/*
 * Intel 82443BX/GX (440BX/GX chipset) Memory Controller EDAC kernel
 * module (C) 2006 Tim Small
 *
 * This file may be distributed under the terms of the GNU General
 * Public License.
 *
 * Written by Tim Small <tim@buttersideup.com>, based on work by Linux
 * Networx, Thayne Harbaugh, Dan Hollis <goemon at anime dot net> and
 * others.
 *
 * 440GX fix by Jason Uhlenkott <juhlenko@akamai.com>.
 *
 * Written with reference to 82443BX Host Bridge Datasheet:
 * http://download.intel.com/design/chipsets/datashts/29063301.pdf
 * references to this document given in [].
 *
 * This module doesn't support the 440LX, but it may be possible to
 * make it do so (the 440LX's register definitions are different, but
 * not completely so - I haven't studied them in enough detail to know
 * how easy this would be).
 */

#include <linux/module.h>
#include <linux/init.h>

#include <linux/pci.h>
#include <linux/pci_ids.h>


#include <linux/edac.h>
#include "edac_core.h"

#define I82443_REVISION "0.1"

#define EDAC_MOD_STR    "i82443bxgx_edac"

/* The 82443BX supports SDRAM, or EDO (EDO for mobile only), "Memory
 * Size: 8 MB to 512 MB (1GB with Registered DIMMs) with eight memory
 * rows" "The 82443BX supports multiple-bit error detection and
 * single-bit error correction when ECC mode is enabled and
 * single/multi-bit error detection when correction is disabled.
 * During writes to the DRAM, the 82443BX generates ECC for the data
 * on a QWord basis. Partial QWord writes require a read-modify-write
 * cycle when ECC is enabled."
*/

/* "Additionally, the 82443BX ensures that the data is corrected in
 * main memory so that accumulation of errors is prevented. Another
 * error within the same QWord would result in a double-bit error
 * which is unrecoverable. This is known as hardware scrubbing since
 * it requires no software intervention to correct the data in memory."
 */

/* [Also see page 100 (section 4.3), "DRAM Interface"]
 * [Also see page 112 (section 4.6.1.4), ECC]
 */

#define I82443BXGX_NR_CSROWS 8
#define I82443BXGX_NR_CHANS  1
#define I82443BXGX_NR_DIMMS  4

/* 82443 PCI Device 0 */
#define I82443BXGX_NBXCFG 0x50  /* 32bit register starting at this PCI
                                 * config space offset */
#define I82443BXGX_NBXCFG_OFFSET_NON_ECCROW 24  /* Array of bits, zero if
                                                 * row is non-ECC */
#define I82443BXGX_NBXCFG_OFFSET_DRAM_FREQ 12   /* 2 bits,00=100MHz,10=66 MHz */

#define I82443BXGX_NBXCFG_OFFSET_DRAM_INTEGRITY 7       /* 2 bits:       */
#define I82443BXGX_NBXCFG_INTEGRITY_NONE   0x0  /* 00 = Non-ECC */
#define I82443BXGX_NBXCFG_INTEGRITY_EC     0x1  /* 01 = EC (only) */
#define I82443BXGX_NBXCFG_INTEGRITY_ECC    0x2  /* 10 = ECC */
#define I82443BXGX_NBXCFG_INTEGRITY_SCRUB  0x3  /* 11 = ECC + HW Scrub */

#define I82443BXGX_NBXCFG_OFFSET_ECC_DIAG_ENABLE  6

/* 82443 PCI Device 0 */
#define I82443BXGX_EAP   0x80   /* 32bit register starting at this PCI
                                 * config space offset, Error Address
                                 * Pointer Register */
#define I82443BXGX_EAP_OFFSET_EAP  12   /* High 20 bits of error address */
#define I82443BXGX_EAP_OFFSET_MBE  BIT(1)       /* Err at EAP was multi-bit (W1TC) */
#define I82443BXGX_EAP_OFFSET_SBE  BIT(0)       /* Err at EAP was single-bit (W1TC) */

#define I82443BXGX_ERRCMD  0x90 /* 8bit register starting at this PCI
                                 * config space offset. */
#define I82443BXGX_ERRCMD_OFFSET_SERR_ON_MBE BIT(1)     /* 1 = enable */
#define I82443BXGX_ERRCMD_OFFSET_SERR_ON_SBE BIT(0)     /* 1 = enable */

#define I82443BXGX_ERRSTS  0x91 /* 16bit register starting at this PCI
                                 * config space offset. */
#define I82443BXGX_ERRSTS_OFFSET_MBFRE 5        /* 3 bits - first err row multibit */
#define I82443BXGX_ERRSTS_OFFSET_MEF   BIT(4)   /* 1 = MBE occurred */
#define I82443BXGX_ERRSTS_OFFSET_SBFRE 1        /* 3 bits - first err row singlebit */
#define I82443BXGX_ERRSTS_OFFSET_SEF   BIT(0)   /* 1 = SBE occurred */

