powerpc/powernv: Add poweroff (EPOW, DPO) events support for PowerNV platform

This patch adds support for FSP EPOW (Early Power Off Warning) and
DPO (Delayed Power Off) events support for PowerNV platform.  EPOW events
are generated by SPCN/FSP due to various critical system conditions that
need system shutdown.  Few examples of these conditions are high ambient
temperature or system running on UPS power with low UPS battery. DPO event
is generated in response to admin initiated system shutdown request.
	This patch enables host kernel on PowerNV platform to handle OPAL
notifications for these events and initiate system poweroff. Since EPOW
notifications are sent in advance of impending shutdown event and thus this
patch also adds functionality to wait for EPOW condition to return to
normal.  If EPOW condition doesn't return to normal in estimated time it
proceeds with graceful system shutdown. System admin can also add host
userspace scripts to perform any specific actions like graceful guest
shutdown upon system poweroff.

Signed-off-by: Vipin K Parashar <vipin@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/opal-api.h                |  30 ++
 arch/powerpc/include/asm/opal.h                    |   3 +-
 arch/powerpc/platforms/powernv/Makefile            |   1 +
 .../platforms/powernv/opal-poweroff-events.c       | 358 +++++++++++++++++++++
 arch/powerpc/platforms/powernv/opal-wrappers.S     |   1 +
 5 files changed, 392 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/platforms/powernv/opal-poweroff-events.c

On 04/30/2015 11:37 AM, Vipin K Parashar wrote:
> diff --git a/arch/powerpc/platforms/powernv/opal-poweroff-events.c b/arch/powerpc/platforms/powernv/opal-poweroff-events.c
> new file mode 100644
> index 0000000..9b169e2
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/opal-poweroff-events.c
> @@ -0,0 +1,358 @@
> +/*
> + * PowerNV poweroff events support
> + *
> + * 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.
> + */
> +
> +#define pr_fmt(fmt)	"POWEROFF_EVENT: "    fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/spinlock.h>
> +#include <linux/timer.h>
> +#include <linux/reboot.h>
> +#include <asm/opal.h>
> +#include <asm/machdep.h>
> +
> +/* System EPOW status */
> +u32 epow_status[OPAL_MAX_EPOW_CLASSES];
> +int num_epow_classes;

static

> +
> +/* EPOW event timer and corresponding locks */
> +static struct timer_list epow_timer;
> +static DEFINE_SPINLOCK(epow_timer_spinlock);
> +
> +/* EPOW, DPO event status values */
> +#define	DPO_DETECTED	1
> +#define	EPOW_DETECTED	1
> +
> +/* EPOW events supported */
> +#define EPOW_POWER_UPS          0
> +#define EPOW_POWER_UPS_LOW      1
> +#define EPOW_TEMP_HIGH_AMB      2
> +#define EPOW_TEMP_CRIT_AMB      3
> +#define EPOW_TEMP_HIGH_INT      4
> +#define EPOW_TEMP_CRIT_INT      5
> +#define MAX_EPOW_EVENTS		6
> +
> +/* EPOW events description */
> +static const char * const epow_events_map[] = {
> +	[EPOW_POWER_UPS]	= "UPS",
> +	[EPOW_POWER_UPS_LOW]	= "UPS-low",
> +	[EPOW_TEMP_HIGH_AMB]	= "high-ambient-temp",
> +	[EPOW_TEMP_CRIT_AMB]	= "crit-ambient-temp",
> +	[EPOW_TEMP_HIGH_INT]	= "high-internal-temp",
> +	[EPOW_TEMP_CRIT_INT]	= "crit-internal-temp",
> +};
> +
> +/* EPOW events timeout values */
> +static int epow_timeout[MAX_EPOW_EVENTS];
> +
> +/*
> + * TODO: Export various event timeout values via device tree.
> + *  Zero timeout value for any event suggests that it needs
> + *  immediate shutdown.
> + */
> +#define TIMEOUT_EPOW_POWER_UPS		450
> +#define TIMEOUT_EPOW_TEMP_HIGH_AMB	450
> +
> +/*
> + * Get various EPOW event timeouts.
> + * TODO: For now hardcoding timeout values but they need to be
> + * obtained via firmware device-tree.
> + */
> +void get_epow_timeouts(void)

static ?

> +{
> +	epow_timeout[EPOW_POWER_UPS] = TIMEOUT_EPOW_POWER_UPS;
> +	epow_timeout[EPOW_TEMP_HIGH_AMB] = TIMEOUT_EPOW_TEMP_HIGH_AMB;

What about the timeout values for other cases ? don't see assigned
anywhere but used in the process_epow() function..

