Re: [PATCH v3 5/6] coresight: etm4x: save/restore state across CPU low power states

[Andrew Murray <andrew.murray@arm.com>]

On Mon, Jul 15, 2019 at 03:22:47PM +0100, Mike Leach wrote:
> HI Andrew,
> 
> On Thu, 11 Jul 2019 at 17:01, Andrew Murray <andrew.murray@arm.com> wrote:
> >
> > Some hardware will ignore bit TRCPDCR.PU which is used to signal
> > to hardware that power should not be removed from the trace unit.
> > Let's mitigate against this by conditionally saving and restoring
> > the trace unit state when the CPU enters low power states.
> >
> > This patchset introduces a firmware property named
> > 'arm,coresight-needs-save-restore' - when this is present the
> > hardware state will be conditionally saved and restored.
> >
> > A module parameter 'pm_save_enable' is also introduced which can
> > be configured to override the firmware property. This can be set
> > to never allow save/restore, to conditionally allow it, or to
> > do as the firmware indicates (default).
> >
> > The hardware state is only ever saved and restored when the claim
> > tags indicate that coresight is in use.
> >
> > Signed-off-by: Andrew Murray <andrew.murray@arm.com>
> > ---
> >  drivers/hwtracing/coresight/coresight-etm4x.c | 324 ++++++++++++++++++
> >  drivers/hwtracing/coresight/coresight-etm4x.h |  62 ++++
> >  drivers/hwtracing/coresight/coresight.c       |   2 +-
> >  include/linux/coresight.h                     |   8 +
> >  4 files changed, 395 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> > index d993359e2117..b0bd8158bf13 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> > @@ -18,6 +18,7 @@
> >  #include <linux/stat.h>
> >  #include <linux/clk.h>
> >  #include <linux/cpu.h>
> > +#include <linux/cpu_pm.h>
> >  #include <linux/coresight.h>
> >  #include <linux/coresight-pmu.h>
> >  #include <linux/pm_wakeup.h>
> > @@ -26,6 +27,7 @@
> >  #include <linux/uaccess.h>
> >  #include <linux/perf_event.h>
> >  #include <linux/pm_runtime.h>
> > +#include <linux/property.h>
> >  #include <asm/sections.h>
> >  #include <asm/local.h>
> >  #include <asm/virt.h>
> > @@ -37,6 +39,15 @@ static int boot_enable;
> >  module_param(boot_enable, int, 0444);
> >  MODULE_PARM_DESC(boot_enable, "Enable tracing on boot");
> >
> > +#define PARAM_PM_SAVE_NEVER    0 /* never save/restore state */
> > +#define PARAM_PM_SAVE_ALWAYS   1 /* always save/restore state */
> > +#define PARAM_PM_SAVE_FIRMWARE 2 /* only save/restore if firmware flag set */
> > +
> > +static int pm_save_enable = PARAM_PM_SAVE_FIRMWARE;
> > +module_param(pm_save_enable, int, 0644);
> > +MODULE_PARM_DESC(pm_save_enable,
> > +       "Save/restore state on power down: 0 = never, 1 = always, 2 = firmware");
> > +
> >  /* The number of ETMv4 currently registered */
> >  static int etm4_count;
> >  static struct etmv4_drvdata *etmdrvdata[NR_CPUS];
> > @@ -54,6 +65,14 @@ static void etm4_os_unlock(struct etmv4_drvdata *drvdata)
> >         isb();
> >  }
> >
> > +static void etm4_os_lock(struct etmv4_drvdata *drvdata)
> > +{
> > +       /* Writing 0x1 to TRCOSLAR locks the trace registers */