#define I82443BXGX_DRAMC 0x57   /* 8bit register starting at this PCI
                                 * config space offset. */
#define I82443BXGX_DRAMC_OFFSET_DT 3    /* 2 bits, DRAM Type */
#define I82443BXGX_DRAMC_DRAM_IS_EDO 0  /* 00 = EDO */
#define I82443BXGX_DRAMC_DRAM_IS_SDRAM 1        /* 01 = SDRAM */
#define I82443BXGX_DRAMC_DRAM_IS_RSDRAM 2       /* 10 = Registered SDRAM */

#define I82443BXGX_DRB 0x60     /* 8x 8bit registers starting at this PCI
                                 * config space offset. */

/* FIXME - don't poll when ECC disabled? */

struct i82443bxgx_edacmc_error_info {
        u32 eap;
};

static struct edac_pci_ctl_info *i82443bxgx_pci;

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

static int i82443bxgx_registered = 1;

static void i82443bxgx_edacmc_get_error_info(struct mem_ctl_info *mci,
                                struct i82443bxgx_edacmc_error_info
                                *info)
{
        struct pci_dev *pdev;
        pdev = to_pci_dev(mci->pdev);
        pci_read_config_dword(pdev, I82443BXGX_EAP, &info->eap);
        if (info->eap & I82443BXGX_EAP_OFFSET_SBE)
                /* Clear error to allow next error to be reported [p.61] */
                pci_write_bits32(pdev, I82443BXGX_EAP,
                                 I82443BXGX_EAP_OFFSET_SBE,
                                 I82443BXGX_EAP_OFFSET_SBE);

        if (info->eap & I82443BXGX_EAP_OFFSET_MBE)
                /* Clear error to allow next error to be reported [p.61] */
                pci_write_bits32(pdev, I82443BXGX_EAP,
                                 I82443BXGX_EAP_OFFSET_MBE,
                                 I82443BXGX_EAP_OFFSET_MBE);
}

static int i82443bxgx_edacmc_process_error_info(struct mem_ctl_info *mci,
                                                struct
                                                i82443bxgx_edacmc_error_info
                                                *info, int handle_errors)
{
        int error_found = 0;
        u32 eapaddr, page, pageoffset;

        /* bits 30:12 hold the 4kb block in which the error occurred
         * [p.61] */
        eapaddr = (info->eap & 0xfffff000);
        page = eapaddr >> PAGE_SHIFT;
        pageoffset = eapaddr - (page << PAGE_SHIFT);

        if (info->eap & I82443BXGX_EAP_OFFSET_SBE) {
                error_found = 1;
                if (handle_errors)
                        edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci, 1,
                                             page, pageoffset, 0,
                                             edac_mc_find_csrow_by_page(mci, page),
                                             0, -1, mci->ctl_name, "");
        }

        if (info->eap & I82443BXGX_EAP_OFFSET_MBE) {
                error_found = 1;
                if (handle_errors)
                        edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci, 1,
                                             page, pageoffset, 0,
                                             edac_mc_find_csrow_by_page(mci, page),
                                             0, -1, mci->ctl_name, "");
        }

        return error_found;
}

static void i82443bxgx_edacmc_check(struct mem_ctl_info *mci)
{
        struct i82443bxgx_edacmc_error_info info;

        edac_dbg(1, "MC%d\n", mci->mc_idx);
        i82443bxgx_edacmc_get_error_info(mci, &info);
        i82443bxgx_edacmc_process_error_info(mci, &info, 1);
}

static void i82443bxgx_init_csrows(struct mem_ctl_info *mci,
                                struct pci_dev *pdev,
                                enum edac_type edac_mode,
                                enum mem_type mtype)
{
        struct csrow_info *csrow;
        struct dimm_info *dimm;
        int index;
        u8 drbar, dramc;
        u32 row_base, row_high_limit, row_high_limit_last;

        pci_read_config_byte(pdev, I82443BXGX_DRAMC, &dramc);
        row_high_limit_last = 0;
        for (index = 0; index < mci->nr_csrows; index++) {
                csrow = mci->csrows[index];
                dimm = csrow->channels[0]->dimm;

                pci_read_config_byte(pdev, I82443BXGX_DRB + index, &drbar);
                edac_dbg(1, "MC%d: Row=%d DRB = %#0x\n",
                         mci->mc_idx, index, drbar);
                row_high_limit = ((u32) drbar << 23);
                /* find the DRAM Chip Select Base address and mask */
                edac_dbg(1, "MC%d: Row=%d, Boundary Address=%#0x, Last = %#0x\n",
                         mci->mc_idx, index, row_high_limit,
                         row_high_limit_last);

