/*
 * Intel I/OAT DMA Linux driver
 * Copyright(c) 2007 - 2009 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 */

#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/dca.h>

/* either a kernel change is needed, or we need something like this in kernel */
#ifndef CONFIG_SMP
#include <asm/smp.h>
#undef cpu_physical_id
#define cpu_physical_id(cpu) (cpuid_ebx(1) >> 24)
#endif

#include "dma.h"
#include "registers.h"

/*
 * Bit 7 of a tag map entry is the "valid" bit, if it is set then bits 0:6
 * contain the bit number of the APIC ID to map into the DCA tag.  If the valid
 * bit is not set, then the value must be 0 or 1 and defines the bit in the tag.
 */
#define DCA_TAG_MAP_VALID 0x80

#define DCA3_TAG_MAP_BIT_TO_INV 0x80
#define DCA3_TAG_MAP_BIT_TO_SEL 0x40
#define DCA3_TAG_MAP_LITERAL_VAL 0x1

#define DCA_TAG_MAP_MASK 0xDF

/* expected tag map bytes for I/OAT ver.2 */
#define DCA2_TAG_MAP_BYTE0 0x80
#define DCA2_TAG_MAP_BYTE1 0x0
#define DCA2_TAG_MAP_BYTE2 0x81
#define DCA2_TAG_MAP_BYTE3 0x82
#define DCA2_TAG_MAP_BYTE4 0x82

/* verify if tag map matches expected values */
static inline int dca2_tag_map_valid(u8 *tag_map)
{
        return ((tag_map[0] == DCA2_TAG_MAP_BYTE0) &&
                (tag_map[1] == DCA2_TAG_MAP_BYTE1) &&
                (tag_map[2] == DCA2_TAG_MAP_BYTE2) &&
                (tag_map[3] == DCA2_TAG_MAP_BYTE3) &&
                (tag_map[4] == DCA2_TAG_MAP_BYTE4));
}

/*
 * "Legacy" DCA systems do not implement the DCA register set in the
 * I/OAT device.  Software needs direct support for their tag mappings.
 */

#define APICID_BIT(x)           (DCA_TAG_MAP_VALID | (x))
#define IOAT_TAG_MAP_LEN        8

static u8 ioat_tag_map_BNB[IOAT_TAG_MAP_LEN] = {
        1, APICID_BIT(1), APICID_BIT(2), APICID_BIT(2), };
static u8 ioat_tag_map_SCNB[IOAT_TAG_MAP_LEN] = {
        1, APICID_BIT(1), APICID_BIT(2), APICID_BIT(2), };
static u8 ioat_tag_map_CNB[IOAT_TAG_MAP_LEN] = {
        1, APICID_BIT(1), APICID_BIT(3), APICID_BIT(4), APICID_BIT(2), };
static u8 ioat_tag_map_UNISYS[IOAT_TAG_MAP_LEN] = { 0 };

/* pack PCI B/D/F into a u16 */
static inline u16 dcaid_from_pcidev(struct pci_dev *pci)
{
        return (pci->bus->number << 8) | pci->devfn;
}

static int dca_enabled_in_bios(struct pci_dev *pdev)
{
        /* CPUID level 9 returns DCA configuration */
        /* Bit 0 indicates DCA enabled by the BIOS */
        unsigned long cpuid_level_9;
        int res;

        cpuid_level_9 = cpuid_eax(9);
        res = test_bit(0, &cpuid_level_9);
        if (!res)
                dev_dbg(&pdev->dev, "DCA is disabled in BIOS\n");

        return res;
}

int system_has_dca_enabled(struct pci_dev *pdev)
{
        if (boot_cpu_has(X86_FEATURE_DCA))
                return dca_enabled_in_bios(pdev);

        dev_dbg(&pdev->dev, "boot cpu doesn't have X86_FEATURE_DCA\n");
        return 0;
}

struct ioat_dca_slot {
        struct pci_dev *pdev;   /* requester device */
        u16 rid;                /* requester id, as used by IOAT */
};

#define IOAT_DCA_MAX_REQ 6
#define IOAT3_DCA_MAX_REQ 2

struct ioat_dca_priv {
        void __iomem            *iobase;
        void __iomem            *dca_base;
        int                      max_requesters;
        int                      requester_count;
        u8                       tag_map[IOAT_TAG_MAP_LEN];
        struct ioat_dca_slot     req_slots[0];
};

