diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.rst | 1 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | drivers/of/property.c | 241 |
3 files changed, 248 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index d05d531b4ec9..6d421694d98e 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -127,6 +127,7 @@ parameter is applicable:: NET Appropriate network support is enabled. NUMA NUMA support is enabled. NFS Appropriate NFS support is enabled. + OF Devicetree is enabled. OSS OSS sound support is enabled. PV_OPS A paravirtualized kernel is enabled. PARIDE The ParIDE (parallel port IDE) subsystem is enabled. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index c7ac2f3ac99f..02df1a24f0c7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3194,6 +3194,12 @@ This can be set from sysctl after boot. See Documentation/admin-guide/sysctl/vm.rst for details. + of_devlink [OF, KNL] Create device links between consumer and + supplier devices by scanning the devictree to infer the + consumer/supplier relationships. A consumer device + will not be probed until all the supplier devices have + probed successfully. + ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. See Documentation/debugging-via-ohci1394.txt for more info. diff --git a/drivers/of/property.c b/drivers/of/property.c index d7fa75e31f22..23b5ee5b0570 100644 --- a/drivers/of/property.c +++ b/drivers/of/property.c @@ -25,6 +25,7 @@ #include <linux/of_device.h> #include <linux/of_graph.h> #include <linux/string.h> +#include <linux/moduleparam.h> #include "of_private.h" @@ -985,6 +986,245 @@ of_fwnode_device_get_match_data(const struct fwnode_handle *fwnode, return of_device_get_match_data(dev); } +static bool of_is_ancestor_of(struct device_node *test_ancestor, + struct device_node *child) +{ + of_node_get(child); + while (child) { + if (child == test_ancestor) { + of_node_put(child); + return false; + } + child = of_get_next_parent(child); + } + return true; +} + +/** + * of_link_to_phandle - Add device link to supplier from supplier phandle + * @dev: consumer device + * @sup_np: phandle to supplier device tree node + * + * Given a phandle to a supplier device tree node (@sup_np), this function + * finds the device that owns the supplier device tree node and creates a + * device link from @dev consumer device to the supplier device. This function + * doesn't create device links for invalid scenarios such as trying to create a + * link with a parent device as the consumer of its child device. In such + * cases, it returns an error. + * + * Returns: + * - 0 if link successfully created to supplier + * - -EAGAIN if linking to the supplier should be reattempted + * - -EINVAL if the supplier link is invalid and should not be created + * - -ENODEV if there is no device that corresponds to the supplier phandle + */ +static int of_link_to_phandle(struct device *dev, struct device_node *sup_np) +{ + struct device *sup_dev; + u32 dl_flags = DL_FLAG_AUTOPROBE_CONSUMER; + int ret = 0; + struct device_node *tmp_np = sup_np; + + of_node_get(sup_np); + /* + * Find the device node that contains the supplier phandle. It may be + * @sup_np or it may be an ancestor of @sup_np. + */ + while (sup_np && !of_find_property(sup_np, "compatible", NULL)) + sup_np = of_get_next_parent(sup_np); + if (!sup_np) { + dev_dbg(dev, "Not linking to %pOFP - No device\n", tmp_np); + return -ENODEV; + } + + /* + * Don't allow linking a device node as a consumer of one of its + * descendant nodes. By definition, a child node can't be a functional + * dependency for the parent node. + */ + if (!of_is_ancestor_of(dev->of_node, sup_np)) { + dev_dbg(dev, "Not linking to %pOFP - is descendant\n", sup_np); + of_node_put(sup_np); + return -EINVAL; + } + sup_dev = get_dev_from_fwnode(&sup_np->fwnode); + of_node_put(sup_np); + if (!sup_dev) + return -EAGAIN; + if (!device_link_add(dev, sup_dev, dl_flags)) + ret = -EAGAIN; + put_device(sup_dev); + return ret; +} + +/** + * parse_prop_cells - Property parsing function for suppliers + * + * @np: Pointer to device tree node containing a list + * @prop_name: Name of property to be parsed. Expected to hold phandle values + * @index: For properties holding a list of phandles, this is the index + * into the list. + * @list_name: Property name that is known to contain list of phandle(s) to + * supplier(s) + * @cells_name: property name that specifies phandles' arguments count + * + * This is a helper function to parse properties that have a known fixed name + * and are a list of phandles and phandle arguments. + * + * Returns: + * - phandle node pointer with refcount incremented. Caller must of_node_put() + * on it when done. + * - NULL