arch/metag/mm/l2cache.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/init.h>
   3 #include <linux/kernel.h>
   4 #include <linux/delay.h>
   5
   6 #include <asm/l2cache.h>
   7 #include <asm/metag_isa.h>
   8
   9 /* If non-0, then initialise the L2 cache */
  10 static int l2cache_init = 1;
  11 /* If non-0, then initialise the L2 cache prefetch */
  12 static int l2cache_init_pf = 1;
  13
  14 int l2c_pfenable;
  15
  16 static volatile u32 l2c_testdata[16] __initdata __aligned(64);
  17
  18 static int __init parse_l2cache(char *p)
  19 {
  20         char *cp = p;
  21
  22         if (get_option(&cp, &l2cache_init) != 1) {
  23                 pr_err("Bad l2cache parameter (%s)\n", p);
  24                 return 1;
  25         }
  26         return 0;
  27 }
  28 early_param("l2cache", parse_l2cache);
  29
  30 static int __init parse_l2cache_pf(char *p)
  31 {
  32         char *cp = p;
  33
  34         if (get_option(&cp, &l2cache_init_pf) != 1) {
  35                 pr_err("Bad l2cache_pf parameter (%s)\n", p);
  36                 return 1;
  37         }
  38         return 0;
  39 }
  40 early_param("l2cache_pf", parse_l2cache_pf);
  41
  42 static int __init meta_l2c_setup(void)
  43 {
  44         /*
  45          * If the L2 cache isn't even present, don't do anything, but say so in
  46          * the log.
  47          */
  48         if (!meta_l2c_is_present()) {
  49                 pr_info("L2 Cache: Not present\n");
  50                 return 0;
  51         }
  52
  53         /*
  54          * Check whether the line size is recognised.
  55          */
  56         if (!meta_l2c_linesize()) {
  57                 pr_warn_once("L2 Cache: unknown line size id (config=0x%08x)\n",
  58                              meta_l2c_config());
  59         }
  60
  61         /*
  62          * Initialise state.
  63          */
  64         l2c_pfenable = _meta_l2c_pf_is_enabled();
  65
  66         /*
  67          * Enable the L2 cache and print to log whether it was already enabled
  68          * by the bootloader.
  69          */
  70         if (l2cache_init) {
  71                 pr_info("L2 Cache: Enabling... ");
  72                 if (meta_l2c_enable())
  73                         pr_cont("already enabled\n");
  74                 else
  75                         pr_cont("done\n");
  76         } else {
  77                 pr_info("L2 Cache: Not enabling\n");
  78         }
  79
  80         /*
  81          * Enable L2 cache prefetch.
  82          */
  83         if (l2cache_init_pf) {
  84                 pr_info("L2 Cache: Enabling prefetch... ");
  85                 if (meta_l2c_pf_enable(1))
  86                         pr_cont("already enabled\n");
  87                 else
  88                         pr_cont("done\n");
  89         } else {
  90                 pr_info("L2 Cache: Not enabling prefetch\n");
  91         }
  92
  93         return 0;
  94 }
  95 core_initcall(meta_l2c_setup);
  96
  97 int meta_l2c_disable(void)
  98 {
  99         unsigned long flags;
 100         int en;
 101
 102         if (!meta_l2c_is_present())
 103                 return 1;
 104
 105         /*
 106          * Prevent other threads writing during the writeback, otherwise the
 107          * writes will get "lost" when the L2 is disabled.
 108          */
 109         __global_lock2(flags);
 110         en = meta_l2c_is_enabled();
 111         if (likely(en)) {
 112                 _meta_l2c_pf_enable(0);
 113                 wr_fence();
 114                 _meta_l2c_purge();
 115                 _meta_l2c_enable(0);
 116         }
 117         __global_unlock2(flags);
 118
 119         return !en;
 120 }
 121
 122 int meta_l2c_enable(void)
 123 {
 124         unsigned long flags;
 125         int en;
 126
 127         if (!meta_l2c_is_present())
 128                 return 0;
 129
 130         /*
 131          * Init (clearing the L2) can happen while the L2 is disabled, so other
 132          * threads are safe to continue executing, however we must not init the
 133          * cache if it's already enabled (dirty lines would be discarded), so
 134          * this operation should still be atomic with other threads.
 135          */
 136         __global_lock1(flags);
 137         en = meta_l2c_is_enabled();
 138         if (likely(!en)) {
 139                 _meta_l2c_init();
 140                 _meta_l2c_enable(1);
 141                 _meta_l2c_pf_enable(l2c_pfenable);
 142         }
 143         __global_unlock1(flags);
 144
 145         return en;
 146 }
 147
 148 int meta_l2c_pf_enable(int pfenable)
 149 {
 150         unsigned long flags;
 151         int en = l2c_pfenable;
 152
 153         if (!meta_l2c_is_present())
 154                 return 0;
 155
 156         /*
 157          * We read modify write the enable register, so this operation must be
 158          * atomic with other threads.
 159          */
 160         __global_lock1(flags);
 161         en = l2c_pfenable;
 162         l2c_pfenable = pfenable;
 163         if (meta_l2c_is_enabled())
 164                 _meta_l2c_pf_enable(pfenable);
 165         __global_unlock1(flags);
 166
 167         return en;
 168 }
 169
 170 int meta_l2c_flush(void)
 171 {
 172         unsigned long flags;
 173         int en;
 174
 175         /*
 176          * Prevent other threads writing during the writeback. This also
 177          * involves read modify writes.
 178          */
 179         __global_lock2(flags);
 180         en = meta_l2c_is_enabled();
 181         if (likely(en)) {
 182                 _meta_l2c_pf_enable(0);
 183                 wr_fence();
 184                 _meta_l2c_purge();
 185                 _meta_l2c_enable(0);
 186                 _meta_l2c_init();
 187                 _meta_l2c_enable(1);
 188                 _meta_l2c_pf_enable(l2c_pfenable);
 189         }
 190         __global_unlock2(flags);
 191
 192         return !en;
 193 }