/*
 * Generic EDAC defs
 *
 * Author: Dave Jiang <djiang@mvista.com>
 *
 * 2006-2008 (c) MontaVista Software, Inc. This file is licensed under
 * the terms of the GNU General Public License version 2. This program
 * is licensed "as is" without any warranty of any kind, whether express
 * or implied.
 *
 */
#ifndef _LINUX_EDAC_H_
#define _LINUX_EDAC_H_

#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/completion.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/numa.h>

#define EDAC_DEVICE_NAME_LEN    31

struct device;

#define EDAC_OPSTATE_INVAL      -1
#define EDAC_OPSTATE_POLL       0
#define EDAC_OPSTATE_NMI        1
#define EDAC_OPSTATE_INT        2

extern int edac_op_state;

struct bus_type *edac_get_sysfs_subsys(void);

static inline void opstate_init(void)
{
        switch (edac_op_state) {
        case EDAC_OPSTATE_POLL:
        case EDAC_OPSTATE_NMI:
                break;
        default:
                edac_op_state = EDAC_OPSTATE_POLL;
        }
        return;
}

/* Max length of a DIMM label*/
#define EDAC_MC_LABEL_LEN       31

/* Maximum size of the location string */
#define LOCATION_SIZE 256

/* Defines the maximum number of labels that can be reported */
#define EDAC_MAX_LABELS         8

/* String used to join two or more labels */
#define OTHER_LABEL " or "

/**
 * enum dev_type - describe the type of memory DRAM chips used at the stick
 * @DEV_UNKNOWN:        Can't be determined, or MC doesn't support detect it
 * @DEV_X1:             1 bit for data
 * @DEV_X2:             2 bits for data
 * @DEV_X4:             4 bits for data
 * @DEV_X8:             8 bits for data
 * @DEV_X16:            16 bits for data
 * @DEV_X32:            32 bits for data
 * @DEV_X64:            64 bits for data
 *
 * Typical values are x4 and x8.
 */
enum dev_type {
        DEV_UNKNOWN = 0,
        DEV_X1,
        DEV_X2,
        DEV_X4,
        DEV_X8,
        DEV_X16,
        DEV_X32,                /* Do these parts exist? */
        DEV_X64                 /* Do these parts exist? */
};

#define DEV_FLAG_UNKNOWN        BIT(DEV_UNKNOWN)
#define DEV_FLAG_X1             BIT(DEV_X1)
#define DEV_FLAG_X2             BIT(DEV_X2)
#define DEV_FLAG_X4             BIT(DEV_X4)
#define DEV_FLAG_X8             BIT(DEV_X8)
#define DEV_FLAG_X16            BIT(DEV_X16)
#define DEV_FLAG_X32            BIT(DEV_X32)
#define DEV_FLAG_X64            BIT(DEV_X64)

/**
 * enum hw_event_mc_err_type - type of the detected error
 *
 * @HW_EVENT_ERR_CORRECTED:     Corrected Error - Indicates that an ECC
 *                              corrected error was detected
 * @HW_EVENT_ERR_UNCORRECTED:   Uncorrected Error - Indicates an error that
 *                              can't be corrected by ECC, but it is not
 *                              fatal (maybe it is on an unused memory area,
 *                              or the memory controller could recover from
 *                              it for example, by re-trying the operation).
 * @HW_EVENT_ERR_DEFERRED:      Deferred Error - Indicates an uncorrectable
 *                              error whose handling is not urgent. This could
 *                              be due to hardware data poisoning where the
 *                              system can continue operation until the poisoned
 *                              data is consumed. Preemptive measures may also
 *                              be taken, e.g. offlining pages, etc.
 * @HW_EVENT_ERR_FATAL:         Fatal Error - Uncorrected error that could not
 *                              be recovered.
 * @HW_EVENT_ERR_INFO:          Informational - The CPER spec defines a forth
 *                              type of error: informational logs.
 */
enum hw_event_mc_err_type {
        HW_EVENT_ERR_CORRECTED,
        HW_EVENT_ERR_UNCORRECTED,
        HW_EVENT_ERR_DEFERRED,
        HW_EVENT_ERR_FATAL,
        HW_EVENT_ERR_INFO,
};

static inline char *mc_event_error_type(const unsigned int err_type)
{
        switch (err_type) {
        case HW_EVENT_ERR_CORRECTED:
                return "Corrected";
        case HW_EVENT_ERR_UNCORRECTED:
                return "Uncorrected";
        case HW_EVENT_ERR_DEFERRED:
                return "Deferred";
        case HW_EVENT_ERR_FATAL:
                return "Fatal";
        default:
        case HW_EVENT_ERR_INFO:
                return "Info";
        }
}

