drivers/cpuidle/cpuidle-pseries.c - SHIFTPHONES/mainline/linux - Gitiles

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  cpuidle-pseries - idle state cpuidle driver.
  *  Adapted from drivers/idle/intel_idle.c and
  *  drivers/acpi/processor_idle.c
  *
  */

 #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 <asm/paca.h>
 #include <asm/reg.h>
 #include <asm/machdep.h>
 #include <asm/firmware.h>
 #include <asm/runlatch.h>
 #include <asm/idle.h>
 #include <asm/plpar_wrappers.h>
 #include <asm/rtas.h>

 static struct cpuidle_driver pseries_idle_driver = {
 	.name             = "pseries_idle",
 	.owner            = THIS_MODULE,
 };

 static int max_idle_state __read_mostly;
 static struct cpuidle_state *cpuidle_state_table __read_mostly;
 static u64 snooze_timeout __read_mostly;
 static bool snooze_timeout_en __read_mostly;

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

 	set_thread_flag(TIF_POLLING_NRFLAG);

 	pseries_idle_prolog();
 	local_irq_enable();
 	snooze_exit_time = get_tb() + snooze_timeout;

 	while (!need_resched()) {
 		HMT_low();
 		HMT_very_low();
 		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();
 	clear_thread_flag(TIF_POLLING_NRFLAG);

 	local_irq_disable();

 	pseries_idle_epilog();

 	return index;
 }

 static void check_and_cede_processor(void)
 {
 	/*
 	 * Ensure our interrupt state is properly tracked,
 	 * also checks if no interrupt has occurred while we
 	 * were soft-disabled
 	 */
 	if (prep_irq_for_idle()) {
 		cede_processor();
 #ifdef CONFIG_TRACE_IRQFLAGS
 		/* Ensure that H_CEDE returns with IRQs on */
 		if (WARN_ON(!(mfmsr() & MSR_EE)))
 			__hard_irq_enable();
 #endif
 	}
 }

 /*
  * XCEDE: Extended CEDE states discovered through the
  *        "ibm,get-systems-parameter" RTAS call with the token
  *        CEDE_LATENCY_TOKEN
  */

 /*
  * Section 7.3.16 System Parameters Option of PAPR version 2.8.1 has a
  * table with all the parameters to ibm,get-system-parameters.
  * CEDE_LATENCY_TOKEN corresponds to the token value for Cede Latency
  * Settings Information.
  */
 #define CEDE_LATENCY_TOKEN	45

 /*
  * If the platform supports the cede latency settings information system
  * parameter it must provide the following information in the NULL terminated
  * parameter string:
  *
  * a. The first byte is the length “N” of each cede latency setting record minus
  *    one (zero indicates a length of 1 byte).
  *
  * b. For each supported cede latency setting a cede latency setting record
  *    consisting of the first “N” bytes as per the following table.
  *
  *    -----------------------------
  *    | Field           | Field   |
  *    | Name            | Length  |
  *    -----------------------------
  *    | Cede Latency    | 1 Byte  |
  *    | Specifier Value |         |
  *    -----------------------------
  *    | Maximum wakeup  |         |
  *    | latency in      | 8 Bytes |
  *    | tb-ticks        |         |
  *    -----------------------------
  *    | Responsive to   |         |
  *    | external        | 1 Byte  |
  *    | interrupts      |         |
  *    -----------------------------
  *
  * This version has cede latency record size = 10.
  *
  * The structure xcede_latency_payload represents a) and b) with
  * xcede_latency_record representing the table in b).
  *
  * xcede_latency_parameter is what gets returned by
  * ibm,get-systems-parameter RTAS call when made with
  * CEDE_LATENCY_TOKEN.
  *
  * These structures are only used to represent the data obtained by the RTAS
  * call. The data is in big-endian.
  */
 struct xcede_latency_record {
 	u8	hint;
 	__be64	latency_ticks;
 	u8	wake_on_irqs;
 } __packed;

