Merge branches 'pm-sleep' and 'pm-cpufreq'

[deliverable/linux.git] / arch / parisc / kernel / drivers.c

/*
 * drivers.c
 *
 * 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.
 *
 * Copyright (c) 1999 The Puffin Group
 * Copyright (c) 2001 Matthew Wilcox for Hewlett Packard
 * Copyright (c) 2001 Helge Deller <deller@gmx.de>
 * Copyright (c) 2001,2002 Ryan Bradetich 
 * Copyright (c) 2004-2005 Thibaut VARENE <varenet@parisc-linux.org>
 * 
 * The file handles registering devices and drivers, then matching them.
 * It's the closest we get to a dating agency.
 *
 * If you're thinking about modifying this file, here are some gotchas to
 * bear in mind:
 *  - 715/Mirage device paths have a dummy device between Lasi and its children
 *  - The EISA adapter may show up as a sibling or child of Wax
 *  - Dino has an optionally functional serial port.  If firmware enables it,
 *    it shows up as a child of Dino.  If firmware disables it, the buswalk
 *    finds it and it shows up as a child of Cujo
 *  - Dino has both parisc and pci devices as children
 *  - parisc devices are discovered in a random order, including children
 *    before parents in some cases.
 */

#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/export.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/pdc.h>
#include <asm/parisc-device.h>

/* See comments in include/asm-parisc/pci.h */
struct dma_map_ops *hppa_dma_ops __read_mostly;
EXPORT_SYMBOL(hppa_dma_ops);

static struct device root = {
        .init_name = "parisc",
};

static inline int check_dev(struct device *dev)
{
        if (dev->bus == &parisc_bus_type) {
                struct parisc_device *pdev;
                pdev = to_parisc_device(dev);
                return pdev->id.hw_type != HPHW_FAULTY;
        }
        return 1;
}

static struct device *
parse_tree_node(struct device *parent, int index, struct hardware_path *modpath);

struct recurse_struct {
        void * obj;
        int (*fn)(struct device *, void *);
};

static int descend_children(struct device * dev, void * data)
{
        struct recurse_struct * recurse_data = (struct recurse_struct *)data;

        if (recurse_data->fn(dev, recurse_data->obj))
                return 1;
        else
                return device_for_each_child(dev, recurse_data, descend_children);
}

/**
 *      for_each_padev - Iterate over all devices in the tree
 *      @fn:    Function to call for each device.
 *      @data:  Data to pass to the called function.
 *
 *      This performs a depth-first traversal of the tree, calling the
 *      function passed for each node.  It calls the function for parents
 *      before children.
 */

static int for_each_padev(int (*fn)(struct device *, void *), void * data)
{
        struct recurse_struct recurse_data = {
                .obj    = data,
                .fn     = fn,
        };
        return device_for_each_child(&root, &recurse_data, descend_children);
}

/**
 * match_device - Report whether this driver can handle this device
 * @driver: the PA-RISC driver to try
 * @dev: the PA-RISC device to try
 */
static int match_device(struct parisc_driver *driver, struct parisc_device *dev)
{
        const struct parisc_device_id *ids;

        for (ids = driver->id_table; ids->sversion; ids++) {
                if ((ids->sversion != SVERSION_ANY_ID) &&
                    (ids->sversion != dev->id.sversion))
                        continue;

                if ((ids->hw_type != HWTYPE_ANY_ID) &&
                    (ids->hw_type != dev->id.hw_type))
                        continue;

                if ((ids->hversion != HVERSION_ANY_ID) &&
                    (ids->hversion != dev->id.hversion))
                        continue;

                return 1;
        }
        return 0;
}

static int parisc_driver_probe(struct device *dev)
{
        int rc;
        struct parisc_device *pa_dev = to_parisc_device(dev);
        struct parisc_driver *pa_drv = to_parisc_driver(dev->driver);

        rc = pa_drv->probe(pa_dev);

        if (!rc)
                pa_dev->driver = pa_drv;

