Re: [PATCH 18/19] omap3630+: sr: add support for class 1.5

Menon, Nishanth
2011-03-01T10:18:07Z

On Tue, Mar 1, 2011 at 15:23, Gulati, Shweta <shweta.gulati@ti.com> wrote:
>
> Hi,
>
> On Sat, Feb 19, 2011 at 5:31 PM, Nishanth Menon <nm@ti.com> wrote:
> > Traditional SmartReflex AVS(Automatic Voltage Scaling) classes are:
> > * Class 0 - Product test calibration
> >        Silicon is calibration at production floor and fused with voltages
> >        for each OPP
> > * Class 1 - Boot time calibration
> >        Silicon is calibrated once at boot time and voltages are stored for
> >        the lifetime of operation.
> > * Class 2 - continuous s/w calibration
> >        SR module notifies s/w for any change in the system which is desired
> >        and the s/w makes runtime decisions in terms of setting the voltage,
> >        this mechanism could be used in the system which does not have PMIC
> >        capable of SR without using the voltage controller and voltage
> >        processor blocks.
> > * Class 3 - continuous h/w calibration
> >        SR module is switch on after reaching a voltage level and SR
> >        continuously monitors the system and makes runtime adjustments without
> >        s/w involvement.
> >
> > OMAP3430 has used SmartReflex AVS and with a a PMIC which understands the SR
> > protocol, Class 3 has been used. With OMAP3630 onwards, a new SmartReflex AVS
> > class of operation Class 1.5 was introduced.
> > * Class 1.5 - periodic s/w calibration
> >        This uses the h/w calibration loop and at the end of calibration
> >        stores the voltages to be used run time, periodic recalibration is
> >        performed as well.
> >
> > The operational mode is describes as the following:
> > * SmartReflex AVS h/w calibration loop is essential to identify the optimal
> >        voltage for a given OPP.
> > * Once this optimal voltage is detected, SmartReflex AVS loop is disabled in
> >        class 1.5 mode of operation.
> > * Until there is a need for a recalibration, any further transition to an OPP
> >        voltage which is calibrated can use the calibrated voltage and does not
> >        require enabling the SR AVS h/w loop.
> > * On a periodic basis (recommendation being once approximately every 24 hours),
> >        software is expected to perform a recalibration to find a new optimal
> >        voltage which is compensated for device aging.
> >        - For performing this recalibration, the start voltage does not need to
> >        be the nominal voltage anymore. instead, the system can start with a
> >        voltage which is 50mV higher than the previously calibrated voltage to
> >        identify the new optimal voltage as the aging factor within a period of
> >        1 day is not going to be anywhere close to 50mV.
> >        - This "new starting point" for recalibration is called a dynamic
> >        nominal voltage for that voltage point.
> > In short, with the introduction of SmartReflex class 1.5, there are three new
> > voltages possible in a system's dvfs transition:
> > * Nominal Voltage - The maximum voltage needed for a worst possible device
> >        in the worst possible conditions. This is the voltage we choose as
> >        the starting point for the h/w loop to optimize for the first time
> >        calibration on system bootup.
> > * Dynamic Nominal Voltage - Worst case voltage for a specific device in
> >        considering the system aging on the worst process device.
> > * Calibrated Voltage - Best voltage for the current device at a given point
> >        of time.
> >
> > In terms of the implementation, doing calibration involves waiting for the
> > smartreflex h/w loop to settle down, and doing this as part of the dvfs flow
> > itself is to increase the latency of dvfs transition when there is a need to
> > calibrate that opp. instead, the calibration is performed "out of path" using
> > a workqueue statemachine. The workqueue waits for the system stabilization,
> > then enables VP interrupts to monitor for system instability interms of voltage
> > oscillations that are reported back to the system as interrupts, in case of
> > prolonged system oscillations, nominal voltage is chosen as a safe voltage and
> > this event is logged in the system log for developer debug and fixing.
> >
> > For the recalibration, a common workqueue for all domains is started at the
> > start of the class initialization and it resets the calibrated voltages
> > on a periodic basis. For distros that may choose not to do the recommended
> > periodic recalibration, instead choose to perform boot time calibration,
> > kconfig configuration option is provided to do so.
> >
> > TODO:
> > a) Cpuidle and suspend paths are not integrated with SmartReflex driver at
> >   this point.
> > b) Since the SR registers are accessed and controlled in parallel to DVFS
> >   some sort of mechanism is necessary to be introduced along with OMAP
> >   dvfs layer to ensure mutual exclusivity
> > c) Additional debug interfaces for vmin analysis for platform characterization
> >   and addition of system margin needs to be introduced from smartreflex
> >   perspective.
> >
> > This implementation also includes the following contributors:
> > Tony Lindgren for suggestion on using interrupt based mechanism instead of
> > polling to detect voltage oscillations.
> > Peter 'p2' De Schrijver for debating alternatives on recalibration mechanisms
> > Paul Walmsey, Eduardo Valentin, Ambresh K, Igor Dmitriev and quiet a few others
> > for patient review, testing and reporting of issues of a previous incarnation
> > of this implemenation. Last, but not the least, the TI H/w team in introducing
> > this new SR AVS class and patiently debating it's various facets.