/* 5000 series chipset DCA Port Requester ID Table Entry Format
 * [15:8]       PCI-Express Bus Number
 * [7:3]        PCI-Express Device Number
 * [2:0]        PCI-Express Function Number
 *
 * 5000 series chipset DCA control register format
 * [7:1]        Reserved (0)
 * [0]          Ignore Function Number
 */

static int ioat_dca_add_requester(struct dca_provider *dca, struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;
        u16 id;

        /* This implementation only supports PCI-Express */
        if (dev->bus != &pci_bus_type)
                return -ENODEV;
        pdev = to_pci_dev(dev);
        id = dcaid_from_pcidev(pdev);

        if (ioatdca->requester_count == ioatdca->max_requesters)
                return -ENODEV;

        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == NULL) {
                        /* found an empty slot */
                        ioatdca->requester_count++;
                        ioatdca->req_slots[i].pdev = pdev;
                        ioatdca->req_slots[i].rid = id;
                        writew(id, ioatdca->dca_base + (i * 4));
                        /* make sure the ignore function bit is off */
                        writeb(0, ioatdca->dca_base + (i * 4) + 2);
                        return i;
                }
        }
        /* Error, ioatdma->requester_count is out of whack */
        return -EFAULT;
}

static int ioat_dca_remove_requester(struct dca_provider *dca,
                                     struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;

        /* This implementation only supports PCI-Express */
        if (dev->bus != &pci_bus_type)
                return -ENODEV;
        pdev = to_pci_dev(dev);

        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == pdev) {
                        writew(0, ioatdca->dca_base + (i * 4));
                        ioatdca->req_slots[i].pdev = NULL;
                        ioatdca->req_slots[i].rid = 0;
                        ioatdca->requester_count--;
                        return i;
                }
        }
        return -ENODEV;
}

static u8 ioat_dca_get_tag(struct dca_provider *dca,
                           struct device *dev,
                           int cpu)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        int i, apic_id, bit, value;
        u8 entry, tag;

        tag = 0;
        apic_id = cpu_physical_id(cpu);

        for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
                entry = ioatdca->tag_map[i];
                if (entry & DCA_TAG_MAP_VALID) {
                        bit = entry & ~DCA_TAG_MAP_VALID;
                        value = (apic_id & (1 << bit)) ? 1 : 0;
                } else {
                        value = entry ? 1 : 0;
                }
                tag |= (value << i);
        }
        return tag;
}

static int ioat_dca_dev_managed(struct dca_provider *dca,
                                struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;

        pdev = to_pci_dev(dev);
        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == pdev)
                        return 1;
        }
        return 0;
}

static struct dca_ops ioat_dca_ops = {
        .add_requester          = ioat_dca_add_requester,
        .remove_requester       = ioat_dca_remove_requester,
        .get_tag                = ioat_dca_get_tag,
        .dev_managed            = ioat_dca_dev_managed,
};


struct dca_provider * __devinit
ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
{
        struct dca_provider *dca;
        struct ioat_dca_priv *ioatdca;
        u8 *tag_map = NULL;
        int i;
        int err;
        u8 version;
        u8 max_requesters;

        if (!system_has_dca_enabled(pdev))
                return NULL;

        /* I/OAT v1 systems must have a known tag_map to support DCA */
        switch (pdev->vendor) {
        case PCI_VENDOR_ID_INTEL:
                switch (pdev->device) {
                case PCI_DEVICE_ID_INTEL_IOAT:
                        tag_map = ioat_tag_map_BNB;
                        break;
                case PCI_DEVICE_ID_INTEL_IOAT_CNB:
                        tag_map = ioat_tag_map_CNB;
                        break;
                case PCI_DEVICE_ID_INTEL_IOAT_SCNB:
                        tag_map = ioat_tag_map_SCNB;
                        break;
                }
                break;
        case PCI_VENDOR_ID_UNISYS:
                switch (pdev->device) {
                case PCI_DEVICE_ID_UNISYS_DMA_DIRECTOR:
                        tag_map = ioat_tag_map_UNISYS;
                        break;
                }
                break;
        }
        if (tag_map == NULL)
                return NULL;