        return rc;
}

static int parisc_driver_remove(struct device *dev)
{
        struct parisc_device *pa_dev = to_parisc_device(dev);
        struct parisc_driver *pa_drv = to_parisc_driver(dev->driver);
        if (pa_drv->remove)
                pa_drv->remove(pa_dev);

        return 0;
}
        

/**
 * register_parisc_driver - Register this driver if it can handle a device
 * @driver: the PA-RISC driver to try
 */
int register_parisc_driver(struct parisc_driver *driver)
{
        /* FIXME: we need this because apparently the sti
         * driver can be registered twice */
        if(driver->drv.name) {
                printk(KERN_WARNING 
                       "BUG: skipping previously registered driver %s\n",
                       driver->name);
                return 1;
        }

        if (!driver->probe) {
                printk(KERN_WARNING 
                       "BUG: driver %s has no probe routine\n",
                       driver->name);
                return 1;
        }

        driver->drv.bus = &parisc_bus_type;

        /* We install our own probe and remove routines */
        WARN_ON(driver->drv.probe != NULL);
        WARN_ON(driver->drv.remove != NULL);

        driver->drv.name = driver->name;

        return driver_register(&driver->drv);
}
EXPORT_SYMBOL(register_parisc_driver);


struct match_count {
        struct parisc_driver * driver;
        int count;
};

static int match_and_count(struct device * dev, void * data)
{
        struct match_count * m = data;
        struct parisc_device * pdev = to_parisc_device(dev);

        if (check_dev(dev)) {
                if (match_device(m->driver, pdev))
                        m->count++;
        }
        return 0;
}

/**
 * count_parisc_driver - count # of devices this driver would match
 * @driver: the PA-RISC driver to try
 *
 * Use by IOMMU support to "guess" the right size IOPdir.
 * Formula is something like memsize/(num_iommu * entry_size).
 */
int count_parisc_driver(struct parisc_driver *driver)
{
        struct match_count m = {
                .driver = driver,
                .count  = 0,
        };

        for_each_padev(match_and_count, &m);

        return m.count;
}



/**
 * unregister_parisc_driver - Unregister this driver from the list of drivers
 * @driver: the PA-RISC driver to unregister
 */
int unregister_parisc_driver(struct parisc_driver *driver)
{
        driver_unregister(&driver->drv);
        return 0;
}
EXPORT_SYMBOL(unregister_parisc_driver);

struct find_data {
        unsigned long hpa;
        struct parisc_device * dev;
};

static int find_device(struct device * dev, void * data)
{
        struct parisc_device * pdev = to_parisc_device(dev);
        struct find_data * d = (struct find_data*)data;

        if (check_dev(dev)) {
                if (pdev->hpa.start == d->hpa) {
                        d->dev = pdev;
                        return 1;
                }
        }
        return 0;
}

static struct parisc_device *find_device_by_addr(unsigned long hpa)
{
        struct find_data d = {
                .hpa    = hpa,
        };
        int ret;

        ret = for_each_padev(find_device, &d);
        return ret ? d.dev : NULL;
}

/**
 * find_pa_parent_type - Find a parent of a specific type
 * @dev: The device to start searching from
 * @type: The device type to search for.
 *
 * Walks up the device tree looking for a device of the specified type.
 * If it finds it, it returns it.  If not, it returns NULL.
 */
const struct parisc_device *
find_pa_parent_type(const struct parisc_device *padev, int type)
{
        const struct device *dev = &padev->dev;
        while (dev != &root) {
                struct parisc_device *candidate = to_parisc_device(dev);
                if (candidate->id.hw_type == type)
                        return candidate;
                dev = dev->parent;
        }

        return NULL;
}

/*
 * get_node_path fills in @path with the firmware path to the device.
 * Note that if @node is a parisc device, we don't fill in the 'mod' field.
 * This is because both callers pass the parent and fill in the mod
 * themselves.  If @node is a PCI device, we do fill it in, even though this
 * is inconsistent.
 */
static void get_node_path(struct device *dev, struct hardware_path *path)
{
        int i = 5;
        memset(&path->bc, -1, 6);

