/*
 * Radisys 82600 Embedded chipset Memory Controller kernel module
 * (C) 2005 EADS Astrium
 * 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 Thayne
 * Harbaugh, Dan Hollis <goemon at anime dot net> and others.
 *
 * $Id: edac_r82600.c,v 1.1.2.6 2005/10/05 00:43:44 dsp_llnl Exp $
 *
 * Written with reference to 82600 High Integration Dual PCI System
 * Controller Data Book:
 * http://www.radisys.com/files/support_downloads/007-01277-0002.82600DataBook.pdf
 * references to this document given in []
 */

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

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

#include <linux/slab.h>

#include "edac_mc.h"

/* Radisys say "The 82600 integrates a main memory SDRAM controller that
 * supports up to four banks of memory. The four banks can support a mix of
 * sizes of 64 bit wide (72 bits with ECC) Synchronous DRAM (SDRAM) DIMMs,
 * each of which can be any size from 16MB to 512MB. Both registered (control
 * signals buffered) and unbuffered DIMM types are supported. Mixing of
 * registered and unbuffered DIMMs as well as mixing of ECC and non-ECC DIMMs
 * is not allowed. The 82600 SDRAM interface operates at the same frequency as
 * the CPU bus, 66MHz, 100MHz or 133MHz."
 */

#define R82600_NR_CSROWS 4
#define R82600_NR_CHANS  1
#define R82600_NR_DIMMS  4

#define R82600_BRIDGE_ID  0x8200

/* Radisys 82600 register addresses - device 0 function 0 - PCI bridge */
#define R82600_DRAMC	0x57	/* Various SDRAM related control bits
				 * all bits are R/W
				 *
				 * 7    SDRAM ISA Hole Enable
				 * 6    Flash Page Mode Enable
				 * 5    ECC Enable: 1=ECC 0=noECC
				 * 4    DRAM DIMM Type: 1=
				 * 3    BIOS Alias Disable
				 * 2    SDRAM BIOS Flash Write Enable
				 * 1:0  SDRAM Refresh Rate: 00=Disabled
				 *          01=7.8usec (256Mbit SDRAMs)
				 *          10=15.6us 11=125usec
				 */

#define R82600_SDRAMC	0x76	/* "SDRAM Control Register"
				 * More SDRAM related control bits
				 * all bits are R/W
				 *
				 * 15:8 Reserved.
				 *
				 * 7:5  Special SDRAM Mode Select
				 *
				 * 4    Force ECC
				 *
				 *        1=Drive ECC bits to 0 during
				 *          write cycles (i.e. ECC test mode)
				 *
				 *        0=Normal ECC functioning
				 *
				 * 3    Enhanced Paging Enable
				 *
				 * 2    CAS# Latency 0=3clks 1=2clks
				 *
				 * 1    RAS# to CAS# Delay 0=3 1=2
				 *
				 * 0    RAS# Precharge     0=3 1=2
				 */

#define R82600_EAP	0x80	/* ECC Error Address Pointer Register
				 *
				 * 31    Disable Hardware Scrubbing (RW)
				 *        0=Scrub on corrected read
				 *        1=Don't scrub on corrected read
				 *
				 * 30:12 Error Address Pointer (RO)
				 *        Upper 19 bits of error address
				 *
				 * 11:4  Syndrome Bits (RO)
				 *
				 * 3     BSERR# on multibit error (RW)
				 *        1=enable 0=disable
				 *
				 * 2     NMI on Single Bit Eror (RW)
				 *        1=NMI triggered by SBE n.b. other
				 *          prerequeists
				 *        0=NMI not triggered
				 *
				 * 1     MBE (R/WC)
				 *        read 1=MBE at EAP (see above)
				 *        read 0=no MBE, or SBE occurred first
				 *        write 1=Clear MBE status (must also
				 *          clear SBE)
				 *        write 0=NOP
				 *
				 * 1     SBE (R/WC)
				 *        read 1=SBE at EAP (see above)
				 *        read 0=no SBE, or MBE occurred first
				 *        write 1=Clear SBE status (must also
				 *          clear MBE)
				 *        write 0=NOP
				 */

