/*
** I/O Sapic Driver - PCI interrupt line support
**
**      (c) Copyright 1999 Grant Grundler
**      (c) Copyright 1999 Hewlett-Packard Company
**
**      This program is free software; you can redistribute it and/or modify
**      it under the terms of the GNU General Public License as published by
**      the Free Software Foundation; either version 2 of the License, or
**      (at your option) any later version.
**
** The I/O sapic driver manages the Interrupt Redirection Table which is
** the control logic to convert PCI line based interrupts into a Message
** Signaled Interrupt (aka Transaction Based Interrupt, TBI).
**
** Acronyms
** --------
** HPA  Hard Physical Address (aka MMIO address)
** IRQ  Interrupt ReQuest. Implies Line based interrupt.
** IRT  Interrupt Routing Table (provided by PAT firmware)
** IRdT Interrupt Redirection Table. IRQ line to TXN ADDR/DATA
**      table which is implemented in I/O SAPIC.
** ISR  Interrupt Service Routine. aka Interrupt handler.
** MSI  Message Signaled Interrupt. PCI 2.2 functionality.
**      aka Transaction Based Interrupt (or TBI).
** PA   Precision Architecture. HP's RISC architecture.
** RISC Reduced Instruction Set Computer.
**
**
** What's a Message Signalled Interrupt?
** -------------------------------------
** MSI is a write transaction which targets a processor and is similar
** to a processor write to memory or MMIO. MSIs can be generated by I/O
** devices as well as processors and require *architecture* to work.
**
** PA only supports MSI. So I/O subsystems must either natively generate
** MSIs (e.g. GSC or HP-PB) or convert line based interrupts into MSIs
** (e.g. PCI and EISA).  IA64 supports MSIs via a "local SAPIC" which
** acts on behalf of a processor.
**
** MSI allows any I/O device to interrupt any processor. This makes
** load balancing of the interrupt processing possible on an SMP platform.
** Interrupts are also ordered WRT to DMA data.  It's possible on I/O
** coherent systems to completely eliminate PIO reads from the interrupt
** path. The device and driver must be designed and implemented to
** guarantee all DMA has been issued (issues about atomicity here)
** before the MSI is issued. I/O status can then safely be read from
** DMA'd data by the ISR.
**
**
** PA Firmware
** -----------
** PA-RISC platforms have two fundamentally different types of firmware.
** For PCI devices, "Legacy" PDC initializes the "INTERRUPT_LINE" register
** and BARs similar to a traditional PC BIOS.
** The newer "PAT" firmware supports PDC calls which return tables.
** PAT firmware only initializes the PCI Console and Boot interface.
** With these tables, the OS can program all other PCI devices.
**
** One such PAT PDC call returns the "Interrupt Routing Table" (IRT).
** The IRT maps each PCI slot's INTA-D "output" line to an I/O SAPIC
** input line.  If the IRT is not available, this driver assumes
** INTERRUPT_LINE register has been programmed by firmware. The latter
** case also means online addition of PCI cards can NOT be supported
** even if HW support is present.
**
** All platforms with PAT firmware to date (Oct 1999) use one Interrupt
** Routing Table for the entire platform.
**
** Where's the iosapic?
** --------------------
** I/O sapic is part of the "Core Electronics Complex". And on HP platforms
** it's integrated as part of the PCI bus adapter, "lba".  So no bus walk
** will discover I/O Sapic. I/O Sapic driver learns about each device
** when lba driver advertises the presence of the I/O sapic by calling
** iosapic_register().
**
**
** IRQ handling notes
** ------------------
** The IO-SAPIC can indicate to the CPU which interrupt was asserted.
** So, unlike the GSC-ASIC and Dino, we allocate one CPU interrupt per
** IO-SAPIC interrupt and call the device driver's handler directly.
** The IO-SAPIC driver hijacks the CPU interrupt handler so it can
** issue the End Of Interrupt command to the IO-SAPIC.
**
** Overview of exported iosapic functions
** --------------------------------------
** (caveat: code isn't finished yet - this is just the plan)
**
** iosapic_init:
**   o initialize globals (lock, etc)
**   o try to read IRT. Presence of IRT determines if this is
**     a PAT platform or not.
**
** iosapic_register():
**   o create iosapic_info instance data structure
**   o allocate vector_info array for this iosapic
**   o initialize vector_info - read corresponding IRdT?
**
** iosapic_xlate_pin: (only called by fixup_irq for PAT platform)
**   o intr_pin = read cfg (INTERRUPT_PIN);
**   o if (device under PCI-PCI bridge)
**               translate slot/pin
**
** iosapic_fixup_irq:
**   o if PAT platform (IRT present)
**         intr_pin = iosapic_xlate_pin(isi,pcidev):
**         intr_line = find IRT entry(isi, PCI_SLOT(pcidev), intr_pin)
**         save IRT entry into vector_info later
**         write cfg INTERRUPT_LINE (with intr_line)?
**     else
**         intr_line = pcidev->irq
**         IRT pointer = NULL
**     endif
**   o locate vector_info (needs: isi, intr_line)
**   o allocate processor "irq" and get txn_addr/data
**   o request_irq(processor_irq,  iosapic_interrupt, vector_info,...)
**
** iosapic_enable_irq:
**   o clear any pending IRQ on that line
**   o enable IRdT - call enable_irq(vector[line]->processor_irq)
**   o write EOI in case line is already asserted.
**
** iosapic_disable_irq:
**   o disable IRdT - call disable_irq(vector[line]->processor_irq)
*/


