linux/arch/powerpc/platforms/powernv/idle.c

/*
 * PowerNV cpuidle code
 *
 * Copyright 2015 IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/device.h>
#include <linux/cpu.h>

#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/opal.h>
#include <asm/cputhreads.h>
#include <asm/cpuidle.h>
#include <asm/code-patching.h>
#include <asm/smp.h>
#include <asm/runlatch.h>
#include <asm/dbell.h>

#include "powernv.h"
#include "subcore.h"

/* Power ISA 3.0 allows for stop states 0x0 - 0xF */
#define MAX_STOP_STATE	0xF

#define P9_STOP_SPR_MSR 2000
#define P9_STOP_SPR_PSSCR      855

static u32 supported_cpuidle_states;
struct pnv_idle_states_t *pnv_idle_states;
int nr_pnv_idle_states;

/*
 * The default stop state that will be used by ppc_md.power_save
 * function on platforms that support stop instruction.
 */
static u64 pnv_default_stop_val;
static u64 pnv_default_stop_mask;
static bool default_stop_found;

/*
 * First deep stop state. Used to figure out when to save/restore
 * hypervisor context.
 */
u64 pnv_first_deep_stop_state = MAX_STOP_STATE;

/*
 * psscr value and mask of the deepest stop idle state.
 * Used when a cpu is offlined.
 */
static u64 pnv_deepest_stop_psscr_val;
static u64 pnv_deepest_stop_psscr_mask;
static u64 pnv_deepest_stop_flag;
static bool deepest_stop_found;

static int pnv_save_sprs_for_deep_states(void)
{
	int cpu;
	int rc;

	/*
	 * hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric across
	 * all cpus at boot. Get these reg values of current cpu and use the
	 * same across all cpus.
	 */
	uint64_t lpcr_val = mfspr(SPRN_LPCR);
	uint64_t hid0_val = mfspr(SPRN_HID0);
	uint64_t hid1_val = mfspr(SPRN_HID1);
	uint64_t hid4_val = mfspr(SPRN_HID4);
	uint64_t hid5_val = mfspr(SPRN_HID5);
	uint64_t hmeer_val = mfspr(SPRN_HMEER);
	uint64_t msr_val = MSR_IDLE;
	uint64_t psscr_val = pnv_deepest_stop_psscr_val;

	for_each_present_cpu(cpu) {
		uint64_t pir = get_hard_smp_processor_id(cpu);
		uint64_t hsprg0_val = (uint64_t)paca_ptrs[cpu];

		rc = opal_slw_set_reg(pir, SPRN_HSPRG0, hsprg0_val);
		if (rc != 0)
			return rc;

		rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
		if (rc != 0)
			return rc;

		if (cpu_has_feature(CPU_FTR_ARCH_300)) {
			rc = opal_slw_set_reg(pir, P9_STOP_SPR_MSR, msr_val);
			if (rc)
				return rc;

			rc = opal_slw_set_reg(pir,
					      P9_STOP_SPR_PSSCR, psscr_val);

			if (rc)
				return rc;
		}

		/* HIDs are per core registers */
		if (cpu_thread_in_core(cpu) == 0) {

			rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
			if (rc != 0)
				return rc;

			rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
			if (rc != 0)
				return rc;

			/* Only p8 needs to set extra HID regiters */
			if (!cpu_has_feature(CPU_FTR_ARCH_300)) {

				rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
				if (rc != 0)
					return rc;

				rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
				if (rc != 0)
					return rc;

				rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
				if (rc != 0)
					return rc;
			}
		}
	}

	return 0;
}

static void pnv_alloc_idle_core_states(void)
{
	int i, j;
	int nr_cores = cpu_nr_cores();
	u32 *core_idle_state;

