get_owner(void)
{
        return edac_mc_owner;
}
EXPORT_SYMBOL_GPL(edac_get_owner);

/* FIXME - should a warning be printed if no error detection? correction? */
int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,
                               const struct attribute_group **groups)
{
        int ret = -EINVAL;
        edac_dbg(0, "\n");

        if (mci->mc_idx >= EDAC_MAX_MCS) {
                pr_warn_once("Too many memory controllers: %d\n", mci->mc_idx);
                return -ENODEV;
        }

#ifdef CONFIG_EDAC_DEBUG
        if (edac_debug_level >= 3)
                edac_mc_dump_mci(mci);

        if (edac_debug_level >= 4) {
                int i;

                for (i = 0; i < mci->nr_csrows; i++) {
                        struct csrow_info *csrow = mci->csrows[i];
                        u32 nr_pages = 0;
                        int j;

                        for (j = 0; j < csrow->nr_channels; j++)
                                nr_pages += csrow->channels[j]->dimm->nr_pages;
                        if (!nr_pages)
                                continue;
                        edac_mc_dump_csrow(csrow);
                        for (j = 0; j < csrow->nr_channels; j++)
                                if (csrow->channels[j]->dimm->nr_pages)
                                        edac_mc_dump_channel(csrow->channels[j]);
                }
                for (i = 0; i < mci->tot_dimms; i++)
                        if (mci->dimms[i]->nr_pages)
                                edac_mc_dump_dimm(mci->dimms[i], i);
        }
#endif
        mutex_lock(&mem_ctls_mutex);

        if (edac_mc_owner && edac_mc_owner != mci->mod_name) {
                ret = -EPERM;
                goto fail0;
        }

        if (add_mc_to_global_list(mci))
                goto fail0;

        /* set load time so that error rate can be tracked */
        mci->start_time = jiffies;

        mci->bus = &mc_bus[mci->mc_idx];

        if (edac_create_sysfs_mci_device(mci, groups)) {
                edac_mc_printk(mci, KERN_WARNING,
                        "failed to create sysfs device\n");
                goto fail1;
        }

        if (mci->edac_check) {
                mci->op_state = OP_RUNNING_POLL;

                INIT_DELAYED_WORK(&mci->work, edac_mc_workq_function);
                edac_queue_work(&mci->work, msecs_to_jiffies(edac_mc_get_poll_msec()));

        } else {
                mci->op_state = OP_RUNNING_INTERRUPT;
        }

        /* Report action taken */
        edac_mc_printk(mci, KERN_INFO,
                "Giving out device to module %s controller %s: DEV %s (%s)\n",
                mci->mod_name, mci->ctl_name, mci->dev_name,
                edac_op_state_to_string(mci->op_state));

        edac_mc_owner = mci->mod_name;

        mutex_unlock(&mem_ctls_mutex);
        return 0;

fail1:
        del_mc_from_global_list(mci);

fail0:
        mutex_unlock(&mem_ctls_mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(edac_mc_add_mc_with_groups);

struct mem_ctl_info *edac_mc_del_mc(struct device *dev)
{
        struct mem_ctl_info *mci;

        edac_dbg(0, "\n");

        mutex_lock(&mem_ctls_mutex);

        /* find the requested mci struct in the global list */
        mci = __find_mci_by_dev(dev);
        if (mci == NULL) {
                mutex_unlock(&mem_ctls_mutex);
                return NULL;
        }

        /* mark MCI offline: */
        mci->op_state = OP_OFFLINE;

        if (del_mc_from_global_list(mci))
                edac_mc_owner = NULL;

        mutex_unlock(&mem_ctls_mutex);

        if (mci->edac_check)
                edac_stop_work(&mci->work);

        /* remove from sysfs */
        edac_remove_sysfs_mci_device(mci);

        edac_printk(KERN_INFO, EDAC_MC,
                "Removed device %d for %s %s: DEV %s\n", mci->mc_idx,
                mci->mod_name, mci->ctl_name, edac_dev_name(mci));

        return mci;
}
EXPORT_SYMBOL_GPL(edac_mc_del_mc);

static void edac_mc_scrub_block(unsigned long page, unsigned long offset,
                                u32 size)
{
        struct page *pg;
        void *virt_addr;
        unsigned long flags = 0;

        edac_dbg(3, "\n");

        /* ECC error page was not in our memory. Ignore it. */
        if (!pfn_valid(page))
                return;

        /* Find the actual page structure then map it and fix */
        pg = pfn_to_page(page);

        if (PageHighMem(pg))
                local_irq_save(flags);

        virt_addr = kmap_atomic(pg);