/**
 * enum mem_type - memory types. For a more detailed reference, please see
 *                      http://en.wikipedia.org/wiki/DRAM
 *
 * @MEM_EMPTY:          Empty csrow
 * @MEM_RESERVED:       Reserved csrow type
 * @MEM_UNKNOWN:        Unknown csrow type
 * @MEM_FPM:            FPM - Fast Page Mode, used on systems up to 1995.
 * @MEM_EDO:            EDO - Extended data out, used on systems up to 1998.
 * @MEM_BEDO:           BEDO - Burst Extended data out, an EDO variant.
 * @MEM_SDR:            SDR - Single data rate SDRAM
 *                      http://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory
 *                      They use 3 pins for chip select: Pins 0 and 2 are
 *                      for rank 0; pins 1 and 3 are for rank 1, if the memory
 *                      is dual-rank.
 * @MEM_RDR:            Registered SDR SDRAM
 * @MEM_DDR:            Double data rate SDRAM
 *                      http://en.wikipedia.org/wiki/DDR_SDRAM
 * @MEM_RDDR:           Registered Double data rate SDRAM
 *                      This is a variant of the DDR memories.
 *                      A registered memory has a buffer inside it, hiding
 *                      part of the memory details to the memory controller.
 * @MEM_RMBS:           Rambus DRAM, used on a few Pentium III/IV controllers.
 * @MEM_DDR2:           DDR2 RAM, as described at JEDEC JESD79-2F.
 *                      Those memories are labeled as "PC2-" instead of "PC" to
 *                      differentiate from DDR.
 * @MEM_FB_DDR2:        Fully-Buffered DDR2, as described at JEDEC Std No. 205
 *                      and JESD206.
 *                      Those memories are accessed per DIMM slot, and not by
 *                      a chip select signal.
 * @MEM_RDDR2:          Registered DDR2 RAM
 *                      This is a variant of the DDR2 memories.
 * @MEM_XDR:            Rambus XDR
 *                      It is an evolution of the original RAMBUS memories,
 *                      created to compete with DDR2. Weren't used on any
 *                      x86 arch, but cell_edac PPC memory controller uses it.
 * @MEM_DDR3:           DDR3 RAM
 * @MEM_RDDR3:          Registered DDR3 RAM
 *                      This is a variant of the DDR3 memories.
 * @MEM_LRDDR3:         Load-Reduced DDR3 memory.
 * @MEM_LPDDR3:         Low-Power DDR3 memory.
 * @MEM_DDR4:           Unbuffered DDR4 RAM
 * @MEM_RDDR4:          Registered DDR4 RAM
 *                      This is a variant of the DDR4 memories.
 * @MEM_LRDDR4:         Load-Reduced DDR4 memory.
 * @MEM_LPDDR4:         Low-Power DDR4 memory.
 * @MEM_DDR5:           Unbuffered DDR5 RAM
 * @MEM_NVDIMM:         Non-volatile RAM
 * @MEM_WIO2:           Wide I/O 2.
 * @MEM_HBM2:           High bandwidth Memory Gen 2.
 */
enum mem_type {
        MEM_EMPTY = 0,
        MEM_RESERVED,
        MEM_UNKNOWN,
        MEM_FPM,
        MEM_EDO,
        MEM_BEDO,
        MEM_SDR,
        MEM_RDR,
        MEM_DDR,
        MEM_RDDR,
        MEM_RMBS,
        MEM_DDR2,
        MEM_FB_DDR2,
        MEM_RDDR2,
        MEM_XDR,
        MEM_DDR3,
        MEM_RDDR3,
        MEM_LRDDR3,
        MEM_LPDDR3,
        MEM_DDR4,
        MEM_RDDR4,
        MEM_LRDDR4,
        MEM_LPDDR4,
        MEM_DDR5,
        MEM_NVDIMM,
        MEM_WIO2,
        MEM_HBM2,
};

