arch/mips/mm/sc-mips.c

   1 /*
   2  * Copyright (C) 2006 Chris Dearman (chris@mips.com),
   3  */
   4 #include <linux/init.h>
   5 #include <linux/kernel.h>
   6 #include <linux/sched.h>
   7 #include <linux/mm.h>
   8
   9 #include <asm/mipsregs.h>
  10 #include <asm/bcache.h>
  11 #include <asm/cacheops.h>
  12 #include <asm/page.h>
  13 #include <asm/pgtable.h>
  14 #include <asm/mmu_context.h>
  15 #include <asm/r4kcache.h>
  16
  17 /*
  18  * MIPS32/MIPS64 L2 cache handling
  19  */
  20
  21 /*
  22  * Writeback and invalidate the secondary cache before DMA.
  23  */
  24 static void mips_sc_wback_inv(unsigned long addr, unsigned long size)
  25 {
  26         blast_scache_range(addr, addr + size);
  27 }
  28
  29 /*
  30  * Invalidate the secondary cache before DMA.
  31  */
  32 static void mips_sc_inv(unsigned long addr, unsigned long size)
  33 {
  34         unsigned long lsize = cpu_scache_line_size();
  35         unsigned long almask = ~(lsize - 1);
  36
  37         cache_op(Hit_Writeback_Inv_SD, addr & almask);
  38         cache_op(Hit_Writeback_Inv_SD, (addr + size - 1) & almask);
  39         blast_inv_scache_range(addr, addr + size);
  40 }
  41
  42 static void mips_sc_enable(void)
  43 {
  44         /* L2 cache is permanently enabled */
  45 }
  46
  47 static void mips_sc_disable(void)
  48 {
  49         /* L2 cache is permanently enabled */
  50 }
  51
  52 static struct bcache_ops mips_sc_ops = {
  53         .bc_enable = mips_sc_enable,
  54         .bc_disable = mips_sc_disable,
  55         .bc_wback_inv = mips_sc_wback_inv,
  56         .bc_inv = mips_sc_inv
  57 };
  58
  59 /*
  60  * Check if the L2 cache controller is activated on a particular platform.
  61  * MTI's L2 controller and the L2 cache controller of Broadcom's BMIPS
  62  * cores both use c0_config2's bit 12 as "L2 Bypass" bit, that is the
  63  * cache being disabled.  However there is no guarantee for this to be
  64  * true on all platforms.  In an act of stupidity the spec defined bits
  65  * 12..15 as implementation defined so below function will eventually have
  66  * to be replaced by a platform specific probe.
  67  */
  68 static inline int mips_sc_is_activated(struct cpuinfo_mips *c)
  69 {
  70         unsigned int config2 = read_c0_config2();
  71         unsigned int tmp;
  72
  73         /* Check the bypass bit (L2B) */
  74         switch (c->cputype) {
  75         case CPU_34K:
  76         case CPU_74K:
  77         case CPU_1004K:
  78         case CPU_BMIPS5000:
  79                 if (config2 & (1 << 12))
  80                         return 0;
  81         }
  82
  83         tmp = (config2 >> 4) & 0x0f;
  84         if (0 < tmp && tmp <= 7)
  85                 c->scache.linesz = 2 << tmp;
  86         else
  87                 return 0;
  88         return 1;
  89 }
  90
  91 static inline int __init mips_sc_probe(void)
  92 {
  93         struct cpuinfo_mips *c = &current_cpu_data;
  94         unsigned int config1, config2;
  95         unsigned int tmp;
  96
  97         /* Mark as not present until probe completed */
  98         c->scache.flags |= MIPS_CACHE_NOT_PRESENT;
  99
 100         /* Ignore anything but MIPSxx processors */
 101         if (!(c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M32R2 |
 102                               MIPS_CPU_ISA_M64R1 | MIPS_CPU_ISA_M64R2)))
 103                 return 0;
 104
 105         /* Does this MIPS32/MIPS64 CPU have a config2 register? */
 106         config1 = read_c0_config1();
 107         if (!(config1 & MIPS_CONF_M))
 108                 return 0;
 109
 110         config2 = read_c0_config2();
 111
 112         if (!mips_sc_is_activated(c))
 113                 return 0;
 114
 115         tmp = (config2 >> 8) & 0x0f;
 116         if (0 <= tmp && tmp <= 7)
 117                 c->scache.sets = 64 << tmp;
 118         else
 119                 return 0;
 120
 121         tmp = (config2 >> 0) & 0x0f;
 122         if (0 <= tmp && tmp <= 7)
 123                 c->scache.ways = tmp + 1;
 124         else
 125                 return 0;
 126
 127         c->scache.waysize = c->scache.sets * c->scache.linesz;
 128         c->scache.waybit = __ffs(c->scache.waysize);
 129
 130         c->scache.flags &= ~MIPS_CACHE_NOT_PRESENT;
 131
 132         return 1;
 133 }
 134
 135 int mips_sc_init(void)
 136 {
 137         int found = mips_sc_probe();
 138         if (found) {
 139                 mips_sc_enable();
 140                 bcops = &mips_sc_ops;
 141         }
 142         return found;
 143 }