pci.c

讲述linux的初始化过程

/*
 * $Id: pci.c,v 1.64 1999/09/17 18:01:53 cort Exp $
 * Common pmac/prep/chrp pci routines. -- Cort
 */

#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/openpic.h>
#include <linux/capability.h>
#include <linux/sched.h>
#include <linux/errno.h>

#include <asm/processor.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/pci-bridge.h>
#include <asm/residual.h>
#include <asm/byteorder.h>
#include <asm/irq.h>
#include <asm/gg2.h>
#include <asm/uaccess.h>

#include "pci.h"

#undef DEBUG

#ifdef DEBUG
#define DBG(x...) printk(x)
#else
#define DBG(x...)
#endif

unsigned long isa_io_base     = 0;
unsigned long isa_mem_base    = 0;
unsigned long pci_dram_offset = 0;

struct pci_fixup pcibios_fixups[] = {
	{ 0 }
};

int generic_pcibios_read_byte(struct pci_dev *dev, int where, u8 *val)
{
	return ppc_md.pcibios_read_config_byte(dev->bus->number,dev->devfn,where,val);
}
int generic_pcibios_read_word(struct pci_dev *dev, int where, u16 *val)
{
	return ppc_md.pcibios_read_config_word(dev->bus->number,dev->devfn,where,val);
}
int generic_pcibios_read_dword(struct pci_dev *dev, int where, u32 *val)
{
	return ppc_md.pcibios_read_config_dword(dev->bus->number,dev->devfn,where,val);
}
int generic_pcibios_write_byte(struct pci_dev *dev, int where, u8 val)
{
	return ppc_md.pcibios_write_config_byte(dev->bus->number,dev->devfn,where,val);
}
int generic_pcibios_write_word(struct pci_dev *dev, int where, u16 val)
{
	return ppc_md.pcibios_write_config_word(dev->bus->number,dev->devfn,where,val);
}
int generic_pcibios_write_dword(struct pci_dev *dev, int where, u32 val)
{
	return ppc_md.pcibios_write_config_dword(dev->bus->number,dev->devfn,where,val);
}

struct pci_ops generic_pci_ops = 
{
	generic_pcibios_read_byte,
	generic_pcibios_read_word,
	generic_pcibios_read_dword,
	generic_pcibios_write_byte,
	generic_pcibios_write_word,
	generic_pcibios_write_dword
};



void pcibios_update_resource(struct pci_dev *dev, struct resource *root,
			     struct resource *res, int resource)
{
	u32 new, check;
	int reg;

	new = res->start | (res->flags & PCI_REGION_FLAG_MASK);
	if (resource < 6) {
		reg = PCI_BASE_ADDRESS_0 + 4*resource;
	} else if (resource == PCI_ROM_RESOURCE) {
		res->flags |= PCI_ROM_ADDRESS_ENABLE;
		reg = dev->rom_base_reg;
	} else {
		/* Somebody might have asked allocation of a non-standard resource */
		return;
	}

	pci_write_config_dword(dev, reg, new);
	pci_read_config_dword(dev, reg, &check);
	if ((new ^ check) & ((new & PCI_BASE_ADDRESS_SPACE_IO) ? PCI_BASE_ADDRESS_IO_MASK : PCI_BASE_ADDRESS_MEM_MASK)) {
		printk(KERN_ERR "PCI: Error while updating region "
		       "%s/%d (%08x != %08x)\n", dev->slot_name, resource,
		       new, check);
	}
}

/*
 * We need to avoid collisions with `mirrored' VGA ports
 * and other strange ISA hardware, so we always want the
 * addresses to be allocated in the 0x000-0x0ff region
 * modulo 0x400.
 *
 * Why? Because some silly external IO cards only decode
 * the low 10 bits of the IO address. The 0x00-0xff region
 * is reserved for motherboard devices that decode all 16
 * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
 * but we want to try to avoid allocating at 0x2900-0x2bff
 * which might have be mirrored at 0x0100-0x03ff..
 */
void
pcibios_align_resource(void *data, struct resource *res, unsigned long size)
{
	struct pci_dev *dev = data;

	if (res->flags & IORESOURCE_IO) {
		unsigned long start = res->start;

		if (size > 0x100) {
			printk(KERN_ERR "PCI: I/O Region %s/%d too large"
			       " (%ld bytes)\n", dev->slot_name,
			       dev->resource - res, size);
		}

		if (start & 0x300) {
			start = (start + 0x3ff) & ~0x3ff;
			res->start = start;
		}
	}
}


