linux-kernel - [PATCH 26/31] coresight: etm4x: Run arch feature detection on the CPU

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Date:   Mon,  1 Feb 2021 11:13:46 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 26/31] coresight: etm4x: Run arch feature detection on the CPU

From: Suzuki K Poulose <suzuki.poulose@....com>

As we are about to add support for system register based devices,
we don't get an AMBA pid. So, the detection code could check
the system registers running on the CPU to check for the architecture
specific features. Thus we move the arch feature detection to
run on the CPU. We cannot always read the PID from the HW, as the
PID could be overridden by DT for broken devices. So, use the
PID from AMBA layer if available.

Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: liuqi115@...wei.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Link: https://lore.kernel.org/r/20210110224850.1880240-25-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index c3e458af618a..fc26ecbc2d87 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -60,6 +60,7 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
 static enum cpuhp_state hp_online;
 
 struct etm4_init_arg {
+	unsigned int		pid;
 	struct etmv4_drvdata	*drvdata;
 	struct csdev_access	*csa;
 };
@@ -884,6 +885,8 @@ static void etm4_init_arch_data(void *info)
 	etm4_os_unlock_csa(drvdata, csa);
 	etm4_cs_unlock(drvdata, csa);
 
+	etm4_check_arch_features(drvdata, init_arg->pid);
+
 	/* find all capabilities of the tracing unit */
 	etmidr0 = etm4x_relaxed_read32(csa, TRCIDR0);
 
@@ -1750,6 +1753,7 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
 
 	init_arg.drvdata = drvdata;
 	init_arg.csa = &desc.access;
+	init_arg.pid = etm_pid;
 
 	if (smp_call_function_single(drvdata->cpu,
 				etm4_init_arch_data,  &init_arg, 1))
@@ -1794,8 +1798,6 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
 		drvdata->boot_enable = true;
 	}
 
-	etm4_check_arch_features(drvdata, etm_pid);
-
 	return 0;
 }
 
-- 
2.25.1