Patchwork [2/3] powerpc/mpic: add global timer support

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Submitter Dongsheng Wang
Date March 8, 2013, 7:38 a.m.
Message ID <1362728327-21013-2-git-send-email-dongsheng.wang@freescale.com>
Download mbox | patch
Permalink /patch/226035/
State Superseded
Delegated to: Kumar Gala
Headers show

Comments

Dongsheng Wang - March 8, 2013, 7:38 a.m.
The MPIC global timer is a hardware timer inside the Freescale PIC comply
to Open-PIC standard. When the timer is timeout of the specified interval,
the hardware timer generates an interrupt. The driver currently is only
tested on fsl chip, but it can potentially support other global timers
complying to Open-PIC standard.

The two independent groups of global timer on fsl chip, group A and group B,
are identical in their functionality, except that they appear at different
locations within the PIC register map. The hardware timer can be cascaded to
create timers larger than the default 31-bit global timers. Timer cascade
fields allow configuration of up to two 63-bit timers. But These two groups
of timers cannot be cascaded together.

It can be used as a wakeup source for low power modes. It also could be used
as periodical timer for protocols, drivers and etc.

Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
---
 arch/powerpc/include/asm/mpic_timer.h |   46 +++
 arch/powerpc/platforms/Kconfig        |   12 +
 arch/powerpc/sysdev/Makefile          |    1 +
 arch/powerpc/sysdev/mpic_timer.c      |  606 +++++++++++++++++++++++++++++++++
 4 files changed, 665 insertions(+), 0 deletions(-)
 create mode 100644 arch/powerpc/include/asm/mpic_timer.h
 create mode 100644 arch/powerpc/sysdev/mpic_timer.c
Wang Dongsheng-B40534 - March 19, 2013, 7:55 a.m.
> > +static void convert_ticks_to_time(struct timer_group_priv *priv,
> > +		const u64 ticks, struct timeval *time) {
> > +	u64 tmp_sec;
> > +	u32 rem_us;
> > +	u32 div;
> > +
> > +	if (!(priv->flags & FSL_GLOBAL_TIMER)) {
> > +		time->tv_sec = (__kernel_time_t)
> > +			div_u64_rem(ticks, priv->timerfreq, &rem_us);
> > +		tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> > +		time->tv_usec = (__kernel_suseconds_t)
> > +			div_u64((ticks - tmp_sec) * 1000000,
> > priv->timerfreq);
> > +
> > +		return;
> > +	}
> > +
> > +	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > +
> > +	time->tv_sec = (__kernel_time_t)div_u64(ticks, priv->timerfreq
> > / div);
> > +	tmp_sec = div_u64((u64)time->tv_sec * (u64)priv->timerfreq,
> > div);
> > +
> > +	time->tv_usec = (__kernel_suseconds_t)
> > +		div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq /
> > div);
> > +
> > +	return;
> 
> Why don't you just adjust the clock frequency up front for CLKDIV_64,
> rather than introduce alternate (and untested!) code paths throughout the
> driver?
> 
No, It cannot be integrated. The div cannot be removed.
Because if do priv->timerfreq /= div, that will affect the accuracy.

Like:
3 * 5 / 2 = 7;
3 / 2 * 5 = 5;

BTW
if (!(priv->flags & FSL_GLOBAL_TIMER)) {
	time->tv_sec = (__kernel_time_t)
		div_u64_rem(ticks, priv->timerfreq, &rem_us);
	tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
	time->tv_usec = (__kernel_suseconds_t)
		div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);

	return;
}
This branch I has been tested.

Test methods:
1. Get timerfreq and set timerfreq.
   timerfreq /= 64;(Clock ratio is divide by 64)

2. Clear FSL_GLOBAL_TIMER flag.

Test Log:
[root@p5020 root]# echo 20 > /sys/devices/system/mpic/timer_wakeup
[root@p5020 root]# cat /sys/devices/system/mpic/timer_wakeup
sec = 18, ticks = 118295518.., timerfreq = 6249999..
19
[root@p5020 root]# cat /sys/devices/system/mpic/timer_wakeup
sec = 17, ticks = 110095766.., timerfreq = 6249999..
18
[root@p5020 root]# cat /sys/devices/system/mpic/timer_wakeup
sec = 16, ticks = 105095737.., timerfreq = 6249999..
17
[root@p5020 root]# cat /sys/devices/system/mpic/timer_wakeup
sec = 15, ticks = 99495711.., timerfreq = 6249999..
16
Wang Dongsheng-B40534 - March 20, 2013, 6:45 a.m.
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Wednesday, March 20, 2013 6:59 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; Gala Kumar-B11780; linuxppc-dev@lists.ozlabs.org;
> Li Yang-R58472
> Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> 
> On 03/19/2013 02:55:58 AM, Wang Dongsheng-B40534 wrote:
> > > > +static void convert_ticks_to_time(struct timer_group_priv *priv,
> > > > +		const u64 ticks, struct timeval *time) {
> > > > +	u64 tmp_sec;
> > > > +	u32 rem_us;
> > > > +	u32 div;
> > > > +
> > > > +	if (!(priv->flags & FSL_GLOBAL_TIMER)) {
> > > > +		time->tv_sec = (__kernel_time_t)
> > > > +			div_u64_rem(ticks, priv->timerfreq, &rem_us);
> > > > +		tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> > > > +		time->tv_usec = (__kernel_suseconds_t)
> > > > +			div_u64((ticks - tmp_sec) * 1000000,
> > > > priv->timerfreq);
> > > > +
> > > > +		return;
> > > > +	}
> > > > +
> > > > +	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > > > +
> > > > +	time->tv_sec = (__kernel_time_t)div_u64(ticks, priv-
> >timerfreq
> > > > / div);
> > > > +	tmp_sec = div_u64((u64)time->tv_sec * (u64)priv->timerfreq,
> > > > div);
> > > > +
> > > > +	time->tv_usec = (__kernel_suseconds_t)
> > > > +		div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq /
> > > > div);
> > > > +
> > > > +	return;
> > >
> > > Why don't you just adjust the clock frequency up front for
> > CLKDIV_64,
> > > rather than introduce alternate (and untested!) code paths
> > throughout the
> > > driver?
> > >
> > No, It cannot be integrated. The div cannot be removed.
> > Because if do priv->timerfreq /= div, that will affect the accuracy.
> >
> > Like:
> > 3 * 5 / 2 = 7;
> > 3 / 2 * 5 = 5;
> 
> I don't follow -- a change in the clock speed is a change in the clock
> speed, no matter how you accomplish it.
> 
This is not change hardware clock frequency. The mpic timer hardware clock
is not be changed after initialization. This is just conversion ticks.
These calculated ticks will be set to the hardware.