> +}
> +
> +/* EPOW poweroff function. */
> +static void epow_poweroff(unsigned long event)
> +{
> +	pr_info("Powering off system due to %s EPOW event\n",
> +				epow_events_map[event]);
> +	orderly_poweroff(true);
> +}
> +
> +/* Start EPOW poweroff timer */
> +static void start_epow_timer(unsigned long event, int32_t timeout)

'event' is of type 'int' which you are passing..

> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&epow_timer_spinlock, flags);
> +	/* Check for already running epow poweroff timer */
> +	if (timer_pending(&epow_timer)) {
> +		/* Timer for same event */
> +		if (epow_timer.data == event) {
> +			spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +			return;
> +		}
> +
> +		/* Timer with early poweroff timeout */
> +		if (epow_timer.expires < (jiffies + timeout * HZ)) {

Should it also return for the equal condition ?

if (epow_timer.expires <= (jiffies + timeout * HZ))

> +			event = epow_timer.data;
> +			spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +			pr_info("Poweroff already scheduled for %s EPOW event "
> +					"with earlier timeout.\n",
> +					epow_events_map[event]);
> +			return;
> +		}
> +	}
> +
> +	/* Start a new timer/modify existing timer with new timeout value */
> +	epow_timer.data = event;
> +	mod_timer(&epow_timer, jiffies + timeout  * HZ);
> +	spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +	pr_info("Scheduled system poweroff due to %s EPOW event "
> +			"after %d seconds\n", epow_events_map[event], timeout);
> +}
> +
> +/* Stop poweroff timer */
> +static void stop_epow_timer(void)
> +{
> +	int rc;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&epow_timer_spinlock, flags);
> +	rc = del_timer(&epow_timer);
> +	spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +
> +	if (rc)
> +		pr_info("Poweroff timer deactivated\n");
> +}
> +
> +/* Get DPO status */
> +static int get_dpo_status(int32_t *dpo_timeout)
> +{
> +	int rc;
> +	__be32 opal_dpo_timeout;
> +
> +	rc = opal_get_dpo_status(&opal_dpo_timeout);
> +	if (rc == OPAL_WRONG_STATE) {
> +		*dpo_timeout = 0;
> +		return 0;
> +	}
> +
> +	*dpo_timeout = be32_to_cpu(opal_dpo_timeout);
> +	return DPO_DETECTED;
> +}
> +
> +/* Process DPO event */
> +void process_dpo(void)

static function ?

> +{
> +	pr_info("Powering off system due to poweroff request.\n");
> +	orderly_poweroff(true);
> +}
> +
> +/* Get EPOW status */
> +static int get_epow_status(void)
> +{
> +	int i;
> +	bool epow_detected = false;
> +
> +	__be32 opal_epow_status[OPAL_MAX_EPOW_CLASSES];
> +	__be32 opal_epow_classes;
> +
> +	opal_epow_classes = cpu_to_be32(OPAL_MAX_EPOW_CLASSES);
> +	for (i = 0; i < OPAL_MAX_EPOW_CLASSES; i++)
> +		opal_epow_status[i] = cpu_to_be32(0);
> +
> +	/* Get EPOW events information from OPAL */
> +	opal_get_epow_status(opal_epow_status, &opal_epow_classes);
> +
> +	/* Copy EPOW status */
> +	memset(epow_status, 0, sizeof(epow_status[0] * OPAL_MAX_EPOW_CLASSES));
> +	num_epow_classes = be32_to_cpu(opal_epow_classes);
> +	for (i = 0; i < num_epow_classes; i++) {
> +		epow_status[i] = be32_to_cpu(opal_epow_status[i]);
> +		if (epow_status[i])
> +			epow_detected = true;
> +	}
> +
> +	pr_info("EPOW classes supported OPAL = %d, Host = %d "
> +			"EPOW Status = 0x%x, 0x%x, 0x%x\n",
> +			num_epow_classes, OPAL_MAX_EPOW_CLASSES,
> +			epow_status[0], epow_status[1], epow_status[2]);
> +
> +	if (epow_detected)
> +		return EPOW_DETECTED;
> +
> +	return 0;
> +}
> +
> +/* Process EPOW information */
> +void process_epow(void)
> +{
> +	int i, timeout = 0, event = -1;
> +	bool epow_normal = false;
> +
> +	/* Check for EPOW return to normal state */
> +	for (i = 0; i < OPAL_MAX_EPOW_CLASSES; i++) {