	/*
	 * core_idle_state - The lower 8 bits track the idle state of
	 * each thread of the core.
	 *
	 * The most significant bit is the lock bit.
	 *
	 * Initially all the bits corresponding to threads_per_core
	 * are set. They are cleared when the thread enters deep idle
	 * state like sleep and winkle/stop.
	 *
	 * Initially the lock bit is cleared.  The lock bit has 2
	 * purposes:
	 * 	a. While the first thread in the core waking up from
	 * 	   idle is restoring core state, it prevents other
	 * 	   threads in the core from switching to process
	 * 	   context.
	 * 	b. While the last thread in the core is saving the
	 *	   core state, it prevents a different thread from
	 *	   waking up.
	 */
	for (i = 0; i < nr_cores; i++) {
		int first_cpu = i * threads_per_core;
		int node = cpu_to_node(first_cpu);
		size_t paca_ptr_array_size;

		core_idle_state = kmalloc_node(sizeof(u32), GFP_KERNEL, node);
		*core_idle_state = (1 << threads_per_core) - 1;
		paca_ptr_array_size = (threads_per_core *
				       sizeof(struct paca_struct *));

		for (j = 0; j < threads_per_core; j++) {
			int cpu = first_cpu + j;

			paca_ptrs[cpu]->core_idle_state_ptr = core_idle_state;
			paca_ptrs[cpu]->thread_idle_state = PNV_THREAD_RUNNING;
			paca_ptrs[cpu]->thread_mask = 1 << j;
		}
	}

	update_subcore_sibling_mask();

	if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT) {
		int rc = pnv_save_sprs_for_deep_states();

		if (likely(!rc))
			return;

		/*
		 * The stop-api is unable to restore hypervisor
		 * resources on wakeup from platform idle states which
		 * lose full context. So disable such states.
		 */
		supported_cpuidle_states &= ~OPAL_PM_LOSE_FULL_CONTEXT;
		pr_warn("cpuidle-powernv: Disabling idle states that lose full context\n");
		pr_warn("cpuidle-powernv: Idle power-savings, CPU-Hotplug affected\n");

		if (cpu_has_feature(CPU_FTR_ARCH_300) &&
		    (pnv_deepest_stop_flag & OPAL_PM_LOSE_FULL_CONTEXT)) {
			/*
			 * Use the default stop state for CPU-Hotplug
			 * if available.
			 */
			if (default_stop_found) {
				pnv_deepest_stop_psscr_val =
					pnv_default_stop_val;
				pnv_deepest_stop_psscr_mask =
					pnv_default_stop_mask;
				pr_warn("cpuidle-powernv: Offlined CPUs will stop with psscr = 0x%016llx\n",
					pnv_deepest_stop_psscr_val);
			} else { /* Fallback to snooze loop for CPU-Hotplug */
				deepest_stop_found = false;
				pr_warn("cpuidle-powernv: Offlined CPUs will busy wait\n");
			}
		}
	}
}

u32 pnv_get_supported_cpuidle_states(void)
{
	return supported_cpuidle_states;
}
EXPORT_SYMBOL_GPL(pnv_get_supported_cpuidle_states);

static void pnv_fastsleep_workaround_apply(void *info)

{
	int rc;
	int *err = info;

	rc = opal_config_cpu_idle_state(OPAL_CONFIG_IDLE_FASTSLEEP,
					OPAL_CONFIG_IDLE_APPLY);
	if (rc)
		*err = 1;
}

/*
 * Used to store fastsleep workaround state
 * 0 - Workaround applied/undone at fastsleep entry/exit path (Default)
 * 1 - Workaround applied once, never undone.
 */
static u8 fastsleep_workaround_applyonce;

static ssize_t show_fastsleep_workaround_applyonce(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%u\n", fastsleep_workaround_applyonce);
}

static ssize_t store_fastsleep_workaround_applyonce(struct device *dev,
		struct device_attribute *attr, const char *buf,
		size_t count)
{
	cpumask_t primary_thread_mask;
	int err;
	u8 val;

	if (kstrtou8(buf, 0, &val) || val != 1)
		return -EINVAL;

	if (fastsleep_workaround_applyonce == 1)
		return count;

