[MIPS] IP28 support

Add support for SGI IP28 machines (Indigo 2 with R10k CPUs)
This work is mainly based on Peter Fuersts work.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 511 insertions, 3 deletions

diff --git a/arch/mips/sgi-ip22/Makefile b/arch/mips/sgi-ip22/Makefile
index e3acb51b70b..ef1564e40c8 100644
--- a/arch/mips/sgi-ip22/Makefile
+++ b/arch/mips/sgi-ip22/Makefile
@@ -3,9 +3,11 @@
 # under Linux.
 #
 
-obj-y	+= ip22-mc.o ip22-hpc.o ip22-int.o ip22-berr.o \
-	   ip22-time.o ip22-nvram.o ip22-platform.o ip22-reset.o ip22-setup.o
+obj-y	+= ip22-mc.o ip22-hpc.o ip22-int.o ip22-time.o ip22-nvram.o \
+	   ip22-platform.o ip22-reset.o ip22-setup.o
 
+obj-$(CONFIG_SGI_IP22) += ip22-berr.o
+obj-$(CONFIG_SGI_IP28) += ip28-berr.o
 obj-$(CONFIG_EISA)	+= ip22-eisa.o
 
-EXTRA_CFLAGS += -Werror
+# EXTRA_CFLAGS += -Werror
diff --git a/arch/mips/sgi-ip22/ip22-mc.c b/arch/mips/sgi-ip22/ip22-mc.c
index 01a805dcc67..3f35d6367be 100644
--- a/arch/mips/sgi-ip22/ip22-mc.c
+++ b/arch/mips/sgi-ip22/ip22-mc.c
@@ -4,6 +4,7 @@
  * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com)
  * Copyright (C) 1999 Andrew R. Baker (andrewb@uab.edu) - Indigo2 changes
  * Copyright (C) 2003 Ladislav Michl  (ladis@linux-mips.org)
+ * Copyright (C) 2004 Peter Fuerst    (pf@net.alphadv.de) - IP28
  */
 
 #include <linux/init.h>
@@ -137,9 +138,12 @@ void __init sgimc_init(void)
 	/* Step 2: Enable all parity checking in cpu control register
 	 *         zero.
 	 */
+	/* don't touch parity settings for IP28 */
+#ifndef CONFIG_SGI_IP28
 	tmp = sgimc->cpuctrl0;
 	tmp |= (SGIMC_CCTRL0_EPERRGIO | SGIMC_CCTRL0_EPERRMEM |
 		SGIMC_CCTRL0_R4KNOCHKPARR);
+#endif
 	sgimc->cpuctrl0 = tmp;
 
 	/* Step 3: Setup the MC write buffer depth, this is controlled
diff --git a/arch/mips/sgi-ip22/ip28-berr.c b/arch/mips/sgi-ip22/ip28-berr.c
new file mode 100644
index 00000000000..30e12e2ec4b
--- /dev/null
+++ b/arch/mips/sgi-ip22/ip28-berr.c
@@ -0,0 +1,502 @@
+/*
+ * ip28-berr.c: Bus error handling.
+ *
+ * Copyright (C) 2002, 2003 Ladislav Michl (ladis@linux-mips.org)
+ * Copyright (C) 2005 Peter Fuerst (pf@net.alphadv.de) - IP28
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+
+#include <asm/addrspace.h>
+#include <asm/system.h>
+#include <asm/traps.h>
+#include <asm/branch.h>
+#include <asm/irq_regs.h>
+#include <asm/sgi/mc.h>
+#include <asm/sgi/hpc3.h>
+#include <asm/sgi/ioc.h>
+#include <asm/sgi/ip22.h>
+#include <asm/r4kcache.h>
+#include <asm/uaccess.h>
+#include <asm/bootinfo.h>
+
+static unsigned int count_be_is_fixup;
+static unsigned int count_be_handler;
+static unsigned int count_be_interrupt;
+static int debug_be_interrupt;
+
+static unsigned int cpu_err_stat;	/* Status reg for CPU */
+static unsigned int gio_err_stat;	/* Status reg for GIO */
+static unsigned int cpu_err_addr;	/* Error address reg for CPU */
+static unsigned int gio_err_addr;	/* Error address reg for GIO */
+static unsigned int extio_stat;
+static unsigned int hpc3_berr_stat;	/* Bus error interrupt status */
+
+struct hpc3_stat {
+	unsigned long addr;
+	unsigned int ctrl;
+	unsigned int cbp;
+	unsigned int ndptr;
+};
+
+static struct {
+	struct hpc3_stat pbdma[8];
+	struct hpc3_stat scsi[2];
+	struct hpc3_stat ethrx, ethtx;
+} hpc3;
+
+static struct {
+	unsigned long err_addr;
+	struct {
+		u32 lo;
+		u32 hi;
+	} tags[1][2], tagd[4][2], tagi[4][2]; /* Way 0/1 */
+} cache_tags;
+
+static inline void save_cache_tags(unsigned busaddr)
+{
+	unsigned long addr = CAC_BASE | busaddr;
+	int i;
+	cache_tags.err_addr = addr;
+
+	/*
+	 * Starting with a bus-address, save secondary cache (indexed by
+	 * PA[23..18:7..6]) tags first.