        /* Perform architecture specific atomic scrub operation */
        edac_atomic_scrub(virt_addr + offset, size);

        /* Unmap and complete */
        kunmap_atomic(virt_addr);

        if (PageHighMem(pg))
                local_irq_restore(flags);
}

/* FIXME - should return -1 */
int edac_mc_find_csrow_by_page(struct mem_ctl_info *mci, unsigned long page)
{
        struct csrow_info **csrows = mci->csrows;
        int row, i, j, n;

        edac_dbg(1, "MC%d: 0x%lx\n", mci->mc_idx, page);
        row = -1;

        for (i = 0; i < mci->nr_csrows; i++) {
                struct csrow_info *csrow = csrows[i];
                n = 0;
                for (j = 0; j < csrow->nr_channels; j++) {
                        struct dimm_info *dimm = csrow->channels[j]->dimm;
                        n += dimm->nr_pages;
                }
                if (n == 0)
                        continue;

                edac_dbg(3, "MC%d: first(0x%lx) page(0x%lx) last(0x%lx) mask(0x%lx)\n",
                         mci->mc_idx,
                         csrow->first_page, page, csrow->last_page,
                         csrow->page_mask);

                if ((page >= csrow->first_page) &&
                    (page <= csrow->last_page) &&
                    ((page & csrow->page_mask) ==
                     (csrow->first_page & csrow->page_mask))) {
                        row = i;
                        break;
                }
        }

        if (row == -1)
                edac_mc_printk(mci, KERN_ERR,
                        "could not look up page error address %lx\n",
                        (unsigned long)page);

        return row;
}
EXPORT_SYMBOL_GPL(edac_mc_find_csrow_by_page);

const char *edac_layer_name[] = {
        [EDAC_MC_LAYER_BRANCH] = "branch",
        [EDAC_MC_LAYER_CHANNEL] = "channel",
        [EDAC_MC_LAYER_SLOT] = "slot",
        [EDAC_MC_LAYER_CHIP_SELECT] = "csrow",
        [EDAC_MC_LAYER_ALL_MEM] = "memory",
};
EXPORT_SYMBOL_GPL(edac_layer_name);

static void edac_inc_ce_error(struct mem_ctl_info *mci,
                              bool enable_per_layer_report,
                              const int pos[EDAC_MAX_LAYERS],
                              const u16 count)
{
        int i, index = 0;

        mci->ce_mc += count;

        if (!enable_per_layer_report) {
                mci->ce_noinfo_count += count;
                return;
        }

        for (i = 0; i < mci->n_layers; i++) {
                if (pos[i] < 0)
                        break;
                index += pos[i];
                mci->ce_per_layer[i][index] += count;

                if (i < mci->n_layers - 1)
                        index *= mci->layers[i + 1].size;
        }
}

static void edac_inc_ue_error(struct mem_ctl_info *mci,
                                    bool enable_per_layer_report,
                                    const int pos[EDAC_MAX_LAYERS],
                                    const u16 count)
{
        int i, index = 0;

        mci->ue_mc += count;

        if (!enable_per_layer_report) {
                mci->ue_noinfo_count += count;
                return;
        }

        for (i = 0; i < mci->n_layers; i++) {
                if (pos[i] < 0)
                        break;
                index += pos[i];
                mci->ue_per_layer[i][index] += count;

                if (i < mci->n_layers - 1)
                        index *= mci->layers[i + 1].size;
        }
}

static void edac_ce_error(struct mem_ctl_info *mci,
                          const u16 error_count,
                          const int pos[EDAC_MAX_LAYERS],
                          const char *msg,
                          const char *location,
                          const char *label,
                          const char *detail,
                          const char *other_detail,
                          const bool enable_per_layer_report,
                          const unsigned long page_frame_number,
                          const unsigned long offset_in_page,
                          long grain)
{
        unsigned long remapped_page;
        char *msg_aux = "";

        if (*msg)
                msg_aux = " ";

        if (edac_mc_get_log_ce()) {
                if (other_detail && *other_detail)
                        edac_mc_printk(mci, KERN_WARNING,
                                       "%d CE %s%son %s (%s %s - %s)\n",
                                       error_count, msg, msg_aux, label,
                                       location, detail, other_detail);
                else
                        edac_mc_printk(mci, KERN_WARNING,
                                       "%d CE %s%son %s (%s %s)\n",
                                       error_count, msg, msg_aux, label,
                                       location, detail);
        }
        edac_inc_ce_error(mci, enable_per_layer_report, pos, error_count);

