[PATCH v3] accel/qaic: Add support for PM callbacks

[Zack McKevitt <zachary.mckevitt@oss.qualcomm.com>]

From: Youssef Samir <youssef.abdulrahman@oss.qualcomm.com>

Add initial support for suspend and hibernation PM callbacks to QAIC.
The device can be suspended any time in which the data path is not
busy as queued I/O operations are lost on suspension and cannot be
resumed after suspend.

Signed-off-by: Youssef Samir <youssef.abdulrahman@oss.qualcomm.com>
Reviewed-by: Carl Vanderlip <carl.vanderlip@oss.qualcomm.com>
Signed-off-by: Zack McKevitt <zachary.mckevitt@oss.qualcomm.com>
---
Changes in v3:
- Update commit message to be more descriptive.
- Initialize return value to avoid returning uninitialized data in qaic_data_path_busy.
- Use modern PM macros to register callbacks and avoid checking for CONFIG_PM_SLEEP directly.
- Link to v2: https://lore.kernel.org/all/20251024162916.801196-1-youssef.abdulrahman@oss.qualcomm.com/

Changes in v2:
- Guard the pm callbacks with CONFIG_PM_SLEEP to fix openrisc build error
- Add __maybe_unused to helper functions used only in PM callbacks currently
- Link to v1: https://lore.kernel.org/all/20251022204005.3888195-1-youssef.abdulrahman@oss.qualcomm.com
---
 drivers/accel/qaic/qaic.h          |  2 +
 drivers/accel/qaic/qaic_drv.c      | 89 ++++++++++++++++++++++++++++++
 drivers/accel/qaic/qaic_timesync.c |  9 +++
 drivers/accel/qaic/qaic_timesync.h |  3 +
 4 files changed, 103 insertions(+)

diff --git a/drivers/accel/qaic/qaic.h b/drivers/accel/qaic/qaic.h
index 820d133236dd..2bfc4ce203c5 100644
--- a/drivers/accel/qaic/qaic.h
+++ b/drivers/accel/qaic/qaic.h
@@ -161,6 +161,8 @@ struct qaic_device {
 	struct mhi_device	*qts_ch;
 	/* Work queue for tasks related to MHI "QAIC_TIMESYNC" channel */
 	struct workqueue_struct	*qts_wq;
+	/* MHI "QAIC_TIMESYNC_PERIODIC" channel device */
+	struct mhi_device	*mqts_ch;
 	/* Head of list of page allocated by MHI bootlog device */
 	struct list_head        bootlog;
 	/* MHI bootlog channel device */
diff --git a/drivers/accel/qaic/qaic_drv.c b/drivers/accel/qaic/qaic_drv.c
index e162f4b8a262..1b5dc717a6c7 100644
--- a/drivers/accel/qaic/qaic_drv.c
+++ b/drivers/accel/qaic/qaic_drv.c
@@ -660,6 +660,92 @@ static const struct pci_error_handlers qaic_pci_err_handler = {
 	.reset_done = qaic_pci_reset_done,
 };
 
