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