diff options
Diffstat (limited to 'arch/mips/dec/kn01-berr.c')
| -rw-r--r-- | arch/mips/dec/kn01-berr.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/arch/mips/dec/kn01-berr.c b/arch/mips/dec/kn01-berr.c new file mode 100644 index 0000000000..76efed7bc9 --- /dev/null +++ b/arch/mips/dec/kn01-berr.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 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 + */ + +#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/traps.h> +#include <linux/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; +static DEFINE_RAW_SPINLOCK(kn01_lock); + + +static inline void dec_kn01_be_ack(void) +{ + volatile u16 *csr = (void *)CKSEG1ADDR(KN01_SLOT_BASE + KN01_CSR); + unsigned long flags; + + raw_spin_lock_irqsave(&kn01_lock, flags); + + *csr = cached_kn01_csr | KN01_CSR_MEMERR; /* Clear bus IRQ. */ + iob(); + + raw_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; + + raw_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(); + + raw_spin_unlock_irqrestore(&kn01_lock, flags); + + /* Clear any leftover errors from the firmware. */ + dec_kn01_be_ack(); +} |