/* FIXME: determine which include files are really needed */
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/interrupt.h>

#include <asm/byteorder.h>      /* get in-line asm for swab */
#include <asm/pdc.h>
#include <asm/pdcpat.h>
#include <asm/page.h>
#include <asm/system.h>
#include <asm/io.h>             /* read/write functions */
#ifdef CONFIG_SUPERIO
#include <asm/superio.h>
#endif

#include <asm/ropes.h>
#include "./iosapic_private.h"

#define MODULE_NAME "iosapic"

/* "local" compile flags */
#undef PCI_BRIDGE_FUNCS
#undef DEBUG_IOSAPIC
#undef DEBUG_IOSAPIC_IRT


#ifdef DEBUG_IOSAPIC
#define DBG(x...) printk(x)
#else /* DEBUG_IOSAPIC */
#define DBG(x...)
#endif /* DEBUG_IOSAPIC */

#ifdef DEBUG_IOSAPIC_IRT
#define DBG_IRT(x...) printk(x)
#else
#define DBG_IRT(x...)
#endif

#ifdef CONFIG_64BIT
#define COMPARE_IRTE_ADDR(irte, hpa)    ((irte)->dest_iosapic_addr == (hpa))
#else
#define COMPARE_IRTE_ADDR(irte, hpa)    \
                ((irte)->dest_iosapic_addr == ((hpa) | 0xffffffff00000000ULL))
#endif

#define IOSAPIC_REG_SELECT              0x00
#define IOSAPIC_REG_WINDOW              0x10
#define IOSAPIC_REG_EOI                 0x40

#define IOSAPIC_REG_VERSION             0x1

#define IOSAPIC_IRDT_ENTRY(idx)         (0x10+(idx)*2)
#define IOSAPIC_IRDT_ENTRY_HI(idx)      (0x11+(idx)*2)

static inline unsigned int iosapic_read(void __iomem *iosapic, unsigned int reg)
{
        writel(reg, iosapic + IOSAPIC_REG_SELECT);
        return readl(iosapic + IOSAPIC_REG_WINDOW);
}

static inline void iosapic_write(void __iomem *iosapic, unsigned int reg, u32 val)
{
        writel(reg, iosapic + IOSAPIC_REG_SELECT);
        writel(val, iosapic + IOSAPIC_REG_WINDOW);
}

#define IOSAPIC_VERSION_MASK    0x000000ff
#define IOSAPIC_VERSION(ver)    ((int) (ver & IOSAPIC_VERSION_MASK))

#define IOSAPIC_MAX_ENTRY_MASK          0x00ff0000
#define IOSAPIC_MAX_ENTRY_SHIFT         0x10
#define IOSAPIC_IRDT_MAX_ENTRY(ver)     \
        (int) (((ver) & IOSAPIC_MAX_ENTRY_MASK) >> IOSAPIC_MAX_ENTRY_SHIFT)

/* bits in the "low" I/O Sapic IRdT entry */
#define IOSAPIC_IRDT_ENABLE       0x10000
#define IOSAPIC_IRDT_PO_LOW       0x02000
#define IOSAPIC_IRDT_LEVEL_TRIG   0x08000
#define IOSAPIC_IRDT_MODE_LPRI    0x00100

/* bits in the "high" I/O Sapic IRdT entry */
#define IOSAPIC_IRDT_ID_EID_SHIFT              0x10


static DEFINE_SPINLOCK(iosapic_lock);

static inline void iosapic_eoi(void __iomem *addr, unsigned int data)
{
        __raw_writel(data, addr);
}

