drivers/cpuidle/cpuidle-powernv.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  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>
 #include <asm/cpuidle.h>

 /*
  * Expose only those Hardware idle states via the cpuidle framework
  * that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
  */
 #define POWERNV_THRESHOLD_LATENCY_NS 200000

 static struct cpuidle_driver powernv_idle_driver = {
 	.name             = "powernv_idle",
 	.owner            = THIS_MODULE,
 };

 static int max_idle_state __read_mostly;
 static struct cpuidle_state *cpuidle_state_table __read_mostly;

 struct stop_psscr_table {
 	u64 val;
 	u64 mask;
 };

 static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;

 static u64 default_snooze_timeout __read_mostly;
 static bool snooze_timeout_en __read_mostly;

 static u64 get_snooze_timeout(struct cpuidle_device *dev,
 			      struct cpuidle_driver *drv,
 			      int index)
 {
 	int i;

 	if (unlikely(!snooze_timeout_en))
 		return default_snooze_timeout;

 	for (i = index + 1; i < drv->state_count; i++) {
 		struct cpuidle_state *s = &drv->states[i];
 		struct cpuidle_state_usage *su = &dev->states_usage[i];

 		if (s->disabled || su->disable)
 			continue;

 		return s->target_residency * tb_ticks_per_usec;
 	}

 	return default_snooze_timeout;
 }

 static int snooze_loop(struct cpuidle_device *dev,
 			struct cpuidle_driver *drv,
 			int index)
 {
 	u64 snooze_exit_time;

 	set_thread_flag(TIF_POLLING_NRFLAG);

 	local_irq_enable();

 	snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
 	ppc64_runlatch_off();
 	HMT_very_low();
 	while (!need_resched()) {
 		if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
 			/*
 			 * Task has not woken up but we are exiting the polling
 			 * loop anyway. Require a barrier after polling is
 			 * cleared to order subsequent test of need_resched().
 			 */
 			clear_thread_flag(TIF_POLLING_NRFLAG);
 			smp_mb();
 			break;
 		}
 	}

 	HMT_medium();
 	ppc64_runlatch_on();
 	clear_thread_flag(TIF_POLLING_NRFLAG);

 	local_irq_disable();

 	return index;
 }

 static int nap_loop(struct cpuidle_device *dev,
 			struct cpuidle_driver *drv,
 			int index)
 {
 	power7_idle_type(PNV_THREAD_NAP);

 	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_idle_type(PNV_THREAD_SLEEP);

 	mtspr(SPRN_LPCR, old_lpcr);

 	return index;
 }
 #endif

 static int stop_loop(struct cpuidle_device *dev,
 		     struct cpuidle_driver *drv,
 		     int index)
 {
 	power9_idle_type(stop_psscr_table[index].val,
 			 stop_psscr_table[index].mask);
 	return index;
 }

 /*
  * States for dedicated partition case.
  */
 static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
 	{ /* Snooze */
 		.name = "snooze",
 		.desc = "snooze",
 		.exit_latency = 0,
 		.target_residency = 0,
 		.enter = snooze_loop },
 };

 static int powernv_cpuidle_cpu_online(unsigned int cpu)
 {
 	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);

 	if (dev && cpuidle_get_driver()) {
 		cpuidle_pause_and_lock();
 		cpuidle_enable_device(dev);
 		cpuidle_resume_and_unlock();
 	}
 	return 0;
 }

 static int powernv_cpuidle_cpu_dead(unsigned int cpu)
 {
 	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);

 	if (dev && cpuidle_get_driver()) {
 		cpuidle_pause_and_lock();
 		cpuidle_disable_device(dev);
 		cpuidle_resume_and_unlock();
 	}
 	return 0;
 }