 // Make space for 16 records, which "should be enough".
 struct xcede_latency_payload {
 	u8     record_size;
 	struct xcede_latency_record records[16];
 } __packed;

 struct xcede_latency_parameter {
 	__be16  payload_size;
 	struct xcede_latency_payload payload;
 	u8 null_char;
 } __packed;

 static unsigned int nr_xcede_records;
 static struct xcede_latency_parameter xcede_latency_parameter __initdata;

 static int __init parse_cede_parameters(void)
 {
 	struct xcede_latency_payload *payload;
 	u32 total_xcede_records_size;
 	u8 xcede_record_size;
 	u16 payload_size;
 	int ret, i;

 	ret = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
 			NULL, CEDE_LATENCY_TOKEN, __pa(&xcede_latency_parameter),
 			sizeof(xcede_latency_parameter));
 	if (ret) {
 		pr_err("xcede: Error parsing CEDE_LATENCY_TOKEN\n");
 		return ret;
 	}

 	payload_size = be16_to_cpu(xcede_latency_parameter.payload_size);
 	payload = &xcede_latency_parameter.payload;

 	xcede_record_size = payload->record_size + 1;

 	if (xcede_record_size != sizeof(struct xcede_latency_record)) {
 		pr_err("xcede: Expected record-size %lu. Observed size %u.\n",
 		       sizeof(struct xcede_latency_record), xcede_record_size);
 		return -EINVAL;
 	}

 	pr_info("xcede: xcede_record_size = %d\n", xcede_record_size);

 	/*
 	 * Since the payload_size includes the last NULL byte and the
 	 * xcede_record_size, the remaining bytes correspond to array of all
 	 * cede_latency settings.
 	 */
 	total_xcede_records_size = payload_size - 2;
 	nr_xcede_records = total_xcede_records_size / xcede_record_size;

 	for (i = 0; i < nr_xcede_records; i++) {
 		struct xcede_latency_record *record = &payload->records[i];
 		u64 latency_ticks = be64_to_cpu(record->latency_ticks);
 		u8 wake_on_irqs = record->wake_on_irqs;
 		u8 hint = record->hint;

 		pr_info("xcede: Record %d : hint = %u, latency = 0x%llx tb ticks, Wake-on-irq = %u\n",
 			i, hint, latency_ticks, wake_on_irqs);
 	}

 	return 0;
 }

 #define NR_DEDICATED_STATES	2 /* snooze, CEDE */
 static u8 cede_latency_hint[NR_DEDICATED_STATES];

 static int dedicated_cede_loop(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv,
 				int index)
 {
 	u8 old_latency_hint;

 	pseries_idle_prolog();
 	get_lppaca()->donate_dedicated_cpu = 1;
 	old_latency_hint = get_lppaca()->cede_latency_hint;
 	get_lppaca()->cede_latency_hint = cede_latency_hint[index];

 	HMT_medium();
 	check_and_cede_processor();

 	local_irq_disable();
 	get_lppaca()->donate_dedicated_cpu = 0;
 	get_lppaca()->cede_latency_hint = old_latency_hint;

 	pseries_idle_epilog();

 	return index;
 }

 static int shared_cede_loop(struct cpuidle_device *dev,
 			struct cpuidle_driver *drv,
 			int index)
 {

 	pseries_idle_prolog();

 	/*
 	 * Yield the processor to the hypervisor.  We return if
 	 * an external interrupt occurs (which are driven prior
 	 * to returning here) or if a prod occurs from another
 	 * processor. When returning here, external interrupts
 	 * are enabled.
 	 */
 	check_and_cede_processor();

 	local_irq_disable();
 	pseries_idle_epilog();

 	return index;
 }

 /*
  * States for dedicated partition case.
  */
 static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = {
 	{ /* Snooze */
 		.name = "snooze",
 		.desc = "snooze",
 		.exit_latency = 0,
 		.target_residency = 0,
 		.enter = &snooze_loop },
 	{ /* CEDE */
 		.name = "CEDE",
 		.desc = "CEDE",
 		.exit_latency = 10,
 		.target_residency = 100,
 		.enter = &dedicated_cede_loop },
 };

 /*
  * States for shared partition case.
  */
 static struct cpuidle_state shared_states[] = {
 	{ /* Snooze */
 		.name = "snooze",
 		.desc = "snooze",
 		.exit_latency = 0,
 		.target_residency = 0,
 		.enter = &snooze_loop },
 	{ /* Shared Cede */
 		.name = "Shared Cede",
 		.desc = "Shared Cede",
 		.exit_latency = 10,
 		.target_residency = 100,
 		.enter = &shared_cede_loop },
 };

 static int pseries_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 pseries_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;
 }

