Subject: [PATCH] ARM: OMAP5/DRA7: realtime_counter: Configure CNTFRQ register

From: [email-masked] (Sricharan R)
Date: Wed, 18 Sep 2013 19:21:19 +0530

On Wednesday 18 September 2013 07:19 PM, Santosh Shilimkar wrote:
> On Wednesday 18 September 2013 09:44 AM, Sricharan R wrote:
>> On Wednesday 18 September 2013 07:01 PM, Santosh Shilimkar wrote:
>>> On Wednesday 18 September 2013 07:23 AM, Sricharan R wrote:
>>>> The realtime counter called master counter, produces the count
>>>> used by the private timer peripherals in the MPU_CLUSTER. The
>>>> CNTFRQ per cpu register is used to denote the frequency of the counter.
>>>> Currently the frequency value is passed from the
>>>> DT file, but this is not scalable when we have other non-DT guest
>>>> OS. This register must be set to the right value by the
>>>> host OS, as this will be propagated to the guests as well.
>>>>
>>> Its not host OS but ROM code/secure code. Host OS is not
>>> ideal place to set it up.
>>  ok, so you are suggesting to re word this right ?
>>>> More discussions and the reason for adding this in a non-DT
>>>> way can be seen from below.
>>>> http://www.mail-archive.com/linux-omap at vger.kernel.org/msg93832.html
>>>>
>>>> So configuring this secure register for all the cpus here.
>>>>
>>>> Cc: Santosh Shilimkar <[email-masked]>
>>>> Cc: Nishanth Menon <[email-masked]>
>>>> Cc: Rajendra Nayak <[email-masked]>
>>>> Cc: Marc Zyngier <[email-masked]>
>>>> Cc: Mark Rutland <[email-masked]>
>>>> Cc: Tony Lindgren <[email-masked]>
>>>> Signed-off-by: Sricharan R <[email-masked]>
>>>> ---
>>>>  arch/arm/mach-omap2/omap-secure.h |    2 ++
>>>>  arch/arm/mach-omap2/omap-smp.c    |    9 +++++++++
>>>>  arch/arm/mach-omap2/timer.c       |    6 ++++++
>>>>  3 files changed, 17 insertions(+)
>>>>
>>>> diff --git a/arch/arm/mach-omap2/omap-secure.h b/arch/arm/mach-omap2/omap-secure.h
>>>> index a171a5a..4de9a00 100644
>>>> --- a/arch/arm/mach-omap2/omap-secure.h
>>>> +++ b/arch/arm/mach-omap2/omap-secure.h
>>>> @@ -51,6 +51,8 @@
>>>>  
>>>>  #define OMAP5_MON_AMBA_IF_INDEX		0x108
>>>>  
>>>> +#define OMAP5_DRA7_MON_SET_CNTFRQ_INDEX	0x109
>>>> +
>>> Nice. Looks like OMAP5 ES2.0 addition which I missed.
>>>
>>>>  /* Secure PPA(Primary Protected Application) APIs */
>>>>  #define OMAP4_PPA_L2_POR_INDEX		0x23
>>>>  #define OMAP4_PPA_CPU_ACTRL_SMP_INDEX	0x25
>>>> diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
>>>> index 98a1146..00873b4 100644
>>>> --- a/arch/arm/mach-omap2/omap-smp.c
>>>> +++ b/arch/arm/mach-omap2/omap-smp.c
>>>> @@ -41,6 +41,8 @@
>>>>  
>>>>  u16 pm44xx_errata;
>>>>  
>>>> +extern unsigned long arch_timer_freq;
>>>> +
>>>>  /* SCU base address */
>>>>  static void __iomem *scu_base;
>>>>  
>>>> @@ -66,6 +68,13 @@ static void __cpuinit omap4_secondary_init(unsigned int cpu)
>>>>  							4, 0, 0, 0, 0, 0);
>>>>  
>>>>  	/*
>>>> +	 * Configure the CNTFRQ register for the secondary cpu's which
>>>> +	 * indicates the frequency of the cpu local timers.
>>>> +	 */
>>>> +	if (soc_is_omap54xx() || soc_is_dra7xx())
>>> CNTFREQ programming was not supported on OMAP5 ES1.0 and that was one
>>> of the reason this parameter came into picture. So you need to skip
>>> the ES1.0 here. 
>>  We do not intend to support ES1.0 right ? . ok then id.c needs to be
>>  cleaned up to remove ES1.0 traces.
> yes. With clean-up ES1.0, this can stay as is.
>
>>>> +		omap_smc1(OMAP5_DRA7_MON_SET_CNTFRQ_INDEX, arch_timer_freq);
>>>> +
>>>> +	/*
>>>>  	 * Synchronise with the boot thread.
>>>>  	 */
>>>>  	spin_lock(&boot_lock);
>>>> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
>>>> index fd9238d..2c499f3 100644
>>>> --- a/arch/arm/mach-omap2/timer.c
>>>> +++ b/arch/arm/mach-omap2/timer.c
>>>> @@ -55,6 +55,7 @@
>>>>  #include "soc.h"
>>>>  #include "common.h"
>>>>  #include "powerdomain.h"
>>>> +#include "omap-secure.h"
>>>>  
>>>>  #define REALTIME_COUNTER_BASE				0x48243200
>>>>  #define INCREMENTER_NUMERATOR_OFFSET			0x10
>>>> @@ -65,6 +66,7 @@
>>>>  
>>>>  static struct omap_dm_timer clkev;
>>>>  static struct clock_event_device clockevent_gpt;
>>>> +unsigned long arch_timer_freq;
>>>>  
>>>>  static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
>>>>  {
>>>> @@ -546,7 +548,11 @@ static void __init realtime_counter_init(void)
>>>>  	reg |= den;
>>>>  	__raw_writel(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);
>>>>  
>>>> +	arch_timer_freq = (rate / den) * num;
>>>> +
>>>>  	iounmap(base);
>>>> +
>>>> +	omap_smc1(OMAP5_DRA7_MON_SET_CNTFRQ_INDEX, arch_timer_freq);
>>> Few problems with this approach..
>>>
>>> 1. CNTFREQ needs to be programmed on all CPUs. Even though arch-timer
>>> code uses boot-cpu now thats not safe for guest which can start on
>>> secondary CPUs. So please update this in secondary boot path as well.
>> The patch is doing this for secondary cpu's as well in the
>> call back  omap4_secondary_init.
>>
> NM just pointed out this off-list.
>
>  
>>> 2. When you power cycle CPU, you will loose the value of this register
>>> so you need to reprogram them on every CPU power up. Both DRA and OMAP5
>>> doesn't support that part yet but do remember to patch that when
>>> such support gets added.
>>  oh ok. did not realize this. Will add the change for this then.
> Since PM isn't supported for now, the patch looks alright with ES1.0
> support gets dropped. Just fix the change-log.
>
> Feel free to add my ack on updated version.
 Thanks. Will repost with the updated log and ack.

Regards,
 Sricharan