arch/mips/dec/ecc-berr.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Bus error event handling code for systems equipped with ECC
   4  *      handling logic, i.e. DECstation/DECsystem 5000/200 (KN02),
   5  *      5000/240 (KN03), 5000/260 (KN05) and DECsystem 5900 (KN03),
   6  *      5900/260 (KN05) systems.
   7  *
   8  *      Copyright (c) 2003, 2005  Maciej W. Rozycki
   9  */
  10
  11 #include <linux/init.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/types.h>
  16
  17 #include <asm/addrspace.h>
  18 #include <asm/bootinfo.h>
  19 #include <asm/cpu.h>
  20 #include <asm/cpu-type.h>
  21 #include <asm/irq_regs.h>
  22 #include <asm/processor.h>
  23 #include <asm/ptrace.h>
  24 #include <asm/traps.h>
  25
  26 #include <asm/dec/ecc.h>
  27 #include <asm/dec/kn02.h>
  28 #include <asm/dec/kn03.h>
  29 #include <asm/dec/kn05.h>
  30
  31 static volatile u32 *kn0x_erraddr;
  32 static volatile u32 *kn0x_chksyn;
  33
  34 static inline void dec_ecc_be_ack(void)
  35 {
  36         *kn0x_erraddr = 0;                      /* any write clears the IRQ */
  37         iob();
  38 }
  39
  40 static int dec_ecc_be_backend(struct pt_regs *regs, int is_fixup, int invoker)
  41 {
  42         static const char excstr[] = "exception";
  43         static const char intstr[] = "interrupt";
  44         static const char cpustr[] = "CPU";
  45         static const char dmastr[] = "DMA";
  46         static const char readstr[] = "read";
  47         static const char mreadstr[] = "memory read";
  48         static const char writestr[] = "write";
  49         static const char mwritstr[] = "partial memory write";
  50         static const char timestr[] = "timeout";
  51         static const char overstr[] = "overrun";
  52         static const char eccstr[] = "ECC error";
  53
  54         const char *kind, *agent, *cycle, *event;
  55         const char *status = "", *xbit = "", *fmt = "";
  56         unsigned long address;
  57         u16 syn = 0, sngl;
  58
  59         int i = 0;
  60
  61         u32 erraddr = *kn0x_erraddr;
  62         u32 chksyn = *kn0x_chksyn;
  63         int action = MIPS_BE_FATAL;
  64
  65         /* For non-ECC ack ASAP, so that any subsequent errors get caught. */
  66         if ((erraddr & (KN0X_EAR_VALID | KN0X_EAR_ECCERR)) == KN0X_EAR_VALID)
  67                 dec_ecc_be_ack();
  68
  69         kind = invoker ? intstr : excstr;
  70
  71         if (!(erraddr & KN0X_EAR_VALID)) {
  72                 /* No idea what happened. */
  73                 printk(KERN_ALERT "Unidentified bus error %s\n", kind);
  74                 return action;
  75         }
  76
  77         agent = (erraddr & KN0X_EAR_CPU) ? cpustr : dmastr;
  78
  79         if (erraddr & KN0X_EAR_ECCERR) {
  80                 /* An ECC error on a CPU or DMA transaction. */
  81                 cycle = (erraddr & KN0X_EAR_WRITE) ? mwritstr : mreadstr;
  82                 event = eccstr;
  83         } else {
  84                 /* A CPU timeout or a DMA overrun. */
  85                 cycle = (erraddr & KN0X_EAR_WRITE) ? writestr : readstr;
  86                 event = (erraddr & KN0X_EAR_CPU) ? timestr : overstr;
  87         }
  88
  89         address = erraddr & KN0X_EAR_ADDRESS;
  90         /* For ECC errors on reads adjust for MT pipelining. */
  91         if ((erraddr & (KN0X_EAR_WRITE | KN0X_EAR_ECCERR)) == KN0X_EAR_ECCERR)
  92                 address = (address & ~0xfffLL) | ((address - 5) & 0xfffLL);
  93         address <<= 2;
  94
  95         /* Only CPU errors are fixable. */
  96         if (erraddr & KN0X_EAR_CPU && is_fixup)
  97                 action = MIPS_BE_FIXUP;
  98
  99         if (erraddr & KN0X_EAR_ECCERR) {
 100                 static const u8 data_sbit[32] = {
 101                         0x4f, 0x4a, 0x52, 0x54, 0x57, 0x58, 0x5b, 0x5d,
 102                         0x23, 0x25, 0x26, 0x29, 0x2a, 0x2c, 0x31, 0x34,
 103                         0x0e, 0x0b, 0x13, 0x15, 0x16, 0x19, 0x1a, 0x1c,
 104                         0x62, 0x64, 0x67, 0x68, 0x6b, 0x6d, 0x70, 0x75,
 105                 };
 106                 static const u8 data_mbit[25] = {
 107                         0x07, 0x0d, 0x1f,
 108                         0x2f, 0x32, 0x37, 0x38, 0x3b, 0x3d, 0x3e,
 109                         0x43, 0x45, 0x46, 0x49, 0x4c, 0x51, 0x5e,
 110                         0x61, 0x6e, 0x73, 0x76, 0x79, 0x7a, 0x7c, 0x7f,