 /*
  * pseries_cpuidle_driver_init()
  */
 static int pseries_cpuidle_driver_init(void)
 {
 	int idle_state;
 	struct cpuidle_driver *drv = &pseries_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 void __init fixup_cede0_latency(void)
 {
 	struct xcede_latency_payload *payload;
 	u64 min_xcede_latency_us = UINT_MAX;
 	int i;

 	if (parse_cede_parameters())
 		return;

 	pr_info("cpuidle: Skipping the %d Extended CEDE idle states\n",
 		nr_xcede_records);

 	payload = &xcede_latency_parameter.payload;

 	/*
 	 * The CEDE idle state maps to CEDE(0). While the hypervisor
 	 * does not advertise CEDE(0) exit latency values, it does
 	 * advertise the latency values of the extended CEDE states.
 	 * We use the lowest advertised exit latency value as a proxy
 	 * for the exit latency of CEDE(0).
 	 */
 	for (i = 0; i < nr_xcede_records; i++) {
 		struct xcede_latency_record *record = &payload->records[i];
 		u8 hint = record->hint;
 		u64 latency_tb = be64_to_cpu(record->latency_ticks);
 		u64 latency_us = DIV_ROUND_UP_ULL(tb_to_ns(latency_tb), NSEC_PER_USEC);

 		/*
 		 * We expect the exit latency of an extended CEDE
 		 * state to be non-zero, it to since it takes at least
 		 * a few nanoseconds to wakeup the idle CPU and
 		 * dispatch the virtual processor into the Linux
 		 * Guest.
 		 *
 		 * So we consider only non-zero value for performing
 		 * the fixup of CEDE(0) latency.
 		 */
 		if (latency_us == 0) {
 			pr_warn("cpuidle: Skipping xcede record %d [hint=%d]. Exit latency = 0us\n",
 				i, hint);
 			continue;
 		}

 		if (latency_us < min_xcede_latency_us)
 			min_xcede_latency_us = latency_us;
 	}

 	if (min_xcede_latency_us != UINT_MAX) {
 		dedicated_states[1].exit_latency = min_xcede_latency_us;
 		dedicated_states[1].target_residency = 10 * (min_xcede_latency_us);
 		pr_info("cpuidle: Fixed up CEDE exit latency to %llu us\n",
 			min_xcede_latency_us);
 	}

 }

 /*
  * pseries_idle_probe()
  * Choose state table for shared versus dedicated partition
  */
 static int __init pseries_idle_probe(void)
 {

 	if (cpuidle_disable != IDLE_NO_OVERRIDE)
 		return -ENODEV;

 	if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
 		/*
 		 * Use local_paca instead of get_lppaca() since
 		 * preemption is not disabled, and it is not required in
 		 * fact, since lppaca_ptr does not need to be the value
 		 * associated to the current CPU, it can be from any CPU.
 		 */
 		if (lppaca_shared_proc(local_paca->lppaca_ptr)) {
 			cpuidle_state_table = shared_states;
 			max_idle_state = ARRAY_SIZE(shared_states);
 		} else {
 			/*
 			 * Use firmware provided latency values
 			 * starting with POWER10 platforms. In the
 			 * case that we are running on a POWER10
 			 * platform but in an earlier compat mode, we
 			 * can still use the firmware provided values.
 			 *
 			 * However, on platforms prior to POWER10, we
 			 * cannot rely on the accuracy of the firmware
 			 * provided latency values. On such platforms,
 			 * go with the conservative default estimate
 			 * of 10us.
 			 */
 			if (cpu_has_feature(CPU_FTR_ARCH_31) || pvr_version_is(PVR_POWER10))
 				fixup_cede0_latency();
 			cpuidle_state_table = dedicated_states;
 			max_idle_state = NR_DEDICATED_STATES;
 		}
 	} else
 		return -ENODEV;

 	if (max_idle_state > 1) {
 		snooze_timeout_en = true;
 		snooze_timeout = cpuidle_state_table[1].target_residency *
 				 tb_ticks_per_usec;
 	}
 	return 0;
 }

 static int __init pseries_processor_idle_init(void)
 {
 	int retval;

 	retval = pseries_idle_probe();
 	if (retval)
 		return retval;

 	pseries_cpuidle_driver_init();
 	retval = cpuidle_register(&pseries_idle_driver, NULL);
 	if (retval) {
 		printk(KERN_DEBUG "Registration of pseries driver failed.\n");
 		return retval;
 	}

