/*
 * Intel 82975X Memory Controller kernel module
 * (C) 2007 aCarLab (India) Pvt. Ltd. (http://acarlab.com)
 * (C) 2007 jetzbroadband (http://jetzbroadband.com)
 * This file may be distributed under the terms of the
 * GNU General Public License.
 *
 * Written by Arvind R.
 *   Copied from i82875p_edac.c source:
 */

#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 I82975X_REVISION        " Ver: 1.0.0 " __DATE__
#define EDAC_MOD_STR            "i82975x_edac"

#define i82975x_printk(level, fmt, arg...) \
        edac_printk(level, "i82975x", fmt, ##arg)

#define i82975x_mc_printk(mci, level, fmt, arg...) \
        edac_mc_chipset_printk(mci, level, "i82975x", fmt, ##arg)

#ifndef PCI_DEVICE_ID_INTEL_82975_0
#define PCI_DEVICE_ID_INTEL_82975_0     0x277c
#endif                          /* PCI_DEVICE_ID_INTEL_82975_0 */

#define I82975X_NR_CSROWS(nr_chans)             (8/(nr_chans))

/* Intel 82975X register addresses - device 0 function 0 - DRAM Controller */
#define I82975X_EAP             0x58    /* Dram Error Address Pointer (32b)
                                         *
                                         * 31:7  128 byte cache-line address
                                         * 6:1   reserved
                                         * 0     0: CH0; 1: CH1
                                         */

#define I82975X_DERRSYN         0x5c    /* Dram Error SYNdrome (8b)
                                         *
                                         *  7:0  DRAM ECC Syndrome
                                         */

#define I82975X_DES             0x5d    /* Dram ERRor DeSTination (8b)
                                         * 0h:    Processor Memory Reads
                                         * 1h:7h  reserved
                                         * More - See Page 65 of Intel DocSheet.
                                         */

#define I82975X_ERRSTS          0xc8    /* Error Status Register (16b)
                                         *
                                         * 15:12 reserved
                                         * 11    Thermal Sensor Event
                                         * 10    reserved
                                         *  9    non-DRAM lock error (ndlock)
                                         *  8    Refresh Timeout
                                         *  7:2  reserved
                                         *  1    ECC UE (multibit DRAM error)
                                         *  0    ECC CE (singlebit DRAM error)
                                         */

/* Error Reporting is supported by 3 mechanisms:
  1. DMI SERR generation  ( ERRCMD )
  2. SMI DMI  generation  ( SMICMD )
  3. SCI DMI  generation  ( SCICMD )
NOTE: Only ONE of the three must be enabled
*/
#define I82975X_ERRCMD          0xca    /* Error Command (16b)
                                         *
                                         * 15:12 reserved
                                         * 11    Thermal Sensor Event
                                         * 10    reserved
                                         *  9    non-DRAM lock error (ndlock)
                                         *  8    Refresh Timeout
                                         *  7:2  reserved
                                         *  1    ECC UE (multibit DRAM error)
                                         *  0    ECC CE (singlebit DRAM error)
                                         */

#define I82975X_SMICMD          0xcc    /* Error Command (16b)
                                         *
                                         * 15:2  reserved
                                         *  1    ECC UE (multibit DRAM error)
                                         *  0    ECC CE (singlebit DRAM error)
                                         */

#define I82975X_SCICMD          0xce    /* Error Command (16b)
                                         *
                                         * 15:2  reserved
                                         *  1    ECC UE (multibit DRAM error)
                                         *  0    ECC CE (singlebit DRAM error)
                                         */

#define I82975X_XEAP    0xfc    /* Extended Dram Error Address Pointer (8b)
                                         *
                                         * 7:1   reserved
                                         * 0     Bit32 of the Dram Error Address
                                         */

#define I82975X_MCHBAR          0x44    /*
                                         *
                                         * 31:14 Base Addr of 16K memory-mapped
                                         *      configuration space
                                         * 13:1  reserverd
                                         *  0    mem-mapped config space enable
                                         */

