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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/kernel/io_delay.c
10817 views
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/*

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 * I/O delay strategies for inb_p/outb_p

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 *

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 * Allow for a DMI based override of port 0x80, needed for certain HP laptops

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 * and possibly other systems. Also allow for the gradual elimination of

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 * outb_p/inb_p API uses.

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 */

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#include <linux/kernel.h>

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#include <linux/module.h>

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#include <linux/delay.h>

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#include <linux/init.h>

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#include <linux/dmi.h>

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#include <linux/io.h>

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int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;

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static int __initdata io_delay_override;

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/*

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 * Paravirt wants native_io_delay to be a constant.

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 */

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void native_io_delay(void)

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{

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	switch (io_delay_type) {

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	default:

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	case CONFIG_IO_DELAY_TYPE_0X80:

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		asm volatile ("outb %al, $0x80");

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		break;

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	case CONFIG_IO_DELAY_TYPE_0XED:

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		asm volatile ("outb %al, $0xed");

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		break;

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	case CONFIG_IO_DELAY_TYPE_UDELAY:

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		/*

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		 * 2 usecs is an upper-bound for the outb delay but

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		 * note that udelay doesn't have the bus-level

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		 * side-effects that outb does, nor does udelay() have

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		 * precise timings during very early bootup (the delays

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		 * are shorter until calibrated):

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		 */

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		udelay(2);

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	case CONFIG_IO_DELAY_TYPE_NONE:

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		break;

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	}

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}

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EXPORT_SYMBOL(native_io_delay);

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static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)

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{

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	if (io_delay_type == CONFIG_IO_DELAY_TYPE_0X80) {

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		pr_notice("%s: using 0xed I/O delay port\n", id->ident);

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		io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;

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	}

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	return 0;

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}

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/*

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 * Quirk table for systems that misbehave (lock up, etc.) if port

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 * 0x80 is used:

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 */

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static struct dmi_system_id __initdata io_delay_0xed_port_dmi_table[] = {

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	{

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		.callback	= dmi_io_delay_0xed_port,

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		.ident		= "Compaq Presario V6000",

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		.matches	= {

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			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),

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			DMI_MATCH(DMI_BOARD_NAME,	"30B7")

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		}

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	},

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	{

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		.callback	= dmi_io_delay_0xed_port,

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		.ident		= "HP Pavilion dv9000z",

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		.matches	= {

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			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),

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			DMI_MATCH(DMI_BOARD_NAME,	"30B9")

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		}

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	},

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	{

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		.callback	= dmi_io_delay_0xed_port,

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		.ident		= "HP Pavilion dv6000",

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		.matches	= {

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			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),

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			DMI_MATCH(DMI_BOARD_NAME,	"30B8")

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		}

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	},

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	{

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		.callback	= dmi_io_delay_0xed_port,

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		.ident		= "HP Pavilion tx1000",

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		.matches	= {

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			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),

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			DMI_MATCH(DMI_BOARD_NAME,	"30BF")

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		}

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	},

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	{

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		.callback	= dmi_io_delay_0xed_port,

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		.ident		= "Presario F700",

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		.matches	= {

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			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),

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			DMI_MATCH(DMI_BOARD_NAME,	"30D3")

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		}

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	},

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	{ }

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};

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void __init io_delay_init(void)

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{

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	if (!io_delay_override)

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		dmi_check_system(io_delay_0xed_port_dmi_table);

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}

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static int __init io_delay_param(char *s)

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{

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	if (!s)

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		return -EINVAL;

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	if (!strcmp(s, "0x80"))

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		io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;

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	else if (!strcmp(s, "0xed"))

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		io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;

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	else if (!strcmp(s, "udelay"))

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		io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;

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	else if (!strcmp(s, "none"))

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		io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;

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	else

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		return -EINVAL;

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	io_delay_override = 1;

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	return 0;

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}

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early_param("io_delay", io_delay_param);

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