/*
** REVISIT: future platforms may have more than one IRT.
** If so, the following three fields form a structure which
** then be linked into a list. Names are chosen to make searching
** for them easy - not necessarily accurate (eg "cell").
**
** Alternative: iosapic_info could point to the IRT it's in.
** iosapic_register() could search a list of IRT's.
*/
static struct irt_entry *irt_cell;
static size_t irt_num_entry;

static struct irt_entry *iosapic_alloc_irt(int num_entries)
{
        unsigned long a;

        /* The IRT needs to be 8-byte aligned for the PDC call. 
         * Normally kmalloc would guarantee larger alignment, but
         * if CONFIG_DEBUG_SLAB is enabled, then we can get only
         * 4-byte alignment on 32-bit kernels
         */
        a = (unsigned long)kmalloc(sizeof(struct irt_entry) * num_entries + 8, GFP_KERNEL);
        a = (a + 7UL) & ~7UL;
        return (struct irt_entry *)a;
}

/**
 * iosapic_load_irt - Fill in the interrupt routing table
 * @cell_num: The cell number of the CPU we're currently executing on
 * @irt: The address to place the new IRT at
 * @return The number of entries found
 *
 * The "Get PCI INT Routing Table Size" option returns the number of 
 * entries in the PCI interrupt routing table for the cell specified 
 * in the cell_number argument.  The cell number must be for a cell 
 * within the caller's protection domain.
 *
 * The "Get PCI INT Routing Table" option returns, for the cell 
 * specified in the cell_number argument, the PCI interrupt routing 
 * table in the caller allocated memory pointed to by mem_addr.
 * We assume the IRT only contains entries for I/O SAPIC and
 * calculate the size based on the size of I/O sapic entries.
 *
 * The PCI interrupt routing table entry format is derived from the
 * IA64 SAL Specification 2.4.   The PCI interrupt routing table defines
 * the routing of PCI interrupt signals between the PCI device output
 * "pins" and the IO SAPICs' input "lines" (including core I/O PCI
 * devices).  This table does NOT include information for devices/slots
 * behind PCI to PCI bridges. See PCI to PCI Bridge Architecture Spec.
 * for the architected method of routing of IRQ's behind PPB's.
 */


static int __init
iosapic_load_irt(unsigned long cell_num, struct irt_entry **irt)
{
        long status;              /* PDC return value status */
        struct irt_entry *table;  /* start of interrupt routing tbl */
        unsigned long num_entries = 0UL;

        BUG_ON(!irt);

        if (is_pdc_pat()) {
                /* Use pat pdc routine to get interrupt routing table size */
                DBG("calling get_irt_size (cell %ld)\n", cell_num);
                status = pdc_pat_get_irt_size(&num_entries, cell_num);
                DBG("get_irt_size: %ld\n", status);

                BUG_ON(status != PDC_OK);
                BUG_ON(num_entries == 0);

                /*
                ** allocate memory for interrupt routing table
                ** This interface isn't really right. We are assuming
                ** the contents of the table are exclusively
                ** for I/O sapic devices.
                */
                table = iosapic_alloc_irt(num_entries);
                if (table == NULL) {
                        printk(KERN_WARNING MODULE_NAME ": read_irt : can "
                                        "not alloc mem for IRT\n");
                        return 0;
                }

                /* get PCI INT routing table */
                status = pdc_pat_get_irt(table, cell_num);
                DBG("pdc_pat_get_irt: %ld\n", status);
                WARN_ON(status != PDC_OK);
        } else {
                /*
                ** C3000/J5000 (and similar) platforms with Sprockets PDC
                ** will return exactly one IRT for all iosapics.
                ** So if we have one, don't need to get it again.
                */
                if (irt_cell)
                        return 0;

                /* Should be using the Elroy's HPA, but it's ignored anyway */
                status = pdc_pci_irt_size(&num_entries, 0);
                DBG("pdc_pci_irt_size: %ld\n", status);

                if (status != PDC_OK) {
                        /* Not a "legacy" system with I/O SAPIC either */
                        return 0;
                }

                BUG_ON(num_entries == 0);

                table = iosapic_alloc_irt(num_entries);
                if (!table) {
                        printk(KERN_WARNING MODULE_NAME ": read_irt : can "
                                        "not alloc mem for IRT\n");
                        return 0;
                }

                /* HPA ignored by this call too. */
                status = pdc_pci_irt(num_entries, 0, table);
                BUG_ON(status != PDC_OK);
        }

        /* return interrupt table address */
        *irt = table;