	/*
	 * fastsleep_workaround_applyonce = 1 implies
	 * fastsleep workaround needs to be left in 'applied' state on all
	 * the cores. Do this by-
	 * 1. Patching out the call to 'undo' workaround in fastsleep exit path
	 * 2. Sending ipi to all the cores which have at least one online thread
	 * 3. Patching out the call to 'apply' workaround in fastsleep entry
	 * path
	 * There is no need to send ipi to cores which have all threads
	 * offlined, as last thread of the core entering fastsleep or deeper
	 * state would have applied workaround.
	 */
	err = patch_instruction(
		(unsigned int *)pnv_fastsleep_workaround_at_exit,
		PPC_INST_NOP);
	if (err) {
		pr_err("fastsleep_workaround_applyonce change failed while patching pnv_fastsleep_workaround_at_exit");
		goto fail;
	}

	get_online_cpus();
	primary_thread_mask = cpu_online_cores_map();
	on_each_cpu_mask(&primary_thread_mask,
				pnv_fastsleep_workaround_apply,
				&err, 1);
	put_online_cpus();
	if (err) {
		pr_err("fastsleep_workaround_applyonce change failed while running pnv_fastsleep_workaround_apply");
		goto fail;
	}

	err = patch_instruction(
		(unsigned int *)pnv_fastsleep_workaround_at_entry,
		PPC_INST_NOP);
	if (err) {
		pr_err("fastsleep_workaround_applyonce change failed while patching pnv_fastsleep_workaround_at_entry");
		goto fail;
	}

	fastsleep_workaround_applyonce = 1;

	return count;
fail:
	return -EIO;
}

static DEVICE_ATTR(fastsleep_workaround_applyonce, 0600,
			show_fastsleep_workaround_applyonce,
			store_fastsleep_workaround_applyonce);

static unsigned long __power7_idle_type(unsigned long type)
{
	unsigned long srr1;

	if (!prep_irq_for_idle_irqsoff())
		return 0;

	__ppc64_runlatch_off();
	srr1 = power7_idle_insn(type);
	__ppc64_runlatch_on();

	fini_irq_for_idle_irqsoff();

	return srr1;
}

void power7_idle_type(unsigned long type)
{
	unsigned long srr1;

	srr1 = __power7_idle_type(type);
	irq_set_pending_from_srr1(srr1);
}

void power7_idle(void)
{
	if (!powersave_nap)
		return;

	power7_idle_type(PNV_THREAD_NAP);
}

static unsigned long __power9_idle_type(unsigned long stop_psscr_val,
				      unsigned long stop_psscr_mask)
{
	unsigned long psscr;
	unsigned long srr1;

	if (!prep_irq_for_idle_irqsoff())
		return 0;

	psscr = mfspr(SPRN_PSSCR);
	psscr = (psscr & ~stop_psscr_mask) | stop_psscr_val;

	__ppc64_runlatch_off();
	srr1 = power9_idle_stop(psscr);
	__ppc64_runlatch_on();

	fini_irq_for_idle_irqsoff();

	return srr1;
}

void power9_idle_type(unsigned long stop_psscr_val,
				      unsigned long stop_psscr_mask)
{
	unsigned long srr1;

	srr1 = __power9_idle_type(stop_psscr_val, stop_psscr_mask);
	irq_set_pending_from_srr1(srr1);
}

/*
 * Used for ppc_md.power_save which needs a function with no parameters
 */
void power9_idle(void)
{
	power9_idle_type(pnv_default_stop_val, pnv_default_stop_mask);
}

#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
/*
 * This is used in working around bugs in thread reconfiguration
 * on POWER9 (at least up to Nimbus DD2.2) relating to transactional
 * memory and the way that XER[SO] is checkpointed.
 * This function forces the core into SMT4 in order by asking
 * all other threads not to stop, and sending a message to any
 * that are in a stop state.
 * Must be called with preemption disabled.
 */
void pnv_power9_force_smt4_catch(void)
{
	int cpu, cpu0, thr;
	int awake_threads = 1;		/* this thread is awake */
	int poke_threads = 0;
	int need_awake = threads_per_core;

	cpu = smp_processor_id();
	cpu0 = cpu & ~(threads_per_core - 1);
	for (thr = 0; thr < threads_per_core; ++thr) {
		if (cpu != cpu0 + thr)
			atomic_inc(&paca_ptrs[cpu0+thr]->dont_stop);
	}
	/* order setting dont_stop vs testing requested_psscr */
	mb();
	for (thr = 0; thr < threads_per_core; ++thr) {
		if (!paca_ptrs[cpu0+thr]->requested_psscr)
			++awake_threads;
		else
			poke_threads |= (1 << thr);
	}