        version = readb(iobase + IOAT_VER_OFFSET);
        if (version == IOAT_VER_3_0)
                max_requesters = IOAT3_DCA_MAX_REQ;
        else
                max_requesters = IOAT_DCA_MAX_REQ;

        dca = alloc_dca_provider(&ioat_dca_ops,
                        sizeof(*ioatdca) +
                        (sizeof(struct ioat_dca_slot) * max_requesters));
        if (!dca)
                return NULL;

        ioatdca = dca_priv(dca);
        ioatdca->max_requesters = max_requesters;
        ioatdca->dca_base = iobase + 0x54;

        /* copy over the APIC ID to DCA tag mapping */
        for (i = 0; i < IOAT_TAG_MAP_LEN; i++)
                ioatdca->tag_map[i] = tag_map[i];

        err = register_dca_provider(dca, &pdev->dev);
        if (err) {
                free_dca_provider(dca);
                return NULL;
        }

        return dca;
}


static int ioat2_dca_add_requester(struct dca_provider *dca, struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;
        u16 id;
        u16 global_req_table;

        /* This implementation only supports PCI-Express */
        if (dev->bus != &pci_bus_type)
                return -ENODEV;
        pdev = to_pci_dev(dev);
        id = dcaid_from_pcidev(pdev);

        if (ioatdca->requester_count == ioatdca->max_requesters)
                return -ENODEV;

        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == NULL) {
                        /* found an empty slot */
                        ioatdca->requester_count++;
                        ioatdca->req_slots[i].pdev = pdev;
                        ioatdca->req_slots[i].rid = id;
                        global_req_table =
                              readw(ioatdca->dca_base + IOAT_DCA_GREQID_OFFSET);
                        writel(id | IOAT_DCA_GREQID_VALID,
                               ioatdca->iobase + global_req_table + (i * 4));
                        return i;
                }
        }
        /* Error, ioatdma->requester_count is out of whack */
        return -EFAULT;
}

static int ioat2_dca_remove_requester(struct dca_provider *dca,
                                      struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;
        u16 global_req_table;

        /* This implementation only supports PCI-Express */
        if (dev->bus != &pci_bus_type)
                return -ENODEV;
        pdev = to_pci_dev(dev);

        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == pdev) {
                        global_req_table =
                              readw(ioatdca->dca_base + IOAT_DCA_GREQID_OFFSET);
                        writel(0, ioatdca->iobase + global_req_table + (i * 4));
                        ioatdca->req_slots[i].pdev = NULL;
                        ioatdca->req_slots[i].rid = 0;
                        ioatdca->requester_count--;
                        return i;
                }
        }
        return -ENODEV;
}

static u8 ioat2_dca_get_tag(struct dca_provider *dca,
                            struct device *dev,
                            int cpu)
{
        u8 tag;

        tag = ioat_dca_get_tag(dca, dev, cpu);
        tag = (~tag) & 0x1F;
        return tag;
}

static struct dca_ops ioat2_dca_ops = {
        .add_requester          = ioat2_dca_add_requester,
        .remove_requester       = ioat2_dca_remove_requester,
        .get_tag                = ioat2_dca_get_tag,
        .dev_managed            = ioat_dca_dev_managed,
};

static int ioat2_dca_count_dca_slots(void __iomem *iobase, u16 dca_offset)
{
        int slots = 0;
        u32 req;
        u16 global_req_table;

        global_req_table = readw(iobase + dca_offset + IOAT_DCA_GREQID_OFFSET);
        if (global_req_table == 0)
                return 0;
        do {
                req = readl(iobase + global_req_table + (slots * sizeof(u32)));
                slots++;
        } while ((req & IOAT_DCA_GREQID_LASTID) == 0);

        return slots;
}

struct dca_provider * __devinit
ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase)
{
        struct dca_provider *dca;
        struct ioat_dca_priv *ioatdca;
        int slots;
        int i;
        int err;
        u32 tag_map;
        u16 dca_offset;
        u16 csi_fsb_control;
        u16 pcie_control;
        u8 bit;

        if (!system_has_dca_enabled(pdev))
                return NULL;