#ifdef DEBUG_IOSAPIC_IRT
{
        struct irt_entry *p = table;
        int i;

        printk(MODULE_NAME " Interrupt Routing Table (cell %ld)\n", cell_num);
        printk(MODULE_NAME " start = 0x%p num_entries %ld entry_size %d\n",
                table,
                num_entries,
                (int) sizeof(struct irt_entry));

        for (i = 0 ; i < num_entries ; i++, p++) {
                printk(MODULE_NAME " %02x %02x %02x %02x %02x %02x %02x %02x %08x%08x\n",
                p->entry_type, p->entry_length, p->interrupt_type,
                p->polarity_trigger, p->src_bus_irq_devno, p->src_bus_id,
                p->src_seg_id, p->dest_iosapic_intin,
                ((u32 *) p)[2],
                ((u32 *) p)[3]
                );
        }
}
#endif /* DEBUG_IOSAPIC_IRT */

        return num_entries;
}



void __init iosapic_init(void)
{
        unsigned long cell = 0;

        DBG("iosapic_init()\n");

#ifdef __LP64__
        if (is_pdc_pat()) {
                int status;
                struct pdc_pat_cell_num cell_info;

                status = pdc_pat_cell_get_number(&cell_info);
                if (status == PDC_OK) {
                        cell = cell_info.cell_num;
                }
        }
#endif

        /* get interrupt routing table for this cell */
        irt_num_entry = iosapic_load_irt(cell, &irt_cell);
        if (irt_num_entry == 0)
                irt_cell = NULL;        /* old PDC w/o iosapic */
}


/*
** Return the IRT entry in case we need to look something else up.
*/
static struct irt_entry *
irt_find_irqline(struct iosapic_info *isi, u8 slot, u8 intr_pin)
{
        struct irt_entry *i = irt_cell;
        int cnt;        /* track how many entries we've looked at */
        u8 irq_devno = (slot << IRT_DEV_SHIFT) | (intr_pin-1);

        DBG_IRT("irt_find_irqline() SLOT %d pin %d\n", slot, intr_pin);

        for (cnt=0; cnt < irt_num_entry; cnt++, i++) {

                /*
                ** Validate: entry_type, entry_length, interrupt_type
                **
                ** Difference between validate vs compare is the former
                ** should print debug info and is not expected to "fail"
                ** on current platforms.
                */
                if (i->entry_type != IRT_IOSAPIC_TYPE) {
                        DBG_IRT(KERN_WARNING MODULE_NAME ":find_irqline(0x%p): skipping entry %d type %d\n", i, cnt, i->entry_type);
                        continue;
                }
                
                if (i->entry_length != IRT_IOSAPIC_LENGTH) {
                        DBG_IRT(KERN_WARNING MODULE_NAME ":find_irqline(0x%p): skipping entry %d  length %d\n", i, cnt, i->entry_length);
                        continue;
                }

                if (i->interrupt_type != IRT_VECTORED_INTR) {
                        DBG_IRT(KERN_WARNING MODULE_NAME ":find_irqline(0x%p): skipping entry  %d interrupt_type %d\n", i, cnt, i->interrupt_type);
                        continue;
                }

                if (!COMPARE_IRTE_ADDR(i, isi->isi_hpa))
                        continue;

                if ((i->src_bus_irq_devno & IRT_IRQ_DEVNO_MASK) != irq_devno)
                        continue;

                /*
                ** Ignore: src_bus_id and rc_seg_id correlate with
                **         iosapic_info->isi_hpa on HP platforms.
                **         If needed, pass in "PFA" (aka config space addr)
                **         instead of slot.
                */

                /* Found it! */
                return i;
        }

        printk(KERN_WARNING MODULE_NAME ": 0x%lx : no IRT entry for slot %d, pin %d\n",
                        isi->isi_hpa, slot, intr_pin);
        return NULL;
}


/*
** xlate_pin() supports the skewing of IRQ lines done by subsidiary bridges.
** Legacy PDC already does this translation for us and stores it in INTR_LINE.
**
** PAT PDC needs to basically do what legacy PDC does:
** o read PIN
** o adjust PIN in case device is "behind" a PPB
**     (eg 4-port 100BT and SCSI/LAN "Combo Card")
** o convert slot/pin to I/O SAPIC input line.
**
** HP platforms only support:
** o one level of skewing for any number of PPBs
** o only support PCI-PCI Bridges.
*/
static struct irt_entry *
iosapic_xlate_pin(struct iosapic_info *isi, struct pci_dev *pcidev)
{
        u8 intr_pin, intr_slot;

        pci_read_config_byte(pcidev, PCI_INTERRUPT_PIN, &intr_pin);