s/OPAL_MAX_EPOW_CLASSES/num_epow_classes

> +		if (epow_status[i])
> +			break;
> +	}
> +
> +	if (i == OPAL_MAX_EPOW_CLASSES)
> +		epow_normal = true;
> +
> +	/* Cancel any pending shutdown timer due to EPOW normal state.*/
> +	if (epow_normal) {
> +		stop_epow_timer();
> +		return;
> +	}
> +
> +	/* Determine EPOW events and poweroff timeouts */
> +	if (epow_status[OPAL_EPOW_POWER] & OPAL_EPOW_POWER_UPS) {
> +		pr_info("EPOW due to system running on UPS power\n");
> +		event = EPOW_POWER_UPS;
> +		timeout = epow_timeout[EPOW_POWER_UPS];
> +	}
> +
> +	if (epow_status[OPAL_EPOW_POWER] & OPAL_EPOW_POWER_UPS_LOW) {
> +		pr_info("EPOW due to system running on UPS power "
> +				"with low battery\n");
> +		event = EPOW_POWER_UPS_LOW;
> +		timeout = epow_timeout[EPOW_POWER_UPS_LOW];
> +	}
> +
> +	if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_HIGH_AMB) {
> +		pr_info("EPOW due to high ambient temperature\n");
> +		event = EPOW_TEMP_HIGH_AMB;
> +		timeout = epow_timeout[EPOW_TEMP_HIGH_AMB];
> +	}
> +
> +	if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_CRIT_AMB) {
> +		pr_info("EPOW due to critical ambient temperature\n");
> +		event = EPOW_TEMP_CRIT_AMB;
> +		timeout = epow_timeout[EPOW_TEMP_CRIT_AMB];
> +	}
> +
> +	if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_HIGH_INT) {
> +		pr_info("EPOW due to high internal temperature\n");
> +		event = EPOW_TEMP_HIGH_INT;
> +		timeout = epow_timeout[EPOW_TEMP_HIGH_INT];
> +	}
> +
> +	if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_CRIT_INT) {
> +		pr_info("EPOW due to critical internal temperature\n");
> +		event = EPOW_TEMP_CRIT_INT;
> +		timeout = epow_timeout[EPOW_TEMP_CRIT_INT];
> +	}

'event' & 'timeout' values are getting updated after each check, I guess
for multiple types of epow cases.. Can it be changed to if-elseif-if 
construct..
and check based on the criticality ...?

> +
> +	if (event == -1) {
> +		pr_err("Unknown EPOW event\n");
> +		return;
> +	}
> +
> +	/* Start EPOW poweroff timer */
> +	start_epow_timer(event, timeout);
> +}
> +
> +/* Check for any existing EPOW, DPO events and process them, if existing */
> +static void process_existing_poweroff_events(void)
> +{
> +	int rc;
> +	int32_t dpo_timeout;
> +
> +	/* Check for any existing DPO event */
> +	rc = get_dpo_status(&dpo_timeout);
> +	if (rc == DPO_DETECTED) {
> +		pr_info("Existing DPO event detected\n");
> +		process_dpo();
> +		return;
> +	 } else
> +		pr_info("No existing DPO event detected\n");
> +
> +	/* Check for any existing EPOW event */
> +	rc = get_epow_status();
> +	if (rc == EPOW_DETECTED) {
> +		pr_info("Existing EPOW event detected.\n");
> +		process_epow();
> +	} else
> +		pr_info("No existing EPOW event detected\n");
> +
> +}
> +
> +/* Platform EPOW message received */
> +static int opal_epow_event(struct notifier_block *nb,
> +			unsigned long msg_type, void *msg)
> +{
> +	pr_info("EPOW event received\n");
> +
> +	/* Get EPOW event details */
> +	get_epow_status();
> +
> +	/* Process EPOW event information */
> +	process_epow();
> +
> +	return 0;
> +}
> +
> +
> +/* Platform DPO message received */
> +static int opal_dpo_event(struct notifier_block *nb,
> +				unsigned long msg_type, void *msg)
> +{
> +	pr_info("DPO event received.\n");
> +	process_dpo();
> +
> +	return 0;
> +}
> +
> +
> +/* OPAL EPOW event notifier block */
> +static struct notifier_block opal_epow_nb = {
> +	.notifier_call  = opal_epow_event,
> +	.next           = NULL,
> +	.priority       = 0,
> +};
> +
> +/* OPAL DPO event notifier block */
> +static struct notifier_block opal_dpo_nb = {
> +	.notifier_call  = opal_dpo_event,
> +	.next           = NULL,
> +	.priority       = 0,
> +};
> +
> +/* Poweroff events init */
> +static int opal_poweroff_events_init(void)

Use '__init' macro for the initialization function.

