// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Bus error event handling code for systems equipped with ECC
* handling logic, i.e. DECstation/DECsystem 5000/200 (KN02),
* 5000/240 (KN03), 5000/260 (KN05) and DECsystem 5900 (KN03),
* 5900/260 (KN05) systems.
*
* Copyright (c) 2003, 2005 Maciej W. Rozycki
*/
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <asm/addrspace.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/cpu-type.h>
#include <asm/irq_regs.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/traps.h>
#include <asm/dec/ecc.h>
#include <asm/dec/kn02.h>
#include <asm/dec/kn03.h>
#include <asm/dec/kn05.h>
static volatile u32 *kn0x_erraddr;
static volatile u32 *kn0x_chksyn;
static inline void dec_ecc_be_ack(void)
{
*kn0x_erraddr = 0; /* any write clears the IRQ */
iob();
}
static int dec_ecc_be_backend(struct pt_regs *regs, int is_fixup, int invoker)
{
static const char excstr[] = "exception";
static const char intstr[] = "interrupt";
static const char cpustr[] = "CPU";
static const char dmastr[] = "DMA";
static const char readstr[] = "read";
static const char mreadstr[] = "memory read";
static const char writestr[] = "write";
static const char mwritstr[] = "partial memory write";
static const char timestr[] = "timeout";
static const char overstr[] = "overrun";
static const char eccstr[] = "ECC error";
const char *kind, *agent, *cycle, *event;
const char *status = "", *xbit = "", *fmt = "";
unsigned long address;
u16 syn = 0, sngl;
int i = 0;
u32 erraddr = *kn0x_erraddr;
u32 chksyn = *kn0x_chksyn;
int action = MIPS_BE_FATAL;
/* For non-ECC ack ASAP, so that any subsequent errors get caught. */
if ((erraddr & (KN0X_EAR_VALID | KN0X_EAR_ECCERR)) == KN0X_EAR_VALID)
dec_ecc_be_ack();
kind = invoker ? intstr : excstr;
if (!(erraddr & KN0X_EAR_VALID)) {
/* No idea what happened. */
printk(KERN_ALERT "Unidentified bus error %s\n", kind);
return action;
}
agent = (erraddr & KN0X_EAR_CPU) ? cpustr : dmastr;
if (erraddr & KN0X_EAR_ECCERR) {
/* An ECC error on a CPU or DMA transaction. */
cycle = (erraddr & KN0X_EAR_WRITE) ? mwritstr : mreadstr;
event = eccstr;
} else {
/* A CPU timeout or a DMA overrun. */
cycle = (erraddr & KN0X_EAR_WRITE) ? writestr : readstr;
event = (erraddr & KN0X_EAR_CPU) ? timestr : overstr;
}
address = erraddr & KN0X_EAR_ADDRESS;
/* For ECC errors on reads adjust for MT pipelining. */
if ((erraddr & (KN0X_EAR_WRITE | KN0X_EAR_ECCERR)) == KN0X_EAR_ECCERR)
address = (address & ~0xfffLL) | ((address - 5) & 0xfffLL);
address <<= 2;
/* Only CPU errors are fixable. */
if (erraddr & KN0X_EAR_CPU && is_fixup)
action = MIPS_BE_FIXUP;
if (erraddr & KN0X_EAR_ECCERR) {
static const u8 data_sbit[32] = {
0x4f, 0x4a, 0x52, 0x54, 0x57, 0x58, 0x5b, 0x5d,
0x23, 0x25, 0x26, 0x29, 0x2a, 0x2c, 0x31, 0x34,
0x0e, 0x0b, 0x13, 0x15, 0x16, 0x19, 0x1a, 0x1c,
0x62, 0x64, 0x67, 0x68, 0x6b, 0x6d, 0x70, 0x75,
};
static const u8 data_mbit[25] = {
0x07, 0x0d, 0x1f,
0x2f, 0x32, 0x37, 0x38, 0x3b, 0x3d, 0x3e,
0x43, 0x45, 0x46, 0x49, 0x4c, 0x51, 0x5e,
0x61, 0x6e, 0x73, 0x76, 0x79, 0x7a, 0x7c, 0x7f,
};
static const char sbestr[] = "corrected single";
static const char dbestr[] = "uncorrectable double";
static const char mbestr[] = "uncorrectable multiple";
if (!(address & 0x4))
syn = chksyn; /* Low bank. */
else
syn = chksyn >> 16; /* High bank. */
if (!(syn & KN0X_ESR_VLDLO)) {
/* Ack now, no rewrite will happen. */
dec_ecc_be_ack();
fmt = KERN_ALERT "%s" "invalid\n";
} else {
sngl = syn & KN0X_ESR_SNGLO;
syn &= KN0X_ESR_SYNLO;
/*
* Multibit errors may be tagged incorrectly;
* check the syndrome explicitly.