        dca_offset = readw(iobase + IOAT_DCAOFFSET_OFFSET);
        if (dca_offset == 0)
                return NULL;

        slots = ioat2_dca_count_dca_slots(iobase, dca_offset);
        if (slots == 0)
                return NULL;

        dca = alloc_dca_provider(&ioat2_dca_ops,
                                 sizeof(*ioatdca)
                                      + (sizeof(struct ioat_dca_slot) * slots));
        if (!dca)
                return NULL;

        ioatdca = dca_priv(dca);
        ioatdca->iobase = iobase;
        ioatdca->dca_base = iobase + dca_offset;
        ioatdca->max_requesters = slots;

        /* some bios might not know to turn these on */
        csi_fsb_control = readw(ioatdca->dca_base + IOAT_FSB_CAP_ENABLE_OFFSET);
        if ((csi_fsb_control & IOAT_FSB_CAP_ENABLE_PREFETCH) == 0) {
                csi_fsb_control |= IOAT_FSB_CAP_ENABLE_PREFETCH;
                writew(csi_fsb_control,
                       ioatdca->dca_base + IOAT_FSB_CAP_ENABLE_OFFSET);
        }
        pcie_control = readw(ioatdca->dca_base + IOAT_PCI_CAP_ENABLE_OFFSET);
        if ((pcie_control & IOAT_PCI_CAP_ENABLE_MEMWR) == 0) {
                pcie_control |= IOAT_PCI_CAP_ENABLE_MEMWR;
                writew(pcie_control,
                       ioatdca->dca_base + IOAT_PCI_CAP_ENABLE_OFFSET);
        }


        /* TODO version, compatibility and configuration checks */

        /* copy out the APIC to DCA tag map */
        tag_map = readl(ioatdca->dca_base + IOAT_APICID_TAG_MAP_OFFSET);
        for (i = 0; i < 5; i++) {
                bit = (tag_map >> (4 * i)) & 0x0f;
                if (bit < 8)
                        ioatdca->tag_map[i] = bit | DCA_TAG_MAP_VALID;
                else
                        ioatdca->tag_map[i] = 0;
        }

        if (!dca2_tag_map_valid(ioatdca->tag_map)) {
                dev_err(&pdev->dev, "APICID_TAG_MAP set incorrectly by BIOS, "
                        "disabling DCA\n");
                free_dca_provider(dca);
                return NULL;
        }

        err = register_dca_provider(dca, &pdev->dev);
        if (err) {
                free_dca_provider(dca);
                return NULL;
        }

        return dca;
}

static int ioat3_dca_add_requester(struct dca_provider *dca, struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;
        u16 id;
        u16 global_req_table;

        /* This implementation only supports PCI-Express */
        if (dev->bus != &pci_bus_type)
                return -ENODEV;
        pdev = to_pci_dev(dev);
        id = dcaid_from_pcidev(pdev);

        if (ioatdca->requester_count == ioatdca->max_requesters)
                return -ENODEV;

        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == NULL) {
                        /* found an empty slot */
                        ioatdca->requester_count++;
                        ioatdca->req_slots[i].pdev = pdev;
                        ioatdca->req_slots[i].rid = id;
                        global_req_table =
                              readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
                        writel(id | IOAT_DCA_GREQID_VALID,
                               ioatdca->iobase + global_req_table + (i * 4));
                        return i;
                }
        }
        /* Error, ioatdma->requester_count is out of whack */
        return -EFAULT;
}

static int ioat3_dca_remove_requester(struct dca_provider *dca,
                                      struct device *dev)
{
        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        struct pci_dev *pdev;
        int i;
        u16 global_req_table;