> >
> > Cc: Ambresh K <ambresh@ti.com>
> > Cc: Eduardo Valentin <eduardo.valentin@nokia.com>
> > Cc: Igor Dmitriev <ext-dmitriev.igor@nokia.com>
> > Cc: Paul <paul@pwsan.com>
> > Cc: Peter 'p2' De Schrijver <Peter.De-Schrijver@nokia.com>
> > Cc: Tony Lindgren <tony@atomide.com>
> >
> > Signed-off-by: Nishanth Menon <nm@ti.com>
> > ---
> >  arch/arm/mach-omap2/Makefile                  |    1 +
> >  arch/arm/mach-omap2/smartreflex-class1p5.c    |  556 +++++++++++++++++++++++++
> >  arch/arm/mach-omap2/smartreflex-class3.c      |    4 +-
> >  arch/arm/mach-omap2/smartreflex.c             |   34 ++-
> >  arch/arm/mach-omap2/voltage.c                 |   69 +++
> >  arch/arm/plat-omap/Kconfig                    |   17 +
> >  arch/arm/plat-omap/include/plat/smartreflex.h |   13 +-
> >  arch/arm/plat-omap/include/plat/voltage.h     |   23 +-
> >  8 files changed, 709 insertions(+), 8 deletions(-)
> >  create mode 100644 arch/arm/mach-omap2/smartreflex-class1p5.c
> >
> > diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
> > index 1c0c2b0..1a82e6d 100644
> > --- a/arch/arm/mach-omap2/Makefile
> > +++ b/arch/arm/mach-omap2/Makefile
> > @@ -66,6 +66,7 @@ obj-$(CONFIG_ARCH_OMAP4)              += pm44xx.o voltage.o pm_bus.o
> >  obj-$(CONFIG_PM_DEBUG)                 += pm-debug.o
> >  obj-$(CONFIG_OMAP_SMARTREFLEX)          += sr_device.o smartreflex.o
> >  obj-$(CONFIG_OMAP_SMARTREFLEX_CLASS3)  += smartreflex-class3.o
> > +obj-$(CONFIG_OMAP_SMARTREFLEX_CLASS1P5)        += smartreflex-class1p5.o
> >
> >  AFLAGS_sleep24xx.o                     :=-Wa,-march=armv6
> >  AFLAGS_sleep34xx.o                     :=-Wa,-march=armv7-a
> > diff --git a/arch/arm/mach-omap2/smartreflex-class1p5.c b/arch/arm/mach-omap2/smartreflex-class1p5.c
> > new file mode 100644
> > index 0000000..832f10b
> > --- /dev/null
> > +++ b/arch/arm/mach-omap2/smartreflex-class1p5.c
> > @@ -0,0 +1,556 @@
> > +/*
> > + * Smart reflex Class 1.5 specific implementations
> > + *
> > + * Copyright (C) 2010-2011 Texas Instruments, Inc.
> > + * Nishanth Menon <nm@ti.com>
> > + *
> > + * Smart reflex class 1.5 is also called periodic SW Calibration
> > + * Some of the highlights are as follows:
> > + * – Host CPU triggers OPP calibration when transitioning to non calibrated
> > + *   OPP
> > + * – SR-AVS + VP modules are used to perform calibration
> > + * – Once completed, the SmartReflex-AVS module can be disabled
> > + * – Enables savings based on process, supply DC accuracy and aging
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +#include <linux/kernel.h>
> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/fs.h>
> > +#include <linux/string.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/kobject.h>
> > +#include <linux/workqueue.h>
> > +#include <linux/opp.h>
> > +
> > +#include <plat/smartreflex.h>
> > +#include <plat/voltage.h>
> > +
> > +#define MAX_VDDS 3
> > +#define SR1P5_SAMPLING_DELAY_MS        1
> > +#define SR1P5_STABLE_SAMPLES   5
> > +#define SR1P5_MAX_TRIGGERS     5
> > +
> > +/*
> > + * we expect events in 10uS, if we dont get 2wice times as much,
> > + * we could kind of ignore this as a missed event.
> > + */
> > +#define MAX_CHECK_VPTRANS_US   20
> > +
> > +/**
> > + * struct sr_class1p5_work_data - data meant to be used by calibration work
> > + * @work:      calibration work
> > + * @voltdm:            voltage domain for which we are triggering
> > + * @vdata:     voltage data we are calibrating
> > + * @num_calib_triggers:        number of triggers from calibration loop
> > + * @num_osc_samples:   number of samples collected by isr
> > + * @work_active:       have we scheduled a work item?
> > + */
> > +struct sr_class1p5_work_data {
> > +       struct delayed_work work;
> > +       struct voltagedomain *voltdm;
> > +       struct omap_volt_data *vdata;
> > +       u8 num_calib_triggers;
> > +       u8 num_osc_samples;
> > +       bool work_active;
> > +};
> > +
> > +#if CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY
> > +/* recal_work: recalibration calibration work */
> > +static struct delayed_work recal_work;
> > +#endif
> > +
> > +/**
> > + * struct sr_class1p5_data - private data for class 1p5
> > + * @work_data:         work item data per voltage domain
> > + */
> > +struct sr_class1p5_data {
> > +       struct sr_class1p5_work_data work_data[MAX_VDDS];
> > +};
> > +
> > +static void sr_class1p5_reset_calib(struct voltagedomain *voltdm, bool reset,
> > +                                   bool recal);
> > +
> > +/* our instance of class 1p5 private data */
> > +static struct sr_class1p5_data class_1p5_data;
> > +
> > +static struct sr_class1p5_work_data *get_sr1p5_work(struct voltagedomain
> > +                                                   *voltdm)
> > +{
> > +       int idx;
> > +       for (idx = 0; idx < MAX_VDDS; idx++) {
> > +               if (class_1p5_data.work_data[idx].voltdm && !strcmp
> > +                   (class_1p5_data.work_data[idx].voltdm->name, voltdm->name))
> > +                       return &class_1p5_data.work_data[idx];
> > +       }
> > +       return ERR_PTR(-ENODATA);
> > +}
> > +
> > +/**
> > + * sr_class1p5_notify() - isr notifier for status events
> > + * @voltdm:    voltage domain for which we were triggered
> > + * @status:    notifier event to use
> > + *
> > + * This basically collects data for the work to use.