                /* 440GX goes to 2GB, represented with a DRB of 0. */
                if (row_high_limit_last && !row_high_limit)
                        row_high_limit = 1UL << 31;

                /* This row is empty [p.49] */
                if (row_high_limit == row_high_limit_last)
                        continue;
                row_base = row_high_limit_last;
                csrow->first_page = row_base >> PAGE_SHIFT;
                csrow->last_page = (row_high_limit >> PAGE_SHIFT) - 1;
                dimm->nr_pages = csrow->last_page - csrow->first_page + 1;
                /* EAP reports in 4kilobyte granularity [61] */
                dimm->grain = 1 << 12;
                dimm->mtype = mtype;
                /* I don't think 440BX can tell you device type? FIXME? */
                dimm->dtype = DEV_UNKNOWN;
                /* Mode is global to all rows on 440BX */
                dimm->edac_mode = edac_mode;
                row_high_limit_last = row_high_limit;
        }
}

static int i82443bxgx_edacmc_probe1(struct pci_dev *pdev, int dev_idx)
{
        struct mem_ctl_info *mci;
        struct edac_mc_layer layers[2];
        u8 dramc;
        u32 nbxcfg, ecc_mode;
        enum mem_type mtype;
        enum edac_type edac_mode;

        edac_dbg(0, "MC:\n");

        /* Something is really hosed if PCI config space reads from
         * the MC aren't working.
         */
        if (pci_read_config_dword(pdev, I82443BXGX_NBXCFG, &nbxcfg))
                return -EIO;

        layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
        layers[0].size = I82443BXGX_NR_CSROWS;
        layers[0].is_virt_csrow = true;
        layers[1].type = EDAC_MC_LAYER_CHANNEL;
        layers[1].size = I82443BXGX_NR_CHANS;
        layers[1].is_virt_csrow = false;
        mci = edac_mc_alloc(0, ARRAY_SIZE(layers), layers, 0);
        if (mci == NULL)
                return -ENOMEM;

        edac_dbg(0, "MC: mci = %p\n", mci);
        mci->pdev = &pdev->dev;
        mci->mtype_cap = MEM_FLAG_EDO | MEM_FLAG_SDR | MEM_FLAG_RDR;
        mci->edac_ctl_cap = EDAC_FLAG_NONE | EDAC_FLAG_EC | EDAC_FLAG_SECDED;
        pci_read_config_byte(pdev, I82443BXGX_DRAMC, &dramc);
        switch ((dramc >> I82443BXGX_DRAMC_OFFSET_DT) & (BIT(0) | BIT(1))) {
        case I82443BXGX_DRAMC_DRAM_IS_EDO:
                mtype = MEM_EDO;
                break;
        case I82443BXGX_DRAMC_DRAM_IS_SDRAM:
                mtype = MEM_SDR;
                break;
        case I82443BXGX_DRAMC_DRAM_IS_RSDRAM:
                mtype = MEM_RDR;
                break;
        default:
                edac_dbg(0, "Unknown/reserved DRAM type value in DRAMC register!\n");
                mtype = -MEM_UNKNOWN;
        }

        if ((mtype == MEM_SDR) || (mtype == MEM_RDR))
                mci->edac_cap = mci->edac_ctl_cap;
        else
                mci->edac_cap = EDAC_FLAG_NONE;

        mci->scrub_cap = SCRUB_FLAG_HW_SRC;
        pci_read_config_dword(pdev, I82443BXGX_NBXCFG, &nbxcfg);
        ecc_mode = ((nbxcfg >> I82443BXGX_NBXCFG_OFFSET_DRAM_INTEGRITY) &
                (BIT(0) | BIT(1)));

        mci->scrub_mode = (ecc_mode == I82443BXGX_NBXCFG_INTEGRITY_SCRUB)
                ? SCRUB_HW_SRC : SCRUB_NONE;

        switch (ecc_mode) {
        case I82443BXGX_NBXCFG_INTEGRITY_NONE:
                edac_mode = EDAC_NONE;
                break;
        case I82443BXGX_NBXCFG_INTEGRITY_EC:
                edac_mode = EDAC_EC;
                break;
        case I82443BXGX_NBXCFG_INTEGRITY_ECC:
        case I82443BXGX_NBXCFG_INTEGRITY_SCRUB:
                edac_mode = EDAC_SECDED;
                break;
        default:
                edac_dbg(0, "Unknown/reserved ECC state in NBXCFG register!\n");
                edac_mode = EDAC_UNKNOWN;
                break;
        }

        i82443bxgx_init_csrows(mci, pdev, edac_mode, mtype);