 /*
  * 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;
 	}

 	/*
 	 * On the PowerNV platform cpu_present may be less than cpu_possible in
 	 * cases when firmware detects the CPU, but it is not available to the
 	 * OS.  If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
 	 * run time and hence cpu_devices are not created for those CPUs by the
 	 * generic topology_init().
 	 *
 	 * drv->cpumask defaults to cpu_possible_mask in
 	 * __cpuidle_driver_init().  This breaks cpuidle on PowerNV where
 	 * cpu_devices are not created for CPUs in cpu_possible_mask that
 	 * cannot be hot-added later at run time.
 	 *
 	 * Trying cpuidle_register_device() on a CPU without a cpu_device is
 	 * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
 	 */

 	drv->cpumask = (struct cpumask *)cpu_present_mask;

 	return 0;
 }

 static inline void add_powernv_state(int index, const char *name,
 				     unsigned int flags,
 				     int (*idle_fn)(struct cpuidle_device *,
 						    struct cpuidle_driver *,
 						    int),
 				     unsigned int target_residency,
 				     unsigned int exit_latency,
 				     u64 psscr_val, u64 psscr_mask)
 {
 	strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
 	strlcpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
 	powernv_states[index].flags = flags;
 	powernv_states[index].target_residency = target_residency;
 	powernv_states[index].exit_latency = exit_latency;
 	powernv_states[index].enter = idle_fn;
 	stop_psscr_table[index].val = psscr_val;
 	stop_psscr_table[index].mask = psscr_mask;
 }

 /*
  * Returns 0 if prop1_len == prop2_len. Else returns -1
  */
 static inline int validate_dt_prop_sizes(const char *prop1, int prop1_len,
 					 const char *prop2, int prop2_len)
 {
 	if (prop1_len == prop2_len)
 		return 0;

 	pr_warn("cpuidle-powernv: array sizes don't match for %s and %s\n",
 		prop1, prop2);
 	return -1;
 }

 extern u32 pnv_get_supported_cpuidle_states(void);
 static int powernv_add_idle_states(void)
 {
 	struct device_node *power_mgt;
 	int nr_idle_states = 1; /* Snooze */
 	int dt_idle_states, count;
 	u32 latency_ns[CPUIDLE_STATE_MAX];
 	u32 residency_ns[CPUIDLE_STATE_MAX];
 	u32 flags[CPUIDLE_STATE_MAX];
 	u64 psscr_val[CPUIDLE_STATE_MAX];
 	u64 psscr_mask[CPUIDLE_STATE_MAX];
 	const char *names[CPUIDLE_STATE_MAX];
 	u32 has_stop_states = 0;
 	int i, rc;
 	u32 supported_flags = pnv_get_supported_cpuidle_states();


 	/* 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\n");
 		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\n");
 		goto out;
 	}

 	count = of_property_count_u32_elems(power_mgt,
 					    "ibm,cpu-idle-state-latencies-ns");

 	if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags", dt_idle_states,
 				   "ibm,cpu-idle-state-latencies-ns",
 				   count) != 0)
 		goto out;

 	count = of_property_count_strings(power_mgt,
 					  "ibm,cpu-idle-state-names");
 	if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags", dt_idle_states,
 				   "ibm,cpu-idle-state-names",
 				   count) != 0)
 		goto out;

 	/*
 	 * Since snooze is used as first idle state, max idle states allowed is
 	 * CPUIDLE_STATE_MAX -1
 	 */
 	if (dt_idle_states > CPUIDLE_STATE_MAX - 1) {
 		pr_warn("cpuidle-powernv: discovered idle states more than allowed");
 		dt_idle_states = CPUIDLE_STATE_MAX - 1;
 	}

 	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\n");
 		goto out;
 	}

 	if (of_property_read_u32_array(power_mgt,
 		"ibm,cpu-idle-state-latencies-ns", latency_ns,
 		dt_idle_states)) {
 		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
 		goto out;
 	}
 	if (of_property_read_string_array(power_mgt,
 		"ibm,cpu-idle-state-names", names, dt_idle_states) < 0) {
 		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-names in DT\n");
 		goto out;
 	}