> > + */
> > +static int sr_class1p5_notify(struct voltagedomain *voltdm, u32 status)
> > +{
> > +       struct sr_class1p5_work_data *work_data;
> > +       int idx = 0;
> > +       work_data = get_sr1p5_work(voltdm);
> > +
> > +       if (unlikely(!work_data)) {
> > +               pr_err("%s:%s no work data!!\n", __func__, voltdm->name);
> > +               return -EINVAL;
> > +       }
> > +
> > +       /* Wait for transdone so that we know the voltage to read */
> > +       do {
> > +               if (omap_vp_is_transdone(voltdm))
> > +                       break;
> > +               idx++;
> > +               /* get some constant delay */
> > +               udelay(1);
> > +       } while (idx < MAX_CHECK_VPTRANS_US);
> > +
> > +       /*
> > +        * If we timeout, we still read the data,
> > +        * if we are oscillating+irq latencies are too high, we could
> > +        * have scenarios where we miss transdone event. since
> > +        * we waited long enough, it is still safe to read the voltage
> > +        * as we would have waited long enough - still flag it..
> > +        */
> > +       if (idx >= MAX_CHECK_VPTRANS_US)
> > +               pr_warning("%s: timed out waiting for transdone!!\n", __func__);
> > +
> > +       omap_vp_clear_transdone(voltdm);
> > +
> > +       idx = (work_data->num_osc_samples) % SR1P5_STABLE_SAMPLES;
> > +       work_data->num_osc_samples++;
> > +
> > +       return 0;
> > +}
> > +
> > +/**
> > + * do_calibrate() - work which actually does the calibration
> > + * @work: pointer to the work
> > + *
> > + * calibration routine uses the following logic:
> > + * on the first trigger, we start the isr to collect sr voltages
> > + * wait for stabilization delay (reschdule self instead of sleeping)
> > + * after the delay, see if we collected any isr events
> > + * if none, we have calibrated voltage.
> > + * if there are any, we retry untill we giveup.
> > + * on retry timeout, select a voltage to use as safe voltage.
> > + */
> > +static void do_calibrate(struct work_struct *work)
> > +{
> > +       struct sr_class1p5_work_data *work_data =
> > +           container_of(work, struct sr_class1p5_work_data, work.work);
> > +       unsigned long u_volt_safe = 0, u_volt_current = 0;
> > +       struct omap_volt_data *volt_data;
> > +       struct voltagedomain *voltdm;
> > +
> > +       if (unlikely(!work_data)) {
> > +               pr_err("%s: ooops.. null work_data?\n", __func__);
> > +               return;
> > +       }
> > +
> > +       /*
> > +        * TODO:Handle the case where we might have just been scheduled AND
> > +        * 1.5 disable was called. check and HOLD dvfs
> > +        */
> > +
> > +       voltdm = work_data->voltdm;
> > +       /*
> > +        * In the unlikely case that we did get through when unplanned,
> > +        * flag and return.
> > +        */
> > +       if (unlikely(!work_data->work_active)) {
> > +               pr_err("%s:%s unplanned work invocation!\n", __func__,
> > +                      voltdm->name);
> > +               /* TODO release the dvfs */
> > +               return;
> > +       }
> > +
> > +       work_data->num_calib_triggers++;
> > +       /* if we are triggered first time, we need to start isr to sample */
> > +       if (work_data->num_calib_triggers == 1)
> > +               goto start_sampling;
> > +
> > +       /* Stop isr from interrupting our measurements :) */
> > +       sr_notifier_control(voltdm, false);
> > +
> > +       volt_data = work_data->vdata;
> > +
> > +       /* if there are no samples captured.. SR is silent, aka stability! */
> > +       if (!work_data->num_osc_samples) {
> > +               u_volt_safe = omap_vp_get_curr_volt(voltdm);
> > +               u_volt_current = u_volt_safe;
> > +               goto done_calib;
> > +       }
> > +       if (work_data->num_calib_triggers == SR1P5_MAX_TRIGGERS) {
> > +               pr_warning("%s: %s recalib timeout!\n", __func__,
> > +                          work_data->voltdm->name);
> > +               goto oscillating_calib;
> > +       }
> > +
> > +       /* we have potential oscillations/first sample */
> > +start_sampling:
> > +       work_data->num_osc_samples = 0;
> > +       /* Clear pending events */
> > +       sr_notifier_control(voltdm, false);
> > +       /* Clear all transdones */
> > +       while (omap_vp_is_transdone(voltdm))
> > +               omap_vp_clear_transdone(voltdm);
> > +       /* trigger sampling */
> > +       sr_notifier_control(voltdm, true);
> > +       schedule_delayed_work(&work_data->work,
> > +                             msecs_to_jiffies(SR1P5_SAMPLING_DELAY_MS *
> > +                                              SR1P5_STABLE_SAMPLES));
> > +       /* TODO: release dvfs */
> > +       return;
> > +
> > +oscillating_calib:
> > +       /* Use the nominal voltage as the safe voltage */
> > +       u_volt_safe = volt_data->volt_nominal;
> > +       /* pick up current voltage to switch if needed */
> > +       u_volt_current = omap_vp_get_curr_volt(voltdm);
> > +
> > +       /* Fall through to close up common stuff */
> > +done_calib:
> > +       omap_vp_disable(voltdm);
> > +       sr_disable(voltdm);
> > +
> > +       volt_data->volt_calibrated = u_volt_safe;
> > +       /* Setup my dynamic voltage for the next calibration for this opp */
> > +       volt_data->volt_dynamic_nominal = omap_get_dyn_nominal(volt_data);
> > +
> > +       /*
> > +        * if the voltage we decided as safe is not the current voltage,
> > +        * switch
> > +        */
> > +       if (volt_data->volt_calibrated != u_volt_current) {
> > +               pr_debug("%s:%s reconfiguring to voltage %d\n",
> > +                        __func__, voltdm->name, volt_data->volt_calibrated);
> > +               omap_voltage_scale_vdd(voltdm, volt_data);
> > +       }
> > +
> > +       /*
> > +        * TODO: Setup my wakeup voltage to allow immediate going to OFF and
> > +        * on - Pending twl and voltage layer cleanups.
