/*
   * Handle extern requests for shutdown, reboot and sysrq
   */
  #include <linux/kernel.h>
  #include <linux/err.h>

  #include <linux/slab.h>

  #include <linux/reboot.h>
  #include <linux/sysrq.h>

  #include <linux/stop_machine.h>
  #include <linux/freezer.h>

  #include <linux/syscore_ops.h>

  #include <linux/export.h>

  #include <xen/xen.h>

  #include <xen/xenbus.h>

  #include <xen/grant_table.h>
  #include <xen/events.h>
  #include <xen/hvc-console.h>
  #include <xen/xen-ops.h>

  #include <asm/xen/hypercall.h>
  #include <asm/xen/page.h>

  #include <asm/xen/hypervisor.h>

  
  enum shutdown_state {
  	SHUTDOWN_INVALID = -1,
  	SHUTDOWN_POWEROFF = 0,
  	SHUTDOWN_SUSPEND = 2,
  	/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
  	   report a crash, not be instructed to crash!
  	   HALT is the same as POWEROFF, as far as we're concerned.  The tools use
  	   the distinction when we return the reason code to them.  */
  	 SHUTDOWN_HALT = 4,
  };

  
  /* Ignore multiple shutdown requests. */

  static enum shutdown_state shutting_down = SHUTDOWN_INVALID;

  struct suspend_info {
  	int cancelled;

  	unsigned long arg; /* extra hypercall argument */

  	void (*pre)(void);
  	void (*post)(int cancelled);

  };

  static void xen_hvm_post_suspend(int cancelled)

  {

  	xen_arch_hvm_post_suspend(cancelled);

  	gnttab_resume();
  }
  
  static void xen_pre_suspend(void)
  {
  	xen_mm_pin_all();
  	gnttab_suspend();

  	xen_arch_pre_suspend();

  }

  static void xen_post_suspend(int cancelled)

  {

  	xen_arch_post_suspend(cancelled);

  	gnttab_resume();
  	xen_mm_unpin_all();
  }

  #ifdef CONFIG_HIBERNATE_CALLBACKS

  static int xen_suspend(void *data)
  {

  	struct suspend_info *si = data;

  	int err;

  
  	BUG_ON(!irqs_disabled());

  	err = syscore_suspend();

  	if (err) {

  		printk(KERN_ERR "xen_suspend: system core suspend failed: %d
  ",

  			err);

  		return err;
  	}

  	if (si->pre)
  		si->pre();

  
  	/*
  	 * This hypercall returns 1 if suspend was cancelled
  	 * or the domain was merely checkpointed, and 0 if it
  	 * is resuming in a new domain.
  	 */

  	si->cancelled = HYPERVISOR_suspend(si->arg);

  	if (si->post)
  		si->post(si->cancelled);

  	if (!si->cancelled) {

  		xen_irq_resume();
  		xen_console_resume();

  		xen_timer_resume();

  	}

  	syscore_resume();

  	return 0;
  }
  
  static void do_suspend(void)
  {
  	int err;

  	struct suspend_info si;

  
  	shutting_down = SHUTDOWN_SUSPEND;
  
  #ifdef CONFIG_PREEMPT
  	/* If the kernel is preemptible, we need to freeze all the processes
  	   to prevent them from being in the middle of a pagetable update
  	   during suspend. */
  	err = freeze_processes();
  	if (err) {
  		printk(KERN_ERR "xen suspend: freeze failed %d
  ", err);

  		goto out;

  	}
  #endif

  	err = dpm_suspend_start(PMSG_FREEZE);

  	if (err) {

  		printk(KERN_ERR "xen suspend: dpm_suspend_start %d
  ", err);

  		goto out_thaw;

  	}

  	printk(KERN_DEBUG "suspending xenstore...
  ");
  	xs_suspend();

  	err = dpm_suspend_noirq(PMSG_FREEZE);

  	if (err) {

  		printk(KERN_ERR "dpm_suspend_noirq failed: %d
  ", err);

  		goto out_resume;

  	}

  	si.cancelled = 1;

  	if (xen_hvm_domain()) {

  		si.arg = 0UL;

  		si.pre = NULL;
  		si.post = &xen_hvm_post_suspend;
  	} else {

  		si.arg = virt_to_mfn(xen_start_info);

  		si.pre = &xen_pre_suspend;
  		si.post = &xen_post_suspend;
  	}

  	err = stop_machine(xen_suspend, &si, cpumask_of(0));

  	dpm_resume_noirq(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

  	if (err) {
  		printk(KERN_ERR "failed to start xen_suspend: %d
  ", err);

  		si.cancelled = 1;

  	}

  out_resume:

  	if (!si.cancelled) {

  		xen_arch_resume();

  		xs_resume();

