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 
dec_kn02xa_be_ack(void)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 
dec_kn02xa_be_backend(struct pt_regs * regs,int is_fixup,int invoker)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 
dec_kn02xa_be_handler(struct pt_regs * regs,int is_fixup)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 
dec_kn02xa_be_interrupt(int irq,void * dev_id)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 
dec_kn02xa_be_init(void)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