> > +        * This is necessary, as this is not done as part of regular
> > +        * Dvfs flow.
> > +        * vc_setup_on_voltage(voltdm, volt_data->volt_calibrated);
> > +        */
> > +       work_data->work_active = false;
> > +       /* TODO: release dvfs */
> > +}
> > +
> > +#if CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY
> > +/**
> > + * do_recalibrate() - work which actually does the calibration
> > + * @work: pointer to the work
> > + *
> > + * on a periodic basis, we come and reset our calibration setup
> > + * so that a recalibration of the OPPs take place. This takes
> > + * care of aging factor in the system.
> > + */
> > +static void do_recalibrate(struct work_struct *work)
> > +{
> > +       struct voltagedomain *voltdm;
> > +       int idx;
> > +       static struct sr_class1p5_work_data *work_data;
> > +
> > +       for (idx = 0; idx < MAX_VDDS; idx++) {
> > +               work_data = &class_1p5_data.work_data[idx];
> > +               voltdm = work_data->voltdm;
> > +               if (voltdm) {
> > +                       /* if sr is not enabled, we check later */
> > +                       if (!is_sr_enabled(voltdm))
> > +                               continue;
> > +                       /* TODO: Pause the dvfs transitions */
> > +                       /* if sr is not enabled, we check later */
> > +
> > +                       /* Reset and force a recalibration for current opp */
> > +                       sr_class1p5_reset_calib(voltdm, true, true);
> > +
> > +                       /* TODO: unpause DVFS transitions */
> > +               }
> > +       }
> > +       /* We come back again after time the usual delay */
> > +       schedule_delayed_work(&recal_work,
> > +             msecs_to_jiffies(CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY));
> > +}
> > +#endif /* CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY */
> > +
> > +/**
> > + * sr_class1p5_enable() - class 1.5 mode of enable
> > + * @voltdm:            voltage domain to enable SR for
> > + * @volt_data: voltdata to the voltage transition taking place
> > + *
> > + * when this gets called, we use the h/w loop to setup our voltages
> > + * to an calibrated voltage, detect any oscillations, recover from the same
> > + * and finally store the optimized voltage as the calibrated voltage in the
> > + * system
> > + */
> > +static int sr_class1p5_enable(struct voltagedomain *voltdm,
> > +                             struct omap_volt_data *volt_data)
> > +{
> > +       int r;
> > +       struct sr_class1p5_work_data *work_data;
> > +       /* if already calibrated, nothing to do here.. */
> > +       if (volt_data->volt_calibrated)
> > +               return 0;
> > +
> > +       work_data = get_sr1p5_work(voltdm);
> > +       if (unlikely(!work_data)) {
> > +               pr_err("%s: aieeee.. bad work data??\n", __func__);
> > +               return -EINVAL;
> > +       }
> > +
> > +       if (work_data->work_active)
> > +               return 0;
> > +
> > +       omap_vp_enable(voltdm);
> > +       r = sr_enable(voltdm, volt_data);
> > +       if (r) {
> > +               pr_err("%s: sr[%s] failed\n", __func__, voltdm->name);
> > +               omap_vp_disable(voltdm);
> > +               return r;
> > +       }
> > +       work_data->vdata = volt_data;
> > +       work_data->work_active = true;
> > +       work_data->num_calib_triggers = 0;
> > +       /* program the workqueue and leave it to calibrate offline.. */
> > +       schedule_delayed_work(&work_data->work,
> > +                             msecs_to_jiffies(SR1P5_SAMPLING_DELAY_MS *
> > +                                              SR1P5_STABLE_SAMPLES));
> > +
> > +       return 0;
> > +}
> > +
> > +/**
> > + * sr_class1p5_disable() - disable for class 1p5
> > + * @voltdm: voltage domain for the sr which needs disabling
> > + * @volt_data: voltagedata to disable
> > + * @is_volt_reset: reset the voltage?
> > + *
> > + * we dont do anything if the class 1p5 is being used. this is because we
> > + * already disable sr at the end of calibration and no h/w loop is actually
> > + * active when this is called.
> > + */
> > +static int sr_class1p5_disable(struct voltagedomain *voltdm,
> > +                              struct omap_volt_data *volt_data,
> > +                              int is_volt_reset)
> > +{
> > +       struct sr_class1p5_work_data *work_data;
> > +
> > +       work_data = get_sr1p5_work(voltdm);
> > +       if (work_data->work_active) {
> > +               /* if volt reset and work is active, we dont allow this */
> > +               if (is_volt_reset)
> > +                       return -EBUSY;
> > +               /* flag work is dead and remove the old work */
> > +               work_data->work_active = false;
> > +               cancel_delayed_work_sync(&work_data->work);
> > +               sr_notifier_control(voltdm, false);
> > +               omap_vp_disable(voltdm);
> > +               sr_disable(voltdm);
> > +       }
> > +
> > +       /* if already calibrated, nothin special to do here.. */
> > +       if (volt_data->volt_calibrated)
> > +               return 0;
> > +
> > +       if (is_volt_reset)
> > +               omap_voltage_reset(voltdm);
> > +       return 0;
> > +}
> > +
> > +/**
> > + * sr_class1p5_configure() - configuration function
> > + * @voldm:     configure for which voltage domain
> > + *
> > + * we dont do much here other than setup some registers for
> > + * the sr module involved.
> > + */
> > +static int sr_class1p5_configure(struct voltagedomain *voltdm)
> > +{
> > +       return sr_configure_errgen(voltdm);
> > +}
> > +
> > +/**
> > + * sr_class1p5_reset_calib() - reset all calibrated voltages
> > + * @srid:      srid to reset the calibration for
> > + * @reset:     reset voltage before we recal?
> > + * @recal:     should I recalibrate my current opp?
