1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * 8237A DMA controller suspend functions.
 4 *
 5 * Written by Pierre Ossman, 2005.
 
 
 
 
 
 6 */
 7
 8#include <linux/dmi.h>
 9#include <linux/init.h>
10#include <linux/syscore_ops.h>
11
12#include <asm/dma.h>
13#include <asm/x86_init.h>
14
15/*
16 * This module just handles suspend/resume issues with the
17 * 8237A DMA controller (used for ISA and LPC).
18 * Allocation is handled in kernel/dma.c and normal usage is
19 * in asm/dma.h.
20 */
21
22static void i8237A_resume(void)
23{
24	unsigned long flags;
25	int i;
26
27	flags = claim_dma_lock();
28
29	dma_outb(0, DMA1_RESET_REG);
30	dma_outb(0, DMA2_RESET_REG);
31
32	for (i = 0; i < 8; i++) {
33		set_dma_addr(i, 0x000000);
34		/* DMA count is a bit weird so this is not 0 */
35		set_dma_count(i, 1);
36	}
37
38	/* Enable cascade DMA or channel 0-3 won't work */
39	enable_dma(4);
40
41	release_dma_lock(flags);
42}
43
44static struct syscore_ops i8237_syscore_ops = {
45	.resume		= i8237A_resume,
46};
47
48static int __init i8237A_init_ops(void)
49{
50	/*
51	 * From SKL PCH onwards, the legacy DMA device is removed in which the
52	 * I/O ports (81h-83h, 87h, 89h-8Bh, 8Fh) related to it are removed
53	 * as well. All removed ports must return 0xff for a inb() request.
54	 *
55	 * Note: DMA_PAGE_2 (port 0x81) should not be checked for detecting
56	 * the presence of DMA device since it may be used by BIOS to decode
57	 * LPC traffic for POST codes. Original LPC only decodes one byte of
58	 * port 0x80 but some BIOS may choose to enhance PCH LPC port 0x8x
59	 * decoding.
60	 */
61	if (dma_inb(DMA_PAGE_0) == 0xFF)
62		return -ENODEV;
63
64	/*
65	 * It is not required to load this driver as newer SoC may not
66	 * support 8237 DMA or bus mastering from LPC. Platform firmware
67	 * must announce the support for such legacy devices via
68	 * ACPI_FADT_LEGACY_DEVICES field in FADT table.
69	 */
70	if (x86_pnpbios_disabled() && dmi_get_bios_year() >= 2017)
71		return -ENODEV;
72
73	register_syscore_ops(&i8237_syscore_ops);
74	return 0;
75}
76device_initcall(i8237A_init_ops);

 
 1/*
 2 * 8237A DMA controller suspend functions.
 3 *
 4 * Written by Pierre Ossman, 2005.
 5 *
 6 * This program is free software; you can redistribute it and/or modify
 7 * it under the terms of the GNU General Public License as published by
 8 * the Free Software Foundation; either version 2 of the License, or (at
 9 * your option) any later version.
10 */
11
 
12#include <linux/init.h>
13#include <linux/syscore_ops.h>
14
15#include <asm/dma.h>
 
16
17/*
18 * This module just handles suspend/resume issues with the
19 * 8237A DMA controller (used for ISA and LPC).
20 * Allocation is handled in kernel/dma.c and normal usage is
21 * in asm/dma.h.
22 */
23
24static void i8237A_resume(void)
25{
26	unsigned long flags;
27	int i;
28
29	flags = claim_dma_lock();
30
31	dma_outb(0, DMA1_RESET_REG);
32	dma_outb(0, DMA2_RESET_REG);
33
34	for (i = 0; i < 8; i++) {
35		set_dma_addr(i, 0x000000);
36		/* DMA count is a bit weird so this is not 0 */
37		set_dma_count(i, 1);
38	}
39
40	/* Enable cascade DMA or channel 0-3 won't work */
41	enable_dma(4);
42
43	release_dma_lock(flags);
44}
45
46static struct syscore_ops i8237_syscore_ops = {
47	.resume		= i8237A_resume,
48};
49
50static int __init i8237A_init_ops(void)
51{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
52	register_syscore_ops(&i8237_syscore_ops);
53	return 0;
54}
55device_initcall(i8237A_init_ops);