 	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 					   "cpuidle/pseries:online",
 					   pseries_cpuidle_cpu_online, NULL);
 	WARN_ON(retval < 0);
 	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
 					   "cpuidle/pseries:DEAD", NULL,
 					   pseries_cpuidle_cpu_dead);
 	WARN_ON(retval < 0);
 	printk(KERN_DEBUG "pseries_idle_driver registered\n");
 	return 0;
 }

 device_initcall(pseries_processor_idle_init);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* cpuidle-pseries - idle state cpuidle driver.
	* Adapted from drivers/idle/intel_idle.c and
	* drivers/acpi/processor_idle.c
	*
	*/

	#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 <asm/paca.h>
	#include <asm/reg.h>
	#include <asm/machdep.h>
	#include <asm/firmware.h>
	#include <asm/runlatch.h>
	#include <asm/idle.h>
	#include <asm/plpar_wrappers.h>
	#include <asm/rtas.h>

	static struct cpuidle_driver pseries_idle_driver = {
	.name = "pseries_idle",
	.owner = THIS_MODULE,
	};

	static int max_idle_state __read_mostly;
	static struct cpuidle_state *cpuidle_state_table __read_mostly;
	static u64 snooze_timeout __read_mostly;
	static bool snooze_timeout_en __read_mostly;

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

	set_thread_flag(TIF_POLLING_NRFLAG);

	pseries_idle_prolog();
	local_irq_enable();
	snooze_exit_time = get_tb() + snooze_timeout;

	while (!need_resched()) {
	HMT_low();
	HMT_very_low();
	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();
	clear_thread_flag(TIF_POLLING_NRFLAG);

	local_irq_disable();

	pseries_idle_epilog();

	return index;
	}

	static void check_and_cede_processor(void)
	{
	/*
	* Ensure our interrupt state is properly tracked,
	* also checks if no interrupt has occurred while we
	* were soft-disabled
	*/
	if (prep_irq_for_idle()) {
	cede_processor();
	#ifdef CONFIG_TRACE_IRQFLAGS
	/* Ensure that H_CEDE returns with IRQs on */
	if (WARN_ON(!(mfmsr() & MSR_EE)))
	__hard_irq_enable();
	#endif
	}
	}

	/*
	* XCEDE: Extended CEDE states discovered through the
	* "ibm,get-systems-parameter" RTAS call with the token
	* CEDE_LATENCY_TOKEN
	*/

	/*
	* Section 7.3.16 System Parameters Option of PAPR version 2.8.1 has a
	* table with all the parameters to ibm,get-system-parameters.
	* CEDE_LATENCY_TOKEN corresponds to the token value for Cede Latency
	* Settings Information.
	*/
	#define CEDE_LATENCY_TOKEN 45

	/*
	* If the platform supports the cede latency settings information system
	* parameter it must provide the following information in the NULL terminated
	* parameter string:
	*
	* a. The first byte is the length “N” of each cede latency setting record minus
	* one (zero indicates a length of 1 byte).
	*
	* b. For each supported cede latency setting a cede latency setting record
	* consisting of the first “N” bytes as per the following table.
	*
	* -----------------------------
	* \| Field \| Field \|
	* \| Name \| Length \|
	* -----------------------------
	* \| Cede Latency \| 1 Byte \|
	* \| Specifier Value \| \|
	* -----------------------------
	* \| Maximum wakeup \| \|
	* \| latency in \| 8 Bytes \|
	* \| tb-ticks \| \|
	* -----------------------------
	* \| Responsive to \| \|
	* \| external \| 1 Byte \|
	* \| interrupts \| \|
	* -----------------------------
	*
	* This version has cede latency record size = 10.
	*
	* The structure xcede_latency_payload represents a) and b) with
	* xcede_latency_record representing the table in b).
	*
	* xcede_latency_parameter is what gets returned by
	* ibm,get-systems-parameter RTAS call when made with
	* CEDE_LATENCY_TOKEN.
	*
	* These structures are only used to represent the data obtained by the RTAS
	* call. The data is in big-endian.
	*/
	struct xcede_latency_record {
	u8 hint;
	__be64 latency_ticks;
	u8 wake_on_irqs;
	} __packed;