+static bool qaic_is_under_reset(struct qaic_device *qdev)
+{
+	int rcu_id;
+	bool ret;
+
+	rcu_id = srcu_read_lock(&qdev->dev_lock);
+	ret = qdev->dev_state != QAIC_ONLINE;
+	srcu_read_unlock(&qdev->dev_lock, rcu_id);
+	return ret;
+}
+
+static bool qaic_data_path_busy(struct qaic_device *qdev)
+{
+	bool ret = false;
+	int dev_rcu_id;
+	int i;
+
+	dev_rcu_id = srcu_read_lock(&qdev->dev_lock);
+	if (qdev->dev_state != QAIC_ONLINE) {
+		srcu_read_unlock(&qdev->dev_lock, dev_rcu_id);
+		return false;
+	}
+	for (i = 0; i < qdev->num_dbc; i++) {
+		struct dma_bridge_chan *dbc = &qdev->dbc[i];
+		unsigned long flags;
+		int ch_rcu_id;
+
+		ch_rcu_id = srcu_read_lock(&dbc->ch_lock);
+		if (!dbc->usr || !dbc->in_use) {
+			srcu_read_unlock(&dbc->ch_lock, ch_rcu_id);
+			continue;
+		}
+		spin_lock_irqsave(&dbc->xfer_lock, flags);
+		ret = !list_empty(&dbc->xfer_list);
+		spin_unlock_irqrestore(&dbc->xfer_lock, flags);
+		srcu_read_unlock(&dbc->ch_lock, ch_rcu_id);
+		if (ret)
+			break;
+	}
+	srcu_read_unlock(&qdev->dev_lock, dev_rcu_id);
+	return ret;
+}
+
+static int qaic_pm_suspend(struct device *dev)
+{
+	struct qaic_device *qdev = pci_get_drvdata(to_pci_dev(dev));
+
+	dev_dbg(dev, "Suspending..\n");
+	if (qaic_data_path_busy(qdev)) {
+		dev_dbg(dev, "Device's datapath is busy. Aborting suspend..\n");
+		return -EBUSY;
+	}
+	if (qaic_is_under_reset(qdev)) {
+		dev_dbg(dev, "Device is under reset. Aborting suspend..\n");
+		return -EBUSY;
+	}
+	qaic_mqts_ch_stop_timer(qdev->mqts_ch);
+	qaic_pci_reset_prepare(qdev->pdev);
+	pci_save_state(qdev->pdev);
+	pci_disable_device(qdev->pdev);
+	pci_set_power_state(qdev->pdev, PCI_D3hot);
+	return 0;
+}
+
+static int qaic_pm_resume(struct device *dev)
+{
+	struct qaic_device *qdev = pci_get_drvdata(to_pci_dev(dev));
+	int ret;
+
+	dev_dbg(dev, "Resuming..\n");
+	pci_set_power_state(qdev->pdev, PCI_D0);
+	pci_restore_state(qdev->pdev);
+	ret = pci_enable_device(qdev->pdev);
+	if (ret) {
+		dev_err(dev, "pci_enable_device failed on resume %d\n", ret);
+		return ret;
+	}
+	pci_set_master(qdev->pdev);
+	qaic_pci_reset_done(qdev->pdev);
+	return 0;
+}
+
+static const struct dev_pm_ops qaic_pm_ops = {
+	SYSTEM_SLEEP_PM_OPS(qaic_pm_suspend, qaic_pm_resume)
+};
+
 static struct pci_driver qaic_pci_driver = {
 	.name = QAIC_NAME,
 	.id_table = qaic_ids,
@@ -667,6 +753,9 @@ static struct pci_driver qaic_pci_driver = {
 	.remove = qaic_pci_remove,
 	.shutdown = qaic_pci_shutdown,
 	.err_handler = &qaic_pci_err_handler,
+	.driver = {
+		.pm = pm_sleep_ptr(&qaic_pm_ops),
+	},
 };
 
 static int __init qaic_init(void)
diff --git a/drivers/accel/qaic/qaic_timesync.c b/drivers/accel/qaic/qaic_timesync.c
index 3fac540f8e03..8af2475f4f36 100644
--- a/drivers/accel/qaic/qaic_timesync.c
+++ b/drivers/accel/qaic/qaic_timesync.c
@@ -171,6 +171,13 @@ static void qaic_timesync_timer(struct timer_list *t)
 		dev_err(mqtsdev->dev, "%s mod_timer error:%d\n", __func__, ret);
 }
 
+void qaic_mqts_ch_stop_timer(struct mhi_device *mhi_dev)
+{
+	struct mqts_dev *mqtsdev = dev_get_drvdata(&mhi_dev->dev);
+
+	timer_delete_sync(&mqtsdev->timer);
+}
+
 static int qaic_timesync_probe(struct mhi_device *mhi_dev, const struct mhi_device_id *id)
 {
 	struct qaic_device *qdev = pci_get_drvdata(to_pci_dev(mhi_dev->mhi_cntrl->cntrl_dev));
@@ -206,6 +213,7 @@ static int qaic_timesync_probe(struct mhi_device *mhi_dev, const struct mhi_devi
 	timer->expires = jiffies + msecs_to_jiffies(timesync_delay_ms);
 	add_timer(timer);
 	dev_set_drvdata(&mhi_dev->dev, mqtsdev);
+	qdev->mqts_ch = mhi_dev;
 
 	return 0;
 
@@ -221,6 +229,7 @@ static void qaic_timesync_remove(struct mhi_device *mhi_dev)
 {
 	struct mqts_dev *mqtsdev = dev_get_drvdata(&mhi_dev->dev);
 
+	mqtsdev->qdev->mqts_ch = NULL;
 	timer_delete_sync(&mqtsdev->timer);
 	mhi_unprepare_from_transfer(mqtsdev->mhi_dev);
 	kfree(mqtsdev->sync_msg);
diff --git a/drivers/accel/qaic/qaic_timesync.h b/drivers/accel/qaic/qaic_timesync.h
index 851b7acd43bb..77b9c2b55057 100644
--- a/drivers/accel/qaic/qaic_timesync.h
+++ b/drivers/accel/qaic/qaic_timesync.h
@@ -6,6 +6,9 @@
 #ifndef __QAIC_TIMESYNC_H__
 #define __QAIC_TIMESYNC_H__
 
+#include <linux/mhi.h>
+
 int qaic_timesync_init(void);
 void qaic_timesync_deinit(void);
+void qaic_mqts_ch_stop_timer(struct mhi_device *mhi_dev);
 #endif /* __QAIC_TIMESYNC_H__ */
-- 
2.34.1