linux-kernel - [PATCH 6/7] remoteproc: qcom_q6v5_pas: Add hwspinlock bust on stop

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Message-ID: <20240516-hwspinlock-bust-v1-6-47a90a859238@quicinc.com>
Date: Thu, 16 May 2024 15:58:24 -0700
From: Chris Lew <quic_clew@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Baolin Wang
	<baolin.wang@...ux.alibaba.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Ingo
 Molnar" <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Waiman Long
	<longman@...hat.com>, Boqun Feng <boqun.feng@...il.com>,
        Jonathan Corbet
	<corbet@....net>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring
	<robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Manivannan Sadhasivam
	<manivannan.sadhasivam@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>
CC: <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, Chris Lew <quic_clew@...cinc.com>,
        "Richard
 Maina" <quic_rmaina@...cinc.com>
Subject: [PATCH 6/7] remoteproc: qcom_q6v5_pas: Add hwspinlock bust on stop

From: Richard Maina <quic_rmaina@...cinc.com>

When remoteproc goes down unexpectedly this results in a state where any
acquired hwspinlocks will remain locked possibly resulting in deadlock.
In order to ensure all locks are freed we include a call to
hwspin_lock_bust() during remoteproc shutdown.

For qcom_q6v5_pas remoteprocs, each remoteproc has an assigned id that
is used to take the hwspinlock. Remoteproc should use this id to try and
bust the lock on remoteproc stop.

This edge case only occurs with q6v5_pas watchdog crashes. The error
fatal case has handling to clear the hwspinlock before the error fatal
interrupt is triggered.

Signed-off-by: Richard Maina <quic_rmaina@...cinc.com>
Signed-off-by: Chris Lew <quic_clew@...cinc.com>
---
 drivers/remoteproc/qcom_q6v5_pas.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
index 54d8005d40a3..57178fcb9aa3 100644
--- a/drivers/remoteproc/qcom_q6v5_pas.c
+++ b/drivers/remoteproc/qcom_q6v5_pas.c
@@ -10,6 +10,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/firmware.h>
+#include <linux/hwspinlock.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -52,6 +53,7 @@ struct adsp_data {
 	const char *ssr_name;
 	const char *sysmon_name;
 	int ssctl_id;
+	int hwlock_id;
 
 	int region_assign_idx;
 	int region_assign_count;
@@ -84,6 +86,9 @@ struct qcom_adsp {
 	bool decrypt_shutdown;
 	const char *info_name;
 
+	struct hwspinlock *hwlock;
+	int hwlock_id;
+
 	const struct firmware *firmware;
 	const struct firmware *dtb_firmware;
 
@@ -399,6 +404,12 @@ static int adsp_stop(struct rproc *rproc)
 	if (handover)
 		qcom_pas_handover(&adsp->q6v5);
 
+	if (adsp->hwlock) {
+		ret = hwspin_lock_bust(adsp->hwlock, adsp->hwlock_id);
+		if (ret)
+			dev_info(adsp->dev, "failed to bust hwspinlock\n");
+	}
+
 	return ret;
 }
 
@@ -684,6 +695,7 @@ static int adsp_probe(struct platform_device *pdev)
 	struct rproc *rproc;
 	const char *fw_name, *dtb_fw_name = NULL;
 	const struct rproc_ops *ops = &adsp_ops;
+	int hwlock_idx;
 	int ret;
 
 	desc = of_device_get_match_data(&pdev->dev);
@@ -736,6 +748,17 @@ static int adsp_probe(struct platform_device *pdev)
 		adsp->dtb_firmware_name = dtb_fw_name;
 		adsp->dtb_pas_id = desc->dtb_pas_id;
 	}
+
+	if (desc->hwlock_id) {
+		adsp->hwlock_id = desc->hwlock_id;
+		hwlock_idx = of_hwspin_lock_get_id(pdev->dev.of_node, 0);
+		if (hwlock_idx >= 0) {
+			adsp->hwlock = hwspin_lock_request_specific(hwlock_idx);
+			if (!adsp->hwlock)
+				dev_err(&pdev->dev, "failed to request hwspinlock\n");
+		}
+	}
+
 	platform_set_drvdata(pdev, adsp);
 
 	ret = device_init_wakeup(adsp->dev, true);
@@ -1196,6 +1219,7 @@ static const struct adsp_data sm8550_adsp_resource = {
 	.ssr_name = "lpass",
 	.sysmon_name = "adsp",
 	.ssctl_id = 0x14,
+	.hwlock_id = 3,
 };
 
 static const struct adsp_data sm8550_cdsp_resource = {
@@ -1216,6 +1240,7 @@ static const struct adsp_data sm8550_cdsp_resource = {
 	.ssr_name = "cdsp",
 	.sysmon_name = "cdsp",
 	.ssctl_id = 0x17,
+	.hwlock_id = 6,
 };
 
 static const struct adsp_data sm8550_mpss_resource = {
@@ -1236,6 +1261,7 @@ static const struct adsp_data sm8550_mpss_resource = {
 	.ssr_name = "mpss",
 	.sysmon_name = "modem",
 	.ssctl_id = 0x12,
+	.hwlock_id = 2,
 	.region_assign_idx = 2,
 	.region_assign_count = 1,
 	.region_assign_vmid = QCOM_SCM_VMID_MSS_MSA,
@@ -1275,6 +1301,7 @@ static const struct adsp_data sm8650_cdsp_resource = {
 	.ssr_name = "cdsp",
 	.sysmon_name = "cdsp",
 	.ssctl_id = 0x17,
+	.hwlock_id = 6,
 	.region_assign_idx = 2,
 	.region_assign_count = 1,
 	.region_assign_shared = true,
@@ -1299,6 +1326,7 @@ static const struct adsp_data sm8650_mpss_resource = {
 	.ssr_name = "mpss",
 	.sysmon_name = "modem",
 	.ssctl_id = 0x12,
+	.hwlock_id = 2,
 	.region_assign_idx = 2,
 	.region_assign_count = 3,
 	.region_assign_vmid = QCOM_SCM_VMID_MSS_MSA,

-- 
2.25.1