Commit 937d3f58 authored by Suzuki K Poulose's avatar Suzuki K Poulose Committed by Mathieu Poirier
Browse files

coresight: etm4x: Save restore TRFCR_EL1 



When the CPU enters a low power mode, the TRFCR_EL1 contents could be
reset. Thus we need to save/restore the TRFCR_EL1 along with the ETM4x
registers to allow the tracing.

The TRFCR related helpers are in a new header file, as we need to use
them for TRBE in the later patches.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210914102641.1852544-2-suzuki.poulose@arm.com


[Fixed cosmetic details]
Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
parent 8c60acbc

drivers/hwtracing/coresight/coresight-etm4x-core.c

+31 −12
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#include "coresight-etm4x.h"

#include "coresight-etm-perf.h"

#include "coresight-etm4x-cfg.h"

#include "coresight-self-hosted-trace.h"

#include "coresight-syscfg.h"



static int boot_enable;
@@ -1011,7 +1012,7 @@ static void cpu_enable_tracing(struct etmv4_drvdata *drvdata) 
	if (is_kernel_in_hyp_mode())

		trfcr |= TRFCR_EL2_CX;



	write_sysreg_s(trfcr, SYS_TRFCR_EL1);

	write_trfcr(trfcr);

}



static void etm4_init_arch_data(void *info)
@@ -1554,7 +1555,7 @@ static void etm4_init_trace_id(struct etmv4_drvdata *drvdata) 
	drvdata->trcid = coresight_get_trace_id(drvdata->cpu);

}



static int etm4_cpu_save(struct etmv4_drvdata *drvdata)

static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)

{

	int i, ret = 0;

	struct etmv4_save_state *state;
@@ -1693,7 +1694,23 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata) 
	return ret;

}



static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)

static int etm4_cpu_save(struct etmv4_drvdata *drvdata)

{

	int ret = 0;



	/* Save the TRFCR irrespective of whether the ETM is ON */

	if (drvdata->trfc)

		drvdata->save_trfcr = read_trfcr();

	/*

	 * Save and restore the ETM Trace registers only if

	 * the ETM is active.

	 */

	if (local_read(&drvdata->mode) && drvdata->save_state)

		ret = __etm4_cpu_save(drvdata);

	return ret;

}



static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)

{

	int i;

	struct etmv4_save_state *state = drvdata->save_state;
@@ -1789,6 +1806,14 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata) 
	etm4_cs_lock(drvdata, csa);

}



static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)

{

	if (drvdata->trfc)

		write_trfcr(drvdata->save_trfcr);

	if (drvdata->state_needs_restore)

		__etm4_cpu_restore(drvdata);

}



static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,

			      void *v)

{
@@ -1800,22 +1825,16 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd, 


	drvdata = etmdrvdata[cpu];



	if (!drvdata->save_state)

		return NOTIFY_OK;



	if (WARN_ON_ONCE(drvdata->cpu != cpu))

		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:

		if (drvdata->state_needs_restore)

		etm4_cpu_restore(drvdata);

		break;

	default:

drivers/hwtracing/coresight/coresight-etm4x.h

+2 −0
Original line number Diff line number Diff line
@@ -921,6 +921,7 @@ struct etmv4_save_state { 
 * @lpoverride:	If the implementation can support low-power state over.

 * @trfc:	If the implementation supports Arm v8.4 trace filter controls.

 * @config:	structure holding configuration parameters.

 * @save_trfcr:	Saved TRFCR_EL1 register during a CPU PM event.

 * @save_state:	State to be preserved across power loss

 * @state_needs_restore: True when there is context to restore after PM exit

 * @skip_power_up: Indicates if an implementation can skip powering up
@@ -973,6 +974,7 @@ struct etmv4_drvdata { 
	bool				lpoverride;

	bool				trfc;

	struct etmv4_config		config;

	u64				save_trfcr;

	struct etmv4_save_state		*save_state;

	bool				state_needs_restore;

	bool				skip_power_up;

drivers/hwtracing/coresight/coresight-self-hosted-trace.h

0 → 100644
+24 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Arm v8 Self-Hosted trace support.

 *

 * Copyright (C) 2021 ARM Ltd.

 */



#ifndef __CORESIGHT_SELF_HOSTED_TRACE_H

#define __CORESIGHT_SELF_HOSTED_TRACE_H



#include <asm/sysreg.h>



static inline u64 read_trfcr(void)

{

	return read_sysreg_s(SYS_TRFCR_EL1);

}



static inline void write_trfcr(u64 val)

{

	write_sysreg_s(val, SYS_TRFCR_EL1);

	isb();

}



#endif /*  __CORESIGHT_SELF_HOSTED_TRACE_H */