> > +       writel_relaxed(0x1, drvdata->base + TRCOSLAR);
> > +       drvdata->os_unlock = false;
> > +       isb();
> > +}
> > +
> >  static bool etm4_arch_supported(u8 arch)
> >  {
> >         /* Mask out the minor version number */
> > @@ -1085,6 +1104,303 @@ static void etm4_init_trace_id(struct etmv4_drvdata *drvdata)
> >         drvdata->trcid = coresight_get_trace_id(drvdata->cpu);
> >  }
> >
> > +#ifdef CONFIG_CPU_PM
> > +static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
> > +{
> > +       int i, ret = 0;
> > +       u32 control;
> > +       struct etmv4_save_state *state;
> > +       struct device *etm_dev = &drvdata->csdev->dev;
> > +
> > +       /*
> > +        * As recommended by 3.4.1 ("The procedure when powering down the PE")
> > +        * of ARM IHI 0064D
> > +        */
> > +       dsb(sy);
> > +       isb();
> > +
> > +       CS_UNLOCK(drvdata->base);
> > +
> > +       /* Lock the OS lock to disable trace and external debugger access */
> > +       etm4_os_lock(drvdata);
> > +
> > +       /* wait for TRCSTATR.PMSTABLE to go up */
> > +       if (coresight_timeout(drvdata->base, TRCSTATR,
> > +                                       TRCSTATR_PMSTABLE_BIT, 1)) {
> > +               dev_err(etm_dev,
> > +                       "timeout while waiting for PM Stable Status\n");
> > +               etm4_os_unlock(drvdata);
> > +               ret = -EBUSY;
> > +               goto out;
> > +       }
> > +
> > +       state = &drvdata->save_state;
> > +
> > +       state->trcprgctlr = readl(drvdata->base + TRCPRGCTLR);
> > +       state->trcprocselr = readl(drvdata->base + TRCPROCSELR);
> > +       state->trcconfigr = readl(drvdata->base + TRCCONFIGR);
> > +       state->trcauxctlr = readl(drvdata->base + TRCAUXCTLR);
> > +       state->trceventctl0r = readl(drvdata->base + TRCEVENTCTL0R);
> > +       state->trceventctl1r = readl(drvdata->base + TRCEVENTCTL1R);
> > +       state->trcstallctlr = readl(drvdata->base + TRCSTALLCTLR);
> > +       state->trctsctlr = readl(drvdata->base + TRCTSCTLR);
> > +       state->trcsyncpr = readl(drvdata->base + TRCSYNCPR);
> > +       state->trcccctlr = readl(drvdata->base + TRCCCCTLR);
> > +       state->trcbbctlr = readl(drvdata->base + TRCBBCTLR);
> > +       state->trctraceidr = readl(drvdata->base + TRCTRACEIDR);
> > +       state->trcqctlr = readl(drvdata->base + TRCQCTLR);
> > +
> > +       state->trcvictlr = readl(drvdata->base + TRCVICTLR);
> > +       state->trcviiectlr = readl(drvdata->base + TRCVIIECTLR);
> > +       state->trcvissctlr = readl(drvdata->base + TRCVISSCTLR);
> > +       state->trcvipcssctlr = readl(drvdata->base + TRCVIPCSSCTLR);
> > +       state->trcvdctlr = readl(drvdata->base + TRCVDCTLR);
> > +       state->trcvdsacctlr = readl(drvdata->base + TRCVDSACCTLR);
> > +       state->trcvdarcctlr = readl(drvdata->base + TRCVDARCCTLR);
> > +
> > +       for (i = 0; i < drvdata->nrseqstate; i++)
> > +               state->trcseqevr[i] = readl(drvdata->base + TRCSEQEVRn(i));
> > +
> > +       state->trcseqrstevr = readl(drvdata->base + TRCSEQRSTEVR);
