remoteproc: qcom: pas: Add late attach support for subsystems

Subsystems can be brought out of reset by entities such as bootloaders.
As the irq enablement could be later than subsystem bring up, the state
of subsystem should be checked by reading SMP2P bits.

A new qcom_pas_attach() function is introduced. if crash state is detected
for the subsystem, rproc_report_crash() is called. If the ready state is
detected meanwhile stop state is not detected, it will be marked as
"attached", otherwise it could be the early boot feature is not supported
by other entities or it has already been stopped. In above cases, the
state will be marked as RPROC_OFFLINE so that the PAS driver can load the
firmware and start the remoteproc.

Co-developed-by: Gokul Krishna Krishnakumar <gokul.krishnakumar@oss.qualcomm.com>
Signed-off-by: Gokul Krishna Krishnakumar <gokul.krishnakumar@oss.qualcomm.com>
Tested-by: Shawn Guo <shengchao.guo@oss.qualcomm.com>
Signed-off-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
Tested-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260623-knp-soccp-v7-5-1ec7bb5c9fec@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/remoteproc/qcom_common.h

@@ -68,6 +68,7 @@ struct qcom_sysmon *qcom_add_sysmon_subdev(struct rproc *rproc,
 					   int ssctl_instance);
 void qcom_remove_sysmon_subdev(struct qcom_sysmon *sysmon);
 bool qcom_sysmon_shutdown_acked(struct qcom_sysmon *sysmon);
+bool qcom_sysmon_shutdown_irq_state(struct qcom_sysmon *sysmon);
 #else
 static inline struct qcom_sysmon *qcom_add_sysmon_subdev(struct rproc *rproc,
 							 const char *name,
@@ -84,6 +85,11 @@ static inline bool qcom_sysmon_shutdown_acked(struct qcom_sysmon *sysmon)
 {
 	return false;
 }
+
+static inline bool qcom_sysmon_shutdown_irq_state(struct qcom_sysmon *sysmon)
+{
+	return false;
+}
 #endif
 
 #endif

drivers/remoteproc/qcom_q6v5.c

@@ -202,7 +202,8 @@ int qcom_q6v5_request_stop(struct qcom_q6v5 *q6v5, struct qcom_sysmon *sysmon)
 	q6v5->running = false;
 
 	/* Don't perform SMP2P dance if remote isn't running */
-	if (q6v5->rproc->state != RPROC_RUNNING || qcom_sysmon_shutdown_acked(sysmon))
+	if ((q6v5->rproc->state != RPROC_RUNNING && q6v5->rproc->state != RPROC_ATTACHED) ||
+	    qcom_sysmon_shutdown_acked(sysmon))
 		return 0;
 
 	qcom_smem_state_update_bits(q6v5->state,

drivers/remoteproc/qcom_q6v5_pas.c

@@ -60,6 +60,7 @@ struct qcom_pas_data {
 	int region_assign_count;
 	bool region_assign_shared;
 	int region_assign_vmid;
+	bool early_boot;
 };
 
 struct qcom_pas {
@@ -507,6 +508,67 @@ static unsigned long qcom_pas_panic(struct rproc *rproc)
 	return qcom_q6v5_panic(&pas->q6v5);
 }
 
