diff options
Diffstat (limited to 'arch/x86/kernel/io_delay.c')
| -rw-r--r-- | arch/x86/kernel/io_delay.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/arch/x86/kernel/io_delay.c b/arch/x86/kernel/io_delay.c new file mode 100644 index 000000000..fdb6506ce --- /dev/null +++ b/arch/x86/kernel/io_delay.c @@ -0,0 +1,148 @@ +// 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); |