> > +       state->trcseqstr = readl(drvdata->base + TRCSEQSTR);
> > +       state->trcextinselr = readl(drvdata->base + TRCEXTINSELR);
> > +
> > +       for (i = 0; i < drvdata->nr_cntr; i++) {
> > +               state->trccntrldvr[i] = readl(drvdata->base + TRCCNTRLDVRn(i));
> > +               state->trccntctlr[i] = readl(drvdata->base + TRCCNTCTLRn(i));
> > +               state->trccntvr[i] = readl(drvdata->base + TRCCNTVRn(i));
> > +       }
> > +
> > +       for (i = 0; i < drvdata->nr_resource * 2; i++)
> > +               state->trcrsctlr[i] = readl(drvdata->base + TRCRSCTLRn(i));
> > +
> > +       for (i = 0; i < drvdata->nr_ss_cmp; i++) {
> > +               state->trcssccr[i] = readl(drvdata->base + TRCSSCCRn(i));
> > +               state->trcsscsr[i] = readl(drvdata->base + TRCSSCSRn(i));
> > +               state->trcsspcicr[i] = readl(drvdata->base + TRCSSPCICRn(i));
> > +       }
> > +
> > +       for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
> > +               state->trcacvr[i] = readl(drvdata->base + TRCACVRn(i));
> > +               state->trcacatr[i] = readl(drvdata->base + TRCACATRn(i));
> > +       }
> > +
> > +       /*
> > +        * Data trace stream is architecturally prohibited for A profile cores
> > +        * so we don't save (or later restore) trcdvcvr and trcdvcmr - As per
> > +        * section 1.3.4 ("Possible functional configurations of an ETMv4 trace
> > +        * unit") of ARM IHI 0064D.
> > +        */
> > +
> > +       for (i = 0; i < drvdata->numcidc; i++)
> > +               state->trccidcvr[i] = readl(drvdata->base + TRCCIDCVRn(i));
> > +
> > +       for (i = 0; i < drvdata->numvmidc; i++)
> > +               state->trcvmidcvr[i] = readl(drvdata->base + TRCVMIDCVRn(i));
> > +
> > +       state->trccidcctlr0 = readl(drvdata->base + TRCCIDCCTLR0);
> > +       state->trccidcctlr1 = readl(drvdata->base + TRCCIDCCTLR1);
> > +
> > +       state->trcvmidcctlr0 = readl(drvdata->base + TRCVMIDCCTLR0);
> > +       state->trcvmidcctlr0 = readl(drvdata->base + TRCVMIDCCTLR1);
> > +
> > +       state->trcclaimset = readl(drvdata->base + TRCCLAIMCLR);
> > +
> > +       /* wait for TRCSTATR.IDLE to go up */
> > +       if (coresight_timeout(drvdata->base, TRCSTATR, TRCSTATR_IDLE_BIT, 1)) {
> > +               dev_err(etm_dev,
> > +                       "timeout while waiting for Idle Trace Status\n");
> > +               etm4_os_unlock(drvdata);
> > +               ret = -EBUSY;
> > +               goto out;
> > +       }
> > +
> > +       drvdata->state_needs_restore = true;
> > +
> > +       /*
> > +        * Power can be removed from the trace unit now. We do this to
> > +        * potentially save power on systems that respect the TRCPDCR_PU
> > +        * despite requesting software to save/restore state.
> > +        */
> > +       control = readl_relaxed(drvdata->base + TRCPDCR);
> > +       control &= ~TRCPDCR_PU;
> > +       writel_relaxed(control, drvdata->base + TRCPDCR);
> > +
> 
> Removing the power is fine, except you are not remembering the state
> for restore later.
