/*
   *  cpuidle-powernv - idle state cpuidle driver.
   *  Adapted from drivers/cpuidle/cpuidle-pseries
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/moduleparam.h>
  #include <linux/cpuidle.h>
  #include <linux/cpu.h>
  #include <linux/notifier.h>
  #include <linux/clockchips.h>
  #include <linux/of.h>
  #include <linux/slab.h>
  
  #include <asm/machdep.h>
  #include <asm/firmware.h>
  #include <asm/opal.h>
  #include <asm/runlatch.h>
  
  #define MAX_POWERNV_IDLE_STATES	8
  
  struct cpuidle_driver powernv_idle_driver = {
  	.name             = "powernv_idle",
  	.owner            = THIS_MODULE,
  };
  
  static int max_idle_state;
  static struct cpuidle_state *cpuidle_state_table;
  static u64 snooze_timeout;
  static bool snooze_timeout_en;
  
  static int snooze_loop(struct cpuidle_device *dev,
  			struct cpuidle_driver *drv,
  			int index)
  {
  	u64 snooze_exit_time;
  
  	local_irq_enable();
  	set_thread_flag(TIF_POLLING_NRFLAG);
  
  	snooze_exit_time = get_tb() + snooze_timeout;
  	ppc64_runlatch_off();
  	while (!need_resched()) {
  		HMT_low();
  		HMT_very_low();
  		if (snooze_timeout_en && get_tb() > snooze_exit_time)
  			break;
  	}
  
  	HMT_medium();
  	ppc64_runlatch_on();
  	clear_thread_flag(TIF_POLLING_NRFLAG);
  	smp_mb();
  	return index;
  }
  
  static int nap_loop(struct cpuidle_device *dev,
  			struct cpuidle_driver *drv,
  			int index)
  {
  	ppc64_runlatch_off();
  	power7_idle();
  	ppc64_runlatch_on();
  	return index;
  }
  
  /* Register for fastsleep only in oneshot mode of broadcast */
  #ifdef CONFIG_TICK_ONESHOT
  static int fastsleep_loop(struct cpuidle_device *dev,
  				struct cpuidle_driver *drv,
  				int index)
  {
  	unsigned long old_lpcr = mfspr(SPRN_LPCR);
  	unsigned long new_lpcr;
  
  	if (unlikely(system_state < SYSTEM_RUNNING))
  		return index;
  
  	new_lpcr = old_lpcr;
  	/* Do not exit powersave upon decrementer as we've setup the timer
  	 * offload.
  	 */
  	new_lpcr &= ~LPCR_PECE1;
  
  	mtspr(SPRN_LPCR, new_lpcr);
  	power7_sleep();
  
  	mtspr(SPRN_LPCR, old_lpcr);
  
  	return index;
  }
  #endif
  /*
   * States for dedicated partition case.
   */
  static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
  	{ /* Snooze */
  		.name = "snooze",
  		.desc = "snooze",
  		.exit_latency = 0,
  		.target_residency = 0,
  		.enter = &snooze_loop },
  };
  
  static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
  			unsigned long action, void *hcpu)
  {
  	int hotcpu = (unsigned long)hcpu;
  	struct cpuidle_device *dev =
  				per_cpu(cpuidle_devices, hotcpu);
  
  	if (dev && cpuidle_get_driver()) {
  		switch (action) {
  		case CPU_ONLINE:
  		case CPU_ONLINE_FROZEN:
  			cpuidle_pause_and_lock();
  			cpuidle_enable_device(dev);
  			cpuidle_resume_and_unlock();
  			break;
  
  		case CPU_DEAD:
  		case CPU_DEAD_FROZEN:
  			cpuidle_pause_and_lock();
  			cpuidle_disable_device(dev);
  			cpuidle_resume_and_unlock();
  			break;
  
  		default:
  			return NOTIFY_DONE;
  		}
  	}
  	return NOTIFY_OK;
  }
  
  static struct notifier_block setup_hotplug_notifier = {
  	.notifier_call = powernv_cpuidle_add_cpu_notifier,
  };
  
  /*
   * powernv_cpuidle_driver_init()
   */
  static int powernv_cpuidle_driver_init(void)
  {
  	int idle_state;
  	struct cpuidle_driver *drv = &powernv_idle_driver;
  
  	drv->state_count = 0;
  
  	for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
  		/* Is the state not enabled? */
  		if (cpuidle_state_table[idle_state].enter == NULL)
  			continue;
  
  		drv->states[drv->state_count] =	/* structure copy */
  			cpuidle_state_table[idle_state];
  
  		drv->state_count += 1;
  	}
  
  	return 0;
  }
  
  static int powernv_add_idle_states(void)
  {
  	struct device_node *power_mgt;
  	int nr_idle_states = 1; /* Snooze */
  	int dt_idle_states;
  	u32 *latency_ns, *residency_ns, *flags;
  	int i, rc;
  
