linux-kernel - [RFC PATCH v3 7/7] coresight: etm4x: Configure ETM to trigger on panic

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Date:   Mon, 4 Sep 2023 10:35:47 +0530
From:   Linu Cherian <lcherian@...vell.com>
To:     <suzuki.poulose@....com>, <mike.leach@...aro.org>,
        <james.clark@....com>, <leo.yan@...aro.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <coresight@...ts.linaro.org>, <linux-kernel@...r.kernel.org>,
        <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <conor+dt@...nel.org>, <devicetree@...r.kernel.org>,
        <sgoutham@...vell.com>, <gcherian@...vell.com>,
        Linu Cherian <lcherian@...vell.com>
Subject: [RFC PATCH v3 7/7] coresight: etm4x: Configure ETM to trigger on panic

Configure ETM to generate a trigger on Ext out [0] on panic.
This is achieved by configuring a single address comparator
with the address of "panic" and by configuring Ext out [0] to
trigger on the comparator event.

This trigger can be used by the sinks to stop capture on panic.

Signed-off-by: Linu Cherian <lcherian@...vell.com>
---
 .../coresight/coresight-etm4x-core.c          | 17 +++++++++---
 drivers/hwtracing/coresight/coresight-etm4x.h | 26 +++++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 7c65d152aebb..423934efcd9d 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -62,6 +62,7 @@ static void etm4_set_default_config(struct etmv4_config *config);
 static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
 				  struct perf_event *event);
 static u64 etm4_get_access_type(struct etmv4_config *config);
+static u64 etm4_get_comparator_access_type(struct etmv4_config *config);
 
 static enum cpuhp_state hp_online;
 
@@ -1291,9 +1292,8 @@ static void etm4_set_victlr_access(struct etmv4_config *config)
 
 static void etm4_set_default_config(struct etmv4_config *config)
 {
-	/* disable all events tracing */
-	config->eventctrl0 = 0x0;
-	config->eventctrl1 = 0x0;
+	int rselector = 2; /* 0 and 1 are reserved */
+	int comp_idx = 0;
 
 	/* disable stalling */
 	config->stall_ctrl = 0x0;
@@ -1309,6 +1309,17 @@ static void etm4_set_default_config(struct etmv4_config *config)
 
 	/* TRCVICTLR::EXLEVEL_NS:EXLEVELS: Set kernel / user filtering */
 	etm4_set_victlr_access(config);
+
+	/* Configure the comparator with kernel panic address */
+	config->addr_val[comp_idx] = (u64)panic;
+	config->addr_acc[comp_idx] = etm4_get_comparator_access_type(config);
+	config->addr_type[comp_idx] = ETM_ADDR_TYPE_STOP;
+	config->res_ctrl[rselector] = ETM_RESGRP_SADDRCMP << 16 | BIT(comp_idx);
+
+	/* Connect external output [0] with comparator out */
+	config->eventctrl0 = 0x0 << 7 | rselector;
+
+	config->eventctrl1 = 0x0;
 }
 
 static u64 etm4_get_ns_access_type(struct etmv4_config *config)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 27c8a9901868..6ac5d5ee1877 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -612,6 +612,32 @@
 #define ETM_CNTR_MAX_VAL		0xFFFF
 #define ETM_TRACEID_MASK		0x3f
 
+/* ETM resource group encoding */
+#define ETM_RESGRP_EXTIN		0x0
+#define ETM_RESGRP_PECMP		0x1
+#define ETM_RESGRP_CNTRSEQ		0x2
+#define ETM_RESGRP_SSCMP		0x3
+#define ETM_RESGRP_SADDRCMP		0x4
+#define ETM_RESGRP_ADDRRANGECMP		0x5
+#define ETM_RESGRP_CIDCMP		0x6
+#define ETM_RESGRP_VCIDCMP		0x7
+
+#define ETM_EXTIN_0			0x0
+
+
+/* ETM resource group encoding */
+#define ETM_RESGRP_EXTIN		0x0
+#define ETM_RESGRP_PECMP		0x1
+#define ETM_RESGRP_CNTRSEQ		0x2
+#define ETM_RESGRP_SSCMP		0x3
+#define ETM_RESGRP_SADDRCMP		0x4
+#define ETM_RESGRP_ADDRRANGECMP		0x5
+#define ETM_RESGRP_CIDCMP		0x6
+#define ETM_RESGRP_VCIDCMP		0x7
+
+#define ETM_EXTIN_0			0x0
+
+
 /* ETMv4 programming modes */
 #define ETM_MODE_EXCLUDE		BIT(0)
 #define ETM_MODE_LOAD			BIT(1)
-- 
2.41.0