diff options
Diffstat (limited to 'arch/x86/kernel/i8237.c')
| -rw-r--r-- | arch/x86/kernel/i8237.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/kernel/i8237.c b/arch/x86/kernel/i8237.c index 8eeaa81de066..0a3e70fd00d6 100644 --- a/arch/x86/kernel/i8237.c +++ b/arch/x86/kernel/i8237.c @@ -9,10 +9,12 @@ * your option) any later version. */ +#include <linux/dmi.h> #include <linux/init.h> #include <linux/syscore_ops.h> #include <asm/dma.h> +#include <asm/x86_init.h> /* * This module just handles suspend/resume issues with the @@ -49,6 +51,29 @@ static struct syscore_ops i8237_syscore_ops = { static int __init i8237A_init_ops(void) { + /* + * From SKL PCH onwards, the legacy DMA device is removed in which the + * I/O ports (81h-83h, 87h, 89h-8Bh, 8Fh) related to it are removed + * as well. All removed ports must return 0xff for a inb() request. + * + * Note: DMA_PAGE_2 (port 0x81) should not be checked for detecting + * the presence of DMA device since it may be used by BIOS to decode + * LPC traffic for POST codes. Original LPC only decodes one byte of + * port 0x80 but some BIOS may choose to enhance PCH LPC port 0x8x + * decoding. + */ + if (dma_inb(DMA_PAGE_0) == 0xFF) + return -ENODEV; + + /* + * It is not required to load this driver as newer SoC may not + * support 8237 DMA or bus mastering from LPC. Platform firmware + * must announce the support for such legacy devices via + * ACPI_FADT_LEGACY_DEVICES field in FADT table. + */ + if (x86_pnpbios_disabled() && dmi_get_bios_year() >= 2017) + return -ENODEV; + register_syscore_ops(&i8237_syscore_ops); return 0; } |