/* NOTE: Following addresses have to indexed using MCHBAR offset (44h, 32b) */
/* Intel 82975x memory mapped register space */

#define I82975X_DRB_SHIFT 25    /* fixed 32MiB grain */

#define I82975X_DRB             0x100   /* DRAM Row Boundary (8b x 8)
                                         *
                                         * 7   set to 1 in highest DRB of
                                         *      channel if 4GB in ch.
                                         * 6:2 upper boundary of rank in
                                         *      32MB grains
                                         * 1:0 set to 0
                                         */
#define I82975X_DRB_CH0R0               0x100
#define I82975X_DRB_CH0R1               0x101
#define I82975X_DRB_CH0R2               0x102
#define I82975X_DRB_CH0R3               0x103
#define I82975X_DRB_CH1R0               0x180
#define I82975X_DRB_CH1R1               0x181
#define I82975X_DRB_CH1R2               0x182
#define I82975X_DRB_CH1R3               0x183


#define I82975X_DRA             0x108   /* DRAM Row Attribute (4b x 8)
                                         *  defines the PAGE SIZE to be used
                                         *      for the rank
                                         *  7    reserved
                                         *  6:4  row attr of odd rank, i.e. 1
                                         *  3    reserved
                                         *  2:0  row attr of even rank, i.e. 0
                                         *
                                         * 000 = unpopulated
                                         * 001 = reserved
                                         * 010 = 4KiB
                                         * 011 = 8KiB
                                         * 100 = 16KiB
                                         * others = reserved
                                         */
#define I82975X_DRA_CH0R01              0x108
#define I82975X_DRA_CH0R23              0x109
#define I82975X_DRA_CH1R01              0x188
#define I82975X_DRA_CH1R23              0x189


#define I82975X_BNKARC  0x10e /* Type of device in each rank - Bank Arch (16b)
                                         *
                                         * 15:8  reserved
                                         * 7:6  Rank 3 architecture
                                         * 5:4  Rank 2 architecture
                                         * 3:2  Rank 1 architecture
                                         * 1:0  Rank 0 architecture
                                         *
                                         * 00 => x16 devices; i.e 4 banks
                                         * 01 => x8  devices; i.e 8 banks
                                         */
#define I82975X_C0BNKARC        0x10e
#define I82975X_C1BNKARC        0x18e



#define I82975X_DRC             0x120 /* DRAM Controller Mode0 (32b)
                                         *
                                         * 31:30 reserved
                                         * 29    init complete
                                         * 28:11 reserved, according to Intel
                                         *    22:21 number of channels
                                         *              00=1 01=2 in 82875
                                         *              seems to be ECC mode
                                         *              bits in 82975 in Asus
                                         *              P5W
                                         *       19:18 Data Integ Mode
                                         *              00=none 01=ECC in 82875
                                         * 10:8  refresh mode
                                         *  7    reserved
                                         *  6:4  mode select
                                         *  3:2  reserved
                                         *  1:0  DRAM type 10=Second Revision
                                         *              DDR2 SDRAM
                                         *         00, 01, 11 reserved
                                         */
#define I82975X_DRC_CH0M0               0x120
#define I82975X_DRC_CH1M0               0x1A0


#define I82975X_DRC_M1  0x124 /* DRAM Controller Mode1 (32b)
                                         * 31   0=Standard Address Map
                                         *      1=Enhanced Address Map
                                         * 30:0 reserved
                                         */

