1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2007-2017 Cavium, Inc.
4 */
5#include <asm/asm.h>
6#include <asm/regdef.h>
7
8#define CVMSEG_BASE -32768
9#define CVMSEG_SIZE 6912
10#define SAVE_REG(r) sd $r, CVMSEG_BASE + CVMSEG_SIZE - ((32 - r) * 8)($0)
11
12 NESTED(octeon_wdt_nmi_stage2, 0, sp)
13 .set push
14 .set noreorder
15 .set noat
16 /* Clear Dcache so cvmseg works right. */
17 cache 1,0($0)
18 /* Use K0 to do a read/modify/write of CVMMEMCTL */
19 dmfc0 k0, $11, 7
20 /* Clear out the size of CVMSEG */
21 dins k0, $0, 0, 6
22 /* Set CVMSEG to its largest value */
23 ori k0, k0, 0x1c0 | 54
24 /* Store the CVMMEMCTL value */
25 dmtc0 k0, $11, 7
26 /*
27 * Restore K0 from the debug scratch register, it was saved in
28 * the boot-vector code.
29 */
30 dmfc0 k0, $31
31
32 /*
33 * Save all registers to the top CVMSEG. This shouldn't
34 * corrupt any state used by the kernel. Also all registers
35 * should have the value right before the NMI.
36 */
37 SAVE_REG(0)
38 SAVE_REG(1)
39 SAVE_REG(2)
40 SAVE_REG(3)
41 SAVE_REG(4)
42 SAVE_REG(5)
43 SAVE_REG(6)
44 SAVE_REG(7)
45 SAVE_REG(8)
46 SAVE_REG(9)
47 SAVE_REG(10)
48 SAVE_REG(11)
49 SAVE_REG(12)
50 SAVE_REG(13)
51 SAVE_REG(14)
52 SAVE_REG(15)
53 SAVE_REG(16)
54 SAVE_REG(17)
55 SAVE_REG(18)
56 SAVE_REG(19)
57 SAVE_REG(20)
58 SAVE_REG(21)
59 SAVE_REG(22)
60 SAVE_REG(23)
61 SAVE_REG(24)
62 SAVE_REG(25)
63 SAVE_REG(26)
64 SAVE_REG(27)
65 SAVE_REG(28)
66 SAVE_REG(29)
67 SAVE_REG(30)
68 SAVE_REG(31)
69 /* Write zero to all CVMSEG locations per Core-15169 */
70 dli a0, CVMSEG_SIZE - (33 * 8)
711: sd zero, CVMSEG_BASE(a0)
72 daddiu a0, a0, -8
73 bgez a0, 1b
74 nop
75 /* Set the stack to begin right below the registers */
76 dli sp, CVMSEG_BASE + CVMSEG_SIZE - (32 * 8)
77 /* Load the address of the third stage handler */
78 dla $25, octeon_wdt_nmi_stage3
79 /* Call the third stage handler */
80 jal $25
81 /* a0 is the address of the saved registers */
82 move a0, sp
83 /* Loop forvever if we get here. */
842: b 2b
85 nop
86 .set pop
87 END(octeon_wdt_nmi_stage2)
88

source code of linux/drivers/watchdog/octeon-wdt-nmi.S