drivers/s390/char/sclp_quiesce.c

   1 /*
   2  *  drivers/s390/char/sclp_quiesce.c
   3  *     signal quiesce handler
   4  *
   5  *  (C) Copyright IBM Corp. 1999,2004
   6  *  Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
   7  *             Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
   8  */
   9
  10 #include <linux/config.h>
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/cpumask.h>
  14 #include <linux/smp.h>
  15 #include <linux/init.h>
  16 #include <linux/reboot.h>
  17 #include <asm/atomic.h>
  18 #include <asm/ptrace.h>
  19 #include <asm/sigp.h>
  20
  21 #include "sclp.h"
  22
  23
  24 #ifdef CONFIG_SMP
  25 /* Signal completion of shutdown process. All CPUs except the first to enter
  26  * this function: go to stopped state. First CPU: wait until all other
  27  * CPUs are in stopped or check stop state. Afterwards, load special PSW
  28  * to indicate completion. */
  29 static void
  30 do_load_quiesce_psw(void * __unused)
  31 {
  32         static atomic_t cpuid = ATOMIC_INIT(-1);
  33         psw_t quiesce_psw;
  34         int cpu;
  35
  36         if (atomic_cmpxchg(&cpuid, -1, smp_processor_id()) != -1)
  37                 signal_processor(smp_processor_id(), sigp_stop);
  38         /* Wait for all other cpus to enter stopped state */
  39         for_each_online_cpu(cpu) {
  40                 if (cpu == smp_processor_id())
  41                         continue;
  42                 while(!smp_cpu_not_running(cpu))
  43                         cpu_relax();
  44         }
  45         /* Quiesce the last cpu with the special psw */
  46         quiesce_psw.mask = PSW_BASE_BITS | PSW_MASK_WAIT;
  47         quiesce_psw.addr = 0xfff;
  48         __load_psw(quiesce_psw);
  49 }
  50
  51 /* Shutdown handler. Perform shutdown function on all CPUs. */
  52 static void
  53 do_machine_quiesce(void)
  54 {
  55         on_each_cpu(do_load_quiesce_psw, NULL, 0, 0);
  56 }
  57 #else
  58 /* Shutdown handler. Signal completion of shutdown by loading special PSW. */
  59 static void
  60 do_machine_quiesce(void)
  61 {
  62         psw_t quiesce_psw;
  63
  64         quiesce_psw.mask = PSW_BASE_BITS | PSW_MASK_WAIT;
  65         quiesce_psw.addr = 0xfff;
  66         __load_psw(quiesce_psw);
  67 }
  68 #endif
  69
  70 /* Handler for quiesce event. Start shutdown procedure. */
  71 static void
  72 sclp_quiesce_handler(struct evbuf_header *evbuf)
  73 {
  74         _machine_restart = (void *) do_machine_quiesce;
  75         _machine_halt = do_machine_quiesce;
  76         _machine_power_off = do_machine_quiesce;
  77         ctrl_alt_del();
  78 }
  79
  80 static struct sclp_register sclp_quiesce_event = {
  81         .receive_mask = EvTyp_SigQuiesce_Mask,
  82         .receiver_fn = sclp_quiesce_handler
  83 };
  84
  85 /* Initialize quiesce driver. */
  86 static int __init
  87 sclp_quiesce_init(void)
  88 {
  89         int rc;
  90
  91         rc = sclp_register(&sclp_quiesce_event);
  92         if (rc)
  93                 printk(KERN_WARNING "sclp: could not register quiesce handler "
  94                        "(rc=%d)\n", rc);
  95         return rc;
  96 }
  97
  98 module_init(sclp_quiesce_init);