  	/* Currently we have snooze statically defined */
  
  	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
  	if (!power_mgt) {
  		pr_warn("opal: PowerMgmt Node not found
  ");
  		goto out;
  	}
  
  	/* Read values of any property to determine the num of idle states */
  	dt_idle_states = of_property_count_u32_elems(power_mgt, "ibm,cpu-idle-state-flags");
  	if (dt_idle_states < 0) {
  		pr_warn("cpuidle-powernv: no idle states found in the DT
  ");
  		goto out;
  	}
  
  	flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
  	if (of_property_read_u32_array(power_mgt,
  			"ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
  		pr_warn("cpuidle-powernv : missing ibm,cpu-idle-state-flags in DT
  ");
  		goto out_free_flags;
  	}
  
  	latency_ns = kzalloc(sizeof(*latency_ns) * dt_idle_states, GFP_KERNEL);
  	rc = of_property_read_u32_array(power_mgt,
  		"ibm,cpu-idle-state-latencies-ns", latency_ns, dt_idle_states);
  	if (rc) {
  		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT
  ");
  		goto out_free_latency;
  	}
  
  	residency_ns = kzalloc(sizeof(*residency_ns) * dt_idle_states, GFP_KERNEL);
  	rc = of_property_read_u32_array(power_mgt,
  		"ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);
  
  	for (i = 0; i < dt_idle_states; i++) {
  
  		/*
  		 * Cpuidle accepts exit_latency and target_residency in us.
  		 * Use default target_residency values if f/w does not expose it.
  		 */
  		if (flags[i] & OPAL_PM_NAP_ENABLED) {
  			/* Add NAP state */
  			strcpy(powernv_states[nr_idle_states].name, "Nap");
  			strcpy(powernv_states[nr_idle_states].desc, "Nap");
  			powernv_states[nr_idle_states].flags = 0;
  			powernv_states[nr_idle_states].target_residency = 100;
  			powernv_states[nr_idle_states].enter = &nap_loop;
  		}
  
  		/*
  		 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
  		 * within this config dependency check.
  		 */
  #ifdef CONFIG_TICK_ONESHOT
  		if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
  			flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
  			/* Add FASTSLEEP state */
  			strcpy(powernv_states[nr_idle_states].name, "FastSleep");
  			strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
  			powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
  			powernv_states[nr_idle_states].target_residency = 300000;
  			powernv_states[nr_idle_states].enter = &fastsleep_loop;
  		}
  #endif
  		powernv_states[nr_idle_states].exit_latency =
  				((unsigned int)latency_ns[i]) / 1000;
  
  		if (!rc) {
  			powernv_states[nr_idle_states].target_residency =
  				((unsigned int)residency_ns[i]) / 1000;
  		}
  
  		nr_idle_states++;
  	}
  
  	kfree(residency_ns);
  out_free_latency:
  	kfree(latency_ns);
  out_free_flags:
  	kfree(flags);
  out:
  	return nr_idle_states;
  }
  
  /*
   * powernv_idle_probe()
   * Choose state table for shared versus dedicated partition
   */
  static int powernv_idle_probe(void)
  {
  	if (cpuidle_disable != IDLE_NO_OVERRIDE)
  		return -ENODEV;
  
  	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
  		cpuidle_state_table = powernv_states;
  		/* Device tree can indicate more idle states */
  		max_idle_state = powernv_add_idle_states();
  		if (max_idle_state > 1) {
  			snooze_timeout_en = true;
  			snooze_timeout = powernv_states[1].target_residency *
  					 tb_ticks_per_usec;
  		}
   	} else
   		return -ENODEV;
  
  	return 0;
  }
  
  static int __init powernv_processor_idle_init(void)
  {
  	int retval;
  
  	retval = powernv_idle_probe();
  	if (retval)
  		return retval;
  
  	powernv_cpuidle_driver_init();
  	retval = cpuidle_register(&powernv_idle_driver, NULL);
  	if (retval) {
  		printk(KERN_DEBUG "Registration of powernv driver failed.
  ");
  		return retval;
  	}
  
  	register_cpu_notifier(&setup_hotplug_notifier);
  	printk(KERN_DEBUG "powernv_idle_driver registered
  ");
  	return 0;
  }
  
  device_initcall(powernv_processor_idle_init);