> +{
> +	int ret;
> +
> +	/* Initialize poweroff timer */
> +	init_timer(&epow_timer);
> +	epow_timer.function = epow_poweroff;
> +
> +	/* Get EPOW event timeout values */
> +	get_epow_timeouts();
> +
> +	/* Check for any existing EPOW or DPO events. */
> +	process_existing_poweroff_events();
> +
> +	/* Register EPOW event notifier */
> +	ret = opal_message_notifier_register(OPAL_MSG_EPOW, &opal_epow_nb);
> +	if (ret) {
> +		pr_err("EPOW event notifier registration failed\n");
> +		return ret;
> +	}
> +
> +	/* Register DPO event notifier */
> +	ret = opal_message_notifier_register(OPAL_MSG_DPO, &opal_dpo_nb);
> +	if (ret) {
> +		pr_err("DPO event notifier registration failed\n");
> +		opal_notifier_unregister(&opal_epow_nb);

opal_message_notifier_unregister() instead.
plus delete the timer too.

Regards,
Neelesh.

> +		return ret;
> +	}
> +
> +
> +	pr_info("OPAL poweroff events support initialized\n");
> +
> +	return 0;
> +}
> +
> +machine_subsys_initcall(powernv, opal_poweroff_events_init);
> diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
> index a7ade94..5d3c8e3 100644
> --- a/arch/powerpc/platforms/powernv/opal-wrappers.S
> +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
> @@ -249,6 +249,7 @@ OPAL_CALL(opal_pci_reinit,			OPAL_PCI_REINIT);
>   OPAL_CALL(opal_pci_mask_pe_error,		OPAL_PCI_MASK_PE_ERROR);
>   OPAL_CALL(opal_set_slot_led_status,		OPAL_SET_SLOT_LED_STATUS);
>   OPAL_CALL(opal_get_epow_status,			OPAL_GET_EPOW_STATUS);
> +OPAL_CALL(opal_get_dpo_status,			OPAL_GET_DPO_STATUS);
>   OPAL_CALL(opal_set_system_attention_led,	OPAL_SET_SYSTEM_ATTENTION_LED);
>   OPAL_CALL(opal_pci_next_error,			OPAL_PCI_NEXT_ERROR);
>   OPAL_CALL(opal_pci_poll,			OPAL_PCI_POLL);

