[v3,1/5] rtc: OMAP: Add system pm_power_off to rtc driver

From: Colin Foe-Parker <colin.foeparker@logicpd.com>

Add system power off control to rtc driver which is the in-charge
of controlling the BeagleBone system power. The power_off routine
can be hooked up to "pm_power_off" system call.

System power off sequence:-
* Set PMIC STATUS_OFF when PMIC_POWER_EN is pulled low
* Enable PMIC_POWER_EN in rtc module
* Set rtc ALARM2 time
* Enable ALARM2 interrupt

Added while (1); after the above steps to make sure that no other
process acquire cpu. Otherwise we might see an unexpected behaviour
because we are shutting down all the power rails of SoC except RTC.

Signed-off-by: Colin Foe-Parker <colin.foeparker@logicpd.com>
[anilkumar@ti.com: move poweroff additions to rtc driver]
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
---
 Documentation/devicetree/bindings/rtc/rtc-omap.txt |    5 ++
 drivers/rtc/rtc-omap.c                             |   81 +++++++++++++++++++-
 2 files changed, 85 insertions(+), 1 deletion(-)

+Andrew Morton

On Tue, Nov 20, 2012 at 15:18:43, AnilKumar, Chimata wrote:
> From: Colin Foe-Parker <colin.foeparker@logicpd.com>
> 
> Add system power off control to rtc driver which is the in-charge
> of controlling the BeagleBone system power. The power_off routine
> can be hooked up to "pm_power_off" system call.
> 
> System power off sequence:-
> * Set PMIC STATUS_OFF when PMIC_POWER_EN is pulled low
> * Enable PMIC_POWER_EN in rtc module
> * Set rtc ALARM2 time
> * Enable ALARM2 interrupt
> 
> Added while (1); after the above steps to make sure that no other
> process acquire cpu. Otherwise we might see an unexpected behaviour
> because we are shutting down all the power rails of SoC except RTC.

Hi All,

ACK from reviewers will help this patch get in.

Andrew,

Could you please pull this patch?

