[PATCH net-next v4 1/2] net: pse-pd: add devm_pse_poll_helper()

[Carlo Szelinsky <github@szelinsky.de>]

Extract the common event handling loop from pse_isr() into a shared
pse_handle_events() function, and add a generic poll-based alternative
to the IRQ path for PSE controllers that lack interrupt support or
have IRQ lines not wired on the board.

The new devm_pse_poll_helper() function sets up a delayed work that
periodically calls the driver's map_event callback to detect state
changes, feeding events into the existing ntf_fifo / pse_send_ntf_worker
notification pipeline. This reuses the same pse_irq_desc interface as
the IRQ path — the driver provides a map_event callback that populates
per-PI notification arrays.

The poll worker uses system_freezable_wq to avoid running during system
suspend when the underlying hardware (e.g. I2C bus) may be inaccessible.

Work cancellation on teardown is handled via devm_add_action_or_reset()
to ensure the delayed work is cancelled before poll_notifs is freed
by devres, avoiding a use-after-free when devm_pse_poll_helper() is
called after devm_pse_controller_register() (devres LIFO ordering).

The poll interval defaults to 500ms if not set by the driver, balancing
responsiveness against bus load (e.g. I2C).

Signed-off-by: Carlo Szelinsky <github@szelinsky.de>
---
 drivers/net/pse-pd/pse_core.c | 164 +++++++++++++++++++++++++++-------
 include/linux/pse-pd/pse.h    |  12 +++
 2 files changed, 146 insertions(+), 30 deletions(-)

diff --git a/drivers/net/pse-pd/pse_core.c b/drivers/net/pse-pd/pse_core.c
index 3beaaaeec9e1..f641a6fa087f 100644
--- a/drivers/net/pse-pd/pse_core.c
+++ b/drivers/net/pse-pd/pse_core.c
@@ -14,10 +14,18 @@
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 #include <linux/rtnetlink.h>
+#include <linux/workqueue.h>
 #include <net/net_trackers.h>
 
 #define PSE_PW_D_LIMIT INT_MAX
 
+/*
+ * Default poll interval for controllers without IRQ support.
+ * 500ms provides a reasonable trade-off between responsiveness
+ * (event detection, PD detection) and I2C bus utilization.
+ */
+#define PSE_DEFAULT_POLL_INTERVAL_MS 500
+
 static DEFINE_MUTEX(pse_list_mutex);
 static LIST_HEAD(pse_controller_list);
 static DEFINE_XARRAY_ALLOC(pse_pw_d_map);
@@ -1238,66 +1246,103 @@ static int pse_set_config_isr(struct pse_controller_dev *pcdev, int id,
 }
 
 /**
- * pse_isr - IRQ handler for PSE
- * @irq: irq number
- * @data: pointer to user interrupt structure
+ * pse_handle_events - Process PSE events for all PIs
+ * @pcdev: a pointer to the PSE controller device
+ * @notifs: per-PI notification array
+ * @notifs_mask: bitmask of PIs with events
  *
- * Return: irqreturn_t - status of IRQ
+ * Common event handling shared between IRQ and poll paths.
+ * Caller must hold pcdev->lock.
  */
-static irqreturn_t pse_isr(int irq, void *data)
+static void pse_handle_events(struct pse_controller_dev *pcdev,
+			      unsigned long *notifs,
+			      unsigned long notifs_mask)
 {
-	struct pse_controller_dev *pcdev;
-	unsigned long notifs_mask = 0;
-	struct pse_irq_desc *desc;
-	struct pse_irq *h = data;
-	int ret, i;
-
-	desc = &h->desc;
-	pcdev = h->pcdev;
-
-	/* Clear notifs mask */
-	memset(h->notifs, 0, pcdev->nr_lines * sizeof(*h->notifs));
-	mutex_lock(&pcdev->lock);
-	ret = desc->map_event(irq, pcdev, h->notifs, &notifs_mask);
-	if (ret || !notifs_mask) {
-		mutex_unlock(&pcdev->lock);
-		return IRQ_NONE;
-	}
+	int i;
 
 	for_each_set_bit(i, &notifs_mask, pcdev->nr_lines) {
-		unsigned long notifs, rnotifs;
+		unsigned long pi_notifs, rnotifs;
 		struct pse_ntf ntf = {};
+		int ret;
 