#define MEM_FLAG_EMPTY          BIT(MEM_EMPTY)
#define MEM_FLAG_RESERVED       BIT(MEM_RESERVED)
#define MEM_FLAG_UNKNOWN        BIT(MEM_UNKNOWN)
#define MEM_FLAG_FPM            BIT(MEM_FPM)
#define MEM_FLAG_EDO            BIT(MEM_EDO)
#define MEM_FLAG_BEDO           BIT(MEM_BEDO)
#define MEM_FLAG_SDR            BIT(MEM_SDR)
#define MEM_FLAG_RDR            BIT(MEM_RDR)
#define MEM_FLAG_DDR            BIT(MEM_DDR)
#define MEM_FLAG_RDDR           BIT(MEM_RDDR)
#define MEM_FLAG_RMBS           BIT(MEM_RMBS)
#define MEM_FLAG_DDR2           BIT(MEM_DDR2)
#define MEM_FLAG_FB_DDR2        BIT(MEM_FB_DDR2)
#define MEM_FLAG_RDDR2          BIT(MEM_RDDR2)
#define MEM_FLAG_XDR            BIT(MEM_XDR)
#define MEM_FLAG_DDR3           BIT(MEM_DDR3)
#define MEM_FLAG_RDDR3          BIT(MEM_RDDR3)
#define MEM_FLAG_LPDDR3         BIT(MEM_LPDDR3)
#define MEM_FLAG_DDR4           BIT(MEM_DDR4)
#define MEM_FLAG_RDDR4          BIT(MEM_RDDR4)
#define MEM_FLAG_LRDDR4         BIT(MEM_LRDDR4)
#define MEM_FLAG_LPDDR4         BIT(MEM_LPDDR4)
#define MEM_FLAG_DDR5           BIT(MEM_DDR5)
#define MEM_FLAG_NVDIMM         BIT(MEM_NVDIMM)
#define MEM_FLAG_WIO2           BIT(MEM_WIO2)
#define MEM_FLAG_HBM2           BIT(MEM_HBM2)

/**
 * enum edac_type - Error Detection and Correction capabilities and mode
 * @EDAC_UNKNOWN:       Unknown if ECC is available
 * @EDAC_NONE:          Doesn't support ECC
 * @EDAC_RESERVED:      Reserved ECC type
 * @EDAC_PARITY:        Detects parity errors
 * @EDAC_EC:            Error Checking - no correction
 * @EDAC_SECDED:        Single bit error correction, Double detection
 * @EDAC_S2ECD2ED:      Chipkill x2 devices - do these exist?
 * @EDAC_S4ECD4ED:      Chipkill x4 devices
 * @EDAC_S8ECD8ED:      Chipkill x8 devices
 * @EDAC_S16ECD16ED:    Chipkill x16 devices
 */
enum edac_type {
        EDAC_UNKNOWN =  0,
        EDAC_NONE,
        EDAC_RESERVED,
        EDAC_PARITY,
        EDAC_EC,
        EDAC_SECDED,
        EDAC_S2ECD2ED,
        EDAC_S4ECD4ED,
        EDAC_S8ECD8ED,
        EDAC_S16ECD16ED,
};

#define EDAC_FLAG_UNKNOWN       BIT(EDAC_UNKNOWN)
#define EDAC_FLAG_NONE          BIT(EDAC_NONE)
#define EDAC_FLAG_PARITY        BIT(EDAC_PARITY)
#define EDAC_FLAG_EC            BIT(EDAC_EC)
#define EDAC_FLAG_SECDED        BIT(EDAC_SECDED)
#define EDAC_FLAG_S2ECD2ED      BIT(EDAC_S2ECD2ED)
#define EDAC_FLAG_S4ECD4ED      BIT(EDAC_S4ECD4ED)
#define EDAC_FLAG_S8ECD8ED      BIT(EDAC_S8ECD8ED)
#define EDAC_FLAG_S16ECD16ED    BIT(EDAC_S16ECD16ED)

/**
 * enum scrub_type - scrubbing capabilities
 * @SCRUB_UNKNOWN:              Unknown if scrubber is available
 * @SCRUB_NONE:                 No scrubber
 * @SCRUB_SW_PROG:              SW progressive (sequential) scrubbing
 * @SCRUB_SW_SRC:               Software scrub only errors
 * @SCRUB_SW_PROG_SRC:          Progressive software scrub from an error
 * @SCRUB_SW_TUNABLE:           Software scrub frequency is tunable
 * @SCRUB_HW_PROG:              HW progressive (sequential) scrubbing
 * @SCRUB_HW_SRC:               Hardware scrub only errors
 * @SCRUB_HW_PROG_SRC:          Progressive hardware scrub from an error
 * @SCRUB_HW_TUNABLE:           Hardware scrub frequency is tunable
 */
enum scrub_type {
        SCRUB_UNKNOWN = 0,
        SCRUB_NONE,
        SCRUB_SW_PROG,
        SCRUB_SW_SRC,
        SCRUB_SW_PROG_SRC,
        SCRUB_SW_TUNABLE,
        SCRUB_HW_PROG,
        SCRUB_HW_SRC,
        SCRUB_HW_PROG_SRC,
        SCRUB_HW_TUNABLE
};