+static int qcom_pas_attach(struct rproc *rproc)
+{
+	struct qcom_pas *pas = rproc->priv;
+	bool ready_state;
+	bool crash_state;
+	bool stop_state;
+	int ret;
+
+	pas->q6v5.handover_issued = true;
+	enable_irq(pas->q6v5.handover_irq);
+
+	pas->q6v5.running = true;
+	ret = irq_get_irqchip_state(pas->q6v5.fatal_irq,
+				    IRQCHIP_STATE_LINE_LEVEL, &crash_state);
+	if (ret)
+		goto disable_running;
+
+	if (crash_state) {
+		dev_err(pas->dev, "Subsystem has crashed before driver probe\n");
+		rproc_report_crash(rproc, RPROC_FATAL_ERROR);
+		ret = -EINVAL;
+		goto disable_running;
+	}
+
+	ret = irq_get_irqchip_state(pas->q6v5.stop_irq,
+				    IRQCHIP_STATE_LINE_LEVEL, &stop_state);
+	if (ret)
+		goto disable_running;
+
+	if (stop_state || qcom_sysmon_shutdown_irq_state(pas->sysmon)) {
+		dev_info(pas->dev, "Subsystem found stop state set. Falling back to start.\n");
+		goto unroll_attach;
+	}
+
+	ret = irq_get_irqchip_state(pas->q6v5.ready_irq,
+				    IRQCHIP_STATE_LINE_LEVEL, &ready_state);
+	if (ret)
+		goto disable_running;
+
+	if (unlikely(!ready_state)) {
+		/*
+		 * The bootloader may not support early boot, mark the state as
+		 * RPROC_OFFLINE so that the PAS driver can load the firmware and
+		 * start the remoteproc.
+		 */
+		dev_err(pas->dev, "Failed to get subsystem ready interrupt\n");
+		goto unroll_attach;
+	}
+
+	return 0;
+
+unroll_attach:
+	pas->rproc->state = RPROC_OFFLINE;
+	ret = -EINVAL;
+disable_running:
+	disable_irq(pas->q6v5.handover_irq);
+	pas->q6v5.running = false;
+
+	return ret;
+}
+
 static const struct rproc_ops qcom_pas_ops = {
 	.unprepare = qcom_pas_unprepare,
 	.start = qcom_pas_start,
@@ -515,6 +577,7 @@ static const struct rproc_ops qcom_pas_ops = {
 	.parse_fw = qcom_pas_parse_firmware,
 	.load = qcom_pas_load,
 	.panic = qcom_pas_panic,
+	.attach = qcom_pas_attach,
 };
 
 static const struct rproc_ops qcom_pas_minidump_ops = {
@@ -526,6 +589,7 @@ static const struct rproc_ops qcom_pas_minidump_ops = {
 	.load = qcom_pas_load,
 	.panic = qcom_pas_panic,
 	.coredump = qcom_pas_minidump,
+	.attach = qcom_pas_attach,
 };
 
 static int qcom_pas_init_clock(struct qcom_pas *pas)
@@ -852,6 +916,10 @@ static int qcom_pas_probe(struct platform_device *pdev)
 
 	pas->pas_ctx->use_tzmem = rproc->has_iommu;
 	pas->dtb_pas_ctx->use_tzmem = rproc->has_iommu;
+
+	if (desc->early_boot)
+		pas->rproc->state = RPROC_DETACHED;
+
 	ret = rproc_add(rproc);
 	if (ret)
 		goto remove_ssr_sysmon;

drivers/remoteproc/qcom_sysmon.c

@@ -736,6 +736,25 @@ bool qcom_sysmon_shutdown_acked(struct qcom_sysmon *sysmon)
 }
 EXPORT_SYMBOL_GPL(qcom_sysmon_shutdown_acked);
 
+bool qcom_sysmon_shutdown_irq_state(struct qcom_sysmon *sysmon)
+{
+	bool shutdown_state;
+	int ret;
+
+	if (!sysmon)
+		return false;
+
+	ret = irq_get_irqchip_state(sysmon->shutdown_irq,
+				    IRQCHIP_STATE_LINE_LEVEL, &shutdown_state);
+	if (ret) {
+		dev_warn(sysmon->dev, "failed to get shutdown_state: %d\n", ret);
+		return false;
+	}
+
+	return shutdown_state;
+}
+EXPORT_SYMBOL_GPL(qcom_sysmon_shutdown_irq_state);
+
 /**
  * sysmon_probe() - probe sys_mon channel
  * @rpdev:	rpmsg device handle