ACPI: scan: Extend acpi_walk_dep_device_list()

The acpi_walk_dep_device_list() function is not as generic as its
name implies, serving only to decrement the dependency count for each
dependent device of the input.

Extend it to accept a callback which can be applied to all the
dependencies in acpi_dep_list.

Replace all existing calls to the function with calls to a wrapper,
passing a callback that applies the same dependency reduction.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Maximilian Luz <luzmaximilian@gmail.com>  # for platform/surface parts
Signed-off-by: Daniel Scally <djrscally@gmail.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 53 insertions, 20 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 13565629ce0a..3f7680a007a3 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1627,7 +1627,7 @@ static int acpi_ec_add(struct acpi_device *device)
 	WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);
 
 	/* Reprobe devices depending on the EC */
-	acpi_walk_dep_device_list(ec->handle);
+	acpi_dev_clear_dependencies(device);
 
 	acpi_handle_debug(ec->handle, "enumerated.\n");
 	return 0;
diff --git a/drivers/acpi/pmic/intel_pmic_chtdc_ti.c b/drivers/acpi/pmic/intel_pmic_chtdc_ti.c
index a5101b07611a..fef7831d0d63 100644
--- a/drivers/acpi/pmic/intel_pmic_chtdc_ti.c
+++ b/drivers/acpi/pmic/intel_pmic_chtdc_ti.c
@@ -117,7 +117,7 @@ static int chtdc_ti_pmic_opregion_probe(struct platform_device *pdev)
 		return err;
 
 	/* Re-enumerate devices depending on PMIC */
-	acpi_walk_dep_device_list(ACPI_HANDLE(pdev->dev.parent));
+	acpi_dev_clear_dependencies(ACPI_COMPANION(pdev->dev.parent));
 	return 0;
 }
 
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index a2df7bcf4d07..2277add6da2f 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -47,12 +47,6 @@ static DEFINE_MUTEX(acpi_hp_context_lock);
  */
 static u64 spcr_uart_addr;
 
-struct acpi_dep_data {
-	struct list_head node;
-	acpi_handle supplier;
-	acpi_handle consumer;
-};
-
 void acpi_scan_lock_acquire(void)
 {
 	mutex_lock(&acpi_scan_lock);
@@ -2107,31 +2101,70 @@ static void acpi_bus_attach(struct acpi_device *device, bool first_pass)
 		device->handler->hotplug.notify_online(device);
 }
 
-void acpi_walk_dep_device_list(acpi_handle handle)
+static int acpi_scan_clear_dep(struct acpi_dep_data *dep, void *data)
 {
-	struct acpi_dep_data *dep, *tmp;
 	struct acpi_device *adev;
 
+	acpi_bus_get_device(dep->consumer, &adev);
+
+	if (adev) {
+		adev->dep_unmet--;
+		if (!adev->dep_unmet)
+			acpi_bus_attach(adev, true);
+	}
+
+	list_del(&dep->node);
+	kfree(dep);
+
+	return 0;
+}
+
+/**
+ * acpi_walk_dep_device_list - Apply a callback to every entry in acpi_dep_list
+ * @handle:	The ACPI handle of the supplier device
+ * @callback:	Pointer to the callback function to apply
+ * @data:	Pointer to some data to pass to the callback
+ *
+ * The return value of the callback determines this function's behaviour. If 0
+ * is returned we continue to iterate over acpi_dep_list. If a positive value
+ * is returned then the loop is broken but this function returns 0. If a
+ * negative value is returned by the callback then the loop is broken and that
+ * value is returned as the final error.
+ */
+int acpi_walk_dep_device_list(acpi_handle handle,
+			      int (*callback)(struct acpi_dep_data *, void *),
+			      void *data)
+{
+	struct acpi_dep_data *dep, *tmp;
+	int ret;
+
 	mutex_lock(&acpi_dep_list_lock);
 	list_for_each_entry_safe(dep, tmp, &acpi_dep_list, node) {
 		if (dep->supplier == handle) {
-			acpi_bus_get_device(dep->consumer, &adev);
-
-			if (adev) {
-				adev->dep_unmet--;
-				if (!adev->dep_unmet)
-					acpi_bus_attach(adev, true);
-			}
-
-			list_del(&dep->node);
-			kfree(dep);
+			ret = callback(dep, data);
+			if (ret)
+				break;
 		}
 	}
 	mutex_unlock(&acpi_dep_list_lock);
+
+	return ret > 0 ? 0 : ret;
 }
 EXPORT_SYMBOL_GPL(acpi_walk_dep_device_list);
 
 /**
+ * acpi_dev_clear_dependencies - Inform consumers that the device is now active
+ * @supplier: Pointer to the supplier &struct acpi_device
+ *
+ * Clear dependencies on the given device.
+ */
+void acpi_dev_clear_dependencies(struct acpi_device *supplier)
+{
+	acpi_walk_dep_device_list(supplier->handle, acpi_scan_clear_dep, NULL);
+}
+EXPORT_SYMBOL_GPL(acpi_dev_clear_dependencies);
+
+/**
  * acpi_bus_scan - Add ACPI device node objects in a given namespace scope.
  * @handle: Root of the namespace scope to scan.
  *