1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Bus error event handling code for 5000-series systems equipped
4 * with parity error detection logic, i.e. DECstation/DECsystem
5 * 5000/120, /125, /133 (KN02-BA), 5000/150 (KN04-BA) and Personal
6 * DECstation/DECsystem 5000/20, /25, /33 (KN02-CA), 5000/50
7 * (KN04-CA) systems.
8 *
9 * Copyright (c) 2005 Maciej W. Rozycki
10 */
11
12 #include <linux/init.h>
13 #include <linux/interrupt.h>
14 #include <linux/kernel.h>
15 #include <linux/types.h>
16
17 #include <asm/addrspace.h>
18 #include <asm/cpu-type.h>
19 #include <asm/irq_regs.h>
20 #include <asm/ptrace.h>
21 #include <asm/traps.h>
22
23 #include <asm/dec/kn02ca.h>
24 #include <asm/dec/kn02xa.h>
25 #include <asm/dec/kn05.h>
26
27 static inline void dec_kn02xa_be_ack(void)
28 {
29 volatile u32 *mer = (void *)CKSEG1ADDR(KN02XA_MER);
30 volatile u32 *mem_intr = (void *)CKSEG1ADDR(KN02XA_MEM_INTR);
31
32 *mer = KN02CA_MER_INTR; /* Clear errors; keep the ARC IRQ. */
33 *mem_intr = 0; /* Any write clears the bus IRQ. */
34 iob();
35 }
36
37 static int dec_kn02xa_be_backend(struct pt_regs *regs, int is_fixup,
38 int invoker)
39 {
40 volatile u32 *kn02xa_mer = (void *)CKSEG1ADDR(KN02XA_MER);
41 volatile u32 *kn02xa_ear = (void *)CKSEG1ADDR(KN02XA_EAR);
42
43 static const char excstr[] = "exception";
44 static const char intstr[] = "interrupt";
45 static const char cpustr[] = "CPU";
46 static const char mreadstr[] = "memory read";
47 static const char readstr[] = "read";
48 static const char writestr[] = "write";
49 static const char timestr[] = "timeout";
50 static const char paritystr[] = "parity error";
51 static const char lanestat[][4] = { " OK", "BAD" };
52
53 const char *kind, *agent, *cycle, *event;
54 unsigned long address;
55
56 u32 mer = *kn02xa_mer;
57 u32 ear = *kn02xa_ear;
58 int action = MIPS_BE_FATAL;
59
60 /* Ack ASAP, so that any subsequent errors get caught. */
61 dec_kn02xa_be_ack();
62
63 kind = invoker ? intstr : excstr;
64
65 /* No DMA errors? */
66 agent = cpustr;
67
68 address = ear & KN02XA_EAR_ADDRESS;
69
70 /* Low 256MB is decoded as memory, high -- as TC. */
71 if (address < 0x10000000) {
72 cycle = mreadstr;
73 event = paritystr;
74 } else {
75 cycle = invoker ? writestr : readstr;
76 event = timestr;
77 }
78
79 if (is_fixup)
80 action = MIPS_BE_FIXUP;
81
82 if (action != MIPS_BE_FIXUP)
83 printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n",
84 kind, agent, cycle, event, address);
85
86 if (action != MIPS_BE_FIXUP && address < 0x10000000)
87 printk(KERN_ALERT " Byte lane status %#3x -- "
88 "#3: %s, #2: %s, #1: %s, #0: %s\n",
89 (mer & KN02XA_MER_BYTERR) >> 8,
90 lanestat[(mer & KN02XA_MER_BYTERR_3) != 0],
91 lanestat[(mer & KN02XA_MER_BYTERR_2) != 0],
92 lanestat[(mer & KN02XA_MER_BYTERR_1) != 0],
93 lanestat[(mer & KN02XA_MER_BYTERR_0) != 0]);
94
95 return action;
96 }
97
98 int dec_kn02xa_be_handler(struct pt_regs *regs, int is_fixup)
99 {
100 return dec_kn02xa_be_backend(regs, is_fixup, 0);
101 }
102
103 irqreturn_t dec_kn02xa_be_interrupt(int irq, void *dev_id)
104 {
105 struct pt_regs *regs = get_irq_regs();
106 int action = dec_kn02xa_be_backend(regs, 0, 1);
107
108 if (action == MIPS_BE_DISCARD)
109 return IRQ_HANDLED;
110
111 /*
112 * FIXME: Find the affected processes and kill them, otherwise
113 * we must die.
114 *
115 * The interrupt is asynchronously delivered thus EPC and RA
116 * may be irrelevant, but are printed for a reference.
117 */
118 printk(KERN_ALERT "Fatal bus interrupt, epc == %08lx, ra == %08lx\n",
119 regs->cp0_epc, regs->regs[31]);
120 die("Unrecoverable bus error", regs);
121 }
122
123
124 void __init dec_kn02xa_be_init(void)
125 {
126 volatile u32 *mbcs = (void *)CKSEG1ADDR(KN4K_SLOT_BASE + KN4K_MB_CSR);
127
128 /* For KN04 we need to make sure EE (?) is enabled in the MB. */
129 if (current_cpu_type() == CPU_R4000SC)
130 *mbcs |= KN4K_MB_CSR_EE;
131 fast_iob();
132
133 /* Clear any leftover errors from the firmware. */
134 dec_kn02xa_be_ack();
135 }
136
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