        if (dev_is_pci(dev)) {
                unsigned int devfn = to_pci_dev(dev)->devfn;
                path->mod = PCI_FUNC(devfn);
                path->bc[i--] = PCI_SLOT(devfn);
                dev = dev->parent;
        }

        while (dev != &root) {
                if (dev_is_pci(dev)) {
                        unsigned int devfn = to_pci_dev(dev)->devfn;
                        path->bc[i--] = PCI_SLOT(devfn) | (PCI_FUNC(devfn)<< 5);
                } else if (dev->bus == &parisc_bus_type) {
                        path->bc[i--] = to_parisc_device(dev)->hw_path;
                }
                dev = dev->parent;
        }
}

static char *print_hwpath(struct hardware_path *path, char *output)
{
        int i;
        for (i = 0; i < 6; i++) {
                if (path->bc[i] == -1)
                        continue;
                output += sprintf(output, "%u/", (unsigned char) path->bc[i]);
        }
        output += sprintf(output, "%u", (unsigned char) path->mod);
        return output;
}

/**
 * print_pa_hwpath - Returns hardware path for PA devices
 * dev: The device to return the path for
 * output: Pointer to a previously-allocated array to place the path in.
 *
 * This function fills in the output array with a human-readable path
 * to a PA device.  This string is compatible with that used by PDC, and
 * may be printed on the outside of the box.
 */
char *print_pa_hwpath(struct parisc_device *dev, char *output)
{
        struct hardware_path path;

        get_node_path(dev->dev.parent, &path);
        path.mod = dev->hw_path;
        return print_hwpath(&path, output);
}
EXPORT_SYMBOL(print_pa_hwpath);

#if defined(CONFIG_PCI) || defined(CONFIG_ISA)
/**
 * get_pci_node_path - Determines the hardware path for a PCI device
 * @pdev: The device to return the path for
 * @path: Pointer to a previously-allocated array to place the path in.
 *
 * This function fills in the hardware_path structure with the route to
 * the specified PCI device.  This structure is suitable for passing to
 * PDC calls.
 */
void get_pci_node_path(struct pci_dev *pdev, struct hardware_path *path)
{
        get_node_path(&pdev->dev, path);
}
EXPORT_SYMBOL(get_pci_node_path);

/**
 * print_pci_hwpath - Returns hardware path for PCI devices
 * dev: The device to return the path for
 * output: Pointer to a previously-allocated array to place the path in.
 *
 * This function fills in the output array with a human-readable path
 * to a PCI device.  This string is compatible with that used by PDC, and
 * may be printed on the outside of the box.
 */
char *print_pci_hwpath(struct pci_dev *dev, char *output)
{
        struct hardware_path path;

        get_pci_node_path(dev, &path);
        return print_hwpath(&path, output);
}
EXPORT_SYMBOL(print_pci_hwpath);

#endif /* defined(CONFIG_PCI) || defined(CONFIG_ISA) */

static void setup_bus_id(struct parisc_device *padev)
{
        struct hardware_path path;
        char name[28];
        char *output = name;
        int i;

        get_node_path(padev->dev.parent, &path);

        for (i = 0; i < 6; i++) {
                if (path.bc[i] == -1)
                        continue;
                output += sprintf(output, "%u:", (unsigned char) path.bc[i]);
        }
        sprintf(output, "%u", (unsigned char) padev->hw_path);
        dev_set_name(&padev->dev, name);
}

struct parisc_device * create_tree_node(char id, struct device *parent)
{
        struct parisc_device *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return NULL;

        dev->hw_path = id;
        dev->id.hw_type = HPHW_FAULTY;

        dev->dev.parent = parent;
        setup_bus_id(dev);

        dev->dev.bus = &parisc_bus_type;
        dev->dma_mask = 0xffffffffUL;   /* PARISC devices are 32-bit */

