ACPI: Add an interface to evaluate _OST

Added acpi_evaluate_hotplug_opt(). All ACPI hotplug handlers must call
this function when evaluating _OST for hotplug operations. If the
platform does not support _OST, this function returns AE_NOT_FOUND and
has no effect on the platform.

ACPI_HOTPLUG_OST is defined when all relevant ACPI hotplug operations,
such as CPU, memory and container hotplug, are enabled. This assures
consistent behavior among the hotplug operations with regarding the
_OST support. When ACPI_HOTPLUG_OST is not defined, this function is
a no-op.

ACPI PCI hotplug is not enhanced to support _OST at this time since it
is a legacy method being replaced by PCIe native hotplug. _OST support
for ACPI PCI hotplug may be added in future if necessary.

Some platforms may require the OS to support _OST in order to support
ACPI hotplug operations. For example, if a platform has the management
console where user can request a hotplug operation from, this _OST
support would be required for the management console to show the result
of the hotplug request to user.

Added macro definitions of _OST source events and status codes.
Also renamed OSC_SB_CPUHP_OST_SUPPORT to OSC_SB_HOTPLUG_OST_SUPPORT
since this _OSC bit is not specific to CPU hotplug. This bit is
defined in Table 6-147 of ACPI 5.0 as follows.

  Bits:       3
  Field Name: Insertion / Ejection _OST Processing Support
  Definition: This bit is set if OSPM will evaluate the _OST
              object defined under a device when processing
              insertion and ejection source event codes.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index adbbc1c80a26..3e87c9c538aa 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -412,3 +412,45 @@ out:
 	return status;
 }
 EXPORT_SYMBOL(acpi_get_physical_device_location);
+
+/**
+ * acpi_evaluate_hotplug_ost: Evaluate _OST for hotplug operations
+ * @handle: ACPI device handle
+ * @source_event: source event code
+ * @status_code: status code
+ * @status_buf: optional detailed information (NULL if none)
+ *
+ * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
+ * must call this function when evaluating _OST for hotplug operations.
+ * When the platform does not support _OST, this function has no effect.
+ */
+acpi_status
+acpi_evaluate_hotplug_ost(acpi_handle handle, u32 source_event,
+		u32 status_code, struct acpi_buffer *status_buf)
+{
+#ifdef ACPI_HOTPLUG_OST
+	union acpi_object params[3] = {
+		{.type = ACPI_TYPE_INTEGER,},
+		{.type = ACPI_TYPE_INTEGER,},
+		{.type = ACPI_TYPE_BUFFER,}
+	};
+	struct acpi_object_list arg_list = {3, params};
+	acpi_status status;
+
+	params[0].integer.value = source_event;
+	params[1].integer.value = status_code;
+	if (status_buf != NULL) {
+		params[2].buffer.pointer = status_buf->pointer;
+		params[2].buffer.length = status_buf->length;
+	} else {
+		params[2].buffer.pointer = NULL;
+		params[2].buffer.length = 0;
+	}
+
+	status = acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
+	return status;
+#else
+	return AE_OK;
+#endif
+}
+EXPORT_SYMBOL(acpi_evaluate_hotplug_ost);