	// Make space for 16 records, which "should be enough".
	struct xcede_latency_payload {
	u8 record_size;
	struct xcede_latency_record records[16];
	} __packed;

	struct xcede_latency_parameter {
	__be16 payload_size;
	struct xcede_latency_payload payload;
	u8 null_char;
	} __packed;

	static unsigned int nr_xcede_records;
	static struct xcede_latency_parameter xcede_latency_parameter __initdata;

	static int __init parse_cede_parameters(void)
	{
	struct xcede_latency_payload *payload;
	u32 total_xcede_records_size;
	u8 xcede_record_size;
	u16 payload_size;
	int ret, i;

	ret = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
	NULL, CEDE_LATENCY_TOKEN, __pa(&xcede_latency_parameter),
	sizeof(xcede_latency_parameter));
	if (ret) {
	pr_err("xcede: Error parsing CEDE_LATENCY_TOKEN\n");
	return ret;
	}

	payload_size = be16_to_cpu(xcede_latency_parameter.payload_size);
	payload = &xcede_latency_parameter.payload;

	xcede_record_size = payload->record_size + 1;

	if (xcede_record_size != sizeof(struct xcede_latency_record)) {
	pr_err("xcede: Expected record-size %lu. Observed size %u.\n",
	sizeof(struct xcede_latency_record), xcede_record_size);
	return -EINVAL;
	}

	pr_info("xcede: xcede_record_size = %d\n", xcede_record_size);

	/*
	* Since the payload_size includes the last NULL byte and the
	* xcede_record_size, the remaining bytes correspond to array of all
	* cede_latency settings.
	*/
	total_xcede_records_size = payload_size - 2;
	nr_xcede_records = total_xcede_records_size / xcede_record_size;

	for (i = 0; i < nr_xcede_records; i++) {
	struct xcede_latency_record *record = &payload->records[i];
	u64 latency_ticks = be64_to_cpu(record->latency_ticks);
	u8 wake_on_irqs = record->wake_on_irqs;
	u8 hint = record->hint;

	pr_info("xcede: Record %d : hint = %u, latency = 0x%llx tb ticks, Wake-on-irq = %u\n",
	i, hint, latency_ticks, wake_on_irqs);
	}

	return 0;
	}

	#define NR_DEDICATED_STATES 2 /* snooze, CEDE */
	static u8 cede_latency_hint[NR_DEDICATED_STATES];

	static int dedicated_cede_loop(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int index)
	{
	u8 old_latency_hint;

	pseries_idle_prolog();
	get_lppaca()->donate_dedicated_cpu = 1;
	old_latency_hint = get_lppaca()->cede_latency_hint;
	get_lppaca()->cede_latency_hint = cede_latency_hint[index];

	HMT_medium();
	check_and_cede_processor();

	local_irq_disable();
	get_lppaca()->donate_dedicated_cpu = 0;
	get_lppaca()->cede_latency_hint = old_latency_hint;

	pseries_idle_epilog();

	return index;
	}

	static int shared_cede_loop(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int index)
	{

	pseries_idle_prolog();

	/*
	* Yield the processor to the hypervisor. We return if
	* an external interrupt occurs (which are driven prior
	* to returning here) or if a prod occurs from another
	* processor. When returning here, external interrupts
	* are enabled.
	*/
	check_and_cede_processor();

	local_irq_disable();
	pseries_idle_epilog();

	return index;
	}

	/*
	* States for dedicated partition case.
	*/
	static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = {
	{ /* Snooze */
	.name = "snooze",
	.desc = "snooze",
	.exit_latency = 0,
	.target_residency = 0,
	.enter = &snooze_loop },
	{ /* CEDE */
	.name = "CEDE",
	.desc = "CEDE",
	.exit_latency = 10,
	.target_residency = 100,
	.enter = &dedicated_cede_loop },
	};

	/*
	* States for shared partition case.
	*/
	static struct cpuidle_state shared_states[] = {
	{ /* Snooze */
	.name = "snooze",
	.desc = "snooze",
	.exit_latency = 0,
	.target_residency = 0,
	.enter = &snooze_loop },
	{ /* Shared Cede */
	.name = "Shared Cede",
	.desc = "Shared Cede",
	.exit_latency = 10,
	.target_residency = 100,
	.enter = &shared_cede_loop },
	};

	static int pseries_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 pseries_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;
	}