        DBG_IRT("iosapic_xlate_pin(%s) SLOT %d pin %d\n",
                pcidev->slot_name, PCI_SLOT(pcidev->devfn), intr_pin);

        if (intr_pin == 0) {
                /* The device does NOT support/use IRQ lines.  */
                return NULL;
        }

        /* Check if pcidev behind a PPB */
        if (pcidev->bus->parent) {
                /* Convert pcidev INTR_PIN into something we
                ** can lookup in the IRT.
                */
#ifdef PCI_BRIDGE_FUNCS
                /*
                ** Proposal #1:
                **
                ** call implementation specific translation function
                ** This is architecturally "cleaner". HP-UX doesn't
                ** support other secondary bus types (eg. E/ISA) directly.
                ** May be needed for other processor (eg IA64) architectures
                ** or by some ambitous soul who wants to watch TV.
                */
                if (pci_bridge_funcs->xlate_intr_line) {
                        intr_pin = pci_bridge_funcs->xlate_intr_line(pcidev);
                }
#else   /* PCI_BRIDGE_FUNCS */
                struct pci_bus *p = pcidev->bus;
                /*
                ** Proposal #2:
                ** The "pin" is skewed ((pin + dev - 1) % 4).
                **
                ** This isn't very clean since I/O SAPIC must assume:
                **   - all platforms only have PCI busses.
                **   - only PCI-PCI bridge (eg not PCI-EISA, PCI-PCMCIA)
                **   - IRQ routing is only skewed once regardless of
                **     the number of PPB's between iosapic and device.
                **     (Bit3 expansion chassis follows this rule)
                **
                ** Advantage is it's really easy to implement.
                */
                intr_pin = pci_swizzle_interrupt_pin(pcidev, intr_pin);
#endif /* PCI_BRIDGE_FUNCS */

                /*
                 * Locate the host slot of the PPB.
                 */
                while (p->parent->parent)
                        p = p->parent;

                intr_slot = PCI_SLOT(p->self->devfn);
        } else {
                intr_slot = PCI_SLOT(pcidev->devfn);
        }
        DBG_IRT("iosapic_xlate_pin:  bus %d slot %d pin %d\n",
                                pcidev->bus->secondary, intr_slot, intr_pin);

        return irt_find_irqline(isi, intr_slot, intr_pin);
}

static void iosapic_rd_irt_entry(struct vector_info *vi , u32 *dp0, u32 *dp1)
{
        struct iosapic_info *isp = vi->iosapic;
        u8 idx = vi->irqline;

        *dp0 = iosapic_read(isp->addr, IOSAPIC_IRDT_ENTRY(idx));
        *dp1 = iosapic_read(isp->addr, IOSAPIC_IRDT_ENTRY_HI(idx));
}


static void iosapic_wr_irt_entry(struct vector_info *vi, u32 dp0, u32 dp1)
{
        struct iosapic_info *isp = vi->iosapic;

        DBG_IRT("iosapic_wr_irt_entry(): irq %d hpa %lx 0x%x 0x%x\n",
                vi->irqline, isp->isi_hpa, dp0, dp1);

        iosapic_write(isp->addr, IOSAPIC_IRDT_ENTRY(vi->irqline), dp0);

        /* Read the window register to flush the writes down to HW  */
        dp0 = readl(isp->addr+IOSAPIC_REG_WINDOW);

        iosapic_write(isp->addr, IOSAPIC_IRDT_ENTRY_HI(vi->irqline), dp1);

        /* Read the window register to flush the writes down to HW  */
        dp1 = readl(isp->addr+IOSAPIC_REG_WINDOW);
}

/*
** set_irt prepares the data (dp0, dp1) according to the vector_info
** and target cpu (id_eid).  dp0/dp1 are then used to program I/O SAPIC
** IRdT for the given "vector" (aka IRQ line).
*/
static void
iosapic_set_irt_data( struct vector_info *vi, u32 *dp0, u32 *dp1)
{
        u32 mode = 0;
        struct irt_entry *p = vi->irte;

        if ((p->polarity_trigger & IRT_PO_MASK) == IRT_ACTIVE_LO)
                mode |= IOSAPIC_IRDT_PO_LOW;

        if (((p->polarity_trigger >> IRT_EL_SHIFT) & IRT_EL_MASK) == IRT_LEVEL_TRIG)
                mode |= IOSAPIC_IRDT_LEVEL_TRIG;

