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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
69c75fb4 | 2 | /* |
69c75fb4 MR |
3 | * Bus error event handling code for DECstation/DECsystem 3100 |
4 | * and 2100 (KN01) systems equipped with parity error detection | |
5 | * logic. | |
6 | * | |
7 | * Copyright (c) 2005 Maciej W. Rozycki | |
69c75fb4 MR |
8 | */ |
9 | ||
10 | #include <linux/init.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/spinlock.h> | |
14 | #include <linux/types.h> | |
15 | ||
16 | #include <asm/inst.h> | |
49afb1f6 | 17 | #include <asm/irq_regs.h> |
69c75fb4 MR |
18 | #include <asm/mipsregs.h> |
19 | #include <asm/page.h> | |
49afb1f6 | 20 | #include <asm/ptrace.h> |
69c75fb4 | 21 | #include <asm/traps.h> |
7c0f6ba6 | 22 | #include <linux/uaccess.h> |
69c75fb4 MR |
23 | |
24 | #include <asm/dec/kn01.h> | |
25 | ||
26 | ||
27 | /* CP0 hazard avoidance. */ | |
28 | #define BARRIER \ | |
29 | __asm__ __volatile__( \ | |
30 | ".set push\n\t" \ | |
31 | ".set noreorder\n\t" \ | |
32 | "nop\n\t" \ | |
33 | ".set pop\n\t") | |
34 | ||
35 | /* | |
36 | * Bits 7:0 of the Control Register are write-only -- the | |
37 | * corresponding bits of the Status Register have a different | |
38 | * meaning. Hence we use a cache. It speeds up things a bit | |
39 | * as well. | |
40 | * | |
41 | * There is no default value -- it has to be initialized. | |
42 | */ | |
43 | u16 cached_kn01_csr; | |
32baba2f | 44 | static DEFINE_RAW_SPINLOCK(kn01_lock); |
69c75fb4 MR |
45 | |
46 | ||
47 | static inline void dec_kn01_be_ack(void) | |
48 | { | |
a5fc9c0b | 49 | volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); |
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50 | unsigned long flags; |
51 | ||
32baba2f | 52 | raw_spin_lock_irqsave(&kn01_lock, flags); |
69c75fb4 MR |
53 | |
54 | *csr = cached_kn01_csr | KN01_CSR_MEMERR; /* Clear bus IRQ. */ | |
55 | iob(); | |
56 | ||
32baba2f | 57 | raw_spin_unlock_irqrestore(&kn01_lock, flags); |
69c75fb4 MR |
58 | } |
59 | ||
60 | static int dec_kn01_be_backend(struct pt_regs *regs, int is_fixup, int invoker) | |
61 | { | |
a5fc9c0b MR |
62 | volatile u32 *kn01_erraddr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + |
63 | KN01_ERRADDR); | |
69c75fb4 MR |
64 | |
65 | static const char excstr[] = "exception"; | |
66 | static const char intstr[] = "interrupt"; | |
67 | static const char cpustr[] = "CPU"; | |
68 | static const char mreadstr[] = "memory read"; | |
69 | static const char readstr[] = "read"; | |
70 | static const char writestr[] = "write"; | |
71 | static const char timestr[] = "timeout"; | |
72 | static const char paritystr[] = "parity error"; | |
73 | ||
74 | int data = regs->cp0_cause & 4; | |
75 | unsigned int __user *pc = (unsigned int __user *)regs->cp0_epc + | |
76 | ((regs->cp0_cause & CAUSEF_BD) != 0); | |
77 | union mips_instruction insn; | |
78 | unsigned long entrylo, offset; | |
79 | long asid, entryhi, vaddr; | |
80 | ||
81 | const char *kind, *agent, *cycle, *event; | |
82 | unsigned long address; | |
83 | ||
84 | u32 erraddr = *kn01_erraddr; | |
85 | int action = MIPS_BE_FATAL; | |
86 | ||
87 | /* Ack ASAP, so that any subsequent errors get caught. */ | |
88 | dec_kn01_be_ack(); | |
89 | ||
90 | kind = invoker ? intstr : excstr; | |
91 | ||
92 | agent = cpustr; | |
93 | ||
94 | if (invoker) | |
95 | address = erraddr; | |
96 | else { | |
97 | /* Bloody hardware doesn't record the address for reads... */ | |
