linux-kernel - [PATCH v2 06/12] coresight-replicator: Update management interface for CPU-bound devices

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Message-Id: <20251218-cpu_cluster_component_pm-v2-6-2335a6ae62a0@oss.qualcomm.com>
Date: Thu, 18 Dec 2025 00:09:46 -0800
From: Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        James Clark <james.clark@...aro.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...ux.dev>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: kernel@....qualcomm.com, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>,
        maulik.shah@....qualcomm.com
Subject: [PATCH v2 06/12] coresight-replicator: Update management interface
 for CPU-bound devices

Standard system replicators allow direct register access from any CPU.
However, replicators associated with specific CPU clusters share the
cluster's power domain and require access via a CPU within that domain.

Replace the standard `coresight_simple_reg*` accessors with custom
handlers (`coresight_replicator_reg*`) to support these devices:
- For cluster-bound replicators (indicated by `supported_cpus`), use
  `smp_call_function_single()` to read registers on an associated CPU.
- For standard replicators, retain the direct access behavior.

This ensures correct operation for per-cluster replicators while
maintaining compatibility for existing system-level devices.

Signed-off-by: Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
---
 drivers/hwtracing/coresight/coresight-replicator.c | 61 +++++++++++++++++++++-
 1 file changed, 59 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
index f8d13894098f1e414fb0da8d6eeb1da4f0d55a8c..a9f22d0e15de21aa06c8d1e193e5db06091efd75 100644
--- a/drivers/hwtracing/coresight/coresight-replicator.c
+++ b/drivers/hwtracing/coresight/coresight-replicator.c
@@ -58,6 +58,7 @@ struct replicator_drvdata {
 struct replicator_smp_arg {
 	struct replicator_drvdata *drvdata;
 	int outport;
+	u32 offset;
 	int rc;
 };
 
@@ -286,9 +287,65 @@ static const struct coresight_ops replicator_cs_ops = {
 	.link_ops	= &replicator_link_ops,
 };
 
+static void replicator_read_register_smp_call(void *info)
+{
+	struct replicator_smp_arg *arg = info;
+
+	arg->rc = readl_relaxed(arg->drvdata->base + arg->offset);
+}
+
+static ssize_t coresight_replicator_reg32_show(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	struct replicator_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct cs_off_attribute *cs_attr = container_of(attr, struct cs_off_attribute, attr);
+	unsigned long flags;
+	struct replicator_smp_arg arg = { 0 };
+	u32 val;
+	int ret, cpu;
+
+	pm_runtime_get_sync(dev->parent);
+
+	if (!drvdata->supported_cpus) {
+		raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+		val = readl_relaxed(drvdata->base + cs_attr->off);
+		raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+	} else {
+		arg.drvdata = drvdata;
+		arg.offset = cs_attr->off;
+		for_each_cpu(cpu, drvdata->supported_cpus) {
+			ret = smp_call_function_single(cpu,
+						       replicator_read_register_smp_call,
+						       &arg, 1);
+			if (!ret)
+				break;
+		}
+		if (!ret) {
+			val = arg.rc;
+		} else {
+			pm_runtime_put_sync(dev->parent);
+			return ret;
+		}
+	}
+
+	pm_runtime_put_sync(dev->parent);
+
+	return sysfs_emit(buf, "0x%x\n", val);
+}
+
+#define coresight_replicator_reg32(name, offset)				\
+	(&((struct cs_off_attribute[]) {				\
+	   {								\
+		__ATTR(name, 0444, coresight_replicator_reg32_show, NULL),	\
+		offset							\
+	   }								\
+	})[0].attr.attr)
+
 static struct attribute *replicator_mgmt_attrs[] = {
-	coresight_simple_reg32(idfilter0, REPLICATOR_IDFILTER0),
-	coresight_simple_reg32(idfilter1, REPLICATOR_IDFILTER1),
+	coresight_replicator_reg32(idfilter0, REPLICATOR_IDFILTER0),
+	coresight_replicator_reg32(idfilter1, REPLICATOR_IDFILTER1),
 	NULL,
 };
 

-- 
2.34.1