1 files changed, 382 insertions, 0 deletions

diff --git a/drivers/base/component.c b/drivers/base/component.c
new file mode 100644
index 000000000000..c53efe6c6d8e
--- /dev/null
+++ b/drivers/base/component.c
@@ -0,0 +1,382 @@
+/*
+ * Componentized device handling.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This is work in progress.  We gather up the component devices into a list,
+ * and bind them when instructed.  At the moment, we're specific to the DRM
+ * subsystem, and only handles one master device, but this doesn't have to be
+ * the case.
+ */
+#include <linux/component.h>
+#include <linux/device.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+struct master {
+        struct list_head node;
+        struct list_head components;
+        bool bound;
+
+        const struct component_master_ops *ops;
+        struct device *dev;
+};
+
+struct component {
+        struct list_head node;
+        struct list_head master_node;
+        struct master *master;
+        bool bound;
+
+        const struct component_ops *ops;
+        struct device *dev;
+};
+
+static DEFINE_MUTEX(component_mutex);
+static LIST_HEAD(component_list);
+static LIST_HEAD(masters);
+
+static struct master *__master_find(struct device *dev,
+        const struct component_master_ops *ops)
+{
+        struct master *m;
+
+        list_for_each_entry(m, &masters, node)
+                if (m->dev == dev && (!ops || m->ops == ops))
+                        return m;
+
+        return NULL;
+}
+
+/* Attach an unattached component to a master. */
+static void component_attach_master(struct master *master, struct component *c)
+{
+        c->master = master;
+
+        list_add_tail(&c->master_node, &master->components);
+}
+
+/* Detach a component from a master. */
+static void component_detach_master(struct master *master, struct component *c)
+{
+        list_del(&c->master_node);
+
+        c->master = NULL;
+}
+
+int component_master_add_child(struct master *master,
+        int (*compare)(struct device *, void *), void *compare_data)
+{
+        struct component *c;
+        int ret = -ENXIO;
+
+        list_for_each_entry(c, &component_list, node) {
+                if (c->master)
+                        continue;
+
+                if (compare(c->dev, compare_data)) {
+                        component_attach_master(master, c);
+                        ret = 0;
+                        break;
+                }
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(component_master_add_child);
+
+/* Detach all attached components from this master */
+static void master_remove_components(struct master *master)
+{
+        while (!list_empty(&master->components)) {
+                struct component *c = list_first_entry(&master->components,
+                                        struct component, master_node);
+
+                WARN_ON(c->master != master);
+
+                component_detach_master(master, c);
+        }
+}
+
+/*
+ * Try to bring up a master.  If component is NULL, we're interested in
+ * this master, otherwise it's a component which must be present to try
+ * and bring up the master.
+ *
+ * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
+ */
+static int try_to_bring_up_master(struct master *master,
+        struct component *component)
+{
+        int ret = 0;
+
+        if (!master->bound) {
+                /*
+                 * Search the list of components, looking for components that
+                 * belong to this master, and attach them to the master.
+                 */
+                if (master->ops->add_components(master->dev, master)) {
+                        /* Failed to find all components */
+                        master_remove_components(master);
+                        ret = 0;
+                        goto out;
+                }
+
+                if (component && component->master != master) {
+                        master_remove_components(master);
+                        ret = 0;
+                        goto out;
+                }
+
+                /* Found all components */
+                ret = master->ops->bind(master->dev);
+                if (ret < 0) {
+                        master_remove_components(master);
+                        goto out;
+                }
+
+                master->bound = true;
+                ret = 1;
+        }
+out:
+
+        return ret;
+}
+
+static int try_to_bring_up_masters(struct component *component)
+{
+        struct master *m;
+        int ret = 0;
+
+        list_for_each_entry(m, &masters, node) {
+                ret = try_to_bring_up_master(m, component);
+                if (ret != 0)
+                        break;
+        }
+
+        return ret;
+}
+
+static void take_down_master(struct master *master)
+{
+        if (master->bound) {
+                master->ops->unbind(master->dev);
+                master->bound = false;
+        }
+
+        master_remove_components(master);
+}
+
+int component_master_add(struct device *dev,
+        const struct component_master_ops *ops)
+{
+        struct master *master;
+        int ret;
+
+        master = kzalloc(sizeof(*master), GFP_KERNEL);
+        if (!master)
+                return -ENOMEM;
+
+        master->dev = dev;
+        master->ops = ops;
+        INIT_LIST_HEAD(&master->components);
+
+        /* Add to the list of available masters. */
+        mutex_lock(&component_mutex);
+        list_add(&master->node, &masters);
+
+        ret = try_to_bring_up_master(master, NULL);
+
+        if (ret < 0) {
+                /* Delete off the list if we weren't successful */
+                list_del(&master->node);