> 
> > +out:
> > +       CS_LOCK(drvdata->base);
> > +       return ret;
> > +}
> > +
> > +static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
> > +{
> > +       int i;
> > +       struct etmv4_save_state *state;
> > +
> > +       state = &drvdata->save_state;
> > +
> > +       CS_UNLOCK(drvdata->base);
> > +
> > +       writel_relaxed(state->trcclaimset, drvdata->base + TRCCLAIMSET);
> > +
> > +       writel_relaxed(state->trcprgctlr, drvdata->base + TRCPRGCTLR);
> > +       writel_relaxed(state->trcprocselr, drvdata->base + TRCPROCSELR);
> > +       writel_relaxed(state->trcconfigr, drvdata->base + TRCCONFIGR);
> > +       writel_relaxed(state->trcauxctlr, drvdata->base + TRCAUXCTLR);
> > +       writel_relaxed(state->trceventctl0r, drvdata->base + TRCEVENTCTL0R);
> > +       writel_relaxed(state->trceventctl1r, drvdata->base + TRCEVENTCTL1R);
> > +       writel_relaxed(state->trcstallctlr, drvdata->base + TRCSTALLCTLR);
> > +       writel_relaxed(state->trctsctlr, drvdata->base + TRCTSCTLR);
> > +       writel_relaxed(state->trcsyncpr, drvdata->base + TRCSYNCPR);
> > +       writel_relaxed(state->trcccctlr, drvdata->base + TRCCCCTLR);
> > +       writel_relaxed(state->trcbbctlr, drvdata->base + TRCBBCTLR);
> > +       writel_relaxed(state->trctraceidr, drvdata->base + TRCTRACEIDR);
> > +       writel_relaxed(state->trcqctlr, drvdata->base + TRCQCTLR);
> > +
> > +       writel_relaxed(state->trcvictlr, drvdata->base + TRCVICTLR);
> > +       writel_relaxed(state->trcviiectlr, drvdata->base + TRCVIIECTLR);
> > +       writel_relaxed(state->trcvissctlr, drvdata->base + TRCVISSCTLR);
> > +       writel_relaxed(state->trcvipcssctlr, drvdata->base + TRCVIPCSSCTLR);
> > +       writel_relaxed(state->trcvdctlr, drvdata->base + TRCVDCTLR);
> > +       writel_relaxed(state->trcvdsacctlr, drvdata->base + TRCVDSACCTLR);
> > +       writel_relaxed(state->trcvdarcctlr, drvdata->base + TRCVDARCCTLR);
> > +
> > +       for (i = 0; i < drvdata->nrseqstate; i++)
> > +               writel_relaxed(state->trcseqevr[i],
> > +                                       drvdata->base + TRCSEQEVRn(i));
> > +
> > +       writel_relaxed(state->trcseqrstevr, drvdata->base + TRCSEQRSTEVR);
> > +       writel_relaxed(state->trcseqstr, drvdata->base + TRCSEQSTR);
> > +       writel_relaxed(state->trcextinselr, drvdata->base + TRCEXTINSELR);
> > +
> > +       for (i = 0; i < drvdata->nr_cntr; i++) {
> > +               writel_relaxed(state->trccntrldvr[i],
> > +                                       drvdata->base + TRCCNTRLDVRn(i));
> > +               writel_relaxed(state->trccntctlr[i],
> > +                                       drvdata->base + TRCCNTCTLRn(i));
> > +               writel_relaxed(state->trccntvr[i],
> > +                                       drvdata->base + TRCCNTVRn(i));
> > +       }
> > +
> > +       for (i = 0; i < drvdata->nr_resource * 2; i++)
> > +               writel_relaxed(state->trcrsctlr[i],
> > +                                       drvdata->base + TRCRSCTLRn(i));
> > +
> > +       for (i = 0; i < drvdata->nr_ss_cmp; i++) {
> > +               writel_relaxed(state->trcssccr[i],
> > +                                       drvdata->base + TRCSSCCRn(i));
> > +               writel_relaxed(state->trcsscsr[i],
> > +                                       drvdata->base + TRCSSCSRn(i));
> > +               writel_relaxed(state->trcsspcicr[i],
> > +                                       drvdata->base + TRCSSPCICRn(i));
> > +       }
> > +
> > +       for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
> > +               writel_relaxed(state->trcacvr[i],
> > +                                       drvdata->base + TRCACVRn(i));
> > +               writel_relaxed(state->trcacatr[i],
> > +                                       drvdata->base + TRCACATRn(i));
> > +       }
> > +
> > +       for (i = 0; i < drvdata->numcidc; i++)
> > +               writel_relaxed(state->trccidcvr[i],
> > +                                       drvdata->base + TRCCIDCVRn(i));
