of: Transactional DT support.

Introducing DT transactional support.

A DT transaction is a method which allows one to apply changes
in the live tree, in such a way that either the full set of changes
take effect, or the state of the tree can be rolled-back to the
state it was before it was attempted. An applied transaction
can be rolled-back at any time.

Documentation is in
	Documentation/devicetree/changesets.txt

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[glikely: Removed device notifiers and reworked to be more consistent]
Signed-off-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 344 insertions, 0 deletions

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 7bd5501736a6..c1002b7be786 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -314,3 +314,347 @@ struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags)
         kfree(node);
         return NULL;
 }
+
+static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
+{
+        of_node_put(ce->np);
+        list_del(&ce->node);
+        kfree(ce);
+}
+
+#ifdef DEBUG
+static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
+{
+        switch (ce->action) {
+        case OF_RECONFIG_ADD_PROPERTY:
+                pr_debug("%p: %s %s/%s\n",
+                        ce, "ADD_PROPERTY   ", ce->np->full_name,
+                        ce->prop->name);
+                break;
+        case OF_RECONFIG_REMOVE_PROPERTY:
+                pr_debug("%p: %s %s/%s\n",
+                        ce, "REMOVE_PROPERTY", ce->np->full_name,
+                        ce->prop->name);
+                break;
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                pr_debug("%p: %s %s/%s\n",
+                        ce, "UPDATE_PROPERTY", ce->np->full_name,
+                        ce->prop->name);
+                break;
+        case OF_RECONFIG_ATTACH_NODE:
+                pr_debug("%p: %s %s\n",
+                        ce, "ATTACH_NODE    ", ce->np->full_name);
+                break;
+        case OF_RECONFIG_DETACH_NODE:
+                pr_debug("%p: %s %s\n",
+                        ce, "DETACH_NODE    ", ce->np->full_name);
+                break;
+        }
+}
+#else
+static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
+{
+        /* empty */
+}
+#endif
+
+static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
+                                          struct of_changeset_entry *rce)
+{
+        memcpy(rce, ce, sizeof(*rce));
+
+        switch (ce->action) {
+        case OF_RECONFIG_ATTACH_NODE:
+                rce->action = OF_RECONFIG_DETACH_NODE;
+                break;
+        case OF_RECONFIG_DETACH_NODE:
+                rce->action = OF_RECONFIG_ATTACH_NODE;
+                break;
+        case OF_RECONFIG_ADD_PROPERTY:
+                rce->action = OF_RECONFIG_REMOVE_PROPERTY;
+                break;
+        case OF_RECONFIG_REMOVE_PROPERTY:
+                rce->action = OF_RECONFIG_ADD_PROPERTY;
+                break;
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                rce->old_prop = ce->prop;
+                rce->prop = ce->old_prop;
+                break;
+        }
+}
+
+static void __of_changeset_entry_notify(struct of_changeset_entry *ce, bool revert)
+{
+        struct of_changeset_entry ce_inverted;
+        int ret;
+
+        if (revert) {
+                __of_changeset_entry_invert(ce, &ce_inverted);
+                ce = &ce_inverted;
+        }
+
+        switch (ce->action) {
+        case OF_RECONFIG_ATTACH_NODE:
+        case OF_RECONFIG_DETACH_NODE:
+                ret = of_reconfig_notify(ce->action, ce->np);
+                break;
+        case OF_RECONFIG_ADD_PROPERTY:
+        case OF_RECONFIG_REMOVE_PROPERTY:
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
+                break;
+        default:
+                pr_err("%s: invalid devicetree changeset action: %i\n", __func__,
+                        (int)ce->action);
+                return;
+        }
+
+        if (ret)
+                pr_err("%s: notifier error @%s\n", __func__, ce->np->full_name);
+}
+
+static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
+{