        /* make the generic dma mask a pointer to the parisc one */
        dev->dev.dma_mask = &dev->dma_mask;
        dev->dev.coherent_dma_mask = dev->dma_mask;
        if (device_register(&dev->dev)) {
                kfree(dev);
                return NULL;
        }

        return dev;
}

struct match_id_data {
        char id;
        struct parisc_device * dev;
};

static int match_by_id(struct device * dev, void * data)
{
        struct parisc_device * pdev = to_parisc_device(dev);
        struct match_id_data * d = data;

        if (pdev->hw_path == d->id) {
                d->dev = pdev;
                return 1;
        }
        return 0;
}

/**
 * alloc_tree_node - returns a device entry in the iotree
 * @parent: the parent node in the tree
 * @id: the element of the module path for this entry
 *
 * Checks all the children of @parent for a matching @id.  If none
 * found, it allocates a new device and returns it.
 */
static struct parisc_device * alloc_tree_node(struct device *parent, char id)
{
        struct match_id_data d = {
                .id = id,
        };
        if (device_for_each_child(parent, &d, match_by_id))
                return d.dev;
        else
                return create_tree_node(id, parent);
}

static struct parisc_device *create_parisc_device(struct hardware_path *modpath)
{
        int i;
        struct device *parent = &root;
        for (i = 0; i < 6; i++) {
                if (modpath->bc[i] == -1)
                        continue;
                parent = &alloc_tree_node(parent, modpath->bc[i])->dev;
        }
        return alloc_tree_node(parent, modpath->mod);
}

struct parisc_device *
alloc_pa_dev(unsigned long hpa, struct hardware_path *mod_path)
{
        int status;
        unsigned long bytecnt;
        u8 iodc_data[32];
        struct parisc_device *dev;
        const char *name;

        /* Check to make sure this device has not already been added - Ryan */
        if (find_device_by_addr(hpa) != NULL)
                return NULL;

        status = pdc_iodc_read(&bytecnt, hpa, 0, &iodc_data, 32);
        if (status != PDC_OK)
                return NULL;

        dev = create_parisc_device(mod_path);
        if (dev->id.hw_type != HPHW_FAULTY) {
                printk(KERN_ERR "Two devices have hardware path [%s].  "
                                "IODC data for second device: "
                                "%02x%02x%02x%02x%02x%02x\n"
                                "Rearranging GSC cards sometimes helps\n",
                        parisc_pathname(dev), iodc_data[0], iodc_data[1],
                        iodc_data[3], iodc_data[4], iodc_data[5], iodc_data[6]);
                return NULL;
        }

        dev->id.hw_type = iodc_data[3] & 0x1f;
        dev->id.hversion = (iodc_data[0] << 4) | ((iodc_data[1] & 0xf0) >> 4);
        dev->id.hversion_rev = iodc_data[1] & 0x0f;
        dev->id.sversion = ((iodc_data[4] & 0x0f) << 16) |
                        (iodc_data[5] << 8) | iodc_data[6];
        dev->hpa.name = parisc_pathname(dev);
        dev->hpa.start = hpa;
        /* This is awkward.  The STI spec says that gfx devices may occupy
         * 32MB or 64MB.  Unfortunately, we don't know how to tell whether
         * it's the former or the latter.  Assumptions either way can hurt us.
         */
        if (hpa == 0xf4000000 || hpa == 0xf8000000) {
                dev->hpa.end = hpa + 0x03ffffff;
        } else if (hpa == 0xf6000000 || hpa == 0xfa000000) {
                dev->hpa.end = hpa + 0x01ffffff;
        } else {
                dev->hpa.end = hpa + 0xfff;
        }
        dev->hpa.flags = IORESOURCE_MEM;
        name = parisc_hardware_description(&dev->id);
        if (name) {
                strlcpy(dev->name, name, sizeof(dev->name));
        }