> > + *
> > + * if we call this, it means either periodic calibration trigger was
> > + * fired(either from sysfs or other mechanisms) or we have disabled class 1p5,
> > + * meaning we cant trust the calib voltages anymore, it is better to use
> > + * nominal in the system
> > + */
> > +static void sr_class1p5_reset_calib(struct voltagedomain *voltdm, bool reset,
> > +                                   bool recal)
> > +{
> > +       struct sr_class1p5_work_data *work_data;
> > +
> > +       /* I dont need to go further if sr is not present */
> > +       if (!is_sr_enabled(voltdm))
> > +               return;
> > +
> > +       work_data = get_sr1p5_work(voltdm);
> > +
> > +       if (work_data->work_active)
> > +               sr_class1p5_disable(voltdm, work_data->vdata, 0);
> > +
> > +       omap_voltage_calib_reset(voltdm);
> > +
> > +       /*
> > +        * I should now reset the voltages to my nominal to be safe
> > +        */
> > +       if (reset)
> > +               omap_voltage_reset(voltdm);
> > +
> > +       /*
> > +        * I should fire a recalibration for current opp if needed
> > +        * Note: i have just reset my calibrated voltages, and if
> > +        * i call sr_enable equivalent, I will cause a recalibration
> > +        * loop, even though the function is called sr_enable.. we
> > +        * are in class 1.5 ;)
> > +        */
> > +       if (reset && recal)
> > +               sr_class1p5_enable(voltdm, work_data->vdata);
> > +}
> > +
> > +/**
> > + * sr_class1p5_cinit() - class 1p5 init
> > + * @voltdm:            sr voltage domain
> > + * @class_priv_data:   private data for the class
> > + *
> > + * we do class specific initialization like creating sysfs/debugfs entries
> > + * needed, spawning of a kthread if needed etc.
> > + */
> > +static int sr_class1p5_cinit(struct voltagedomain *voltdm,
> > +                            void *class_priv_data)
> > +{
> > +       struct sr_class1p5_work_data *work_data;
> > +       int idx;
> > +
> > +       if (!class_priv_data) {
> > +               pr_err("%s: bad param? no priv data!\n", __func__);
> > +               return -EINVAL;
> > +       }
> > +
> > +       /* setup our work params */
> > +       work_data = get_sr1p5_work(voltdm);
> > +       if (!IS_ERR_OR_NULL(work_data)) {
> > +               pr_err("%s: ooopps.. class already initialized for %s! bug??\n",
> > +                      __func__, voltdm->name);
> > +               return -EINVAL;
> > +       }
> > +       work_data = NULL;
> > +       /* get the next spare work_data */
> > +       for (idx = 0; idx < MAX_VDDS; idx++) {
> > +               if (!class_1p5_data.work_data[idx].voltdm) {
> > +                       work_data = &class_1p5_data.work_data[idx];
> > +                       break;
> > +               }
> > +       }
> > +       if (!work_data) {
> > +               pr_err("%s: no more space for work data for domains!\n",
> > +                       __func__);
> > +               return -ENOMEM;
> > +       }
> > +       work_data->voltdm = voltdm;
> > +       INIT_DELAYED_WORK_DEFERRABLE(&work_data->work, do_calibrate);
> > +       return 0;
> > +}
> > +
> > +/**
> > + * sr_class1p5_cdeinit() - class 1p5 deinitialization
> > + * @voltdm:    voltage domain for which to do this.
> > + * @class_priv_data: class private data for deinitialiation
> > + *
> > + * currently only resets the calibrated voltage forcing dvfs voltages
> > + * to be used in the system
> > + */
> > +static int sr_class1p5_cdeinit(struct voltagedomain *voltdm,
> > +                              void *class_priv_data)
> > +{
> > +       struct sr_class1p5_work_data *work_data;
> > +
> > +       /* setup our work params */
> > +       work_data = get_sr1p5_work(voltdm);
> > +       if (IS_ERR_OR_NULL(work_data)) {
> > +               pr_err("%s: ooopps.. class not initialized for %s! bug??\n",
> > +                      __func__, voltdm->name);
> > +               return -EINVAL;
> > +       }
> > +
> > +       /*
> > +        * we dont have SR periodic calib anymore.. so reset calibs
> > +        * we are already protected by sr debugfs lock, so no lock needed
> > +        * here.
> > +        */
> > +       sr_class1p5_reset_calib(voltdm, true, false);
> > +
> > +       /* reset all data for this work data */
> > +       memset(work_data, 0, sizeof(*work_data));
> > +
> > +       return 0;
> > +}
> > +
> > +/* SR class1p5 structure */
> > +static struct omap_sr_class_data class1p5_data = {
> > +       .enable = sr_class1p5_enable,
> > +       .disable = sr_class1p5_disable,
> > +       .configure = sr_class1p5_configure,
> > +       .class_type = SR_CLASS1P5,
> > +       .class_init = sr_class1p5_cinit,
> > +       .class_deinit = sr_class1p5_cdeinit,
> > +       .notify = sr_class1p5_notify,
> > +       /*
> > +        * trigger for bound - this tells VP that SR has a voltage
> > +        * change. we should ensure transdone is set before reading
> > +        * vp voltage.
