@@ -185,3 +185,18 @@ ex::
=====================
See Documentation/devicetree/bindings/nvmem/nvmem.txt
+
+8. NVMEM layouts
+================
+
+NVMEM layouts are yet another mechanism to create cells. With the device
+tree binding it is possible to specify simple cells by using an offset
+and a length. Sometimes, the cells doesn't have a static offset, but
+the content is still well defined, e.g. tag-length-values. In this case,
+the NVMEM device content has to be first parsed and the cells need to
+be added accordingly. Layouts let you read the content of the NVMEM device
+and let you add cells dynamically.
+
+Another use case for layouts is the post processing of cells. With layouts,
+it is possible to associate a custom post processing hook to a cell. It
+even possible to add this hook to cells not created by the layout itself.
@@ -21,6 +21,10 @@ config NVMEM_SYSFS
This interface is mostly used by userspace applications to
read/write directly into nvmem.
+# Layouts
+
+source "drivers/nvmem/layouts/Kconfig"
+
# Devices
config NVMEM_APPLE_EFUSES
@@ -5,6 +5,7 @@
obj-$(CONFIG_NVMEM) += nvmem_core.o
nvmem_core-y := core.o
+obj-y += layouts/
# Devices
obj-$(CONFIG_NVMEM_APPLE_EFUSES) += nvmem-apple-efuses.o
@@ -40,6 +40,7 @@ struct nvmem_device {
nvmem_reg_write_t reg_write;
nvmem_cell_post_process_t cell_post_process;
struct gpio_desc *wp_gpio;
+ struct nvmem_layout *layout;
void *priv;
};
@@ -74,6 +75,9 @@ static LIST_HEAD(nvmem_lookup_list);
static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
+static DEFINE_SPINLOCK(nvmem_layout_lock);
+static LIST_HEAD(nvmem_layouts);
+
static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
@@ -728,6 +732,101 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
return 0;
}
+int __nvmem_layout_register(struct nvmem_layout *layout, struct module *owner)
+{
+ layout->owner = owner;
+
+ spin_lock(&nvmem_layout_lock);
+ list_add(&layout->node, &nvmem_layouts);
+ spin_unlock(&nvmem_layout_lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__nvmem_layout_register);
+
+void nvmem_layout_unregister(struct nvmem_layout *layout)
+{
+ spin_lock(&nvmem_layout_lock);
+ list_del(&layout->node);
+ spin_unlock(&nvmem_layout_lock);
+}
+EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
+
+static struct nvmem_layout *nvmem_layout_get(struct nvmem_device *nvmem)
+{
+ struct device_node *layout_np, *np = nvmem->dev.of_node;
+ struct nvmem_layout *l, *layout = NULL;
+
+ layout_np = of_get_child_by_name(np, "nvmem-layout");
+ if (!layout_np)
+ return NULL;
+
+ spin_lock(&nvmem_layout_lock);
+
+ list_for_each_entry(l, &nvmem_layouts, node) {
+ if (of_match_node(l->of_match_table, layout_np)) {
+ if (try_module_get(l->owner))
+ layout = l;
+
+ break;
+ }
+ }
+
+ spin_unlock(&nvmem_layout_lock);
+ of_node_put(layout_np);
+
+ return layout;
+}
+
+static void nvmem_layout_put(struct nvmem_layout *layout)
+{
+ if (layout)
+ module_put(layout->owner);
+}
+
+static int nvmem_add_cells_from_layout(struct nvmem_device *nvmem)
+{
+ struct nvmem_layout *layout = nvmem->layout;
+ int ret;
+
+ if (layout && layout->add_cells) {
+ ret = layout->add_cells(&nvmem->dev, nvmem, layout);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+#if IS_ENABLED(CONFIG_OF)
+/**
+ * of_nvmem_layout_get_container() - Get OF node to layout container.
+ *
+ * @nvmem: nvmem device.
+ *
+ * Return: a node pointer with refcount incremented or NULL if no
+ * container exists. Use of_node_put() on it when done.
+ */
+struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
+{
+ return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
+}
+EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
+#endif
+
+const void *nvmem_layout_get_match_data(struct nvmem_device *nvmem,
+ struct nvmem_layout *layout)
+{
+ struct device_node __maybe_unused *layout_np;
+ const struct of_device_id *match;
+
+ layout_np = of_nvmem_layout_get_container(nvmem);
+ match = of_match_node(layout->of_match_table, layout_np);
+
+ return match ? match->data : NULL;
+}
+EXPORT_SYMBOL_GPL(nvmem_layout_get_match_data);
+
/**
* nvmem_register() - Register a nvmem device for given nvmem_config.
* Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
@@ -834,6 +933,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
goto err_put_device;
}
+ /*
+ * If the driver supplied a layout by config->layout, the module
+ * pointer will be NULL and nvmem_layout_put() will be a noop.