> How you round is a different question.  You should probably be rounding
> up always, based on the final clock frequency -- though it's unlikely to
> matter much given the high precision of the timer relative to the input
> granularity.
> 
Each ticks are based on the mpic timer hardware clock frequency.
The conversion and calculation are in order to make the tick value is more
accurate, more close to real time.
If echo 40 seconds may be difference is not obvious. But echo 315360000(10 years)
difference is obvious.
Wang Dongsheng-B40534 - March 22, 2013, 6:14 a.m.
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Thursday, March 21, 2013 7:00 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; Gala Kumar-B11780; linuxppc-dev@lists.ozlabs.org;
> Li Yang-R58472
> Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> 
> On 03/20/2013 01:45:03 AM, Wang Dongsheng-B40534 wrote:
> >
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Wednesday, March 20, 2013 6:59 AM
> > > To: Wang Dongsheng-B40534
> > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > linuxppc-dev@lists.ozlabs.org;
> > > Li Yang-R58472
> > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > >
> > > On 03/19/2013 02:55:58 AM, Wang Dongsheng-B40534 wrote:
> > > > > > +static void convert_ticks_to_time(struct timer_group_priv
> > *priv,
> > > > > > +		const u64 ticks, struct timeval *time) {
> > > > > > +	u64 tmp_sec;
> > > > > > +	u32 rem_us;
> > > > > > +	u32 div;
> > > > > > +
> > > > > > +	if (!(priv->flags & FSL_GLOBAL_TIMER)) {
> > > > > > +		time->tv_sec = (__kernel_time_t)
> > > > > > +			div_u64_rem(ticks, priv->timerfreq,
> > &rem_us);
> > > > > > +		tmp_sec = (u64)time->tv_sec *
> > (u64)priv->timerfreq;
> > > > > > +		time->tv_usec = (__kernel_suseconds_t)
> > > > > > +			div_u64((ticks - tmp_sec) * 1000000,
> > > > > > priv->timerfreq);
> > > > > > +
> > > > > > +		return;
> > > > > > +	}
> > > > > > +
> > > > > > +	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > > > > > +
> > > > > > +	time->tv_sec = (__kernel_time_t)div_u64(ticks, priv-
> > > >timerfreq
> > > > > > / div);
> > > > > > +	tmp_sec = div_u64((u64)time->tv_sec *
> > (u64)priv->timerfreq,
> > > > > > div);
> > > > > > +
> > > > > > +	time->tv_usec = (__kernel_suseconds_t)
> > > > > > +		div_u64((ticks - tmp_sec) * 1000000,
> > priv->timerfreq /
> > > > > > div);
> > > > > > +
> > > > > > +	return;
> > > > >
> > > > > Why don't you just adjust the clock frequency up front for
> > > > CLKDIV_64,
> > > > > rather than introduce alternate (and untested!) code paths
> > > > throughout the
> > > > > driver?
> > > > >
> > > > No, It cannot be integrated. The div cannot be removed.
> > > > Because if do priv->timerfreq /= div, that will affect the
> > accuracy.
> > > >
> > > > Like:
> > > > 3 * 5 / 2 = 7;
> > > > 3 / 2 * 5 = 5;
> > >
> > > I don't follow -- a change in the clock speed is a change in the
> > clock
> > > speed, no matter how you accomplish it.
> > >
> > This is not change hardware clock frequency.
> 
> Citation needed.  It looks like a change in the timer frequency to me:
> 
>    Clock ratio. Specifies the ratio of the timer frequency to the MPIC
> input clock (platform clock/2) . The
>    following clock ratios are supported:
>    00
>    01
>    10
>    11
>    Default. Divide by 8
>    Divide by 16
>    Divide by 32
>    Divide by 64
> 
> The end result is that the counter in the timer register changes only
> 1/64 as often as the input clock.  There's nothing special about that,
> compared to having an input clock that is 1/64 the speed.
> 
> > The mpic timer hardware clock is not be changed after initialization.
> > This is just conversion ticks.
> > These calculated ticks will be set to the hardware.
> >
> > > How you round is a different question.  You should probably be
> > rounding
> > > up always, based on the final clock frequency -- though it's
> > unlikely to
> > > matter much given the high precision of the timer relative to the
> > input
> > > granularity.
> > >
> > Each ticks are based on the mpic timer hardware clock frequency.
> > The conversion and calculation are in order to make the tick value is
> > more
> > accurate, more close to real time.
> > If echo 40 seconds may be difference is not obvious. But echo
> > 315360000(10 years)
> > difference is obvious.
> 
> So basically you're taking advantage of the fact that you have what
> appears to be a more precise value of the frequency than is expressible
> in integer Hz -- but I think that's false precision; odds are the
> frequency is not accurate to 1 Hz to begin with.  Even if it is, I doubt
> it's worth worrying about.  The error as a percentage will still be very
> small with an input frequency of many MHz.  Does an error of a few
> minutes really matter if you're delaying for 10 years?  That's
> acceptable
> clock drift for something not synced to network time.  The main thing is
> to ensure that you round up, not down, so that software doesn't see an
> early wakeup as measured by its own timers.
> 
> BTW, the input clock frequency has been similarly scaled, yet you don't
> try to scrounge up that information to get further precision...
> 
Let's go back patch, do you think the code is repeated?
I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))" branch, there will be no redundant code.
Wang Dongsheng-B40534 - March 26, 2013, 3:29 a.m.
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Saturday, March 23, 2013 6:30 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; Gala Kumar-B11780; linuxppc-dev@lists.ozlabs.org;
> Li Yang-R58472
> Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> 
> On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> >
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Thursday, March 21, 2013 7:00 AM
> > > To: Wang Dongsheng-B40534
> > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > linuxppc-dev@lists.ozlabs.org;
> > > Li Yang-R58472
> > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > >
> > > BTW, the input clock frequency has been similarly scaled, yet you
> > don't
> > > try to scrounge up that information to get further precision...
> > >
> > Let's go back patch, do you think the code is repeated?
> > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))" branch, there
> > will be no redundant code.
> 
> I'd rather that branch be kept and the more complicated branch deleted,
> and priv->timerfreq frequency be adjusted on initialization to account
> for the scaler.

static void convert_ticks_to_time(struct timer_group_priv *priv,
                const u64 ticks, struct timeval *time)
{
        u64 tmp_sec;

        time->tv_sec = (__kernel_time_t)div_u64(ticks, priv->timerfreq);
        tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;

        time->tv_usec = (__kernel_suseconds_t)
                div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);

        return;
}

timer_group_get_freq() {
	...
	if (priv->flags & FSL_GLOBAL_TIMER) {
		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
		priv->timerfreq /= div;
	}
	...
}
Do you want to do that?
Scott Wood - March 26, 2013, 5:31 p.m.
On 03/25/2013 10:29:58 PM, Wang Dongsheng-B40534 wrote:
> 
> 
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Saturday, March 23, 2013 6:30 AM
> > To: Wang Dongsheng-B40534
> > Cc: Wood Scott-B07421; Gala Kumar-B11780;  
> linuxppc-dev@lists.ozlabs.org;
> > Li Yang-R58472
> > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> >
> > On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Wood Scott-B07421
> > > > Sent: Thursday, March 21, 2013 7:00 AM
> > > > To: Wang Dongsheng-B40534
> > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > linuxppc-dev@lists.ozlabs.org;
> > > > Li Yang-R58472
> > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > > >
> > > > BTW, the input clock frequency has been similarly scaled, yet  
> you
> > > don't
> > > > try to scrounge up that information to get further precision...
> > > >
> > > Let's go back patch, do you think the code is repeated?
> > > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))" branch,  
> there
> > > will be no redundant code.
> >
> > I'd rather that branch be kept and the more complicated branch  
> deleted,
> > and priv->timerfreq frequency be adjusted on initialization to  
> account
> > for the scaler.
> 
> static void convert_ticks_to_time(struct timer_group_priv *priv,
>                 const u64 ticks, struct timeval *time)
> {
>         u64 tmp_sec;
> 
>         time->tv_sec = (__kernel_time_t)div_u64(ticks,  
> priv->timerfreq);
>         tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> 
>         time->tv_usec = (__kernel_suseconds_t)
>                 div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
> 
>         return;
> }
> 
> timer_group_get_freq() {
> 	...
> 	if (priv->flags & FSL_GLOBAL_TIMER) {
> 		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> 		priv->timerfreq /= div;
> 	}
> 	...
> }
> Do you want to do that?