> > +
> > +       for (i = 0; i < drvdata->numvmidc; i++)
> > +               writel_relaxed(state->trcvmidcvr[i],
> > +                                       drvdata->base + TRCVMIDCVRn(i));
> > +
> > +       writel_relaxed(state->trccidcctlr0, drvdata->base + TRCCIDCCTLR0);
> > +       writel_relaxed(state->trccidcctlr1, drvdata->base + TRCCIDCCTLR1);
> > +
> > +       writel_relaxed(state->trcvmidcctlr0, drvdata->base + TRCVMIDCCTLR0);
> > +       writel_relaxed(state->trcvmidcctlr0, drvdata->base + TRCVMIDCCTLR1);
> > +
> > +       writel_relaxed(state->trcclaimset, drvdata->base + TRCCLAIMSET);
> > +
> > +       drvdata->state_needs_restore = false;
> > +
> > +       /*
> > +        * Request to keep the trace unit powered and also
> > +        * emulation of powerdown
> > +        */
> > +       writel_relaxed(readl_relaxed(drvdata->base + TRCPDCR) | TRCPDCR_PU,
> > +                      drvdata->base + TRCPDCR);
> > +
> 
> This sets the PU bit irrespective of the value on power down. The bit
> should be restored to the state on power down not unconditionally set.

My rationale here was to save/restore only the registers listed in 3.4.1
of the spec (ARM IHI 0064D, "The procedure when powering down the PE") -
though the TRCPDCR isn't listed there.

I originally added the toggle of the PU bit to keep the state inline with
that set by etm4_[enable,disable]_hw. I.e. without save/restore, when
self-hosted these functions will ensure the PU bit is always set anyway.
Thus making the change you suggest has only an impact on externally-hosted
debug when the debugger doesn't set the PU bit.

I'm happy to make this change, however is there any reason why an external
debugger wouldn't set this bit? What harm does it do by always setting it
here?

Thanks,

Andrew Murray

> 
> Regards
> 
> Mike
> 
> 
> > +       /*
> > +        * As recommended by section 4.3.7 ("Synchronization when using the
> > +        * memory-mapped interface") of ARM IHI 0064D
> > +        */
> > +       dsb(sy);
> > +       isb();
> > +
> > +       /* Unlock the OS lock to re-enable trace and external debug access */
> > +       etm4_os_unlock(drvdata);
> > +       CS_LOCK(drvdata->base);
> > +}
> > +
> > +static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
> > +                             void *v)
> > +{
> > +       struct etmv4_drvdata *drvdata;
> > +       unsigned int cpu = smp_processor_id();
> > +
> > +       if (!etmdrvdata[cpu])
> > +               return 0;
> > +
> > +       drvdata = etmdrvdata[cpu];
> > +
> > +       if (pm_save_enable == PARAM_PM_SAVE_NEVER ||
> > +           (pm_save_enable == PARAM_PM_SAVE_FIRMWARE &&
> > +            !drvdata->pm_save_enable))
> > +               return NOTIFY_OK;
> > +
> > +       if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
> > +               return NOTIFY_BAD;
> > +
> > +       switch (cmd) {
> > +       case CPU_PM_ENTER:
> > +               /* save the state if coresight is in use */
> > +               if (coresight_is_claimed_any(drvdata->base))
> > +                       if (etm4_cpu_save(drvdata))
> > +                               return NOTIFY_BAD;
> > +               break;
> > +       case CPU_PM_EXIT:
> > +       case CPU_PM_ENTER_FAILED:
> > +               /* trcclaimset is set when there is state to restore */
> > +               if (drvdata->state_needs_restore)
> > +                       etm4_cpu_restore(drvdata);
> > +               break;
> > +       default:
> > +               return NOTIFY_DONE;
> > +       }
> > +
> > +       return NOTIFY_OK;
> > +}
> > +
> > +static struct notifier_block etm4_cpu_pm_nb = {
> > +       .notifier_call = etm4_cpu_pm_notify,
> > +};
> > +
> > +static int etm4_cpu_pm_register(void)
> > +{
> > +       return cpu_pm_register_notifier(&etm4_cpu_pm_nb);
> > +}
> > +
> > +static void etm4_cpu_pm_unregister(void)
> > +{
> > +       cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
> > +}
> > +#else
> > +static int etm4_cpu_pm_register(void) { return 0; }