if no phandle found at index + */ +static struct device_node *parse_prop_cells(struct device_node *np, + const char *prop_name, int index, + const char *list_name, + const char *cells_name) +{ + struct of_phandle_args sup_args; + + if (strcmp(prop_name, list_name)) + return NULL; + + if (of_parse_phandle_with_args(np, list_name, cells_name, index, + &sup_args)) + return NULL; + + return sup_args.np; +} + +static struct device_node *parse_clocks(struct device_node *np, + const char *prop_name, int index) +{ + return parse_prop_cells(np, prop_name, index, "clocks", "#clock-cells"); +} + +static struct device_node *parse_interconnects(struct device_node *np, + const char *prop_name, int index) +{ + return parse_prop_cells(np, prop_name, index, "interconnects", + "#interconnect-cells"); +} + +static int strcmp_suffix(const char *str, const char *suffix) +{ + unsigned int len, suffix_len; + + len = strlen(str); + suffix_len = strlen(suffix); + if (len <= suffix_len) + return -1; + return strcmp(str + len - suffix_len, suffix); +} + +static struct device_node *parse_regulators(struct device_node *np, + const char *prop_name, int index) +{ + if (index || strcmp_suffix(prop_name, "-supply")) + return NULL; + + return of_parse_phandle(np, prop_name, 0); +} + +/** + * struct supplier_bindings - Property parsing functions for suppliers + * + * @parse_prop: function name + * parse_prop() finds the node corresponding to a supplier phandle + * @parse_prop.np: Pointer to device node holding supplier phandle property + * @parse_prop.prop_name: Name of property holding a phandle value + * @parse_prop.index: For properties holding a list of phandles, this is the + * index into the list + * + * Returns: + * parse_prop() return values are + * - phandle node pointer with refcount incremented. Caller must of_node_put() + * on it when done. + * - NULL if no phandle found at index + */ +struct supplier_bindings { + struct device_node *(*parse_prop)(struct device_node *np, + const char *prop_name, int index); +}; + +static const struct supplier_bindings bindings[] = { + { .parse_prop = parse_clocks, }, + { .parse_prop = parse_interconnects, }, + { .parse_prop = parse_regulators, }, + {}, +}; + +/** + * of_link_property - Create device links to suppliers listed in a property + * @dev: Consumer device + * @con_np: The consumer device tree node which contains the property + * @prop_name: Name of property to be parsed + * + * This function checks if the property @prop_name that is present in the + * @con_np device tree node is one of the known common device tree bindings + * that list phandles to suppliers. If @prop_name isn't one, this function + * doesn't do anything. + * + * If @prop_name is one, this function attempts to create device links from the + * consumer device @dev to all the devices of the suppliers listed in + * @prop_name. + * + * Any failed attempt to create a device link will NOT result in an immediate + * return. of_link_property() must create links to all the available supplier + * devices even when attempts to create a link to one or more suppliers fail. + */ +static int of_link_property(struct device *dev, struct device_node *con_np, + const char *prop_name) +{ + struct device_node *phandle; + const struct supplier_bindings *s = bindings; + unsigned int i = 0; + bool matched = false; + int ret = 0; + + /* Do not stop at first failed link, link all available suppliers. */ + while (!matched && s->parse_prop) { + while ((phandle = s->parse_prop(con_np, prop_name, i))) { + matched = true; + i++; + if (of_link_to_phandle(dev, phandle) == -EAGAIN) + ret = -EAGAIN; + of_node_put(phandle); + } + s++; + } + return ret; +} + +static int __of_link_to_suppliers(struct device *dev, + struct device_node *con_np) +{ + struct device_node *child; + struct property *p; + int ret = 0; + + for_each_property_of_node(con_np, p) + if (of_link_property(dev, con_np, p->name)) + ret = -EAGAIN; + + return ret; +} + +static bool of_devlink; +core_param(of_devlink, of_devlink, bool, 0); + +static int of_fwnode_add_links(const struct fwnode_handle *fwnode, + struct device *dev) +{ + if (!of_devlink) + return 0; + + if (unlikely(!is_of_node(fwnode))) + return 0; + + return __of_link_to_suppliers(dev, to_of_node(fwnode)); +} + const struct fwnode_operations of_fwnode_ops = { .get = of_fwnode_get, .put = of_fwnode_put, @@ -1001,5 +1241,6 @@ const struct fwnode_operations of_fwnode_ops = { .graph_get_remote_endpoint = of_fwnode_graph_get_remote_endpoint, .graph_get_port_parent = of_fwnode_graph_get_port_parent, .graph_parse_endpoint = of_fwnode_graph_parse_endpoint, + .add_links = of_fwnode_add_links, }; EXPORT_SYMBOL_GPL(of_fwnode_ops); |