Subject: [PATCH 14/15] ARM: OMAP4+: CPUidle: Add OMAP5 idle driver support

From: [email-masked] (Nishanth Menon)
Date: Mon, 4 Mar 2013 12:48:46 -0600

On 12:17-20130302, Santosh Shilimkar wrote:
> On Saturday 02 March 2013 05:55 AM, Nishanth Menon wrote:
> > On 17:41-20130301, Santosh Shilimkar wrote:
> >> The OMAP5 idle driver can re-use OMAP4 CPUidle driver implementation thanks
> >> to compatible MPUSS design.
> >>
> >> Though unlike OMAP4, on OMAP5 devices, MPUSS CSWR (Close Switch Retention)
> >> power states can be achieved with respective power states on CPU0 and CPU1
> >> power domain. This mode was broken on OMAP4 devices because of hardware
> >> limitation. Also there is no CPU low power entry order requirement like
> >> master CPU etc for CSWR C-state, which is icing on the cake. Code makes
> >> use of voting scheme for cluster low power state to support MPUSS CSWR
> >> C-state.
> >>
> >> Supported OMAP5 CPUidle C-states:
> >>         C1 - CPU0 ON(WFI) + CPU1 ON(WFI) + MPUSS ON
> >>         C2 - CPU0 CSWR + CPU1 CSWR + MPUSS CSWR
> >>         C3 - CPU0 OFF + CPU1 Force OFF + MPUSS OSWR
> >  think you meant CPU1 OFF?
> Yes.
> >>
> >> Signed-off-by: Santosh Shilimkar <[email-masked]>
> >> ---
> >>  arch/arm/mach-omap2/Kconfig                        |    1 +
> >>  arch/arm/mach-omap2/Makefile                       |    4 +-
> >>  .../{cpuidle44xx.c => cpuidle_omap4plus.c}         |  103 +++++++++++++++++++-
> >>  arch/arm/mach-omap2/omap-mpuss-lowpower.c          |    7 +-
> >>  arch/arm/mach-omap2/pm_omap4plus.c                 |    2 +-
> >>  5 files changed, 110 insertions(+), 7 deletions(-)
> >>  rename arch/arm/mach-omap2/{cpuidle44xx.c => cpuidle_omap4plus.c} (70%)
> >>
> >> diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
> >> index 41b581f..2df91dc 100644
> >> --- a/arch/arm/mach-omap2/Kconfig
> >> +++ b/arch/arm/mach-omap2/Kconfig
> >> @@ -82,6 +82,7 @@ config SOC_OMAP5
> >>  	select CPU_V7
> >>  	select HAVE_SMP
> >>  	select COMMON_CLK
> >> +	select ARCH_NEEDS_CPU_IDLE_COUPLED
> >>  
> >>  comment "OMAP Core Type"
> >>  	depends on ARCH_OMAP2
> >> diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
> >> index 7c3c6b6..f6ff88f 100644
> >> --- a/arch/arm/mach-omap2/Makefile
> >> +++ b/arch/arm/mach-omap2/Makefile
> >> @@ -97,8 +97,10 @@ endif
> >>  endif
> >>  
> >>  ifeq ($(CONFIG_CPU_IDLE),y)
> >> +omap4plus-common-idle			= cpuidle_omap4plus.o
> >>  obj-$(CONFIG_ARCH_OMAP3)                += cpuidle34xx.o
> >> -obj-$(CONFIG_ARCH_OMAP4)                += cpuidle44xx.o
> >> +obj-$(CONFIG_ARCH_OMAP4)		+= $(omap4plus-common-idle)
> >> +obj-$(CONFIG_SOC_OMAP5)			+= $(omap4plus-common-idle)
> > nit pick: simpler to use cpuidle_omap4plus.o or do we expect more objs -
> > like moving the idle_data to DTS or so?
> No I haven't that on that path. Easy from maintenance point of view. common
> object and a label. Thats all.
> 
> >>  endif
> >>  
> >>  # PRCM
> >> diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle_omap4plus.c
> >> similarity index 70%
> >> rename from arch/arm/mach-omap2/cpuidle44xx.c
> >> rename to arch/arm/mach-omap2/cpuidle_omap4plus.c
> >> index 23286c1..8681fa6 100644
> >> --- a/arch/arm/mach-omap2/cpuidle44xx.c
> >> +++ b/arch/arm/mach-omap2/cpuidle_omap4plus.c
> >> @@ -29,6 +29,7 @@ struct idle_statedata {
> >>  	u32 cpu_state;
> >>  	u32 mpu_logic_state;
> >>  	u32 mpu_state;
> >> +	u32 mpu_state_vote;
> >>  };
> >>  
> >>  static struct idle_statedata omap4_idle_data[] = {
> >> @@ -49,17 +50,36 @@ static struct idle_statedata omap4_idle_data[] = {
> >>  	},
> >>  };
> >>  
> >> +static struct idle_statedata omap5_idle_data[] = {
> >> +	{
> >> +		.cpu_state = PWRDM_POWER_ON,
> >> +		.mpu_state = PWRDM_POWER_ON,
> >> +		.mpu_logic_state = PWRDM_POWER_RET,
> >> +	},
> >> +	{
> >> +		.cpu_state = PWRDM_POWER_RET,
> > CSWR I assume -> Documenting it helps? or we should introdce