 	/*
 	 * If the idle states use stop instruction, probe for psscr values
 	 * and psscr mask which are necessary to specify required stop level.
 	 */
 	has_stop_states = (flags[0] &
 			   (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
 	if (has_stop_states) {
 		count = of_property_count_u64_elems(power_mgt,
 						    "ibm,cpu-idle-state-psscr");
 		if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags",
 					   dt_idle_states,
 					   "ibm,cpu-idle-state-psscr",
 					   count) != 0)
 			goto out;

 		count = of_property_count_u64_elems(power_mgt,
 						    "ibm,cpu-idle-state-psscr-mask");
 		if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags",
 					   dt_idle_states,
 					   "ibm,cpu-idle-state-psscr-mask",
 					   count) != 0)
 			goto out;

 		if (of_property_read_u64_array(power_mgt,
 		    "ibm,cpu-idle-state-psscr", psscr_val, dt_idle_states)) {
 			pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-psscr in DT\n");
 			goto out;
 		}

 		if (of_property_read_u64_array(power_mgt,
 					       "ibm,cpu-idle-state-psscr-mask",
 						psscr_mask, dt_idle_states)) {
 			pr_warn("cpuidle-powernv:Missing ibm,cpu-idle-state-psscr-mask in DT\n");
 			goto out;
 		}
 	}

 	count = of_property_count_u32_elems(power_mgt,
 					    "ibm,cpu-idle-state-residency-ns");

 	if (count < 0) {
 		rc = count;
 	} else if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags",
 					  dt_idle_states,
 					  "ibm,cpu-idle-state-residency-ns",
 					  count) != 0) {
 		goto out;
 	} else {
 		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++) {
 		unsigned int exit_latency, target_residency;
 		bool stops_timebase = false;

 		/*
 		 * Skip the platform idle state whose flag isn't in
 		 * the supported_cpuidle_states flag mask.
 		 */
 		if ((flags[i] & supported_flags) != flags[i])
 			continue;
 		/*
 		 * If an idle state has exit latency beyond
 		 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
 		 * in cpu-idle.
 		 */
 		if (latency_ns[i] > POWERNV_THRESHOLD_LATENCY_NS)
 			continue;
 		/*
 		 * Firmware passes residency and latency values in ns.
 		 * cpuidle expects it in us.
 		 */
 		exit_latency = DIV_ROUND_UP(latency_ns[i], 1000);
 		if (!rc)
 			target_residency = DIV_ROUND_UP(residency_ns[i], 1000);
 		else
 			target_residency = 0;

 		if (has_stop_states) {
 			int err = validate_psscr_val_mask(&psscr_val[i],
 							  &psscr_mask[i],
 							  flags[i]);
 			if (err) {
 				report_invalid_psscr_val(psscr_val[i], err);
 				continue;
 			}
 		}

 		if (flags[i] & OPAL_PM_TIMEBASE_STOP)
 			stops_timebase = true;

 		/*
 		 * For nap and fastsleep, use default target_residency
 		 * values if f/w does not expose it.
 		 */
 		if (flags[i] & OPAL_PM_NAP_ENABLED) {
 			if (!rc)
 				target_residency = 100;
 			/* Add NAP state */
 			add_powernv_state(nr_idle_states, "Nap",
 					  CPUIDLE_FLAG_NONE, nap_loop,
 					  target_residency, exit_latency, 0, 0);
 		} else if (has_stop_states && !stops_timebase) {
 			add_powernv_state(nr_idle_states, names[i],
 					  CPUIDLE_FLAG_NONE, stop_loop,
 					  target_residency, exit_latency,
 					  psscr_val[i], psscr_mask[i]);
 		}

 		/*
 		 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
 		 * within this config dependency check.
 		 */
 #ifdef CONFIG_TICK_ONESHOT
 		else if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
 			 flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
 			if (!rc)
 				target_residency = 300000;
 			/* Add FASTSLEEP state */
 			add_powernv_state(nr_idle_states, "FastSleep",
 					  CPUIDLE_FLAG_TIMER_STOP,
 					  fastsleep_loop,
 					  target_residency, exit_latency, 0, 0);
 		} else if (has_stop_states && stops_timebase) {
 			add_powernv_state(nr_idle_states, names[i],
 					  CPUIDLE_FLAG_TIMER_STOP, stop_loop,
 					  target_residency, exit_latency,
 					  psscr_val[i], psscr_mask[i]);
 		}
 #endif
 		else
 			continue;
 		nr_idle_states++;
 	}
 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_OPAL)) {
 		cpuidle_state_table = powernv_states;
 		/* Device tree can indicate more idle states */
 		max_idle_state = powernv_add_idle_states();
 		default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
 		if (max_idle_state > 1)
 			snooze_timeout_en = true;
  	} 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.\n");
 		return retval;
 	}