> On 30-Apr-2015, at 11:37, Vipin K Parashar <vipin@linux.vnet.ibm.com> wrote:
> 
> This patch adds support for FSP EPOW (Early Power Off Warning) and
> DPO (Delayed Power Off) events support for PowerNV platform.  EPOW events
> are generated by SPCN/FSP due to various critical system conditions that
> need system shutdown.  Few examples of these conditions are high ambient
> temperature or system running on UPS power with low UPS battery. DPO event
> is generated in response to admin initiated system shutdown request.
>    This patch enables host kernel on PowerNV platform to handle OPAL
> notifications for these events and initiate system poweroff. Since EPOW
> notifications are sent in advance of impending shutdown event and thus this
> patch also adds functionality to wait for EPOW condition to return to
> normal.  If EPOW condition doesn't return to normal in estimated time it
> proceeds with graceful system shutdown. System admin can also add host
> userspace scripts to perform any specific actions like graceful guest
> shutdown upon system poweroff.
> 
> Signed-off-by: Vipin K Parashar <vipin@linux.vnet.ibm.com>
> ---
> arch/powerpc/include/asm/opal-api.h                |  30 ++
> arch/powerpc/include/asm/opal.h                    |   3 +-
> arch/powerpc/platforms/powernv/Makefile            |   1 +
> .../platforms/powernv/opal-poweroff-events.c       | 358 +++++++++++++++++++++
> arch/powerpc/platforms/powernv/opal-wrappers.S     |   1 +
> 5 files changed, 392 insertions(+), 1 deletion(-)
> create mode 100644 arch/powerpc/platforms/powernv/opal-poweroff-events.c
> 
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index 0321a90..03b3cef 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -730,6 +730,36 @@ struct opal_i2c_request {
>    __be64 buffer_ra;        /* Buffer real address */
> };
> 
> +/*
> + * EPOW status sharing (OPAL and the host)
> + *
> + * The host will pass on OPAL, a buffer of length OPAL_EPOW_MAX_CLASSES
> + * to fetch system wide EPOW status. Each element in the returned buffer
> + * will contain bitwise EPOW status for each EPOW sub class.
> + */
> +
> +/* EPOW types */
> +enum OpalEpow {
> +    OPAL_EPOW_POWER         = 0,    /* Power EPOW */
> +    OPAL_EPOW_TEMP          = 1,    /* Temperature EPOW */
> +    OPAL_EPOW_COOLING       = 2,    /* Cooling EPOW */
> +    OPAL_MAX_EPOW_CLASSES   = 3,    /* Max EPOW categories */
> +};
> +
> +/* Power EPOW events */
> +enum OpalEpowPower {
> +    OPAL_EPOW_POWER_UPS     = 0x1, /* System on UPS power */
> +    OPAL_EPOW_POWER_UPS_LOW = 0x2, /* System on UPS power with low battery*/
> +};
> +
> +/* Temperature EPOW events */
> +enum OpalEpowTemp {
> +    OPAL_EPOW_TEMP_HIGH_AMB = 0x1, /* High ambient temperature */
> +    OPAL_EPOW_TEMP_CRIT_AMB = 0x2, /* Critical ambient temperature */
> +    OPAL_EPOW_TEMP_HIGH_INT = 0x4, /* High internal temperature */
> +    OPAL_EPOW_TEMP_CRIT_INT = 0x8, /* Critical internal temperature */
> +};
> +
> #endif /* __ASSEMBLY__ */
> 
> #endif /* __OPAL_API_H */
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index 042af1a..0777864 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -141,7 +141,6 @@ int64_t opal_pci_fence_phb(uint64_t phb_id);
> int64_t opal_pci_reinit(uint64_t phb_id, uint64_t reinit_scope, uint64_t data);
> int64_t opal_pci_mask_pe_error(uint64_t phb_id, uint16_t pe_number, uint8_t error_type, uint8_t mask_action);
> int64_t opal_set_slot_led_status(uint64_t phb_id, uint64_t slot_id, uint8_t led_type, uint8_t led_action);
> -int64_t opal_get_epow_status(__be64 *status);
> int64_t opal_set_system_attention_led(uint8_t led_action);
> int64_t opal_pci_next_error(uint64_t phb_id, __be64 *first_frozen_pe,
>                __be16 *pci_error_type, __be16 *severity);
> @@ -200,6 +199,8 @@ int64_t opal_flash_write(uint64_t id, uint64_t offset, uint64_t buf,
>        uint64_t size, uint64_t token);
> int64_t opal_flash_erase(uint64_t id, uint64_t offset, uint64_t size,
>        uint64_t token);
> +int32_t opal_get_epow_status(__be32 *status, __be32 *num_classes);
> +int32_t opal_get_dpo_status(__be32 *timeout);
> 
> /* Internal functions */
> extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
> index 33e44f3..b817bdb 100644
> --- a/arch/powerpc/platforms/powernv/Makefile
> +++ b/arch/powerpc/platforms/powernv/Makefile
> @@ -2,6 +2,7 @@ obj-y            += setup.o opal-wrappers.o opal.o opal-async.o