+        struct property *old_prop, **propp;
+        unsigned long flags;
+        int ret = 0;
+
+        __of_changeset_entry_dump(ce);
+
+        raw_spin_lock_irqsave(&devtree_lock, flags);
+        switch (ce->action) {
+        case OF_RECONFIG_ATTACH_NODE:
+                __of_attach_node(ce->np);
+                break;
+        case OF_RECONFIG_DETACH_NODE:
+                __of_detach_node(ce->np);
+                break;
+        case OF_RECONFIG_ADD_PROPERTY:
+                /* If the property is in deadprops then it must be removed */
+                for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
+                        if (*propp == ce->prop) {
+                                *propp = ce->prop->next;
+                                ce->prop->next = NULL;
+                                break;
+                        }
+                }
+
+                ret = __of_add_property(ce->np, ce->prop);
+                if (ret) {
+                        pr_err("%s: add_property failed @%s/%s\n",
+                                __func__, ce->np->full_name,
+                                ce->prop->name);
+                        break;
+                }
+                break;
+        case OF_RECONFIG_REMOVE_PROPERTY:
+                ret = __of_remove_property(ce->np, ce->prop);
+                if (ret) {
+                        pr_err("%s: remove_property failed @%s/%s\n",
+                                __func__, ce->np->full_name,
+                                ce->prop->name);
+                        break;
+                }
+                break;
+
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                /* If the property is in deadprops then it must be removed */
+                for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
+                        if (*propp == ce->prop) {
+                                *propp = ce->prop->next;
+                                ce->prop->next = NULL;
+                                break;
+                        }
+                }
+
+                ret = __of_update_property(ce->np, ce->prop, &old_prop);
+                if (ret) {
+                        pr_err("%s: update_property failed @%s/%s\n",
+                                __func__, ce->np->full_name,
+                                ce->prop->name);
+                        break;
+                }
+                break;
+        default:
+                ret = -EINVAL;
+        }
+        raw_spin_unlock_irqrestore(&devtree_lock, flags);
+
+        if (ret)
+                return ret;
+
+        switch (ce->action) {
+        case OF_RECONFIG_ATTACH_NODE:
+                __of_attach_node_sysfs(ce->np);
+                break;
+        case OF_RECONFIG_DETACH_NODE:
+                __of_detach_node_sysfs(ce->np);
+                break;
+        case OF_RECONFIG_ADD_PROPERTY:
+                /* ignore duplicate names */
+                __of_add_property_sysfs(ce->np, ce->prop);
+                break;
+        case OF_RECONFIG_REMOVE_PROPERTY:
+                __of_remove_property_sysfs(ce->np, ce->prop);
+                break;
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
+                break;
+        }
+
+        return 0;
+}
+
+static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
+{
+        struct of_changeset_entry ce_inverted;
+
+        __of_changeset_entry_invert(ce, &ce_inverted);
+        return __of_changeset_entry_apply(&ce_inverted);
+}
+
+/**
+ * of_changeset_init - Initialize a changeset for use
+ *
+ * @ocs:        changeset pointer
+ *
+ * Initialize a changeset structure
+ */
+void of_changeset_init(struct of_changeset *ocs)
+{
+        memset(ocs, 0, sizeof(*ocs));
+        INIT_LIST_HEAD(&ocs->entries);
+}
+
+/**
+ * of_changeset_destroy - Destroy a changeset
+ *
+ * @ocs:        changeset pointer
+ *
+ * Destroys a changeset. Note that if a changeset is applied,
+ * its changes to the tree cannot be reverted.
+ */
+void of_changeset_destroy(struct of_changeset *ocs)
+{
+        struct of_changeset_entry *ce, *cen;
+
+        list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