#define I82975X_DRC_CH0M1               0x124
#define I82975X_DRC_CH1M1               0x1A4

enum i82975x_chips {
        I82975X = 0,
};

struct i82975x_pvt {
        void __iomem *mch_window;
};

struct i82975x_dev_info {
        const char *ctl_name;
};

struct i82975x_error_info {
        u16 errsts;
        u32 eap;
        u8 des;
        u8 derrsyn;
        u16 errsts2;
        u8 chan;                /* the channel is bit 0 of EAP */
        u8 xeap;                /* extended eap bit */
};

static const struct i82975x_dev_info i82975x_devs[] = {
        [I82975X] = {
                .ctl_name = "i82975x"
        },
};

static struct pci_dev *mci_pdev;        /* init dev: in case that AGP code has
                                         * already registered driver
                                         */

static int i82975x_registered = 1;

static void i82975x_get_error_info(struct mem_ctl_info *mci,
                struct i82975x_error_info *info)
{
        struct pci_dev *pdev;

        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, I82975X_ERRSTS, &info->errsts);
        pci_read_config_dword(pdev, I82975X_EAP, &info->eap);
        pci_read_config_byte(pdev, I82975X_XEAP, &info->xeap);
        pci_read_config_byte(pdev, I82975X_DES, &info->des);
        pci_read_config_byte(pdev, I82975X_DERRSYN, &info->derrsyn);
        pci_read_config_word(pdev, I82975X_ERRSTS, &info->errsts2);

        pci_write_bits16(pdev, I82975X_ERRSTS, 0x0003, 0x0003);

        /*
         * If the error is the same then we can for both reads then
         * the first set of reads is valid.  If there is a change then
         * there is a CE no info and the second set of reads is valid
         * and should be UE info.
         */
        if (!(info->errsts2 & 0x0003))
                return;

        if ((info->errsts ^ info->errsts2) & 0x0003) {
                pci_read_config_dword(pdev, I82975X_EAP, &info->eap);
                pci_read_config_byte(pdev, I82975X_XEAP, &info->xeap);
                pci_read_config_byte(pdev, I82975X_DES, &info->des);
                pci_read_config_byte(pdev, I82975X_DERRSYN,
                                &info->derrsyn);
        }
}

static int i82975x_process_error_info(struct mem_ctl_info *mci,
                struct i82975x_error_info *info, int handle_errors)
{
        int row, multi_chan, chan;

        multi_chan = mci->csrows[0].nr_channels - 1;

        if (!(info->errsts2 & 0x0003))
                return 0;

        if (!handle_errors)
                return 1;

        if ((info->errsts ^ info->errsts2) & 0x0003) {
                edac_mc_handle_ce_no_info(mci, "UE overwrote CE");
                info->errsts = info->errsts2;
        }

        chan = info->eap & 1;
        info->eap >>= 1;
        if (info->xeap )
                info->eap |= 0x80000000;
        info->eap >>= PAGE_SHIFT;
        row = edac_mc_find_csrow_by_page(mci, info->eap);

        if (info->errsts & 0x0002)
                edac_mc_handle_ue(mci, info->eap, 0, row, "i82975x UE");
        else
                edac_mc_handle_ce(mci, info->eap, 0, info->derrsyn, row,
                                multi_chan ? chan : 0,
                                "i82975x CE");

        return 1;
}

static void i82975x_check(struct mem_ctl_info *mci)
{
        struct i82975x_error_info info;

        debugf1("MC%d: %s()\n", mci->mc_idx, __func__);
        i82975x_get_error_info(mci, &info);
        i82975x_process_error_info(mci, &info, 1);
}

/* Return 1 if dual channel mode is active.  Else return 0. */
static int dual_channel_active(void __iomem *mch_window)
{
        /*
         * We treat interleaved-symmetric configuration as dual-channel - EAP's
         * bit-0 giving the channel of the error location.
         *
         * All other configurations are treated as single channel - the EAP's
         * bit-0 will resolve ok in symmetric area of mixed
         * (symmetric/asymmetric) configurations
         */
        u8      drb[4][2];
        int     row;
        int    dualch;

        for (dualch = 1, row = 0; dualch && (row < 4); row++) {
                drb[row][0] = readb(mch_window + I82975X_DRB + row);
                drb[row][1] = readb(mch_window + I82975X_DRB + row + 0x80);
                dualch = dualch && (drb[row][0] == drb[row][1]);
        }
        return dualch;
}