	if (priv->flags & FSL_GLOBAL_TIMER)
		priv->timerfreq /= 64;

...but otherwise yes.

-Scott
Wang Dongsheng-B40534 - March 27, 2013, 3:23 a.m.
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Wednesday, March 27, 2013 1:32 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; Gala Kumar-B11780; linuxppc-dev@lists.ozlabs.org;
> Li Yang-R58472
> Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> 
> On 03/25/2013 10:29:58 PM, Wang Dongsheng-B40534 wrote:
> >
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Saturday, March 23, 2013 6:30 AM
> > > To: Wang Dongsheng-B40534
> > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > linuxppc-dev@lists.ozlabs.org;
> > > Li Yang-R58472
> > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > >
> > > On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Wood Scott-B07421
> > > > > Sent: Thursday, March 21, 2013 7:00 AM
> > > > > To: Wang Dongsheng-B40534
> > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > linuxppc-dev@lists.ozlabs.org;
> > > > > Li Yang-R58472
> > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > > > >
> > > > > BTW, the input clock frequency has been similarly scaled, yet
> > you
> > > > don't
> > > > > try to scrounge up that information to get further precision...
> > > > >
> > > > Let's go back patch, do you think the code is repeated?
> > > > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))" branch,
> > there
> > > > will be no redundant code.
> > >
> > > I'd rather that branch be kept and the more complicated branch
> > deleted,
> > > and priv->timerfreq frequency be adjusted on initialization to
> > account
> > > for the scaler.
> >
> > static void convert_ticks_to_time(struct timer_group_priv *priv,
> >                 const u64 ticks, struct timeval *time) {
> >         u64 tmp_sec;
> >
> >         time->tv_sec = (__kernel_time_t)div_u64(ticks,
> > priv->timerfreq);
> >         tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> >
> >         time->tv_usec = (__kernel_suseconds_t)
> >                 div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
> >
> >         return;
> > }
> >
> > timer_group_get_freq() {
> > 	...
> > 	if (priv->flags & FSL_GLOBAL_TIMER) {
> > 		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > 		priv->timerfreq /= div;
> > 	}
> > 	...
> > }
> > Do you want to do that?
> 
> 	if (priv->flags & FSL_GLOBAL_TIMER)
> 		priv->timerfreq /= 64;
> 
> ...but otherwise yes.
Ok, I would like do this.

if (priv->flags & FSL_GLOBAL_TIMER) {
	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
	priv->timerfreq /= div;
}
Scott Wood - March 27, 2013, 5:11 p.m.
On 03/26/2013 10:23:38 PM, Wang Dongsheng-B40534 wrote:
> 
> 
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Wednesday, March 27, 2013 1:32 AM
> > To: Wang Dongsheng-B40534
> > Cc: Wood Scott-B07421; Gala Kumar-B11780;  
> linuxppc-dev@lists.ozlabs.org;
> > Li Yang-R58472
> > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> >
> > On 03/25/2013 10:29:58 PM, Wang Dongsheng-B40534 wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Wood Scott-B07421
> > > > Sent: Saturday, March 23, 2013 6:30 AM
> > > > To: Wang Dongsheng-B40534
> > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > linuxppc-dev@lists.ozlabs.org;
> > > > Li Yang-R58472
> > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > > >
> > > > On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Wood Scott-B07421
> > > > > > Sent: Thursday, March 21, 2013 7:00 AM
> > > > > > To: Wang Dongsheng-B40534
> > > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > > linuxppc-dev@lists.ozlabs.org;
> > > > > > Li Yang-R58472
> > > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer  
> support
> > > > > >
> > > > > > BTW, the input clock frequency has been similarly scaled,  
> yet
> > > you
> > > > > don't
> > > > > > try to scrounge up that information to get further  
> precision...
> > > > > >
> > > > > Let's go back patch, do you think the code is repeated?
> > > > > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))" branch,
> > > there
> > > > > will be no redundant code.
> > > >
> > > > I'd rather that branch be kept and the more complicated branch
> > > deleted,
> > > > and priv->timerfreq frequency be adjusted on initialization to
> > > account
> > > > for the scaler.
> > >
> > > static void convert_ticks_to_time(struct timer_group_priv *priv,
> > >                 const u64 ticks, struct timeval *time) {
> > >         u64 tmp_sec;
> > >
> > >         time->tv_sec = (__kernel_time_t)div_u64(ticks,
> > > priv->timerfreq);
> > >         tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> > >
> > >         time->tv_usec = (__kernel_suseconds_t)
> > >                 div_u64((ticks - tmp_sec) * 1000000,  
> priv->timerfreq);
> > >
> > >         return;
> > > }
> > >
> > > timer_group_get_freq() {
> > > 	...
> > > 	if (priv->flags & FSL_GLOBAL_TIMER) {
> > > 		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > > 		priv->timerfreq /= div;
> > > 	}
> > > 	...
> > > }
> > > Do you want to do that?
> >
> > 	if (priv->flags & FSL_GLOBAL_TIMER)
> > 		priv->timerfreq /= 64;
> >
> > ...but otherwise yes.
> Ok, I would like do this.
> 
> if (priv->flags & FSL_GLOBAL_TIMER) {
> 	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> 	priv->timerfreq /= div;

Why?  What do you get out of that obfuscation?