+	 */
+	addr &= ~1L;
+#define tag cache_tags.tags[0]
+	cache_op(Index_Load_Tag_S, addr);
+	tag[0].lo = read_c0_taglo();	/* PA[35:18], VA[13:12] */
+	tag[0].hi = read_c0_taghi();	/* PA[39:36] */
+	cache_op(Index_Load_Tag_S, addr | 1L);
+	tag[1].lo = read_c0_taglo();	/* PA[35:18], VA[13:12] */
+	tag[1].hi = read_c0_taghi();	/* PA[39:36] */
+#undef tag
+
+	/*
+	 * Save all primary data cache (indexed by VA[13:5]) tags which
+	 * might fit to this bus-address, knowing that VA[11:0] == PA[11:0].
+	 * Saving all tags and evaluating them later is easier and safer
+	 * than relying on VA[13:12] from the secondary cache tags to pick
+	 * matching primary tags here already.
+	 */
+	addr &= (0xffL << 56) | ((1 << 12) - 1);
+#define tag cache_tags.tagd[i]
+	for (i = 0; i < 4; ++i, addr += (1 << 12)) {
+		cache_op(Index_Load_Tag_D, addr);
+		tag[0].lo = read_c0_taglo();	/* PA[35:12] */
+		tag[0].hi = read_c0_taghi();	/* PA[39:36] */
+		cache_op(Index_Load_Tag_D, addr | 1L);
+		tag[1].lo = read_c0_taglo();	/* PA[35:12] */
+		tag[1].hi = read_c0_taghi();	/* PA[39:36] */
+	}
+#undef tag
+
+	/*
+	 * Save primary instruction cache (indexed by VA[13:6]) tags
+	 * the same way.
+	 */
+	addr &= (0xffL << 56) | ((1 << 12) - 1);
+#define tag cache_tags.tagi[i]
+	for (i = 0; i < 4; ++i, addr += (1 << 12)) {
+		cache_op(Index_Load_Tag_I, addr);
+		tag[0].lo = read_c0_taglo();	/* PA[35:12] */
+		tag[0].hi = read_c0_taghi();	/* PA[39:36] */
+		cache_op(Index_Load_Tag_I, addr | 1L);
+		tag[1].lo = read_c0_taglo();	/* PA[35:12] */
+		tag[1].hi = read_c0_taghi();	/* PA[39:36] */
+	}
+#undef tag
+}
+
+#define GIO_ERRMASK	0xff00
+#define CPU_ERRMASK	0x3f00
+
+static void save_and_clear_buserr(void)
+{
+	int i;
+
+	/* save status registers */
+	cpu_err_addr = sgimc->cerr;
+	cpu_err_stat = sgimc->cstat;
+	gio_err_addr = sgimc->gerr;
+	gio_err_stat = sgimc->gstat;
+	extio_stat = sgioc->extio;
+	hpc3_berr_stat = hpc3c0->bestat;
+
+	hpc3.scsi[0].addr  = (unsigned long)&hpc3c0->scsi_chan0;
+	hpc3.scsi[0].ctrl  = hpc3c0->scsi_chan0.ctrl; /* HPC3_SCTRL_ACTIVE ? */
+	hpc3.scsi[0].cbp   = hpc3c0->scsi_chan0.cbptr;
+	hpc3.scsi[0].ndptr = hpc3c0->scsi_chan0.ndptr;
+
+	hpc3.scsi[1].addr  = (unsigned long)&hpc3c0->scsi_chan1;
+	hpc3.scsi[1].ctrl  = hpc3c0->scsi_chan1.ctrl; /* HPC3_SCTRL_ACTIVE ? */
+	hpc3.scsi[1].cbp   = hpc3c0->scsi_chan1.cbptr;
+	hpc3.scsi[1].ndptr = hpc3c0->scsi_chan1.ndptr;
+
+	hpc3.ethrx.addr  = (unsigned long)&hpc3c0->ethregs.rx_cbptr;
+	hpc3.ethrx.ctrl  = hpc3c0->ethregs.rx_ctrl; /* HPC3_ERXCTRL_ACTIVE ? */
+	hpc3.ethrx.cbp   = hpc3c0->ethregs.rx_cbptr;
+	hpc3.ethrx.ndptr = hpc3c0->ethregs.rx_ndptr;
+