        /*
        ** IA64 REVISIT
        ** PA doesn't support EXTINT or LPRIO bits.
        */

        *dp0 = mode | (u32) vi->txn_data;

        /*
        ** Extracting id_eid isn't a real clean way of getting it.
        ** But the encoding is the same for both PA and IA64 platforms.
        */
        if (is_pdc_pat()) {
                /*
                ** PAT PDC just hands it to us "right".
                ** txn_addr comes from cpu_data[x].txn_addr.
                */
                *dp1 = (u32) (vi->txn_addr);
        } else {
                /* 
                ** eg if base_addr == 0xfffa0000),
                **    we want to get 0xa0ff0000.
                **
                ** eid  0x0ff00000 -> 0x00ff0000
                ** id   0x000ff000 -> 0xff000000
                */
                *dp1 = (((u32)vi->txn_addr & 0x0ff00000) >> 4) |
                        (((u32)vi->txn_addr & 0x000ff000) << 12);
        }
        DBG_IRT("iosapic_set_irt_data(): 0x%x 0x%x\n", *dp0, *dp1);
}


static struct vector_info *iosapic_get_vector(unsigned int irq)
{
        struct irq_desc *desc = irq_to_desc(irq);

        return desc->chip_data;
}

static void iosapic_disable_irq(unsigned int irq)
{
        unsigned long flags;
        struct vector_info *vi = iosapic_get_vector(irq);
        u32 d0, d1;

        spin_lock_irqsave(&iosapic_lock, flags);
        iosapic_rd_irt_entry(vi, &d0, &d1);
        d0 |= IOSAPIC_IRDT_ENABLE;
        iosapic_wr_irt_entry(vi, d0, d1);
        spin_unlock_irqrestore(&iosapic_lock, flags);
}

static void iosapic_enable_irq(unsigned int irq)
{
        struct vector_info *vi = iosapic_get_vector(irq);
        u32 d0, d1;

        /* data is initialized by fixup_irq */
        WARN_ON(vi->txn_irq  == 0);

        iosapic_set_irt_data(vi, &d0, &d1);
        iosapic_wr_irt_entry(vi, d0, d1);

#ifdef DEBUG_IOSAPIC_IRT
{
        u32 *t = (u32 *) ((ulong) vi->eoi_addr & ~0xffUL);
        printk("iosapic_enable_irq(): regs %p", vi->eoi_addr);
        for ( ; t < vi->eoi_addr; t++)
                printk(" %x", readl(t));
        printk("\n");
}

printk("iosapic_enable_irq(): sel ");
{
        struct iosapic_info *isp = vi->iosapic;

        for (d0=0x10; d0<0x1e; d0++) {
                d1 = iosapic_read(isp->addr, d0);
                printk(" %x", d1);
        }
}
printk("\n");
#endif

        /*
         * Issuing I/O SAPIC an EOI causes an interrupt IFF IRQ line is
         * asserted.  IRQ generally should not be asserted when a driver
         * enables their IRQ. It can lead to "interesting" race conditions
         * in the driver initialization sequence.
         */
        DBG(KERN_DEBUG "enable_irq(%d): eoi(%p, 0x%x)\n", irq,
                        vi->eoi_addr, vi->eoi_data);
        iosapic_eoi(vi->eoi_addr, vi->eoi_data);
}

/*
 * PARISC only supports PCI devices below I/O SAPIC.
 * PCI only supports level triggered in order to share IRQ lines.
 * ergo I/O SAPIC must always issue EOI on parisc.
 *
 * i386/ia64 support ISA devices and have to deal with
 * edge-triggered interrupts too.
 */
static void iosapic_end_irq(unsigned int irq)
{
        struct vector_info *vi = iosapic_get_vector(irq);
        DBG(KERN_DEBUG "end_irq(%d): eoi(%p, 0x%x)\n", irq,
                        vi->eoi_addr, vi->eoi_data);
        iosapic_eoi(vi->eoi_addr, vi->eoi_data);
        cpu_end_irq(irq);
}

static unsigned int iosapic_startup_irq(unsigned int irq)
{
        iosapic_enable_irq(irq);
        return 0;
}