-Scott
Wang Dongsheng-B40534 - March 28, 2013, 2:29 a.m.
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Thursday, March 28, 2013 1:12 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; Gala Kumar-B11780; linuxppc-dev@lists.ozlabs.org;
> Li Yang-R58472
> Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> 
> On 03/26/2013 10:23:38 PM, Wang Dongsheng-B40534 wrote:
> >
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Wednesday, March 27, 2013 1:32 AM
> > > To: Wang Dongsheng-B40534
> > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > linuxppc-dev@lists.ozlabs.org;
> > > Li Yang-R58472
> > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > >
> > > On 03/25/2013 10:29:58 PM, Wang Dongsheng-B40534 wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Wood Scott-B07421
> > > > > Sent: Saturday, March 23, 2013 6:30 AM
> > > > > To: Wang Dongsheng-B40534
> > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > linuxppc-dev@lists.ozlabs.org;
> > > > > Li Yang-R58472
> > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > > > >
> > > > > On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> > > > > >
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Wood Scott-B07421
> > > > > > > Sent: Thursday, March 21, 2013 7:00 AM
> > > > > > > To: Wang Dongsheng-B40534
> > > > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > > > linuxppc-dev@lists.ozlabs.org;
> > > > > > > Li Yang-R58472
> > > > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer
> > support
> > > > > > >
> > > > > > > BTW, the input clock frequency has been similarly scaled,
> > yet
> > > > you
> > > > > > don't
> > > > > > > try to scrounge up that information to get further
> > precision...
> > > > > > >
> > > > > > Let's go back patch, do you think the code is repeated?
> > > > > > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))" branch,
> > > > there
> > > > > > will be no redundant code.
> > > > >
> > > > > I'd rather that branch be kept and the more complicated branch
> > > > deleted,
> > > > > and priv->timerfreq frequency be adjusted on initialization to
> > > > account
> > > > > for the scaler.
> > > >
> > > > static void convert_ticks_to_time(struct timer_group_priv *priv,
> > > >                 const u64 ticks, struct timeval *time) {
> > > >         u64 tmp_sec;
> > > >
> > > >         time->tv_sec = (__kernel_time_t)div_u64(ticks,
> > > > priv->timerfreq);
> > > >         tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> > > >
> > > >         time->tv_usec = (__kernel_suseconds_t)
> > > >                 div_u64((ticks - tmp_sec) * 1000000,
> > priv->timerfreq);
> > > >
> > > >         return;
> > > > }
> > > >
> > > > timer_group_get_freq() {
> > > > 	...
> > > > 	if (priv->flags & FSL_GLOBAL_TIMER) {
> > > > 		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > > > 		priv->timerfreq /= div;
> > > > 	}
> > > > 	...
> > > > }
> > > > Do you want to do that?
> > >
> > > 	if (priv->flags & FSL_GLOBAL_TIMER)
> > > 		priv->timerfreq /= 64;
> > >
> > > ...but otherwise yes.
> > Ok, I would like do this.
> >
> > if (priv->flags & FSL_GLOBAL_TIMER) {
> > 	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > 	priv->timerfreq /= div;
> 
> Why?  What do you get out of that obfuscation?
> 
Change MPIC_TIMER_TCR_CLKDIV_64 to MPIC_TIMER_TCR_CLKDIV

/* Clock Ratio
 * Divide by 64 0x00000300
 * Divide by 32 0x00000200
 * Divide by 16 0x00000100
 * Divide by  8 0x00000000 (Hardware default div)
 */
#define MPIC_TIMER_TCR_CLKDIV 0x00000300

timer_group_init() {
	...
	/* Init FSL timer hardware */
      if (priv->flags & FSL_GLOBAL_TIMER)
      	setbits32(priv->group_tcr, MPIC_TIMER_TCR_CLKDIV);
	...
}

mpic_timer_resume() {
	...
	/* Init FSL timer hardware */
      if (priv->flags & FSL_GLOBAL_TIMER)
      	setbits32(priv->group_tcr, MPIC_TIMER_TCR_CLKDIV);
	...
}

Because macro is friendly, and other functions also used the macro.
Scott Wood - March 28, 2013, 7:47 p.m.
On 03/27/2013 09:29:26 PM, Wang Dongsheng-B40534 wrote:
> 
> 
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Thursday, March 28, 2013 1:12 AM
> > To: Wang Dongsheng-B40534
> > Cc: Wood Scott-B07421; Gala Kumar-B11780;  
> linuxppc-dev@lists.ozlabs.org;
> > Li Yang-R58472
> > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> >
> > On 03/26/2013 10:23:38 PM, Wang Dongsheng-B40534 wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Wood Scott-B07421
> > > > Sent: Wednesday, March 27, 2013 1:32 AM
> > > > To: Wang Dongsheng-B40534
> > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > linuxppc-dev@lists.ozlabs.org;
> > > > Li Yang-R58472
> > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > > >
> > > > On 03/25/2013 10:29:58 PM, Wang Dongsheng-B40534 wrote:
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Wood Scott-B07421
> > > > > > Sent: Saturday, March 23, 2013 6:30 AM
> > > > > > To: Wang Dongsheng-B40534
> > > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > > linuxppc-dev@lists.ozlabs.org;
> > > > > > Li Yang-R58472
> > > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer  
> support
> > > > > >
> > > > > > On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> > > > > > >
> > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: Wood Scott-B07421
> > > > > > > > Sent: Thursday, March 21, 2013 7:00 AM
> > > > > > > > To: Wang Dongsheng-B40534
> > > > > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > > > > linuxppc-dev@lists.ozlabs.org;
> > > > > > > > Li Yang-R58472
> > > > > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer
> > > support
> > > > > > > >
> > > > > > > > BTW, the input clock frequency has been similarly  
> scaled,
> > > yet
> > > > > you
> > > > > > > don't
> > > > > > > > try to scrounge up that information to get further
> > > precision...
> > > > > > > >
> > > > > > > Let's go back patch, do you think the code is repeated?
> > > > > > > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))"  
> branch,
> > > > > there
> > > > > > > will be no redundant code.
> > > > > >
> > > > > > I'd rather that branch be kept and the more complicated  
> branch
> > > > > deleted,
> > > > > > and priv->timerfreq frequency be adjusted on initialization  
> to
> > > > > account
> > > > > > for the scaler.
> > > > >
> > > > > static void convert_ticks_to_time(struct timer_group_priv  
> *priv,
> > > > >                 const u64 ticks, struct timeval *time) {
> > > > >         u64 tmp_sec;
> > > > >
> > > > >         time->tv_sec = (__kernel_time_t)div_u64(ticks,
> > > > > priv->timerfreq);
> > > > >         tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> > > > >
> > > > >         time->tv_usec = (__kernel_suseconds_t)
> > > > >                 div_u64((ticks - tmp_sec) * 1000000,
> > > priv->timerfreq);
> > > > >
> > > > >         return;
> > > > > }
> > > > >
> > > > > timer_group_get_freq() {
> > > > > 	...
> > > > > 	if (priv->flags & FSL_GLOBAL_TIMER) {
> > > > > 		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) *  
> 8;
> > > > > 		priv->timerfreq /= div;
> > > > > 	}
> > > > > 	...
> > > > > }
> > > > > Do you want to do that?
> > > >
> > > > 	if (priv->flags & FSL_GLOBAL_TIMER)
> > > > 		priv->timerfreq /= 64;
> > > >
> > > > ...but otherwise yes.
> > > Ok, I would like do this.
> > >
> > > if (priv->flags & FSL_GLOBAL_TIMER) {
> > > 	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > > 	priv->timerfreq /= div;
> >
> > Why?  What do you get out of that obfuscation?
> >
> Change MPIC_TIMER_TCR_CLKDIV_64 to MPIC_TIMER_TCR_CLKDIV

OK, that would at least provide the ability to adjust the clock divider  
in one place rather than two -- though I don't know why we'd ever need  
to change the divider.