        /* Silently fail things like mouse ports which are subsumed within
         * the keyboard controller
         */
        if ((hpa & 0xfff) == 0 && insert_resource(&iomem_resource, &dev->hpa))
                printk("Unable to claim HPA %lx for device %s\n",
                                hpa, name);

        return dev;
}

static int parisc_generic_match(struct device *dev, struct device_driver *drv)
{
        return match_device(to_parisc_driver(drv), to_parisc_device(dev));
}

static ssize_t make_modalias(struct device *dev, char *buf)
{
        const struct parisc_device *padev = to_parisc_device(dev);
        const struct parisc_device_id *id = &padev->id;

        return sprintf(buf, "parisc:t%02Xhv%04Xrev%02Xsv%08X\n",
                (u8)id->hw_type, (u16)id->hversion, (u8)id->hversion_rev,
                (u32)id->sversion);
}

static int parisc_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        const struct parisc_device *padev;
        char modalias[40];

        if (!dev)
                return -ENODEV;

        padev = to_parisc_device(dev);
        if (!padev)
                return -ENODEV;

        if (add_uevent_var(env, "PARISC_NAME=%s", padev->name))
                return -ENOMEM;

        make_modalias(dev, modalias);
        if (add_uevent_var(env, "MODALIAS=%s", modalias))
                return -ENOMEM;

        return 0;
}

#define pa_dev_attr(name, field, format_string)                         \
static ssize_t name##_show(struct device *dev, struct device_attribute *attr, char *buf)                \
{                                                                       \
        struct parisc_device *padev = to_parisc_device(dev);            \
        return sprintf(buf, format_string, padev->field);               \
}

#define pa_dev_attr_id(field, format) pa_dev_attr(field, id.field, format)

pa_dev_attr(irq, irq, "%u\n");
pa_dev_attr_id(hw_type, "0x%02x\n");
pa_dev_attr(rev, id.hversion_rev, "0x%x\n");
pa_dev_attr_id(hversion, "0x%03x\n");
pa_dev_attr_id(sversion, "0x%05x\n");

static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        return make_modalias(dev, buf);
}

static struct device_attribute parisc_device_attrs[] = {
        __ATTR_RO(irq),
        __ATTR_RO(hw_type),
        __ATTR_RO(rev),
        __ATTR_RO(hversion),
        __ATTR_RO(sversion),
        __ATTR_RO(modalias),
        __ATTR_NULL,
};

struct bus_type parisc_bus_type = {
        .name = "parisc",
        .match = parisc_generic_match,
        .uevent = parisc_uevent,
        .dev_attrs = parisc_device_attrs,
        .probe = parisc_driver_probe,
        .remove = parisc_driver_remove,
};

/**
 * register_parisc_device - Locate a driver to manage this device.
 * @dev: The parisc device.
 *
 * Search the driver list for a driver that is willing to manage
 * this device.
 */
int register_parisc_device(struct parisc_device *dev)
{
        if (!dev)
                return 0;

        if (dev->driver)
                return 1;

        return 0;
}

/**
 * match_pci_device - Matches a pci device against a given hardware path
 * entry.
 * @dev: the generic device (known to be contained by a pci_dev).
 * @index: the current BC index
 * @modpath: the hardware path.
 * @return: true if the device matches the hardware path.
 */
static int match_pci_device(struct device *dev, int index,
                struct hardware_path *modpath)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        int id;

        if (index == 5) {
                /* we are at the end of the path, and on the actual device */
                unsigned int devfn = pdev->devfn;
                return ((modpath->bc[5] == PCI_SLOT(devfn)) &&
                                        (modpath->mod == PCI_FUNC(devfn)));
        }

        id = PCI_SLOT(pdev->devfn) | (PCI_FUNC(pdev->devfn) << 5);
        return (modpath->bc[index] == id);
}

/**
 * match_parisc_device - Matches a parisc device against a given hardware
 * path entry.
 * @dev: the generic device (known to be contained by a parisc_device).
 * @index: the current BC index
 * @modpath: the hardware path.
 * @return: true if the device matches the hardware path.
 */
static int match_parisc_device(struct device *dev, int index,
                struct hardware_path *modpath)
{
        struct parisc_device *curr = to_parisc_device(dev);
        char id = (index == 6) ? modpath->mod : modpath->bc[index];

        return (curr->hw_path == id);
}

struct parse_tree_data {
        int index;
        struct hardware_path * modpath;
        struct device * dev;
};