/*
 *  Handle resources of PCI devices.  If the world were perfect, we could
 *  just allocate all the resource regions and do nothing more.  It isn't.
 *  On the other hand, we cannot just re-allocate all devices, as it would
 *  require us to know lots of host bridge internals.  So we attempt to
 *  keep as much of the original configuration as possible, but tweak it
 *  when it's found to be wrong.
 *
 *  Known BIOS problems we have to work around:
 *	- I/O or memory regions not configured
 *	- regions configured, but not enabled in the command register
 *	- bogus I/O addresses above 64K used
 *	- expansion ROMs left enabled (this may sound harmless, but given
 *	  the fact the PCI specs explicitly allow address decoders to be
 *	  shared between expansion ROMs and other resource regions, it's
 *	  at least dangerous)
 *
 *  Our solution:
 *	(1) Allocate resources for all buses behind PCI-to-PCI bridges.
 *	    This gives us fixed barriers on where we can allocate.
 *	(2) Allocate resources for all enabled devices.  If there is
 *	    a collision, just mark the resource as unallocated. Also
 *	    disable expansion ROMs during this step.
 *	(3) Try to allocate resources for disabled devices.  If the
 *	    resources were assigned correctly, everything goes well,
 *	    if they weren't, they won't disturb allocation of other
 *	    resources.
 *	(4) Assign new addresses to resources which were either
 *	    not configured at all or misconfigured.  If explicitly
 *	    requested by the user, configure expansion ROM address
 *	    as well.
 */

static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
{
	struct list_head *ln;
	struct pci_bus *bus;
	struct pci_dev *dev;
	int idx;
	struct resource *r, *pr;

	/* Depth-First Search on bus tree */
	for (ln=bus_list->next; ln != bus_list; ln=ln->next) {
		bus = pci_bus_b(ln);
		if ((dev = bus->self)) {
			for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_NUM_RESOURCES; idx++) {
				r = &dev->resource[idx];
				if (!r->start)
					continue;
				pr = pci_find_parent_resource(dev, r);
				if (!pr || request_resource(pr, r) < 0)
					printk(KERN_ERR "PCI: Cannot allocate resource region %d of bridge %s\n", idx, dev->slot_name);
			}
		}
		pcibios_allocate_bus_resources(&bus->children);
	}
}

static void __init pcibios_allocate_resources(int pass)
{
	struct pci_dev *dev;
	int idx, disabled;
	u16 command;
	struct resource *r, *pr;

	pci_for_each_dev(dev) {
		pci_read_config_word(dev, PCI_COMMAND, &command);
		for(idx = 0; idx < 6; idx++) {
			r = &dev->resource[idx];
			if (r->parent)		/* Already allocated */
				continue;
			if (!r->start)		/* Address not assigned at all */
				continue;
			if (r->end == 0xffffffff) {
				/* LongTrail OF quirk: unassigned */
				DBG("PCI: Resource %08lx-%08lx was unassigned\n", r->start, r->end);
				r->end -= r->start;
				r->start = 0;
				continue;
			}

			if (r->flags & IORESOURCE_IO)
				disabled = !(command & PCI_COMMAND_IO);
			else
				disabled = !(command & PCI_COMMAND_MEMORY);
			if (pass == disabled) {
				DBG("PCI: Resource %08lx-%08lx (f=%lx, d=%d, p=%d)\n",
				    r->start, r->end, r->flags, disabled, pass);
				pr = pci_find_parent_resource(dev, r);
				if (!pr || request_resource(pr, r) < 0) {
					printk(KERN_ERR "PCI: Cannot allocate resource region %d of device %s\n", idx, dev->slot_name);
					/* We'll assign a new address later */
					r->end -= r->start;
					r->start = 0;
				}
			}
		}
		if (!pass) {
			r = &dev->resource[PCI_ROM_RESOURCE];
			if (r->flags & PCI_ROM_ADDRESS_ENABLE) {
				/* Turn the ROM off, leave the resource region, but keep it unregistered. */
				u32 reg;
				DBG("PCI: Switching off ROM of %s\n", dev->slot_name);
				r->flags &= ~PCI_ROM_ADDRESS_ENABLE;
				pci_read_config_dword(dev, dev->rom_base_reg, &reg);
				pci_write_config_dword(dev, dev->rom_base_reg, reg & ~PCI_ROM_ADDRESS_ENABLE);
			}
		}
	}
}

static void __init pcibios_assign_resources(void)
{
	struct pci_dev *dev;
	int idx;
	struct resource *r;

	pci_for_each_dev(dev) {
		int class = dev->class >> 8;

		/* Don't touch classless devices and host bridges */
		if (!class || class == PCI_CLASS_BRIDGE_HOST)
			continue;

		for(idx=0; idx<6; idx++) {
			r = &dev->resource[idx];

			/*
			 *  Don't touch IDE controllers and I/O ports of video cards!
			 */
			if ((class == PCI_CLASS_STORAGE_IDE && idx < 4) ||
			    (class == PCI_CLASS_DISPLAY_VGA && (r->flags & IORESOURCE_IO)))
				continue;