#define SCRUB_FLAG_SW_PROG      BIT(SCRUB_SW_PROG)
#define SCRUB_FLAG_SW_SRC       BIT(SCRUB_SW_SRC)
#define SCRUB_FLAG_SW_PROG_SRC  BIT(SCRUB_SW_PROG_SRC)
#define SCRUB_FLAG_SW_TUN       BIT(SCRUB_SW_SCRUB_TUNABLE)
#define SCRUB_FLAG_HW_PROG      BIT(SCRUB_HW_PROG)
#define SCRUB_FLAG_HW_SRC       BIT(SCRUB_HW_SRC)
#define SCRUB_FLAG_HW_PROG_SRC  BIT(SCRUB_HW_PROG_SRC)
#define SCRUB_FLAG_HW_TUN       BIT(SCRUB_HW_TUNABLE)

/* FIXME - should have notify capabilities: NMI, LOG, PROC, etc */

/* EDAC internal operation states */
#define OP_ALLOC                0x100
#define OP_RUNNING_POLL         0x201
#define OP_RUNNING_INTERRUPT    0x202
#define OP_RUNNING_POLL_INTR    0x203
#define OP_OFFLINE              0x300

/**
 * enum edac_mc_layer_type - memory controller hierarchy layer
 *
 * @EDAC_MC_LAYER_BRANCH:       memory layer is named "branch"
 * @EDAC_MC_LAYER_CHANNEL:      memory layer is named "channel"
 * @EDAC_MC_LAYER_SLOT:         memory layer is named "slot"
 * @EDAC_MC_LAYER_CHIP_SELECT:  memory layer is named "chip select"
 * @EDAC_MC_LAYER_ALL_MEM:      memory layout is unknown. All memory is mapped
 *                              as a single memory area. This is used when
 *                              retrieving errors from a firmware driven driver.
 *
 * This enum is used by the drivers to tell edac_mc_sysfs what name should
 * be used when describing a memory stick location.
 */
enum edac_mc_layer_type {
        EDAC_MC_LAYER_BRANCH,
        EDAC_MC_LAYER_CHANNEL,
        EDAC_MC_LAYER_SLOT,
        EDAC_MC_LAYER_CHIP_SELECT,
        EDAC_MC_LAYER_ALL_MEM,
};

/**
 * struct edac_mc_layer - describes the memory controller hierarchy
 * @type:               layer type
 * @size:               number of components per layer. For example,
 *                      if the channel layer has two channels, size = 2
 * @is_virt_csrow:      This layer is part of the "csrow" when old API
 *                      compatibility mode is enabled. Otherwise, it is
 *                      a channel
 */
struct edac_mc_layer {
        enum edac_mc_layer_type type;
        unsigned                size;
        bool                    is_virt_csrow;
};

/*
 * Maximum number of layers used by the memory controller to uniquely
 * identify a single memory stick.
 * NOTE: Changing this constant requires not only to change the constant
 * below, but also to change the existing code at the core, as there are
 * some code there that are optimized for 3 layers.
 */
#define EDAC_MAX_LAYERS         3

struct dimm_info {
        struct device dev;

        char label[EDAC_MC_LABEL_LEN + 1];      /* DIMM label on motherboard */

        /* Memory location data */
        unsigned int location[EDAC_MAX_LAYERS];

        struct mem_ctl_info *mci;       /* the parent */
        unsigned int idx;               /* index within the parent dimm array */

        u32 grain;              /* granularity of reported error in bytes */
        enum dev_type dtype;    /* memory device type */
        enum mem_type mtype;    /* memory dimm type */
        enum edac_type edac_mode;       /* EDAC mode for this dimm */

        u32 nr_pages;                   /* number of pages on this dimm */

        unsigned int csrow, cschannel;  /* Points to the old API data */

        u16 smbios_handle;              /* Handle for SMBIOS type 17 */

        u32 ce_count;
        u32 ue_count;
};

