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/system.h>
  19 #include <asm/r4kcache.h>
  20 #include <asm/hazards.h>
  21
  22 /*
  23  * These definitions are correct for the 24K/34K/74K SPRAM sample
  24  * implementation. The 4KS interpreted the tags differently...
  25  */
  26 #define SPRAM_TAG0_ENABLE       0x00000080
  27 #define SPRAM_TAG0_PA_MASK      0xfffff000
  28 #define SPRAM_TAG1_SIZE_MASK    0xfffff000
  29
  30 #define SPRAM_TAG_STRIDE        8
  31
  32 #define ERRCTL_SPRAM            (1 << 28)
  33
  34 /* errctl access */
  35 #define read_c0_errctl(x) read_c0_ecc(x)
  36 #define write_c0_errctl(x) write_c0_ecc(x)
  37
  38 /*
  39  * Different semantics to the set_c0_* function built by __BUILD_SET_C0
  40  */
  41 static __cpuinit unsigned int bis_c0_errctl(unsigned int set)
  42 {
  43         unsigned int res;
  44         res = read_c0_errctl();
  45         write_c0_errctl(res | set);
  46         return res;
  47 }
  48
  49 static __cpuinit void ispram_store_tag(unsigned int offset, unsigned int data)
  50 {
  51         unsigned int errctl;
  52
  53         /* enable SPRAM tag access */
  54         errctl = bis_c0_errctl(ERRCTL_SPRAM);
  55         ehb();
  56
  57         write_c0_taglo(data);
  58         ehb();
  59
  60         cache_op(Index_Store_Tag_I, CKSEG0|offset);
  61         ehb();
  62
  63         write_c0_errctl(errctl);
  64         ehb();
  65 }
  66
  67
  68 static __cpuinit unsigned int ispram_load_tag(unsigned int offset)
  69 {
  70         unsigned int data;
  71         unsigned int errctl;
  72
  73         /* enable SPRAM tag access */
  74         errctl = bis_c0_errctl(ERRCTL_SPRAM);
  75         ehb();
  76         cache_op(Index_Load_Tag_I, CKSEG0 | offset);
  77         ehb();
  78         data = read_c0_taglo();
  79         ehb();
  80         write_c0_errctl(errctl);
  81         ehb();
  82
  83         return data;
  84 }
  85
  86 static __cpuinit void dspram_store_tag(unsigned int offset, unsigned int data)
  87 {
  88         unsigned int errctl;
  89
  90         /* enable SPRAM tag access */
  91         errctl = bis_c0_errctl(ERRCTL_SPRAM);
  92         ehb();
  93         write_c0_dtaglo(data);
  94         ehb();
  95         cache_op(Index_Store_Tag_D, CKSEG0 | offset);
  96         ehb();
  97         write_c0_errctl(errctl);
  98         ehb();
  99 }
 100
 101
 102 static __cpuinit unsigned int dspram_load_tag(unsigned int offset)
 103 {
 104         unsigned int data;
 105         unsigned int errctl;
 106
 107         errctl = bis_c0_errctl(ERRCTL_SPRAM);
 108         ehb();
 109         cache_op(Index_Load_Tag_D, CKSEG0 | offset);
 110         ehb();
 111         data = read_c0_dtaglo();
 112         ehb();
 113         write_c0_errctl(errctl);
 114         ehb();
 115
 116         return data;
 117 }
 118
 119 static __cpuinit void probe_spram(char *type,
 120             unsigned int base,
 121             unsigned int (*read)(unsigned int),
 122             void (*write)(unsigned int, unsigned int))
 123 {
 124         unsigned int firstsize = 0, lastsize = 0;
 125         unsigned int firstpa = 0, lastpa = 0, pa = 0;
 126         unsigned int offset = 0;
 127         unsigned int size, tag0, tag1;
 128         unsigned int enabled;
 129         int i;
 130
 131         /*
 132          * The limit is arbitrary but avoids the loop running away if
 133          * the SPRAM tags are implemented differently
 134          */
 135
 136         for (i = 0; i < 8; i++) {
 137                 tag0 = read(offset);
 138                 tag1 = read(offset+SPRAM_TAG_STRIDE);
 139                 pr_debug("DBG %s%d: tag0=%08x tag1=%08x\n",
 140                          type, i, tag0, tag1);
 141
 142                 size = tag1 & SPRAM_TAG1_SIZE_MASK;
 143
 144                 if (size == 0)
 145                         break;
 146
 147                 if (i != 0) {
 148                         /* tags may repeat... */
 149                         if ((pa == firstpa && size == firstsize) ||
 150                             (pa == lastpa && size == lastsize))
 151                                 break;
 152                 }
 153
 154                 /* Align base with size */
 155                 base = (base + size - 1) & ~(size-1);
 156
 157                 /* reprogram the base address base address and enable */
 158                 tag0 = (base & SPRAM_TAG0_PA_MASK) | SPRAM_TAG0_ENABLE;
 159                 write(offset, tag0);
 160
 161                 base += size;
 162
 163                 /* reread the tag */
 164                 tag0 = read(offset);
 165                 pa = tag0 & SPRAM_TAG0_PA_MASK;
 166                 enabled = tag0 & SPRAM_TAG0_ENABLE;
 167
 168                 if (i == 0) {
 169                         firstpa = pa;
 170                         firstsize = size;
 171                 }
 172
 173                 lastpa = pa;
 174                 lastsize = size;
 175
 176                 if (strcmp(type, "DSPRAM") == 0) {
 177                         unsigned int *vp = (unsigned int *)(CKSEG1 | pa);
 178                         unsigned int v;
 179 #define TDAT    0x5a5aa5a5
 180                         vp[0] = TDAT;
 181                         vp[1] = ~TDAT;
 182
 183                         mb();
 184
 185                         v = vp[0];
 186                         if (v != TDAT)
 187                                 printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
 188                                        vp, TDAT, v);
 189                         v = vp[1];
 190                         if (v != ~TDAT)
 191                                 printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
 192                                        vp+1, ~TDAT, v);
 193                 }
 194
 195                 pr_info("%s%d: PA=%08x,Size=%08x%s\n",
 196                         type, i, pa, size, enabled ? ",enabled" : "");
 197                 offset += 2 * SPRAM_TAG_STRIDE;
 198         }
 199 }
 200 void __cpuinit spram_config(void)
 201 {
 202         struct cpuinfo_mips *c = &current_cpu_data;
 203         unsigned int config0;
 204
 205         switch (c->cputype) {
 206         case CPU_24K:
 207         case CPU_34K:
 208         case CPU_74K:
 209         case CPU_1004K:
 210                 config0 = read_c0_config();
 211                 /* FIXME: addresses are Malta specific */
 212                 if (config0 & (1<<24)) {
 213                         probe_spram("ISPRAM", 0x1c000000,
 214                                     &ispram_load_tag, &ispram_store_tag);
 215                 }
 216                 if (config0 & (1<<23))
 217                         probe_spram("DSPRAM", 0x1c100000,
 218                                     &dspram_load_tag, &dspram_store_tag);
 219         }
 220 }