        /* Many BIOSes don't clear error flags on boot, so do this
         * here, or we get "phantom" errors occurring at module-load
         * time. */
        pci_write_bits32(pdev, I82443BXGX_EAP,
                        (I82443BXGX_EAP_OFFSET_SBE |
                                I82443BXGX_EAP_OFFSET_MBE),
                        (I82443BXGX_EAP_OFFSET_SBE |
                                I82443BXGX_EAP_OFFSET_MBE));

        mci->mod_name = EDAC_MOD_STR;
        mci->mod_ver = I82443_REVISION;
        mci->ctl_name = "I82443BXGX";
        mci->dev_name = pci_name(pdev);
        mci->edac_check = i82443bxgx_edacmc_check;
        mci->ctl_page_to_phys = NULL;

        if (edac_mc_add_mc(mci)) {
                edac_dbg(3, "failed edac_mc_add_mc()\n");
                goto fail;
        }

        /* allocating generic PCI control info */
        i82443bxgx_pci = edac_pci_create_generic_ctl(&pdev->dev, EDAC_MOD_STR);
        if (!i82443bxgx_pci) {
                printk(KERN_WARNING
                        "%s(): Unable to create PCI control\n",
                        __func__);
                printk(KERN_WARNING
                        "%s(): PCI error report via EDAC not setup\n",
                        __func__);
        }

        edac_dbg(3, "MC: success\n");
        return 0;

fail:
        edac_mc_free(mci);
        return -ENODEV;
}

EXPORT_SYMBOL_GPL(i82443bxgx_edacmc_probe1);

/* returns count (>= 0), or negative on error */
static int i82443bxgx_edacmc_init_one(struct pci_dev *pdev,
                                      const struct pci_device_id *ent)
{
        int rc;

        edac_dbg(0, "MC:\n");

        /* don't need to call pci_enable_device() */
        rc = i82443bxgx_edacmc_probe1(pdev, ent->driver_data);

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

        return rc;
}

static void i82443bxgx_edacmc_remove_one(struct pci_dev *pdev)
{
        struct mem_ctl_info *mci;

        edac_dbg(0, "\n");

        if (i82443bxgx_pci)
                edac_pci_release_generic_ctl(i82443bxgx_pci);

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

        edac_mc_free(mci);
}

EXPORT_SYMBOL_GPL(i82443bxgx_edacmc_remove_one);

static const struct pci_device_id i82443bxgx_pci_tbl[] = {
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443BX_0)},
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443BX_2)},
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443GX_0)},
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443GX_2)},
        {0,}                    /* 0 terminated list. */
};

MODULE_DEVICE_TABLE(pci, i82443bxgx_pci_tbl);

static struct pci_driver i82443bxgx_edacmc_driver = {
        .name = EDAC_MOD_STR,
        .probe = i82443bxgx_edacmc_init_one,
        .remove = i82443bxgx_edacmc_remove_one,
        .id_table = i82443bxgx_pci_tbl,
};

static int __init i82443bxgx_edacmc_init(void)
{
        int pci_rc;
       /* Ensure that the OPSTATE is set correctly for POLL or NMI */
       opstate_init();

        pci_rc = pci_register_driver(&i82443bxgx_edacmc_driver);
        if (pci_rc < 0)
                goto fail0;

        if (mci_pdev == NULL) {
                const struct pci_device_id *id = &i82443bxgx_pci_tbl[0];
                int i = 0;
                i82443bxgx_registered = 0;

                while (mci_pdev == NULL && id->vendor != 0) {
                        mci_pdev = pci_get_device(id->vendor,
                                        id->device, NULL);
                        i++;
                        id = &i82443bxgx_pci_tbl[i];
                }
                if (!mci_pdev) {
                        edac_dbg(0, "i82443bxgx pci_get_device fail\n");
                        pci_rc = -ENODEV;
                        goto fail1;
                }

                pci_rc = i82443bxgx_edacmc_init_one(mci_pdev, i82443bxgx_pci_tbl);

                if (pci_rc < 0) {
                        edac_dbg(0, "i82443bxgx init fail\n");
                        pci_rc = -ENODEV;
                        goto fail1;
                }
        }

        return 0;

fail1:
        pci_unregister_driver(&i82443bxgx_edacmc_driver);

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

        return pci_rc;
}

static void __exit i82443bxgx_edacmc_exit(void)
{
        pci_unregister_driver(&i82443bxgx_edacmc_driver);

        if (!i82443bxgx_registered)
                i82443bxgx_edacmc_remove_one(mci_pdev);

        pci_dev_put(mci_pdev);
}

module_init(i82443bxgx_edacmc_init);
module_exit(i82443bxgx_edacmc_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tim Small <tim@buttersideup.com> - WPAD");
MODULE_DESCRIPTION("EDAC MC support for Intel 82443BX/GX memory controllers");

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