 111                 };
 112                 static const char sbestr[] = "corrected single";
 113                 static const char dbestr[] = "uncorrectable double";
 114                 static const char mbestr[] = "uncorrectable multiple";
 115
 116                 if (!(address & 0x4))
 117                         syn = chksyn;                   /* Low bank. */
 118                 else
 119                         syn = chksyn >> 16;             /* High bank. */
 120
 121                 if (!(syn & KN0X_ESR_VLDLO)) {
 122                         /* Ack now, no rewrite will happen. */
 123                         dec_ecc_be_ack();
 124
 125                         fmt = KERN_ALERT "%s" "invalid\n";
 126                 } else {
 127                         sngl = syn & KN0X_ESR_SNGLO;
 128                         syn &= KN0X_ESR_SYNLO;
 129
 130                         /*
 131                          * Multibit errors may be tagged incorrectly;
 132                          * check the syndrome explicitly.
 133                          */
 134                         for (i = 0; i < 25; i++)
 135                                 if (syn == data_mbit[i])
 136                                         break;
 137
 138                         if (i < 25) {
 139                                 status = mbestr;
 140                         } else if (!sngl) {
 141                                 status = dbestr;
 142                         } else {
 143                                 volatile u32 *ptr =
 144                                         (void *)CKSEG1ADDR(address);
 145
 146                                 *ptr = *ptr;            /* Rewrite. */
 147                                 iob();
 148
 149                                 status = sbestr;
 150                                 action = MIPS_BE_DISCARD;
 151                         }
 152
 153                         /* Ack now, now we've rewritten (or not). */
 154                         dec_ecc_be_ack();
 155
 156                         if (syn && syn == (syn & -syn)) {
 157                                 if (syn == 0x01) {
 158                                         fmt = KERN_ALERT "%s"
 159                                               "%#04x -- %s bit error "
 160                                               "at check bit C%s\n";
 161                                         xbit = "X";
 162                                 } else {
 163                                         fmt = KERN_ALERT "%s"
 164                                               "%#04x -- %s bit error "
 165                                               "at check bit C%s%u\n";
 166                                 }
 167                                 i = syn >> 2;
 168                         } else {
 169                                 for (i = 0; i < 32; i++)
 170                                         if (syn == data_sbit[i])
 171                                                 break;
 172                                 if (i < 32)
 173                                         fmt = KERN_ALERT "%s"
 174                                               "%#04x -- %s bit error "
 175                                               "at data bit D%s%u\n";
 176                                 else
 177                                         fmt = KERN_ALERT "%s"
 178                                               "%#04x -- %s bit error\n";
 179                         }
 180                 }
 181         }
 182
 183         if (action != MIPS_BE_FIXUP)
 184                 printk(KERN_ALERT "Bus error %s: %s %s %s at %#010lx\n",
 185                         kind, agent, cycle, event, address);
 186
 187         if (action != MIPS_BE_FIXUP && erraddr & KN0X_EAR_ECCERR)
 188                 printk(fmt, "  ECC syndrome ", syn, status, xbit, i);
 189
 190         return action;
 191 }
 192
 193 int dec_ecc_be_handler(struct pt_regs *regs, int is_fixup)
 194 {
 195         return dec_ecc_be_backend(regs, is_fixup, 0);
 196 }
 197
 198 irqreturn_t dec_ecc_be_interrupt(int irq, void *dev_id)
 199 {
 200         struct pt_regs *regs = get_irq_regs();
 201
 202         int action = dec_ecc_be_backend(regs, 0, 1);
 203
 204         if (action == MIPS_BE_DISCARD)
 205                 return IRQ_HANDLED;
 206
 207         /*
 208          * FIXME: Find the affected processes and kill them, otherwise
 209          * we must die.