> obj-y            += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
> obj-y            += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o
> obj-y            += opal-msglog.o opal-hmi.o opal-power.o
> +obj-y            += opal-poweroff-events.o
> 
> obj-$(CONFIG_SMP)    += smp.o subcore.o subcore-asm.o
> obj-$(CONFIG_PCI)    += pci.o pci-p5ioc2.o pci-ioda.o
> diff --git a/arch/powerpc/platforms/powernv/opal-poweroff-events.c b/arch/powerpc/platforms/powernv/opal-poweroff-events.c
> new file mode 100644
> index 0000000..9b169e2
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/opal-poweroff-events.c
> @@ -0,0 +1,358 @@
Instead of creating a new file can you merge this functionality with existing code in opal-power.c. It seems to be doing work similar to what you are doing in this code.
> +/*
> + * PowerNV poweroff events support
> + *
> + * 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.
> + */
> +
> +#define pr_fmt(fmt)    "POWEROFF_EVENT: "    fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/spinlock.h>
> +#include <linux/timer.h>
> +#include <linux/reboot.h>
> +#include <asm/opal.h>
> +#include <asm/machdep.h>
> +
> +/* System EPOW status */
> +u32 epow_status[OPAL_MAX_EPOW_CLASSES];
> +int num_epow_classes;
> +
> +/* EPOW event timer and corresponding locks */
> +static struct timer_list epow_timer;
> +static DEFINE_SPINLOCK(epow_timer_spinlock);
> +
> +/* EPOW, DPO event status values */
> +#define    DPO_DETECTED    1
> +#define    EPOW_DETECTED    1
Instead of macros for this can you simply return a bool from corresponding functions.
> +
> +/* EPOW events supported */
> +#define EPOW_POWER_UPS          0
> +#define EPOW_POWER_UPS_LOW      1
> +#define EPOW_TEMP_HIGH_AMB      2
> +#define EPOW_TEMP_CRIT_AMB      3
> +#define EPOW_TEMP_HIGH_INT      4
> +#define EPOW_TEMP_CRIT_INT      5
> +#define MAX_EPOW_EVENTS        6
> +
> +/* EPOW events description */
> +static const char * const epow_events_map[] = {
> +    [EPOW_POWER_UPS]    = "UPS",
> +    [EPOW_POWER_UPS_LOW]    = "UPS-low",
> +    [EPOW_TEMP_HIGH_AMB]    = "high-ambient-temp",
> +    [EPOW_TEMP_CRIT_AMB]    = "crit-ambient-temp",
> +    [EPOW_TEMP_HIGH_INT]    = "high-internal-temp",
> +    [EPOW_TEMP_CRIT_INT]    = "crit-internal-temp",
> +};
> +
> +/* EPOW events timeout values */
> +static int epow_timeout[MAX_EPOW_EVENTS];
> +
> +/*
> + * TODO: Export various event timeout values via device tree.
> + *  Zero timeout value for any event suggests that it needs
> + *  immediate shutdown.
> + */
> +#define TIMEOUT_EPOW_POWER_UPS        450
> +#define TIMEOUT_EPOW_TEMP_HIGH_AMB    450
> +
> +/*
> + * Get various EPOW event timeouts.
> + * TODO: For now hardcoding timeout values but they need to be
> + * obtained via firmware device-tree.
> + */
> +void get_epow_timeouts(void)
> +{
> +    epow_timeout[EPOW_POWER_UPS] = TIMEOUT_EPOW_POWER_UPS;
> +    epow_timeout[EPOW_TEMP_HIGH_AMB] = TIMEOUT_EPOW_TEMP_HIGH_AMB;
> +}
> +
Instead of having a separate function function for initialising the array you can use array initialisers.
> +/* EPOW poweroff function. */
> +static void epow_poweroff(unsigned long event)
> +{
> +    pr_info("Powering off system due to %s EPOW event\n",
> +                epow_events_map[event]);
> +    orderly_poweroff(true);
> +}
> +
> +/* Start EPOW poweroff timer */
> +static void start_epow_timer(unsigned long event, int32_t timeout)
> +{
> +    unsigned long flags;
> +
> +    spin_lock_irqsave(&epow_timer_spinlock, flags);
> +    /* Check for already running epow poweroff timer */
> +    if (timer_pending(&epow_timer)) {
> +        /* Timer for same event */
> +        if (epow_timer.data == event) {
> +            spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +            return;
> +        }
> +
> +        /* Timer with early poweroff timeout */
> +        if (epow_timer.expires < (jiffies + timeout * HZ)) {
> +            event = epow_timer.data;
> +            spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +            pr_info("Poweroff already scheduled for %s EPOW event "
> +                    "with earlier timeout.\n",
> +                    epow_events_map[event]);
> +            return;
> +        }
> +    }
> +
> +    /* Start a new timer/modify existing timer with new timeout value */
> +    epow_timer.data = event;
> +    mod_timer(&epow_timer, jiffies + timeout  * HZ);
> +    spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +    pr_info("Scheduled system poweroff due to %s EPOW event "
