kernel/arch/metag/mm/l2cache.c

   1 #include <linux/init.h>
   2 #include <linux/kernel.h>
   3 #include <linux/delay.h>
   4
   5 #include <asm/l2cache.h>
   6 #include <asm/metag_isa.h>
   7
   8 /* If non-0, then initialise the L2 cache */
   9 static int l2cache_init = 1;
  10 /* If non-0, then initialise the L2 cache prefetch */
  11 static int l2cache_init_pf = 1;
  12
  13 int l2c_pfenable;
  14
  15 static volatile u32 l2c_testdata[16] __initdata __aligned(64);
  16
  17 static int __init parse_l2cache(char *p)
  18 {
  19         char *cp = p;
  20
  21         if (get_option(&cp, &l2cache_init) != 1) {
  22                 pr_err("Bad l2cache parameter (%s)\n", p);
  23                 return 1;
  24         }
  25         return 0;
  26 }
  27 early_param("l2cache", parse_l2cache);
  28
  29 static int __init parse_l2cache_pf(char *p)
  30 {
  31         char *cp = p;
  32
  33         if (get_option(&cp, &l2cache_init_pf) != 1) {
  34                 pr_err("Bad l2cache_pf parameter (%s)\n", p);
  35                 return 1;
  36         }
  37         return 0;
  38 }
  39 early_param("l2cache_pf", parse_l2cache_pf);
  40
  41 static int __init meta_l2c_setup(void)
  42 {
  43         /*
  44          * If the L2 cache isn't even present, don't do anything, but say so in
  45          * the log.
  46          */
  47         if (!meta_l2c_is_present()) {
  48                 pr_info("L2 Cache: Not present\n");
  49                 return 0;
  50         }
  51
  52         /*
  53          * Check whether the line size is recognised.
  54          */
  55         if (!meta_l2c_linesize()) {
  56                 pr_warn_once("L2 Cache: unknown line size id (config=0x%08x)\n",
  57                              meta_l2c_config());
  58         }
  59
  60         /*
  61          * Initialise state.
  62          */
  63         l2c_pfenable = _meta_l2c_pf_is_enabled();
  64
  65         /*
  66          * Enable the L2 cache and print to log whether it was already enabled
  67          * by the bootloader.
  68          */
  69         if (l2cache_init) {
  70                 pr_info("L2 Cache: Enabling... ");
  71                 if (meta_l2c_enable())
  72                         pr_cont("already enabled\n");
  73                 else
  74                         pr_cont("done\n");
  75         } else {
  76                 pr_info("L2 Cache: Not enabling\n");
  77         }
  78
  79         /*
  80          * Enable L2 cache prefetch.
  81          */
  82         if (l2cache_init_pf) {
  83                 pr_info("L2 Cache: Enabling prefetch... ");
  84                 if (meta_l2c_pf_enable(1))
  85                         pr_cont("already enabled\n");
  86                 else
  87                         pr_cont("done\n");
  88         } else {
  89                 pr_info("L2 Cache: Not enabling prefetch\n");
  90         }
  91
  92         return 0;
  93 }
  94 core_initcall(meta_l2c_setup);
  95
  96 int meta_l2c_disable(void)
  97 {
  98         unsigned long flags;
  99         int en;
 100
 101         if (!meta_l2c_is_present())
 102                 return 1;
 103
 104         /*
 105          * Prevent other threads writing during the writeback, otherwise the
 106          * writes will get "lost" when the L2 is disabled.
 107          */
 108         __global_lock2(flags);
 109         en = meta_l2c_is_enabled();
 110         if (likely(en)) {
 111                 _meta_l2c_pf_enable(0);
 112                 wr_fence();
 113                 _meta_l2c_purge();
 114                 _meta_l2c_enable(0);
 115         }
 116         __global_unlock2(flags);
 117
 118         return !en;
 119 }
 120
 121 int meta_l2c_enable(void)
 122 {
 123         unsigned long flags;
 124         int en;
 125
 126         if (!meta_l2c_is_present())
 127                 return 0;
 128
 129         /*
 130          * Init (clearing the L2) can happen while the L2 is disabled, so other
 131          * threads are safe to continue executing, however we must not init the
 132          * cache if it's already enabled (dirty lines would be discarded), so
 133          * this operation should still be atomic with other threads.
 134          */
 135         __global_lock1(flags);
 136         en = meta_l2c_is_enabled();
 137         if (likely(!en)) {
 138                 _meta_l2c_init();
 139                 _meta_l2c_enable(1);
 140                 _meta_l2c_pf_enable(l2c_pfenable);
 141         }
 142         __global_unlock1(flags);
 143
 144         return en;
 145 }
 146
 147 int meta_l2c_pf_enable(int pfenable)
 148 {
 149         unsigned long flags;
 150         int en = l2c_pfenable;
 151
 152         if (!meta_l2c_is_present())
 153                 return 0;
 154
 155         /*
 156          * We read modify write the enable register, so this operation must be
 157          * atomic with other threads.
 158          */
 159         __global_lock1(flags);
 160         en = l2c_pfenable;
 161         l2c_pfenable = pfenable;
 162         if (meta_l2c_is_enabled())
 163                 _meta_l2c_pf_enable(pfenable);
 164         __global_unlock1(flags);
 165
 166         return en;
 167 }
 168
 169 int meta_l2c_flush(void)
 170 {
 171         unsigned long flags;
 172         int en;
 173
 174         /*
 175          * Prevent other threads writing during the writeback. This also
 176          * involves read modify writes.
 177          */
 178         __global_lock2(flags);
 179         en = meta_l2c_is_enabled();
 180         if (likely(en)) {
 181                 _meta_l2c_pf_enable(0);
 182                 wr_fence();
 183                 _meta_l2c_purge();
 184                 _meta_l2c_enable(0);
 185                 _meta_l2c_init();
 186                 _meta_l2c_enable(1);
 187                 _meta_l2c_pf_enable(l2c_pfenable);
 188         }
 189         __global_unlock2(flags);
 190
 191         return !en;
 192 }