ACPICA: Events: Introduce acpi_set_gpe()/acpi_finish_gpe() to reduce divergences

This can help to reduce source code differences between Linux and ACPICA
upstream. Further driver cleanups also require these APIs to eliminate GPE
storms.
1. acpi_set_gpe(): An API that driver should invoke in the case it wants
                   to disable/enable IRQ without honoring the reference
                   count implemented in the acpi_disable_gpe() and
                   acpi_enable_gpe(). Note that this API should only be
                   invoked inside a acpi_enable_gpe()/acpi_disable_gpe()
                   pair.
2. acpi_finish_gpe(): Drivers returned ACPI_REENABLE_GPE unset from the
                      GPE handler should use this API instead of
                      invoking acpi_set_gpe()/acpi_enable_gpe() to
                      re-enable the GPE.
The GPE APIs can be invoked inside of a GPE handler or in the task context
with a driver provided lock held. This driver provided lock is safe to be
held in the GPE handler by the driver.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/evxfgpe.c

@@ -183,6 +183,68 @@ acpi_status acpi_disable_gpe(acpi_handle gpe_device, u32 gpe_number)
 
 ACPI_EXPORT_SYMBOL(acpi_disable_gpe)
 
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_set_gpe
+ *
+ * PARAMETERS:  gpe_device          - Parent GPE Device. NULL for GPE0/GPE1
+ *              gpe_number          - GPE level within the GPE block
+ *              action              - ACPI_GPE_ENABLE or ACPI_GPE_DISABLE
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Enable or disable an individual GPE. This function bypasses
+ *              the reference count mechanism used in the acpi_enable_gpe and
+ *              acpi_disable_gpe interfaces -- and should be used with care.
+ *
+ * Note: Typically used to disable a runtime GPE for short period of time,
+ * then re-enable it, without disturbing the existing reference counts. This
+ * is useful, for example, in the Embedded Controller (EC) driver.
+ *
+ ******************************************************************************/
+acpi_status acpi_set_gpe(acpi_handle gpe_device, u32 gpe_number, u8 action)
+{
+	struct acpi_gpe_event_info *gpe_event_info;
+	acpi_status status;
+	acpi_cpu_flags flags;
+
+	ACPI_FUNCTION_TRACE(acpi_set_gpe);
+
+	flags = acpi_os_acquire_lock(acpi_gbl_gpe_lock);
+
+	/* Ensure that we have a valid GPE number */
+
+	gpe_event_info = acpi_ev_get_gpe_event_info(gpe_device, gpe_number);
+	if (!gpe_event_info) {
+		status = AE_BAD_PARAMETER;
+		goto unlock_and_exit;
+	}
+
+	/* Perform the action */
+
+	switch (action) {
+	case ACPI_GPE_ENABLE:
+
+		status = acpi_ev_enable_gpe(gpe_event_info);
+		break;
+
+	case ACPI_GPE_DISABLE:
+
+		status = acpi_hw_low_set_gpe(gpe_event_info, ACPI_GPE_DISABLE);
+		break;
+
+	default:
+
+		status = AE_BAD_PARAMETER;
+		break;
+	}
+
+unlock_and_exit:
+	acpi_os_release_lock(acpi_gbl_gpe_lock, flags);
+	return_ACPI_STATUS(status);
+}
+
+ACPI_EXPORT_SYMBOL(acpi_set_gpe)
 
 /*******************************************************************************
  *
@@ -530,6 +592,49 @@ acpi_get_gpe_status(acpi_handle gpe_device,
 
 ACPI_EXPORT_SYMBOL(acpi_get_gpe_status)
 
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_finish_gpe
+ *
+ * PARAMETERS:  gpe_device          - Namespace node for the GPE Block
+ *                                    (NULL for FADT defined GPEs)
+ *              gpe_number          - GPE level within the GPE block
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Clear and conditionally reenable a GPE. This completes the GPE
+ *              processing. Intended for use by asynchronous host-installed
+ *              GPE handlers. The GPE is only reenabled if the enable_for_run bit
+ *              is set in the GPE info.
+ *
+ ******************************************************************************/
+acpi_status acpi_finish_gpe(acpi_handle gpe_device, u32 gpe_number)
+{
+	struct acpi_gpe_event_info *gpe_event_info;
+	acpi_status status;
+	acpi_cpu_flags flags;
+
+	ACPI_FUNCTION_TRACE(acpi_finish_gpe);
+
+	flags = acpi_os_acquire_lock(acpi_gbl_gpe_lock);
+
+	/* Ensure that we have a valid GPE number */
+
+	gpe_event_info = acpi_ev_get_gpe_event_info(gpe_device, gpe_number);
+	if (!gpe_event_info) {
+		status = AE_BAD_PARAMETER;
+		goto unlock_and_exit;
+	}
+
+	status = acpi_ev_finish_gpe(gpe_event_info);
+
+unlock_and_exit:
+	acpi_os_release_lock(acpi_gbl_gpe_lock, flags);
+	return_ACPI_STATUS(status);
+}
+
+ACPI_EXPORT_SYMBOL(acpi_finish_gpe)
+
 /******************************************************************************
  *
  * FUNCTION:    acpi_disable_all_gpes