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

Gulati, Shweta
2011-03-01T09:54:04Z

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
>
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>
I have tested this Patch Series on OMAP 3630 SDP, for MPU and IVA Powerdomains
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.

--
Thanks,
Regards,
Shweta
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