// SPDX-License-Identifier: GPL-2.0/* * I/O delay strategies for inb_p/outb_p * * Allow for a DMI based override of port 0x80, needed for certain HP laptops * and possibly other systems. Also allow for the gradual elimination of * outb_p/inb_p API uses. */#include <linux/kernel.h>#include <linux/export.h>#include <linux/delay.h>#include <linux/init.h>#include <linux/dmi.h>#include <linux/io.h> #define IO_DELAY_TYPE_0X80	0#define IO_DELAY_TYPE_0XED	1#define IO_DELAY_TYPE_UDELAY	2#define IO_DELAY_TYPE_NONE	3 #if defined(CONFIG_IO_DELAY_0X80)#define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_0X80#elif defined(CONFIG_IO_DELAY_0XED)#define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_0XED#elif defined(CONFIG_IO_DELAY_UDELAY)#define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_UDELAY#elif defined(CONFIG_IO_DELAY_NONE)#define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_NONE#endif int io_delay_type __read_mostly = DEFAULT_IO_DELAY_TYPE; static int __initdata io_delay_override; /* * Paravirt wants native_io_delay to be a constant. */void native_io_delay(void){	switch (io_delay_type) {	default:	case IO_DELAY_TYPE_0X80:		asm volatile ("outb %al, $0x80");		break;	case IO_DELAY_TYPE_0XED:		asm volatile ("outb %al, $0xed");		break;	case IO_DELAY_TYPE_UDELAY:		/*		 * 2 usecs is an upper-bound for the outb delay but		 * note that udelay doesn't have the bus-level		 * side-effects that outb does, nor does udelay() have		 * precise timings during very early bootup (the delays		 * are shorter until calibrated):		 */		udelay(2);		break;	case IO_DELAY_TYPE_NONE:		break;	}}EXPORT_SYMBOL(native_io_delay); static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id){	if (io_delay_type == IO_DELAY_TYPE_0X80) {		pr_notice("%s: using 0xed I/O delay port\n", id->ident);		io_delay_type = IO_DELAY_TYPE_0XED;	} 	return 0;} /* * Quirk table for systems that misbehave (lock up, etc.) if port * 0x80 is used: */static const struct dmi_system_id io_delay_0xed_port_dmi_table[] __initconst = {	{		.callback	= dmi_io_delay_0xed_port,		.ident		= "Compaq Presario V6000",		.matches	= {			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),			DMI_MATCH(DMI_BOARD_NAME,	"30B7")		}	},	{		.callback	= dmi_io_delay_0xed_port,		.ident		= "HP Pavilion dv9000z",		.matches	= {			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),			DMI_MATCH(DMI_BOARD_NAME,	"30B9")		}	},	{		.callback	= dmi_io_delay_0xed_port,		.ident		= "HP Pavilion dv6000",		.matches	= {			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),			DMI_MATCH(DMI_BOARD_NAME,	"30B8")		}	},	{		.callback	= dmi_io_delay_0xed_port,		.ident		= "HP Pavilion tx1000",		.matches	= {			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),			DMI_MATCH(DMI_BOARD_NAME,	"30BF")		}	},	{		.callback	= dmi_io_delay_0xed_port,		.ident		= "Presario F700",		.matches	= {			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),			DMI_MATCH(DMI_BOARD_NAME,	"30D3")		}	},	{ }}; void __init io_delay_init(void){	if (!io_delay_override)		dmi_check_system(io_delay_0xed_port_dmi_table);} static int __init io_delay_param(char *s){	if (!s)		return -EINVAL; 	if (!strcmp(s, "0x80"))		io_delay_type = IO_DELAY_TYPE_0X80;	else if (!strcmp(s, "0xed"))		io_delay_type = IO_DELAY_TYPE_0XED;	else if (!strcmp(s, "udelay"))		io_delay_type = IO_DELAY_TYPE_UDELAY;	else if (!strcmp(s, "none"))		io_delay_type = IO_DELAY_TYPE_NONE;	else		return -EINVAL; 	io_delay_override = 1;	return 0;} early_param("io_delay", io_delay_param);