> Because macro is friendly, and other functions also used the macro.

Using the macro rather than hardcoding register bit encodings is  
friendly.  The calculation to turn the bit encoding into an actual  
divider value is not particularly friendly.

-Scott
Wang Dongsheng-B40534 - March 29, 2013, 1:58 a.m.
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Friday, March 29, 2013 3:48 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; Gala Kumar-B11780; linuxppc-dev@lists.ozlabs.org;
> Li Yang-R58472
> Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> 
> On 03/27/2013 09:29:26 PM, Wang Dongsheng-B40534 wrote:
> >
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Thursday, March 28, 2013 1:12 AM
> > > To: Wang Dongsheng-B40534
> > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > linuxppc-dev@lists.ozlabs.org;
> > > Li Yang-R58472
> > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > >
> > > On 03/26/2013 10:23:38 PM, Wang Dongsheng-B40534 wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Wood Scott-B07421
> > > > > Sent: Wednesday, March 27, 2013 1:32 AM
> > > > > To: Wang Dongsheng-B40534
> > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > linuxppc-dev@lists.ozlabs.org;
> > > > > Li Yang-R58472
> > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer support
> > > > >
> > > > > On 03/25/2013 10:29:58 PM, Wang Dongsheng-B40534 wrote:
> > > > > >
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Wood Scott-B07421
> > > > > > > Sent: Saturday, March 23, 2013 6:30 AM
> > > > > > > To: Wang Dongsheng-B40534
> > > > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > > > linuxppc-dev@lists.ozlabs.org;
> > > > > > > Li Yang-R58472
> > > > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer
> > support
> > > > > > >
> > > > > > > On 03/22/2013 01:14:51 AM, Wang Dongsheng-B40534 wrote:
> > > > > > > >
> > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: Wood Scott-B07421
> > > > > > > > > Sent: Thursday, March 21, 2013 7:00 AM
> > > > > > > > > To: Wang Dongsheng-B40534
> > > > > > > > > Cc: Wood Scott-B07421; Gala Kumar-B11780;
> > > > > > > > linuxppc-dev@lists.ozlabs.org;
> > > > > > > > > Li Yang-R58472
> > > > > > > > > Subject: Re: [PATCH 2/3] powerpc/mpic: add global timer
> > > > support
> > > > > > > > >
> > > > > > > > > BTW, the input clock frequency has been similarly
> > scaled,
> > > > yet
> > > > > > you
> > > > > > > > don't
> > > > > > > > > try to scrounge up that information to get further
> > > > precision...
> > > > > > > > >
> > > > > > > > Let's go back patch, do you think the code is repeated?
> > > > > > > > I will remove "if (!(priv->flags & FSL_GLOBAL_TIMER))"
> > branch,
> > > > > > there
> > > > > > > > will be no redundant code.
> > > > > > >
> > > > > > > I'd rather that branch be kept and the more complicated
> > branch
> > > > > > deleted,
> > > > > > > and priv->timerfreq frequency be adjusted on initialization
> > to
> > > > > > account
> > > > > > > for the scaler.
> > > > > >
> > > > > > static void convert_ticks_to_time(struct timer_group_priv
> > *priv,
> > > > > >                 const u64 ticks, struct timeval *time) {
> > > > > >         u64 tmp_sec;
> > > > > >
> > > > > >         time->tv_sec = (__kernel_time_t)div_u64(ticks,
> > > > > > priv->timerfreq);
> > > > > >         tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
> > > > > >
> > > > > >         time->tv_usec = (__kernel_suseconds_t)
> > > > > >                 div_u64((ticks - tmp_sec) * 1000000,
> > > > priv->timerfreq);
> > > > > >
> > > > > >         return;
> > > > > > }
> > > > > >
> > > > > > timer_group_get_freq() {
> > > > > > 	...
> > > > > > 	if (priv->flags & FSL_GLOBAL_TIMER) {
> > > > > > 		div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) *
> > 8;
> > > > > > 		priv->timerfreq /= div;
> > > > > > 	}
> > > > > > 	...
> > > > > > }
> > > > > > Do you want to do that?
> > > > >
> > > > > 	if (priv->flags & FSL_GLOBAL_TIMER)
> > > > > 		priv->timerfreq /= 64;
> > > > >
> > > > > ...but otherwise yes.
> > > > Ok, I would like do this.
> > > >
> > > > if (priv->flags & FSL_GLOBAL_TIMER) {
> > > > 	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
> > > > 	priv->timerfreq /= div;
> > >
> > > Why?  What do you get out of that obfuscation?
> > >
> > Change MPIC_TIMER_TCR_CLKDIV_64 to MPIC_TIMER_TCR_CLKDIV
> 
> OK, that would at least provide the ability to adjust the clock divider
> in one place rather than two -- though I don't know why we'd ever need to
> change the divider.
> 
Thanks, next patch MPIC_TIMER_TCR_CLKDIV_64 will change to MPIC_TIMER_TCR_CLKDIV. :)

div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8 --->> div = (1 << (MPIC_TIMER_TCR_CLKDIV >> 8)) * 8;

Patch

diff --git a/arch/powerpc/include/asm/mpic_timer.h b/arch/powerpc/include/asm/mpic_timer.h
new file mode 100644
index 0000000..0e23cd4
--- /dev/null
+++ b/arch/powerpc/include/asm/mpic_timer.h
@@ -0,0 +1,46 @@ 
+/*
+ * arch/powerpc/include/asm/mpic_timer.h
+ *
+ * Header file for Mpic Global Timer
+ *
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ *
+ * Author: Wang Dongsheng <Dongsheng.Wang@freescale.com>
+ *	   Li Yang <leoli@freescale.com>
+ *
+ * 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.
+ */
+
+#ifndef __MPIC_TIMER__
+#define __MPIC_TIMER__
+
+#include <linux/interrupt.h>
+#include <linux/time.h>
+
+struct mpic_timer {
+	void			*dev;
+	struct cascade_priv	*cascade_handle;
+	unsigned int		num;
+	unsigned int		irq;
+};
+
+#ifdef CONFIG_MPIC_TIMER
+struct mpic_timer *mpic_request_timer(irq_handler_t fn,  void *dev,
+		const struct timeval *time);
+void mpic_start_timer(struct mpic_timer *handle);
+void mpic_stop_timer(struct mpic_timer *handle);
+void mpic_get_remain_time(struct mpic_timer *handle, struct timeval *time);
+void mpic_free_timer(struct mpic_timer *handle);
+#else
+struct mpic_timer *mpic_request_timer(irq_handler_t fn,  void *dev,
+		const struct timeval *time) { return NULL; }
+void mpic_start_timer(struct mpic_timer *handle) { }
+void mpic_stop_timer(struct mpic_timer *handle) { }
+void mpic_get_remain_time(struct mpic_timer *handle, struct timeval *time) { }
+void mpic_free_timer(struct mpic_timer *handle) { }
+#endif
+
+#endif
diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index 48a920d..5af04fa 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -87,6 +87,18 @@  config MPIC
 	bool
 	default n
 
