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path: root/drivers/acpi/utils.c
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-rw-r--r--drivers/acpi/utils.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 475c9079b..f2f9873bb 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -29,6 +29,7 @@
#include <linux/dynamic_debug.h>
#include "internal.h"
+#include "sleep.h"
#define _COMPONENT ACPI_BUS_COMPONENT
ACPI_MODULE_NAME("utils");
@@ -709,6 +710,36 @@ bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
}
EXPORT_SYMBOL(acpi_check_dsm);
+/**
+ * acpi_dev_present - Detect presence of a given ACPI device in the system.
+ * @hid: Hardware ID of the device.
+ *
+ * Return %true if the device was present at the moment of invocation.
+ * Note that if the device is pluggable, it may since have disappeared.
+ *
+ * For this function to work, acpi_bus_scan() must have been executed
+ * which happens in the subsys_initcall() subsection. Hence, do not
+ * call from a subsys_initcall() or earlier (use acpi_get_devices()
+ * instead). Calling from module_init() is fine (which is synonymous
+ * with device_initcall()).
+ */
+bool acpi_dev_present(const char *hid)
+{
+ struct acpi_device_bus_id *acpi_device_bus_id;
+ bool found = false;
+
+ mutex_lock(&acpi_device_lock);
+ list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node)
+ if (!strcmp(acpi_device_bus_id->bus_id, hid)) {
+ found = true;
+ break;
+ }
+ mutex_unlock(&acpi_device_lock);
+
+ return found;
+}
+EXPORT_SYMBOL(acpi_dev_present);
+
/*
* acpi_backlight= handling, this is done here rather then in video_detect.c
* because __setup cannot be used in modules.