+	hpc3.ethtx.addr  = (unsigned long)&hpc3c0->ethregs.tx_cbptr;
+	hpc3.ethtx.ctrl  = hpc3c0->ethregs.tx_ctrl; /* HPC3_ETXCTRL_ACTIVE ? */
+	hpc3.ethtx.cbp   = hpc3c0->ethregs.tx_cbptr;
+	hpc3.ethtx.ndptr = hpc3c0->ethregs.tx_ndptr;
+
+	for (i = 0; i < 8; ++i) {
+		/* HPC3_PDMACTRL_ISACT ? */
+		hpc3.pbdma[i].addr  = (unsigned long)&hpc3c0->pbdma[i];
+		hpc3.pbdma[i].ctrl  = hpc3c0->pbdma[i].pbdma_ctrl;
+		hpc3.pbdma[i].cbp   = hpc3c0->pbdma[i].pbdma_bptr;
+		hpc3.pbdma[i].ndptr = hpc3c0->pbdma[i].pbdma_dptr;
+	}
+	i = 0;
+	if (gio_err_stat & CPU_ERRMASK)
+		i = gio_err_addr;
+	if (cpu_err_stat & CPU_ERRMASK)
+		i = cpu_err_addr;
+	save_cache_tags(i);
+
+	sgimc->cstat = sgimc->gstat = 0;
+}
+
+static void print_cache_tags(void)
+{
+	u32 scb, scw;
+	int i;
+
+	printk(KERN_ERR "Cache tags @ %08x:\n", (unsigned)cache_tags.err_addr);
+
+	/* PA[31:12] shifted to PTag0 (PA[35:12]) format */
+	scw = (cache_tags.err_addr >> 4) & 0x0fffff00;
+
+	scb = cache_tags.err_addr & ((1 << 12) - 1) & ~((1 << 5) - 1);
+	for (i = 0; i < 4; ++i) { /* for each possible VA[13:12] value */
+		if ((cache_tags.tagd[i][0].lo & 0x0fffff00) != scw &&
+		    (cache_tags.tagd[i][1].lo & 0x0fffff00) != scw)
+		    continue;
+		printk(KERN_ERR
+		       "D: 0: %08x %08x, 1: %08x %08x  (VA[13:5]  %04x)\n",
+			cache_tags.tagd[i][0].hi, cache_tags.tagd[i][0].lo,
+			cache_tags.tagd[i][1].hi, cache_tags.tagd[i][1].lo,
+			scb | (1 << 12)*i);
+	}
+	scb = cache_tags.err_addr & ((1 << 12) - 1) & ~((1 << 6) - 1);
+	for (i = 0; i < 4; ++i) { /* for each possible VA[13:12] value */
+		if ((cache_tags.tagi[i][0].lo & 0x0fffff00) != scw &&
+		    (cache_tags.tagi[i][1].lo & 0x0fffff00) != scw)
+		    continue;
+		printk(KERN_ERR
+		       "I: 0: %08x %08x, 1: %08x %08x  (VA[13:6]  %04x)\n",
+			cache_tags.tagi[i][0].hi, cache_tags.tagi[i][0].lo,
+			cache_tags.tagi[i][1].hi, cache_tags.tagi[i][1].lo,
+			scb | (1 << 12)*i);
+	}
+	i = read_c0_config();
+	scb = i & (1 << 13) ? 7:6;      /* scblksize = 2^[7..6] */
+	scw = ((i >> 16) & 7) + 19 - 1; /* scwaysize = 2^[24..19] / 2 */
+
+	i = ((1 << scw) - 1) & ~((1 << scb) - 1);
+	printk(KERN_ERR "S: 0: %08x %08x, 1: %08x %08x  (PA[%u:%u] %05x)\n",
+		cache_tags.tags[0][0].hi, cache_tags.tags[0][0].lo,
+		cache_tags.tags[0][1].hi, cache_tags.tags[0][1].lo,
+		scw-1, scb, i & (unsigned)cache_tags.err_addr);
+}
+
+static inline const char *cause_excode_text(int cause)
+{
+	static const char *txt[32] =
+	{	"Interrupt",
+		"TLB modification",
+		"TLB (load or instruction fetch)",
+		"TLB (store)",
+		"Address error (load or instruction fetch)",
+		"Address error (store)",
+		"Bus error (instruction fetch)",
+		"Bus error (data: load or store)",