+                __of_changeset_entry_destroy(ce);
+}
+
+/**
+ * of_changeset_apply - Applies a changeset
+ *
+ * @ocs:        changeset pointer
+ *
+ * Applies a changeset to the live tree.
+ * Any side-effects of live tree state changes are applied here on
+ * sucess, like creation/destruction of devices and side-effects
+ * like creation of sysfs properties and directories.
+ * Returns 0 on success, a negative error value in case of an error.
+ * On error the partially applied effects are reverted.
+ */
+int of_changeset_apply(struct of_changeset *ocs)
+{
+        struct of_changeset_entry *ce;
+        int ret;
+
+        /* perform the rest of the work */
+        pr_debug("of_changeset: applying...\n");
+        list_for_each_entry(ce, &ocs->entries, node) {
+                ret = __of_changeset_entry_apply(ce);
+                if (ret) {
+                        pr_err("%s: Error applying changeset (%d)\n", __func__, ret);
+                        list_for_each_entry_continue_reverse(ce, &ocs->entries, node)
+                                __of_changeset_entry_revert(ce);
+                        return ret;
+                }
+        }
+        pr_debug("of_changeset: applied, emitting notifiers.\n");
+
+        /* drop the global lock while emitting notifiers */
+        mutex_unlock(&of_mutex);
+        list_for_each_entry(ce, &ocs->entries, node)
+                __of_changeset_entry_notify(ce, 0);
+        mutex_lock(&of_mutex);
+        pr_debug("of_changeset: notifiers sent.\n");
+
+        return 0;
+}
+
+/**
+ * of_changeset_revert - Reverts an applied changeset
+ *
+ * @ocs:        changeset pointer
+ *
+ * Reverts a changeset returning the state of the tree to what it
+ * was before the application.
+ * Any side-effects like creation/destruction of devices and
+ * removal of sysfs properties and directories are applied.
+ * Returns 0 on success, a negative error value in case of an error.
+ */
+int of_changeset_revert(struct of_changeset *ocs)
+{
+        struct of_changeset_entry *ce;
+        int ret;
+
+        pr_debug("of_changeset: reverting...\n");
+        list_for_each_entry_reverse(ce, &ocs->entries, node) {
+                ret = __of_changeset_entry_revert(ce);
+                if (ret) {
+                        pr_err("%s: Error reverting changeset (%d)\n", __func__, ret);
+                        list_for_each_entry_continue(ce, &ocs->entries, node)
+                                __of_changeset_entry_apply(ce);
+                        return ret;
+                }
+        }
+        pr_debug("of_changeset: reverted, emitting notifiers.\n");
+
+        /* drop the global lock while emitting notifiers */
+        mutex_unlock(&of_mutex);
+        list_for_each_entry_reverse(ce, &ocs->entries, node)
+                __of_changeset_entry_notify(ce, 1);
+        mutex_lock(&of_mutex);
+        pr_debug("of_changeset: notifiers sent.\n");
+
+        return 0;
+}
+
+/**
+ * of_changeset_action - Perform a changeset action
+ *
+ * @ocs:        changeset pointer
+ * @action:     action to perform
+ * @np:         Pointer to device node
+ * @prop:       Pointer to property
+ *
+ * On action being one of:
+ * + OF_RECONFIG_ATTACH_NODE
+ * + OF_RECONFIG_DETACH_NODE,
+ * + OF_RECONFIG_ADD_PROPERTY
+ * + OF_RECONFIG_REMOVE_PROPERTY,
+ * + OF_RECONFIG_UPDATE_PROPERTY
+ * Returns 0 on success, a negative error value in case of an error.
+ */
+int of_changeset_action(struct of_changeset *ocs, unsigned long action,
+                struct device_node *np, struct property *prop)
+{
+        struct of_changeset_entry *ce;
+
+        ce = kzalloc(sizeof(*ce), GFP_KERNEL);
+        if (!ce) {
+                pr_err("%s: Failed to allocate\n", __func__);
+                return -ENOMEM;
+        }
+        /* get a reference to the node */
+        ce->action = action;
+        ce->np = of_node_get(np);
+        ce->prop = prop;
+
+        if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
+                ce->old_prop = of_find_property(np, prop->name, NULL);
+
+        /* add it to the list */
+        list_add_tail(&ce->node, &ocs->entries);
+        return 0;
+}