linux-kernel - [PATCH v2 19/28] coresight: cti: Introduce CS_MODE

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Message-Id: <20250701-arm_cs_pm_fix_v3-v2-19-23ebb864fcc1@arm.com>
Date: Tue, 01 Jul 2025 15:53:44 +0100
From: Leo Yan <leo.yan@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>, 
 Levi Yun <yeoreum.yun@....com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Yabin Cui <yabinc@...gle.com>, Keita Morisaki <keyz@...gle.com>, 
 Yuanfang Zhang <quic_yuanfang@...cinc.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Leo Yan <leo.yan@....com>
Subject: [PATCH v2 19/28] coresight: cti: Introduce CS_MODE_DEBUG mode

Introduce a new CS_MODE_DEBUG mode to indicate that a device is being
used for debugging purposes, e.g, if a system enables CTI for debugging
but not for hardware trace

Update ETM4x driver to mute compiler warnings for the newly added mode.

Signed-off-by: Leo Yan <leo.yan@....com>
---
 drivers/hwtracing/coresight/coresight-cti-sysfs.c  | 2 +-
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 2 ++
 include/linux/coresight.h                          | 9 +++++----
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
index 572b80ee96fbf18ec8cf9abc30d109a676dfbc5d..3e0039f75f5aad104cb86561bf37971c7dc4e408 100644
--- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
@@ -112,7 +112,7 @@ static ssize_t enable_store(struct device *dev,
 		ret = pm_runtime_resume_and_get(dev->parent);
 		if (ret)
 			return ret;
-		ret = cti_enable(drvdata->csdev, CS_MODE_SYSFS, NULL);
+		ret = cti_enable(drvdata->csdev, CS_MODE_DEBUG, NULL);
 		if (ret)
 			pm_runtime_put(dev->parent);
 	} else {
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index d71ac055c3d0b74053279a86ede7e5592f2b2909..93ae8590ae2459db317f6367b6cffbf658b0e2f2 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -932,6 +932,7 @@ static int etm4_enable(struct coresight_device *csdev, struct perf_event *event,
 	case CS_MODE_PERF:
 		ret = etm4_enable_perf(csdev, event, path);
 		break;
+	case CS_MODE_DEBUG:
 	default:
 		ret = -EINVAL;
 	}
@@ -1130,6 +1131,7 @@ static void etm4_disable(struct coresight_device *csdev,
 	mode = coresight_get_mode(csdev);
 
 	switch (mode) {
+	case CS_MODE_DEBUG:
 	case CS_MODE_DISABLED:
 		break;
 	case CS_MODE_SYSFS:
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 4d5c07b7ddc67991a3871851fe45463f92bd32c8..f52e834640b72534ea83ab223aae7544b195bbaa 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -253,10 +253,10 @@ struct coresight_trace_id_map {
  *		by @coresight_ops.
  * @access:	Device i/o access abstraction for this device.
  * @dev:	The device entity associated to this component.
- * @mode:	The device mode, i.e sysFS, Perf or disabled. This is actually
- *		an 'enum cs_mode' but stored in an atomic type. Access is always
- *		through atomic APIs, ensuring SMP-safe synchronisation between
- *		racing from sysFS and Perf mode. A compare-and-exchange
+ * @mode:	The device mode, i.e sysFS, Perf, debug or disabled. This is
+ *		actually an 'enum cs_mode' but stored in an atomic type. Access
+ *		is always through atomic APIs, ensuring SMP-safe synchronisation
+ *		between racing from sysFS and Perf mode. A compare-and-exchange
  *		operation is done to atomically claim one mode or the other.
  * @refcnt:	keep track of what is in use. Only access this outside of the
  *		device's spinlock when the coresight_mutex held and mode ==
@@ -344,6 +344,7 @@ enum cs_mode {
 	CS_MODE_DISABLED,
 	CS_MODE_SYSFS,
 	CS_MODE_PERF,
+	CS_MODE_DEBUG,
 };
 
 #define coresight_ops(csdev)	csdev->ops

-- 
2.34.1