/*
 * Intel X38 Memory Controller kernel module
 * Copyright (C) 2008 Cluster Computing, Inc.
 *
 * This file may be distributed under the terms of the
 * GNU General Public License.
 *
 * This file is based on i3200_edac.c
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
#include <linux/slab.h>
#include <linux/edac.h>
#include "edac_core.h"

#define X38_REVISION            "1.1"

#define EDAC_MOD_STR            "x38_edac"

#define PCI_DEVICE_ID_INTEL_X38_HB      0x29e0

#define X38_RANKS               8
#define X38_RANKS_PER_CHANNEL   4
#define X38_CHANNELS            2

/* Intel X38 register addresses - device 0 function 0 - DRAM Controller */

#define X38_MCHBAR_LOW  0x48    /* MCH Memory Mapped Register BAR */
#define X38_MCHBAR_HIGH 0x4b
#define X38_MCHBAR_MASK 0xfffffc000ULL  /* bits 35:14 */
#define X38_MMR_WINDOW_SIZE     16384

#define X38_TOM 0xa0    /* Top of Memory (16b)
                                 *
                                 * 15:10 reserved
                                 *  9:0  total populated physical memory
                                 */
#define X38_TOM_MASK    0x3ff   /* bits 9:0 */
#define X38_TOM_SHIFT 26        /* 64MiB grain */

#define X38_ERRSTS      0xc8    /* Error Status Register (16b)
                                 *
                                 * 15    reserved
                                 * 14    Isochronous TBWRR Run Behind FIFO Full
                                 *       (ITCV)
                                 * 13    Isochronous TBWRR Run Behind FIFO Put
                                 *       (ITSTV)
                                 * 12    reserved
                                 * 11    MCH Thermal Sensor Event
                                 *       for SMI/SCI/SERR (GTSE)
                                 * 10    reserved
                                 *  9    LOCK to non-DRAM Memory Flag (LCKF)
                                 *  8    reserved
                                 *  7    DRAM Throttle Flag (DTF)
                                 *  6:2  reserved
                                 *  1    Multi-bit DRAM ECC Error Flag (DMERR)
                                 *  0    Single-bit DRAM ECC Error Flag (DSERR)
                                 */
#define X38_ERRSTS_UE           0x0002
#define X38_ERRSTS_CE           0x0001
#define X38_ERRSTS_BITS (X38_ERRSTS_UE | X38_ERRSTS_CE)


/* Intel  MMIO register space - device 0 function 0 - MMR space */

#define X38_C0DRB       0x200   /* Channel 0 DRAM Rank Boundary (16b x 4)
                                 *
                                 * 15:10 reserved
                                 *  9:0  Channel 0 DRAM Rank Boundary Address
                                 */
#define X38_C1DRB       0x600   /* Channel 1 DRAM Rank Boundary (16b x 4) */
#define X38_DRB_MASK    0x3ff   /* bits 9:0 */
#define X38_DRB_SHIFT 26        /* 64MiB grain */

#define X38_C0ECCERRLOG 0x280   /* Channel 0 ECC Error Log (64b)
                                 *
                                 * 63:48 Error Column Address (ERRCOL)
                                 * 47:32 Error Row Address (ERRROW)
                                 * 31:29 Error Bank Address (ERRBANK)
                                 * 28:27 Error Rank Address (ERRRANK)
                                 * 26:24 reserved
                                 * 23:16 Error Syndrome (ERRSYND)
                                 * 15: 2 reserved
                                 *    1  Multiple Bit Error Status (MERRSTS)
                                 *    0  Correctable Error Status (CERRSTS)
                                 */
#define X38_C1ECCERRLOG 0x680   /* Channel 1 ECC Error Log (64b) */
#define X38_ECCERRLOG_CE        0x1
#define X38_ECCERRLOG_UE        0x2
#define X38_ECCERRLOG_RANK_BITS 0x18000000
#define X38_ECCERRLOG_SYNDROME_BITS     0xff0000