Thanks
AnilKumar

> Signed-off-by: Colin Foe-Parker <colin.foeparker@logicpd.com>
> [anilkumar@ti.com: move poweroff additions to rtc driver]
> Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
> ---
>  Documentation/devicetree/bindings/rtc/rtc-omap.txt |    5 ++
>  drivers/rtc/rtc-omap.c                             |   81 +++++++++++++++++++-
>  2 files changed, 85 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/rtc/rtc-omap.txt b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> index b47aa41..8d9f4f9 100644
> --- a/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> +++ b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> @@ -6,6 +6,10 @@ Required properties:
>  - interrupts: rtc timer, alarm interrupts in order
>  - interrupt-parent: phandle for the interrupt controller
>  
> +Optional properties:
> +- ti,system-power-controller: Telling whether or not rtc is controlling
> +  the system power.
> +
>  Example:
>  
>  rtc@1c23000 {
> @@ -14,4 +18,5 @@ rtc@1c23000 {
>  	interrupts = <19
>  		      19>;
>  	interrupt-parent = <&intc>;
> +	ti,system-power-controller;
>  };
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 6009714..c31f93a 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -72,6 +72,14 @@
>  #define OMAP_RTC_KICK0_REG		0x6c
>  #define OMAP_RTC_KICK1_REG		0x70
>  
> +#define OMAP_RTC_ALARM2_SECONDS_REG	0x80
> +#define OMAP_RTC_ALARM2_MINUTES_REG	0x84
> +#define OMAP_RTC_ALARM2_HOURS_REG	0x88
> +#define OMAP_RTC_ALARM2_DAYS_REG	0x8c
> +#define OMAP_RTC_ALARM2_MONTHS_REG	0x90
> +#define OMAP_RTC_ALARM2_YEARS_REG	0x94
> +#define OMAP_RTC_PMIC_REG		0x98
> +
>  /* OMAP_RTC_CTRL_REG bit fields: */
>  #define OMAP_RTC_CTRL_SPLIT		(1<<7)
>  #define OMAP_RTC_CTRL_DISABLE		(1<<6)
> @@ -93,15 +101,21 @@
>  #define OMAP_RTC_STATUS_BUSY            (1<<0)
>  
>  /* OMAP_RTC_INTERRUPTS_REG bit fields: */
> +#define OMAP_RTC_INTERRUPTS_IT_ALARM2   (1<<4)
>  #define OMAP_RTC_INTERRUPTS_IT_ALARM    (1<<3)
>  #define OMAP_RTC_INTERRUPTS_IT_TIMER    (1<<2)
>  
> +/* OMAP_RTC_PMIC_REG bit fields: */
> +#define OMAP_RTC_PMIC_POWER_EN_EN       (1<<16)
> +
>  /* OMAP_RTC_KICKER values */
>  #define	KICK0_VALUE			0x83e70b13
>  #define	KICK1_VALUE			0x95a4f1e0
>  
>  #define	OMAP_RTC_HAS_KICKER		0x1
>  
> +#define SHUTDOWN_TIME_SEC		2
> +
>  static void __iomem	*rtc_base;
>  
>  #define rtc_read(addr)		readb(rtc_base + (addr))
> @@ -290,6 +304,63 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
>  	return 0;
>  }
>  
> +/*
> + * rtc_power_off: Set the pmic power off sequence. The RTC generates
> + * pmic_pwr_enable control, which can be used to control an external
> + * PMIC.
> + */
> +static void rtc_power_off(void)
> +{
> +	u32 val;
> +	struct rtc_time tm;
> +	spinlock_t lock;
> +	unsigned long flags, time;
> +
> +	spin_lock_init(&lock);
> +
> +	/* Set PMIC power enable */
> +	val = readl(rtc_base + OMAP_RTC_PMIC_REG);
> +	writel(val | OMAP_RTC_PMIC_POWER_EN_EN, rtc_base + OMAP_RTC_PMIC_REG);
> +
> +	/* Read rtc time */
> +	omap_rtc_read_time(NULL, &tm);
> +
> +	/* Convert Gregorian date to seconds since 01-01-1970 00:00:00 */
> +	rtc_tm_to_time(&tm, &time);
> +
> +	/* Add shutdown time to the current value */
> +	time += SHUTDOWN_TIME_SEC;
> +
> +	/* Convert seconds since 01-01-1970 00:00:00 to Gregorian date */
> +	rtc_time_to_tm(time, &tm);
> +
> +	if (tm2bcd(&tm) < 0)
> +		return;
> +
> +	pr_info("System will go to power_off state in approx. %d secs\n",
> +			SHUTDOWN_TIME_SEC);
> +
> +	/*
> +	 * pmic_pwr_enable is controlled by means of ALARM2 event. So here
> +	 * programming alarm2 expiry time and enabling alarm2 interrupt
> +	 */
> +	rtc_write(tm.tm_sec, OMAP_RTC_ALARM2_SECONDS_REG);
> +	rtc_write(tm.tm_min, OMAP_RTC_ALARM2_MINUTES_REG);
> +	rtc_write(tm.tm_hour, OMAP_RTC_ALARM2_HOURS_REG);
> +	rtc_write(tm.tm_mday, OMAP_RTC_ALARM2_DAYS_REG);
> +	rtc_write(tm.tm_mon, OMAP_RTC_ALARM2_MONTHS_REG);
> +	rtc_write(tm.tm_year, OMAP_RTC_ALARM2_YEARS_REG);
> +
> +	/* Enable alarm2 interrupt */
> +	val = readl(rtc_base + OMAP_RTC_INTERRUPTS_REG);
> +	writel(val | OMAP_RTC_INTERRUPTS_IT_ALARM2,
> +				rtc_base + OMAP_RTC_INTERRUPTS_REG);
> +
> +	/* Do not allow to execute any other task */
> +	spin_lock_irqsave(&lock, flags);
> +	while (1);
> +}
> +
>  static struct rtc_class_ops omap_rtc_ops = {
>  	.read_time	= omap_rtc_read_time,
>  	.set_time	= omap_rtc_set_time,
> @@ -327,12 +398,16 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
>  	struct resource		*res, *mem;
>  	struct rtc_device	*rtc;
>  	u8			reg, new_ctrl;
> +	bool			pm_off = false;
>  	const struct platform_device_id *id_entry;
>  	const struct of_device_id *of_id;
>  
>  	of_id = of_match_device(omap_rtc_of_match, &pdev->dev);
> -	if (of_id)
> +	if (of_id) {
>  		pdev->id_entry = of_id->data;
> +		pm_off = of_property_read_bool(pdev->dev.of_node,
> +					"ti,system-power-controller");
> +	}
>  
>  	omap_rtc_timer = platform_get_irq(pdev, 0);
>  	if (omap_rtc_timer <= 0) {
> @@ -385,6 +460,10 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, rtc);
>  	dev_set_drvdata(&rtc->dev, mem);
>  
> +	/* RTC power off */
> +	if (pm_off && !pm_power_off)
> +		pm_power_off = rtc_power_off;
> +
>  	/* clear pending irqs, and set 1/second periodic,
>  	 * which we'll use instead of update irqs
>  	 */
> -- 
> 1.7.9.5
> 
>

