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visws.c

/*
 *    Low-Level PCI Support for SGI Visual Workstation
 *
 *    (c) 1999--2000 Martin Mares <mj@ucw.cz>
 */

#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/init.h>

#include "cobalt.h"
#include "lithium.h"

#include "pci.h"


extern struct pci_raw_ops pci_direct_conf1;

static int pci_visws_enable_irq(struct pci_dev *dev) { return 0; }
static void pci_visws_disable_irq(struct pci_dev *dev) { }

int (*pcibios_enable_irq)(struct pci_dev *dev) = &pci_visws_enable_irq;
void (*pcibios_disable_irq)(struct pci_dev *dev) = &pci_visws_disable_irq;

void __init pcibios_penalize_isa_irq(int irq, int active) {}


unsigned int pci_bus0, pci_bus1;

static inline u8 bridge_swizzle(u8 pin, u8 slot) 
{
      return (((pin - 1) + slot) % 4) + 1;
}

static u8 __init visws_swizzle(struct pci_dev *dev, u8 *pinp)
{
      u8 pin = *pinp;

      while (dev->bus->self) {      /* Move up the chain of bridges. */
            pin = bridge_swizzle(pin, PCI_SLOT(dev->devfn));
            dev = dev->bus->self;
      }
      *pinp = pin;

      return PCI_SLOT(dev->devfn);
}

static int __init visws_map_irq(struct pci_dev *dev, u8 slot, u8 pin)
{
      int irq, bus = dev->bus->number;

      pin--;

      /* Nothing useful at PIIX4 pin 1 */
      if (bus == pci_bus0 && slot == 4 && pin == 0)
            return -1;

      /* PIIX4 USB is on Bus 0, Slot 4, Line 3 */
      if (bus == pci_bus0 && slot == 4 && pin == 3) {
            irq = CO_IRQ(CO_APIC_PIIX4_USB);
            goto out;
      }

      /* First pin spread down 1 APIC entry per slot */
      if (pin == 0) {
            irq = CO_IRQ((bus == pci_bus0 ? CO_APIC_PCIB_BASE0 :
                                    CO_APIC_PCIA_BASE0) + slot);
            goto out;
      }

      /* lines 1,2,3 from any slot is shared in this twirly pattern */
      if (bus == pci_bus1) {
            /* lines 1-3 from devices 0 1 rotate over 2 apic entries */
            irq = CO_IRQ(CO_APIC_PCIA_BASE123 + ((slot + (pin - 1)) % 2));
      } else { /* bus == pci_bus0 */
            /* lines 1-3 from devices 0-3 rotate over 3 apic entries */
            if (slot == 0)
                  slot = 3; /* same pattern */
            irq = CO_IRQ(CO_APIC_PCIA_BASE123 + ((3 - slot) + (pin - 1) % 3));
      }
out:
      printk(KERN_DEBUG "PCI: Bus %d Slot %d Line %d -> IRQ %d\n", bus, slot, pin, irq);
      return irq;
}

void __init pcibios_update_irq(struct pci_dev *dev, int irq)
{
      pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq);
}

static int __init pcibios_init(void)
{
      /* The VISWS supports configuration access type 1 only */
      pci_probe = (pci_probe | PCI_PROBE_CONF1) &
                ~(PCI_PROBE_BIOS | PCI_PROBE_CONF2);

      pci_bus0 = li_pcib_read16(LI_PCI_BUSNUM) & 0xff;
      pci_bus1 = li_pcia_read16(LI_PCI_BUSNUM) & 0xff;

      printk(KERN_INFO "PCI: Lithium bridge A bus: %u, "
            "bridge B (PIIX4) bus: %u\n", pci_bus1, pci_bus0);

      raw_pci_ops = &pci_direct_conf1;
      pci_scan_bus_with_sysdata(pci_bus0);
      pci_scan_bus_with_sysdata(pci_bus1);
      pci_fixup_irqs(visws_swizzle, visws_map_irq);
      pcibios_resource_survey();
      return 0;
}

subsys_initcall(pcibios_init);

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