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isa-bridge.c

/*
 * Routines for tracking a legacy ISA bridge
 *
 * Copyrigh 2007 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
 *
 * Some bits and pieces moved over from pci_64.c
 *
 * Copyrigh 2003 Anton Blanchard <anton@au.ibm.com>, IBM Corp.
 *
 *      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.
 */

#define DEBUG

#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/notifier.h>

#include <asm/processor.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/pci-bridge.h>
#include <asm/machdep.h>
#include <asm/ppc-pci.h>
#include <asm/firmware.h>

unsigned long isa_io_base;    /* NULL if no ISA bus */
EXPORT_SYMBOL(isa_io_base);

/* Cached ISA bridge dev. */
static struct device_node *isa_bridge_devnode;
struct pci_dev *isa_bridge_pcidev;
EXPORT_SYMBOL_GPL(isa_bridge_pcidev);

#define ISA_SPACE_MASK 0x1
#define ISA_SPACE_IO 0x1

static void __devinit pci_process_ISA_OF_ranges(struct device_node *isa_node,
                                    unsigned long phb_io_base_phys)
{
      /* We should get some saner parsing here and remove these structs */
      struct pci_address {
            u32 a_hi;
            u32 a_mid;
            u32 a_lo;
      };

      struct isa_address {
            u32 a_hi;
            u32 a_lo;
      };

      struct isa_range {
            struct isa_address isa_addr;
            struct pci_address pci_addr;
            unsigned int size;
      };

      const struct isa_range *range;
      unsigned long pci_addr;
      unsigned int isa_addr;
      unsigned int size;
      int rlen = 0;

      range = of_get_property(isa_node, "ranges", &rlen);
      if (range == NULL || (rlen < sizeof(struct isa_range)))
            goto inval_range;

      /* From "ISA Binding to 1275"
       * The ranges property is laid out as an array of elements,
       * each of which comprises:
       *   cells 0 - 1: an ISA address
       *   cells 2 - 4: a PCI address
       *                (size depending on dev->n_addr_cells)
       *   cell 5:            the size of the range
       */
      if ((range->isa_addr.a_hi & ISA_SPACE_MASK) != ISA_SPACE_IO) {
            range++;
            rlen -= sizeof(struct isa_range);
            if (rlen < sizeof(struct isa_range))
                  goto inval_range;
      }
      if ((range->isa_addr.a_hi & ISA_SPACE_MASK) != ISA_SPACE_IO)
            goto inval_range;

      isa_addr = range->isa_addr.a_lo;
      pci_addr = (unsigned long) range->pci_addr.a_mid << 32 |
            range->pci_addr.a_lo;

      /* Assume these are both zero. Note: We could fix that and
       * do a proper parsing instead ... oh well, that will do for
       * now as nobody uses fancy mappings for ISA bridges
       */
      if ((pci_addr != 0) || (isa_addr != 0)) {
            printk(KERN_ERR "unexpected isa to pci mapping: %s\n",
                   __func__);
            return;
      }

      /* Align size and make sure it's cropped to 64K */
      size = PAGE_ALIGN(range->size);
      if (size > 0x10000)
            size = 0x10000;

      __ioremap_at(phb_io_base_phys, (void *)ISA_IO_BASE,
                 size, _PAGE_NO_CACHE|_PAGE_GUARDED);
      return;

inval_range:
      printk(KERN_ERR "no ISA IO ranges or unexpected isa range, "
             "mapping 64k\n");
      __ioremap_at(phb_io_base_phys, (void *)ISA_IO_BASE,
                 0x10000, _PAGE_NO_CACHE|_PAGE_GUARDED);
}


/**
 * isa_bridge_find_early - Find and map the ISA IO space early before
 *                         main PCI discovery. This is optionally called by
 *                         the arch code when adding PCI PHBs to get early
 *                         access to ISA IO ports
 */
void __init isa_bridge_find_early(struct pci_controller *hose)
{
      struct device_node *np, *parent = NULL, *tmp;

      /* If we already have an ISA bridge, bail off */
      if (isa_bridge_devnode != NULL)
            return;

