/*
   * 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->dev);
  	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_ce(mci, page, pageoffset,

  				/* 440BX/GX don't make syndrome information
  				 * available */
  				0, edac_mc_find_csrow_by_page(mci, page), 0,
  				mci->ctl_name);

  	}

  	if (info->eap & I82443BXGX_EAP_OFFSET_MBE) {

  		error_found = 1;
  		if (handle_errors)

  			edac_mc_handle_ue(mci, page, pageoffset,

  					edac_mc_find_csrow_by_page(mci, page),
  					mci->ctl_name);

  	}
  
  	return error_found;
  }

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

  	debugf1("MC%d: %s: %s()
  ", mci->mc_idx, __FILE__, __func__);

  	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;
  	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];
  		pci_read_config_byte(pdev, I82443BXGX_DRB + index, &drbar);

  		debugf1("MC%d: %s: %s() Row=%d DRB = %#0x
  ",
  			mci->mc_idx, __FILE__, __func__, index, drbar);

  		row_high_limit = ((u32) drbar << 23);
  		/* find the DRAM Chip Select Base address and mask */

  		debugf1("MC%d: %s: %s() Row=%d, "

  			"Boundary Address=%#0x, Last = %#0x
  ",

  			mci->mc_idx, __FILE__, __func__, 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;
  		csrow->nr_pages = csrow->last_page - csrow->first_page + 1;
  		/* EAP reports in 4kilobyte granularity [61] */
  		csrow->grain = 1 << 12;
  		csrow->mtype = mtype;
  		/* I don't think 440BX can tell you device type? FIXME? */
  		csrow->dtype = DEV_UNKNOWN;
  		/* Mode is global to all rows on 440BX */
  		csrow->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;
  	u8 dramc;
  	u32 nbxcfg, ecc_mode;
  	enum mem_type mtype;
  	enum edac_type edac_mode;

  	debugf0("MC: %s: %s()
  ", __FILE__, __func__);

  
  	/* 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;

  	mci = edac_mc_alloc(0, I82443BXGX_NR_CSROWS, I82443BXGX_NR_CHANS, 0);

  
  	if (mci == NULL)
  		return -ENOMEM;

  	debugf0("MC: %s: %s(): mci = %p
  ", __FILE__, __func__, mci);

  	mci->dev = &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:

  		debugf0("Unknown/reserved DRAM type value "
  			"in DRAMC register!
  ");

  		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:

  		debugf0("%s(): Unknown/reserved ECC state "
  			"in NBXCFG register!
  ", __func__);

  		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)) {

  		debugf3("%s(): failed edac_mc_add_mc()
  ", __func__);
  		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
  ",
  			__func__);
  		printk(KERN_WARNING
  			"%s(): PCI error report via EDAC not setup
  ",
  			__func__);
  	}

  	debugf3("MC: %s: %s(): success
  ", __FILE__, __func__);

  	return 0;

  fail:

  	edac_mc_free(mci);
  	return -ENODEV;
  }

  EXPORT_SYMBOL_GPL(i82443bxgx_edacmc_probe1);
  
  /* returns count (>= 0), or negative on error */
  static int __devinit i82443bxgx_edacmc_init_one(struct pci_dev *pdev,

  						const struct pci_device_id *ent)

  {

  	int rc;

  	debugf0("MC: %s: %s()
  ", __FILE__, __func__);

  	/* 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 __devexit i82443bxgx_edacmc_remove_one(struct pci_dev *pdev)
  {
  	struct mem_ctl_info *mci;

  	debugf0("%s: %s()
  ", __FILE__, __func__);

  	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[] __devinitdata = {
  	{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 = __devexit_p(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) {
  			debugf0("i82443bxgx pci_get_device fail
  ");
  			pci_rc = -ENODEV;
  			goto fail1;
  		}
  
  		pci_rc = i82443bxgx_edacmc_init_one(mci_pdev, i82443bxgx_pci_tbl);
  
  		if (pci_rc < 0) {
  			debugf0("i82443bxgx init fail
  ");
  			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);
  
  	if (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");