#define X38_CAPID0 0xe0 /* see P.94 of spec for details */

static int x38_channel_num;

static int how_many_channel(struct pci_dev *pdev)
{
        unsigned char capid0_8b; /* 8th byte of CAPID0 */

        pci_read_config_byte(pdev, X38_CAPID0 + 8, &capid0_8b);
        if (capid0_8b & 0x20) { /* check DCD: Dual Channel Disable */
                debugf0("In single channel mode.\n");
                x38_channel_num = 1;
        } else {
                debugf0("In dual channel mode.\n");
                x38_channel_num = 2;
        }

        return x38_channel_num;
}

static unsigned long eccerrlog_syndrome(u64 log)
{
        return (log & X38_ECCERRLOG_SYNDROME_BITS) >> 16;
}

static int eccerrlog_row(int channel, u64 log)
{
        return ((log & X38_ECCERRLOG_RANK_BITS) >> 27) |
                (channel * X38_RANKS_PER_CHANNEL);
}

enum x38_chips {
        X38 = 0,
};

struct x38_dev_info {
        const char *ctl_name;
};

struct x38_error_info {
        u16 errsts;
        u16 errsts2;
        u64 eccerrlog[X38_CHANNELS];
};

static const struct x38_dev_info x38_devs[] = {
        [X38] = {
                .ctl_name = "x38"},
};

static struct pci_dev *mci_pdev;
static int x38_registered = 1;


static void x38_clear_error_info(struct mem_ctl_info *mci)
{
        struct pci_dev *pdev;

        pdev = to_pci_dev(mci->dev);

        /*
         * Clear any error bits.
         * (Yes, we really clear bits by writing 1 to them.)
         */
        pci_write_bits16(pdev, X38_ERRSTS, X38_ERRSTS_BITS,
                         X38_ERRSTS_BITS);
}

static u64 x38_readq(const void __iomem *addr)
{
        return readl(addr) | (((u64)readl(addr + 4)) << 32);
}

static void x38_get_and_clear_error_info(struct mem_ctl_info *mci,
                                 struct x38_error_info *info)
{
        struct pci_dev *pdev;
        void __iomem *window = mci->pvt_info;

        pdev = to_pci_dev(mci->dev);

        /*
         * This is a mess because there is no atomic way to read all the
         * registers at once and the registers can transition from CE being
         * overwritten by UE.
         */
        pci_read_config_word(pdev, X38_ERRSTS, &info->errsts);
        if (!(info->errsts & X38_ERRSTS_BITS))
                return;

        info->eccerrlog[0] = x38_readq(window + X38_C0ECCERRLOG);
        if (x38_channel_num == 2)
                info->eccerrlog[1] = x38_readq(window + X38_C1ECCERRLOG);

        pci_read_config_word(pdev, X38_ERRSTS, &info->errsts2);

        /*
         * If the error is the same for both reads then the first set
         * of reads is valid.  If there is a change then there is a CE
         * with no info and the second set of reads is valid and
         * should be UE info.
         */
        if ((info->errsts ^ info->errsts2) & X38_ERRSTS_BITS) {
                info->eccerrlog[0] = x38_readq(window + X38_C0ECCERRLOG);
                if (x38_channel_num == 2)
                        info->eccerrlog[1] =
                                x38_readq(window + X38_C1ECCERRLOG);
        }

        x38_clear_error_info(mci);
}

static void x38_process_error_info(struct mem_ctl_info *mci,
                                struct x38_error_info *info)
{
        int channel;
        u64 log;

        if (!(info->errsts & X38_ERRSTS_BITS))
                return;

        if ((info->errsts ^ info->errsts2) & X38_ERRSTS_BITS) {
                edac_mc_handle_ce_no_info(mci, "UE overwrote CE");
                info->errsts = info->errsts2;
        }

        for (channel = 0; channel < x38_channel_num; channel++) {
                log = info->eccerrlog[channel];
                if (log & X38_ECCERRLOG_UE) {
                        edac_mc_handle_ue(mci, 0, 0,
                                eccerrlog_row(channel, log), "x38 UE");
                } else if (log & X38_ECCERRLOG_CE) {
                        edac_mc_handle_ce(mci, 0, 0,
                                eccerrlog_syndrome(log),
                                eccerrlog_row(channel, log), 0, "x38 CE");
                }
        }
}

static void x38_check(struct mem_ctl_info *mci)
{
        struct x38_error_info info;

        debugf1("MC%d: %s()\n", mci->mc_idx, __func__);
        x38_get_and_clear_error_info(mci, &info);
        x38_process_error_info(mci, &info);
}