> > +        */
> > +       .notify_flags = SR_NOTIFY_MCUBOUND,
> > +       .class_priv_data = (void *)&class_1p5_data,
> > +};
> > +
> > +/**
> > + * sr_class1p5_init() - register class 1p5 as default
> > + *
> > + * board files call this function to use class 1p5, we register with the
> > + * smartreflex subsystem
> > + */
> > +static int __init sr_class1p5_init(void)
> > +{
> > +       int r;
> > +
> > +       /* Enable this class only for OMAP3630 and OMAP4 */
> > +       if (!(cpu_is_omap3630() || cpu_is_omap44xx()))
> > +               return -EINVAL;
> > +
> > +       r = sr_register_class(&class1p5_data);
> > +       if (r) {
> > +               pr_err("SmartReflex class 1.5 driver: "
> > +                      "failed to register with %d\n", r);
> > +       } else {
> > +#if CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY
> > +               INIT_DELAYED_WORK_DEFERRABLE(&recal_work, do_recalibrate);
> > +               schedule_delayed_work(&recal_work, msecs_to_jiffies(
> > +                               CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY));
> > +#endif
> > +               pr_info("SmartReflex class 1.5 driver: initialized (%dms)\n",
> > +                       CONFIG_OMAP_SR_CLASS1P5_RECALIBRATION_DELAY);
> > +       }
> > +       return r;
> > +}
> > +late_initcall(sr_class1p5_init);
> > diff --git a/arch/arm/mach-omap2/smartreflex-class3.c b/arch/arm/mach-omap2/smartreflex-class3.c
> > index 7ac88da..5f7a33e 100644
> > --- a/arch/arm/mach-omap2/smartreflex-class3.c
> > +++ b/arch/arm/mach-omap2/smartreflex-class3.c
> > @@ -21,7 +21,9 @@ static int sr_class3_enable(struct voltagedomain *voltdm,
> >        return sr_enable(voltdm, volt_data);
> >  }
> >
> > -static int sr_class3_disable(struct voltagedomain *voltdm, int is_volt_reset)
> > +static int sr_class3_disable(struct voltagedomain *voltdm,
> > +                               struct omap_volt_data *vdata,
> > +                               int is_volt_reset)
> >  {
> >        omap_vp_disable(voltdm);
> >        sr_disable(voltdm);
> > diff --git a/arch/arm/mach-omap2/smartreflex.c b/arch/arm/mach-omap2/smartreflex.c
> > index 3a5f2f6..bb55b65 100644
> > --- a/arch/arm/mach-omap2/smartreflex.c
> > +++ b/arch/arm/mach-omap2/smartreflex.c
> > @@ -317,7 +317,9 @@ static void sr_stop_vddautocomp(struct omap_sr *sr)
> >        }
> >
> >        if (sr->autocomp_active) {
> > -               sr_class->disable(sr->voltdm, 1);
> > +               sr_class->disable(sr->voltdm,
> > +                               omap_voltage_get_nom_volt(sr->voltdm),
> > +                               1);
> >                if (sr_class->class_deinit &&
> >                    sr_class->class_deinit(sr->voltdm,
> >                            sr_class->class_priv_data)) {
> > @@ -471,6 +473,28 @@ static u32 sr_retrieve_nvalue(struct omap_sr *sr, u32 efuse_offs)
> >  /* Public Functions */
> >
> >  /**
> > + * is_sr_enabled() - is Smart reflex enabled for this domain?
> > + * @voltdm: voltage domain to check
> > + *
> > + * Returns 0 if SR is enabled for this domain, else returns err
> > + */
> > +bool is_sr_enabled(struct voltagedomain *voltdm)
> > +{
> > +       struct omap_sr *sr;
> > +       if (IS_ERR_OR_NULL(voltdm)) {
> > +               pr_warning("%s: invalid param voltdm\n", __func__);
> > +               return false;
> > +       }
> > +       sr = _sr_lookup(voltdm);
> > +       if (IS_ERR(sr)) {
> > +               pr_warning("%s: omap_sr struct for sr_%s not found\n",
> > +                       __func__, voltdm->name);
> > +               return false;
> > +       }
> > +       return sr->autocomp_active;
> > +}
> > +
> > +/**
> >  * sr_configure_errgen() - Configures the smrtreflex to perform AVS using the
> >  *                      error generator module.
> >  * @voltdm:    VDD pointer to which the SR module to be configured belongs to.
> > @@ -839,6 +863,7 @@ void omap_sr_enable(struct voltagedomain *voltdm,
> >  * omap_sr_disable() - API to disable SR without resetting the voltage
> >  *                     processor voltage
> >  * @voltdm:    VDD pointer to which the SR module to be configured belongs to.
> > + * @volt_data: Voltage data to go to
> >  *
> >  * This API is to be called from the kernel in order to disable
> >  * a particular smartreflex module. This API will in turn call
> > @@ -846,7 +871,8 @@ void omap_sr_enable(struct voltagedomain *voltdm,
> >  * the smartreflex class disable not to reset the VP voltage after
> >  * disabling smartreflex.