static int check_parent(struct device * dev, void * data)
{
        struct parse_tree_data * d = data;

        if (check_dev(dev)) {
                if (dev->bus == &parisc_bus_type) {
                        if (match_parisc_device(dev, d->index, d->modpath))
                                d->dev = dev;
                } else if (dev_is_pci(dev)) {
                        if (match_pci_device(dev, d->index, d->modpath))
                                d->dev = dev;
                } else if (dev->bus == NULL) {
                        /* we are on a bus bridge */
                        struct device *new = parse_tree_node(dev, d->index, d->modpath);
                        if (new)
                                d->dev = new;
                }
        }
        return d->dev != NULL;
}

/**
 * parse_tree_node - returns a device entry in the iotree
 * @parent: the parent node in the tree
 * @index: the current BC index
 * @modpath: the hardware_path struct to match a device against
 * @return: The corresponding device if found, NULL otherwise.
 *
 * Checks all the children of @parent for a matching @id.  If none
 * found, it returns NULL.
 */
static struct device *
parse_tree_node(struct device *parent, int index, struct hardware_path *modpath)
{
        struct parse_tree_data d = {
                .index          = index,
                .modpath        = modpath,
        };

        struct recurse_struct recurse_data = {
                .obj    = &d,
                .fn     = check_parent,
        };

        if (device_for_each_child(parent, &recurse_data, descend_children))
                /* nothing */;

        return d.dev;
}

/**
 * hwpath_to_device - Finds the generic device corresponding to a given hardware path.
 * @modpath: the hardware path.
 * @return: The target device, NULL if not found.
 */
struct device *hwpath_to_device(struct hardware_path *modpath)
{
        int i;
        struct device *parent = &root;
        for (i = 0; i < 6; i++) {
                if (modpath->bc[i] == -1)
                        continue;
                parent = parse_tree_node(parent, i, modpath);
                if (!parent)
                        return NULL;
        }
        if (dev_is_pci(parent)) /* pci devices already parse MOD */
                return parent;
        else
                return parse_tree_node(parent, 6, modpath);
}
EXPORT_SYMBOL(hwpath_to_device);

/**
 * device_to_hwpath - Populates the hwpath corresponding to the given device.
 * @param dev the target device
 * @param path pointer to a previously allocated hwpath struct to be filled in
 */
void device_to_hwpath(struct device *dev, struct hardware_path *path)
{
        struct parisc_device *padev;
        if (dev->bus == &parisc_bus_type) {
                padev = to_parisc_device(dev);
                get_node_path(dev->parent, path);
                path->mod = padev->hw_path;
        } else if (dev_is_pci(dev)) {
                get_node_path(dev, path);
        }
}
EXPORT_SYMBOL(device_to_hwpath);

#define BC_PORT_MASK 0x8
#define BC_LOWER_PORT 0x8

#define BUS_CONVERTER(dev) \
        ((dev->id.hw_type == HPHW_IOA) || (dev->id.hw_type == HPHW_BCPORT))

#define IS_LOWER_PORT(dev) \
        ((gsc_readl(dev->hpa.start + offsetof(struct bc_module, io_status)) \
                & BC_PORT_MASK) == BC_LOWER_PORT)

#define MAX_NATIVE_DEVICES 64
#define NATIVE_DEVICE_OFFSET 0x1000

#define FLEX_MASK       F_EXTEND(0xfffc0000)
#define IO_IO_LOW       offsetof(struct bc_module, io_io_low)
#define IO_IO_HIGH      offsetof(struct bc_module, io_io_high)
#define READ_IO_IO_LOW(dev)  (unsigned long)(signed int)gsc_readl(dev->hpa.start + IO_IO_LOW)
#define READ_IO_IO_HIGH(dev) (unsigned long)(signed int)gsc_readl(dev->hpa.start + IO_IO_HIGH)

static void walk_native_bus(unsigned long io_io_low, unsigned long io_io_high,
                            struct device *parent);

void walk_lower_bus(struct parisc_device *dev)
{
        unsigned long io_io_low, io_io_high;