On Thu, Nov 22, 2012 at 11:17:02, AnilKumar, Chimata wrote:
> +Andrew Morton
> 
> On Tue, Nov 20, 2012 at 15:18:43, AnilKumar, Chimata wrote:
> > From: Colin Foe-Parker <colin.foeparker@logicpd.com>
> > 
> > Add system power off control to rtc driver which is the in-charge
> > of controlling the BeagleBone system power. The power_off routine
> > can be hooked up to "pm_power_off" system call.
> > 
> > System power off sequence:-
> > * Set PMIC STATUS_OFF when PMIC_POWER_EN is pulled low
> > * Enable PMIC_POWER_EN in rtc module
> > * Set rtc ALARM2 time
> > * Enable ALARM2 interrupt
> > 
> > Added while (1); after the above steps to make sure that no other
> > process acquire cpu. Otherwise we might see an unexpected behaviour
> > because we are shutting down all the power rails of SoC except RTC.
> 

Reviewed-by: Vaibhav Bedia <vaibhav.bedia@ti.com>

On Tue, 20 Nov 2012 15:18:43 +0530
AnilKumar Ch <anilkumar@ti.com> wrote:

> From: Colin Foe-Parker <colin.foeparker@logicpd.com>
> 
> Add system power off control to rtc driver which is the in-charge
> of controlling the BeagleBone system power. The power_off routine
> can be hooked up to "pm_power_off" system call.
> 
> System power off sequence:-
> * Set PMIC STATUS_OFF when PMIC_POWER_EN is pulled low
> * Enable PMIC_POWER_EN in rtc module
> * Set rtc ALARM2 time
> * Enable ALARM2 interrupt
> 
> Added while (1); after the above steps to make sure that no other
> process acquire cpu. Otherwise we might see an unexpected behaviour
> because we are shutting down all the power rails of SoC except RTC.
> 
> Signed-off-by: Colin Foe-Parker <colin.foeparker@logicpd.com>
> [anilkumar@ti.com: move poweroff additions to rtc driver]
> Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
>
> ...
>
> +/*
> + * rtc_power_off: Set the pmic power off sequence. The RTC generates
> + * pmic_pwr_enable control, which can be used to control an external
> + * PMIC.
> + */
> +static void rtc_power_off(void)
> +{
> +	u32 val;
> +	struct rtc_time tm;
> +	spinlock_t lock;

What on earth?