+config MPIC_TIMER
+	bool "MPIC Global Timer"
+	depends on MPIC && FSL_SOC
+	default n
+	help
+	  The MPIC global timer is a hardware timer inside the
+	  Freescale PIC comply to Open-PIC standard. When the
+	  timer is timeout of the specified interval, the hardware
+	  timer generates an interrupt. The driver currently is
+	  only tested on fsl chip, but it can potentially support
+	  other global timers complying to Open-PIC standard.
+
 config PPC_EPAPR_HV_PIC
 	bool
 	default n
diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
index a57600b..ff6184a 100644
--- a/arch/powerpc/sysdev/Makefile
+++ b/arch/powerpc/sysdev/Makefile
@@ -4,6 +4,7 @@  ccflags-$(CONFIG_PPC64)		:= -mno-minimal-toc
 
 mpic-msi-obj-$(CONFIG_PCI_MSI)	+= mpic_msi.o mpic_u3msi.o mpic_pasemi_msi.o
 obj-$(CONFIG_MPIC)		+= mpic.o $(mpic-msi-obj-y)
+obj-$(CONFIG_MPIC_TIMER)        += mpic_timer.o
 mpic-msgr-obj-$(CONFIG_MPIC_MSGR)	+= mpic_msgr.o
 obj-$(CONFIG_MPIC)		+= mpic.o $(mpic-msi-obj-y) $(mpic-msgr-obj-y)
 obj-$(CONFIG_PPC_EPAPR_HV_PIC)	+= ehv_pic.o
diff --git a/arch/powerpc/sysdev/mpic_timer.c b/arch/powerpc/sysdev/mpic_timer.c
new file mode 100644
index 0000000..3aaa3d4
--- /dev/null
+++ b/arch/powerpc/sysdev/mpic_timer.c
@@ -0,0 +1,606 @@ 
+/*
+ * MPIC timer driver
+ *
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ * Author: Dongsheng Wang <Dongsheng.Wang@freescale.com>
+ *	   Li Yang <leoli@freescale.com>
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/syscore_ops.h>
+#include <sysdev/fsl_soc.h>
+#include <asm/io.h>
+
+#include <asm/mpic_timer.h>
+
+#define FSL_GLOBAL_TIMER		0x1
+
+#define MPIC_TIMER_TCR_CLKDIV_64	0x00000300
+#define MPIC_TIMER_TCR_ROVR_OFFSET	24
+
+#define TIMER_STOP			0x80000000
+#define TIMERS_PER_GROUP		4
+#define MAX_TICKS			(~0U >> 1)
+#define MAX_TICKS_CASCADE		(~0U)
+#define TIMER_OFFSET(num)		(1 << (TIMERS_PER_GROUP - 1 - num))
+
+/* tv_usec should be less than ONE_SECOND, otherwise use tv_sec */
+#define ONE_SECOND			1000000
+
+struct timer_regs {
+	u32	gtccr;
+	u32	res0[3];
+	u32	gtbcr;
+	u32	res1[3];
+	u32	gtvpr;
+	u32	res2[3];
+	u32	gtdr;
+	u32	res3[3];
+};
+
+struct cascade_priv {
+	u32 tcr_value;			/* TCR register: CASC & ROVR value */
+	unsigned int cascade_map;	/* cascade map */
+	unsigned int timer_num;		/* cascade control timer */
+};
+
+struct timer_group_priv {
+	struct timer_regs __iomem	*regs;
+	struct mpic_timer		timer[TIMERS_PER_GROUP];
+	struct list_head		node;
+	unsigned int			timerfreq;
+	unsigned int			idle;
+	unsigned int			flags;
+	spinlock_t			lock;
+	void __iomem			*group_tcr;
+};
+
+static struct cascade_priv cascade_timer[] = {
+	/* cascade timer 0 and 1 */
+	{0x1, 0xc, 0x1},
+	/* cascade timer 1 and 2 */
+	{0x2, 0x6, 0x2},
+	/* cascade timer 2 and 3 */
+	{0x4, 0x3, 0x3}
+};
+
+static LIST_HEAD(timer_group_list);
+
+static void convert_ticks_to_time(struct timer_group_priv *priv,
+		const u64 ticks, struct timeval *time)
+{
+	u64 tmp_sec;
+	u32 rem_us;
+	u32 div;
+
+	if (!(priv->flags & FSL_GLOBAL_TIMER)) {
+		time->tv_sec = (__kernel_time_t)
+			div_u64_rem(ticks, priv->timerfreq, &rem_us);
+		tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
+		time->tv_usec = (__kernel_suseconds_t)
+			div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
+
+		return;
+	}
+
+	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
+
+	time->tv_sec = (__kernel_time_t)div_u64(ticks, priv->timerfreq / div);
+	tmp_sec = div_u64((u64)time->tv_sec * (u64)priv->timerfreq, div);
+
+	time->tv_usec = (__kernel_suseconds_t)
+		div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq / div);
+
+	return;
+}
+
+/* the time set by the user is converted to "ticks" */
+static int convert_time_to_ticks(struct timer_group_priv *priv,
+		const struct timeval *time, u64 *ticks)
+{
+	u64 max_value;		/* prevent u64 overflow */
+	u64 tmp = 0;
+
+	u64 tmp_sec;
+	u64 tmp_ms;
+	u64 tmp_us;
+	u32 div;
+
+	max_value = div_u64(ULLONG_MAX, priv->timerfreq);
+
+	if (time->tv_sec > max_value ||
+			(time->tv_sec == max_value && time->tv_usec > 0))
+		return -EINVAL;
+
+	if (!(priv->flags & FSL_GLOBAL_TIMER)) {
+		tmp_sec = time->tv_sec * priv->timerfreq;
+		tmp_ms = time->tv_usec / 1000 * priv->timerfreq / 1000;
+		tmp_us = time->tv_usec % 1000 * priv->timerfreq / 1000000;
+
+		*ticks = tmp_sec + tmp_ms + tmp_us;
+
+		return 0;
+	}
+
+	div = (1 << (MPIC_TIMER_TCR_CLKDIV_64 >> 8)) * 8;
+
+	tmp_sec = div_u64((u64)time->tv_sec * (u64)priv->timerfreq, div);
+	tmp += tmp_sec;
+
+	tmp_ms = time->tv_usec / 1000;
+	tmp_ms = div_u64((u64)tmp_ms * (u64)priv->timerfreq, div * 1000);
+	tmp += tmp_ms;
+
+	tmp_us = time->tv_usec % 1000;
+	tmp_us = div_u64((u64)tmp_us * (u64)priv->timerfreq, div * 1000000);
+	tmp += tmp_us;
+
+	*ticks = tmp;
+
+	return 0;
+}
+
+/* detect whether there is a cascade timer available */
+static struct mpic_timer *detect_idle_cascade_timer(
+					struct timer_group_priv *priv)
+{
+	struct cascade_priv *casc_priv;
+	unsigned int map;
+	unsigned int array_size = ARRAY_SIZE(cascade_timer);
+	unsigned int num;
+	unsigned int i;
+	unsigned long flags;
+
+	casc_priv = cascade_timer;
+	for (i = 0; i < array_size; i++) {
+		spin_lock_irqsave(&priv->lock, flags);