static enum dev_type i82975x_dram_type(void __iomem *mch_window, int rank)
{
        /*
         * ASUS P5W DH either does not program this register or programs
         * it wrong!
         * ECC is possible on i92975x ONLY with DEV_X8 which should mean 'val'
         * for each rank should be 01b - the LSB of the word should be 0x55;
         * but it reads 0!
         */
        return DEV_X8;
}

static void i82975x_init_csrows(struct mem_ctl_info *mci,
                struct pci_dev *pdev, void __iomem *mch_window)
{
        struct csrow_info *csrow;
        unsigned long last_cumul_size;
        u8 value;
        u32 cumul_size;
        int index;

        last_cumul_size = 0;

        /*
         * 82875 comment:
         * The dram row boundary (DRB) reg values are boundary address
         * for each DRAM row with a granularity of 32 or 64MB (single/dual
         * channel operation).  DRB regs are cumulative; therefore DRB7 will
         * contain the total memory contained in all eight rows.
         *
         * FIXME:
         *  EDAC currently works for Dual-channel Interleaved configuration.
         *  Other configurations, which the chip supports, need fixing/testing.
         *
         */

        for (index = 0; index < mci->nr_csrows; index++) {
                csrow = &mci->csrows[index];

                value = readb(mch_window + I82975X_DRB + index +
                                        ((index >= 4) ? 0x80 : 0));
                cumul_size = value;
                cumul_size <<= (I82975X_DRB_SHIFT - PAGE_SHIFT);
                debugf3("%s(): (%d) cumul_size 0x%x\n", __func__, index,
                        cumul_size);
                if (cumul_size == last_cumul_size)
                        continue;       /* not populated */

                csrow->first_page = last_cumul_size;
                csrow->last_page = cumul_size - 1;
                csrow->nr_pages = cumul_size - last_cumul_size;
                last_cumul_size = cumul_size;
                csrow->grain = 1 << 7;  /* I82975X_EAP has 128B resolution */
                csrow->mtype = MEM_DDR; /* i82975x supports only DDR2 */
                csrow->dtype = i82975x_dram_type(mch_window, index);
                csrow->edac_mode = EDAC_SECDED; /* only supported */
        }
}

/* #define  i82975x_DEBUG_IOMEM */

#ifdef i82975x_DEBUG_IOMEM
static void i82975x_print_dram_timings(void __iomem *mch_window)
{
        /*
         * The register meanings are from Intel specs;
         * (shows 13-5-5-5 for 800-DDR2)
         * Asus P5W Bios reports 15-5-4-4
         * What's your religion?
         */
        static const int caslats[4] = { 5, 4, 3, 6 };
        u32     dtreg[2];

        dtreg[0] = readl(mch_window + 0x114);
        dtreg[1] = readl(mch_window + 0x194);
        i82975x_printk(KERN_INFO, "DRAM Timings :     Ch0    Ch1\n"
                "                RAS Active Min = %d     %d\n"
                "                CAS latency    =  %d      %d\n"
                "                RAS to CAS     =  %d      %d\n"
                "                RAS precharge  =  %d      %d\n",
                (dtreg[0] >> 19 ) & 0x0f,
                        (dtreg[1] >> 19) & 0x0f,
                caslats[(dtreg[0] >> 8) & 0x03],
                        caslats[(dtreg[1] >> 8) & 0x03],
                ((dtreg[0] >> 4) & 0x07) + 2,
                        ((dtreg[1] >> 4) & 0x07) + 2,
                (dtreg[0] & 0x07) + 2,
                        (dtreg[1] & 0x07) + 2
        );

}
#endif

static int i82975x_probe1(struct pci_dev *pdev, int dev_idx)
{
        int rc = -ENODEV;
        struct mem_ctl_info *mci;
        struct i82975x_pvt *pvt;
        void __iomem *mch_window;
        u32 mchbar;
        u32 drc[2];
        struct i82975x_error_info discard;
        int     chans;
#ifdef i82975x_DEBUG_IOMEM
        u8 c0drb[4];
        u8 c1drb[4];
#endif