> +            "after %d seconds\n", epow_events_map[event], timeout);
> +}
> +
> +/* Stop poweroff timer */
> +static void stop_epow_timer(void)
> +{
> +    int rc;
> +    unsigned long flags;
> +
> +    spin_lock_irqsave(&epow_timer_spinlock, flags);
> +    rc = del_timer(&epow_timer);
> +    spin_unlock_irqrestore(&epow_timer_spinlock, flags);
> +
> +    if (rc)
> +        pr_info("Poweroff timer deactivated\n");
> +}
> +
> +/* Get DPO status */
> +static int get_dpo_status(int32_t *dpo_timeout)
> +{
> +    int rc;
> +    __be32 opal_dpo_timeout;
> +
> +    rc = opal_get_dpo_status(&opal_dpo_timeout);
> +    if (rc == OPAL_WRONG_STATE) {
> +        *dpo_timeout = 0;
> +        return 0;
> +    }
> +
> +    *dpo_timeout = be32_to_cpu(opal_dpo_timeout);
> +    return DPO_DETECTED;
> +}
> +
> +/* Process DPO event */
> +void process_dpo(void)
> +{
> +    pr_info("Powering off system due to poweroff request.\n");
> +    orderly_poweroff(true);
> +}
Function too small and can be combined with function opal_dpo_event.
> +
> +/* Get EPOW status */
> +static int get_epow_status(void)
> +{
> +    int i;
> +    bool epow_detected = false;
> +
> +    __be32 opal_epow_status[OPAL_MAX_EPOW_CLASSES];
> +    __be32 opal_epow_classes;
> +
> +    opal_epow_classes = cpu_to_be32(OPAL_MAX_EPOW_CLASSES);
> +    for (i = 0; i < OPAL_MAX_EPOW_CLASSES; i++)
> +        opal_epow_status[i] = cpu_to_be32(0);
0 is represented same in be or le. So instead use static initialiser for the array.
> +
> +    /* Get EPOW events information from OPAL */
> +    opal_get_epow_status(opal_epow_status, &opal_epow_classes);
Since you get the number of classes copied to the array back from opal, you may not need to initialise it to zero in the loop above.
> +
> +    /* Copy EPOW status */
> +     memset(epow_status, 0, sizeof(epow_status[0] * OPAL_MAX_EPOW_CLASSES);
Simple memset(epow_status, 0, sizeof(epow_status)) should have the same effect
> +    num_epos_classes = be32_to_cpu(opal_epow_classes);
> +    for (i = 0; i < num_epow_classes; i++) {
> +        epow_status[i] = be32_to_cpu(opal_epow_status[i]);
> +        if (epow_status[i])
> +            epow_detected = true;
> +    }
> +
> +    pr_info("EPOW classes supported OPAL = %d, Host = %d "
> +            "EPOW Status = 0x%x, 0x%x, 0x%x\n",
> +            num_epow_classes, OPAL_MAX_EPOW_CLASSES,
> +            epow_status[0], epow_status[1], epow_status[2]);
> +
> +    if (epow_detected)
> +        return EPOW_DETECTED;
> +
> +    return 0;
> +}
> +
> +/* Process EPOW information */
> +void process_epow(void)
> +{
> +    int i, timeout = 0, event = -1;
> +    bool epow_normal = false;
> +
> +    /* Check for EPOW return to normal state */
> +    for (i = 0; i < OPAL_MAX_EPOW_CLASSES; i++) {
> +        if (epow_status[i])
> +            break;
> +    }
This is the same check you do in func get_epow_status. Instead refactor the code to do this check only once.
> +
> +    if (i == OPAL_MAX_EPOW_CLASSES)
> +        epow_normal = true;
> +
> +    /* Cancel any pending shutdown timer due to EPOW normal state.*/
> +    if (epow_normal) {
> +        stop_epow_timer(); 
> +        return;
> +    }
Can merge the two if conditions above to eliminate variable epow_normal.
> +
> +    /* Determine EPOW events and poweroff timeouts */
> +    if (epow_status[OPAL_EPOW_POWER] & OPAL_EPOW_POWER_UPS) {
> +        pr_info("EPOW due to system running on UPS power\n");
> +        event = EPOW_POWER_UPS;
> +        timeout = epow_timeout[EPOW_POWER_UPS];
> +    }
> +
> +    if (epow_status[OPAL_EPOW_POWER] & OPAL_EPOW_POWER_UPS_LOW) {
> +        pr_info("EPOW due to system running on UPS power "
> +                "with low battery\n
> +        event = EPOW_POWER_UPS_LOW;
> +        timeout = epow_timeout[EPOW_POWER_UPS_LOW];
> +    }
> +
> +    if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_HIGH_AMB) {
> +        pr_info("EPOW due to high ambient temperature\n");
> +        event = EPOW_TEMP_HIGH_AMB;
> +        timeout = epow_timeout[EPOW_TEMP_HIGH_AMB];
> +    }
> +
> +    if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_CRIT_AMB) {
> +        pr_info("EPOW due to critical ambient temperature\n");
> +        event = EPOW_TEMP_CRIT_AMB;
> +        timeout = epow_timeout[EPOW_TEMP_CRIT_AMB];
> +    }
> +
> +    if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_HIGH_INT) {
