1 files changed, 90 insertions, 10 deletions

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index f0099360039e..a5b5c87e2114 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -336,16 +336,7 @@ static void amba_device_release(struct device *dev)
 	kfree(d);
 }
 
-/**
- *	amba_device_add - add a previously allocated AMBA device structure
- *	@dev: AMBA device allocated by amba_device_alloc
- *	@parent: resource parent for this devices resources
- *
- *	Claim the resource, and read the device cell ID if not already
- *	initialized.  Register the AMBA device with the Linux device
- *	manager.
- */
-int amba_device_add(struct amba_device *dev, struct resource *parent)
+static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
 {
 	u32 size;
 	void __iomem *tmp;
@@ -373,6 +364,12 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
 		goto err_release;
 	}
 
+	ret = dev_pm_domain_attach(&dev->dev, true);
+	if (ret == -EPROBE_DEFER) {
+		iounmap(tmp);
+		goto err_release;
+	}
+
 	ret = amba_get_enable_pclk(dev);
 	if (ret == 0) {
 		u32 pid, cid;
@@ -398,6 +395,7 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
 	}
 
 	iounmap(tmp);
+	dev_pm_domain_detach(&dev->dev, true);
 
 	if (ret)
 		goto err_release;
@@ -421,6 +419,88 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
  err_out:
 	return ret;
 }
+
+/*
+ * Registration of AMBA device require reading its pid and cid registers.
+ * To do this, the device must be turned on (if it is a part of power domain)
+ * and have clocks enabled. However in some cases those resources might not be
+ * yet available. Returning EPROBE_DEFER is not a solution in such case,
+ * because callers don't handle this special error code. Instead such devices
+ * are added to the special list and their registration is retried from
+ * periodic worker, until all resources are available and registration succeeds.
+ */
+struct deferred_device {
+	struct amba_device *dev;
+	struct resource *parent;
+	struct list_head node;
+};
+
+static LIST_HEAD(deferred_devices);
+static DEFINE_MUTEX(deferred_devices_lock);
+
+static void amba_deferred_retry_func(struct work_struct *dummy);
+static DECLARE_DELAYED_WORK(deferred_retry_work, amba_deferred_retry_func);
+
+#define DEFERRED_DEVICE_TIMEOUT (msecs_to_jiffies(5 * 1000))
+
+static void amba_deferred_retry_func(struct work_struct *dummy)
+{
+	struct deferred_device *ddev, *tmp;
+
+	mutex_lock(&deferred_devices_lock);
+
+	list_for_each_entry_safe(ddev, tmp, &deferred_devices, node) {
+		int ret = amba_device_try_add(ddev->dev, ddev->parent);
+
+		if (ret == -EPROBE_DEFER)
+			continue;
+
+		list_del_init(&ddev->node);
+		kfree(ddev);
+	}
+
+	if (!list_empty(&deferred_devices))
+		schedule_delayed_work(&deferred_retry_work,
+				      DEFERRED_DEVICE_TIMEOUT);
+
+	mutex_unlock(&deferred_devices_lock);
+}
+
+/**
+ *	amba_device_add - add a previously allocated AMBA device structure
+ *	@dev: AMBA device allocated by amba_device_alloc
+ *	@parent: resource parent for this devices resources
+ *
+ *	Claim the resource, and read the device cell ID if not already
+ *	initialized.  Register the AMBA device with the Linux device
+ *	manager.
+ */
+int amba_device_add(struct amba_device *dev, struct resource *parent)
+{
+	int ret = amba_device_try_add(dev, parent);
+
+	if (ret == -EPROBE_DEFER) {
+		struct deferred_device *ddev;
+
+		ddev = kmalloc(sizeof(*ddev), GFP_KERNEL);
+		if (!ddev)
+			return -ENOMEM;
+
+		ddev->dev = dev;
+		ddev->parent = parent;
+		ret = 0;
+
+		mutex_lock(&deferred_devices_lock);
+
+		if (list_empty(&deferred_devices))
+			schedule_delayed_work(&deferred_retry_work,
+					      DEFERRED_DEVICE_TIMEOUT);
+		list_add_tail(&ddev->node, &deferred_devices);
+
+		mutex_unlock(&deferred_devices_lock);
+	}
+	return ret;
+}
 EXPORT_SYMBOL_GPL(amba_device_add);
 
 static struct amba_device *