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path: root/drivers/amba/bus.c
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Diffstat (limited to 'drivers/amba/bus.c')
-rw-r--r--drivers/amba/bus.c100
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 *