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Subject[PATCH 1/5] of/device: Add of_ functions for device_link_{add,remove}
Date
Allows to create and remove links between consumer and suppliers from 
device-tree data. Use 'links-add' property from consumer node to setup
a link with a list of suppliers.
Consumers will be suspend before their suppliers and resume after them.

Add devm_of_device_links_add() to automatically remove the links
when the device is unbound from the bus.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
---
drivers/of/device.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of_device.h | 20 +++++++++
2 files changed, 123 insertions(+)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 3717f2a20d0d..011ba9bf7642 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -336,3 +336,106 @@ int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
return 0;
}
EXPORT_SYMBOL_GPL(of_device_uevent_modalias);
+
+/**
+ * of_device_links_add - Create links between consumer and suppliers from
+ * device tree data
+ *
+ * @consumer: consumer device
+ *
+ * Returns 0 on success, < 0 on failure.
+ */
+int of_device_links_add(struct device *consumer)
+{
+ struct device_node *np;
+ struct platform_device *pdev;
+ int i = 0;
+
+ np = of_parse_phandle(consumer->of_node, "links-add", i++);
+ while (np) {
+ pdev = of_find_device_by_node(np);
+ of_node_put(np);
+ if (!pdev)
+ return -EINVAL;
+
+ device_link_add(consumer, &pdev->dev, DL_FLAG_STATELESS);
+ platform_device_put(pdev);
+
+ np = of_parse_phandle(consumer->of_node, "links-add", i++);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_device_links_add);
+
+/**
+ * of_device_links_remove - Remove links between consumer and suppliers from
+ * device tree data
+ *
+ * @consumer: consumer device
+ *
+ * Returns 0 on success, < 0 on failure.
+ */
+int of_device_links_remove(struct device *consumer)
+{
+ struct device_node *np;
+ struct platform_device *pdev;
+ int i = 0;
+
+ np = of_parse_phandle(consumer->of_node, "links-add", i++);
+ while (np) {
+ pdev = of_find_device_by_node(np);
+ of_node_put(np);
+ if (!pdev)
+ return -EINVAL;
+
+ device_link_remove(consumer, &pdev->dev);
+ platform_device_put(pdev);
+
+ np = of_parse_phandle(consumer->of_node, "links-add", i++);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_device_links_remove);
+
+static void devm_of_device_links_remove(struct device *dev, void *res)
+{
+ of_device_links_remove(*(struct device **)res);
+}
+
+/**
+ * devm_of_device_links_add - Create links between consumer and suppliers
+ * from device tree data
+ *
+ * @consumer: consumer device
+ *
+ * Returns 0 on success, < 0 on failure.
+ *
+ * Similar to of_device_links_add(), but will automatically call
+ * of_device_links_remove() when the device is unbound from the bus.
+ */
+int devm_of_device_links_add(struct device *consumer)
+{
+ struct device **ptr;
+ int ret;
+
+ if (!consumer)
+ return -EINVAL;
+
+ ptr = devres_alloc(devm_of_device_links_remove,
+ sizeof(*ptr), GFP_KERNEL);
+ if (!ptr)
+ return -ENOMEM;
+
+ ret = of_device_links_add(consumer);
+ if (ret < 0) {
+ devres_free(ptr);
+ } else {
+ *ptr = consumer;
+ devres_add(consumer, ptr);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(devm_of_device_links_add);
diff --git a/include/linux/of_device.h b/include/linux/of_device.h
index 8d31e39dd564..ad01db6828e8 100644
--- a/include/linux/of_device.h
+++ b/include/linux/of_device.h
@@ -41,6 +41,11 @@ extern int of_device_request_module(struct device *dev);
extern void of_device_uevent(struct device *dev, struct kobj_uevent_env *env);
extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env);

+
+extern int of_device_links_add(struct device *consumer);
+extern int of_device_links_remove(struct device *consumer);
+extern int devm_of_device_links_add(struct device *consumer);
+
static inline void of_device_node_put(struct device *dev)
{
of_node_put(dev->of_node);
@@ -91,6 +96,21 @@ static inline int of_device_uevent_modalias(struct device *dev,
return -ENODEV;
}

+static int of_device_links_add(struct device *consumer)
+{
+ return 0;
+}
+
+static int of_device_links_remove(struct device *consumer)
+{
+ return 0;
+}
+
+static int devm_of_device_links_add(struct device *consumer)
+{
+ return 0;
+}
+
static inline void of_device_node_put(struct device *dev) { }

static inline const struct of_device_id *__of_match_device(
--
2.15.0
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