+		"Syscall",
+		"Breakpoint",
+		"Reserved instruction",
+		"Coprocessor unusable",
+		"Arithmetic Overflow",
+		"Trap",
+		"14",
+		"Floating-Point",
+		"16", "17", "18", "19", "20", "21", "22",
+		"Watch Hi/Lo",
+		"24", "25", "26", "27", "28", "29", "30", "31",
+	};
+	return txt[(cause & 0x7c) >> 2];
+}
+
+static void print_buserr(const struct pt_regs *regs)
+{
+	const int field = 2 * sizeof(unsigned long);
+	int error = 0;
+
+	if (extio_stat & EXTIO_MC_BUSERR) {
+		printk(KERN_ERR "MC Bus Error\n");
+		error |= 1;
+	}
+	if (extio_stat & EXTIO_HPC3_BUSERR) {
+		printk(KERN_ERR "HPC3 Bus Error 0x%x:<id=0x%x,%s,lane=0x%x>\n",
+			hpc3_berr_stat,
+			(hpc3_berr_stat & HPC3_BESTAT_PIDMASK) >>
+					  HPC3_BESTAT_PIDSHIFT,
+			(hpc3_berr_stat & HPC3_BESTAT_CTYPE) ? "PIO" : "DMA",
+			hpc3_berr_stat & HPC3_BESTAT_BLMASK);
+		error |= 2;
+	}
+	if (extio_stat & EXTIO_EISA_BUSERR) {
+		printk(KERN_ERR "EISA Bus Error\n");
+		error |= 4;
+	}
+	if (cpu_err_stat & CPU_ERRMASK) {
+		printk(KERN_ERR "CPU error 0x%x<%s%s%s%s%s%s> @ 0x%08x\n",
+			cpu_err_stat,
+			cpu_err_stat & SGIMC_CSTAT_RD ? "RD " : "",
+			cpu_err_stat & SGIMC_CSTAT_PAR ? "PAR " : "",
+			cpu_err_stat & SGIMC_CSTAT_ADDR ? "ADDR " : "",
+			cpu_err_stat & SGIMC_CSTAT_SYSAD_PAR ? "SYSAD " : "",
+			cpu_err_stat & SGIMC_CSTAT_SYSCMD_PAR ? "SYSCMD " : "",
+			cpu_err_stat & SGIMC_CSTAT_BAD_DATA ? "BAD_DATA " : "",
+			cpu_err_addr);
+		error |= 8;
+	}
+	if (gio_err_stat & GIO_ERRMASK) {
+		printk(KERN_ERR "GIO error 0x%x:<%s%s%s%s%s%s%s%s> @ 0x%08x\n",
+			gio_err_stat,
+			gio_err_stat & SGIMC_GSTAT_RD ? "RD " : "",
+			gio_err_stat & SGIMC_GSTAT_WR ? "WR " : "",
+			gio_err_stat & SGIMC_GSTAT_TIME ? "TIME " : "",
+			gio_err_stat & SGIMC_GSTAT_PROM ? "PROM " : "",
+			gio_err_stat & SGIMC_GSTAT_ADDR ? "ADDR " : "",
+			gio_err_stat & SGIMC_GSTAT_BC ? "BC " : "",
+			gio_err_stat & SGIMC_GSTAT_PIO_RD ? "PIO_RD " : "",
+			gio_err_stat & SGIMC_GSTAT_PIO_WR ? "PIO_WR " : "",
+			gio_err_addr);
+		error |= 16;
+	}
+	if (!error)
+		printk(KERN_ERR "MC: Hmm, didn't find any error condition.\n");
+	else {
+		printk(KERN_ERR "CP0: config %08x,  "
+			"MC: cpuctrl0/1: %08x/%05x, giopar: %04x\n"
+			"MC: cpu/gio_memacc: %08x/%05x, memcfg0/1: %08x/%08x\n",
+			read_c0_config(),
+			sgimc->cpuctrl0, sgimc->cpuctrl0, sgimc->giopar,
+			sgimc->cmacc, sgimc->gmacc,
+			sgimc->mconfig0, sgimc->mconfig1);
+		print_cache_tags();
+	}
+	printk(KERN_ALERT "%s, epc == %0*lx, ra == %0*lx\n",
+	       cause_excode_text(regs->cp0_cause),
+	       field, regs->cp0_epc, field, regs->regs[31]);
+}
+
+/*
+ * Check, whether MC's (virtual) DMA address caused the bus error.