> +        pr_info("EPOW due to high internal temperature\n");
> +        event = EPOW_TEMP_HIGH_INT;
> +        timeout = epow_timeout[EPOW_TEMP_HIGH_INT];
> +    }
> +
> +    if (epow_status[OPAL_EPOW_TEMP] & OPAL_EPOW_TEMP_CRIT_INT) {
> +        pr_info("EPOW due to critical internal temperature\n");
> +        event = EPOW_TEMP_CRIT_INT;
> +        timeout = epow_timeout[EPOW_TEMP_CRIT_INT];
> +    }
> +
> +    if (event == -1) {
> +        pr_err("Unknown EPOW event\n");
> +        return;
> +    }
> +
> +    /* Start EPOW poweroff timer */
> +    start_epow_timer(event, timeout);
> +}
> +
> +/* Check for any existing EPOW, DPO events and process them, if existing */
> +static void process_existing_poweroff_events(void)
> +{
> +    int rc;
> +    int32_t dpo_timeout;
> +
> +    /* Check for any existing DPO event */
> +    rc = get_dpo_status(&dpo_timeout);
> +    if (rc == DPO_DETECTED) {
> +        pr_info("Existing DPO event detected\n");
> +        process_dpo();
> +        return;
> +     } else
> +        pr_info("No existing DPO event detected\n");
> +
> +    /* Check for any existing EPOW event */
> +    rc = get_epow_status();
> +    if (rc == EPOW_DETECTED) {
> +        pr_info("Existing EPOW event detected.\n");
> +        process_epow();
> +    } else
> +        pr_info("No existing EPOW event detected\n");
> +
> +}
> +
> +/* Platform EPOW message received */
> +static int opal_epow_event(struct notifier_block *nb,
> +            unsigned long msg_type, void *msg)
> +{
> +    pr_info("EPOW event received\n");
> +
> +    /* Get EPOW event details */
> +    get_epow_status();
> +
> +    /* Process EPOW event information */
> +    process_epow();
> +
> +    return 0;
> +}
> +
> +
> +/* Platform DPO message received */
> +static int opal_dpo_event(struct notifier_block *nb,
> +                unsigned long msg_type, void *msg)
> +{
> +    pr_info("DPO event received.\n");
> +    process_dpo();
> +
> +    return 0;
> +}
> +
> +
> +/* OPAL EPOW event notifier block */
> +static struct notifier_block opal_epow_nb = {
> +    .notifier_call  = opal_epow_event,
> +    .next           = NULL,
> +    .priority       = 0,
> +};
> +
> +/* OPAL DPO event notifier block */
> +static struct notifier_block opal_dpo_nb = {
> +    .notifier_call  = opal_dpo_event,
> +    .next           = NULL,
> +    .priority       = 0,
> +};
> +
> +/* Poweroff events init */
> +static int opal_poweroff_events_init(void)
> +{
> +    int ret;
> +
> +    /* Initialize poweroff timer */
> +    init_timer(&epow_timer);
> +    epow_timer.function = epow_poweroff;
> +
> +    /* Get EPOW event timeout values */
> +    get_epow_timeouts();
> +
> +    /* Check for any existing EPOW or DPO events. */
> +    process_existing_poweroff_events();
> +
> +    /* Register EPOW event notifier */
> +    ret = opal_message_notifier_register(OPAL_MSG_EPOW, &opal_epow_nb);
> +    if (ret) {
> +        pr_err("EPOW event notifier registration failed\n");
> +        return ret;
> +    }
Timing issue. You may miss some events that occur between process existing power off event and registering message notifies. Instead first register your notifier  and then process any existing  events.
> +
> +    /* Register DPO event notifier */
> +    ret = opal_message_notifier_register(OPAL_MSG_DPO, &opal_dpo_nb);
> +    if (ret) {
> +        pr_err("DPO event notifier registration failed\n");
> +        opal_notifier_unregister(&opal_epow_nb);
> +        return ret;
> +    }
> +
> +
> +    pr_info("OPAL poweroff events support initialized\n");
> +
> +    return 0;
> +}
> +
> +machine_subsys_initcall(powernv, opal_poweroff_events_init);
> diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
> index a7ade94..5d3c8e3 100644
> --- a/arch/powerpc/platforms/powernv/opal-wrappers.S
> +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
> @@ -249,6 +249,7 @@ OPAL_CALL(opal_pci_reinit,            OPAL_PCI_REINIT);
> OPAL_CALL(opal_pci_mask_pe_error,        OPAL_PCI_MASK_PE_ERROR);
> OPAL_CALL(opal_set_slot_led_status,        OPAL_SET_SLOT_LED_STATUS);
> OPAL_CALL(opal_get_epow_status,            OPAL_GET_EPOW_STATUS);
> +OPAL_CALL(opal_get_dpo_status,            OPAL_GET_DPO_STATUS);
> OPAL_CALL(opal_set_system_attention_led,    OPAL_SET_SYSTEM_ATTENTION_LED);
> OPAL_CALL(opal_pci_next_error,            OPAL_PCI_NEXT_ERROR);
> OPAL_CALL(opal_pci_poll,            OPAL_PCI_POLL);
> -- 
> 1.9.3
> 
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