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