diff options
| -rw-r--r-- | Documentation/devicetree/changesets.txt | 40 | ||||
| -rw-r--r-- | drivers/of/dynamic.c | 344 | ||||
| -rw-r--r-- | drivers/of/of_private.h | 9 | ||||
| -rw-r--r-- | drivers/of/selftest.c | 51 | ||||
| -rw-r--r-- | drivers/of/testcase-data/testcases.dtsi | 10 | ||||
| -rw-r--r-- | include/linux/of.h | 76 |
6 files changed, 530 insertions, 0 deletions
diff --git a/Documentation/devicetree/changesets.txt b/Documentation/devicetree/changesets.txt new file mode 100644 index 000000000000..935ba5acc34e --- /dev/null +++ b/Documentation/devicetree/changesets.txt @@ -0,0 +1,40 @@ +A DT changeset is a method which allows one to apply changes +in the live tree in such a way that either the full set of changes +will be applied, or none of them will be. If an error occurs partway +through applying the changeset, then the tree will be rolled back to the +previous state. A changeset can also be removed after it has been +applied. + +When a changeset is applied, all of the changes get applied to the tree +at once before emitting OF_RECONFIG notifiers. This is so that the +receiver sees a complete and consistent state of the tree when it +receives the notifier. + +The sequence of a changeset is as follows. + +1. of_changeset_init() - initializes a changeset + +2. A number of DT tree change calls, of_changeset_attach_node(), +of_changeset_detach_node(), of_changeset_add_property(), +of_changeset_remove_property, of_changeset_update_property() to prepare +a set of changes. No changes to the active tree are made at this point. +All the change operations are recorded in the of_changeset 'entries' +list. + +3. mutex_lock(of_mutex) - starts a changeset; The global of_mutex +ensures there can only be one editor at a time. + +4. of_changeset_apply() - Apply the changes to the tree. Either the +entire changeset will get applied, or if there is an error the tree will +be restored to the previous state + +5. mutex_unlock(of_mutex) - All operations complete, release the mutex + +If a successfully applied changeset needs to be removed, it can be done +with the following sequence. + +1. mutex_lock(of_mutex) + +2. of_changeset_revert() + +3. mutex_unlock(of_mutex) 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; +} diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index f69ccb1fa308..858e0a5d9a11 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -81,4 +81,13 @@ extern int __of_attach_node_sysfs(struct device_node *np); extern void __of_detach_node(struct device_node *np); extern void __of_detach_node_sysfs(struct device_node *np); +/* iterators for transactions, used for overlays */ +/* forward iterator */ +#define for_each_transaction_entry(_oft, _te) \ + list_for_each_entry(_te, &(_oft)->te_list, node) + +/* reverse iterator */ +#define for_each_transaction_entry_reverse(_oft, _te) \ + list_for_each_entry_reverse(_te, &(_oft)->te_list, node) + #endif /* _LINUX_OF_PRIVATE_H */ diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c index ee2166f0f36a..04e39a183e53 100644 --- a/drivers/of/selftest.c +++ b/drivers/of/selftest.c @@ -293,6 +293,56 @@ static void __init of_selftest_property_copy(void) #endif } +static void __init of_selftest_changeset(void) +{ +#ifdef CONFIG_OF_DYNAMIC + struct property *ppadd, padd = { .name = "prop-add", .length = 0, .value = "" }; + struct property *ppupdate, pupdate = { .name = "prop-update", .length = 5, .value = "abcd" }; + struct property *ppremove; + struct device_node *n1, *n2, *n21, *nremove, *parent; + struct of_changeset chgset; + + of_changeset_init(&chgset); + n1 = __of_node_alloc("/testcase-data/changeset/n1", GFP_KERNEL); + selftest(n1, "testcase setup failure\n"); + n2 = __of_node_alloc("/testcase-data/changeset/n2", GFP_KERNEL); + selftest(n2, "testcase setup failure\n"); + n21 = __of_node_alloc("/testcase-data/changeset/n2/n21", GFP_KERNEL); + selftest(n21, "testcase setup failure %p\n", n21); + nremove = of_find_node_by_path("/testcase-data/changeset/node-remove"); + selftest(nremove, "testcase setup failure\n"); + ppadd = __of_prop_dup(&padd, GFP_KERNEL); + selftest(ppadd, "testcase setup failure\n"); + ppupdate = __of_prop_dup(&pupdate, GFP_KERNEL); + selftest(ppupdate, "testcase setup failure\n"); + parent = nremove->parent; + n1->parent = parent; + n2->parent = parent; + n21->parent = n2; + n2->child = n21; + ppremove = of_find_property(parent, "prop-remove", NULL); + selftest(ppremove, "failed to find removal