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69c75fb4 | 1 | /* |
69c75fb4 MR |
2 | * Bus error event handling code for DECstation/DECsystem 3100 |
3 | * and 2100 (KN01) systems equipped with parity error detection | |
4 | * logic. | |
5 | * | |
6 | * Copyright (c) 2005 Maciej W. Rozycki | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the License, or (at your option) any later version. | |
12 | */ | |
13 | ||
14 | #include <linux/init.h> | |
15 | #include <linux/interrupt.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/spinlock.h> | |
18 | #include <linux/types.h> | |
19 | ||
20 | #include <asm/inst.h> | |
49afb1f6 | 21 | #include <asm/irq_regs.h> |
69c75fb4 MR |
22 | #include <asm/mipsregs.h> |
23 | #include <asm/page.h> | |
49afb1f6 | 24 | #include <asm/ptrace.h> |
69c75fb4 | 25 | #include <asm/traps.h> |
7c0f6ba6 | 26 | #include <linux/uaccess.h> |
69c75fb4 MR |
27 | |
28 | #include <asm/dec/kn01.h> | |
29 | ||
30 | ||
31 | /* CP0 hazard avoidance. */ | |
32 | #define BARRIER \ | |
33 | __asm__ __volatile__( \ | |
34 | ".set push\n\t" \ | |
35 | ".set noreorder\n\t" \ | |
36 | "nop\n\t" \ | |
37 | ".set pop\n\t") | |
38 | ||
39 | /* | |
40 | * Bits 7:0 of the Control Register are write-only -- the | |
41 | * corresponding bits of the Status Register have a different | |
42 | * meaning. Hence we use a cache. It speeds up things a bit | |
43 | * as well. | |
44 | * | |
45 | * There is no default value -- it has to be initialized. | |
46 | */ | |
47 | u16 cached_kn01_csr; | |
32baba2f | 48 | static DEFINE_RAW_SPINLOCK(kn01_lock); |
69c75fb4 MR |
49 | |
50 | ||
51 | static inline void dec_kn01_be_ack(void) | |
52 | { | |
a5fc9c0b | 53 | volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); |
69c75fb4 MR |
54 | unsigned long flags; |
55 | ||
32baba2f | 56 | raw_spin_lock_irqsave(&kn01_lock, flags); |
69c75fb4 MR |
57 | |
58 | *csr = cached_kn01_csr | KN01_CSR_MEMERR; /* Clear bus IRQ. */ | |
59 | iob(); | |
60 | ||
32baba2f | 61 | raw_spin_unlock_irqrestore(&kn01_lock, flags); |
69c75fb4 MR |
62 | } |
63 | ||
64 | static int dec_kn01_be_backend(struct pt_regs *regs, int is_fixup, int invoker) | |
65 | { | |
a5fc9c0b MR |
66 | volatile u32 *kn01_erraddr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + |
67 | KN01_ERRADDR); | |
69c75fb4 MR |
68 | |
69 | static const char excstr[] = "exception"; | |
70 | static const char intstr[] = "interrupt"; | |
71 | static const char cpustr[] = "CPU"; | |
72 | static const char mreadstr[] = "memory read"; | |
73 | static const char readstr[] = "read"; | |
74 | static const char writestr[] = "write"; | |
75 | static const char timestr[] = "timeout"; | |
76 | static const char paritystr[] = "parity error"; | |
77 | ||
78 | int data = regs->cp0_cause & 4; | |
79 | unsigned int __user *pc = (unsigned int __user *)regs->cp0_epc + | |
80 | ((regs->cp0_cause & CAUSEF_BD) != 0); | |
81 | union mips_instruction insn; | |
82 | unsigned long entrylo, offset; | |
83 | long asid, entryhi, vaddr; | |
84 | ||
85 | const char *kind, *agent, *cycle, *event; | |
86 | unsigned long address; | |
87 | ||
88 | u32 erraddr = *kn01_erraddr; | |
89 | int action = MIPS_BE_FATAL; | |
90 | ||
91 | /* Ack ASAP, so that any subsequent errors get caught. */ | |
92 | dec_kn01_be_ack(); | |
93 | ||
94 | kind = invoker ? intstr : excstr; | |
95 | ||
96 | agent = cpustr; | |
97 | ||
98 | if (invoker) | |
99 | address = erraddr; | |
100 | else { | |