	/* If at least 3 threads are awake, the core is in SMT4 already */
	if (awake_threads < need_awake) {
		/* We have to wake some threads; we'll use msgsnd */
		for (thr = 0; thr < threads_per_core; ++thr) {
			if (poke_threads & (1 << thr)) {
				ppc_msgsnd_sync();
				ppc_msgsnd(PPC_DBELL_MSGTYPE, 0,
					   paca_ptrs[cpu0+thr]->hw_cpu_id);
			}
		}
		/* now spin until at least 3 threads are awake */
		do {
			for (thr = 0; thr < threads_per_core; ++thr) {
				if ((poke_threads & (1 << thr)) &&
				    !paca_ptrs[cpu0+thr]->requested_psscr) {
					++awake_threads;
					poke_threads &= ~(1 << thr);
				}
			}
		} while (awake_threads < need_awake);
	}
}
EXPORT_SYMBOL_GPL(pnv_power9_force_smt4_catch);

void pnv_power9_force_smt4_release(void)
{
	int cpu, cpu0, thr;

	cpu = smp_processor_id();
	cpu0 = cpu & ~(threads_per_core - 1);

	/* clear all the dont_stop flags */
	for (thr = 0; thr < threads_per_core; ++thr) {
		if (cpu != cpu0 + thr)
			atomic_dec(&paca_ptrs[cpu0+thr]->dont_stop);
	}
}
EXPORT_SYMBOL_GPL(pnv_power9_force_smt4_release);
#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */

#ifdef CONFIG_HOTPLUG_CPU
static void pnv_program_cpu_hotplug_lpcr(unsigned int cpu, u64 lpcr_val)
{
	u64 pir = get_hard_smp_processor_id(cpu);

	mtspr(SPRN_LPCR, lpcr_val);

	/*
	 * Program the LPCR via stop-api only if the deepest stop state
	 * can lose hypervisor context.
	 */
	if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT)
		opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
}

/*
 * pnv_cpu_offline: A function that puts the CPU into the deepest
 * available platform idle state on a CPU-Offline.
 * interrupts hard disabled and no lazy irq pending.
 */
unsigned long pnv_cpu_offline(unsigned int cpu)
{
	unsigned long srr1;
	u32 idle_states = pnv_get_supported_cpuidle_states();
	u64 lpcr_val;

	/*
	 * We don't want to take decrementer interrupts while we are
	 * offline, so clear LPCR:PECE1. We keep PECE2 (and
	 * LPCR_PECE_HVEE on P9) enabled as to let IPIs in.
	 *
	 * If the CPU gets woken up by a special wakeup, ensure that
	 * the SLW engine sets LPCR with decrementer bit cleared, else
	 * the CPU will come back to the kernel due to a spurious
	 * wakeup.
	 */
	lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1;
	pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);

	__ppc64_runlatch_off();

	if (cpu_has_feature(CPU_FTR_ARCH_300) && deepest_stop_found) {
		unsigned long psscr;

		psscr = mfspr(SPRN_PSSCR);
		psscr = (psscr & ~pnv_deepest_stop_psscr_mask) |
						pnv_deepest_stop_psscr_val;
		srr1 = power9_offline_stop(psscr);

	} else if ((idle_states & OPAL_PM_WINKLE_ENABLED) &&
		   (idle_states & OPAL_PM_LOSE_FULL_CONTEXT)) {
		srr1 = power7_idle_insn(PNV_THREAD_WINKLE);
	} else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
		   (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
		srr1 = power7_idle_insn(PNV_THREAD_SLEEP);
	} else if (idle_states & OPAL_PM_NAP_ENABLED) {
		srr1 = power7_idle_insn(PNV_THREAD_NAP);
	} else {
		/* This is the fallback method. We emulate snooze */
		while (!generic_check_cpu_restart(cpu)) {
			HMT_low();
			HMT_very_low();
		}
		srr1 = 0;
		HMT_medium();
	}