> >  */
> > -void omap_sr_disable(struct voltagedomain *voltdm)
> > +void omap_sr_disable(struct voltagedomain *voltdm,
> > +               struct omap_volt_data *vdata)
> >  {
> >        struct omap_sr *sr = _sr_lookup(voltdm);
> >
> > @@ -865,7 +891,7 @@ void omap_sr_disable(struct voltagedomain *voltdm)
> >                return;
> >        }
> >
> > -       sr_class->disable(voltdm, 0);
> > +       sr_class->disable(voltdm, vdata, 0);
> >  }
> >
> >  /**
> > @@ -898,7 +924,7 @@ void omap_sr_disable_reset_volt(struct voltagedomain *voltdm)
> >                return;
> >        }
> >
> > -       sr_class->disable(voltdm, 1);
> > +       sr_class->disable(voltdm, omap_voltage_get_nom_volt(voltdm), 1);
> >  }
> >
> >  /**
> > diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c
> > index 77cb0cd..c451835 100644
> > --- a/arch/arm/mach-omap2/voltage.c
> > +++ b/arch/arm/mach-omap2/voltage.c
> > @@ -374,9 +374,45 @@ static int nom_volt_debug_get(void *data, u64 *val)
> >        return 0;
> >  }
> >
> > +static int dyn_volt_debug_get(void *data, u64 *val)
> > +{
> > +       struct omap_vdd_info *vdd = (struct omap_vdd_info *) data;
> > +       struct omap_volt_data *volt_data;
> > +
> > +       if (!vdd) {
> > +               pr_warning("Wrong paramater passed\n");
> > +               return -EINVAL;
> > +       }
> > +       volt_data = omap_voltage_get_nom_volt(&vdd->voltdm);
> > +
> > +       *val = volt_data->volt_dynamic_nominal;
> > +
> > +       return 0;
> > +}
> > +
> > +static int calib_volt_debug_get(void *data, u64 *val)
> > +{
> > +       struct omap_vdd_info *vdd = (struct omap_vdd_info *) data;
> > +       struct omap_volt_data *volt_data;
> > +
> > +       if (!vdd) {
> > +               pr_warning("Wrong paramater passed\n");
> > +               return -EINVAL;
> > +       }
> > +       volt_data = omap_voltage_get_nom_volt(&vdd->voltdm);
> > +
> > +       *val = volt_data->volt_calibrated;
> > +
> > +       return 0;
> > +}
> > +
> >  DEFINE_SIMPLE_ATTRIBUTE(vp_volt_debug_fops, vp_volt_debug_get, NULL, "%llu\n");
> >  DEFINE_SIMPLE_ATTRIBUTE(nom_volt_debug_fops, nom_volt_debug_get, NULL,
> >                                                                "%llu\n");
> > +DEFINE_SIMPLE_ATTRIBUTE(dyn_volt_debug_fops, dyn_volt_debug_get, NULL,
> > +                                                               "%llu\n");
> > +DEFINE_SIMPLE_ATTRIBUTE(calib_volt_debug_fops, calib_volt_debug_get, NULL,
> > +                                                               "%llu\n");
> >  static void vp_latch_vsel(struct omap_vdd_info *vdd)
> >  {
> >        u32 vpconfig;
> > @@ -504,6 +540,12 @@ static void __init vdd_debugfs_init(struct omap_vdd_info *vdd)
> >        (void) debugfs_create_file("curr_nominal_volt", S_IRUGO,
> >                                vdd->debug_dir, (void *) vdd,
> >                                &nom_volt_debug_fops);
> > +       (void) debugfs_create_file("curr_dyn_nominal_volt", S_IRUGO,
> > +                               vdd->debug_dir, (void *) vdd,
> > +                               &dyn_volt_debug_fops);
> > +       (void) debugfs_create_file("curr_calibrated_volt", S_IRUGO,
> > +                               vdd->debug_dir, (void *) vdd,
> > +                               &calib_volt_debug_fops);
> >  }
> >
> >  /* Voltage scale and accessory APIs */
> > @@ -1132,6 +1174,33 @@ struct omap_volt_data *omap_voltage_get_nom_volt(struct voltagedomain *voltdm)
> >  }
> >
> >  /**
> > + * omap_voltage_calib_reset() - reset the calibrated voltage entries
> > + * @voltdm: voltage domain to reset the entries for
> > + *
> > + * when the calibrated entries are no longer valid, this api allows
> > + * the calibrated voltages to be reset.
> > + */
> > +int omap_voltage_calib_reset(struct voltagedomain *voltdm)
> > +{
> > +       struct omap_vdd_info *vdd;
> > +       struct omap_volt_data *volt_data;
> > +
> > +       if (IS_ERR_OR_NULL(voltdm)) {
> > +               pr_warning("%s: VDD specified does not exist!\n", __func__);
> > +               return -EINVAL;
> > +       }
> > +
> > +       vdd = container_of(voltdm, struct omap_vdd_info, voltdm);
> > +       volt_data = vdd->volt_data;
> > +       /* reset the calibrated voltages as 0 */
> > +       while (volt_data->volt_nominal) {
> > +               volt_data->volt_calibrated = 0;
> > +               volt_data++;
> > +       }
> > +       return 0;
> > +}
> > +
> > +/**
> >  * omap_vp_get_curr_volt() - API to get the current vp voltage.
> >  * @voltdm:    pointer to the VDD.
> >  *
> > diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
> > index b6333ae..dba7939 100644
> > --- a/arch/arm/plat-omap/Kconfig
> > +++ b/arch/arm/plat-omap/Kconfig
> > @@ -67,6 +67,23 @@ config OMAP_SMARTREFLEX_CLASS3
> >          Class 3 implementation of Smartreflex employs continuous hardware
> >          voltage calibration.
> >
> > +config OMAP_SMARTREFLEX_CLASS1P5
> > +       bool "Class 1.5 mode of Smartreflex Implementation"
> > +       depends on OMAP_SMARTREFLEX && TWL4030_CORE
> > +       help
> > +         Say Y to enable Class 1.5 implementation of Smartreflex
> > +         Class 1.5 implementation of Smartreflex employs software controlled
> > +         hardware voltage calibration.
> > +
> > +config OMAP_SR_CLASS1P5_RECALIBRATION_DELAY
> > +       int "Class 1.5 mode recalibration recalibration delay(ms)"
> > +       depends on OMAP_SMARTREFLEX_CLASS1P5
> > +       default 86400000
> > +       help
> > +         Setup the recalibration delay in milliseconds. Use 0 for never doing
> > +         a recalibration. Defaults to recommended recalibration every 24hrs.
> > +         If you do not understand this, use the default.