+ * See "Virtual DMA Specification", Draft 1.5, Feb 13 1992, SGI
+ */
+
+static int addr_is_ram(unsigned long addr, unsigned sz)
+{
+	int i;
+
+	for (i = 0; i < boot_mem_map.nr_map; i++) {
+		unsigned long a = boot_mem_map.map[i].addr;
+		if (a <= addr && addr+sz <= a+boot_mem_map.map[i].size)
+			return 1;
+	}
+	return 0;
+}
+
+static int check_microtlb(u32 hi, u32 lo, unsigned long vaddr)
+{
+	/* This is likely rather similar to correct code ;-) */
+
+	vaddr &= 0x7fffffff; /* Doc. states that top bit is ignored */
+
+	/* If tlb-entry is valid and VPN-high (bits [30:21] ?) matches... */
+	if ((lo & 2) && (vaddr >> 21) == ((hi<<1) >> 22)) {
+		u32 ctl = sgimc->dma_ctrl;
+		if (ctl & 1) {
+			unsigned int pgsz = (ctl & 2) ? 14:12; /* 16k:4k */
+			/* PTEIndex is VPN-low (bits [22:14]/[20:12] ?) */
+			unsigned long pte = (lo >> 6) << 12; /* PTEBase */
+			pte += 8*((vaddr >> pgsz) & 0x1ff);
+			if (addr_is_ram(pte, 8)) {
+				/*
+				 * Note: Since DMA hardware does look up
+				 * translation on its own, this PTE *must*
+				 * match the TLB/EntryLo-register format !
+				 */
+				unsigned long a = *(unsigned long *)
+						PHYS_TO_XKSEG_UNCACHED(pte);
+				a = (a & 0x3f) << 6; /* PFN */
+				a += vaddr & ((1 << pgsz) - 1);
+				return (cpu_err_addr == a);
+			}
+		}
+	}
+	return 0;
+}
+
+static int check_vdma_memaddr(void)
+{
+	if (cpu_err_stat & CPU_ERRMASK) {
+		u32 a = sgimc->maddronly;
+
+		if (!(sgimc->dma_ctrl & 0x100)) /* Xlate-bit clear ? */
+			return (cpu_err_addr == a);
+
+		if (check_microtlb(sgimc->dtlb_hi0, sgimc->dtlb_lo0, a) ||
+		    check_microtlb(sgimc->dtlb_hi1, sgimc->dtlb_lo1, a) ||
+		    check_microtlb(sgimc->dtlb_hi2, sgimc->dtlb_lo2, a) ||
+		    check_microtlb(sgimc->dtlb_hi3, sgimc->dtlb_lo3, a))
+			return 1;
+	}
+	return 0;
+}
+
+static int check_vdma_gioaddr(void)
+{
+	if (gio_err_stat & GIO_ERRMASK) {
+		u32 a = sgimc->gio_dma_trans;
+		a = (sgimc->gmaddronly & ~a) | (sgimc->gio_dma_sbits & a);
+		return (gio_err_addr == a);
+	}
+	return 0;
+}
+
+/*
+ * MC sends an interrupt whenever bus or parity errors occur. In addition,
+ * if the error happened during a CPU read, it also asserts the bus error
+ * pin on the R4K. Code in bus error handler save the MC bus error registers
+ * and then clear the interrupt when this happens.
+ */
+
+static int ip28_be_interrupt(const struct pt_regs *regs)
+{
+	int i;
+
+	save_and_clear_buserr();
+	/*
+	 * Try to find out, whether we got here by a mispredicted speculative
+	 * load/store operation.  If so, it's not fatal, we can go on.