> +	unsigned long flags, time;
> +
> +	spin_lock_init(&lock);
> +
> +	/* Set PMIC power enable */
> +	val = readl(rtc_base + OMAP_RTC_PMIC_REG);
> +	writel(val | OMAP_RTC_PMIC_POWER_EN_EN, rtc_base + OMAP_RTC_PMIC_REG);
> +
> +	/* Read rtc time */
> +	omap_rtc_read_time(NULL, &tm);
> +
> +	/* Convert Gregorian date to seconds since 01-01-1970 00:00:00 */
> +	rtc_tm_to_time(&tm, &time);
> +
> +	/* Add shutdown time to the current value */
> +	time += SHUTDOWN_TIME_SEC;
> +
> +	/* Convert seconds since 01-01-1970 00:00:00 to Gregorian date */
> +	rtc_time_to_tm(time, &tm);
> +
> +	if (tm2bcd(&tm) < 0)
> +		return;
> +
> +	pr_info("System will go to power_off state in approx. %d secs\n",
> +			SHUTDOWN_TIME_SEC);
> +
> +	/*
> +	 * pmic_pwr_enable is controlled by means of ALARM2 event. So here
> +	 * programming alarm2 expiry time and enabling alarm2 interrupt
> +	 */
> +	rtc_write(tm.tm_sec, OMAP_RTC_ALARM2_SECONDS_REG);
> +	rtc_write(tm.tm_min, OMAP_RTC_ALARM2_MINUTES_REG);
> +	rtc_write(tm.tm_hour, OMAP_RTC_ALARM2_HOURS_REG);
> +	rtc_write(tm.tm_mday, OMAP_RTC_ALARM2_DAYS_REG);
> +	rtc_write(tm.tm_mon, OMAP_RTC_ALARM2_MONTHS_REG);
> +	rtc_write(tm.tm_year, OMAP_RTC_ALARM2_YEARS_REG);
> +
> +	/* Enable alarm2 interrupt */
> +	val = readl(rtc_base + OMAP_RTC_INTERRUPTS_REG);
> +	writel(val | OMAP_RTC_INTERRUPTS_IT_ALARM2,
> +				rtc_base + OMAP_RTC_INTERRUPTS_REG);
> +
> +	/* Do not allow to execute any other task */
> +	spin_lock_irqsave(&lock, flags);
> +	while (1);

I suspect this doesn't do what you want it to do.

Firstly, please provide adequate code comments here so that code
readers do not also need to be mind readers.

If you want to stop this CPU dead in its tracks (why?) then

	local_irq_disable();
	while (1)
		;		/* Note correct code layout */

will do it.  But it means that the NMI watchdog (if present) will come
along and whack the machine in the head a few seconds later.  And this
does nothing to stop other CPUs.

But not being a mind reader, I'm really at a loss to suggest what
should be done here.  

> +}
>
> ...
>

On Tue, Nov 27, 2012 at 03:42:39PM -0800, Andrew Morton wrote:
> > +	/* Do not allow to execute any other task */
> > +	spin_lock_irqsave(&lock, flags);
> > +	while (1);
> 
> I suspect this doesn't do what you want it to do.
> 
> Firstly, please provide adequate code comments here so that code
> readers do not also need to be mind readers.
> 
> If you want to stop this CPU dead in its tracks (why?) then
> 
> 	local_irq_disable();
> 	while (1)
> 		;		/* Note correct code layout */
> 
> will do it.  But it means that the NMI watchdog (if present) will come
> along and whack the machine in the head a few seconds later.  And this
> does nothing to stop other CPUs.
> 
> But not being a mind reader, I'm really at a loss to suggest what
> should be done here.  

It's hooking into the pm_power_off hook, which is called from kernel/sys.c
via arch code.  We will have already stopped all other CPUs at this point.

Why there's that while (1) there I don't know; when pm_power_off is not
hooked, we don't do anything like that - and what will happen in that
case is we'll return all the way back to sys_reboot(), which will call
do_exit(0) on us.

I don't see a problem with that, and I don't see why we need to spin
(without any power saving too) waiting for some event.  If we've called
sys_reboot with LINUX_REBOOT_CMD_POWER_OFF, we'd better have already
killed most of userspace off by that time anyway.

On Wed, Nov 28, 2012 at 16:42:26, Russell King - ARM Linux wrote:
> On Tue, Nov 27, 2012 at 03:42:39PM -0800, Andrew Morton wrote:
> > > +	/* Do not allow to execute any other task */
> > > +	spin_lock_irqsave(&lock, flags);
> > > +	while (1);
> > 
> > I suspect this doesn't do what you want it to do.
> > 
> > Firstly, please provide adequate code comments here so that code
> > readers do not also need to be mind readers.
> > 
> > If you want to stop this CPU dead in its tracks (why?) then
> > 
> > 	local_irq_disable();
> > 	while (1)
> > 		;		/* Note correct code layout */
> > 
> > will do it.  But it means that the NMI watchdog (if present) will come
> > along and whack the machine in the head a few seconds later.  And this
> > does nothing to stop other CPUs.
> > 
> > But not being a mind reader, I'm really at a loss to suggest what
> > should be done here.  

Here intention is to disable all interrupts between rtc power_off request
till system actually went to power off mode, max 2 seconds based on when
the AM335x RTC alarm2 expires. The idea was that since the system is
going to shutdown, it is better to not process any more interrupts.