+                kfree(master);
+        }
+        mutex_unlock(&component_mutex);
+
+        return ret < 0 ? ret : 0;
+}
+EXPORT_SYMBOL_GPL(component_master_add);
+
+void component_master_del(struct device *dev,
+        const struct component_master_ops *ops)
+{
+        struct master *master;
+
+        mutex_lock(&component_mutex);
+        master = __master_find(dev, ops);
+        if (master) {
+                take_down_master(master);
+
+                list_del(&master->node);
+                kfree(master);
+        }
+        mutex_unlock(&component_mutex);
+}
+EXPORT_SYMBOL_GPL(component_master_del);
+
+static void component_unbind(struct component *component,
+        struct master *master, void *data)
+{
+        WARN_ON(!component->bound);
+
+        component->ops->unbind(component->dev, master->dev, data);
+        component->bound = false;
+
+        /* Release all resources claimed in the binding of this component */
+        devres_release_group(component->dev, component);
+}
+
+void component_unbind_all(struct device *master_dev, void *data)
+{
+        struct master *master;
+        struct component *c;
+
+        WARN_ON(!mutex_is_locked(&component_mutex));
+
+        master = __master_find(master_dev, NULL);
+        if (!master)
+                return;
+
+        list_for_each_entry_reverse(c, &master->components, master_node)
+                component_unbind(c, master, data);
+}
+EXPORT_SYMBOL_GPL(component_unbind_all);
+
+static int component_bind(struct component *component, struct master *master,
+        void *data)
+{
+        int ret;
+
+        /*
+         * Each component initialises inside its own devres group.
+         * This allows us to roll-back a failed component without
+         * affecting anything else.
+         */
+        if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
+                return -ENOMEM;
+
+        /*
+         * Also open a group for the device itself: this allows us
+         * to release the resources claimed against the sub-device
+         * at the appropriate moment.
+         */
+        if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
+                devres_release_group(master->dev, NULL);
+                return -ENOMEM;
+        }
+
+        dev_dbg(master->dev, "binding %s (ops %ps)\n",
+                dev_name(component->dev), component->ops);
+
+        ret = component->ops->bind(component->dev, master->dev, data);
+        if (!ret) {
+                component->bound = true;
+
+                /*
+                 * Close the component device's group so that resources
+                 * allocated in the binding are encapsulated for removal
+                 * at unbind.  Remove the group on the DRM device as we
+                 * can clean those resources up independently.
+                 */
+                devres_close_group(component->dev, NULL);
+                devres_remove_group(master->dev, NULL);
+
+                dev_info(master->dev, "bound %s (ops %ps)\n",
+                         dev_name(component->dev), component->ops);
+        } else {
+                devres_release_group(component->dev, NULL);
+                devres_release_group(master->dev, NULL);
+
+                dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
+                        dev_name(component->dev), component->ops, ret);
+        }
+
+        return ret;
+}
+
+int component_bind_all(struct device *master_dev, void *data)
+{
+        struct master *master;
+        struct component *c;
+        int ret = 0;
+
+        WARN_ON(!mutex_is_locked(&component_mutex));
+
+        master = __master_find(master_dev, NULL);
+        if (!master)
+                return -EINVAL;
+
+        list_for_each_entry(c, &master->components, master_node) {
+                ret = component_bind(c, master, data);
+                if (ret)
+                        break;
+        }
+
+        if (ret != 0) {
+                list_for_each_entry_continue_reverse(c, &master->components,
+                                                     master_node)
+                        component_unbind(c, master, data);
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(component_bind_all);
+
+int component_add(struct device *dev, const struct component_ops *ops)
+{
+        struct component *component;
+        int ret;
+
+        component = kzalloc(sizeof(*component), GFP_KERNEL);
+        if (!component)
+                return -ENOMEM;
+
+        component->ops = ops;
+        component->dev = dev;
+
+        dev_dbg(dev, "adding component (ops %ps)\n", ops);
+
+        mutex_lock(&component_mutex);
+        list_add_tail(&component->node, &component_list);
+
+        ret = try_to_bring_up_masters(component);
+        if (ret < 0) {
+                list_del(&component->node);
+
+                kfree(component);
+        }
+        mutex_unlock(&component_mutex);
+
+        return ret < 0 ? ret : 0;
+}
+EXPORT_SYMBOL_GPL(component_add);
+
+void component_del(struct device *dev, const struct component_ops *ops)
+{
+        struct component *c, *component = NULL;
+
+        mutex_lock(&component_mutex);
+        list_for_each_entry(c, &component_list, node)
+                if (c->dev == dev && c->ops == ops) {
+                        list_del(&c->node);
+                        component = c;
+                        break;
+                }
+
+        if (component && component->master)
+                take_down_master(component->master);
+
+        mutex_unlock(&component_mutex);
+
+        WARN_ON(!component);
+        kfree(component);
+}
+EXPORT_SYMBOL_GPL(component_del);
+
+MODULE_LICENSE("GPL v2");