1 // SPDX-License-Identifier: GPL-2.0-or-later 1
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 iss
17 * 8237A DMA controller (used for ISA and LPC)
18 * Allocation is handled in kernel/dma.c and n
19 * in asm/dma.h.
20 */
21
22 static 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
35 set_dma_count(i, 1);
36 }
37
38 /* Enable cascade DMA or channel 0-3 w
39 enable_dma(4);
40
41 release_dma_lock(flags);
42 }
43
44 static struct syscore_ops i8237_syscore_ops =
45 .resume = i8237A_resume,
46 };
47
48 static int __init i8237A_init_ops(void)
49 {
50 /*
51 * From SKL PCH onwards, the legacy DM
52 * I/O ports (81h-83h, 87h, 89h-8Bh, 8
53 * as well. All removed ports must ret
54 *
55 * Note: DMA_PAGE_2 (port 0x81) should
56 * the presence of DMA device since it
57 * LPC traffic for POST codes. Origina
58 * port 0x80 but some BIOS may choose
59 * decoding.
60 */
61 if (dma_inb(DMA_PAGE_0) == 0xFF)
62 return -ENODEV;
63
64 /*
65 * It is not required to load this dri
66 * support 8237 DMA or bus mastering f
67 * must announce the support for such
68 * ACPI_FADT_LEGACY_DEVICES field in F
69 */
70 if (x86_pnpbios_disabled() && dmi_get_
71 return -ENODEV;
72
73 register_syscore_ops(&i8237_syscore_op
74 return 0;
75 }
76 device_initcall(i8237A_init_ops);
77
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