+		map = casc_priv->cascade_map & priv->idle;
+		if (map == casc_priv->cascade_map) {
+			num = casc_priv->timer_num;
+			priv->timer[num].cascade_handle = casc_priv;
+
+			/* set timer busy */
+			priv->idle &= ~casc_priv->cascade_map;
+			spin_unlock_irqrestore(&priv->lock, flags);
+			return &priv->timer[num];
+		}
+		spin_unlock_irqrestore(&priv->lock, flags);
+		casc_priv++;
+	}
+
+	return NULL;
+}
+
+static int set_cascade_timer(struct timer_group_priv *priv, u64 ticks,
+		unsigned int num)
+{
+	struct cascade_priv *casc_priv;
+	u32 tcr;
+	u32 tmp_ticks;
+	u32 rem_ticks;
+
+	/* set group tcr reg for cascade */
+	casc_priv = priv->timer[num].cascade_handle;
+	if (!casc_priv)
+		return -EINVAL;
+
+	tcr = casc_priv->tcr_value |
+		(casc_priv->tcr_value << MPIC_TIMER_TCR_ROVR_OFFSET);
+	setbits32(priv->group_tcr, tcr);
+
+	tmp_ticks = div_u64_rem(ticks, MAX_TICKS_CASCADE, &rem_ticks);
+
+	out_be32(&priv->regs[num].gtccr, 0);
+	out_be32(&priv->regs[num].gtbcr, tmp_ticks | TIMER_STOP);
+
+	out_be32(&priv->regs[num - 1].gtccr, 0);
+	out_be32(&priv->regs[num - 1].gtbcr, rem_ticks);
+
+	return 0;
+}
+
+static struct mpic_timer *get_cascade_timer(struct timer_group_priv *priv,
+					u64 ticks)
+{
+	struct mpic_timer *allocated_timer;
+
+	/* Two cascade timers: Support the maximum time */
+	const u64 max_ticks = (u64)MAX_TICKS * (u64)MAX_TICKS_CASCADE;
+	int ret;
+
+	if (ticks > max_ticks)
+		return NULL;
+
+	/* detect idle timer */
+	allocated_timer = detect_idle_cascade_timer(priv);
+	if (!allocated_timer)
+		return NULL;
+
+	/* set ticks to timer */
+	ret = set_cascade_timer(priv, ticks, allocated_timer->num);
+	if (ret < 0)
+		return NULL;
+
+	return allocated_timer;
+}
+
+static struct mpic_timer *get_timer(const struct timeval *time)
+{
+	struct timer_group_priv *priv;
+	struct mpic_timer *timer;
+
+	u64 ticks;
+	unsigned int num;
+	unsigned int i;
+	unsigned long flags;
+	int ret;
+
+	list_for_each_entry(priv, &timer_group_list, node) {
+		ret = convert_time_to_ticks(priv, time, &ticks);
+		if (ret < 0)
+			return NULL;
+
+		if (ticks > MAX_TICKS) {
+			if (!(priv->flags & FSL_GLOBAL_TIMER))
+				return NULL;
+
+			timer = get_cascade_timer(priv, ticks);
+			if (!timer)
+				continue;
+			else
+				return timer;
+		}
+
+		for (i = 0; i < TIMERS_PER_GROUP; i++) {
+			/* one timer: Reverse allocation */
+			num = TIMERS_PER_GROUP - 1 - i;
+			spin_lock_irqsave(&priv->lock, flags);
+			if (priv->idle & (1 << i)) {
+				/* set timer busy */
+				priv->idle &= ~(1 << i);
+				/* set ticks & stop timer */
+				out_be32(&priv->regs[num].gtbcr,
+					ticks | TIMER_STOP);
+				out_be32(&priv->regs[num].gtccr, 0);
+				priv->timer[num].cascade_handle = NULL;
+				spin_unlock_irqrestore(&priv->lock, flags);
+				return &priv->timer[num];
+			}
+			spin_unlock_irqrestore(&priv->lock, flags);
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * mpic_start_timer - start hardware timer
+ * @handle: the timer to be started.
+ *
+ * It will do ->fn(->dev) callback from the hardware interrupt at
+ * the ->timeval point in the future.
+ */
+void mpic_start_timer(struct mpic_timer *handle)
+{
+	struct timer_group_priv *priv = container_of(handle,
+			struct timer_group_priv, timer[handle->num]);
+
+	clrbits32(&priv->regs[handle->num].gtbcr, TIMER_STOP);
+}
+EXPORT_SYMBOL(mpic_start_timer);
+
+/**
+ * mpic_stop_timer - stop hardware timer
+ * @handle: the timer to be stoped
+ *
+ * The timer periodically generates an interrupt. Unless user stops the timer.
+ */
+void mpic_stop_timer(struct mpic_timer *handle)
+{
+	struct timer_group_priv *priv = container_of(handle,
+			struct timer_group_priv, timer[handle->num]);
+	struct cascade_priv *casc_priv;
+
+	setbits32(&priv->regs[handle->num].gtbcr, TIMER_STOP);
+
+	casc_priv = priv->timer[handle->num].cascade_handle;
+	if (casc_priv) {
+		out_be32(&priv->regs[handle->num].gtccr, 0);
+		out_be32(&priv->regs[handle->num - 1].gtccr, 0);
+	} else {
+		out_be32(&priv->regs[handle->num].gtccr, 0);
+	}
+}
+EXPORT_SYMBOL(mpic_stop_timer);
+
+/**
+ * mpic_get_remain_time - get timer time
+ * @handle: the timer to be selected.
+ * @time: time for timer
+ *
+ * Query timer remaining time.
+ */
+void mpic_get_remain_time(struct mpic_timer *handle, struct timeval *time)
+{
+	struct timer_group_priv *priv = container_of(handle,
+			struct timer_group_priv, timer[handle->num]);
+	struct cascade_priv *casc_priv;
+
+	u64 ticks;
+	u32 tmp_ticks;
+
+	casc_priv = priv->timer[handle->num].cascade_handle;
+	if (casc_priv) {
+		tmp_ticks = in_be32(&priv->regs[handle->num].gtccr);
+		ticks = ((u64)tmp_ticks & UINT_MAX) * (u64)MAX_TICKS_CASCADE;
+		tmp_ticks = in_be32(&priv->regs[handle->num - 1].gtccr);
+		ticks += tmp_ticks;
+	} else {
+		ticks = in_be32(&priv->regs[handle->num].gtccr);
+	}
+
+	convert_ticks_to_time(priv, ticks, time);
+}
+EXPORT_SYMBOL(mpic_get_remain_time);
+
+/**
+ * mpic_free_timer - free hardware timer
+ * @handle: the timer to be removed.
+ *
+ * Free the timer.
+ *
+ * Note: can not be used in interrupt context.
+ */
+void mpic_free_timer(struct mpic_timer *handle)
+{
+	struct timer_group_priv *priv = container_of(handle,
+			struct timer_group_priv, timer[handle->num]);
+
+	struct cascade_priv *casc_priv;
