RE: [PATCH 2/4] rtc: OMAP: Add system pm_power_off to rtc driver

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On Mon, Nov 05, 2012 at 22:13:25, Cousson, Benoit wrote:
> Hi Anil / Colin,
> 
> On 11/05/2012 10:42 AM, AnilKumar Ch wrote:
> > From: Colin Foe-Parker <colin.foeparker@xxxxxxxxxxx>
> > 
> > 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@xxxxxxxxxxx>
> > [anilkumar@xxxxxx: move poweroff additions to rtc driver]
> > Signed-off-by: AnilKumar Ch <anilkumar@xxxxxx>
> > ---
> >  Documentation/devicetree/bindings/rtc/rtc-omap.txt |    5 ++
> >  drivers/rtc/rtc-omap.c                             |   79 +++++++++++++++++++-
> >  2 files changed, 83 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.
> 
> I don't know how it is connected at board level, but I'm not sure the
> binding is the proper one.

Hi Benoit,
 ________________________________
|   ______          _______      |
|  |      |        |       |     |
|  |RTC   |        |       |     |
|  |PMIC  |  Line  |       |     |
|  |PWR_EN|=======>|PWR_EN |     |
|  |______|        |_______|     |
|  AM335x SoC       TPS65217     |
|                                |
|________________________________|
          BeagleBone

This is how RTC PMIC_PWR_EN is connected to PWR_EN of TPS65217 PMIC. Only when
RTC pull low in PMIC_PWR_EN then PMIC will go to power off state provided TPS65217
status should be changed to STATUS_OFF.

ALARM2 event should be trigger to configure PMIC_PWR_EN properly then the "Line"
driven low so that PMIC will go to shutdown mode.

Thanks
AnilKumar

> It does not look super generic, and I'm wondering if we should not use
> instead some regulator binding to reflect the connection of the RTC to a
> regulator.
> 
> But without the board / soc spec it is hard to tell :-(
>
> Regards,
> Benoit
> 
> 
> > +
> >  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..2d90170 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 +101,24 @@
> >  #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
> > +#define SECS_IN_MIN			60
> > +#define WAIT_AFTER			(SECS_IN_MIN - SHUTDOWN_TIME_SEC)
> > +#define WAIT_TIME_MS			(SHUTDOWN_TIME_SEC * 1000)
> > +
> >  static void __iomem	*rtc_base;
> >  
> >  #define rtc_read(addr)		readb(rtc_base + (addr))
> > @@ -290,6 +307,58 @@ 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;
> > +
> > +	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);
> > +
> > +	/* Wait few seconds instead of rollover */
> > +	do {
> > +		omap_rtc_read_time(NULL, &tm);
> > +		if (WAIT_AFTER <= tm.tm_sec)
> > +			mdelay(WAIT_TIME_MS);
> > +	} while (WAIT_AFTER <= tm.tm_sec);
> > +
> > +	/* Add shutdown time to the current value */
> > +	tm.tm_sec += SHUTDOWN_TIME_SEC;
> > +
> > +	if (tm2bcd(&tm) < 0)
> > +		return;
> > +
> > +	pr_info("System will go to power_off state in approx. %d secs\n",
> > +			SHUTDOWN_TIME_SEC);
> > +
> > +	/* Set the ALARM2 time */
> > +	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 +396,16 @@ 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 +458,10 @@ 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
> >  	 */
> > 
> 
> 

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