	__ppc64_runlatch_on();

	/*
	 * Re-enable decrementer interrupts in LPCR.
	 *
	 * Further, we want stop states to be woken up by decrementer
	 * for non-hotplug cases. So program the LPCR via stop api as
	 * well.
	 */
	lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1;
	pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);

	return srr1;
}
#endif

/*
 * Power ISA 3.0 idle initialization.
 *
 * POWER ISA 3.0 defines a new SPR Processor stop Status and Control
 * Register (PSSCR) to control idle behavior.
 *
 * PSSCR layout:
 * ----------------------------------------------------------
 * | PLS | /// | SD | ESL | EC | PSLL | /// | TR | MTL | RL |
 * ----------------------------------------------------------
 * 0      4     41   42    43   44     48    54   56    60
 *
 * PSSCR key fields:
 *	Bits 0:3  - Power-Saving Level Status (PLS). This field indicates the
 *	lowest power-saving state the thread entered since stop instruction was
 *	last executed.
 *
 *	Bit 41 - Status Disable(SD)
 *	0 - Shows PLS entries
 *	1 - PLS entries are all 0
 *
 *	Bit 42 - Enable State Loss
 *	0 - No state is lost irrespective of other fields
 *	1 - Allows state loss
 *
 *	Bit 43 - Exit Criterion
 *	0 - Exit from power-save mode on any interrupt
 *	1 - Exit from power-save mode controlled by LPCR's PECE bits
 *
 *	Bits 44:47 - Power-Saving Level Limit
 *	This limits the power-saving level that can be entered into.
 *
 *	Bits 60:63 - Requested Level
 *	Used to specify which power-saving level must be entered on executing
 *	stop instruction
 */

int validate_psscr_val_mask(u64 *psscr_val, u64 *psscr_mask, u32 flags)
{
	int err = 0;

	/*
	 * psscr_mask == 0xf indicates an older firmware.
	 * Set remaining fields of psscr to the default values.
	 * See NOTE above definition of PSSCR_HV_DEFAULT_VAL
	 */
	if (*psscr_mask == 0xf) {
		*psscr_val = *psscr_val | PSSCR_HV_DEFAULT_VAL;
		*psscr_mask = PSSCR_HV_DEFAULT_MASK;
		return err;
	}

	/*
	 * New firmware is expected to set the psscr_val bits correctly.
	 * Validate that the following invariants are correctly maintained by
	 * the new firmware.
	 * - ESL bit value matches the EC bit value.
	 * - ESL bit is set for all the deep stop states.
	 */
	if (GET_PSSCR_ESL(*psscr_val) != GET_PSSCR_EC(*psscr_val)) {
		err = ERR_EC_ESL_MISMATCH;
	} else if ((flags & OPAL_PM_LOSE_FULL_CONTEXT) &&
		GET_PSSCR_ESL(*psscr_val) == 0) {
		err = ERR_DEEP_STATE_ESL_MISMATCH;
	}

	return err;
}

/*
 * pnv_arch300_idle_init: Initializes the default idle state, first
 *                        deep idle state and deepest idle state on
 *                        ISA 3.0 CPUs.
 *
 * @np: /ibm,opal/power-mgt device node
 * @flags: cpu-idle-state-flags array
 * @dt_idle_states: Number of idle state entries
 * Returns 0 on success
 */
static int __init pnv_power9_idle_init(void)
{
	u64 max_residency_ns = 0;
	int i;