#ifdef CONFIG_SMP
static void iosapic_set_affinity_irq(unsigned int irq,
                                     const struct cpumask *dest)
{
        struct vector_info *vi = iosapic_get_vector(irq);
        u32 d0, d1, dummy_d0;
        unsigned long flags;
        int dest_cpu;

        dest_cpu = cpu_check_affinity(irq, dest);
        if (dest_cpu < 0)
                return;

        cpumask_copy(irq_desc[irq].affinity, cpumask_of(dest_cpu));
        vi->txn_addr = txn_affinity_addr(irq, dest_cpu);

        spin_lock_irqsave(&iosapic_lock, flags);
        /* d1 contains the destination CPU, so only want to set that
         * entry */
        iosapic_rd_irt_entry(vi, &d0, &d1);
        iosapic_set_irt_data(vi, &dummy_d0, &d1);
        iosapic_wr_irt_entry(vi, d0, d1);
        spin_unlock_irqrestore(&iosapic_lock, flags);
}
#endif

static struct hw_interrupt_type iosapic_interrupt_type = {
        .typename =     "IO-SAPIC-level",
        .startup =      iosapic_startup_irq,
        .shutdown =     iosapic_disable_irq,
        .enable =       iosapic_enable_irq,
        .disable =      iosapic_disable_irq,
        .ack =          cpu_ack_irq,
        .end =          iosapic_end_irq,
#ifdef CONFIG_SMP
        .set_affinity = iosapic_set_affinity_irq,
#endif
};

int iosapic_fixup_irq(void *isi_obj, struct pci_dev *pcidev)
{
        struct iosapic_info *isi = isi_obj;
        struct irt_entry *irte = NULL;  /* only used if PAT PDC */
        struct vector_info *vi;
        int isi_line;   /* line used by device */

        if (!isi) {
                printk(KERN_WARNING MODULE_NAME ": hpa not registered for %s\n",
                        pci_name(pcidev));
                return -1;
        }

#ifdef CONFIG_SUPERIO
        /*
         * HACK ALERT! (non-compliant PCI device support)
         *
         * All SuckyIO interrupts are routed through the PIC's on function 1.
         * But SuckyIO OHCI USB controller gets an IRT entry anyway because
         * it advertises INT D for INT_PIN.  Use that IRT entry to get the
         * SuckyIO interrupt routing for PICs on function 1 (*BLEECCHH*).
         */
        if (is_superio_device(pcidev)) {
                /* We must call superio_fixup_irq() to register the pdev */
                pcidev->irq = superio_fixup_irq(pcidev);

                /* Don't return if need to program the IOSAPIC's IRT... */
                if (PCI_FUNC(pcidev->devfn) != SUPERIO_USB_FN)
                        return pcidev->irq;
        }
#endif /* CONFIG_SUPERIO */

        /* lookup IRT entry for isi/slot/pin set */
        irte = iosapic_xlate_pin(isi, pcidev);
        if (!irte) {
                printk("iosapic: no IRTE for %s (IRQ not connected?)\n",
                                pci_name(pcidev));
                return -1;
        }
        DBG_IRT("iosapic_fixup_irq(): irte %p %x %x %x %x %x %x %x %x\n",
                irte,
                irte->entry_type,
                irte->entry_length,
                irte->polarity_trigger,
                irte->src_bus_irq_devno,
                irte->src_bus_id,
                irte->src_seg_id,
                irte->dest_iosapic_intin,
                (u32) irte->dest_iosapic_addr);
        isi_line = irte->dest_iosapic_intin;

        /* get vector info for this input line */
        vi = isi->isi_vector + isi_line;
        DBG_IRT("iosapic_fixup_irq:  line %d vi 0x%p\n", isi_line, vi);

        /* If this IRQ line has already been setup, skip it */
        if (vi->irte)
                goto out;

        vi->irte = irte;

        /*
         * Allocate processor IRQ
         *
         * XXX/FIXME The txn_alloc_irq() code and related code should be
         * moved to enable_irq(). That way we only allocate processor IRQ
         * bits for devices that actually have drivers claiming them.
         * Right now we assign an IRQ to every PCI device present,
         * regardless of whether it's used or not.
         */
        vi->txn_irq = txn_alloc_irq(8);

        if (vi->txn_irq < 0)
                panic("I/O sapic: couldn't get TXN IRQ\n");

        /* enable_irq() will use txn_* to program IRdT */
        vi->txn_addr = txn_alloc_addr(vi->txn_irq);
        vi->txn_data = txn_alloc_data(vi->txn_irq);

        vi->eoi_addr = isi->addr + IOSAPIC_REG_EOI;
        vi->eoi_data = cpu_to_le32(vi->txn_data);

        cpu_claim_irq(vi->txn_irq, &iosapic_interrupt_type, vi);

 out:
        pcidev->irq = vi->txn_irq;