  	} else

  		xs_suspend_cancel();

  	dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

  	/* Make sure timer events get retriggered on all CPUs */
  	clock_was_set();

  
  out_thaw:

  #ifdef CONFIG_PREEMPT
  	thaw_processes();

  out:

  #endif

  	shutting_down = SHUTDOWN_INVALID;
  }

  #endif	/* CONFIG_HIBERNATE_CALLBACKS */

  struct shutdown_handler {
  	const char *command;
  	void (*cb)(void);
  };
  
  static void do_poweroff(void)
  {
  	shutting_down = SHUTDOWN_POWEROFF;
  	orderly_poweroff(false);
  }
  
  static void do_reboot(void)
  {
  	shutting_down = SHUTDOWN_POWEROFF; /* ? */
  	ctrl_alt_del();
  }

  static void shutdown_handler(struct xenbus_watch *watch,
  			     const char **vec, unsigned int len)
  {
  	char *str;
  	struct xenbus_transaction xbt;
  	int err;

  	static struct shutdown_handler handlers[] = {
  		{ "poweroff",	do_poweroff },
  		{ "halt",	do_poweroff },
  		{ "reboot",	do_reboot   },

  #ifdef CONFIG_HIBERNATE_CALLBACKS

  		{ "suspend",	do_suspend  },
  #endif
  		{NULL, NULL},
  	};
  	static struct shutdown_handler *handler;

  
  	if (shutting_down != SHUTDOWN_INVALID)
  		return;
  
   again:
  	err = xenbus_transaction_start(&xbt);
  	if (err)
  		return;
  
  	str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
  	/* Ignore read errors and empty reads. */
  	if (XENBUS_IS_ERR_READ(str)) {
  		xenbus_transaction_end(xbt, 1);
  		return;
  	}

  	for (handler = &handlers[0]; handler->command; handler++) {
  		if (strcmp(str, handler->command) == 0)
  			break;
  	}
  
  	/* Only acknowledge commands which we are prepared to handle. */
  	if (handler->cb)
  		xenbus_write(xbt, "control", "shutdown", "");

  
  	err = xenbus_transaction_end(xbt, 0);
  	if (err == -EAGAIN) {
  		kfree(str);
  		goto again;
  	}

  	if (handler->cb) {
  		handler->cb();

  	} else {

  		printk(KERN_INFO "Ignoring shutdown request: %s
  ", str);
  		shutting_down = SHUTDOWN_INVALID;
  	}
  
  	kfree(str);
  }

  #ifdef CONFIG_MAGIC_SYSRQ

  static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
  			  unsigned int len)
  {
  	char sysrq_key = '\0';
  	struct xenbus_transaction xbt;
  	int err;
  
   again:
  	err = xenbus_transaction_start(&xbt);
  	if (err)
  		return;
  	if (!xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key)) {
  		printk(KERN_ERR "Unable to read sysrq code in "
  		       "control/sysrq
  ");
  		xenbus_transaction_end(xbt, 1);
  		return;
  	}
  
  	if (sysrq_key != '\0')
  		xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
  
  	err = xenbus_transaction_end(xbt, 0);
  	if (err == -EAGAIN)
  		goto again;
  
  	if (sysrq_key != '\0')

  		handle_sysrq(sysrq_key);

  }

  static struct xenbus_watch sysrq_watch = {
  	.node = "control/sysrq",
  	.callback = sysrq_handler
  };

  #endif
  
  static struct xenbus_watch shutdown_watch = {
  	.node = "control/shutdown",
  	.callback = shutdown_handler
  };

  
  static int setup_shutdown_watcher(void)
  {
  	int err;
  
  	err = register_xenbus_watch(&shutdown_watch);
  	if (err) {
  		printk(KERN_ERR "Failed to set shutdown watcher
  ");
  		return err;
  	}

  #ifdef CONFIG_MAGIC_SYSRQ

  	err = register_xenbus_watch(&sysrq_watch);
  	if (err) {
  		printk(KERN_ERR "Failed to set sysrq watcher
  ");
  		return err;
  	}

  #endif

  
  	return 0;
  }
  
  static int shutdown_event(struct notifier_block *notifier,
  			  unsigned long event,
  			  void *data)
  {
  	setup_shutdown_watcher();
  	return NOTIFY_DONE;
  }

  int xen_setup_shutdown_event(void)

  {
  	static struct notifier_block xenstore_notifier = {
  		.notifier_call = shutdown_event
  	};

  
  	if (!xen_domain())
  		return -ENODEV;

  	register_xenstore_notifier(&xenstore_notifier);
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);

  subsys_initcall(xen_setup_shutdown_event);