	/*
	 * Set pnv_first_deep_stop_state, pnv_deepest_stop_psscr_{val,mask},
	 * and the pnv_default_stop_{val,mask}.
	 *
	 * pnv_first_deep_stop_state should be set to the first stop
	 * level to cause hypervisor state loss.
	 *
	 * pnv_deepest_stop_{val,mask} should be set to values corresponding to
	 * the deepest stop state.
	 *
	 * pnv_default_stop_{val,mask} should be set to values corresponding to
	 * the shallowest (OPAL_PM_STOP_INST_FAST) loss-less stop state.
	 */
	pnv_first_deep_stop_state = MAX_STOP_STATE;
	for (i = 0; i < nr_pnv_idle_states; i++) {
		int err;
		struct pnv_idle_states_t *state = &pnv_idle_states[i];
		u64 psscr_rl = state->psscr_val & PSSCR_RL_MASK;

		if ((state->flags & OPAL_PM_LOSE_FULL_CONTEXT) &&
		    pnv_first_deep_stop_state > psscr_rl)
			pnv_first_deep_stop_state = psscr_rl;

		err = validate_psscr_val_mask(&state->psscr_val,
					      &state->psscr_mask,
					      state->flags);
		if (err) {
			report_invalid_psscr_val(state->psscr_val, err);
			continue;
		}

		state->valid = true;

		if (max_residency_ns < state->residency_ns) {
			max_residency_ns = state->residency_ns;
			pnv_deepest_stop_psscr_val = state->psscr_val;
			pnv_deepest_stop_psscr_mask = state->psscr_mask;
			pnv_deepest_stop_flag = state->flags;
			deepest_stop_found = true;
		}

		if (!default_stop_found &&
		    (state->flags & OPAL_PM_STOP_INST_FAST)) {
			pnv_default_stop_val = state->psscr_val;
			pnv_default_stop_mask = state->psscr_mask;
			default_stop_found = true;
		}
	}

	if (unlikely(!default_stop_found)) {
		pr_warn("cpuidle-powernv: No suitable default stop state found. Disabling platform idle.\n");
	} else {
		ppc_md.power_save = power9_idle;
		pr_info("cpuidle-powernv: Default stop: psscr = 0x%016llx,mask=0x%016llx\n",
			pnv_default_stop_val, pnv_default_stop_mask);
	}

	if (unlikely(!deepest_stop_found)) {
		pr_warn("cpuidle-powernv: No suitable stop state for CPU-Hotplug. Offlined CPUs will busy wait");
	} else {
		pr_info("cpuidle-powernv: Deepest stop: psscr = 0x%016llx,mask=0x%016llx\n",
			pnv_deepest_stop_psscr_val,
			pnv_deepest_stop_psscr_mask);
	}

	pr_info("cpuidle-powernv: Requested Level (RL) value of first deep stop = 0x%llx\n",
		pnv_first_deep_stop_state);

	return 0;
}

/*
 * Probe device tree for supported idle states
 */
static void __init pnv_probe_idle_states(void)
{
	int i;

	if (nr_pnv_idle_states < 0) {
		pr_warn("cpuidle-powernv: no idle states found in the DT\n");
		return;
	}

	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
		if (pnv_power9_idle_init())
			return;
	}

	for (i = 0; i < nr_pnv_idle_states; i++)
		supported_cpuidle_states |= pnv_idle_states[i].flags;
}

/*
 * This function parses device-tree and populates all the information
 * into pnv_idle_states structure. It also sets up nr_pnv_idle_states
 * which is the number of cpuidle states discovered through device-tree.
 */

static int pnv_parse_cpuidle_dt(void)
{
	struct device_node *np;
	int nr_idle_states, i;
	int rc = 0;
	u32 *temp_u32;
	u64 *temp_u64;
	const char **temp_string;

	np = of_find_node_by_path("/ibm,opal/power-mgt");
	if (!np) {
		pr_warn("opal: PowerMgmt Node not found\n");
		return -ENODEV;
	}
	nr_idle_states = of_property_count_u32_elems(np,
						"ibm,cpu-idle-state-flags");

	pnv_idle_states = kcalloc(nr_idle_states, sizeof(*pnv_idle_states),
				  GFP_KERNEL);
	temp_u32 = kcalloc(nr_idle_states, sizeof(u32),  GFP_KERNEL);
	temp_u64 = kcalloc(nr_idle_states, sizeof(u64),  GFP_KERNEL);
	temp_string = kcalloc(nr_idle_states, sizeof(char *),  GFP_KERNEL);

	if (!(pnv_idle_states && temp_u32 && temp_u64 && temp_string)) {
		pr_err("Could not allocate memory for dt parsing\n");
		rc = -ENOMEM;
		goto out;
	}

