linux-kernel - [PATCH 2/2] soc: qcom: pmic_glink: Add support for subsystem restart (SSR)

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Message-Id: <20250624225535.2013141-3-anjelique.melendez@oss.qualcomm.com>
Date: Tue, 24 Jun 2025 15:55:35 -0700
From: Anjelique Melendez <anjelique.melendez@....qualcomm.com>
To: andersson@...nel.org, konradybcio@...nel.org, robh@...nel.org,
        krzk+dt@...nel.org, conor+dt@...nel.org
Cc: dmitry.baryshkov@....qualcomm.com, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] soc: qcom: pmic_glink: Add support for subsystem restart (SSR)

Add support for PMIC Glink clients to receive notificiation when
the subsystem goes down and comes up again.

Signed-off-by: Anjelique Melendez <anjelique.melendez@....qualcomm.com>
---
 drivers/soc/qcom/pmic_glink.c | 43 +++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index 0a6d325b195c..5121f19d63e5 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (c) 2019-2020, The Linux Foundation. All rights reserved.
  * Copyright (c) 2022, Linaro Ltd
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
  */
 #include <linux/auxiliary_bus.h>
 #include <linux/cleanup.h>
@@ -9,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/remoteproc/qcom_rproc.h>
 #include <linux/rpmsg.h>
 #include <linux/slab.h>
 #include <linux/soc/qcom/pdr.h>
@@ -39,10 +41,14 @@ struct pmic_glink {
 	struct mutex state_lock;
 	unsigned int client_state;
 	unsigned int pdr_state;
+	unsigned int ssr_state;
 
 	/* serializing clients list updates */
 	spinlock_t client_lock;
 	struct list_head clients;
+
+	struct notifier_block ssr_nb;
+	void *ssr_handle;
 };
 
 static struct pmic_glink *__pmic_glink;
@@ -205,10 +211,12 @@ static void pmic_glink_state_notify_clients(struct pmic_glink *pg)
 	unsigned long flags;
 
 	if (pg->client_state != SERVREG_SERVICE_STATE_UP) {
-		if (pg->pdr_state == SERVREG_SERVICE_STATE_UP && pg->ept)
+		if ((pg->pdr_state == SERVREG_SERVICE_STATE_UP ||
+		     pg->ssr_state == QCOM_SSR_AFTER_POWERUP) && pg->ept)
 			new_state = SERVREG_SERVICE_STATE_UP;
 	} else {
-		if (pg->pdr_state == SERVREG_SERVICE_STATE_DOWN || !pg->ept)
+		if (pg->pdr_state == SERVREG_SERVICE_STATE_DOWN ||
+		    pg->ssr_state == QCOM_SSR_BEFORE_SHUTDOWN || !pg->ept)
 			new_state = SERVREG_SERVICE_STATE_DOWN;
 	}
 
@@ -231,6 +239,18 @@ static void pmic_glink_pdr_callback(int state, char *svc_path, void *priv)
 	pmic_glink_state_notify_clients(pg);
 }
 
+static int pmic_glink_ssr_callback(struct notifier_block *nb, unsigned long code, void *data)
+{
+	struct pmic_glink *pg = container_of(nb, struct pmic_glink, ssr_nb);
+
+	mutex_lock(&pg->state_lock);
+	pg->ssr_state = code;
+
+	pmic_glink_state_notify_clients(pg);
+	mutex_unlock(&pg->state_lock);
+	return 0;
+}
+
 static int pmic_glink_rpmsg_probe(struct rpmsg_device *rpdev)
 {
 	struct pmic_glink *pg;
@@ -281,6 +301,7 @@ static struct rpmsg_driver pmic_glink_rpmsg_driver = {
 static int pmic_glink_probe(struct platform_device *pdev)
 {
 	const unsigned long *match_data;
+	const char *subsys_name = NULL;
 	struct pdr_service *service;
 	struct pmic_glink *pg;
 	int ret;
@@ -333,6 +354,22 @@ static int pmic_glink_probe(struct platform_device *pdev)
 		goto out_release_aux_devices;
 	}
 
+	if (device_property_present(&pdev->dev, "qcom,subsys-name")) {
+		device_property_read_string(&pdev->dev, "qcom,subsys-name", &subsys_name);
+		if (!subsys_name) {
+			ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->ssr_handle),
+					"failed to read subsys_name string from dt\n");
+			goto out_release_aux_devices;
+		}
+		pg->ssr_nb.notifier_call = pmic_glink_ssr_callback;
+		pg->ssr_handle = qcom_register_ssr_notifier(subsys_name, &pg->ssr_nb);
+		if (IS_ERR(pg->ssr_handle)) {
+			ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->ssr_handle),
+					"failed adding ssr notifier\n");
+			goto out_release_aux_devices;
+		}
+	}
+
 	mutex_lock(&__pmic_glink_lock);
 	__pmic_glink = pg;
 	mutex_unlock(&__pmic_glink_lock);
@@ -360,6 +397,8 @@ static void pmic_glink_remove(struct platform_device *pdev)
 
 	pdr_handle_release(pg->pdr);
 
+	if (pg->ssr_handle)
+		qcom_unregister_ssr_notifier(pg->ssr_handle, &pg->ssr_nb);
 	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_BATT))
 		pmic_glink_del_aux_device(pg, &pg->ps_aux);
 	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_ALTMODE))
-- 
2.34.1