        if (!BUS_CONVERTER(dev) || IS_LOWER_PORT(dev))
                return;

        if (dev->id.hw_type == HPHW_IOA) {
                io_io_low = (unsigned long)(signed int)(READ_IO_IO_LOW(dev) << 16);
                io_io_high = io_io_low + MAX_NATIVE_DEVICES * NATIVE_DEVICE_OFFSET;
        } else {
                io_io_low = (READ_IO_IO_LOW(dev) + ~FLEX_MASK) & FLEX_MASK;
                io_io_high = (READ_IO_IO_HIGH(dev)+ ~FLEX_MASK) & FLEX_MASK;
        }

        walk_native_bus(io_io_low, io_io_high, &dev->dev);
}

/**
 * walk_native_bus -- Probe a bus for devices
 * @io_io_low: Base address of this bus.
 * @io_io_high: Last address of this bus.
 * @parent: The parent bus device.
 * 
 * A native bus (eg Runway or GSC) may have up to 64 devices on it,
 * spaced at intervals of 0x1000 bytes.  PDC may not inform us of these
 * devices, so we have to probe for them.  Unfortunately, we may find
 * devices which are not physically connected (such as extra serial &
 * keyboard ports).  This problem is not yet solved.
 */
static void walk_native_bus(unsigned long io_io_low, unsigned long io_io_high,
                            struct device *parent)
{
        int i, devices_found = 0;
        unsigned long hpa = io_io_low;
        struct hardware_path path;

        get_node_path(parent, &path);
        do {
                for(i = 0; i < MAX_NATIVE_DEVICES; i++, hpa += NATIVE_DEVICE_OFFSET) {
                        struct parisc_device *dev;

                        /* Was the device already added by Firmware? */
                        dev = find_device_by_addr(hpa);
                        if (!dev) {
                                path.mod = i;
                                dev = alloc_pa_dev(hpa, &path);
                                if (!dev)
                                        continue;

                                register_parisc_device(dev);
                                devices_found++;
                        }
                        walk_lower_bus(dev);
                }
        } while(!devices_found && hpa < io_io_high);
}

#define CENTRAL_BUS_ADDR F_EXTEND(0xfff80000)

/**
 * walk_central_bus - Find devices attached to the central bus
 *
 * PDC doesn't tell us about all devices in the system.  This routine
 * finds devices connected to the central bus.
 */
void walk_central_bus(void)
{
        walk_native_bus(CENTRAL_BUS_ADDR,
                        CENTRAL_BUS_ADDR + (MAX_NATIVE_DEVICES * NATIVE_DEVICE_OFFSET),
                        &root);
}

static void print_parisc_device(struct parisc_device *dev)
{
        char hw_path[64];
        static int count;

        print_pa_hwpath(dev, hw_path);
        printk(KERN_INFO "%d. %s at 0x%p [%s] { %d, 0x%x, 0x%.3x, 0x%.5x }",
                ++count, dev->name, (void*) dev->hpa.start, hw_path, dev->id.hw_type,
                dev->id.hversion_rev, dev->id.hversion, dev->id.sversion);

        if (dev->num_addrs) {
                int k;
                printk(", additional addresses: ");
                for (k = 0; k < dev->num_addrs; k++)
                        printk("0x%lx ", dev->addr[k]);
        }
        printk("\n");
}

/**
 * init_parisc_bus - Some preparation to be done before inventory
 */
void init_parisc_bus(void)
{
        if (bus_register(&parisc_bus_type))
                panic("Could not register PA-RISC bus type\n");
        if (device_register(&root))
                panic("Could not register PA-RISC root device\n");
        get_device(&root);
}


static int print_one_device(struct device * dev, void * data)
{
        struct parisc_device * pdev = to_parisc_device(dev);

        if (check_dev(dev))
                print_parisc_device(pdev);
        return 0;
}

/**
 * print_parisc_devices - Print out a list of devices found in this system
 */
void print_parisc_devices(void)
{
        for_each_padev(print_one_device, NULL);
}