+	 */
+	/* Any cause other than "Interrupt" (ExcCode 0) is fatal. */
+	if (regs->cp0_cause & CAUSEF_EXCCODE)
+		goto mips_be_fatal;
+
+	/* Any cause other than "Bus error interrupt" (IP6) is weird. */
+	if ((regs->cp0_cause & CAUSEF_IP6) != CAUSEF_IP6)
+		goto mips_be_fatal;
+
+	if (extio_stat & (EXTIO_HPC3_BUSERR | EXTIO_EISA_BUSERR))
+		goto mips_be_fatal;
+
+	/* Any state other than "Memory bus error" is fatal. */
+	if (cpu_err_stat & CPU_ERRMASK & ~SGIMC_CSTAT_ADDR)
+		goto mips_be_fatal;
+
+	/* GIO errors other than timeouts are fatal */
+	if (gio_err_stat & GIO_ERRMASK & ~SGIMC_GSTAT_TIME)
+		goto mips_be_fatal;
+
+	/*
+	 * Now we have an asynchronous bus error, speculatively or DMA caused.
+	 * Need to search all DMA descriptors for the error address.
+	 */
+	for (i = 0; i < sizeof(hpc3)/sizeof(struct hpc3_stat); ++i) {
+		struct hpc3_stat *hp = (struct hpc3_stat *)&hpc3 + i;
+		if ((cpu_err_stat & CPU_ERRMASK) &&
+		    (cpu_err_addr == hp->ndptr || cpu_err_addr == hp->cbp))
+			break;
+		if ((gio_err_stat & GIO_ERRMASK) &&
+		    (gio_err_addr == hp->ndptr || gio_err_addr == hp->cbp))
+			break;
+	}
+	if (i < sizeof(hpc3)/sizeof(struct hpc3_stat)) {
+		struct hpc3_stat *hp = (struct hpc3_stat *)&hpc3 + i;
+		printk(KERN_ERR "at DMA addresses: HPC3 @ %08lx:"
+		       " ctl %08x, ndp %08x, cbp %08x\n",
+		       CPHYSADDR(hp->addr), hp->ctrl, hp->ndptr, hp->cbp);
+		goto mips_be_fatal;
+	}
+	/* Check MC's virtual DMA stuff. */
+	if (check_vdma_memaddr()) {
+		printk(KERN_ERR "at GIO DMA: mem address 0x%08x.\n",
+			sgimc->maddronly);
+		goto mips_be_fatal;
+	}
+	if (check_vdma_gioaddr()) {
+		printk(KERN_ERR "at GIO DMA: gio address 0x%08x.\n",
+			sgimc->gmaddronly);
+		goto mips_be_fatal;
+	}
+	/* A speculative bus error... */
+	if (debug_be_interrupt) {
+		print_buserr(regs);
+		printk(KERN_ERR "discarded!\n");
+	}
+	return MIPS_BE_DISCARD;
+
+mips_be_fatal:
+	print_buserr(regs);
+	return MIPS_BE_FATAL;
+}
+
+void ip22_be_interrupt(int irq)
+{
+	const struct pt_regs *regs = get_irq_regs();
+
+	count_be_interrupt++;
+
+	if (ip28_be_interrupt(regs) != MIPS_BE_DISCARD) {
+		/* Assume it would be too dangerous to continue ... */
+		die_if_kernel("Oops", regs);
+		force_sig(SIGBUS, current);
+	} else if (debug_be_interrupt)
+		show_regs((struct pt_regs *)regs);
+}
+
+static int ip28_be_handler(struct pt_regs *regs, int is_fixup)
+{
+	/*
+	 * We arrive here only in the unusual case of do_be() invocation,
+	 * i.e. by a bus error exception without a bus error interrupt.
+	 */
+	if (is_fixup) {
+		count_be_is_fixup++;
+		save_and_clear_buserr();
+		return MIPS_BE_FIXUP;
+	}
+	count_be_handler++;
+	return ip28_be_interrupt(regs);
+}
+
+void __init ip22_be_init(void)
+{
+	board_be_handler = ip28_be_handler;
+}
+
+int ip28_show_be_info(struct seq_file *m)
+{
+	seq_printf(m, "IP28 be fixups\t\t: %u\n", count_be_is_fixup);
+	seq_printf(m, "IP28 be interrupts\t: %u\n", count_be_interrupt);
+	seq_printf(m, "IP28 be handler\t\t: %u\n", count_be_handler);
+
+	return 0;
+}
+
+static int __init debug_be_setup(char *str)
+{
+	debug_be_interrupt++;
+	return 1;
+}
+__setup("ip28_debug_be", debug_be_setup);