 		/* Do nothing PI not described */
 		if (!pcdev->pi[i].rdev)
 			continue;
 
-		notifs = h->notifs[i];
+		pi_notifs = notifs[i];
 		if (pse_pw_d_is_sw_pw_control(pcdev, pcdev->pi[i].pw_d)) {
-			ret = pse_set_config_isr(pcdev, i, notifs);
+			ret = pse_set_config_isr(pcdev, i, pi_notifs);
 			if (ret)
-				notifs |= ETHTOOL_PSE_EVENT_SW_PW_CONTROL_ERROR;
+				pi_notifs |= ETHTOOL_PSE_EVENT_SW_PW_CONTROL_ERROR;
 		}
 
-		dev_dbg(h->pcdev->dev,
-			"Sending PSE notification EVT 0x%lx\n", notifs);
+		dev_dbg(pcdev->dev,
+			"Sending PSE notification EVT 0x%lx\n", pi_notifs);
 
-		ntf.notifs = notifs;
+		ntf.notifs = pi_notifs;
 		ntf.id = i;
 		kfifo_in_spinlocked(&pcdev->ntf_fifo, &ntf, 1,
 				    &pcdev->ntf_fifo_lock);
 		schedule_work(&pcdev->ntf_work);
 
-		rnotifs = pse_to_regulator_notifs(notifs);
+		rnotifs = pse_to_regulator_notifs(pi_notifs);
 		regulator_notifier_call_chain(pcdev->pi[i].rdev, rnotifs,
 					      NULL);
 	}
+}
+
+/**
+ * pse_isr - IRQ handler for PSE
+ * @irq: irq number
+ * @data: pointer to user interrupt structure
+ *
+ * Return: irqreturn_t - status of IRQ
+ */
+static irqreturn_t pse_isr(int irq, void *data)
+{
+	struct pse_controller_dev *pcdev;
+	unsigned long notifs_mask = 0;
+	struct pse_irq *h = data;
+	int ret;
 
+	pcdev = h->pcdev;
+
+	/* Clear notifs mask */
+	memset(h->notifs, 0, pcdev->nr_lines * sizeof(*h->notifs));
+	mutex_lock(&pcdev->lock);
+	ret = h->desc.map_event(irq, pcdev, h->notifs, &notifs_mask);
+	if (ret || !notifs_mask) {
+		mutex_unlock(&pcdev->lock);
+		return IRQ_NONE;
+	}
+
+	pse_handle_events(pcdev, h->notifs, notifs_mask);
 	mutex_unlock(&pcdev->lock);
 
 	return IRQ_HANDLED;
 }
 
+static void pse_poll_worker(struct work_struct *work)
+{
+	struct pse_controller_dev *pcdev =
+		container_of(work, struct pse_controller_dev,
+			     poll_work.work);
+	unsigned long notifs_mask = 0;
+	int ret;
+
+	memset(pcdev->poll_notifs, 0,
+	       pcdev->nr_lines * sizeof(*pcdev->poll_notifs));
+	mutex_lock(&pcdev->lock);
+	ret = pcdev->poll_desc.map_event(0, pcdev, pcdev->poll_notifs,
+					 &notifs_mask);
+	if (!ret && notifs_mask)
+		pse_handle_events(pcdev, pcdev->poll_notifs, notifs_mask);
+	mutex_unlock(&pcdev->lock);
+
+	queue_delayed_work(system_freezable_wq, &pcdev->poll_work,
+			   msecs_to_jiffies(pcdev->poll_interval_ms));
+}
+
 /**
  * devm_pse_irq_helper - Register IRQ based PSE event notifier
  * @pcdev: a pointer to the PSE
@@ -1351,6 +1396,65 @@ int devm_pse_irq_helper(struct pse_controller_dev *pcdev, int irq,
 }
 EXPORT_SYMBOL_GPL(devm_pse_irq_helper);
 