98 | if (data) { | |
99 | /* This never faults. */ | |
100 | __get_user(insn.word, pc); | |
101 | vaddr = regs->regs[insn.i_format.rs] + | |
102 | insn.i_format.simmediate; | |
103 | } else | |
104 | vaddr = (long)pc; | |
105 | if (KSEGX(vaddr) == CKSEG0 || KSEGX(vaddr) == CKSEG1) | |
106 | address = CPHYSADDR(vaddr); | |
107 | else { | |
108 | /* Peek at what physical address the CPU used. */ | |
109 | asid = read_c0_entryhi(); | |
110 | entryhi = asid & (PAGE_SIZE - 1); | |
111 | entryhi |= vaddr & ~(PAGE_SIZE - 1); | |
112 | write_c0_entryhi(entryhi); | |
113 | BARRIER; | |
114 | tlb_probe(); | |
115 | /* No need to check for presence. */ | |
116 | tlb_read(); | |
117 | entrylo = read_c0_entrylo0(); | |
118 | write_c0_entryhi(asid); | |
119 | offset = vaddr & (PAGE_SIZE - 1); | |
120 | address = (entrylo & ~(PAGE_SIZE - 1)) | offset; | |
121 | } | |
122 | } | |
123 | ||
124 | /* Treat low 256MB as memory, high -- as I/O. */ | |
125 | if (address < 0x10000000) { | |
126 | cycle = mreadstr; | |
127 | event = paritystr; | |
128 | } else { | |
129 | cycle = invoker ? writestr : readstr; | |
130 | event = timestr; | |
131 | } | |
132 | ||
133 | if (is_fixup) | |
134 | action = MIPS_BE_FIXUP; | |
135 | ||
136 | if (action != MIPS_BE_FIXUP) | |
137 | printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n", | |
138 | kind, agent, cycle, event, address); | |
139 | ||
140 | return action; | |
141 | } | |
142 | ||
143 | int dec_kn01_be_handler(struct pt_regs *regs, int is_fixup) | |
144 | { | |
145 | return dec_kn01_be_backend(regs, is_fixup, 0); | |
146 | } | |
147 | ||
6dab2f45 | 148 | irqreturn_t dec_kn01_be_interrupt(int irq, void *dev_id) |
69c75fb4 | 149 | { |
a5fc9c0b | 150 | volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); |
6dab2f45 | 151 | struct pt_regs *regs = get_irq_regs(); |
69c75fb4 MR |
152 | int action; |
153 | ||
154 | if (!(*csr & KN01_CSR_MEMERR)) | |
155 | return IRQ_NONE; /* Must have been video. */ | |
156 | ||
157 | action = dec_kn01_be_backend(regs, 0, 1); | |
158 | ||
159 | if (action == MIPS_BE_DISCARD) | |
160 | return IRQ_HANDLED; | |
161 | ||
162 | /* | |
163 | * FIXME: Find the affected processes and kill them, otherwise | |
164 | * we must die. | |
165 | * | |
166 | * The interrupt is asynchronously delivered thus EPC and RA | |
167 | * may be irrelevant, but are printed for a reference. | |
168 | */ | |
169 | printk(KERN_ALERT "Fatal bus interrupt, epc == %08lx, ra == %08lx\n", | |
170 | regs->cp0_epc, regs->regs[31]); | |
171 | die("Unrecoverable bus error", regs); | |
172 | } | |
173 | ||
174 | ||
175 | void __init dec_kn01_be_init(void) | |
176 | { | |
a5fc9c0b | 177 | volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); |
69c75fb4 MR |
178 | unsigned long flags; |
179 | ||
32baba2f | 180 | raw_spin_lock_irqsave(&kn01_lock, flags); |
69c75fb4 MR |
181 | |
182 | /* Preset write-only bits of the Control Register cache. */ | |
183 | cached_kn01_csr = *csr; | |
184 | cached_kn01_csr &= KN01_CSR_STATUS | KN01_CSR_PARDIS | KN01_CSR_TXDIS; | |
185 | cached_kn01_csr |= KN01_CSR_LEDS; | |
186 | ||
187 | /* Enable parity error detection. */ | |
188 | cached_kn01_csr &= ~KN01_CSR_PARDIS; | |
189 | *csr = cached_kn01_csr; | |
190 | iob(); | |
191 | ||
32baba2f | 192 | raw_spin_unlock_irqrestore(&kn01_lock, flags); |
69c75fb4 MR |
193 | |
194 | /* Clear any leftover errors from the firmware. */ | |
195 | dec_kn01_be_ack(); | |
196 | } |