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

        pci_read_config_dword(pdev, I82975X_MCHBAR, &mchbar);
        if (!(mchbar & 1)) {
                debugf3("%s(): failed, MCHBAR disabled!\n", __func__);
                goto fail0;
        }
        mchbar &= 0xffffc000;   /* bits 31:14 used for 16K window */
        mch_window = ioremap_nocache(mchbar, 0x1000);

#ifdef i82975x_DEBUG_IOMEM
        i82975x_printk(KERN_INFO, "MCHBAR real = %0x, remapped = %p\n",
                                        mchbar, mch_window);

        c0drb[0] = readb(mch_window + I82975X_DRB_CH0R0);
        c0drb[1] = readb(mch_window + I82975X_DRB_CH0R1);
        c0drb[2] = readb(mch_window + I82975X_DRB_CH0R2);
        c0drb[3] = readb(mch_window + I82975X_DRB_CH0R3);
        c1drb[0] = readb(mch_window + I82975X_DRB_CH1R0);
        c1drb[1] = readb(mch_window + I82975X_DRB_CH1R1);
        c1drb[2] = readb(mch_window + I82975X_DRB_CH1R2);
        c1drb[3] = readb(mch_window + I82975X_DRB_CH1R3);
        i82975x_printk(KERN_INFO, "DRBCH0R0 = 0x%02x\n", c0drb[0]);
        i82975x_printk(KERN_INFO, "DRBCH0R1 = 0x%02x\n", c0drb[1]);
        i82975x_printk(KERN_INFO, "DRBCH0R2 = 0x%02x\n", c0drb[2]);
        i82975x_printk(KERN_INFO, "DRBCH0R3 = 0x%02x\n", c0drb[3]);
        i82975x_printk(KERN_INFO, "DRBCH1R0 = 0x%02x\n", c1drb[0]);
        i82975x_printk(KERN_INFO, "DRBCH1R1 = 0x%02x\n", c1drb[1]);
        i82975x_printk(KERN_INFO, "DRBCH1R2 = 0x%02x\n", c1drb[2]);
        i82975x_printk(KERN_INFO, "DRBCH1R3 = 0x%02x\n", c1drb[3]);
#endif

        drc[0] = readl(mch_window + I82975X_DRC_CH0M0);
        drc[1] = readl(mch_window + I82975X_DRC_CH1M0);
#ifdef i82975x_DEBUG_IOMEM
        i82975x_printk(KERN_INFO, "DRC_CH0 = %0x, %s\n", drc[0],
                        ((drc[0] >> 21) & 3) == 1 ?
                                "ECC enabled" : "ECC disabled");
        i82975x_printk(KERN_INFO, "DRC_CH1 = %0x, %s\n", drc[1],
                        ((drc[1] >> 21) & 3) == 1 ?
                                "ECC enabled" : "ECC disabled");

        i82975x_printk(KERN_INFO, "C0 BNKARC = %0x\n",
                readw(mch_window + I82975X_C0BNKARC));
        i82975x_printk(KERN_INFO, "C1 BNKARC = %0x\n",
                readw(mch_window + I82975X_C1BNKARC));
        i82975x_print_dram_timings(mch_window);
        goto fail1;
#endif
        if (!(((drc[0] >> 21) & 3) == 1 || ((drc[1] >> 21) & 3) == 1)) {
                i82975x_printk(KERN_INFO, "ECC disabled on both channels.\n");
                goto fail1;
        }

        chans = dual_channel_active(mch_window) + 1;