 	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 					   "cpuidle/powernv:online",
 					   powernv_cpuidle_cpu_online, NULL);
 	WARN_ON(retval < 0);
 	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
 					   "cpuidle/powernv:dead", NULL,
 					   powernv_cpuidle_cpu_dead);
 	WARN_ON(retval < 0);
 	printk(KERN_DEBUG "powernv_idle_driver registered\n");
 	return 0;
 }

 device_initcall(powernv_processor_idle_init);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 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>
	#include <asm/cpuidle.h>

	/*
	* Expose only those Hardware idle states via the cpuidle framework
	* that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
	*/
	#define POWERNV_THRESHOLD_LATENCY_NS 200000

	static struct cpuidle_driver powernv_idle_driver = {
	.name = "powernv_idle",
	.owner = THIS_MODULE,
	};

	static int max_idle_state __read_mostly;
	static struct cpuidle_state *cpuidle_state_table __read_mostly;

	struct stop_psscr_table {
	u64 val;
	u64 mask;
	};

	static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;

	static u64 default_snooze_timeout __read_mostly;
	static bool snooze_timeout_en __read_mostly;

	static u64 get_snooze_timeout(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int index)
	{
	int i;

	if (unlikely(!snooze_timeout_en))
	return default_snooze_timeout;

	for (i = index + 1; i < drv->state_count; i++) {
	struct cpuidle_state *s = &drv->states[i];
	struct cpuidle_state_usage *su = &dev->states_usage[i];

	if (s->disabled \|\| su->disable)
	continue;

	return s->target_residency * tb_ticks_per_usec;
	}

	return default_snooze_timeout;
	}

	static int snooze_loop(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int index)
	{
	u64 snooze_exit_time;

	set_thread_flag(TIF_POLLING_NRFLAG);

	local_irq_enable();

	snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
	ppc64_runlatch_off();
	HMT_very_low();
	while (!need_resched()) {
	if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
	/*
	* Task has not woken up but we are exiting the polling
	* loop anyway. Require a barrier after polling is
	* cleared to order subsequent test of need_resched().
	*/
	clear_thread_flag(TIF_POLLING_NRFLAG);
	smp_mb();
	break;
	}
	}

	HMT_medium();
	ppc64_runlatch_on();
	clear_thread_flag(TIF_POLLING_NRFLAG);

	local_irq_disable();

	return index;
	}

	static int nap_loop(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int index)
	{
	power7_idle_type(PNV_THREAD_NAP);

	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_idle_type(PNV_THREAD_SLEEP);

	mtspr(SPRN_LPCR, old_lpcr);

	return index;
	}
	#endif

	static int stop_loop(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int index)
	{
	power9_idle_type(stop_psscr_table[index].val,
	stop_psscr_table[index].mask);
	return index;
	}

	/*
	* States for dedicated partition case.
	*/
	static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
	{ /* Snooze */
	.name = "snooze",
	.desc = "snooze",
	.exit_latency = 0,
	.target_residency = 0,
	.enter = snooze_loop },
	};

	static int powernv_cpuidle_cpu_online(unsigned int cpu)
	{
	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);

	if (dev && cpuidle_get_driver()) {
	cpuidle_pause_and_lock();
	cpuidle_enable_device(dev);
	cpuidle_resume_and_unlock();
	}
	return 0;
	}

	static int powernv_cpuidle_cpu_dead(unsigned int cpu)
	{
	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);

	if (dev && cpuidle_get_driver()) {
	cpuidle_pause_and_lock();
	cpuidle_disable_device(dev);
	cpuidle_resume_and_unlock();
	}
	return 0;
	}