+ */
+ nvmem->layout = config->layout ?: nvmem_layout_get(nvmem);
+
if (config->cells) {
rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
if (rval)
@@ -854,12 +959,17 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
if (rval)
goto err_remove_cells;
+ rval = nvmem_add_cells_from_layout(nvmem);
+ if (rval)
+ goto err_remove_cells;
+
blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
return nvmem;
err_remove_cells:
nvmem_device_remove_all_cells(nvmem);
+ nvmem_layout_put(nvmem->layout);
if (config->compat)
nvmem_sysfs_remove_compat(nvmem, config);
err_put_device:
@@ -881,6 +991,7 @@ static void nvmem_device_release(struct kref *kref)
device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
nvmem_device_remove_all_cells(nvmem);
+ nvmem_layout_put(nvmem->layout);
device_unregister(&nvmem->dev);
}
@@ -1246,6 +1357,15 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
return ERR_PTR(-EINVAL);
}
+ /* nvmem layouts produce cells within the nvmem-layout container */
+ if (of_node_name_eq(nvmem_np, "nvmem-layout")) {
+ nvmem_np = of_get_next_parent(nvmem_np);
+ if (!nvmem_np) {
+ of_node_put(cell_np);
+ return ERR_PTR(-EINVAL);
+ }
+ }
+
nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
of_node_put(nvmem_np);
if (IS_ERR(nvmem)) {
new file mode 100644
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "Layout Types"
+
+endmenu
new file mode 100644
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for nvmem layouts.
+#
@@ -239,6 +239,7 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
const char *id);
struct nvmem_device *of_nvmem_device_get(struct device_node *np,
const char *name);
+struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem);
#else
static inline struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
const char *id)
@@ -251,6 +252,12 @@ static inline struct nvmem_device *of_nvmem_device_get(struct device_node *np,
{
return ERR_PTR(-EOPNOTSUPP);
}
+
+static inline struct device_node *
+of_nvmem_layout_get_container(struct nvmem_device *nvmem)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
#endif /* CONFIG_NVMEM && CONFIG_OF */
#endif /* ifndef _LINUX_NVMEM_CONSUMER_H */
@@ -88,6 +88,7 @@ struct nvmem_cell_info {
* @stride: Minimum read/write access stride.
* @priv: User context passed to read/write callbacks.
* @ignore_wp: Write Protect pin is managed by the provider.
+ * @layout: Fixed layout associated with this nvmem device.
*
* Note: A default "nvmem<id>" name will be assigned to the device if
* no name is specified in its configuration. In such case "<id>" is
@@ -109,6 +110,7 @@ struct nvmem_config {
bool read_only;
bool root_only;
bool ignore_wp;
+ struct nvmem_layout *layout;
struct device_node *of_node;
bool no_of_node;
nvmem_reg_read_t reg_read;
@@ -142,6 +144,33 @@ struct nvmem_cell_table {
struct list_head node;
};
+/**
+ * struct nvmem_layout - NVMEM layout definitions
+ *
+ * @name: Layout name.
+ * @of_match_table: Open firmware match table.
+ * @add_cells: Will be called if a nvmem device is found which
+ * has this layout. The function will add layout
+ * specific cells with nvmem_add_one_cell().
+ * @owner: Pointer to struct module.
+ * @node: List node.
+ *
+ * A nvmem device can hold a well defined structure which can just be
+ * evaluated during runtime. For example a TLV list, or a list of "name=val"
+ * pairs. A nvmem layout can parse the nvmem device and add appropriate
+ * cells.
+ */
+struct nvmem_layout {
+ const char *name;
+ const struct of_device_id *of_match_table;
+ int (*add_cells)(struct device *dev, struct nvmem_device *nvmem,
+ struct nvmem_layout *layout);
+
+ /* private */
+ struct module *owner;
+ struct list_head node;
+};
+
#if IS_ENABLED(CONFIG_NVMEM)
struct nvmem_device *nvmem_register(const struct nvmem_config *cfg);
@@ -156,6 +185,14 @@ void nvmem_del_cell_table(struct nvmem_cell_table *table);
int nvmem_add_one_cell(struct nvmem_device *nvmem,
const struct nvmem_cell_info *info);
+int __nvmem_layout_register(struct nvmem_layout *layout, struct module *owner);
+#define nvmem_layout_register(layout) \
+ __nvmem_layout_register(layout, THIS_MODULE)
+void nvmem_layout_unregister(struct nvmem_layout *layout);
+
+const void *nvmem_layout_get_match_data(struct nvmem_device *nvmem,
+ struct nvmem_layout *layout);
+
#else
static inline struct nvmem_device *nvmem_register(const struct nvmem_config *c)
@@ -179,5 +216,19 @@ static inline int nvmem_add_one_cell(struct nvmem_device *nvmem,
return -EOPNOTSUPP;
}
+static inline int nvmem_layout_register(struct nvmem_layout *layout)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline void nvmem_layout_unregister(struct nvmem_layout *layout) {}
+
+static inline const void *
+nvmem_layout_get_match_data(struct nvmem_device *nvmem,
+ struct nvmem_layout *layout)
+{
+ return NULL;
+}
+
#endif /* CONFIG_NVMEM */
#endif /* ifndef _LINUX_NVMEM_PROVIDER_H */