[PATCH 08/12] coresight-tmc-etf: Refactor enable function for CPU cluster ETF support

[Yuanfang Zhang <yuanfang.zhang@oss.qualcomm.com>]

CPU cluster TMC instances share the cluster's power domain, so register
access must occur on a CPU that keeps the domain powered. To ensure safe
ETF enable sequences on such devices, split tmc_etf/etb_enable_hw function
into two variants:

 - tmc_etf/etb_enable_hw_local: replaces the old tmc_etf/etb_enable_hw for
   normal ETF cases
 - tmc_etf/etb_enable_hw_smp_call: executes CPU cluster ETF enable on a CPU
   within the cluster via smp_call_function_single

Also add a check to ensure the current CPU belongs to the cluster before
calling tmc_etb_enable_hw_local for CPU cluster ETF.

Signed-off-by: Yuanfang Zhang <yuanfang.zhang@oss.qualcomm.com>
---
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 86 ++++++++++++++++++++++---
 1 file changed, 76 insertions(+), 10 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 0f45ab5e5249933ce7059dfee7fe7376ab33ed2d..b8a1c10d4b4c49144449b33f26710cf11713b338 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -47,7 +47,7 @@ static int __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
 	return rc;
 }
 
-static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
+static int tmc_etb_enable_hw_local(struct tmc_drvdata *drvdata)
 {
 	int rc = coresight_claim_device(drvdata->csdev);
 
@@ -60,6 +60,36 @@ static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
 	return rc;
 }
 
+struct tmc_smp_arg {
+	struct tmc_drvdata *drvdata;
+	int rc;
+};
+
+static void tmc_etb_enable_hw_smp_call(void *info)
+{
+	struct tmc_smp_arg *arg = info;
+
+	arg->rc = tmc_etb_enable_hw_local(arg->drvdata);
+}
+
+static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
+{
+	int cpu, ret;
+	struct tmc_smp_arg arg = { 0 };
+
+	if (!drvdata->cpumask)
+		return tmc_etb_enable_hw_local(drvdata);
+
+	arg.drvdata = drvdata;
+	for_each_cpu(cpu, drvdata->cpumask) {
+		ret = smp_call_function_single(cpu,
+					       tmc_etb_enable_hw_smp_call, &arg, 1);
+		if (!ret)
+			return arg.rc;
+	}
+	return ret;
+}
+
 static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
 {
 	char *bufp;
@@ -130,7 +160,7 @@ static int __tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
 	return rc;
 }
 
-static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
+static int tmc_etf_enable_hw_local(struct tmc_drvdata *drvdata)
 {
 	int rc = coresight_claim_device(drvdata->csdev);
 
@@ -143,6 +173,32 @@ static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
 	return rc;
 }
 
+static void tmc_etf_enable_hw_smp_call(void *info)
+{
+	struct tmc_smp_arg *arg = info;
+
+	arg->rc = tmc_etf_enable_hw_local(arg->drvdata);
+}
+
+static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
+{
+	int cpu, ret;
+	struct tmc_smp_arg arg = { 0 };
+
+	if (!drvdata->cpumask)
+		return tmc_etf_enable_hw_local(drvdata);
+
+	arg.drvdata = drvdata;
+
+	for_each_cpu(cpu, drvdata->cpumask) {
+		ret = smp_call_function_single(cpu,
+					       tmc_etf_enable_hw_smp_call, &arg, 1);
+		if (!ret)
+			return arg.rc;
+	}
+	return ret;
+}
+
 static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
 {
 	struct coresight_device *csdev = drvdata->csdev;
@@ -228,7 +284,11 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
 		used = true;
 		drvdata->buf = buf;
 	}
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
 	ret = tmc_etb_enable_hw(drvdata);
+
+	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 	if (!ret) {
 		coresight_set_mode(csdev, CS_MODE_SYSFS);
 		csdev->refcnt++;
@@ -290,7 +350,10 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
 			break;
 		}
 
-		ret  = tmc_etb_enable_hw(drvdata);
+		if (drvdata->cpumask && !cpumask_test_cpu(smp_processor_id(), drvdata->cpumask))
+			break;
+
+		ret  = tmc_etb_enable_hw_local(drvdata);
 		if (!ret) {
 			/* Associate with monitored process. */
 			drvdata->pid = pid;
@@ -374,19 +437,22 @@ static int tmc_enable_etf_link(struct coresight_device *csdev,
 		return -EBUSY;
 	}
 
-	if (csdev->refcnt == 0) {
+	if (csdev->refcnt == 0)
+		first_enable = true;
+
+	if (!first_enable)
+		csdev->refcnt++;
+
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	if (first_enable) {
 		ret = tmc_etf_enable_hw(drvdata);
 		if (!ret) {
 			coresight_set_mode(csdev, CS_MODE_SYSFS);
-			first_enable = true;
+			csdev->refcnt++;
+			dev_dbg(&csdev->dev, "TMC-ETF enabled\n");
 		}
 	}
-	if (!ret)
-		csdev->refcnt++;
-	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
-	if (first_enable)
-		dev_dbg(&csdev->dev, "TMC-ETF enabled\n");
 	return ret;
 }
 

-- 
2.34.1