arch/blackfin/kernel/reboot.c

   1 /*
   2  * arch/blackfin/kernel/reboot.c - handle shutdown/reboot
   3  *
   4  * Copyright 2004-2007 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <asm/bfin-global.h>
  11 #include <asm/reboot.h>
  12 #include <asm/system.h>
  13 #include <asm/bfrom.h>
  14
  15 /* A system soft reset makes external memory unusable so force
  16  * this function into L1.  We use the compiler ssync here rather
  17  * than SSYNC() because it's safe (no interrupts and such) and
  18  * we save some L1.  We do not need to force sanity in the SYSCR
  19  * register as the BMODE selection bit is cleared by the soft
  20  * reset while the Core B bit (on dual core parts) is cleared by
  21  * the core reset.
  22  */
  23 __attribute__ ((__l1_text__, __noreturn__))
  24 static void bfin_reset(void)
  25 {
  26         if (!ANOMALY_05000353 && !ANOMALY_05000386)
  27                 bfrom_SoftReset((void *)(L1_SCRATCH_START + L1_SCRATCH_LENGTH - 20));
  28
  29         /* Wait for completion of "system" events such as cache line
  30          * line fills so that we avoid infinite stalls later on as
  31          * much as possible.  This code is in L1, so it won't trigger
  32          * any such event after this point in time.
  33          */
  34         __builtin_bfin_ssync();
  35
  36         /* Initiate System software reset. */
  37         bfin_write_SWRST(0x7);
  38
  39         /* Due to the way reset is handled in the hardware, we need
  40          * to delay for 10 SCLKS.  The only reliable way to do this is
  41          * to calculate the CCLK/SCLK ratio and multiply 10.  For now,
  42          * we'll assume worse case which is a 1:15 ratio.
  43          */
  44         asm(
  45                 "LSETUP (1f, 1f) LC0 = %0\n"
  46                 "1: nop;"
  47                 :
  48                 : "a" (15 * 10)
  49                 : "LC0", "LB0", "LT0"
  50         );
  51
  52         /* Clear System software reset */
  53         bfin_write_SWRST(0);
  54
  55         /* The BF526 ROM will crash during reset */
  56 #if defined(__ADSPBF522__) || defined(__ADSPBF524__) || defined(__ADSPBF526__)
  57         /* Seems to be fixed with newer parts though ... */
  58         if (__SILICON_REVISION__ < 1 && bfin_revid() < 1)
  59                 bfin_read_SWRST();
  60 #endif
  61
  62         /* Wait for the SWRST write to complete.  Cannot rely on SSYNC
  63          * though as the System state is all reset now.
  64          */
  65         asm(
  66                 "LSETUP (1f, 1f) LC1 = %0\n"
  67                 "1: nop;"
  68                 :
  69                 : "a" (15 * 1)
  70                 : "LC1", "LB1", "LT1"
  71         );
  72
  73         while (1)
  74                 /* Issue core reset */
  75                 asm("raise 1");
  76 }
  77
  78 __attribute__((weak))
  79 void native_machine_restart(char *cmd)
  80 {
  81 }
  82
  83 void machine_restart(char *cmd)
  84 {
  85         native_machine_restart(cmd);
  86         local_irq_disable();
  87         if (smp_processor_id())
  88                 smp_call_function((void *)bfin_reset, 0, 1);
  89         else
  90                 bfin_reset();
  91 }
  92
  93 __attribute__((weak))
  94 void native_machine_halt(void)
  95 {
  96         idle_with_irq_disabled();
  97 }
  98
  99 void machine_halt(void)
 100 {
 101         native_machine_halt();
 102 }
 103
 104 __attribute__((weak))
 105 void native_machine_power_off(void)
 106 {
 107         idle_with_irq_disabled();
 108 }
 109
 110 void machine_power_off(void)
 111 {
 112         native_machine_power_off();
 113 }