ACPI / utils: Add acpi_dev_present()

There's an idiom in use by 7 Linux drivers to detect the presence of a
particular ACPI HID by walking the namespace with acpi_get_devices().
The callback passed to acpi_get_devices() is mostly identical across
the drivers, leading to lots of duplicate code.

Add acpi_dev_present(), the ACPI equivalent to pci_dev_present(),
allowing us to deduplicate all that boilerplate in the drivers.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 11d87bf67e738ce7e7a07541993b92bbb66e423a..60bda0d2cf9a82793a18c9aceef8facdb7a632d4 100644 (file)
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -86,6 +86,14 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
 #define ACPI_STA_DEFAULT (ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED | \
                          ACPI_STA_DEVICE_UI | ACPI_STA_DEVICE_FUNCTIONING)
 
+extern struct list_head acpi_bus_id_list;
+
+struct acpi_device_bus_id{
+       char bus_id[15];
+       unsigned int instance_no;
+       struct list_head node;
+};
+
 int acpi_device_add(struct acpi_device *device,
                    void (*release)(struct device *));
 void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index be1fc12a17ee605bbf7dc2c0ea4f52f31b35c309..407a3760e8de659863fb4f6cea274a78bf11ff7b 100644 (file)
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -39,7 +39,7 @@ static const char *dummy_hid = "device";
 
 static LIST_HEAD(acpi_dep_list);
 static DEFINE_MUTEX(acpi_dep_list_lock);
-static LIST_HEAD(acpi_bus_id_list);
+LIST_HEAD(acpi_bus_id_list);
 static DEFINE_MUTEX(acpi_scan_lock);
 static LIST_HEAD(acpi_scan_handlers_list);
 DEFINE_MUTEX(acpi_device_lock);
@@ -52,12 +52,6 @@ struct acpi_dep_data {
        acpi_handle slave;
 };
 
-struct acpi_device_bus_id{
-       char bus_id[15];
-       unsigned int instance_no;
-       struct list_head node;
-};
-
 void acpi_scan_lock_acquire(void)
 {
        mutex_lock(&acpi_scan_lock);

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 475c9079bf856761157887c73ad4d1ec57a98992..f2f9873bb5c363699b49459ebc2fcc9a00af0776 100644 (file)
--- 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.

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index ad0a5ff3d4cd724128b36074d428f475155df1b4..0fe7babf9c24ba62708c6538bef7093b5a6b9f0f 100644 (file)
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -87,6 +87,8 @@ acpi_evaluate_dsm_typed(acpi_handle handle, const u8 *uuid, int rev, int func,
          .package.elements = (eles)                    \
        }
 
+bool acpi_dev_present(const char *hid);
+
 #ifdef CONFIG_ACPI
 
 #include <linux/proc_fs.h>