arch/mips/dec/kn01-berr.c

   1 /*
   2  *      linux/arch/mips/dec/kn01-berr.c
   3  *
   4  *      Bus error event handling code for DECstation/DECsystem 3100
   5  *      and 2100 (KN01) systems equipped with parity error detection
   6  *      logic.
   7  *
   8  *      Copyright (c) 2005  Maciej W. Rozycki
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/kernel.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/types.h>
  21
  22 #include <asm/inst.h>
  23 #include <asm/irq_regs.h>
  24 #include <asm/mipsregs.h>
  25 #include <asm/page.h>
  26 #include <asm/ptrace.h>
  27 #include <asm/system.h>
  28 #include <asm/traps.h>
  29 #include <asm/uaccess.h>
  30
  31 #include <asm/dec/kn01.h>
  32
  33
  34 /* CP0 hazard avoidance. */
  35 #define BARRIER                         \
  36         __asm__ __volatile__(           \
  37                 ".set   push\n\t"       \
  38                 ".set   noreorder\n\t"  \
  39                 "nop\n\t"               \
  40                 ".set   pop\n\t")
  41
  42 /*
  43  * Bits 7:0 of the Control Register are write-only -- the
  44  * corresponding bits of the Status Register have a different
  45  * meaning.  Hence we use a cache.  It speeds up things a bit
  46  * as well.
  47  *
  48  * There is no default value -- it has to be initialized.
  49  */
  50 u16 cached_kn01_csr;
  51 DEFINE_SPINLOCK(kn01_lock);
  52
  53
  54 static inline void dec_kn01_be_ack(void)
  55 {
  56         volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR);
  57         unsigned long flags;
  58
  59         spin_lock_irqsave(&kn01_lock, flags);
  60
  61         *csr = cached_kn01_csr | KN01_CSR_MEMERR;       /* Clear bus IRQ. */
  62         iob();
  63
  64         spin_unlock_irqrestore(&kn01_lock, flags);
  65 }
  66
  67 static int dec_kn01_be_backend(struct pt_regs *regs, int is_fixup, int invoker)
  68 {
  69         volatile u32 *kn01_erraddr = (void *)CKSEG1ADDR(KN01_SLOT_BASE +
  70                                                         KN01_ERRADDR);
  71
  72         static const char excstr[] = "exception";
  73         static const char intstr[] = "interrupt";
  74         static const char cpustr[] = "CPU";
  75         static const char mreadstr[] = "memory read";
  76         static const char readstr[] = "read";
  77         static const char writestr[] = "write";
  78         static const char timestr[] = "timeout";
  79         static const char paritystr[] = "parity error";
  80
  81         int data = regs->cp0_cause & 4;
  82         unsigned int __user *pc = (unsigned int __user *)regs->cp0_epc +
  83                                   ((regs->cp0_cause & CAUSEF_BD) != 0);
  84         union mips_instruction insn;
  85         unsigned long entrylo, offset;
  86         long asid, entryhi, vaddr;
  87
  88         const char *kind, *agent, *cycle, *event;
  89         unsigned long address;
  90
  91         u32 erraddr = *kn01_erraddr;
  92         int action = MIPS_BE_FATAL;
  93
  94         /* Ack ASAP, so that any subsequent errors get caught. */
  95         dec_kn01_be_ack();
  96
  97         kind = invoker ? intstr : excstr;
  98
  99         agent = cpustr;
 100
 101         if (invoker)
 102                 address = erraddr;
 103         else {
 104                 /* Bloody hardware doesn't record the address for reads... */
 105                 if (data) {
 106                         /* This never faults. */
 107                         __get_user(insn.word, pc);
 108                         vaddr = regs->regs[insn.i_format.rs] +
 109                                 insn.i_format.simmediate;
 110                 } else
 111                         vaddr = (long)pc;
 112                 if (KSEGX(vaddr) == CKSEG0 || KSEGX(vaddr) == CKSEG1)
 113                         address = CPHYSADDR(vaddr);
 114                 else {
 115                         /* Peek at what physical address the CPU used. */
 116                         asid = read_c0_entryhi();
 117                         entryhi = asid & (PAGE_SIZE - 1);
 118                         entryhi |= vaddr & ~(PAGE_SIZE - 1);
 119                         write_c0_entryhi(entryhi);
 120                         BARRIER;
 121                         tlb_probe();
 122                         /* No need to check for presence. */
 123                         tlb_read();
 124                         entrylo = read_c0_entrylo0();
 125                         write_c0_entryhi(asid);
 126                         offset = vaddr & (PAGE_SIZE - 1);
 127                         address = (entrylo & ~(PAGE_SIZE - 1)) | offset;
 128                 }
 129         }
 130
 131         /* Treat low 256MB as memory, high -- as I/O. */
 132         if (address < 0x10000000) {
 133                 cycle = mreadstr;
 134                 event = paritystr;
 135         } else {
 136                 cycle = invoker ? writestr : readstr;
 137                 event = timestr;
 138         }
 139
 140         if (is_fixup)
 141                 action = MIPS_BE_FIXUP;
 142
 143         if (action != MIPS_BE_FIXUP)
 144                 printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n",
 145                         kind, agent, cycle, event, address);
 146
 147         return action;
 148 }
 149
 150 int dec_kn01_be_handler(struct pt_regs *regs, int is_fixup)
 151 {
 152         return dec_kn01_be_backend(regs, is_fixup, 0);
 153 }
 154
 155 irqreturn_t dec_kn01_be_interrupt(int irq, void *dev_id)
 156 {
 157         volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR);
 158         struct pt_regs *regs = get_irq_regs();
 159         int action;
 160
 161         if (!(*csr & KN01_CSR_MEMERR))
 162                 return IRQ_NONE;                /* Must have been video. */
 163
 164         action = dec_kn01_be_backend(regs, 0, 1);
 165
 166         if (action == MIPS_BE_DISCARD)
 167                 return IRQ_HANDLED;
 168
 169         /*
 170          * FIXME: Find the affected processes and kill them, otherwise
 171          * we must die.
 172          *
 173          * The interrupt is asynchronously delivered thus EPC and RA
 174          * may be irrelevant, but are printed for a reference.
 175          */
 176         printk(KERN_ALERT "Fatal bus interrupt, epc == %08lx, ra == %08lx\n",
 177                regs->cp0_epc, regs->regs[31]);
 178         die("Unrecoverable bus error", regs);
 179 }
 180
 181
 182 void __init dec_kn01_be_init(void)
 183 {
 184         volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR);
 185         unsigned long flags;
 186
 187         spin_lock_irqsave(&kn01_lock, flags);
 188
 189         /* Preset write-only bits of the Control Register cache. */
 190         cached_kn01_csr = *csr;
 191         cached_kn01_csr &= KN01_CSR_STATUS | KN01_CSR_PARDIS | KN01_CSR_TXDIS;
 192         cached_kn01_csr |= KN01_CSR_LEDS;
 193
 194         /* Enable parity error detection. */
 195         cached_kn01_csr &= ~KN01_CSR_PARDIS;
 196         *csr = cached_kn01_csr;
 197         iob();
 198
 199         spin_unlock_irqrestore(&kn01_lock, flags);
 200
 201         /* Clear any leftover errors from the firmware. */
 202         dec_kn01_be_ack();
 203 }