prop"); + + of_changeset_init(&chgset); + selftest(!of_changeset_attach_node(&chgset, n1), "fail attach n1\n"); + selftest(!of_changeset_attach_node(&chgset, n2), "fail attach n2\n"); + selftest(!of_changeset_detach_node(&chgset, nremove), "fail remove node\n"); + selftest(!of_changeset_attach_node(&chgset, n21), "fail attach n21\n"); + selftest(!of_changeset_add_property(&chgset, parent, ppadd), "fail add prop\n"); + selftest(!of_changeset_update_property(&chgset, parent, ppupdate), "fail update prop\n"); + selftest(!of_changeset_remove_property(&chgset, parent, ppremove), "fail remove prop\n"); + mutex_lock(&of_mutex); + selftest(!of_changeset_apply(&chgset), "apply failed\n"); + mutex_unlock(&of_mutex); + + mutex_lock(&of_mutex); + selftest(!of_changeset_revert(&chgset), "revert failed\n"); + mutex_unlock(&of_mutex); + + of_changeset_destroy(&chgset); +#endif +} + static void __init of_selftest_parse_interrupts(void) { struct device_node *np; @@ -561,6 +611,7 @@ static int __init of_selftest(void) of_selftest_parse_phandle_with_args(); of_selftest_property_match_string(); of_selftest_property_copy(); + of_selftest_changeset(); of_selftest_parse_interrupts(); of_selftest_parse_interrupts_extended(); of_selftest_match_node(); diff --git a/drivers/of/testcase-data/testcases.dtsi b/drivers/of/testcase-data/testcases.dtsi index 6d8d980ac858..669bb07df142 100644 --- a/drivers/of/testcase-data/testcases.dtsi +++ b/drivers/of/testcase-data/testcases.dtsi @@ -1,3 +1,13 @@ +/ { + testcase-data { + changeset { + prop-update = "hello"; + prop-remove = "world"; + node-remove { + }; + }; + }; +}; #include "tests-phandle.dtsi" #include "tests-interrupts.dtsi" #include "tests-match.dtsi" diff --git a/include/linux/of.h b/include/linux/of.h index 400f18cb4fff..bc91fbb13ce8 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -786,4 +786,80 @@ typedef void (*of_init_fn_1)(struct device_node *); #define OF_DECLARE_2(table, name, compat, fn) \ _OF_DECLARE(table, name, compat, fn, of_init_fn_2) +/** + * struct of_changeset_entry - Holds a changeset entry + * + * @node: list_head for the log list + * @action: notifier action + * @np: pointer to the device node affected + * @prop: pointer to the property affected + * @old_prop: hold a pointer to the original property + * + * Every modification of the device tree during a changeset + * is held in a list of of_changeset_entry structures. + * That way we can recover from a partial application, or we can + * revert the changeset + */ +struct of_changeset_entry { + struct list_head node; + unsigned long action; + struct device_node *np; + struct property *prop; + struct property *old_prop; +}; + +/** + * struct of_changeset - changeset tracker structure + * + * @entries: list_head for the changeset entries + * + * changesets are a convenient way to apply bulk changes to the + * live tree. In case of an error, changes are rolled-back. + * changesets live on after initial application, and if not + * destroyed after use, they can be reverted in one single call. + */ +struct of_changeset { + struct list_head entries; +}; + +#ifdef CONFIG_OF_DYNAMIC +extern void of_changeset_init(struct of_changeset *ocs); +extern void of_changeset_destroy(struct of_changeset *ocs); +extern int of_changeset_apply(struct of_changeset *ocs); +extern int of_changeset_revert(struct of_changeset *ocs); +extern int of_changeset_action(struct of_changeset *ocs, + unsigned long action, struct device_node *np, + struct property *prop); + +static inline int of_changeset_attach_node(struct of_changeset *ocs, + struct device_node *np) +{ + return of_changeset_action(ocs, OF_RECONFIG_ATTACH_NODE, np, NULL); +} + +static inline int of_changeset_detach_node(struct of_changeset *ocs, + struct device_node *np) +{ + return of_changeset_action(ocs, OF_RECONFIG_DETACH_NODE, np, NULL); +} + +static inline int of_changeset_add_property(struct of_changeset *ocs, + struct device_node *np, struct property *prop) +{ + return of_changeset_action(ocs, OF_RECONFIG_ADD_PROPERTY, np, prop); +} + +static inline int of_changeset_remove_property(struct of_changeset *ocs, + struct device_node *np, struct property *prop) +{ + return of_changeset_action(ocs, OF_RECONFIG_REMOVE_PROPERTY, np, prop); +} + +static inline int of_changeset_update_property(struct of_changeset *ocs, + struct device_node *np, struct property *prop) +{ + return of_changeset_action(ocs, OF_RECONFIG_UPDATE_PROPERTY, np, prop); +} +#endif + #endif /* _LINUX_OF_H */ |