> > cpu_logic_state to be explicit?
> Its is documented just below the table(desc). No need to add useless
> cpu_logic_state variable. This is part of the big C-state table.
> 
> 
> >
> [..]
> >>  /*
> >>   * For each cpu, setup the broadcast timer because local timers
> >>   * stops for the states above C1.
> >> @@ -209,6 +262,43 @@ static struct cpuidle_driver omap4_idle_driver = {
> >>  	.safe_state_index = 0,
> >>  };
> >>  
> >> +static struct cpuidle_driver omap5_idle_driver = {
> >> +	.name				= "omap5_idle",
> >> +	.owner				= THIS_MODULE,
> >> +	.en_core_tk_irqen		= 1,
> >> +	.states = {
> >> +		{
> >> +			/* C1 - CPU0 ON + CPU1 ON + MPU ON */
> > we could move these to .desc
> That will be too much ... also above just for refence and understanding
> otherwise, CPU state is per CPU so we can't say CPU0 =x, and CPU1 = y in
> CPU0 C-state. I like the way .desc is today and would want to keep it that
> way.
imagine having kernel definitions change on a wide variety of customer
platforms - it is easy for us in customer support team to dump the
descriptions off the sysfs entries to know precisely what they would
probably be using. IMHO, making desc as an generated string is nice,
failing which either documenting it OR expanding idle_statedata to mean
the exact h/w state configured is the best option.
> 
> >> +			.exit_latency = 2 + 2,
> >> +			.target_residency = 5,
> > the obvious question on how these latencies were arrived at..
> Based on the internal measurements done only considering MPUSS
> C-state latencies.
OK.
> 
> 
> >> @@ -243,8 +333,13 @@ int __init omap4_idle_init(void)
> >>  #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
> >>  		dev->coupled_cpus = *cpu_online_mask;
> >>  #endif
> >> -		state_ptr = &omap4_idle_data[0];
> >> -		cpuidle_register_driver(&omap4_idle_driver);
> >> +		if (cpu_is_omap44xx()) {
> >> +			state_ptr = &omap4_idle_data[0];
> >> +			cpuidle_register_driver(&omap4_idle_driver);
> >> +		} else if (soc_is_omap54xx()) {
> >> +			state_ptr = &omap5_idle_data[0];
> >> +			cpuidle_register_driver(&omap5_idle_driver);
> >> +		}
> > we'd be doing cpuidle_register_driver twice since it is within the
> > for_each_cpu loop - we dont want to do that.
> Yep. I will move that out of the loop though second registration is just
> a nop.
Thanks. that said, I think it is best to register the driver *after* we
have done the state population (we do not want cpuidle driver to manage
CPU0 while we are getting CPU1 state vars ready)
> >>  
> >>  		if (cpuidle_register_device(dev)) {
> >>  			pr_err("%s: CPUidle register failed\n", __func__);
> >> diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> >> index 5d32444..0ccb76e 100644
> >> --- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> >> +++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> >> @@ -87,7 +87,7 @@ extern void omap5_cpu_resume(void);
> >>  static DEFINE_PER_CPU(struct omap4_cpu_pm_info, omap4_pm_info);
> >>  static struct powerdomain *mpuss_pd;
> >>  static void __iomem *sar_base;
> >> -static u32 cpu_context_offset;
> >> +static u32 cpu_context_offset, cpu_cswr_supported;
> >>  
> >>  static int default_finish_suspend(unsigned long cpu_state)
> >>  {
> >> @@ -265,6 +265,10 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
> >>  		save_state = 1;
> >>  		break;
> >>  	case PWRDM_POWER_RET:
> >> +		if (cpu_cswr_supported) {
> >> +			save_state = 0;
> >> +			break;
> >> +		}
> > ok, I guess this is the best we can do under the current circumstance
> > where PWRDM_POWER_RET means either CSWR or OSWR!
> The switch is for CPUx power states and hence there is no question of
> OSWR. CPUx OSWR = CPUx OFF hence CPUx OSWR isn't supported. This has been
> known from OMAP4 days. CPU RET isn't supported on OMAP4 and hence
> that variable is added.
OK.

-- 
Regards,
Nishanth Menon