> > +
> >  config OMAP_RESET_CLOCKS
> >        bool "Reset unused clocks during boot"
> >        depends on ARCH_OMAP
> > diff --git a/arch/arm/plat-omap/include/plat/smartreflex.h b/arch/arm/plat-omap/include/plat/smartreflex.h
> > index 07f35b2..ee5c58f 100644
> > --- a/arch/arm/plat-omap/include/plat/smartreflex.h
> > +++ b/arch/arm/plat-omap/include/plat/smartreflex.h
> > @@ -167,6 +167,7 @@ struct omap_sr_pmic_data {
> >  #define SR_CLASS1      0x1
> >  #define SR_CLASS2      0x2
> >  #define SR_CLASS3      0x3
> > +#define SR_CLASS1P5    0x4
> >
> >  /**
> >  * struct omap_sr_class_data - Smartreflex class driver info
> > @@ -187,7 +188,9 @@ struct omap_sr_pmic_data {
> >  struct omap_sr_class_data {
> >        int (*enable)(struct voltagedomain *voltdm,
> >                        struct omap_volt_data *volt_data);
> > -       int (*disable)(struct voltagedomain *voltdm, int is_volt_reset);
> > +       int (*disable)(struct voltagedomain *voltdm,
> > +                       struct omap_volt_data *volt_data,
> > +                       int is_volt_reset);
> >        int (*class_init)(struct voltagedomain *voltdm, void *class_priv_data);
> >        int (*class_deinit)(struct voltagedomain *voltdm,
> >                        void *class_priv_data);
> > @@ -235,7 +238,8 @@ struct omap_sr_data {
> >  /* Smartreflex module enable/disable interface */
> >  void omap_sr_enable(struct voltagedomain *voltdm,
> >                        struct omap_volt_data *volt_data);
> > -void omap_sr_disable(struct voltagedomain *voltdm);
> > +void omap_sr_disable(struct voltagedomain *voltdm,
> > +                       struct omap_volt_data *volt_data);
> >  void omap_sr_disable_reset_volt(struct voltagedomain *voltdm);
> >
> >  /* API to register the pmic specific data with the smartreflex driver. */
> > @@ -250,6 +254,7 @@ int sr_configure_minmax(struct voltagedomain *voltdm);
> >
> >  /* API to register the smartreflex class driver with the smartreflex driver */
> >  int sr_register_class(struct omap_sr_class_data *class_data);
> > +bool is_sr_enabled(struct voltagedomain *voltdm);
> >  #else
> >  static inline void omap_sr_enable(struct voltagedomain *voltdm) {}
> >  static inline void omap_sr_disable(struct voltagedomain *voltdm) {}
> > @@ -264,5 +269,9 @@ static inline void omap_sr_disable_reset_volt(
> >                struct voltagedomain *voltdm) {}
> >  static inline void omap_sr_register_pmic(
> >                struct omap_sr_pmic_data *pmic_data) {}
> > +static inline bool is_sr_enabled(struct voltagedomain *voltdm)
> > +{
> > +       return false;
> > +}
> >  #endif
> >  #endif
> > diff --git a/arch/arm/plat-omap/include/plat/voltage.h b/arch/arm/plat-omap/include/plat/voltage.h
> > index 332c581..54445f0 100644
> > --- a/arch/arm/plat-omap/include/plat/voltage.h
> > +++ b/arch/arm/plat-omap/include/plat/voltage.h
> > @@ -58,6 +58,8 @@
> >  #define OMAP4430_VDD_CORE_OPP50_UV             930000
> >  #define OMAP4430_VDD_CORE_OPP100_UV            1100000
> >
> > +#define OMAP3PLUS_DYNAMIC_NOMINAL_MARGIN_UV    50000
> > +
> >  /**
> >  * struct voltagedomain - omap voltage domain global structure.
> >  * @name:      Name of the voltage domain which can be used as a unique
> > @@ -81,6 +83,8 @@ struct voltagedomain {
> >  */
> >  struct omap_volt_data {
> >        u32     volt_nominal;
> > +       u32     volt_calibrated;
> > +       u32     volt_dynamic_nominal;
> >        u32     sr_efuse_offs;
> >        u8      sr_errminlimit;
> >        u8      vp_errgain;
> > @@ -127,6 +131,7 @@ struct omap_volt_data *omap_voltage_get_nom_volt(struct voltagedomain *voltdm);
> >  bool omap_vp_is_transdone(struct voltagedomain *voltdm);
> >  bool omap_vp_clear_transdone(struct voltagedomain *voltdm);
> >  struct dentry *omap_voltage_get_dbgdir(struct voltagedomain *voltdm);
> > +int omap_voltage_calib_reset(struct voltagedomain *voltdm);
> >  #ifdef CONFIG_PM
> >  int omap_voltage_register_pmic(struct voltagedomain *voltdm,
> >                struct omap_volt_pmic_info *pmic_info);
> > @@ -160,7 +165,23 @@ static inline unsigned long omap_get_operation_voltage(
> >  {
> >        if (IS_ERR_OR_NULL(vdata))
> >                return 0;
> > -       return vdata->volt_nominal;
> > +       return (vdata->volt_calibrated) ? vdata->volt_calibrated :
> > +               (vdata->volt_dynamic_nominal) ? vdata->volt_dynamic_nominal :
> > +                       vdata->volt_nominal;
> >  }
> >
> > +/* what is my dynamic nominal? */
> > +static inline unsigned long omap_get_dyn_nominal(struct omap_volt_data *vdata)
> > +{
> > +       if (IS_ERR_OR_NULL(vdata))
> > +               return 0;
> > +       if (vdata->volt_calibrated) {
> > +               unsigned long v = vdata->volt_calibrated +
> > +                       OMAP3PLUS_DYNAMIC_NOMINAL_MARGIN_UV;
> > +               if (v > vdata->volt_nominal)
> > +                       return vdata->volt_nominal;
> > +               return v;
> > +       }
> > +       return vdata->volt_nominal;
> > +}
> >  #endif
> > --
> > 1.7.1
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-omap" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> I have tested this Patch Series on OMAP 3630 SDP,  for MPU and IVA Powerdomains
Could you clarify on null pointer issue: on SDP3630? or OMAP4SDP? I
see there is a risk with OMAP4 where there is a bug in the following
scenario:
bootloader setups the OPP frequency for an OPP(e.g. 1GHz) which is
disabled by default on OPP table in kernel. this needs to be cleanly
fixed in pm.c, at the same time, the exposed functions in class1p5
needs parameter validation as well.

> it throws error log "Unable to refer to NULL pointer" if
> curr_nominal_volt, curr_calibrated_volt
> or curr_dynamical_volt is accessed through debugfs.
> Could you please provide fix for this.

Regards,
Nishanth Menon
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