arch/mips/dec/kn01-berr.c

   1 /*
   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>
  21 #include <asm/irq_regs.h>
  22 #include <asm/mipsregs.h>
  23 #include <asm/page.h>
  24 #include <asm/ptrace.h>
  25 #include <asm/traps.h>
  26 #include <linux/uaccess.h>
  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;
  48 static DEFINE_RAW_SPINLOCK(kn01_lock);
  49
  50
  51 static inline void dec_kn01_be_ack(void)
  52 {
  53         volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR);
  54         unsigned long flags;
  55
  56         raw_spin_lock_irqsave(&kn01_lock, flags);
  57
  58         *csr = cached_kn01_csr | KN01_CSR_MEMERR;       /* Clear bus IRQ. */
  59         iob();
  60
  61         raw_spin_unlock_irqrestore(&kn01_lock, flags);
  62 }
  63
  64 static int dec_kn01_be_backend(struct pt_regs *regs, int is_fixup, int invoker)
  65 {
  66         volatile u32 *kn01_erraddr = (void *)CKSEG1ADDR(KN01_SLOT_BASE +
  67                                                         KN01_ERRADDR);
  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
 152 irqreturn_t dec_kn01_be_interrupt(int irq, void *dev_id)
 153 {
 154         volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR);
 155         struct pt_regs *regs = get_irq_regs();
 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 {
 181         volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR);
 182         unsigned long flags;
 183
 184         raw_spin_lock_irqsave(&kn01_lock, flags);
 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
 196         raw_spin_unlock_irqrestore(&kn01_lock, flags);
 197
 198         /* Clear any leftover errors from the firmware. */
 199         dec_kn01_be_ack();
 200 }