drivers.c

一个2.4.21版本的嵌入式linux内核

/*
 * 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 <[e-mail]>
 * 
 * The file handles registering devices and drivers, then matching them.
 * It's the closest we get to a dating agency.
 */

#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 <asm/hardware.h>
#include <asm/io.h>
#include <asm/pdc.h>
#include <asm/gsc.h>

/* See comments in include/asm-parisc/pci.h */
struct pci_dma_ops *hppa_dma_ops;

static struct parisc_driver *pa_drivers;
static struct parisc_device root;

/* This lock protects the pa_drivers list _only_ since all parisc_devices
 * are registered before smp_init() is called.  If you wish to add devices
 * after that, this muct be serialised somehow.  I recommend a semaphore
 * rather than a spinlock since driver ->probe functions are allowed to
 * sleep (for example when allocating memory).
 */
static spinlock_t pa_lock = SPIN_LOCK_UNLOCKED;

#define for_each_padev(dev) \
	for (dev = root.child; dev != NULL; dev = next_dev(dev))

#define check_dev(dev) \
	(dev->id.hw_type != HPHW_FAULTY) ? dev : next_dev(dev)

/**
 * next_dev - enumerates registered devices
 * @dev: the previous device returned from next_dev
 *
 * next_dev does a depth-first search of the tree, returning parents
 * before children.  Returns NULL when there are no more devices.
 */
struct parisc_device *next_dev(struct parisc_device *dev)
{
	if (dev->child) {
		return check_dev(dev->child);
	} else if (dev->sibling) {
		return dev->sibling;
	}

	/* Exhausted tree at this level, time to go up. */
	do {
		dev = dev->parent;
		if (dev && dev->sibling)
			return dev->sibling;
	} while (dev != &root);

	return NULL;
}

/**
 * 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 void claim_device(struct parisc_driver *driver, struct parisc_device *dev)
{
	dev->driver = driver;
	request_mem_region(dev->hpa, 0x1000, driver->name);
}

/**
 * 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)
{
	struct parisc_device *device;

	if (driver->next) {
		printk(KERN_WARNING 
		       "BUG: Skipping previously registered driver: %s\n",
		       driver->name);
		return 1;
	}

	for_each_padev(device) {
		if (device->driver)
			continue;
		if (!match_device(driver, device))
			continue;

		if (driver->probe(device) < 0)
			continue;
		claim_device(driver, device);
	}

	/* Note that the list is in reverse order of registration.  This
	 * may be significant if we ever actually support hotplug and have
	 * multiple drivers capable of claiming the same chip.
	 */

	spin_lock(&pa_lock);
	driver->next = pa_drivers;
	pa_drivers = driver;
	spin_unlock(&pa_lock);

	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 parisc_device *device;
	int cnt = 0;

	for_each_padev(device) {
		if (match_device(driver, device))
			cnt++;
	}

	return cnt;
}



/**
 * 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)
{
	struct parisc_device *dev;

	spin_lock(&pa_lock);

	if (pa_drivers == driver) {
		/* was head of list - update head */
		pa_drivers = driver->next;
	} else {
		struct parisc_driver *prev = pa_drivers;

		while (prev && driver != prev->next) {
			prev = prev->next;
		}

		if (!prev) {
			printk(KERN_WARNING "unregister_parisc_driver: %s wasn't registered\n", driver->name);
		} else {
			/* Drop driver from list */
			prev->next = driver->next;
			driver->next = NULL;
		}

	}

	spin_unlock(&pa_lock);

	for_each_padev(dev) {
		if (dev->driver != driver)
			continue;
		dev->driver = NULL;
		release_mem_region(dev->hpa, 0x1000);
	}

	return 0;
}

static struct parisc_device *find_device_by_addr(unsigned long hpa)
{
	struct parisc_device *dev;
	for_each_padev(dev) {
		if (dev->hpa == hpa)
			return dev;
	}
	return 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 *dev, int type)
{
	while (dev != &root) {
		if (dev->id.hw_type == type)
			return dev;
		dev = dev->parent;
	}

	return NULL;
}

static void
get_node_path(struct parisc_device *dev, struct hardware_path *path)
{
	int i = 5;
	memset(&path->bc, -1, 6);
	while (dev != &root) {
		path->bc[i--] = 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->parent, &path);
	path.mod = dev->hw_path;
	return print_hwpath(&path, output);
}


#if defined(CONFIG_PCI) || defined(CONFIG_ISA)
/**
 * get_pci_node_path - 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 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 *dev, struct hardware_path *path)
{
	struct pci_bus *bus;
	const struct parisc_device *padev;
	int i = 5;

	memset(&path->bc, -1, 6);
	path->mod = PCI_FUNC(dev->devfn);
	path->bc[i--] = PCI_SLOT(dev->devfn);
	for (bus = dev->bus; bus->parent; bus = bus->parent) {
		unsigned int devfn = bus->self->devfn;
		path->bc[i--] = PCI_SLOT(devfn) | (PCI_FUNC(devfn) << 5);
	}

	padev = HBA_DATA(bus->sysdata)->dev;
	while (padev != &root) {
		path->bc[i--] = padev->hw_path;
		padev = padev->parent;
	}