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path: root/drivers/acpi/scan.c
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Diffstat (limited to 'drivers/acpi/scan.c')
-rw-r--r--drivers/acpi/scan.c70
1 files changed, 54 insertions, 16 deletions
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index d670158a26c5..0476e90b2091 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -142,6 +142,53 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
}
/*
+ * acpi_companion_match() - Can we match via ACPI companion device
+ * @dev: Device in question
+ *
+ * Check if the given device has an ACPI companion and if that companion has
+ * a valid list of PNP IDs, and if the device is the first (primary) physical
+ * device associated with it.
+ *
+ * If multiple physical devices are attached to a single ACPI companion, we need
+ * to be careful. The usage scenario for this kind of relationship is that all
+ * of the physical devices in question use resources provided by the ACPI
+ * companion. A typical case is an MFD device where all the sub-devices share
+ * the parent's ACPI companion. In such cases we can only allow the primary
+ * (first) physical device to be matched with the help of the companion's PNP
+ * IDs.
+ *
+ * Additional physical devices sharing the ACPI companion can still use
+ * resources available from it but they will be matched normally using functions
+ * provided by their bus types (and analogously for their modalias).
+ */
+static bool acpi_companion_match(const struct device *dev)
+{
+ struct acpi_device *adev;
+ bool ret;
+
+ adev = ACPI_COMPANION(dev);
+ if (!adev)
+ return false;
+
+ if (list_empty(&adev->pnp.ids))
+ return false;
+
+ mutex_lock(&adev->physical_node_lock);
+ if (list_empty(&adev->physical_node_list)) {
+ ret = false;
+ } else {
+ const struct acpi_device_physical_node *node;
+
+ node = list_first_entry(&adev->physical_node_list,
+ struct acpi_device_physical_node, node);
+ ret = node->dev == dev;
+ }
+ mutex_unlock(&adev->physical_node_lock);
+
+ return ret;
+}
+
+/*
* Creates uevent modalias field for ACPI enumerated devices.
* Because the other buses does not support ACPI HIDs & CIDs.
* e.g. for a device with hid:IBM0001 and cid:ACPI0001 you get:
@@ -149,20 +196,14 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
*/
int acpi_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
{
- struct acpi_device *acpi_dev;
int len;
- acpi_dev = ACPI_COMPANION(dev);
- if (!acpi_dev)
- return -ENODEV;
-
- /* Fall back to bus specific way of modalias exporting */
- if (list_empty(&acpi_dev->pnp.ids))
+ if (!acpi_companion_match(dev))
return -ENODEV;
if (add_uevent_var(env, "MODALIAS="))
return -ENOMEM;
- len = create_modalias(acpi_dev, &env->buf[env->buflen - 1],
+ len = create_modalias(ACPI_COMPANION(dev), &env->buf[env->buflen - 1],
sizeof(env->buf) - env->buflen);
if (len <= 0)
return len;
@@ -179,18 +220,12 @@ EXPORT_SYMBOL_GPL(acpi_device_uevent_modalias);
*/
int acpi_device_modalias(struct device *dev, char *buf, int size)
{
- struct acpi_device *acpi_dev;
int len;
- acpi_dev = ACPI_COMPANION(dev);
- if (!acpi_dev)
+ if (!acpi_companion_match(dev))
return -ENODEV;
- /* Fall back to bus specific way of modalias exporting */
- if (list_empty(&acpi_dev->pnp.ids))
- return -ENODEV;
-
- len = create_modalias(acpi_dev, buf, size -1);
+ len = create_modalias(ACPI_COMPANION(dev), buf, size -1);
if (len <= 0)
return len;
buf[len++] = '\n';
@@ -853,6 +888,9 @@ const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
if (!ids || !handle || acpi_bus_get_device(handle, &adev))
return NULL;
+ if (!acpi_companion_match(dev))
+ return NULL;
+
return __acpi_match_device(adev, ids);
}
EXPORT_SYMBOL_GPL(acpi_match_device);