> > +static void etm4_cpu_pm_unregister(void) { }
> > +#endif
> > +
> > +static inline bool etm4_needs_save_restore(struct device *dev)
> > +{
> > +       return fwnode_property_present(dev->fwnode,
> > +                                      "arm,coresight-needs-save-restore");
> > +}
> > +
> >  static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> >  {
> >         int ret;
> > @@ -1101,6 +1417,8 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> >
> >         dev_set_drvdata(dev, drvdata);
> >
> > +       drvdata->pm_save_enable = etm4_needs_save_restore(dev);
> > +
> >         /* Validity for the resource is already checked by the AMBA core */
> >         base = devm_ioremap_resource(dev, res);
> >         if (IS_ERR(base))
> > @@ -1132,6 +1450,10 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> >                 if (ret < 0)
> >                         goto err_arch_supported;
> >                 hp_online = ret;
> > +
> > +               ret = etm4_cpu_pm_register();
> > +               if (ret)
> > +                       goto err_arch_supported;
> >         }
> >
> >         cpus_read_unlock();
> > @@ -1182,6 +1504,8 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> >
> >  err_arch_supported:
> >         if (--etm4_count == 0) {
> > +               etm4_cpu_pm_unregister();
> > +
> >                 cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
> >                 if (hp_online)
> >                         cpuhp_remove_state_nocalls(hp_online);
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> > index 4523f10ddd0f..c31634c64f87 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> > @@ -175,6 +175,7 @@
> >                                          ETM_MODE_EXCL_USER)
> >
> >  #define TRCSTATR_IDLE_BIT              0
> > +#define TRCSTATR_PMSTABLE_BIT          1
> >  #define ETM_DEFAULT_ADDR_COMP          0
> >
> >  /* PowerDown Control Register bits */
> > @@ -281,6 +282,63 @@ struct etmv4_config {
> >         u32                             ext_inp;
> >  };
> >
> > +/**
> > + * struct etm4_save_state - state to be preserved when ETM is without power
> > + */
> > +struct etmv4_save_state {
> > +       u32     trcprgctlr;
> > +       u32     trcprocselr;
> > +       u32     trcconfigr;
> > +       u32     trcauxctlr;
> > +       u32     trceventctl0r;
> > +       u32     trceventctl1r;
> > +       u32     trcstallctlr;
> > +       u32     trctsctlr;
> > +       u32     trcsyncpr;
> > +       u32     trcccctlr;
> > +       u32     trcbbctlr;
> > +       u32     trctraceidr;
> > +       u32     trcqctlr;
> > +
> > +       u32     trcvictlr;
> > +       u32     trcviiectlr;
> > +       u32     trcvissctlr;
> > +       u32     trcvipcssctlr;
> > +       u32     trcvdctlr;
> > +       u32     trcvdsacctlr;
> > +       u32     trcvdarcctlr;
> > +
> > +       u32     trcseqevr[ETM_MAX_SEQ_STATES];
> > +       u32     trcseqrstevr;
> > +       u32     trcseqstr;
> > +       u32     trcextinselr;
> > +       u32     trccntrldvr[ETMv4_MAX_CNTR];
> > +       u32     trccntctlr[ETMv4_MAX_CNTR];
> > +       u32     trccntvr[ETMv4_MAX_CNTR];
> > +
> > +       u32     trcrsctlr[ETM_MAX_RES_SEL * 2];
> > +
> > +       u32     trcssccr[ETM_MAX_SS_CMP];
> > +       u32     trcsscsr[ETM_MAX_SS_CMP];
> > +       u32     trcsspcicr[ETM_MAX_SS_CMP];
> > +
> > +       u64     trcacvr[ETM_MAX_SINGLE_ADDR_CMP];
> > +       u64     trcacatr[ETM_MAX_SINGLE_ADDR_CMP];
> > +       u64     trccidcvr[ETMv4_MAX_CTXID_CMP];
> > +       u32     trcvmidcvr[ETM_MAX_VMID_CMP];
> > +       u32     trccidcctlr0;
> > +       u32     trccidcctlr1;
> > +       u32     trcvmidcctlr0;
> > +       u32     trcvmidcctlr1;
> > +
> > +       u32     trcclaimset;
> > +
> > +       u32     cntr_val[ETMv4_MAX_CNTR];
> > +       u32     seq_state;
> > +       u32     vinst_ctrl;
> > +       u32     ss_status[ETM_MAX_SS_CMP];
> > +};
> > +
> >  /**
> >   * struct etm4_drvdata - specifics associated to an ETM component
> >   * @base:       Memory mapped base address for this component.