/**
 * struct rank_info - contains the information for one DIMM rank
 *
 * @chan_idx:   channel number where the rank is (typically, 0 or 1)
 * @ce_count:   number of correctable errors for this rank
 * @csrow:      A pointer to the chip select row structure (the parent
 *              structure). The location of the rank is given by
 *              the (csrow->csrow_idx, chan_idx) vector.
 * @dimm:       A pointer to the DIMM structure, where the DIMM label
 *              information is stored.
 *
 * FIXME: Currently, the EDAC core model will assume one DIMM per rank.
 *        This is a bad assumption, but it makes this patch easier. Later
 *        patches in this series will fix this issue.
 */
struct rank_info {
        int chan_idx;
        struct csrow_info *csrow;
        struct dimm_info *dimm;

        u32 ce_count;           /* Correctable Errors for this csrow */
};

struct csrow_info {
        struct device dev;

        /* Used only by edac_mc_find_csrow_by_page() */
        unsigned long first_page;       /* first page number in csrow */
        unsigned long last_page;        /* last page number in csrow */
        unsigned long page_mask;        /* used for interleaving -
                                         * 0UL for non intlv */

        int csrow_idx;                  /* the chip-select row */

        u32 ue_count;           /* Uncorrectable Errors for this csrow */
        u32 ce_count;           /* Correctable Errors for this csrow */

        struct mem_ctl_info *mci;       /* the parent */

        /* channel information for this csrow */
        u32 nr_channels;
        struct rank_info **channels;
};

/*
 * struct errcount_attribute - used to store the several error counts
 */
struct errcount_attribute_data {
        int n_layers;
        int pos[EDAC_MAX_LAYERS];
        int layer0, layer1, layer2;
};

/**
 * struct edac_raw_error_desc - Raw error report structure
 * @grain:                      minimum granularity for an error report, in bytes
 * @error_count:                number of errors of the same type
 * @type:                       severity of the error (CE/UE/Fatal)
 * @top_layer:                  top layer of the error (layer[0])
 * @mid_layer:                  middle layer of the error (layer[1])
 * @low_layer:                  low layer of the error (layer[2])
 * @page_frame_number:          page where the error happened
 * @offset_in_page:             page offset
 * @syndrome:                   syndrome of the error (or 0 if unknown or if
 *                              the syndrome is not applicable)
 * @msg:                        error message
 * @location:                   location of the error
 * @label:                      label of the affected DIMM(s)
 * @other_detail:               other driver-specific detail about the error
 */
struct edac_raw_error_desc {
        char location[LOCATION_SIZE];
        char label[(EDAC_MC_LABEL_LEN + 1 + sizeof(OTHER_LABEL)) * EDAC_MAX_LABELS];
        long grain;

        u16 error_count;
        enum hw_event_mc_err_type type;
        int top_layer;
        int mid_layer;
        int low_layer;
        unsigned long page_frame_number;
        unsigned long offset_in_page;
        unsigned long syndrome;
        const char *msg;
        const char *other_detail;
};

/* MEMORY controller information structure
 */
struct mem_ctl_info {
        struct device                   dev;
        struct bus_type                 *bus;

        struct list_head link;  /* for global list of mem_ctl_info structs */

        struct module *owner;   /* Module owner of this control struct */

        unsigned long mtype_cap;        /* memory types supported by mc */
        unsigned long edac_ctl_cap;     /* Mem controller EDAC capabilities */
        unsigned long edac_cap; /* configuration capabilities - this is
                                 * closely related to edac_ctl_cap.  The
                                 * difference is that the controller may be
                                 * capable of s4ecd4ed which would be listed
                                 * in edac_ctl_cap, but if channels aren't
                                 * capable of s4ecd4ed then the edac_cap would
                                 * not have that capability.
                                 */
        unsigned long scrub_cap;        /* chipset scrub capabilities */
        enum scrub_type scrub_mode;     /* current scrub mode */

        /* Translates sdram memory scrub rate given in bytes/sec to the
           internal representation and configures whatever else needs
           to be configured.
         */
        int (*set_sdram_scrub_rate) (struct mem_ctl_info * mci, u32 bw);

        /* Get the current sdram memory scrub rate from the internal
           representation and converts it to the closest matching
           bandwidth in bytes/sec.
         */
        int (*get_sdram_scrub_rate) (struct mem_ctl_info * mci);