#define R82600_DRBA	0x60	/* + 0x60..0x63 SDRAM Row Boundry Address
				 *  Registers
				 *
				 * 7:0  Address lines 30:24 - upper limit of
				 * each row [p57]
				 */

struct r82600_error_info {
	u32 eapr;
};


static unsigned int disable_hardware_scrub = 0;


static void r82600_get_error_info (struct mem_ctl_info *mci,
		struct r82600_error_info *info)
{
	pci_read_config_dword(mci->pdev, R82600_EAP, &info->eapr);

	if (info->eapr & BIT(0))
		/* Clear error to allow next error to be reported [p.62] */
		pci_write_bits32(mci->pdev, R82600_EAP,
				   ((u32) BIT(0) & (u32) BIT(1)),
				   ((u32) BIT(0) & (u32) BIT(1)));

	if (info->eapr & BIT(1))
		/* Clear error to allow next error to be reported [p.62] */
		pci_write_bits32(mci->pdev, R82600_EAP,
				   ((u32) BIT(0) & (u32) BIT(1)),
				   ((u32) BIT(0) & (u32) BIT(1)));
}


static int r82600_process_error_info (struct mem_ctl_info *mci,
		struct r82600_error_info *info, int handle_errors)
{
	int error_found;
	u32 eapaddr, page;
	u32 syndrome;

	error_found = 0;

	/* bits 30:12 store the upper 19 bits of the 32 bit error address */
	eapaddr = ((info->eapr >> 12) & 0x7FFF) << 13;
	/* Syndrome in bits 11:4 [p.62]       */
	syndrome = (info->eapr >> 4) & 0xFF;

	/* the R82600 reports at less than page *
	 * granularity (upper 19 bits only)     */
	page = eapaddr >> PAGE_SHIFT;

	if (info->eapr & BIT(0)) { 	/* CE? */
		error_found = 1;

		if (handle_errors)
			edac_mc_handle_ce(
			    mci, page, 0,	/* not avail */
			    syndrome,
			    edac_mc_find_csrow_by_page(mci, page),
			    0,	/* channel */
			    mci->ctl_name);
	}

	if (info->eapr & BIT(1)) { 	/* UE? */
		error_found = 1;

		if (handle_errors)
			/* 82600 doesn't give enough info */
			edac_mc_handle_ue(mci, page, 0,
			    edac_mc_find_csrow_by_page(mci, page),
			    mci->ctl_name);
	}

	return error_found;
}

static void r82600_check(struct mem_ctl_info *mci)
{
	struct r82600_error_info info;

	debugf1("MC%d: " __FILE__ ": %s()\n", mci->mc_idx, __func__);
	r82600_get_error_info(mci, &info);
	r82600_process_error_info(mci, &info, 1);
}

static int r82600_probe1(struct pci_dev *pdev, int dev_idx)
{
	int rc = -ENODEV;
	int index;
	struct mem_ctl_info *mci = NULL;
	u8 dramcr;
	u32 ecc_on;
	u32 reg_sdram;
	u32 eapr;
	u32 scrub_disabled;
	u32 sdram_refresh_rate;
	u32 row_high_limit_last = 0;
	u32 eap_init_bits;

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


	pci_read_config_byte(pdev, R82600_DRAMC, &dramcr);
	pci_read_config_dword(pdev, R82600_EAP, &eapr);

	ecc_on = dramcr & BIT(5);
	reg_sdram = dramcr & BIT(4);
	scrub_disabled = eapr & BIT(31);
	sdram_refresh_rate = dramcr & (BIT(0) | BIT(1));

	debugf2("MC: " __FILE__ ": %s(): sdram refresh rate = %#0x\n",
		__func__, sdram_refresh_rate);

	debugf2("MC: " __FILE__ ": %s(): DRAMC register = %#0x\n", __func__,
		dramcr);

	mci = edac_mc_alloc(0, R82600_NR_CSROWS, R82600_NR_CHANS);

	if (mci == NULL) {
		rc = -ENOMEM;
		goto fail;
	}

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

	mci->pdev = pdev;
	mci->mtype_cap = MEM_FLAG_RDDR | MEM_FLAG_DDR;

	mci->edac_ctl_cap = EDAC_FLAG_NONE | EDAC_FLAG_EC | EDAC_FLAG_SECDED;
	/* FIXME try to work out if the chip leads have been                 *
	 * used for COM2 instead on this board? [MA6?]       MAYBE:          */