	/* Read flags */
	if (of_property_read_u32_array(np, "ibm,cpu-idle-state-flags",
				       temp_u32, nr_idle_states)) {
		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-flags in DT\n");
		rc = -EINVAL;
		goto out;
	}
	for (i = 0; i < nr_idle_states; i++)
		pnv_idle_states[i].flags = temp_u32[i];

	/* Read latencies */
	if (of_property_read_u32_array(np, "ibm,cpu-idle-state-latencies-ns",
				       temp_u32, nr_idle_states)) {
		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
		rc = -EINVAL;
		goto out;
	}
	for (i = 0; i < nr_idle_states; i++)
		pnv_idle_states[i].latency_ns = temp_u32[i];

	/* Read residencies */
	if (of_property_read_u32_array(np, "ibm,cpu-idle-state-residency-ns",
				       temp_u32, nr_idle_states)) {
		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
		rc = -EINVAL;
		goto out;
	}
	for (i = 0; i < nr_idle_states; i++)
		pnv_idle_states[i].residency_ns = temp_u32[i];

	/* For power9 */
	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
		/* Read pm_crtl_val */
		if (of_property_read_u64_array(np, "ibm,cpu-idle-state-psscr",
					       temp_u64, nr_idle_states)) {
			pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-psscr in DT\n");
			rc = -EINVAL;
			goto out;
		}
		for (i = 0; i < nr_idle_states; i++)
			pnv_idle_states[i].psscr_val = temp_u64[i];

		/* Read pm_crtl_mask */
		if (of_property_read_u64_array(np, "ibm,cpu-idle-state-psscr-mask",
					       temp_u64, nr_idle_states)) {
			pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-psscr-mask in DT\n");
			rc = -EINVAL;
			goto out;
		}
		for (i = 0; i < nr_idle_states; i++)
			pnv_idle_states[i].psscr_mask = temp_u64[i];
	}

	/*
	 * power8 specific properties ibm,cpu-idle-state-pmicr-mask and
	 * ibm,cpu-idle-state-pmicr-val were never used and there is no
	 * plan to use it in near future. Hence, not parsing these properties
	 */

	if (of_property_read_string_array(np, "ibm,cpu-idle-state-names",
					  temp_string, nr_idle_states) < 0) {
		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-names in DT\n");
		rc = -EINVAL;
		goto out;
	}
	for (i = 0; i < nr_idle_states; i++)
		strlcpy(pnv_idle_states[i].name, temp_string[i],
			PNV_IDLE_NAME_LEN);
	nr_pnv_idle_states = nr_idle_states;
	rc = 0;
out:
	kfree(temp_u32);
	kfree(temp_u64);
	kfree(temp_string);
	return rc;
}

static int __init pnv_init_idle_states(void)
{
	int rc = 0;
	supported_cpuidle_states = 0;

	/* In case we error out nr_pnv_idle_states will be zero */
	nr_pnv_idle_states = 0;
	if (cpuidle_disable != IDLE_NO_OVERRIDE)
		goto out;
	rc = pnv_parse_cpuidle_dt();
	if (rc)
		return rc;
	pnv_probe_idle_states();

	if (!(supported_cpuidle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
		patch_instruction(
			(unsigned int *)pnv_fastsleep_workaround_at_entry,
			PPC_INST_NOP);
		patch_instruction(
			(unsigned int *)pnv_fastsleep_workaround_at_exit,
			PPC_INST_NOP);
	} else {
		/*
		 * OPAL_PM_SLEEP_ENABLED_ER1 is set. It indicates that
		 * workaround is needed to use fastsleep. Provide sysfs
		 * control to choose how this workaround has to be applied.
		 */
		device_create_file(cpu_subsys.dev_root,
				&dev_attr_fastsleep_workaround_applyonce);
	}

	pnv_alloc_idle_core_states();

	if (supported_cpuidle_states & OPAL_PM_NAP_ENABLED)
		ppc_md.power_save = power7_idle;

out:
	return 0;
}
machine_subsys_initcall(powernv, pnv_init_idle_states);