Actual handlers for bus errors for Pmax and 3min.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/dec/kn01-berr.c b/arch/mips/dec/kn01-berr.c
new file mode 100644

1 files changed, 200 insertions, 0 deletions

diff --git a/arch/mips/dec/kn01-berr.c b/arch/mips/dec/kn01-berr.c
new file mode 100644
index 000000000000..8ec7b30a90c1
--- /dev/null
+++ b/arch/mips/dec/kn01-berr.c
@@ -0,0 +1,200 @@
+/*
+ *	linux/arch/mips/dec/kn01-berr.c
+ *
+ *	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/mipsregs.h>
+#include <asm/page.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 *)(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 *)(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,
+				    struct pt_regs *regs)
+{
+	volatile u16 *csr = (void *)(KN01_SLOT_BASE + KN01_CSR);
+	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 *)(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();
+}