	/* On the R82600, the pins for memory bits 72:65 - i.e. the   *
	 * EC bits are shared with the pins for COM2 (!), so if COM2  *
	 * is enabled, we assume COM2 is wired up, and thus no EDAC   *
	 * is possible.                                               */
	mci->edac_cap = EDAC_FLAG_NONE | EDAC_FLAG_EC | EDAC_FLAG_SECDED;
	if (ecc_on) {
		if (scrub_disabled)
			debugf3("MC: " __FILE__ ": %s(): mci = %p - "
				"Scrubbing disabled! EAP: %#0x\n", __func__,
				mci, eapr);
	} else
		mci->edac_cap = EDAC_FLAG_NONE;

	mci->mod_name = BS_MOD_STR;
	mci->mod_ver = "$Revision: 1.1.2.6 $";
	mci->ctl_name = "R82600";
	mci->edac_check = r82600_check;
	mci->ctl_page_to_phys = NULL;

	for (index = 0; index < mci->nr_csrows; index++) {
		struct csrow_info *csrow = &mci->csrows[index];
		u8 drbar;	/* sDram Row Boundry Address Register */
		u32 row_high_limit;
		u32 row_base;

		/* find the DRAM Chip Select Base address and mask */
		pci_read_config_byte(mci->pdev, R82600_DRBA + index, &drbar);

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

		row_high_limit = ((u32) drbar << 24);
/*		row_high_limit = ((u32)drbar << 24) | 0xffffffUL; */

		debugf1("MC%d: " __FILE__ ": %s() Row=%d, "
			"Boundry Address=%#0x, Last = %#0x \n",
			mci->mc_idx, __func__, index, row_high_limit,
			row_high_limit_last);

		/* Empty row [p.57] */
		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;
		/* Error address is top 19 bits - so granularity is      *
		 * 14 bits                                               */
		csrow->grain = 1 << 14;
		csrow->mtype = reg_sdram ? MEM_RDDR : MEM_DDR;
		/* FIXME - check that this is unknowable with this chipset */
		csrow->dtype = DEV_UNKNOWN;

		/* Mode is global on 82600 */
		csrow->edac_mode = ecc_on ? EDAC_SECDED : EDAC_NONE;
		row_high_limit_last = row_high_limit;
	}

	/* clear counters */
	/* FIXME should we? */

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

	/* get this far and it's successful */

	/* Clear error flags to allow next error to be reported [p.62] */
	/* Test systems seem to always have the UE flag raised on boot */

	eap_init_bits = BIT(0) & BIT(1);
	if (disable_hardware_scrub) {
		eap_init_bits |= BIT(31);
		debugf3("MC: " __FILE__ ": %s(): Disabling Hardware Scrub "
			"(scrub on error)\n", __func__);
	}

	pci_write_bits32(mci->pdev, R82600_EAP, eap_init_bits,
			 eap_init_bits);

	debugf3("MC: " __FILE__ ": %s(): success\n", __func__);
	return 0;

fail:
	if (mci)
		edac_mc_free(mci);

	return rc;
}

/* returns count (>= 0), or negative on error */
static int __devinit r82600_init_one(struct pci_dev *pdev,
				     const struct pci_device_id *ent)
{
	debugf0("MC: " __FILE__ ": %s()\n", __func__);

	/* don't need to call pci_device_enable() */
	return r82600_probe1(pdev, ent->driver_data);
}


static void __devexit r82600_remove_one(struct pci_dev *pdev)
{
	struct mem_ctl_info *mci;

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

	if (((mci = edac_mc_find_mci_by_pdev(pdev)) != NULL) &&
	    !edac_mc_del_mc(mci))
		edac_mc_free(mci);
}


static const struct pci_device_id r82600_pci_tbl[] __devinitdata = {
	{PCI_DEVICE(PCI_VENDOR_ID_RADISYS, R82600_BRIDGE_ID)},
	{0,}			/* 0 terminated list. */
};

MODULE_DEVICE_TABLE(pci, r82600_pci_tbl);


static struct pci_driver r82600_driver = {
	.name = BS_MOD_STR,
	.probe = r82600_init_one,
	.remove = __devexit_p(r82600_remove_one),
	.id_table = r82600_pci_tbl,
};


static int __init r82600_init(void)
{
	return pci_register_driver(&r82600_driver);
}


static void __exit r82600_exit(void)
{
	pci_unregister_driver(&r82600_driver);
}


module_init(r82600_init);
module_exit(r82600_exit);


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tim Small <tim@buttersideup.com> - WPAD Ltd. "
	      "on behalf of EADS Astrium");
MODULE_DESCRIPTION("MC support for Radisys 82600 memory controllers");

module_param(disable_hardware_scrub, bool, 0644);
MODULE_PARM_DESC(disable_hardware_scrub,
		 "If set, disable the chipset's automatic scrub for CEs");