101 | /* Bloody hardware doesn't record the address for reads... */ | |
102 | if (data) { | |
103 | /* This never faults. */ | |
104 | __get_user(insn.word, pc); | |
105 | vaddr = regs->regs[insn.i_format.rs] + | |
106 | insn.i_format.simmediate; | |
107 | } else | |
108 | vaddr = (long)pc; | |
109 | if (KSEGX(vaddr) == CKSEG0 || KSEGX(vaddr) == CKSEG1) | |
110 | address = CPHYSADDR(vaddr); | |
111 | else { | |
112 | /* Peek at what physical address the CPU used. */ | |
113 | asid = read_c0_entryhi(); | |
114 | entryhi = asid & (PAGE_SIZE - 1); | |
115 | entryhi |= vaddr & ~(PAGE_SIZE - 1); | |
116 | write_c0_entryhi(entryhi); | |
117 | BARRIER; | |
118 | tlb_probe(); | |
119 | /* No need to check for presence. */ | |
120 | tlb_read(); | |
121 | entrylo = read_c0_entrylo0(); | |
122 | write_c0_entryhi(asid); | |
123 | offset = vaddr & (PAGE_SIZE - 1); | |
124 | address = (entrylo & ~(PAGE_SIZE - 1)) | offset; | |
125 | } | |
126 | } | |
127 | ||
128 | /* Treat low 256MB as memory, high -- as I/O. */ | |
129 | if (address < 0x10000000) { | |
130 | cycle = mreadstr; | |
131 | event = paritystr; | |
132 | } else { | |
133 | cycle = invoker ? writestr : readstr; | |
134 | event = timestr; | |
135 | } | |
136 | ||
137 | if (is_fixup) | |
138 | action = MIPS_BE_FIXUP; | |
139 | ||
140 | if (action != MIPS_BE_FIXUP) | |
141 | printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n", | |
142 | kind, agent, cycle, event, address); | |
143 | ||
144 | return action; | |
145 | } | |
146 | ||
147 | int dec_kn01_be_handler(struct pt_regs *regs, int is_fixup) | |
148 | { | |
149 | return dec_kn01_be_backend(regs, is_fixup, 0); | |
150 | } | |
151 | ||
6dab2f45 | 152 | irqreturn_t dec_kn01_be_interrupt(int irq, void *dev_id) |
69c75fb4 | 153 | { |
a5fc9c0b | 154 | volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); |
6dab2f45 | 155 | struct pt_regs *regs = get_irq_regs(); |
69c75fb4 MR |
156 | int action; |
157 | ||
158 | if (!(*csr & KN01_CSR_MEMERR)) | |
159 | return IRQ_NONE; /* Must have been video. */ | |
160 | ||
161 | action = dec_kn01_be_backend(regs, 0, 1); | |
162 | ||
163 | if (action == MIPS_BE_DISCARD) | |
164 | return IRQ_HANDLED; | |
165 | ||
166 | /* | |
167 | * FIXME: Find the affected processes and kill them, otherwise | |
168 | * we must die. | |
169 | * | |
170 | * The interrupt is asynchronously delivered thus EPC and RA | |
171 | * may be irrelevant, but are printed for a reference. | |
172 | */ | |
173 | printk(KERN_ALERT "Fatal bus interrupt, epc == %08lx, ra == %08lx\n", | |
174 | regs->cp0_epc, regs->regs[31]); | |
175 | die("Unrecoverable bus error", regs); | |
176 | } | |
177 | ||
178 | ||
179 | void __init dec_kn01_be_init(void) | |
180 | { | |
a5fc9c0b | 181 | volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); |
69c75fb4 MR |
182 | unsigned long flags; |
183 | ||
32baba2f | 184 | raw_spin_lock_irqsave(&kn01_lock, flags); |
69c75fb4 MR |
185 | |
186 | /* Preset write-only bits of the Control Register cache. */ | |
187 | cached_kn01_csr = *csr; | |
188 | cached_kn01_csr &= KN01_CSR_STATUS | KN01_CSR_PARDIS | KN01_CSR_TXDIS; | |
189 | cached_kn01_csr |= KN01_CSR_LEDS; | |
190 | ||
191 | /* Enable parity error detection. */ | |
192 | cached_kn01_csr &= ~KN01_CSR_PARDIS; | |
193 | *csr = cached_kn01_csr; | |
194 | iob(); | |
195 | ||
32baba2f | 196 | raw_spin_unlock_irqrestore(&kn01_lock, flags); |
69c75fb4 MR |
197 | |
198 | /* Clear any leftover errors from the firmware. */ | |
199 | dec_kn01_be_ack(); | |
200 | } |