			/*
			 *  We shall assign a new address to this resource, either because
			 *  the BIOS forgot to do so or because we have decided the old
			 *  address was unusable for some reason.
			 */
			if (!r->start && r->end)
				pci_assign_resource(dev, idx);
		}

		if (0) { /* don't assign ROMs */
			r = &dev->resource[PCI_ROM_RESOURCE];
			r->end -= r->start;
			r->start = 0;
			if (r->end)
				pci_assign_resource(dev, PCI_ROM_RESOURCE);
		}
	}
}


int pcibios_enable_resources(struct pci_dev *dev)
{
	u16 cmd, old_cmd;
	int idx;
	struct resource *r;

	pci_read_config_word(dev, PCI_COMMAND, &cmd);
	old_cmd = cmd;
	for(idx=0; idx<6; idx++) {
		r = &dev->resource[idx];
		if (!r->start && r->end) {
			printk(KERN_ERR "PCI: Device %s not available because of resource collisions\n", dev->slot_name);
			return -EINVAL;
		}
		if (r->flags & IORESOURCE_IO)
			cmd |= PCI_COMMAND_IO;
		if (r->flags & IORESOURCE_MEM)
			cmd |= PCI_COMMAND_MEMORY;
	}
	if (dev->resource[PCI_ROM_RESOURCE].start)
		cmd |= PCI_COMMAND_MEMORY;
	if (cmd != old_cmd) {
		printk("PCI: Enabling device %s (%04x -> %04x)\n", dev->slot_name, old_cmd, cmd);
		pci_write_config_word(dev, PCI_COMMAND, cmd);
	}
	return 0;
}



void __init pcibios_init(void)
{
	printk("PCI: Probing PCI hardware\n");
	pci_scan_bus(0, &generic_pci_ops, NULL);
	if (ppc_md.pcibios_fixup)
		ppc_md.pcibios_fixup();
	pcibios_allocate_bus_resources(&pci_root_buses);
	pcibios_allocate_resources(0);
	pcibios_allocate_resources(1);
	pcibios_assign_resources();
}

void __init
pcibios_fixup_pbus_ranges(struct pci_bus * bus, struct pbus_set_ranges_data * ranges)
{
	ranges->io_start -= bus->resource[0]->start;
	ranges->io_end -= bus->resource[0]->start;
	ranges->mem_start -= bus->resource[1]->start;
	ranges->mem_end -= bus->resource[1]->start;
}


void __init pcibios_fixup_bus(struct pci_bus *bus)
{
	if ( ppc_md.pcibios_fixup_bus )
		ppc_md.pcibios_fixup_bus(bus);
}

char __init *pcibios_setup(char *str)
{
	return str;
}

/* the next one is stolen from the alpha port... */
void __init
pcibios_update_irq(struct pci_dev *dev, int irq)
{
	pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq);
	/* XXX FIXME - update OF device tree node interrupt property */
}

int pcibios_enable_device(struct pci_dev *dev)
{
	u16 cmd, old_cmd;
	int idx;
	struct resource *r;

	pci_read_config_word(dev, PCI_COMMAND, &cmd);
	old_cmd = cmd;
	for (idx=0; idx<6; idx++) {
		r = &dev->resource[idx];
		if (!r->start && r->end) {
			printk(KERN_ERR "PCI: Device %s not available because of resource collisions\n", dev->slot_name);
			return -EINVAL;
		}
		if (r->flags & IORESOURCE_IO)
			cmd |= PCI_COMMAND_IO;
		if (r->flags & IORESOURCE_MEM)
			cmd |= PCI_COMMAND_MEMORY;
	}
	if (cmd != old_cmd) {
		printk("PCI: Enabling device %s (%04x -> %04x)\n",
		       dev->slot_name, old_cmd, cmd);
		pci_write_config_word(dev, PCI_COMMAND, cmd);
	}
	return 0;
}

void *
pci_dev_io_base(unsigned char bus, unsigned char devfn, int physical)
{
	if (!ppc_md.pci_dev_io_base) {
		/* Please, someone fix this for non-pmac machines, we
		 * need either the virtual or physical PCI IO base
		 */
		return 0;
	}
	return ppc_md.pci_dev_io_base(bus, devfn, physical);
}

void *
pci_dev_mem_base(unsigned char bus, unsigned char devfn)
{
	/* Default memory base is 0 (1:1 mapping) */
	if (!ppc_md.pci_dev_mem_base) {
		/* Please, someone fix this for non-pmac machines.*/
		return 0;
	}
	return ppc_md.pci_dev_mem_base(bus, devfn);
}

/* Returns the root-bridge number (Uni-N number) of a device */
int
pci_dev_root_bridge(unsigned char bus, unsigned char devfn)
{
	/* Defaults to 0 */
	if (!ppc_md.pci_dev_root_bridge)
		return 0;
	return ppc_md.pci_dev_root_bridge(bus, devfn);
}

/* Provide information on locations of various I/O regions in physical
 * memory.  Do this on a per-card basis so that we choose the right
 * root bridge.
 * Note that the returned IO or memory base is a physical address
 */

asmlinkage long
sys_pciconfig_iobase(long which, unsigned long bus, unsigned long devfn)
{
	long result = -EOPNOTSUPP;
	
	switch (which) {
	case IOBASE_BRIDGE_NUMBER:
		return (long)pci_dev_root_bridge(bus, devfn);
	case IOBASE_MEMORY:
		return (long)pci_dev_mem_base(bus, devfn);
	case IOBASE_IO:
		result = (long)pci_dev_io_base(bus, devfn, 1);
		if (result == 0)
			result = -EOPNOTSUPP;
		break;
	}

	return result;
}