/* * Bus error event handling code for DECstation/DECsystem 3100 * and 2100 (KN01) systems equipped with parity error detection * logic. * * Copyright (c) 2005 Maciej W. Rozycki * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/init.h> #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/spinlock.h> #include <linux/types.h> #include <asm/inst.h> #include <asm/irq_regs.h> #include <asm/mipsregs.h> #include <asm/page.h> #include <asm/ptrace.h> #include <asm/system.h> #include <asm/traps.h> #include <asm/uaccess.h> #include <asm/dec/kn01.h> /* CP0 hazard avoidance. */ #define BARRIER \ __asm__ __volatile__( \ ".set push\n\t" \ ".set noreorder\n\t" \ "nop\n\t" \ ".set pop\n\t") /* * Bits 7:0 of the Control Register are write-only -- the * corresponding bits of the Status Register have a different * meaning. Hence we use a cache. It speeds up things a bit * as well. * * There is no default value -- it has to be initialized. */ u16 cached_kn01_csr; DEFINE_SPINLOCK(kn01_lock); static inline void dec_kn01_be_ack(void) { volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); unsigned long flags; spin_lock_irqsave(&kn01_lock, flags); *csr = cached_kn01_csr | KN01_CSR_MEMERR; /* Clear bus IRQ. */ iob(); spin_unlock_irqrestore(&kn01_lock, flags); } static int dec_kn01_be_backend(struct pt_regs *regs, int is_fixup, int invoker) { volatile u32 *kn01_erraddr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_ERRADDR); static const char excstr[] = "exception"; static const char intstr[] = "interrupt"; static const char cpustr[] = "CPU"; static const char mreadstr[] = "memory read"; static const char readstr[] = "read"; static const char writestr[] = "write"; static const char timestr[] = "timeout"; static const char paritystr[] = "parity error"; int data = regs->cp0_cause & 4; unsigned int __user *pc = (unsigned int __user *)regs->cp0_epc + ((regs->cp0_cause & CAUSEF_BD) != 0); union mips_instruction insn; unsigned long entrylo, offset; long asid, entryhi, vaddr; const char *kind, *agent, *cycle, *event; unsigned long address; u32 erraddr = *kn01_erraddr; int action = MIPS_BE_FATAL; /* Ack ASAP, so that any subsequent errors get caught. */ dec_kn01_be_ack(); kind = invoker ? intstr : excstr; agent = cpustr; if (invoker) address = erraddr; else { /* Bloody hardware doesn't record the address for reads... */ if (data) { /* This never faults. */ __get_user(insn.word, pc); vaddr = regs->regs[insn.i_format.rs] + insn.i_format.simmediate; } else vaddr = (long)pc; if (KSEGX(vaddr) == CKSEG0 || KSEGX(vaddr) == CKSEG1) address = CPHYSADDR(vaddr); else { /* Peek at what physical address the CPU used. */ asid = read_c0_entryhi(); entryhi = asid & (PAGE_SIZE - 1); entryhi |= vaddr & ~(PAGE_SIZE - 1); write_c0_entryhi(entryhi); BARRIER; tlb_probe(); /* No need to check for presence. */ tlb_read(); entrylo = read_c0_entrylo0(); write_c0_entryhi(asid); offset = vaddr & (PAGE_SIZE - 1); address = (entrylo & ~(PAGE_SIZE - 1)) | offset; } } /* Treat low 256MB as memory, high -- as I/O. */ if (address < 0x10000000) { cycle = mreadstr; event = paritystr; } else { cycle = invoker ? writestr : readstr; event = timestr; } if (is_fixup) action = MIPS_BE_FIXUP; if (action != MIPS_BE_FIXUP) printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n", kind, agent, cycle, event, address); return action; } int dec_kn01_be_handler(struct pt_regs *regs, int is_fixup) { return dec_kn01_be_backend(regs, is_fixup, 0); } irqreturn_t dec_kn01_be_interrupt(int irq, void *dev_id) { volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); struct pt_regs *regs = get_irq_regs(); int action; if (!(*csr & KN01_CSR_MEMERR)) return IRQ_NONE; /* Must have been video. */ action = dec_kn01_be_backend(regs, 0, 1); if (action == MIPS_BE_DISCARD) return IRQ_HANDLED; /* * FIXME: Find the affected processes and kill them, otherwise * we must die. * * The interrupt is asynchronously delivered thus EPC and RA * may be irrelevant, but are printed for a reference. */ printk(KERN_ALERT "Fatal bus interrupt, epc == %08lx, ra == %08lx\n", regs->cp0_epc, regs->regs[31]); die("Unrecoverable bus error", regs); } void __init dec_kn01_be_init(void) { volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); unsigned long flags; spin_lock_irqsave(&kn01_lock, flags); /* Preset write-only bits of the Control Register cache. */ cached_kn01_csr = *csr; cached_kn01_csr &= KN01_CSR_STATUS | KN01_CSR_PARDIS | KN01_CSR_TXDIS; cached_kn01_csr |= KN01_CSR_LEDS; /* Enable parity error detection. */ cached_kn01_csr &= ~KN01_CSR_PARDIS; *csr = cached_kn01_csr; iob(); spin_unlock_irqrestore(&kn01_lock, flags); /* Clear any leftover errors from the firmware. */ dec_kn01_be_ack(); }