        if (mci->scrub_mode == SCRUB_SW_SRC) {
                /*
                        * Some memory controllers (called MCs below) can remap
                        * memory so that it is still available at a different
                        * address when PCI devices map into memory.
                        * MC's that can't do this, lose the memory where PCI
                        * devices are mapped. This mapping is MC-dependent
                        * and so we call back into the MC driver for it to
                        * map the MC page to a physical (CPU) page which can
                        * then be mapped to a virtual page - which can then
                        * be scrubbed.
                        */
                remapped_page = mci->ctl_page_to_phys ?
                        mci->ctl_page_to_phys(mci, page_frame_number) :
                        page_frame_number;

                edac_mc_scrub_block(remapped_page,
                                        offset_in_page, grain);
        }
}

static void edac_ue_error(struct mem_ctl_info *mci,
                          const u16 error_count,
                          const int pos[EDAC_MAX_LAYERS],
                          const char *msg,
                          const char *location,
                          const char *label,
                          const char *detail,
                          const char *other_detail,
                          const bool enable_per_layer_report)
{
        char *msg_aux = "";

        if (*msg)
                msg_aux = " ";

        if (edac_mc_get_log_ue()) {
                if (other_detail && *other_detail)
                        edac_mc_printk(mci, KERN_WARNING,
                                       "%d UE %s%son %s (%s %s - %s)\n",
                                       error_count, msg, msg_aux, label,
                                       location, detail, other_detail);
                else
                        edac_mc_printk(mci, KERN_WARNING,
                                       "%d UE %s%son %s (%s %s)\n",
                                       error_count, msg, msg_aux, label,
                                       location, detail);
        }

        if (edac_mc_get_panic_on_ue()) {
                if (other_detail && *other_detail)
                        panic("UE %s%son %s (%s%s - %s)\n",
                              msg, msg_aux, label, location, detail, other_detail);
                else
                        panic("UE %s%son %s (%s%s)\n",
                              msg, msg_aux, label, location, detail);
        }

        edac_inc_ue_error(mci, enable_per_layer_report, pos, error_count);
}

void edac_raw_mc_handle_error(const enum hw_event_mc_err_type type,
                              struct mem_ctl_info *mci,
                              struct edac_raw_error_desc *e)
{
        char detail[80];
        int pos[EDAC_MAX_LAYERS] = { e->top_layer, e->mid_layer, e->low_layer };

        /* Memory type dependent details about the error */
        if (type == HW_EVENT_ERR_CORRECTED) {
                snprintf(detail, sizeof(detail),
                        "page:0x%lx offset:0x%lx grain:%ld syndrome:0x%lx",
                        e->page_frame_number, e->offset_in_page,
                        e->grain, e->syndrome);
                edac_ce_error(mci, e->error_count, pos, e->msg, e->location, e->label,
                              detail, e->other_detail, e->enable_per_layer_report,
                              e->page_frame_number, e->offset_in_page, e->grain);
        } else {
                snprintf(detail, sizeof(detail),
                        "page:0x%lx offset:0x%lx grain:%ld",
                        e->page_frame_number, e->offset_in_page, e->grain);

                edac_ue_error(mci, e->error_count, pos, e->msg, e->location, e->label,
                              detail, e->other_detail, e->enable_per_layer_report);
        }


}
EXPORT_SYMBOL_GPL(edac_raw_mc_handle_error);

void edac_mc_handle_error(const enum hw_event_mc_err_type type,
                          struct mem_ctl_info *mci,
                          const u16 error_count,
                          const unsigned long page_frame_number,
                          const unsigned long offset_in_page,
                          const unsigned long syndrome,
                          const int top_layer,
                          const int mid_layer,
                          const int low_layer,
                          const char *msg,
                          const char *other_detail)
{
        char *p;
        int row = -1, chan = -1;
        int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer };
        int i, n_labels = 0;
        u8 grain_bits;
        struct edac_raw_error_desc *e = &mci->error_desc;

        edac_dbg(3, "MC%d\n", mci->mc_idx);

        /* Fills the error report buffer */
        memset(e, 0, sizeof (*e));
        e->error_count = error_count;
        e->top_layer = top_layer;
        e->mid_layer = mid_layer;
        e->low_layer = low_layer;
        e->page_frame_number = page_frame_number;
        e->offset_in_page = offset_in_page;
        e->syndrome = syndrome;
        e->msg = msg;
        e->other_detail = other_detail;

        /*
         * Check if the event report is consistent and if the memory
         * location is known. If it is known, enable_per_layer_report will be
         * true, the DIMM(s) label info will be filled and the per-layer
         * error counters will be incremented.
         */
        for (i = 0; i < mci->n_layers; i++) {
                if (pos[i] >= (int)mci->layers[i].size) {