	/*
	* 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;
	}

	/*
	* On the PowerNV platform cpu_present may be less than cpu_possible in
	* cases when firmware detects the CPU, but it is not available to the
	* OS. If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
	* run time and hence cpu_devices are not created for those CPUs by the
	* generic topology_init().
	*
	* drv->cpumask defaults to cpu_possible_mask in
	* __cpuidle_driver_init(). This breaks cpuidle on PowerNV where
	* cpu_devices are not created for CPUs in cpu_possible_mask that
	* cannot be hot-added later at run time.
	*
	* Trying cpuidle_register_device() on a CPU without a cpu_device is
	* incorrect, so pass a correct CPU mask to the generic cpuidle driver.
	*/

	drv->cpumask = (struct cpumask *)cpu_present_mask;

	return 0;
	}

	static inline void add_powernv_state(int index, const char *name,
	unsigned int flags,
	int (idle_fn)(struct cpuidle_device ,
	struct cpuidle_driver *,
	int),
	unsigned int target_residency,
	unsigned int exit_latency,
	u64 psscr_val, u64 psscr_mask)
	{
	strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
	strlcpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
	powernv_states[index].flags = flags;
	powernv_states[index].target_residency = target_residency;
	powernv_states[index].exit_latency = exit_latency;
	powernv_states[index].enter = idle_fn;
	stop_psscr_table[index].val = psscr_val;
	stop_psscr_table[index].mask = psscr_mask;
	}

	/*
	* Returns 0 if prop1_len == prop2_len. Else returns -1
	*/
	static inline int validate_dt_prop_sizes(const char *prop1, int prop1_len,
	const char *prop2, int prop2_len)
	{
	if (prop1_len == prop2_len)
	return 0;

	pr_warn("cpuidle-powernv: array sizes don't match for %s and %s\n",
	prop1, prop2);
	return -1;
	}

	extern u32 pnv_get_supported_cpuidle_states(void);
	static int powernv_add_idle_states(void)
	{
	struct device_node *power_mgt;
	int nr_idle_states = 1; /* Snooze */
	int dt_idle_states, count;
	u32 latency_ns[CPUIDLE_STATE_MAX];
	u32 residency_ns[CPUIDLE_STATE_MAX];
	u32 flags[CPUIDLE_STATE_MAX];
	u64 psscr_val[CPUIDLE_STATE_MAX];
	u64 psscr_mask[CPUIDLE_STATE_MAX];
	const char *names[CPUIDLE_STATE_MAX];
	u32 has_stop_states = 0;
	int i, rc;
	u32 supported_flags = pnv_get_supported_cpuidle_states();


	/* 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\n");
	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\n");
	goto out;
	}

	count = of_property_count_u32_elems(power_mgt,
	"ibm,cpu-idle-state-latencies-ns");

	if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags", dt_idle_states,
	"ibm,cpu-idle-state-latencies-ns",
	count) != 0)
	goto out;

	count = of_property_count_strings(power_mgt,
	"ibm,cpu-idle-state-names");
	if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags", dt_idle_states,
	"ibm,cpu-idle-state-names",
	count) != 0)
	goto out;

	/*
	* Since snooze is used as first idle state, max idle states allowed is
	* CPUIDLE_STATE_MAX -1
	*/
	if (dt_idle_states > CPUIDLE_STATE_MAX - 1) {
	pr_warn("cpuidle-powernv: discovered idle states more than allowed");
	dt_idle_states = CPUIDLE_STATE_MAX - 1;
	}

	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\n");
	goto out;
	}

	if (of_property_read_u32_array(power_mgt,
	"ibm,cpu-idle-state-latencies-ns", latency_ns,
	dt_idle_states)) {
	pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
	goto out;
	}
	if (of_property_read_string_array(power_mgt,
	"ibm,cpu-idle-state-names", names, dt_idle_states) < 0) {
	pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-names in DT\n");
	goto out;
	}

	/*
	* If the idle states use stop instruction, probe for psscr values
	* and psscr mask which are necessary to specify required stop level.
	*/
	has_stop_states = (flags[0] &
	(OPAL_PM_STOP_INST_FAST \| OPAL_PM_STOP_INST_DEEP));
	if (has_stop_states) {
	count = of_property_count_u64_elems(power_mgt,
	"ibm,cpu-idle-state-psscr");
	if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags",
	dt_idle_states,
	"ibm,cpu-idle-state-psscr",
	count) != 0)
	goto out;

	count = of_property_count_u64_elems(power_mgt,
	"ibm,cpu-idle-state-psscr-mask");
	if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags",
	dt_idle_states,
	"ibm,cpu-idle-state-psscr-mask",
	count) != 0)
	goto out;

	if (of_property_read_u64_array(power_mgt,
	"ibm,cpu-idle-state-psscr", psscr_val, dt_idle_states)) {
	pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-psscr in DT\n");
	goto out;
	}