        /* This implementation only supports PCI-Express */
        if (dev->bus != &pci_bus_type)
                return -ENODEV;
        pdev = to_pci_dev(dev);

        for (i = 0; i < ioatdca->max_requesters; i++) {
                if (ioatdca->req_slots[i].pdev == pdev) {
                        global_req_table =
                              readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
                        writel(0, ioatdca->iobase + global_req_table + (i * 4));
                        ioatdca->req_slots[i].pdev = NULL;
                        ioatdca->req_slots[i].rid = 0;
                        ioatdca->requester_count--;
                        return i;
                }
        }
        return -ENODEV;
}

static u8 ioat3_dca_get_tag(struct dca_provider *dca,
                            struct device *dev,
                            int cpu)
{
        u8 tag;

        struct ioat_dca_priv *ioatdca = dca_priv(dca);
        int i, apic_id, bit, value;
        u8 entry;

        tag = 0;
        apic_id = cpu_physical_id(cpu);

        for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
                entry = ioatdca->tag_map[i];
                if (entry & DCA3_TAG_MAP_BIT_TO_SEL) {
                        bit = entry &
                                ~(DCA3_TAG_MAP_BIT_TO_SEL | DCA3_TAG_MAP_BIT_TO_INV);
                        value = (apic_id & (1 << bit)) ? 1 : 0;
                } else if (entry & DCA3_TAG_MAP_BIT_TO_INV) {
                        bit = entry & ~DCA3_TAG_MAP_BIT_TO_INV;
                        value = (apic_id & (1 << bit)) ? 0 : 1;
                } else {
                        value = (entry & DCA3_TAG_MAP_LITERAL_VAL) ? 1 : 0;
                }
                tag |= (value << i);
        }

        return tag;
}

static struct dca_ops ioat3_dca_ops = {
        .add_requester          = ioat3_dca_add_requester,
        .remove_requester       = ioat3_dca_remove_requester,
        .get_tag                = ioat3_dca_get_tag,
        .dev_managed            = ioat_dca_dev_managed,
};

static int ioat3_dca_count_dca_slots(void *iobase, u16 dca_offset)
{
        int slots = 0;
        u32 req;
        u16 global_req_table;

        global_req_table = readw(iobase + dca_offset + IOAT3_DCA_GREQID_OFFSET);
        if (global_req_table == 0)
                return 0;

        do {
                req = readl(iobase + global_req_table + (slots * sizeof(u32)));
                slots++;
        } while ((req & IOAT_DCA_GREQID_LASTID) == 0);

        return slots;
}

struct dca_provider * __devinit
ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase)
{
        struct dca_provider *dca;
        struct ioat_dca_priv *ioatdca;
        int slots;
        int i;
        int err;
        u16 dca_offset;
        u16 csi_fsb_control;
        u16 pcie_control;
        u8 bit;

        union {
                u64 full;
                struct {
                        u32 low;
                        u32 high;
                };
        } tag_map;

        if (!system_has_dca_enabled(pdev))
                return NULL;

        dca_offset = readw(iobase + IOAT_DCAOFFSET_OFFSET);
        if (dca_offset == 0)
                return NULL;

        slots = ioat3_dca_count_dca_slots(iobase, dca_offset);
        if (slots == 0)
                return NULL;

        dca = alloc_dca_provider(&ioat3_dca_ops,
                                 sizeof(*ioatdca)
                                      + (sizeof(struct ioat_dca_slot) * slots));
        if (!dca)
                return NULL;

        ioatdca = dca_priv(dca);
        ioatdca->iobase = iobase;
        ioatdca->dca_base = iobase + dca_offset;
        ioatdca->max_requesters = slots;

        /* some bios might not know to turn these on */
        csi_fsb_control = readw(ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
        if ((csi_fsb_control & IOAT3_CSI_CONTROL_PREFETCH) == 0) {
                csi_fsb_control |= IOAT3_CSI_CONTROL_PREFETCH;
                writew(csi_fsb_control,
                       ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
        }
        pcie_control = readw(ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
        if ((pcie_control & IOAT3_PCI_CONTROL_MEMWR) == 0) {
                pcie_control |= IOAT3_PCI_CONTROL_MEMWR;
                writew(pcie_control,
                       ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
        }


        /* TODO version, compatibility and configuration checks */

        /* copy out the APIC to DCA tag map */
        tag_map.low =
                readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_LOW);
        tag_map.high =
                readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_HIGH);
        for (i = 0; i < 8; i++) {
                bit = tag_map.full >> (8 * i);
                ioatdca->tag_map[i] = bit & DCA_TAG_MAP_MASK;
        }

        err = register_dca_provider(dca, &pdev->dev);
        if (err) {
                free_dca_provider(dca);
                return NULL;
        }

        return dca;
}