void __iomem *x38_map_mchbar(struct pci_dev *pdev)
{
        union {
                u64 mchbar;
                struct {
                        u32 mchbar_low;
                        u32 mchbar_high;
                };
        } u;
        void __iomem *window;

        pci_read_config_dword(pdev, X38_MCHBAR_LOW, &u.mchbar_low);
        pci_write_config_dword(pdev, X38_MCHBAR_LOW, u.mchbar_low | 0x1);
        pci_read_config_dword(pdev, X38_MCHBAR_HIGH, &u.mchbar_high);
        u.mchbar &= X38_MCHBAR_MASK;

        if (u.mchbar != (resource_size_t)u.mchbar) {
                printk(KERN_ERR
                        "x38: mmio space beyond accessible range (0x%llx)\n",
                        (unsigned long long)u.mchbar);
                return NULL;
        }

        window = ioremap_nocache(u.mchbar, X38_MMR_WINDOW_SIZE);
        if (!window)
                printk(KERN_ERR "x38: cannot map mmio space at 0x%llx\n",
                        (unsigned long long)u.mchbar);

        return window;
}


static void x38_get_drbs(void __iomem *window,
                        u16 drbs[X38_CHANNELS][X38_RANKS_PER_CHANNEL])
{
        int i;

        for (i = 0; i < X38_RANKS_PER_CHANNEL; i++) {
                drbs[0][i] = readw(window + X38_C0DRB + 2*i) & X38_DRB_MASK;
                drbs[1][i] = readw(window + X38_C1DRB + 2*i) & X38_DRB_MASK;
        }
}

static bool x38_is_stacked(struct pci_dev *pdev,
                        u16 drbs[X38_CHANNELS][X38_RANKS_PER_CHANNEL])
{
        u16 tom;

        pci_read_config_word(pdev, X38_TOM, &tom);
        tom &= X38_TOM_MASK;

        return drbs[X38_CHANNELS - 1][X38_RANKS_PER_CHANNEL - 1] == tom;
}

static unsigned long drb_to_nr_pages(
                        u16 drbs[X38_CHANNELS][X38_RANKS_PER_CHANNEL],
                        bool stacked, int channel, int rank)
{
        int n;

        n = drbs[channel][rank];
        if (rank > 0)
                n -= drbs[channel][rank - 1];
        if (stacked && (channel == 1) && drbs[channel][rank] ==
                                drbs[channel][X38_RANKS_PER_CHANNEL - 1]) {
                n -= drbs[0][X38_RANKS_PER_CHANNEL - 1];
        }

        n <<= (X38_DRB_SHIFT - PAGE_SHIFT);
        return n;
}

static int x38_probe1(struct pci_dev *pdev, int dev_idx)
{
        int rc;
        int i;
        struct mem_ctl_info *mci = NULL;
        unsigned long last_page;
        u16 drbs[X38_CHANNELS][X38_RANKS_PER_CHANNEL];
        bool stacked;
        void __iomem *window;

        debugf0("MC: %s()\n", __func__);

        window = x38_map_mchbar(pdev);
        if (!window)
                return -ENODEV;

        x38_get_drbs(window, drbs);

        how_many_channel(pdev);

        /* FIXME: unconventional pvt_info usage */
        mci = edac_mc_alloc(0, X38_RANKS, x38_channel_num, 0);
        if (!mci)
                return -ENOMEM;

        debugf3("MC: %s(): init mci\n", __func__);

        mci->dev = &pdev->dev;
        mci->mtype_cap = MEM_FLAG_DDR2;

        mci->edac_ctl_cap = EDAC_FLAG_SECDED;
        mci->edac_cap = EDAC_FLAG_SECDED;

        mci->mod_name = EDAC_MOD_STR;
        mci->mod_ver = X38_REVISION;
        mci->ctl_name = x38_devs[dev_idx].ctl_name;
        mci->dev_name = pci_name(pdev);
        mci->edac_check = x38_check;
        mci->ctl_page_to_phys = NULL;
        mci->pvt_info = window;

        stacked = x38_is_stacked(pdev, drbs);

