jesd204: collect all devices on framework init

The overall mode of operation for the framework will be that upon
initialization, the framework will collect all data (from device-trees)
for all JESD204 devices, and build internal representations for all of
them, and their respective links/topologies.

That way, when the kernel probes these devices, the JESD204 framework can
update states for these devices, links &topologies and can catch various
errors/omissions that drivers may have.
This makes it easier to see which device in a topology (of JESD204
devices) has updated/initialized and which error-ed.

Signed-off-by: Alexandru Ardelean <[email protected]>

Author: commodo

drivers/jesd204/jesd204-core.c

@@ -9,14 +9,120 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include "jesd204-priv.h"
+
+static DEFINE_MUTEX(jesd204_device_list_lock);
+static LIST_HEAD(jesd204_device_list);
+
+static unsigned int jesd204_device_count;
+
+static struct jesd204_dev *jesd204_dev_alloc(struct device_node *np)
+{
+	struct jesd204_dev *jdev;
+
+	jdev = kzalloc(sizeof(*jdev), GFP_KERNEL);
+	if (!jdev)
+		return ERR_PTR(-ENOMEM);
+
+	kref_get(&jdev->ref);
+
+	jdev->np = of_node_get(np);
+	kref_init(&jdev->ref);
+
+	list_add(&jdev->list, &jesd204_device_list);
+	jesd204_device_count++;
+
+	return jdev;
+}
+
+static int jesd204_of_create_devices(void)
+{
+	struct jesd204_dev *jdev;
+	struct device_node *np;
+	int ret;
+
+	mutex_lock(&jesd204_device_list_lock);
+
+	ret = 0;
+	for_each_node_with_property(np, "jesd204-device") {
+		jdev = jesd204_dev_alloc(np);
+		if (IS_ERR(jdev)) {
+			ret = PTR_ERR(jdev);
+			goto unlock;
+		}
+	}
+
+unlock:
+	mutex_unlock(&jesd204_device_list_lock);
+
+	return ret;
+}
+
+static void jesd204_of_unregister_devices(void)
+{
+	struct jesd204_dev *jdev, *j;
+
+	list_for_each_entry_safe(jdev, j, &jesd204_device_list, list) {
+		jesd204_dev_unregister(jdev);
+	}
+}
+
+/* Free memory allocated. */
+static void __jesd204_dev_release(struct kref *ref)
+{
+	struct jesd204_dev *jdev = container_of(ref, struct jesd204_dev, ref);
+
+	mutex_lock(&jesd204_device_list_lock);
+
+	list_del(&jdev->list);
+	of_node_put(jdev->np);
+
+	kfree(jdev);
+
+	jesd204_device_count--;
+
+	mutex_unlock(&jesd204_device_list_lock);
+}
+
+/**
+ * jesd204_dev_unregister() - unregister a device from the JESD204 subsystem
+ * @jdev:		Device structure representing the device.
+ **/
+void jesd204_dev_unregister(struct jesd204_dev *jdev)
+{
+	if (IS_ERR_OR_NULL(jdev))
+		return;
+
+	kref_put(&jdev->ref, __jesd204_dev_release);
+}
+EXPORT_SYMBOL(jesd204_dev_unregister);
 
 static int __init jesd204_init(void)
 {
+	int ret;
+
+	mutex_init(&jesd204_device_list_lock);
+
+	ret = jesd204_of_create_devices();
+	if (ret < 0)
+		goto error_unreg_devices;
+
 	return 0;
+
+error_unreg_devices:
+	jesd204_of_unregister_devices();
+	pr_err("framework error: %d\n", ret);
+	return ret;
 }
 
 static void __exit jesd204_exit(void)
 {
+	jesd204_of_unregister_devices();
+	mutex_destroy(&jesd204_device_list_lock);
 }
 
 subsys_initcall(jesd204_init);

drivers/jesd204/jesd204-priv.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/**
+ * The JESD204 framework
+ *
+ * Copyright (c) 2019 Analog Devices Inc.
+ */
+
+#ifndef _JESD204_PRIV_H_
+#define _JESD204_PRIV_H_
+
+#include <linux/jesd204/jesd204.h>
+
+struct jesd204_dev;
+
+/**
+ * struct jesd204_dev - JESD204 device
+ * @list		list entry for the framework to keep a list of devices
+ * @np			reference in the device-tree for this JESD204 device
+ * @ref			ref count for this JESD204 device
+ */
+struct jesd204_dev {
+	struct list_head		list;
+
+	struct device_node		*np;
+	struct kref			ref;
+};
+
+#endif /* _JESD204_PRIV_H_ */

include/linux/jesd204/jesd204.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/**
+ * The JESD204 framework
+ *
+ * Copyright (c) 2019 Analog Devices Inc.
+ */
+#ifndef _JESD204_H_
+#define _JESD204_H_
+
+struct jesd204_dev;
+
+#if IS_ENABLED(CONFIG_JESD204)
+
+void jesd204_dev_unregister(struct jesd204_dev *jdev);
+
+#else /* !IS_ENABLED(CONFIG_JESD204) */
+
+static inline void jesd204_dev_unregister(struct jesd204_dev *jdev) {}
+
+#endif /* IS_ENABLED(CONFIG_JESD204) */
+
+#endif