      /* For each "isa" node in the system. Note : we do a search by
       * type and not by name. It might be better to do by name but that's
       * what the code used to do and I don't want to break too much at
       * once. We can look into changing that separately
       */
      for_each_node_by_type(np, "isa") {
            /* Look for our hose being a parent */
            for (parent = of_get_parent(np); parent;) {
                  if (parent == hose->dn) {
                        of_node_put(parent);
                        break;
                  }
                  tmp = parent;
                  parent = of_get_parent(parent);
                  of_node_put(tmp);
            }
            if (parent != NULL)
                  break;
      }
      if (np == NULL)
            return;
      isa_bridge_devnode = np;

      /* Now parse the "ranges" property and setup the ISA mapping */
      pci_process_ISA_OF_ranges(np, hose->io_base_phys);

      /* Set the global ISA io base to indicate we have an ISA bridge */
      isa_io_base = ISA_IO_BASE;

      pr_debug("ISA bridge (early) is %s\n", np->full_name);
}

/**
 * isa_bridge_find_late - Find and map the ISA IO space upon discovery of
 *                        a new ISA bridge
 */
static void __devinit isa_bridge_find_late(struct pci_dev *pdev,
                                 struct device_node *devnode)
{
      struct pci_controller *hose = pci_bus_to_host(pdev->bus);

      /* Store ISA device node and PCI device */
      isa_bridge_devnode = of_node_get(devnode);
      isa_bridge_pcidev = pdev;

      /* Now parse the "ranges" property and setup the ISA mapping */
      pci_process_ISA_OF_ranges(devnode, hose->io_base_phys);

      /* Set the global ISA io base to indicate we have an ISA bridge */
      isa_io_base = ISA_IO_BASE;

      pr_debug("ISA bridge (late) is %s on %s\n",
             devnode->full_name, pci_name(pdev));
}

/**
 * isa_bridge_remove - Remove/unmap an ISA bridge
 */
static void isa_bridge_remove(void)
{
      pr_debug("ISA bridge removed !\n");

      /* Clear the global ISA io base to indicate that we have no more
       * ISA bridge. Note that drivers don't quite handle that, though
       * we should probably do something about it. But do we ever really
       * have ISA bridges being removed on machines using legacy devices ?
       */
      isa_io_base = ISA_IO_BASE;

      /* Clear references to the bridge */
      of_node_put(isa_bridge_devnode);
      isa_bridge_devnode = NULL;
      isa_bridge_pcidev = NULL;

      /* Unmap the ISA area */
      __iounmap_at((void *)ISA_IO_BASE, 0x10000);
}

/**
 * isa_bridge_notify - Get notified of PCI devices addition/removal
 */
static int __devinit isa_bridge_notify(struct notifier_block *nb,
                               unsigned long action, void *data)
{
      struct device *dev = data;
      struct pci_dev *pdev = to_pci_dev(dev);
      struct device_node *devnode = pci_device_to_OF_node(pdev);

      switch(action) {
      case BUS_NOTIFY_ADD_DEVICE:
            /* Check if we have an early ISA device, without PCI dev */
            if (isa_bridge_devnode && isa_bridge_devnode == devnode &&
                !isa_bridge_pcidev) {
                  pr_debug("ISA bridge PCI attached: %s\n",
                         pci_name(pdev));
                  isa_bridge_pcidev = pdev;
            }

            /* Check if we have no ISA device, and this happens to be one,
             * register it as such if it has an OF device
             */
            if (!isa_bridge_devnode && devnode && devnode->type &&
                !strcmp(devnode->type, "isa"))
                  isa_bridge_find_late(pdev, devnode);

            return 0;
      case BUS_NOTIFY_DEL_DEVICE:
            /* Check if this our existing ISA device */
            if (pdev == isa_bridge_pcidev ||
                (devnode && devnode == isa_bridge_devnode))
                  isa_bridge_remove();
            return 0;
      }
      return 0;
}

static struct notifier_block isa_bridge_notifier = {
      .notifier_call = isa_bridge_notify
};

/**
 * isa_bridge_init - register to be notified of ISA bridge addition/removal
 *
 */
static int __init isa_bridge_init(void)
{
      if (firmware_has_feature(FW_FEATURE_ISERIES))
            return 0;
      bus_register_notifier(&pci_bus_type, &isa_bridge_notifier);
      return 0;
}
arch_initcall(isa_bridge_init);

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