> It's hooking into the pm_power_off hook, which is called from kernel/sys.c
> via arch code.  We will have already stopped all other CPUs at this point.
> 
> Why there's that while (1) there I don't know; when pm_power_off is not
> hooked, we don't do anything like that - and what will happen in that
> case is we'll return all the way back to sys_reboot(), which will call
> do_exit(0) on us.

When testing with v3.7-rc7, I saw the following BUG() triggered when I did
not use a while(1). Logs below.

Before calling do_exit(0), there is a reboot_mutex lock that is taken in
reboot syscall. do_exit() function is , checking for any locks held by the
processor and if yes then it is printing a BUG_ON from print_held_locks_bug() function along with the locks held information.
Even though the BUG triggers, the system is going to power off because
The hardware has been triggered.

==== (log)
[root@arago /]# poweroff
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system poweroff
[   32.125900] Disabling non-boot CPUs ...
[   32.130155] Power down.
[   32.132741] System will go to power_off state in approx. 2 secs
[   32.139994]
[   32.141575] =====================================
[   32.146564] [ BUG: lock held at task exit time! ]
[   32.151522] 3.7.0-rc7-00015-g3f8bbe0 #32 Not tainted
[   32.156721] -------------------------------------
[   32.161676] init/622 is exiting with locks still held!
[   32.167085] 1 lock held by init/622:
[   32.170831]  #0:  (reboot_mutex){+.+...}, at: [<c0056fb8>] sys_reboot+0xf4/0x1e8
[   32.178679]
[   32.178679] stack backtrace:
[   32.183305] [<c001af24>] (unwind_backtrace+0x0/0xf0) from [<c0046978>] (do_exit+0x488/0x7e8)
[   32.192183] [<c0046978>] (do_exit+0x488/0x7e8) from [<c0056fc4>] (sys_reboot+0x100/0x1e8)
[   32.200797] [<c0056fc4>] (sys_reboot+0x100/0x1e8) from [<c0013320>] (ret_fast_syscall+0x0/0x3c)
=====

It is not clear to me where reboot_mutex should have been unlocked before
debug_check_no_locks_held() is called in do_exit()?

Note: In latest linux-next tip I am *not* seeing this error. I have not
bisected yet to see what fixed this. Since with latest linux-next I am
not seeing an issue, I will remove spinlock and the while(1). Hope that
will make the patch more acceptable.

> I don't see a problem with that, and I don't see why we need to spin
> (without any power saving too) waiting for some event.  If we've called
> sys_reboot with LINUX_REBOOT_CMD_POWER_OFF, we'd better have already
> killed most of userspace off by that time anyway.
> 

I did a search of various power-off implementations in *arch/arm*.

Those that use a while(1):
=========================
arch/arm/mach-at91/board-gsia18s.c
arch/arm/mach-at91/setup.c doesn't
arch/arm/mach-cns3xxx/cns3420vb.c
arch/arm/mach-iop32x/glantank.c
arch/arm/mach-iop32x/iq31244.c
arch/arm/mach-iop32x/n2100.c local_irq_disable() and then a while(1)
arch/arm/mach-kirkwood/board-lsxl.c

arch/arm/mach-highbank/highbank.c does while(1) cpu_do_idle()

Those that don't have a while(1):
================================
arch/arm/mach-imx/mach-mx31moboard.c
arch/arm/mach-iop32x/em7210.c

Doesn't have a while(1) but setting a gpio so presumably kills the system immediately:
===========
arch/arm/mach-ixp4xx/dsmg600-setup.c  
arch/arm/mach-ixp4xx/nas100d-setup.c
arch/arm/mach-ixp4xx/nslu2-setup.c
arch/arm/mach-kirkwood/board-dnskw.c
arch/arm/mach-kirkwood/board-ib62x0.c
arch/arm/mach-kirkwood/board-dnskw.c
arch/arm/mach-kirkwood/board-ib62x0.c
arch/arm/mach-kirkwood/d2net_v2-setup.c
arch/arm/mach-kirkwood/netspace_v2-setup.c
arch/arm/mach-kirkwood/netxbig_v2-setup.c
arch/arm/mach-kirkwood/t5325-setup.c
arch/arm/mach-orion5x/dns323-setup.c

arch/arm/mach-vexpress/v2m.c take a spinlock, not sure when it will shut down

arch/arm/mach-kirkwood/board-ts219.c sends a character to PIC and potentially returns...
arch/arm/mach-kirkwood/ts219-setup.c

So it seems there is a plethora of variations of how this is implemented
(probably driven also by hardware differences). Since what I mentioned
above works for me (in linux-next), I will go ahead and submit at v4.
Let me know if there are objections.