*/
for (i = 0; i < 25; i++)
if (syn == data_mbit[i])
break;
if (i < 25) {
status = mbestr;
} else if (!sngl) {
status = dbestr;
} else {
volatile u32 *ptr =
(void *)CKSEG1ADDR(address);
*ptr = *ptr; /* Rewrite. */
iob();
status = sbestr;
action = MIPS_BE_DISCARD;
}
/* Ack now, now we've rewritten (or not). */
dec_ecc_be_ack();
if (syn && syn == (syn & -syn)) {
if (syn == 0x01) {
fmt = KERN_ALERT "%s"
"%#04x -- %s bit error "
"at check bit C%s\n";
xbit = "X";
} else {
fmt = KERN_ALERT "%s"
"%#04x -- %s bit error "
"at check bit C%s%u\n";
}
i = syn >> 2;
} else {
for (i = 0; i < 32; i++)
if (syn == data_sbit[i])
break;
if (i < 32)
fmt = KERN_ALERT "%s"
"%#04x -- %s bit error "
"at data bit D%s%u\n";
else
fmt = KERN_ALERT "%s"
"%#04x -- %s bit error\n";
}
}
}
if (action != MIPS_BE_FIXUP)
printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n",
kind, agent, cycle, event, address);
if (action != MIPS_BE_FIXUP && erraddr & KN0X_EAR_ECCERR)
printk(fmt, " ECC syndrome ", syn, status, xbit, i);
return action;
}
int dec_ecc_be_handler(struct pt_regs *regs, int is_fixup)
{
return dec_ecc_be_backend(regs, is_fixup, 0);
}
irqreturn_t dec_ecc_be_interrupt(int irq, void *dev_id)
{
struct pt_regs *regs = get_irq_regs();
int action = dec_ecc_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);
}
/*
* Initialization differs a bit between KN02 and KN03/KN05, so we
* need two variants. Once set up, all systems can be handled the
* same way.
*/
static inline void dec_kn02_be_init(void)
{
volatile u32 *csr = (void *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_CSR);
kn0x_erraddr = (void *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_ERRADDR);
kn0x_chksyn = (void *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_CHKSYN);
/* Preset write-only bits of the Control Register cache. */
cached_kn02_csr = *csr | KN02_CSR_LEDS;
/* Set normal ECC detection and generation. */
cached_kn02_csr &= ~(KN02_CSR_DIAGCHK | KN02_CSR_DIAGGEN);
/* Enable ECC correction. */
cached_kn02_csr |= KN02_CSR_CORRECT;
*csr = cached_kn02_csr;
iob();
}
static inline void dec_kn03_be_init(void)
{
volatile u32 *mcr = (void *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_MCR);
volatile u32 *mbcs = (void *)CKSEG1ADDR(KN4K_SLOT_BASE + KN4K_MB_CSR);
kn0x_erraddr = (void *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_ERRADDR);
kn0x_chksyn = (void *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_CHKSYN);
/*
* Set normal ECC detection and generation, enable ECC correction.
* For KN05 we also need to make sure EE (?) is enabled in the MB.
* Otherwise DBE/IBE exceptions would be masked but bus error
* interrupts would still arrive, resulting in an inevitable crash
* if get_dbe() triggers one.
*/
*mcr = (*mcr & ~(KN03_MCR_DIAGCHK | KN03_MCR_DIAGGEN)) |
KN03_MCR_CORRECT;
if (current_cpu_type() == CPU_R4400SC)
*mbcs |= KN4K_MB_CSR_EE;
fast_iob();
}
void __init dec_ecc_be_init(void)
{
if (mips_machtype == MACH_DS5000_200)
dec_kn02_be_init();
else
dec_kn03_be_init();
/* Clear any leftover errors from the firmware. */
dec_ecc_be_ack();
}