Re: [PATCH v4 5/6] coresight: etm4x: save/restore state across CPU low power states

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

On Wed, Jul 31, 2019 at 09:16:08AM +0100, Mike Leach wrote:
> Hi,
> 
> Since the decision has apparently been made to ignore the needs of external debug agents, then the "state" struct & variable used in this and the previously mentioned issues around allocating it are un-necessary complication. Simply use the existing config in the driver that contains all of the values that you need - and save on additional memory usage by the drivers.

Even though we can restore the ETM config with the config from the driver, we
still need to save/restore the state of non-config data such as counters (TRCCNTVRn)
that would get otherwise get lost.

Thanks,

Andrew Murray

> 
> Regards
> 
> Mike
> 
> 
> > -----Original Message-----
> > From: CoreSight <coresight-bounces@lists.linaro.org> On Behalf Of Andrew
> > Murray
> > Sent: 30 July 2019 22:46
> > To: Mathieu Poirier <mathieu.poirier@linaro.org>
> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>;
> > coresight@lists.linaro.org; Sudeep Holla <Sudeep.Holla@arm.com>; linux-
> > arm-kernel@lists.infradead.org; Mike Leach <mike.leach@linaro.org>
> > Subject: Re: [PATCH v4 5/6] coresight: etm4x: save/restore state across CPU
> > low power states
> > 
> > On Tue, Jul 30, 2019 at 03:16:33PM -0600, Mathieu Poirier wrote:
> > > On Tue, Jul 30, 2019 at 01:51:56PM +0100, Andrew Murray 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).
> > > >
> > > > We avoid saving the hardware state when coresight isn't in use to
> > > > reduce PM latency - we can't determine this by reading the claim
> > > > tags (TRCCLAIMCLR) as these are 'trace' registers which need power
> > > > and clocking, something we can't easily provide in the PM context.
> > > > Therefore we rely on the existing drvdata->mode internal state that
> > > > is set when self-hosted coresight is used (and powered).
> > > >
> > > > As we do not have a simple way of determining if an external agent
> > > > is using coresight, we don't save/restore for this use case.
> > > >
> > > > Signed-off-by: Andrew Murray <andrew.murray@arm.com>
> > > > ---
> > > >  drivers/hwtracing/coresight/coresight-etm4x.c | 322
> > > > ++++++++++++++++++  drivers/hwtracing/coresight/coresight-etm4x.h |
> > > > 64 ++++
> > > >  2 files changed, 386 insertions(+)
> > > >
> > > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c
> > > > b/drivers/hwtracing/coresight/coresight-etm4x.c
> > > > index a128b5063f46..30f118792289 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, 0444);
> > > > +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 +1104,294
> > @@
> > > > 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;
> > > > +	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);
> > > > +
> > > > +	state->trcpdcr = readl(drvdata->base + TRCPDCR);
> > > > +
> > > > +	/* 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.
> > > > +	 */
> > > > +	writel_relaxed((state->trcpdcr & ~TRCPDCR_PU),
> > > > +			drvdata->base + TRCPDCR);
> > > > +
> > > > +out:
> > > > +	CS_LOCK(drvdata->base);
> > > > +	return ret;
> > > > +}
> > > > +
> > > > +static void etm4_cpu_restore(struct etmv4_drvdata *drvdata) {
> > > > +	int i;
> > > > +	struct etmv4_save_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);
> > > > +
> > > > +	writel_relaxed(state->trcpdcr, drvdata->base + TRCPDCR);
> > > > +
> > > > +	drvdata->state_needs_restore = false;
> > > > +
> > > > +	/*
> > > > +	 * 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 (!drvdata->save_state)
> > > > +		return NOTIFY_OK;
> > >
> > > The problem here is that if no memory was allocated for ->save_state
> > > at boot time and someone does:
> > >         $ echo 1 >
> > > /sys/module/coresight_etm4x/parameters/pm_save_enable
> > >
> > > then they will be mislead in thinking that save/restore operations are
> > > taking place.  To avoid the problem I suggest to use module_param_cb()
> > > where memory can be allocated and freed as the functionality is requested
> > by users.
> > 
> > Actually notice the permissions of pm_save_enable:
> > 
> > > > +module_param(pm_save_enable, int, 0444);
> > 
> > I changed this to be readonly after boot. I initially started down the track of
> > module_param_cb, but allocating memory ahead of when it is needed was
> > slightly complex as the module_param_cb callback doesn't have drvdata and
> > so you'd have to figure out which of the etmdrvdata's to allocate for
> > (perhaps all those that are not NULL). You'd also have to allocate on probe as
> > well.
> > 
> > Besides the benefit of changing the param via sysfs for testing, I'm not sure
> > that this is all that useful to anyone - especially as we currently don't support
> > save/restore for external debug. Unless there are potential coresight users
> > that don't have the ability to change the kernel command line or device tree?
> > 
> > Thanks,
> > 
> > Andrew Murray
> > 
> > >
> > > Thanks,
> > > Mathieu
> > >
> > > > +
> > > > +	if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
> > > > +		return NOTIFY_BAD;
> > > > +
> > > > +	switch (cmd) {
> > > > +	case CPU_PM_ENTER:
> > > > +		/* save the state if self-hosted coresight is in use */
> > > > +		if (local_read(&drvdata->mode))
> > > > +			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 +1408,15 @@ static int etm4_probe(struct amba_device
> > > > *adev, const struct amba_id *id)
> > > >
> > > >  	dev_set_drvdata(dev, drvdata);
> > > >
> > > > +	if (pm_save_enable == PARAM_PM_SAVE_ALWAYS ||
> > > > +	    (pm_save_enable == PARAM_PM_SAVE_FIRMWARE &&
> > > > +	     etm4_needs_save_restore(dev))) {
> > > > +		drvdata->save_state = devm_kmalloc(dev,
> > > > +				sizeof(struct etmv4_save_state),
> > GFP_KERNEL);
> > > > +		if (!drvdata->save_state)
> > > > +			return -ENOMEM;
> > > > +	}
> > > > +
> > > >  	/* Validity for the resource is already checked by the AMBA core */
> > > >  	base = devm_ioremap_resource(dev, res);
> > > >  	if (IS_ERR(base))
> > > > @@ -1135,6 +1451,10 @@ 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();
> > > > @@ -1185,6 +1505,8 @@ 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_STARTI
> > NG);
> > > >  		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..546d790cb01b 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 +282,65 @@ 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];
> > > > +
> > > > +	u32	trcpdcr;
> > > > +};
> > > > +
> > > >  /**
> > > >   * struct etm4_drvdata - specifics associated to an ETM component
> > > >   * @base:       Memory mapped base address for this component.
> > > > @@ -336,6 +396,8 @@ 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
> > > > + * @state_needs_restore: True when there is context to restore
> > > > + after PM exit
> > > >   */
> > > >  struct etmv4_drvdata {
> > > >  	void __iomem			*base;
> > > > @@ -381,6 +443,8 @@ 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 */
> > > > --
> > > > 2.21.0
> > > >
> > _______________________________________________
> > CoreSight mailing list
> > CoreSight@lists.linaro.org
> > https://lists.linaro.org/mailman/listinfo/coresight

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