Thanks
AnilKumar

On Tue, 20 Nov 2012 15:18:43 +0530, AnilKumar Ch <anilkumar@ti.com> wrote:
> From: Colin Foe-Parker <colin.foeparker@logicpd.com>
> 
> Add system power off control to rtc driver which is the in-charge
> of controlling the BeagleBone system power. The power_off routine
> can be hooked up to "pm_power_off" system call.
> 
> System power off sequence:-
> * Set PMIC STATUS_OFF when PMIC_POWER_EN is pulled low
> * Enable PMIC_POWER_EN in rtc module
> * Set rtc ALARM2 time
> * Enable ALARM2 interrupt
> 
> Added while (1); after the above steps to make sure that no other
> process acquire cpu. Otherwise we might see an unexpected behaviour
> because we are shutting down all the power rails of SoC except RTC.
> 
> Signed-off-by: Colin Foe-Parker <colin.foeparker@logicpd.com>
> [anilkumar@ti.com: move poweroff additions to rtc driver]
> Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
> ---
>  Documentation/devicetree/bindings/rtc/rtc-omap.txt |    5 ++
>  drivers/rtc/rtc-omap.c                             |   81 +++++++++++++++++++-
>  2 files changed, 85 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/rtc/rtc-omap.txt b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> index b47aa41..8d9f4f9 100644
> --- a/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> +++ b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> @@ -6,6 +6,10 @@ Required properties:
>  - interrupts: rtc timer, alarm interrupts in order
>  - interrupt-parent: phandle for the interrupt controller
>  
> +Optional properties:
> +- ti,system-power-controller: Telling whether or not rtc is controlling
> +  the system power.
> +