        DBG_IRT("iosapic_fixup_irq() %d:%d %x %x line %d irq %d\n",
                PCI_SLOT(pcidev->devfn), PCI_FUNC(pcidev->devfn),
                pcidev->vendor, pcidev->device, isi_line, pcidev->irq);

        return pcidev->irq;
}


/*
** squirrel away the I/O Sapic Version
*/
static unsigned int
iosapic_rd_version(struct iosapic_info *isi)
{
        return iosapic_read(isi->addr, IOSAPIC_REG_VERSION);
}


/*
** iosapic_register() is called by "drivers" with an integrated I/O SAPIC.
** Caller must be certain they have an I/O SAPIC and know its MMIO address.
**
**      o allocate iosapic_info and add it to the list
**      o read iosapic version and squirrel that away
**      o read size of IRdT.
**      o allocate and initialize isi_vector[]
**      o allocate irq region
*/
void *iosapic_register(unsigned long hpa)
{
        struct iosapic_info *isi = NULL;
        struct irt_entry *irte = irt_cell;
        struct vector_info *vip;
        int cnt;        /* track how many entries we've looked at */

        /*
         * Astro based platforms can only support PCI OLARD if they implement
         * PAT PDC.  Legacy PDC omits LBAs with no PCI devices from the IRT.
         * Search the IRT and ignore iosapic's which aren't in the IRT.
         */
        for (cnt=0; cnt < irt_num_entry; cnt++, irte++) {
                WARN_ON(IRT_IOSAPIC_TYPE != irte->entry_type);
                if (COMPARE_IRTE_ADDR(irte, hpa))
                        break;
        }

        if (cnt >= irt_num_entry) {
                DBG("iosapic_register() ignoring 0x%lx (NOT FOUND)\n", hpa);
                return NULL;
        }

        isi = kzalloc(sizeof(struct iosapic_info), GFP_KERNEL);
        if (!isi) {
                BUG();
                return NULL;
        }

        isi->addr = ioremap_nocache(hpa, 4096);
        isi->isi_hpa = hpa;
        isi->isi_version = iosapic_rd_version(isi);
        isi->isi_num_vectors = IOSAPIC_IRDT_MAX_ENTRY(isi->isi_version) + 1;

        vip = isi->isi_vector = (struct vector_info *)
                kzalloc(sizeof(struct vector_info) * isi->isi_num_vectors, GFP_KERNEL);
        if (vip == NULL) {
                kfree(isi);
                return NULL;
        }

        for (cnt=0; cnt < isi->isi_num_vectors; cnt++, vip++) {
                vip->irqline = (unsigned char) cnt;
                vip->iosapic = isi;
        }
        return isi;
}


#ifdef DEBUG_IOSAPIC

static void
iosapic_prt_irt(void *irt, long num_entry)
{
        unsigned int i, *irp = (unsigned int *) irt;


        printk(KERN_DEBUG MODULE_NAME ": Interrupt Routing Table (%lx entries)\n", num_entry);

        for (i=0; i<num_entry; i++, irp += 4) {
                printk(KERN_DEBUG "%p : %2d %.8x %.8x %.8x %.8x\n",
                                        irp, i, irp[0], irp[1], irp[2], irp[3]);
        }
}


static void
iosapic_prt_vi(struct vector_info *vi)
{
        printk(KERN_DEBUG MODULE_NAME ": vector_info[%d] is at %p\n", vi->irqline, vi);
        printk(KERN_DEBUG "\t\tstatus:   %.4x\n", vi->status);
        printk(KERN_DEBUG "\t\ttxn_irq:  %d\n",  vi->txn_irq);
        printk(KERN_DEBUG "\t\ttxn_addr: %lx\n", vi->txn_addr);
        printk(KERN_DEBUG "\t\ttxn_data: %lx\n", vi->txn_data);
        printk(KERN_DEBUG "\t\teoi_addr: %p\n",  vi->eoi_addr);
        printk(KERN_DEBUG "\t\teoi_data: %x\n",  vi->eoi_data);
}


static void
iosapic_prt_isi(struct iosapic_info *isi)
{
        printk(KERN_DEBUG MODULE_NAME ": io_sapic_info at %p\n", isi);
        printk(KERN_DEBUG "\t\tisi_hpa:       %lx\n", isi->isi_hpa);
        printk(KERN_DEBUG "\t\tisi_status:    %x\n", isi->isi_status);
        printk(KERN_DEBUG "\t\tisi_version:   %x\n", isi->isi_version);
        printk(KERN_DEBUG "\t\tisi_vector:    %p\n", isi->isi_vector);
}
#endif /* DEBUG_IOSAPIC */