[PATCH 2/2] regulator: irq: freeze deferred hardware access during suspend

[Jiale Yao]

The regulator IRQ helper delays status checks and recovery callbacks on
non-freezable workqueues. Those callbacks may access regulator hardware
after the backing bus has been suspended.

Use system_freezable_wq for normal-priority callbacks. Allocate a
freezable high-priority workqueue when requested so the high_prio
contract is preserved while hardware access is frozen across suspend.

Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 drivers/regulator/irq_helpers.c | 38 +++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/drivers/regulator/irq_helpers.c b/drivers/regulator/irq_helpers.c
index 5b3cfac28667..cdbd170d2b15 100644
--- a/drivers/regulator/irq_helpers.c
+++ b/drivers/regulator/irq_helpers.c
@@ -15,6 +15,7 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/workqueue.h>
 #include <linux/regulator/driver.h>
 
 #include "internal.h"
@@ -27,6 +28,7 @@ struct regulator_irq {
 	int irq;
 	int retry_cnt;
 	struct delayed_work isr_work;
+	struct workqueue_struct *wq;
 };
 
 /*
@@ -145,12 +147,7 @@ static void regulator_notifier_isr_work(struct work_struct *work)
 	return;
 
 reschedule:
-	if (!d->high_prio)
-		mod_delayed_work(system_dfl_wq, &h->isr_work,
-				 msecs_to_jiffies(tmo));
-	else
-		mod_delayed_work(system_highpri_wq, &h->isr_work,
-				 msecs_to_jiffies(tmo));
+	mod_delayed_work(h->wq, &h->isr_work, msecs_to_jiffies(tmo));
 }
 
 static irqreturn_t regulator_notifier_isr(int irq, void *data)
@@ -248,13 +245,8 @@ static irqreturn_t regulator_notifier_isr(int irq, void *data)
 	}
 
 	if (d->irq_off_ms) {
-		if (!d->high_prio)
-			schedule_delayed_work(&h->isr_work,
-					      msecs_to_jiffies(d->irq_off_ms));
-		else
-			mod_delayed_work(system_highpri_wq,
-					 &h->isr_work,
-					 msecs_to_jiffies(d->irq_off_ms));
+		mod_delayed_work(h->wq, &h->isr_work,
+				 msecs_to_jiffies(d->irq_off_ms));
 	}
 
 	return IRQ_HANDLED;
@@ -363,13 +355,25 @@ void *regulator_irq_helper(struct device *dev,
 
 	init_rdev_errors(h);
 
-	if (h->desc.irq_off_ms)
+	if (h->desc.irq_off_ms) {
+		if (h->desc.high_prio) {
+			h->wq = alloc_workqueue("regulator_irq_highpri",
+						WQ_FREEZABLE | WQ_HIGHPRI, 0);
+			if (!h->wq)
+				return ERR_PTR(-ENOMEM);
+		} else {
+			h->wq = system_freezable_wq;
+		}
+
 		INIT_DELAYED_WORK(&h->isr_work, regulator_notifier_isr_work);
+	}
 
 	ret = request_threaded_irq(h->irq, NULL, regulator_notifier_isr,
 				   IRQF_ONESHOT | irq_flags, h->desc.name, h);
 	if (ret) {
 		dev_err(dev, "Failed to request IRQ %d\n", irq);
+		if (h->desc.irq_off_ms && h->desc.high_prio)
+			destroy_workqueue(h->wq);
 
 		return ERR_PTR(ret);
 	}
@@ -393,8 +397,11 @@ void regulator_irq_helper_cancel(void **handle)
 		struct regulator_irq *h = *handle;
 
 		free_irq(h->irq, h);
-		if (h->desc.irq_off_ms)
+		if (h->desc.irq_off_ms) {
 			cancel_delayed_work_sync(&h->isr_work);
+			if (h->desc.high_prio)
+				destroy_workqueue(h->wq);
+		}
 
 		h = NULL;
 	}
@@ -441,4 +448,3 @@ int regulator_irq_map_event_simple(int irq, struct regulator_irq_data *rid,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(regulator_irq_map_event_simple);
-
-- 
2.34.1