Acked-by: Grant Likely <grant.likely@secretlab.ca>

>  Example:
>  
>  rtc@1c23000 {
> @@ -14,4 +18,5 @@ rtc@1c23000 {
>  	interrupts = <19
>  		      19>;
>  	interrupt-parent = <&intc>;
> +	ti,system-power-controller;
>  };
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 6009714..c31f93a 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -72,6 +72,14 @@
>  #define OMAP_RTC_KICK0_REG		0x6c
>  #define OMAP_RTC_KICK1_REG		0x70
>  
> +#define OMAP_RTC_ALARM2_SECONDS_REG	0x80
> +#define OMAP_RTC_ALARM2_MINUTES_REG	0x84
> +#define OMAP_RTC_ALARM2_HOURS_REG	0x88
> +#define OMAP_RTC_ALARM2_DAYS_REG	0x8c
> +#define OMAP_RTC_ALARM2_MONTHS_REG	0x90
> +#define OMAP_RTC_ALARM2_YEARS_REG	0x94
> +#define OMAP_RTC_PMIC_REG		0x98
> +
>  /* OMAP_RTC_CTRL_REG bit fields: */
>  #define OMAP_RTC_CTRL_SPLIT		(1<<7)
>  #define OMAP_RTC_CTRL_DISABLE		(1<<6)
> @@ -93,15 +101,21 @@
>  #define OMAP_RTC_STATUS_BUSY            (1<<0)
>  
>  /* OMAP_RTC_INTERRUPTS_REG bit fields: */
> +#define OMAP_RTC_INTERRUPTS_IT_ALARM2   (1<<4)
>  #define OMAP_RTC_INTERRUPTS_IT_ALARM    (1<<3)
>  #define OMAP_RTC_INTERRUPTS_IT_TIMER    (1<<2)
>  
> +/* OMAP_RTC_PMIC_REG bit fields: */
> +#define OMAP_RTC_PMIC_POWER_EN_EN       (1<<16)
> +
>  /* OMAP_RTC_KICKER values */
>  #define	KICK0_VALUE			0x83e70b13
>  #define	KICK1_VALUE			0x95a4f1e0
>  
>  #define	OMAP_RTC_HAS_KICKER		0x1
>  
> +#define SHUTDOWN_TIME_SEC		2
> +
>  static void __iomem	*rtc_base;
>  
>  #define rtc_read(addr)		readb(rtc_base + (addr))
> @@ -290,6 +304,63 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
>  	return 0;
>  }
>  
> +/*
> + * rtc_power_off: Set the pmic power off sequence. The RTC generates
> + * pmic_pwr_enable control, which can be used to control an external
> + * PMIC.
> + */
> +static void rtc_power_off(void)
> +{
> +	u32 val;
> +	struct rtc_time tm;
> +	spinlock_t lock;
> +	unsigned long flags, time;
> +
> +	spin_lock_init(&lock);
> +
> +	/* Set PMIC power enable */
> +	val = readl(rtc_base + OMAP_RTC_PMIC_REG);
> +	writel(val | OMAP_RTC_PMIC_POWER_EN_EN, rtc_base + OMAP_RTC_PMIC_REG);
> +
> +	/* Read rtc time */
> +	omap_rtc_read_time(NULL, &tm);
> +
> +	/* Convert Gregorian date to seconds since 01-01-1970 00:00:00 */
> +	rtc_tm_to_time(&tm, &time);
> +
> +	/* Add shutdown time to the current value */
> +	time += SHUTDOWN_TIME_SEC;
> +
> +	/* Convert seconds since 01-01-1970 00:00:00 to Gregorian date */
> +	rtc_time_to_tm(time, &tm);
> +
> +	if (tm2bcd(&tm) < 0)
> +		return;
> +
> +	pr_info("System will go to power_off state in approx. %d secs\n",
> +			SHUTDOWN_TIME_SEC);
> +
> +	/*
> +	 * pmic_pwr_enable is controlled by means of ALARM2 event. So here
> +	 * programming alarm2 expiry time and enabling alarm2 interrupt
> +	 */
> +	rtc_write(tm.tm_sec, OMAP_RTC_ALARM2_SECONDS_REG);
> +	rtc_write(tm.tm_min, OMAP_RTC_ALARM2_MINUTES_REG);
> +	rtc_write(tm.tm_hour, OMAP_RTC_ALARM2_HOURS_REG);
> +	rtc_write(tm.tm_mday, OMAP_RTC_ALARM2_DAYS_REG);
> +	rtc_write(tm.tm_mon, OMAP_RTC_ALARM2_MONTHS_REG);
> +	rtc_write(tm.tm_year, OMAP_RTC_ALARM2_YEARS_REG);
> +
> +	/* Enable alarm2 interrupt */
> +	val = readl(rtc_base + OMAP_RTC_INTERRUPTS_REG);
> +	writel(val | OMAP_RTC_INTERRUPTS_IT_ALARM2,
> +				rtc_base + OMAP_RTC_INTERRUPTS_REG);
> +
> +	/* Do not allow to execute any other task */
> +	spin_lock_irqsave(&lock, flags);
> +	while (1);
> +}
> +
>  static struct rtc_class_ops omap_rtc_ops = {
>  	.read_time	= omap_rtc_read_time,
>  	.set_time	= omap_rtc_set_time,
> @@ -327,12 +398,16 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
>  	struct resource		*res, *mem;
>  	struct rtc_device	*rtc;
>  	u8			reg, new_ctrl;
> +	bool			pm_off = false;
>  	const struct platform_device_id *id_entry;
>  	const struct of_device_id *of_id;
>  
>  	of_id = of_match_device(omap_rtc_of_match, &pdev->dev);
> -	if (of_id)
> +	if (of_id) {
>  		pdev->id_entry = of_id->data;
> +		pm_off = of_property_read_bool(pdev->dev.of_node,
> +					"ti,system-power-controller");
> +	}
>  
>  	omap_rtc_timer = platform_get_irq(pdev, 0);
>  	if (omap_rtc_timer <= 0) {
> @@ -385,6 +460,10 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, rtc);
>  	dev_set_drvdata(&rtc->dev, mem);
>  
> +	/* RTC power off */
> +	if (pm_off && !pm_power_off)
> +		pm_power_off = rtc_power_off;
> +
>  	/* clear pending irqs, and set 1/second periodic,
>  	 * which we'll use instead of update irqs
>  	 */
> -- 
> 1.7.9.5
>