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authorHans de Goede <hdegoede@redhat.com>2017-04-19 15:02:08 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-04-19 23:53:34 +0300
commit8661423eea1a1b58417014716e3f1ba286072379 (patch)
tree686462c9b7444bbc6ae2eb338901deb356c2c98b /drivers/acpi/utils.c
parent4f7d029b9bf009fbee76bb10c0c4351a1870d2f3 (diff)
downloadlinux-8661423eea1a1b58417014716e3f1ba286072379.tar.xz
ACPI / utils: Add new acpi_dev_present helper
acpi_dev_found just iterates over all ACPI-ids and sees if one matches. This means that it will return true for devices which are in the DSDT but disabled (their _STA method returns 0). For some drivers it is useful to be able to check if a certain HID is not only present in the namespace, but also actually present as in acpi_device_is_present() will return true for the device. For example because if a certain device is present then the driver will want to use an extcon or IIO ADC channel provided by that device. This commit adds a new acpi_dev_present helper which drivers can use to this end. Like acpi_dev_found, acpi_dev_present take a HID as argument, but it also has 2 extra optional arguments to only check for an ACPI device with a specific UID and/or HRV value. This makes it more generic and allows it to replace custom code doing similar checks in several places. Arguably acpi_dev_present is what acpi_dev_found should have been, but there are too many users to just change acpi_dev_found without the risk of breaking something. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/utils.c')
-rw-r--r--drivers/acpi/utils.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 22c09952e177..27d0dcfcf47d 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -736,6 +736,72 @@ bool acpi_dev_found(const char *hid)
}
EXPORT_SYMBOL(acpi_dev_found);
+struct acpi_dev_present_info {
+ struct acpi_device_id hid[2];
+ const char *uid;
+ s64 hrv;
+};
+
+static int acpi_dev_present_cb(struct device *dev, void *data)
+{
+ struct acpi_device *adev = to_acpi_device(dev);
+ struct acpi_dev_present_info *match = data;
+ unsigned long long hrv;
+ acpi_status status;
+
+ if (acpi_match_device_ids(adev, match->hid))
+ return 0;
+
+ if (match->uid && (!adev->pnp.unique_id ||
+ strcmp(adev->pnp.unique_id, match->uid)))
+ return 0;
+
+ if (match->hrv == -1)
+ return 1;
+
+ status = acpi_evaluate_integer(adev->handle, "_HRV", NULL, &hrv);
+ if (ACPI_FAILURE(status))
+ return 0;
+
+ return hrv == match->hrv;
+}
+
+/**
+ * acpi_dev_present - Detect that a given ACPI device is present
+ * @hid: Hardware ID of the device.
+ * @uid: Unique ID of the device, pass NULL to not check _UID
+ * @hrv: Hardware Revision of the device, pass -1 to not check _HRV
+ *
+ * Return %true if a matching device was present at the moment of invocation.
+ * Note that if the device is pluggable, it may since have disappeared.
+ *
+ * Note that unlike acpi_dev_found() this function checks the status
+ * of the device. So for devices which are present in the dsdt, but
+ * which are disabled (their _STA callback returns 0) this function
+ * will return false.
+ *
+ * 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, const char *uid, s64 hrv)
+{
+ struct acpi_dev_present_info match = {};
+ struct device *dev;
+
+ strlcpy(match.hid[0].id, hid, sizeof(match.hid[0].id));
+ match.uid = uid;
+ match.hrv = hrv;
+
+ dev = bus_find_device(&acpi_bus_type, NULL, &match,
+ acpi_dev_present_cb);
+
+ return !!dev;
+}
+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.