platform/chrome: cros_ec: handle MKBP more events flag

The ChromeOS EC has support for signaling to the host that a single IRQ
can serve multiple MKBP (Matrix KeyBoard Protocol) events.

Doing this serves an optimization purpose, as it minimizes the number of
round-trips into the interrupt handling machinery, and it proves
beneficial to sensor timestamping as it keeps the desired synchronization
of event times between the two processors.

This patch adds kernel support for this EC feature, allowing the ec_irq
to loop until all events have been served.

Signed-off-by: Enrico Granata <egranata@chromium.org>
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

1 files changed, 29 insertions, 5 deletions

diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
index d3dfa27171e6..6d6ce86a1408 100644
--- a/drivers/platform/chrome/cros_ec.c
+++ b/drivers/platform/chrome/cros_ec.c
@@ -40,13 +40,23 @@ static irqreturn_t ec_irq_handler(int irq, void *data)
 	return IRQ_WAKE_THREAD;
 }
 
-static irqreturn_t ec_irq_thread(int irq, void *data)
+/**
+ * cros_ec_handle_event() - process and forward pending events on EC
+ * @ec_dev: Device with events to process.
+ *
+ * Call this function in a loop when the kernel is notified that the EC has
+ * pending events.
+ *
+ * Return: true if more events are still pending and this function should be
+ * called again.
+ */
+bool cros_ec_handle_event(struct cros_ec_device *ec_dev)
 {
-	struct cros_ec_device *ec_dev = data;
-	bool wake_event = true;
+	bool wake_event;
+	bool ec_has_more_events;
 	int ret;
 
-	ret = cros_ec_get_next_event(ec_dev, &wake_event);
+	ret = cros_ec_get_next_event(ec_dev, &wake_event, &ec_has_more_events);
 
 	/*
 	 * Signal only if wake host events or any interrupt if
@@ -59,6 +69,20 @@ static irqreturn_t ec_irq_thread(int irq, void *data)
 	if (ret > 0)
 		blocking_notifier_call_chain(&ec_dev->event_notifier,
 					     0, ec_dev);
+
+	return ec_has_more_events;
+}
+EXPORT_SYMBOL(cros_ec_handle_event);
+
+static irqreturn_t ec_irq_thread(int irq, void *data)
+{
+	struct cros_ec_device *ec_dev = data;
+	bool ec_has_more_events;
+
+	do {
+		ec_has_more_events = cros_ec_handle_event(ec_dev);
+	} while (ec_has_more_events);
+
 	return IRQ_HANDLED;
 }
 
@@ -274,7 +298,7 @@ EXPORT_SYMBOL(cros_ec_suspend);
 static void cros_ec_report_events_during_suspend(struct cros_ec_device *ec_dev)
 {
 	while (ec_dev->mkbp_event_supported &&
-	       cros_ec_get_next_event(ec_dev, NULL) > 0)
+	       cros_ec_get_next_event(ec_dev, NULL, NULL) > 0)
 		blocking_notifier_call_chain(&ec_dev->event_notifier,
 					     1, ec_dev);
 }