        /* pointer to edac checking routine */
        void (*edac_check) (struct mem_ctl_info * mci);

        /*
         * Remaps memory pages: controller pages to physical pages.
         * For most MC's, this will be NULL.
         */
        /* FIXME - why not send the phys page to begin with? */
        unsigned long (*ctl_page_to_phys) (struct mem_ctl_info * mci,
                                           unsigned long page);
        int mc_idx;
        struct csrow_info **csrows;
        unsigned int nr_csrows, num_cschannel;

        /*
         * Memory Controller hierarchy
         *
         * There are basically two types of memory controller: the ones that
         * sees memory sticks ("dimms"), and the ones that sees memory ranks.
         * All old memory controllers enumerate memories per rank, but most
         * of the recent drivers enumerate memories per DIMM, instead.
         * When the memory controller is per rank, csbased is true.
         */
        unsigned int n_layers;
        struct edac_mc_layer *layers;
        bool csbased;

        /*
         * DIMM info. Will eventually remove the entire csrows_info some day
         */
        unsigned int tot_dimms;
        struct dimm_info **dimms;

        /*
         * FIXME - what about controllers on other busses? - IDs must be
         * unique.  dev pointer should be sufficiently unique, but
         * BUS:SLOT.FUNC numbers may not be unique.
         */
        struct device *pdev;
        const char *mod_name;
        const char *ctl_name;
        const char *dev_name;
        void *pvt_info;
        unsigned long start_time;       /* mci load start time (in jiffies) */

        /*
         * drivers shouldn't access those fields directly, as the core
         * already handles that.
         */
        u32 ce_noinfo_count, ue_noinfo_count;
        u32 ue_mc, ce_mc;

        struct completion complete;

        /* Additional top controller level attributes, but specified
         * by the low level driver.
         *
         * Set by the low level driver to provide attributes at the
         * controller level.
         * An array of structures, NULL terminated
         *
         * If attributes are desired, then set to array of attributes
         * If no attributes are desired, leave NULL
         */
        const struct mcidev_sysfs_attribute *mc_driver_sysfs_attributes;

        /* work struct for this MC */
        struct delayed_work work;

        /*
         * Used to report an error - by being at the global struct
         * makes the memory allocated by the EDAC core
         */
        struct edac_raw_error_desc error_desc;

        /* the internal state of this controller instance */
        int op_state;

        struct dentry *debugfs;
        u8 fake_inject_layer[EDAC_MAX_LAYERS];
        bool fake_inject_ue;
        u16 fake_inject_count;
};

#define mci_for_each_dimm(mci, dimm)                            \
        for ((dimm) = (mci)->dimms[0];                          \
             (dimm);                                            \
             (dimm) = (dimm)->idx + 1 < (mci)->tot_dimms        \
                     ? (mci)->dimms[(dimm)->idx + 1]            \
                     : NULL)

/**
 * edac_get_dimm - Get DIMM info from a memory controller given by
 *                 [layer0,layer1,layer2] position
 *
 * @mci:        MC descriptor struct mem_ctl_info
 * @layer0:     layer0 position
 * @layer1:     layer1 position. Unused if n_layers < 2
 * @layer2:     layer2 position. Unused if n_layers < 3
 *
 * For 1 layer, this function returns "dimms[layer0]";
 *
 * For 2 layers, this function is similar to allocating a two-dimensional
 * array and returning "dimms[layer0][layer1]";
 *
 * For 3 layers, this function is similar to allocating a tri-dimensional
 * array and returning "dimms[layer0][layer1][layer2]";
 */
static inline struct dimm_info *edac_get_dimm(struct mem_ctl_info *mci,
        int layer0, int layer1, int layer2)
{
        int index;

        if (layer0 < 0
            || (mci->n_layers > 1 && layer1 < 0)
            || (mci->n_layers > 2 && layer2 < 0))
                return NULL;

        index = layer0;

        if (mci->n_layers > 1)
                index = index * mci->layers[1].size + layer1;

        if (mci->n_layers > 2)
                index = index * mci->layers[2].size + layer2;

        if (index < 0 || index >= mci->tot_dimms)
                return NULL;

        if (WARN_ON_ONCE(mci->dimms[index]->idx != index))
                return NULL;

        return mci->dimms[index];
}
#endif /* _LINUX_EDAC_H_ */