arch/mips/kernel/spram.c

   1 /*
   2  * MIPS SPRAM support
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  *
   9  * Copyright (C) 2007, 2008 MIPS Technologies, Inc.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/stddef.h>
  15
  16 #include <asm/fpu.h>
  17 #include <asm/mipsregs.h>
  18 #include <asm/r4kcache.h>
  19 #include <asm/hazards.h>
  20
  21 /*
  22  * These definitions are correct for the 24K/34K/74K SPRAM sample
  23  * implementation. The 4KS interpreted the tags differently...
  24  */
  25 #define SPRAM_TAG0_ENABLE       0x00000080
  26 #define SPRAM_TAG0_PA_MASK      0xfffff000
  27 #define SPRAM_TAG1_SIZE_MASK    0xfffff000
  28
  29 #define SPRAM_TAG_STRIDE        8
  30
  31 #define ERRCTL_SPRAM            (1 << 28)
  32
  33 /* errctl access */
  34 #define read_c0_errctl(x) read_c0_ecc(x)
  35 #define write_c0_errctl(x) write_c0_ecc(x)
  36
  37 /*
  38  * Different semantics to the set_c0_* function built by __BUILD_SET_C0
  39  */
  40 static unsigned int bis_c0_errctl(unsigned int set)
  41 {
  42         unsigned int res;
  43         res = read_c0_errctl();
  44         write_c0_errctl(res | set);
  45         return res;
  46 }
  47
  48 static void ispram_store_tag(unsigned int offset, unsigned int data)
  49 {
  50         unsigned int errctl;
  51
  52         /* enable SPRAM tag access */
  53         errctl = bis_c0_errctl(ERRCTL_SPRAM);
  54         ehb();
  55
  56         write_c0_taglo(data);
  57         ehb();
  58
  59         cache_op(Index_Store_Tag_I, CKSEG0|offset);
  60         ehb();
  61
  62         write_c0_errctl(errctl);
  63         ehb();
  64 }
  65
  66
  67 static unsigned int ispram_load_tag(unsigned int offset)
  68 {
  69         unsigned int data;
  70         unsigned int errctl;
  71
  72         /* enable SPRAM tag access */
  73         errctl = bis_c0_errctl(ERRCTL_SPRAM);
  74         ehb();
  75         cache_op(Index_Load_Tag_I, CKSEG0 | offset);
  76         ehb();
  77         data = read_c0_taglo();
  78         ehb();
  79         write_c0_errctl(errctl);
  80         ehb();
  81
  82         return data;
  83 }
  84
  85 static void dspram_store_tag(unsigned int offset, unsigned int data)
  86 {
  87         unsigned int errctl;
  88
  89         /* enable SPRAM tag access */
  90         errctl = bis_c0_errctl(ERRCTL_SPRAM);
  91         ehb();
  92         write_c0_dtaglo(data);
  93         ehb();
  94         cache_op(Index_Store_Tag_D, CKSEG0 | offset);
  95         ehb();
  96         write_c0_errctl(errctl);
  97         ehb();
  98 }
  99
 100
 101 static unsigned int dspram_load_tag(unsigned int offset)
 102 {
 103         unsigned int data;
 104         unsigned int errctl;
 105
 106         errctl = bis_c0_errctl(ERRCTL_SPRAM);
 107         ehb();
 108         cache_op(Index_Load_Tag_D, CKSEG0 | offset);
 109         ehb();
 110         data = read_c0_dtaglo();
 111         ehb();
 112         write_c0_errctl(errctl);
 113         ehb();
 114
 115         return data;
 116 }
 117
 118 static void probe_spram(char *type,
 119             unsigned int base,
 120             unsigned int (*read)(unsigned int),
 121             void (*write)(unsigned int, unsigned int))
 122 {
 123         unsigned int firstsize = 0, lastsize = 0;
 124         unsigned int firstpa = 0, lastpa = 0, pa = 0;
 125         unsigned int offset = 0;
 126         unsigned int size, tag0, tag1;
 127         unsigned int enabled;
 128         int i;
 129
 130         /*
 131          * The limit is arbitrary but avoids the loop running away if
 132          * the SPRAM tags are implemented differently
 133          */
 134
 135         for (i = 0; i < 8; i++) {
 136                 tag0 = read(offset);
 137                 tag1 = read(offset+SPRAM_TAG_STRIDE);
 138                 pr_debug("DBG %s%d: tag0=%08x tag1=%08x\n",
 139                          type, i, tag0, tag1);
 140
 141                 size = tag1 & SPRAM_TAG1_SIZE_MASK;
 142
 143                 if (size == 0)
 144                         break;
 145
 146                 if (i != 0) {
 147                         /* tags may repeat... */
 148                         if ((pa == firstpa && size == firstsize) ||
 149                             (pa == lastpa && size == lastsize))
 150                                 break;
 151                 }
 152
 153                 /* Align base with size */
 154                 base = (base + size - 1) & ~(size-1);
 155
 156                 /* reprogram the base address base address and enable */
 157                 tag0 = (base & SPRAM_TAG0_PA_MASK) | SPRAM_TAG0_ENABLE;
 158                 write(offset, tag0);
 159
 160                 base += size;
 161
 162                 /* reread the tag */
 163                 tag0 = read(offset);
 164                 pa = tag0 & SPRAM_TAG0_PA_MASK;
 165                 enabled = tag0 & SPRAM_TAG0_ENABLE;
 166
 167                 if (i == 0) {
 168                         firstpa = pa;
 169                         firstsize = size;
 170                 }
 171
 172                 lastpa = pa;
 173                 lastsize = size;
 174
 175                 if (strcmp(type, "DSPRAM") == 0) {
 176                         unsigned int *vp = (unsigned int *)(CKSEG1 | pa);
 177                         unsigned int v;
 178 #define TDAT    0x5a5aa5a5
 179                         vp[0] = TDAT;
 180                         vp[1] = ~TDAT;
 181
 182                         mb();
 183
 184                         v = vp[0];
 185                         if (v != TDAT)
 186                                 printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
 187                                        vp, TDAT, v);
 188                         v = vp[1];
 189                         if (v != ~TDAT)
 190                                 printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
 191                                        vp+1, ~TDAT, v);
 192                 }
 193
 194                 pr_info("%s%d: PA=%08x,Size=%08x%s\n",
 195                         type, i, pa, size, enabled ? ",enabled" : "");
 196                 offset += 2 * SPRAM_TAG_STRIDE;
 197         }
 198 }
 199 void spram_config(void)
 200 {
 201         struct cpuinfo_mips *c = &current_cpu_data;
 202         unsigned int config0;
 203
 204         switch (c->cputype) {
 205         case CPU_24K:
 206         case CPU_34K:
 207         case CPU_74K:
 208         case CPU_1004K:
 209                 config0 = read_c0_config();
 210                 /* FIXME: addresses are Malta specific */
 211                 if (config0 & (1<<24)) {
 212                         probe_spram("ISPRAM", 0x1c000000,
 213                                     &ispram_load_tag, &ispram_store_tag);
 214                 }
 215                 if (config0 & (1<<23))
 216                         probe_spram("DSPRAM", 0x1c100000,
 217                                     &dspram_load_tag, &dspram_store_tag);
 218         }
 219 }