        /* assuming only one controller, index thus is 0 */
        mci = edac_mc_alloc(sizeof(*pvt), I82975X_NR_CSROWS(chans),
                                        chans, 0);
        if (!mci) {
                rc = -ENOMEM;
                goto fail1;
        }

        debugf3("%s(): init mci\n", __func__);
        mci->dev = &pdev->dev;
        mci->mtype_cap = MEM_FLAG_DDR;
        mci->edac_ctl_cap = EDAC_FLAG_NONE | EDAC_FLAG_SECDED;
        mci->edac_cap = EDAC_FLAG_NONE | EDAC_FLAG_SECDED;
        mci->mod_name = EDAC_MOD_STR;
        mci->mod_ver = I82975X_REVISION;
        mci->ctl_name = i82975x_devs[dev_idx].ctl_name;
        mci->edac_check = i82975x_check;
        mci->ctl_page_to_phys = NULL;
        debugf3("%s(): init pvt\n", __func__);
        pvt = (struct i82975x_pvt *) mci->pvt_info;
        pvt->mch_window = mch_window;
        i82975x_init_csrows(mci, pdev, mch_window);
        i82975x_get_error_info(mci, &discard);  /* clear counters */

        /* finalize this instance of memory controller with edac core */
        if (edac_mc_add_mc(mci)) {
                debugf3("%s(): failed edac_mc_add_mc()\n", __func__);
                goto fail2;
        }

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

fail2:
        edac_mc_free(mci);

fail1:
        iounmap(mch_window);
fail0:
        return rc;
}

/* returns count (>= 0), or negative on error */
static int __devinit i82975x_init_one(struct pci_dev *pdev,
                const struct pci_device_id *ent)
{
        int rc;

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

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

        rc = i82975x_probe1(pdev, ent->driver_data);

        if (mci_pdev == NULL)
                mci_pdev = pci_dev_get(pdev);

        return rc;
}

static void __devexit i82975x_remove_one(struct pci_dev *pdev)
{
        struct mem_ctl_info *mci;
        struct i82975x_pvt *pvt;

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

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

        pvt = mci->pvt_info;
        if (pvt->mch_window)
                iounmap( pvt->mch_window );

        edac_mc_free(mci);
}

static const struct pci_device_id i82975x_pci_tbl[] __devinitdata = {
        {
                PCI_VEND_DEV(INTEL, 82975_0), PCI_ANY_ID, PCI_ANY_ID, 0, 0,
                I82975X
        },
        {
                0,
        }       /* 0 terminated list. */
};

MODULE_DEVICE_TABLE(pci, i82975x_pci_tbl);

static struct pci_driver i82975x_driver = {
        .name = EDAC_MOD_STR,
        .probe = i82975x_init_one,
        .remove = __devexit_p(i82975x_remove_one),
        .id_table = i82975x_pci_tbl,
};

static int __init i82975x_init(void)
{
        int pci_rc;

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

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

        pci_rc = pci_register_driver(&i82975x_driver);
        if (pci_rc < 0)
                goto fail0;

        if (mci_pdev == NULL) {
                mci_pdev = pci_get_device(PCI_VENDOR_ID_INTEL,
                                PCI_DEVICE_ID_INTEL_82975_0, NULL);

                if (!mci_pdev) {
                        debugf0("i82975x pci_get_device fail\n");
                        pci_rc = -ENODEV;
                        goto fail1;
                }

                pci_rc = i82975x_init_one(mci_pdev, i82975x_pci_tbl);

                if (pci_rc < 0) {
                        debugf0("i82975x init fail\n");
                        pci_rc = -ENODEV;
                        goto fail1;
                }
        }

        return 0;

fail1:
        pci_unregister_driver(&i82975x_driver);

fail0:
        if (mci_pdev != NULL)
                pci_dev_put(mci_pdev);

        return pci_rc;
}

static void __exit i82975x_exit(void)
{
        debugf3("%s()\n", __func__);

        pci_unregister_driver(&i82975x_driver);

        if (!i82975x_registered) {
                i82975x_remove_one(mci_pdev);
                pci_dev_put(mci_pdev);
        }
}

module_init(i82975x_init);
module_exit(i82975x_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arvind R. <arvind@acarlab.com>");
MODULE_DESCRIPTION("MC support for Intel 82975 memory hub controllers");

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