+	unsigned long flags;
+
+	mpic_stop_timer(handle);
+
+	casc_priv = priv->timer[handle->num].cascade_handle;
+
+	free_irq(priv->timer[handle->num].irq, priv->timer[handle->num].dev);
+
+	spin_lock_irqsave(&priv->lock, flags);
+	if (casc_priv) {
+		u32 tcr;
+		tcr = casc_priv->tcr_value | (casc_priv->tcr_value <<
+					MPIC_TIMER_TCR_ROVR_OFFSET);
+		clrbits32(priv->group_tcr, tcr);
+		priv->idle |= casc_priv->cascade_map;
+		priv->timer[handle->num].cascade_handle = NULL;
+	} else {
+		priv->idle |= TIMER_OFFSET(handle->num);
+	}
+	spin_unlock_irqrestore(&priv->lock, flags);
+}
+EXPORT_SYMBOL(mpic_free_timer);
+
+/**
+ * mpic_request_timer - get a hardware timer
+ * @fn: interrupt handler function
+ * @dev: callback function of the data
+ * @time: time for timer
+ *
+ * This executes the "request_irq", returning NULL
+ * else "handle" on success.
+ */
+struct mpic_timer *mpic_request_timer(irq_handler_t fn, void *dev,
+					const struct timeval *time)
+{
+	struct mpic_timer *allocated_timer;
+	int ret;
+
+	if (list_empty(&timer_group_list))
+		return NULL;
+
+	if (!(time->tv_sec + time->tv_usec) ||
+			time->tv_sec < 0 || time->tv_usec < 0)
+		return NULL;
+
+	if (time->tv_usec > ONE_SECOND)
+		return NULL;
+
+	allocated_timer = get_timer(time);
+	if (!allocated_timer)
+		return NULL;
+
+	ret = request_irq(allocated_timer->irq, fn,
+			IRQF_TRIGGER_LOW, "global-timer", dev);
+	if (ret) {
+		mpic_free_timer(allocated_timer);
+		return NULL;
+	}
+
+	allocated_timer->dev = dev;
+
+	return allocated_timer;
+}
+EXPORT_SYMBOL(mpic_request_timer);
+
+static int timer_group_get_freq(struct device_node *np,
+			struct timer_group_priv *priv)
+{
+	if (priv->flags & FSL_GLOBAL_TIMER) {
+		struct device_node *dn;
+
+		dn = of_find_compatible_node(NULL, NULL, "fsl,mpic");
+		if (dn) {
+			of_property_read_u32(dn, "clock-frequency",
+					&priv->timerfreq);
+			of_node_put(dn);
+		}
+	}
+
+	if (priv->timerfreq <= 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int timer_group_get_irq(struct device_node *np,
+		struct timer_group_priv *priv)
+{
+	const u32 all_timer[] = { 0, TIMERS_PER_GROUP };
+	const u32 *p;
+	u32 offset;
+	u32 count;
+
+	unsigned int i;
+	unsigned int j;
+	unsigned int irq_index = 0;
+	unsigned int irq;
+	int len;
+
+	p = of_get_property(np, "fsl,available-ranges", &len);
+	if (p && len % (2 * sizeof(u32)) != 0) {
+		pr_err("%s: malformed available-ranges property.\n",
+				np->full_name);
+		return -EINVAL;
+	}
+
+	if (!p) {
+		p = all_timer;
+		len = sizeof(all_timer);
+	}
+
+	len /= 2 * sizeof(u32);
+
+	for (i = 0; i < len; i++) {
+		offset = p[i * 2];
+		count = p[i * 2 + 1];
+		for (j = 0; j < count; j++) {
+			irq = irq_of_parse_and_map(np, irq_index);
+			if (!irq) {
+				pr_err("%s: irq parse and map failed.\n",
+						np->full_name);
+				return -EINVAL;
+			}
+
+			/* Set timer idle */
+			priv->idle |= TIMER_OFFSET((offset + j));
+			priv->timer[offset + j].irq = irq;
+			priv->timer[offset + j].num = offset + j;
+			irq_index++;
+		}
+	}
+
+	return 0;
+}
+
+static void timer_group_init(struct device_node *np)
+{
+	struct timer_group_priv *priv;
+	unsigned int i = 0;
+	int ret;
+
+	priv = kzalloc(sizeof(struct timer_group_priv), GFP_KERNEL);
+	if (!priv) {
+		pr_err("%s: cannot allocate memory for group.\n",
+				np->full_name);
+		return;
+	}
+
+	if (of_device_is_compatible(np, "fsl,mpic-global-timer"))
+		priv->flags |= FSL_GLOBAL_TIMER;
+
+	priv->regs = of_iomap(np, i++);
+	if (!priv->regs) {
+		pr_err("%s: cannot ioremap timer register address.\n",
+				np->full_name);
+		goto out;
+	}
+
+	if (priv->flags & FSL_GLOBAL_TIMER) {
+		priv->group_tcr = of_iomap(np, i++);
+		if (!priv->group_tcr) {
+			pr_err("%s: cannot ioremap tcr address.\n",
+					np->full_name);
+			goto out;
+		}
+	}
+
+	ret = timer_group_get_freq(np, priv);
+	if (ret < 0) {
+		pr_err("%s: cannot get timer frequency.\n", np->full_name);
+		goto out;
+	}
+
+	ret = timer_group_get_irq(np, priv);
+	if (ret < 0) {
+		pr_err("%s: cannot get timer irqs.\n", np->full_name);
+		goto out;
+	}
+
+	spin_lock_init(&priv->lock);
+
+	/* Init FSL timer hardware */
+	if (priv->flags & FSL_GLOBAL_TIMER)
+		setbits32(priv->group_tcr, MPIC_TIMER_TCR_CLKDIV_64);
+
+	list_add_tail(&priv->node, &timer_group_list);
+
+	return;
+
+out:
+	if (priv->regs)
+		iounmap(priv->regs);
+
+	if (priv->group_tcr)
+		iounmap(priv->group_tcr);
+
+	kfree(priv);
+}
+
+static void mpic_timer_resume(void)
+{
+	struct timer_group_priv *priv;
+
+	list_for_each_entry(priv, &timer_group_list, node) {
+		/* Init FSL timer hardware */
+		if (priv->flags & FSL_GLOBAL_TIMER)
+			setbits32(priv->group_tcr, MPIC_TIMER_TCR_CLKDIV_64);
+	}
+}
+
+static const struct of_device_id mpic_timer_ids[] = {
+	{ .compatible = "fsl,mpic-global-timer", },
+	{},
+};
+
+static struct syscore_ops mpic_timer_syscore_ops = {
+	.resume = mpic_timer_resume,
+};
+
+static int __init mpic_timer_init(void)
+{
+	struct device_node *np = NULL;
+
+	for_each_matching_node(np, mpic_timer_ids)
+		timer_group_init(np);
+
+	register_syscore_ops(&mpic_timer_syscore_ops);
+
+	if (list_empty(&timer_group_list))
+		return -ENODEV;
+
+	return 0;
+}
+subsys_initcall(mpic_timer_init);