	if (of_property_read_u64_array(power_mgt,
	"ibm,cpu-idle-state-psscr-mask",
	psscr_mask, dt_idle_states)) {
	pr_warn("cpuidle-powernv:Missing ibm,cpu-idle-state-psscr-mask in DT\n");
	goto out;
	}
	}

	count = of_property_count_u32_elems(power_mgt,
	"ibm,cpu-idle-state-residency-ns");

	if (count < 0) {
	rc = count;
	} else if (validate_dt_prop_sizes("ibm,cpu-idle-state-flags",
	dt_idle_states,
	"ibm,cpu-idle-state-residency-ns",
	count) != 0) {
	goto out;
	} else {
	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++) {
	unsigned int exit_latency, target_residency;
	bool stops_timebase = false;

	/*
	* Skip the platform idle state whose flag isn't in
	* the supported_cpuidle_states flag mask.
	*/
	if ((flags[i] & supported_flags) != flags[i])
	continue;
	/*
	* If an idle state has exit latency beyond
	* POWERNV_THRESHOLD_LATENCY_NS then don't use it
	* in cpu-idle.
	*/
	if (latency_ns[i] > POWERNV_THRESHOLD_LATENCY_NS)
	continue;
	/*
	* Firmware passes residency and latency values in ns.
	* cpuidle expects it in us.
	*/
	exit_latency = DIV_ROUND_UP(latency_ns[i], 1000);
	if (!rc)
	target_residency = DIV_ROUND_UP(residency_ns[i], 1000);
	else
	target_residency = 0;

	if (has_stop_states) {
	int err = validate_psscr_val_mask(&psscr_val[i],
	&psscr_mask[i],
	flags[i]);
	if (err) {
	report_invalid_psscr_val(psscr_val[i], err);
	continue;
	}
	}

	if (flags[i] & OPAL_PM_TIMEBASE_STOP)
	stops_timebase = true;

	/*
	* For nap and fastsleep, use default target_residency
	* values if f/w does not expose it.
	*/
	if (flags[i] & OPAL_PM_NAP_ENABLED) {
	if (!rc)
	target_residency = 100;
	/* Add NAP state */
	add_powernv_state(nr_idle_states, "Nap",
	CPUIDLE_FLAG_NONE, nap_loop,
	target_residency, exit_latency, 0, 0);
	} else if (has_stop_states && !stops_timebase) {
	add_powernv_state(nr_idle_states, names[i],
	CPUIDLE_FLAG_NONE, stop_loop,
	target_residency, exit_latency,
	psscr_val[i], psscr_mask[i]);
	}

	/*
	* All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
	* within this config dependency check.
	*/
	#ifdef CONFIG_TICK_ONESHOT
	else if (flags[i] & OPAL_PM_SLEEP_ENABLED \|\|
	flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
	if (!rc)
	target_residency = 300000;
	/* Add FASTSLEEP state */
	add_powernv_state(nr_idle_states, "FastSleep",
	CPUIDLE_FLAG_TIMER_STOP,
	fastsleep_loop,
	target_residency, exit_latency, 0, 0);
	} else if (has_stop_states && stops_timebase) {
	add_powernv_state(nr_idle_states, names[i],
	CPUIDLE_FLAG_TIMER_STOP, stop_loop,
	target_residency, exit_latency,
	psscr_val[i], psscr_mask[i]);
	}
	#endif
	else
	continue;
	nr_idle_states++;
	}
	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_OPAL)) {
	cpuidle_state_table = powernv_states;
	/* Device tree can indicate more idle states */
	max_idle_state = powernv_add_idle_states();
	default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
	if (max_idle_state > 1)
	snooze_timeout_en = true;
	} 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.\n");
	return retval;
	}

	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
	"cpuidle/powernv:online",
	powernv_cpuidle_cpu_online, NULL);
	WARN_ON(retval < 0);
	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
	"cpuidle/powernv:dead", NULL,
	powernv_cpuidle_cpu_dead);
	WARN_ON(retval < 0);
	printk(KERN_DEBUG "powernv_idle_driver registered\n");
	return 0;
	}

	device_initcall(powernv_processor_idle_init);