> > @@ -336,6 +394,7 @@ struct etmv4_config {
> >   * @atbtrig:   If the implementation can support ATB triggers
> >   * @lpoverride:        If the implementation can support low-power state over.
> >   * @config:    structure holding configuration parameters.
> > + * @save_state:        State to be preserved across power loss
> >   */
> >  struct etmv4_drvdata {
> >         void __iomem                    *base;
> > @@ -367,6 +426,7 @@ struct etmv4_drvdata {
> >         u8                              q_support;
> >         bool                            sticky_enable;
> >         bool                            boot_enable;
> > +       bool                            pm_save_enable;
> >         bool                            os_unlock;
> >         bool                            instrp0;
> >         bool                            trcbb;
> > @@ -381,6 +441,8 @@ struct etmv4_drvdata {
> >         bool                            atbtrig;
> >         bool                            lpoverride;
> >         struct etmv4_config             config;
> > +       struct etmv4_save_state         save_state;
> > +       bool                            state_needs_restore;
> >  };
> >
> >  /* Address comparator access types */
> > diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
> > index 86d1fc2c1bd4..aba71a5a025f 100644
> > --- a/drivers/hwtracing/coresight/coresight.c
> > +++ b/drivers/hwtracing/coresight/coresight.c
> > @@ -140,7 +140,7 @@ static inline bool coresight_is_claimed_self_hosted(void __iomem *base)
> >         return coresight_read_claim_tags(base) == CORESIGHT_CLAIM_SELF_HOSTED;
> >  }
> >
> > -static inline bool coresight_is_claimed_any(void __iomem *base)
> > +bool coresight_is_claimed_any(void __iomem *base)
> >  {
> >         return coresight_read_claim_tags(base) != 0;
> >  }
> > diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> > index a2b68823717b..c3a875dffe65 100644
> > --- a/include/linux/coresight.h
> > +++ b/include/linux/coresight.h
> > @@ -285,6 +285,9 @@ extern void coresight_disclaim_device(void __iomem *base);
> >  extern void coresight_disclaim_device_unlocked(void __iomem *base);
> >  extern char *coresight_alloc_device_name(struct coresight_dev_list *devs,
> >                                          struct device *dev);
> > +
> > +extern bool coresight_is_claimed_any(void __iomem *base);
> > +
> >  #else
> >  static inline struct coresight_device *
> >  coresight_register(struct coresight_desc *desc) { return NULL; }
> > @@ -307,6 +310,11 @@ static inline int coresight_claim_device(void __iomem *base)
> >  static inline void coresight_disclaim_device(void __iomem *base) {}
> >  static inline void coresight_disclaim_device_unlocked(void __iomem *base) {}
> >
> > +static inline bool coresight_is_claimed_any(void __iomem *base)
> > +{
> > +       return false;
> > +}
> > +
> >  #endif
> >
> >  extern int coresight_get_cpu(struct device *dev);
> > --
> > 2.21.0
> >
> 
> 
> -- 
> Mike Leach
> Principal Engineer, ARM Ltd.
> Manchester Design Centre. UK

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