                        edac_mc_printk(mci, KERN_ERR,
                                       "INTERNAL ERROR: %s value is out of range (%d >= %d)\n",
                                       edac_layer_name[mci->layers[i].type],
                                       pos[i], mci->layers[i].size);
                        /*
                         * Instead of just returning it, let's use what's
                         * known about the error. The increment routines and
                         * the DIMM filter logic will do the right thing by
                         * pointing the likely damaged DIMMs.
                         */
                        pos[i] = -1;
                }
                if (pos[i] >= 0)
                        e->enable_per_layer_report = true;
        }

        /*
         * Get the dimm label/grain that applies to the match criteria.
         * As the error algorithm may not be able to point to just one memory
         * stick, the logic here will get all possible labels that could
         * pottentially be affected by the error.
         * On FB-DIMM memory controllers, for uncorrected errors, it is common
         * to have only the MC channel and the MC dimm (also called "branch")
         * but the channel is not known, as the memory is arranged in pairs,
         * where each memory belongs to a separate channel within the same
         * branch.
         */
        p = e->label;
        *p = '\0';

        for (i = 0; i < mci->tot_dimms; i++) {
                struct dimm_info *dimm = mci->dimms[i];

                if (top_layer >= 0 && top_layer != dimm->location[0])
                        continue;
                if (mid_layer >= 0 && mid_layer != dimm->location[1])
                        continue;
                if (low_layer >= 0 && low_layer != dimm->location[2])
                        continue;

                /* get the max grain, over the error match range */
                if (dimm->grain > e->grain)
                        e->grain = dimm->grain;

                /*
                 * If the error is memory-controller wide, there's no need to
                 * seek for the affected DIMMs because the whole
                 * channel/memory controller/...  may be affected.
                 * Also, don't show errors for empty DIMM slots.
                 */
                if (e->enable_per_layer_report && dimm->nr_pages) {
                        if (n_labels >= EDAC_MAX_LABELS) {
                                e->enable_per_layer_report = false;
                                break;
                        }
                        n_labels++;
                        if (p != e->label) {
                                strcpy(p, OTHER_LABEL);
                                p += strlen(OTHER_LABEL);
                        }
                        strcpy(p, dimm->label);
                        p += strlen(p);
                        *p = '\0';

                        /*
                         * get csrow/channel of the DIMM, in order to allow
                         * incrementing the compat API counters
                         */
                        edac_dbg(4, "%s csrows map: (%d,%d)\n",
                                 mci->csbased ? "rank" : "dimm",
                                 dimm->csrow, dimm->cschannel);
                        if (row == -1)
                                row = dimm->csrow;
                        else if (row >= 0 && row != dimm->csrow)
                                row = -2;

                        if (chan == -1)
                                chan = dimm->cschannel;
                        else if (chan >= 0 && chan != dimm->cschannel)
                                chan = -2;
                }
        }

        if (!e->enable_per_layer_report) {
                strcpy(e->label, "any memory");
        } else {
                edac_dbg(4, "csrow/channel to increment: (%d,%d)\n", row, chan);
                if (p == e->label)
                        strcpy(e->label, "unknown memory");
                if (type == HW_EVENT_ERR_CORRECTED) {
                        if (row >= 0) {
                                mci->csrows[row]->ce_count += error_count;
                                if (chan >= 0)
                                        mci->csrows[row]->channels[chan]->ce_count += error_count;
                        }
                } else
                        if (row >= 0)
                                mci->csrows[row]->ue_count += error_count;
        }

        /* Fill the RAM location data */
        p = e->location;

        for (i = 0; i < mci->n_layers; i++) {
                if (pos[i] < 0)
                        continue;

                p += sprintf(p, "%s:%d ",
                             edac_layer_name[mci->layers[i].type],
                             pos[i]);
        }
        if (p > e->location)
                *(p - 1) = '\0';

        /* Report the error via the trace interface */
        grain_bits = fls_long(e->grain) + 1;

        if (IS_ENABLED(CONFIG_RAS))
                trace_mc_event(type, e->msg, e->label, e->error_count,
                               mci->mc_idx, e->top_layer, e->mid_layer,
                               e->low_layer,
                               (e->page_frame_number << PAGE_SHIFT) | e->offset_in_page,
                               grain_bits, e->syndrome, e->other_detail);

        edac_raw_mc_handle_error(type, mci, e);
}
EXPORT_SYMBOL_GPL(edac_mc_handle_error);