	/*
	* pseries_cpuidle_driver_init()
	*/
	static int pseries_cpuidle_driver_init(void)
	{
	int idle_state;
	struct cpuidle_driver *drv = &pseries_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 void __init fixup_cede0_latency(void)
	{
	struct xcede_latency_payload *payload;
	u64 min_xcede_latency_us = UINT_MAX;
	int i;

	if (parse_cede_parameters())
	return;

	pr_info("cpuidle: Skipping the %d Extended CEDE idle states\n",
	nr_xcede_records);

	payload = &xcede_latency_parameter.payload;

	/*
	* The CEDE idle state maps to CEDE(0). While the hypervisor
	* does not advertise CEDE(0) exit latency values, it does
	* advertise the latency values of the extended CEDE states.
	* We use the lowest advertised exit latency value as a proxy
	* for the exit latency of CEDE(0).
	*/
	for (i = 0; i < nr_xcede_records; i++) {
	struct xcede_latency_record *record = &payload->records[i];
	u8 hint = record->hint;
	u64 latency_tb = be64_to_cpu(record->latency_ticks);
	u64 latency_us = DIV_ROUND_UP_ULL(tb_to_ns(latency_tb), NSEC_PER_USEC);

	/*
	* We expect the exit latency of an extended CEDE
	* state to be non-zero, it to since it takes at least
	* a few nanoseconds to wakeup the idle CPU and
	* dispatch the virtual processor into the Linux
	* Guest.
	*
	* So we consider only non-zero value for performing
	* the fixup of CEDE(0) latency.
	*/
	if (latency_us == 0) {
	pr_warn("cpuidle: Skipping xcede record %d [hint=%d]. Exit latency = 0us\n",
	i, hint);
	continue;
	}

	if (latency_us < min_xcede_latency_us)
	min_xcede_latency_us = latency_us;
	}

	if (min_xcede_latency_us != UINT_MAX) {
	dedicated_states[1].exit_latency = min_xcede_latency_us;
	dedicated_states[1].target_residency = 10 * (min_xcede_latency_us);
	pr_info("cpuidle: Fixed up CEDE exit latency to %llu us\n",
	min_xcede_latency_us);
	}

	}

	/*
	* pseries_idle_probe()
	* Choose state table for shared versus dedicated partition
	*/
	static int __init pseries_idle_probe(void)
	{

	if (cpuidle_disable != IDLE_NO_OVERRIDE)
	return -ENODEV;

	if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
	/*
	* Use local_paca instead of get_lppaca() since
	* preemption is not disabled, and it is not required in
	* fact, since lppaca_ptr does not need to be the value
	* associated to the current CPU, it can be from any CPU.
	*/
	if (lppaca_shared_proc(local_paca->lppaca_ptr)) {
	cpuidle_state_table = shared_states;
	max_idle_state = ARRAY_SIZE(shared_states);
	} else {
	/*
	* Use firmware provided latency values
	* starting with POWER10 platforms. In the
	* case that we are running on a POWER10
	* platform but in an earlier compat mode, we
	* can still use the firmware provided values.
	*
	* However, on platforms prior to POWER10, we
	* cannot rely on the accuracy of the firmware
	* provided latency values. On such platforms,
	* go with the conservative default estimate
	* of 10us.
	*/
	if (cpu_has_feature(CPU_FTR_ARCH_31) \|\| pvr_version_is(PVR_POWER10))
	fixup_cede0_latency();
	cpuidle_state_table = dedicated_states;
	max_idle_state = NR_DEDICATED_STATES;
	}
	} else
	return -ENODEV;

	if (max_idle_state > 1) {
	snooze_timeout_en = true;
	snooze_timeout = cpuidle_state_table[1].target_residency *
	tb_ticks_per_usec;
	}
	return 0;
	}

	static int __init pseries_processor_idle_init(void)
	{
	int retval;

	retval = pseries_idle_probe();
	if (retval)
	return retval;

	pseries_cpuidle_driver_init();
	retval = cpuidle_register(&pseries_idle_driver, NULL);
	if (retval) {
	printk(KERN_DEBUG "Registration of pseries driver failed.\n");
	return retval;
	}

	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
	"cpuidle/pseries:online",
	pseries_cpuidle_cpu_online, NULL);
	WARN_ON(retval < 0);
	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
	"cpuidle/pseries:DEAD", NULL,
	pseries_cpuidle_cpu_dead);
	WARN_ON(retval < 0);
	printk(KERN_DEBUG "pseries_idle_driver registered\n");
	return 0;
	}

	device_initcall(pseries_processor_idle_init);