+static void pse_poll_cancel(void *data)
+{
+	struct pse_controller_dev *pcdev = data;
+
+	cancel_delayed_work_sync(&pcdev->poll_work);
+}
+
+/**
+ * devm_pse_poll_helper - Register poll-based PSE event notifier
+ * @pcdev: a pointer to the PSE controller device
+ * @d: PSE event description (uses same pse_irq_desc as IRQ path)
+ *
+ * For PSE controllers without IRQ support or with IRQ not wired. Sets
+ * up a delayed work that periodically calls the driver's map_event
+ * callback to detect state changes, feeding events into the standard
+ * notification pipeline.
+ *
+ * The poll worker uses system_freezable_wq to ensure it does not run
+ * during system suspend while the hardware may be inaccessible.
+ *
+ * Return: 0 on success and errno on failure
+ */
+int devm_pse_poll_helper(struct pse_controller_dev *pcdev,
+			 const struct pse_irq_desc *d)
+{
+	struct device *dev = pcdev->dev;
+	int ret;
+
+	if (!d || !d->map_event || !d->name)
+		return -EINVAL;
+
+	pcdev->poll_desc = *d;
+	pcdev->poll_notifs = devm_kcalloc(dev, pcdev->nr_lines,
+					  sizeof(*pcdev->poll_notifs),
+					  GFP_KERNEL);
+	if (!pcdev->poll_notifs)
+		return -ENOMEM;
+
+	if (!pcdev->poll_interval_ms)
+		pcdev->poll_interval_ms = PSE_DEFAULT_POLL_INTERVAL_MS;
+
+	INIT_DELAYED_WORK(&pcdev->poll_work, pse_poll_worker);
+	pcdev->polling = true;
+
+	/* Register devm action to cancel poll work before poll_notifs is
+	 * freed by devres. This ensures correct teardown ordering since
+	 * devm_pse_poll_helper() is called after devm_pse_controller_register().
+	 */
+	ret = devm_add_action_or_reset(dev, pse_poll_cancel, pcdev);
+	if (ret)
+		return ret;
+
+	queue_delayed_work(system_freezable_wq, &pcdev->poll_work,
+			   msecs_to_jiffies(pcdev->poll_interval_ms));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_pse_poll_helper);
+
 /* PSE control section */
 
 static void __pse_control_release(struct kref *kref)
diff --git a/include/linux/pse-pd/pse.h b/include/linux/pse-pd/pse.h
index 4e5696cfade7..44d5d10e239d 100644
--- a/include/linux/pse-pd/pse.h
+++ b/include/linux/pse-pd/pse.h
@@ -292,6 +292,11 @@ struct pse_ntf {
  * @pi: table of PSE PIs described in this controller device
  * @no_of_pse_pi: flag set if the pse_pis devicetree node is not used
  * @irq: PSE interrupt
+ * @polling: flag indicating poll-based event detection is active
+ * @poll_interval_ms: poll interval in milliseconds
+ * @poll_work: delayed work for poll-based event detection
+ * @poll_desc: copy of the driver's event descriptor for polling
+ * @poll_notifs: per-PI notification scratch space for poll worker
  * @pis_prio_max: Maximum value allowed for the PSE PIs priority
  * @supp_budget_eval_strategies: budget evaluation strategies supported
  *				 by the PSE
@@ -312,6 +317,11 @@ struct pse_controller_dev {
 	struct pse_pi *pi;
 	bool no_of_pse_pi;
 	int irq;
+	bool polling;
+	unsigned int poll_interval_ms;
+	struct delayed_work poll_work;
+	struct pse_irq_desc poll_desc;
+	unsigned long *poll_notifs;
 	unsigned int pis_prio_max;
 	u32 supp_budget_eval_strategies;
 	struct work_struct ntf_work;
@@ -345,6 +355,8 @@ int devm_pse_controller_register(struct device *dev,
 				 struct pse_controller_dev *pcdev);
 int devm_pse_irq_helper(struct pse_controller_dev *pcdev, int irq,
 			int irq_flags, const struct pse_irq_desc *d);
+int devm_pse_poll_helper(struct pse_controller_dev *pcdev,
+			 const struct pse_irq_desc *d);
 
 struct pse_control *of_pse_control_get(struct device_node *node,
 				       struct phy_device *phydev);
-- 
2.43.0