pci-irq.c

讲述linux的初始化过程

/*
 *	Low-Level PCI Support for PC -- Routing of Interrupts
 *
 *	(c) 1999--2000 Martin Mares <[e-mail]>
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/malloc.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <asm/io.h>
#include <asm/smp.h>
#include <asm/io_apic.h>

#include "pci-i386.h"

#define PIRQ_SIGNATURE	(('$' << 0) + ('P' << 8) + ('I' << 16) + ('R' << 24))
#define PIRQ_VERSION 0x0100

static struct irq_routing_table *pirq_table;

/*
 * Never use: 0, 1, 2 (timer, keyboard, and cascade)
 * Avoid using: 13, 14 and 15 (FP error and IDE).
 * Penalize: 3, 4, 6, 7, 12 (known ISA uses: serial, floppy, parallel and mouse)
 */
unsigned int pcibios_irq_mask = 0xfff8;

static int pirq_penalty[16] = {
	1000000, 1000000, 1000000, 1000, 1000, 0, 1000, 1000,
	0, 0, 0, 0, 1000, 100000, 100000, 100000
};

struct irq_router {
	char *name;
	u16 vendor, device;
	int (*get)(struct pci_dev *router, struct pci_dev *dev, int pirq);
	int (*set)(struct pci_dev *router, struct pci_dev *dev, int pirq, int new);
};

/*
 *  Search 0xf0000 -- 0xfffff for the PCI IRQ Routing Table.
 */

static struct irq_routing_table * __init pirq_find_routing_table(void)
{
	u8 *addr;
	struct irq_routing_table *rt;
	int i;
	u8 sum;

	for(addr = (u8 *) __va(0xf0000); addr < (u8 *) __va(0x100000); addr += 16) {
		rt = (struct irq_routing_table *) addr;
		if (rt->signature != PIRQ_SIGNATURE ||
		    rt->version != PIRQ_VERSION ||
		    rt->size % 16 ||
		    rt->size < sizeof(struct irq_routing_table))
			continue;
		sum = 0;
		for(i=0; i<rt->size; i++)
			sum += addr[i];
		if (!sum) {
			DBG("PCI: Interrupt Routing Table found at 0x%p\n", rt);
			return rt;
		}
	}
	return NULL;
}

/*
 *  If we have a IRQ routing table, use it to search for peer host
 *  bridges.  It's a gross hack, but since there are no other known
 *  ways how to get a list of buses, we have to go this way.
 */

static void __init pirq_peer_trick(void)
{
	struct irq_routing_table *rt = pirq_table;
	u8 busmap[256];
	int i;
	struct irq_info *e;

	memset(busmap, 0, sizeof(busmap));
	for(i=0; i < (rt->size - sizeof(struct irq_routing_table)) / sizeof(struct irq_info); i++) {
		e = &rt->slots[i];
#ifdef DEBUG
		{
			int j;
			DBG("%02x:%02x slot=%02x", e->bus, e->devfn/8, e->slot);
			for(j=0; j<4; j++)
				DBG(" %d:%02x/%04x", j, e->irq[j].link, e->irq[j].bitmap);
			DBG("\n");
		}
#endif
		busmap[e->bus] = 1;
	}
	for(i=1; i<256; i++)
		/*
		 *  It might be a secondary bus, but in this case its parent is already
		 *  known (ascending bus order) and therefore pci_scan_bus returns immediately.
		 */
		if (busmap[i] && pci_scan_bus(i, pci_root_bus->ops, NULL))
			printk("PCI: Discovered primary peer bus %02x [IRQ]\n", i);
	pcibios_last_bus = -1;
}

/*
 *  Code for querying and setting of IRQ routes on various interrupt routers.
 */

static void eisa_set_level_irq(unsigned int irq)
{
	unsigned char mask = 1 << (irq & 7);
	unsigned int port = 0x4d0 + (irq >> 3);
	unsigned char val = inb(port);

	if (!(val & mask)) {
		DBG(" -> edge");
		outb(val | mask, port);
	}
}

/*
 * Common IRQ routing practice: nybbles in config space,
 * offset by some magic constant.
 */
static unsigned int read_config_nybble(struct pci_dev *router, unsigned offset, unsigned nr)
{
	u8 x;
	unsigned reg = offset + (nr >> 1);

	pci_read_config_byte(router, reg, &x);
	return (nr & 1) ? (x >> 4) : (x & 0xf);
}

static void write_config_nybble(struct pci_dev *router, unsigned offset, unsigned nr, unsigned int val)
{
	u8 x;
	unsigned reg = offset + (nr >> 1);

	pci_read_config_byte(router, reg, &x);
	x = (nr & 1) ? ((x & 0x0f) | (val << 4)) : ((x & 0xf0) | val);
	pci_write_config_byte(router, reg, x);
}

