Refactor PPS GPIO IRQ handler to use threaded IRQ

Author: by

drivers/pps/clients/pps-gpio.c

@@ -35,33 +35,44 @@ struct pps_gpio_device_data {
 	bool capture_clear;
 	unsigned int echo_active_ms;	/* PPS echo active duration */
 	unsigned long echo_timeout;	/* timer timeout value in jiffies */
+	struct pps_event_time ts;	/* timestamp captured in hardirq */
 };
 
 /*
  * Report the PPS event
  */
 
-static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
+/*
+ * Primary hardirq handler — runs in hardirq context even on PREEMPT_RT.
+ * Only captures the timestamp; all other work is deferred to the thread.
+ */
+static irqreturn_t pps_gpio_irq_hardirq(int irq, void *data)
 {
-	const struct pps_gpio_device_data *info;
-	struct pps_event_time ts;
-	int rising_edge;
+	struct pps_gpio_device_data *info = data;
+
+	pps_get_ts(&info->ts);
 
-	/* Get the time stamp first */
-	pps_get_ts(&ts);
+	return IRQ_WAKE_THREAD;
+}
 
-	info = data;
+/*
+ * Threaded handler — processes the PPS event using the timestamp
+ * captured in hardirq context above.
+ */
+static irqreturn_t pps_gpio_irq_thread(int irq, void *data)
+{
+	struct pps_gpio_device_data *info = data;
+	int rising_edge;
 
-	/* Small trick to bypass the check on edge's direction when capture_clear is unset */
 	rising_edge = info->capture_clear ?
 		      gpiod_get_value(info->gpio_pin) : !info->assert_falling_edge;
 	if ((rising_edge && !info->assert_falling_edge) ||
 			(!rising_edge && info->assert_falling_edge))
-		pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
+		pps_event(info->pps, &info->ts, PPS_CAPTUREASSERT, data);
 	else if (info->capture_clear &&
 			((rising_edge && info->assert_falling_edge) ||
 			(!rising_edge && !info->assert_falling_edge)))
-		pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
+		pps_event(info->pps, &info->ts, PPS_CAPTURECLEAR, data);
 	else
 		dev_warn_ratelimited(&info->pps->dev, "IRQ did not trigger any PPS event\n");
 
@@ -213,8 +224,12 @@ static int pps_gpio_probe(struct platform_device *pdev)
 	}
 
 	/* register IRQ interrupt handler */
-	ret = request_irq(data->irq, pps_gpio_irq_handler,
-			  get_irqf_trigger_flags(data), data->info.name, data);
+	
+	ret = request_threaded_irq(data->irq,
+			  pps_gpio_irq_hardirq, pps_gpio_irq_thread,
+			  get_irqf_trigger_flags(data) | IRQF_ONESHOT,
+			  data->info.name, data);
+	
 	if (ret) {
 		pps_unregister_source(data->pps);
 		dev_err(dev, "failed to acquire IRQ %d\n", data->irq);