[PATCH v2 1/4] ACPI: EC: Add query notifier support

[Armin Wolf <W_Armin@xxxxxx>]

Allow external drivers to register notifiers to act on
query events and possibly override the query handler.
Use the existing notifier infrastructure for this to
ensure correct locking.

Tested on a Acer Travelmate 4002WLMi.

Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
---
 drivers/acpi/ec.c       | 28 ++++++++++++++++++++++++----
 drivers/acpi/internal.h |  5 +++++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 105d2e795afa..dc7860a825a0 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -18,6 +18,7 @@

 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/notifier.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/delay.h>
@@ -184,6 +185,8 @@ static int EC_FLAGS_CORRECT_ECDT; /* Needs ECDT port address correction */
 static int EC_FLAGS_TRUST_DSDT_GPE; /* Needs DSDT GPE as correction setting */
 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */

+static BLOCKING_NOTIFIER_HEAD(acpi_ec_chain_head);
+
 /* --------------------------------------------------------------------------
  *                           Logging/Debugging
  * -------------------------------------------------------------------------- */
@@ -1125,18 +1128,35 @@ void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
 }
 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);

+int register_acpi_ec_query_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&acpi_ec_chain_head, nb);
+}
+EXPORT_SYMBOL_GPL(register_acpi_ec_query_notifier);
+
+int unregister_acpi_ec_query_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&acpi_ec_chain_head, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_acpi_ec_query_notifier);
+
 static void acpi_ec_event_processor(struct work_struct *work)
 {
 	struct acpi_ec_query *q = container_of(work, struct acpi_ec_query, work);
 	struct acpi_ec_query_handler *handler = q->handler;
 	struct acpi_ec *ec = q->ec;
+	int ret;

 	ec_dbg_evt("Query(0x%02x) started", handler->query_bit);

-	if (handler->func)
-		handler->func(handler->data);
-	else if (handler->handle)
-		acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
+	/* Allow notifier handlers to override query handlers */
+	ret = blocking_notifier_call_chain(&acpi_ec_chain_head, handler->query_bit, ec);
+	if (ret != NOTIFY_BAD) {
+		if (handler->func)
+			handler->func(handler->data);
+		else if (handler->handle)
+			acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
+	}

 	ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit);

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index ec584442fb29..6f41d42375ab 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -11,6 +11,8 @@

 #include <linux/idr.h>

+struct notifier_block;
+
 int early_acpi_osi_init(void);
 int acpi_osi_init(void);
 acpi_status acpi_os_initialize1(void);
@@ -212,6 +214,9 @@ int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
 			      void *data);
 void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit);

+int register_acpi_ec_query_notifier(struct notifier_block *nb);
+int unregister_acpi_ec_query_notifier(struct notifier_block *nb);
+
 #ifdef CONFIG_PM_SLEEP
 void acpi_ec_flush_work(void);
 bool acpi_ec_dispatch_gpe(void);
--
2.30.2