/*
 * ALI pirq entries are damn ugly, and completely undocumented.
 * This has been figured out from pirq tables, and it's not a pretty
 * picture.
 */
static int pirq_ali_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	static unsigned char irqmap[16] = { 0, 9, 3, 10, 4, 5, 7, 6, 1, 11, 0, 12, 0, 14, 0, 15 };

	return irqmap[read_config_nybble(router, 0x48, pirq-1)];
}

static int pirq_ali_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	static unsigned char irqmap[16] = { 0, 8, 0, 2, 4, 5, 7, 6, 0, 1, 3, 9, 11, 0, 13, 15 };
	unsigned int val = irqmap[irq];
		
	if (val) {
		write_config_nybble(router, 0x48, pirq-1, val);
		return 1;
	}
	return 0;
}

/*
 * The Intel PIIX4 pirq rules are fairly simple: "pirq" is
 * just a pointer to the config space.
 */
static int pirq_piix_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	u8 x;

	pci_read_config_byte(router, pirq, &x);
	return (x < 16) ? x : 0;
}

static int pirq_piix_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	pci_write_config_byte(router, pirq, irq);
	return 1;
}

/*
 * The VIA pirq rules are nibble-based, like ALI,
 * but without the ugly irq number munging.
 */
static int pirq_via_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	return read_config_nybble(router, 0x55, pirq);
}

static int pirq_via_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	write_config_nybble(router, 0x55, pirq, irq);
	return 1;
}

/*
 * OPTI: high four bits are nibble pointer..
 * I wonder what the low bits do?
 */
static int pirq_opti_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	return read_config_nybble(router, 0xb8, pirq >> 4);
}

static int pirq_opti_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	write_config_nybble(router, 0xb8, pirq >> 4, irq);
	return 1;
}

/*
 * Cyrix: nibble offset 0x5C
 */
static int pirq_cyrix_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	return read_config_nybble(router, 0x5C, pirq-1);
}

static int pirq_cyrix_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	write_config_nybble(router, 0x5C, pirq-1, irq);
	return 1;
}

static int pirq_sis_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	u8 x;
	int reg = 0x41 + (pirq - 'A') ;

	pci_read_config_byte(router, reg, &x);
	return (x & 0x80) ? 0 : (x & 0x0f);
}

static int pirq_sis_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	u8 x;
	int reg = 0x41 + (pirq - 'A') ;

	pci_read_config_byte(router, reg, &x);
	x = (pirq & 0x20) ? 0 : (irq & 0x0f);
	pci_write_config_byte(router, reg, x);

	return 1;
}

/*
 * VLSI: nibble offset 0x74 - educated guess due to routing table and
 *       config space of VLSI 82C534 PCI-bridge/router (1004:0102)
 *       Tested on HP OmniBook 800 covering PIRQ 1, 2, 4, 8 for onboard
 *       devices, PIRQ 3 for non-pci(!) soundchip and (untested) PIRQ 6
 *       for the busbridge to the docking station.
 */

static int pirq_vlsi_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	if (pirq > 8) {
		printk("VLSI router pirq escape (%d)\n", pirq);
		return 0;
	}
	return read_config_nybble(router, 0x74, pirq-1);
}

static int pirq_vlsi_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	if (pirq > 8) {
		printk("VLSI router pirq escape (%d)\n", pirq);
		return 0;
	}
	write_config_nybble(router, 0x74, pirq-1, irq);
	return 1;
}

/*
 * ServerWorks: PCI interrupts mapped to system IRQ lines through Index
 * and Redirect I/O registers (0x0c00 and 0x0c01).  The Index register
 * format is (PCIIRQ## | 0x10), e.g.: PCIIRQ10=0x1a.  The Redirect
 * register is a straight binary coding of desired PIC IRQ (low nibble).
 *
 * The 'link' value in the PIRQ table is already in the correct format
 * for the Index register.  There are some special index values:
 * 0x00 for ACPI (SCI), 0x01 for USB, 0x02 for IDE0, 0x04 for IDE1,
 * and 0x03 for SMBus.
 */
static int pirq_serverworks_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
{
	outb_p(pirq, 0xc00);
	return inb(0xc01) & 0xf;
}

static int pirq_serverworks_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	outb_p(pirq, 0xc00);
	outb_p(irq, 0xc01);
	return 1;
}

#ifdef CONFIG_PCI_BIOS

static int pirq_bios_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
{
	struct pci_dev *bridge;
	int pin = pci_get_interrupt_pin(dev, &bridge);
	return pcibios_set_irq_routing(bridge, pin, irq);