        /*
         * The dram rank boundary (DRB) reg values are boundary addresses
         * for each DRAM rank with a granularity of 64MB.  DRB regs are
         * cumulative; the last one will contain the total memory
         * contained in all ranks.
         */
        last_page = -1UL;
        for (i = 0; i < mci->nr_csrows; i++) {
                unsigned long nr_pages;
                struct csrow_info *csrow = &mci->csrows[i];

                nr_pages = drb_to_nr_pages(drbs, stacked,
                        i / X38_RANKS_PER_CHANNEL,
                        i % X38_RANKS_PER_CHANNEL);

                if (nr_pages == 0) {
                        csrow->mtype = MEM_EMPTY;
                        continue;
                }

                csrow->first_page = last_page + 1;
                last_page += nr_pages;
                csrow->last_page = last_page;
                csrow->nr_pages = nr_pages;

                csrow->grain = nr_pages << PAGE_SHIFT;
                csrow->mtype = MEM_DDR2;
                csrow->dtype = DEV_UNKNOWN;
                csrow->edac_mode = EDAC_UNKNOWN;
        }

        x38_clear_error_info(mci);

        rc = -ENODEV;
        if (edac_mc_add_mc(mci)) {
                debugf3("MC: %s(): failed edac_mc_add_mc()\n", __func__);
                goto fail;
        }

        /* get this far and it's successful */
        debugf3("MC: %s(): success\n", __func__);
        return 0;

fail:
        iounmap(window);
        if (mci)
                edac_mc_free(mci);

        return rc;
}

static int __devinit x38_init_one(struct pci_dev *pdev,
                                const struct pci_device_id *ent)
{
        int rc;

        debugf0("MC: %s()\n", __func__);

        if (pci_enable_device(pdev) < 0)
                return -EIO;

        rc = x38_probe1(pdev, ent->driver_data);
        if (!mci_pdev)
                mci_pdev = pci_dev_get(pdev);

        return rc;
}

static void __devexit x38_remove_one(struct pci_dev *pdev)
{
        struct mem_ctl_info *mci;

        debugf0("%s()\n", __func__);

        mci = edac_mc_del_mc(&pdev->dev);
        if (!mci)
                return;

        iounmap(mci->pvt_info);

        edac_mc_free(mci);
}

static const struct pci_device_id x38_pci_tbl[] __devinitdata = {
        {
         PCI_VEND_DEV(INTEL, X38_HB), PCI_ANY_ID, PCI_ANY_ID, 0, 0,
         X38},
        {
         0,
         }                      /* 0 terminated list. */
};

MODULE_DEVICE_TABLE(pci, x38_pci_tbl);

static struct pci_driver x38_driver = {
        .name = EDAC_MOD_STR,
        .probe = x38_init_one,
        .remove = __devexit_p(x38_remove_one),
        .id_table = x38_pci_tbl,
};

static int __init x38_init(void)
{
        int pci_rc;

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

        /* Ensure that the OPSTATE is set correctly for POLL or NMI */
        opstate_init();

        pci_rc = pci_register_driver(&x38_driver);
        if (pci_rc < 0)
                goto fail0;

        if (!mci_pdev) {
                x38_registered = 0;
                mci_pdev = pci_get_device(PCI_VENDOR_ID_INTEL,
                                        PCI_DEVICE_ID_INTEL_X38_HB, NULL);
                if (!mci_pdev) {
                        debugf0("x38 pci_get_device fail\n");
                        pci_rc = -ENODEV;
                        goto fail1;
                }

                pci_rc = x38_init_one(mci_pdev, x38_pci_tbl);
                if (pci_rc < 0) {
                        debugf0("x38 init fail\n");
                        pci_rc = -ENODEV;
                        goto fail1;
                }
        }

        return 0;

fail1:
        pci_unregister_driver(&x38_driver);

fail0:
        if (mci_pdev)
                pci_dev_put(mci_pdev);

        return pci_rc;
}

static void __exit x38_exit(void)
{
        debugf3("MC: %s()\n", __func__);

        pci_unregister_driver(&x38_driver);
        if (!x38_registered) {
                x38_remove_one(mci_pdev);
                pci_dev_put(mci_pdev);
        }
}

module_init(x38_init);
module_exit(x38_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Cluster Computing, Inc. Hitoshi Mitake");
MODULE_DESCRIPTION("MC support for Intel X38 memory hub controllers");

module_param(edac_op_state, int, 0444);
MODULE_PARM_DESC(edac_op_state, "EDAC Error Reporting state: 0=Poll,1=NMI");