arch/arm/mach-ep93xx/crunch.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm/kernel/crunch.c
   4  * Cirrus MaverickCrunch context switching and handling
   5  *
   6  * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/signal.h>
  13 #include <linux/sched.h>
  14 #include <linux/init.h>
  15 #include <linux/io.h>
  16
  17 #include <asm/thread_notify.h>
  18
  19 #include "soc.h"
  20
  21 struct crunch_state *crunch_owner;
  22
  23 void crunch_task_release(struct thread_info *thread)
  24 {
  25         local_irq_disable();
  26         if (crunch_owner == &thread->crunchstate)
  27                 crunch_owner = NULL;
  28         local_irq_enable();
  29 }
  30
  31 static int crunch_enabled(u32 devcfg)
  32 {
  33         return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
  34 }
  35
  36 static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
  37 {
  38         struct thread_info *thread = (struct thread_info *)t;
  39         struct crunch_state *crunch_state;
  40         u32 devcfg;
  41
  42         crunch_state = &thread->crunchstate;
  43
  44         switch (cmd) {
  45         case THREAD_NOTIFY_FLUSH:
  46                 memset(crunch_state, 0, sizeof(*crunch_state));
  47
  48                 /*
  49                  * FALLTHROUGH: Ensure we don't try to overwrite our newly
  50                  * initialised state information on the first fault.
  51                  */
  52                 fallthrough;
  53
  54         case THREAD_NOTIFY_EXIT:
  55                 crunch_task_release(thread);
  56                 break;
  57
  58         case THREAD_NOTIFY_SWITCH:
  59                 devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
  60                 if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
  61                         /*
  62                          * We don't use ep93xx_syscon_swlocked_write() here
  63                          * because we are on the context switch path and
  64                          * preemption is already disabled.
  65                          */
  66                         devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
  67                         __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
  68                         __raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
  69                 }
  70                 break;
  71         }
  72
  73         return NOTIFY_DONE;
  74 }
  75
  76 static struct notifier_block crunch_notifier_block = {
  77         .notifier_call  = crunch_do,
  78 };
  79
  80 int __init crunch_init(void)
  81 {
  82         thread_register_notifier(&crunch_notifier_block);
  83         elf_hwcap |= HWCAP_CRUNCH;
  84
  85         return 0;
  86 }