 210          *
 211          * The interrupt is asynchronously delivered thus EPC and RA
 212          * may be irrelevant, but are printed for a reference.
 213          */
 214         printk(KERN_ALERT "Fatal bus interrupt, epc == %08lx, ra == %08lx\n",
 215                regs->cp0_epc, regs->regs[31]);
 216         die("Unrecoverable bus error", regs);
 217 }
 218
 219
 220 /*
 221  * Initialization differs a bit between KN02 and KN03/KN05, so we
 222  * need two variants.  Once set up, all systems can be handled the
 223  * same way.
 224  */
 225 static inline void dec_kn02_be_init(void)
 226 {
 227         volatile u32 *csr = (void *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_CSR);
 228
 229         kn0x_erraddr = (void *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_ERRADDR);
 230         kn0x_chksyn = (void *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_CHKSYN);
 231
 232         /* Preset write-only bits of the Control Register cache. */
 233         cached_kn02_csr = *csr | KN02_CSR_LEDS;
 234
 235         /* Set normal ECC detection and generation. */
 236         cached_kn02_csr &= ~(KN02_CSR_DIAGCHK | KN02_CSR_DIAGGEN);
 237         /* Enable ECC correction. */
 238         cached_kn02_csr |= KN02_CSR_CORRECT;
 239         *csr = cached_kn02_csr;
 240         iob();
 241 }
 242
 243 static inline void dec_kn03_be_init(void)
 244 {
 245         volatile u32 *mcr = (void *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_MCR);
 246         volatile u32 *mbcs = (void *)CKSEG1ADDR(KN4K_SLOT_BASE + KN4K_MB_CSR);
 247
 248         kn0x_erraddr = (void *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_ERRADDR);
 249         kn0x_chksyn = (void *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_CHKSYN);
 250
 251         /*
 252          * Set normal ECC detection and generation, enable ECC correction.
 253          * For KN05 we also need to make sure EE (?) is enabled in the MB.
 254          * Otherwise DBE/IBE exceptions would be masked but bus error
 255          * interrupts would still arrive, resulting in an inevitable crash
 256          * if get_dbe() triggers one.
 257          */
 258         *mcr = (*mcr & ~(KN03_MCR_DIAGCHK | KN03_MCR_DIAGGEN)) |
 259                KN03_MCR_CORRECT;
 260         if (current_cpu_type() == CPU_R4400SC)
 261                 *mbcs |= KN4K_MB_CSR_EE;
 262         fast_iob();
 263 }
 264
 265 void __init dec_ecc_be_init(void)
 266 {
 267         if (mips_machtype == MACH_DS5000_200)
 268                 dec_kn02_be_init();
 269         else
 270                 dec_kn03_be_init();
 271
 272         /* Clear any leftover errors from the firmware. */
 273         dec_ecc_be_ack();
 274 }