nvmem: add support for cell lookups from machine code

Add a way for machine code users to associate devices with nvmem cells.

This restores the support for non-DT systems but following a different
approach. Cells must now be associated with devices using provided
routines and data structures before they can be retrieved using
nvmem_cell_get().

It's still possible to define cells statically in nvmem_config but
cells created this way still need to be associated with consumers using
lookup entries.

Note that nvmem_find() must be moved higher in the source file as we
want to call it from __nvmem_device_get() for devices that don't have
a device node.

The signature of __nvmem_device_get() is also changed as it's no longer
used to retrieve cells.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 74b6b97680d53ffb9e37e3179f1565ecdbaf8b23..9cc86d131e1e0afb5ed8764bc2aaf1facabd33e0 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -62,6 +62,9 @@ static DEFINE_IDA(nvmem_ida);
 static DEFINE_MUTEX(nvmem_cell_mutex);
 static LIST_HEAD(nvmem_cell_tables);
 
+static DEFINE_MUTEX(nvmem_lookup_mutex);
+static LIST_HEAD(nvmem_lookup_list);
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key eeprom_lock_key;
 #endif
@@ -283,6 +286,18 @@ static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
        return to_nvmem_device(d);
 }
 
+static struct nvmem_device *nvmem_find(const char *name)
+{
+       struct device *d;
+
+       d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
+
+       if (!d)
+               return NULL;
+
+       return to_nvmem_device(d);
+}
+
 static void nvmem_cell_drop(struct nvmem_cell *cell)
 {
        mutex_lock(&nvmem_mutex);
@@ -472,6 +487,21 @@ nvmem_find_cell_by_index(struct nvmem_device *nvmem, int index)
        return cell;
 }
 
+static struct nvmem_cell *
+nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
+{
+       struct nvmem_cell *cell = NULL;
+
+       mutex_lock(&nvmem_mutex);
+       list_for_each_entry(cell, &nvmem->cells, node) {
+               if (strcmp(cell_id, cell->name) == 0)
+                       break;
+       }
+       mutex_unlock(&nvmem_mutex);
+
+       return cell;
+}
+
 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 {
        struct device_node *parent, *child;
@@ -719,16 +749,12 @@ int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 EXPORT_SYMBOL(devm_nvmem_unregister);
 
 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
-                                              struct nvmem_cell **cellp,
-                                              const char *cell_id)
+                                              const char *nvmem_name)
 {
        struct nvmem_device *nvmem = NULL;
 
-       if (!np)
-               return ERR_PTR(-ENOENT);
-
        mutex_lock(&nvmem_mutex);
-       nvmem = of_nvmem_find(np);
+       nvmem = np ? of_nvmem_find(np) : nvmem_find(nvmem_name);
        mutex_unlock(&nvmem_mutex);
        if (!nvmem)
                return ERR_PTR(-EPROBE_DEFER);
@@ -752,18 +778,6 @@ static void __nvmem_device_put(struct nvmem_device *nvmem)
        kref_put(&nvmem->refcnt, nvmem_device_release);
 }
 
-static struct nvmem_device *nvmem_find(const char *name)
-{
-       struct device *d;
-
-       d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
-
-       if (!d)
-               return ERR_PTR(-ENOENT);
-
-       return to_nvmem_device(d);
-}
-
 #if IS_ENABLED(CONFIG_OF)
 /**
  * of_nvmem_device_get() - Get nvmem device from a given id
@@ -786,7 +800,7 @@ struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
        if (!nvmem_np)
                return ERR_PTR(-EINVAL);
 
-       return __nvmem_device_get(nvmem_np, NULL, NULL);
+       return __nvmem_device_get(nvmem_np, NULL);
 }
 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
 #endif
@@ -890,15 +904,43 @@ struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
 }
 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
 
-static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
+static struct nvmem_cell *
+nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
 {
-       struct nvmem_cell *cell = NULL;
+       struct nvmem_cell *cell = ERR_PTR(-ENOENT);
+       struct nvmem_cell_lookup *lookup;
        struct nvmem_device *nvmem;
+       const char *dev_id;
 
-       nvmem = __nvmem_device_get(NULL, &cell, cell_id);
-       if (IS_ERR(nvmem))
-               return ERR_CAST(nvmem);
+       if (!dev)
+               return ERR_PTR(-EINVAL);
+
+       dev_id = dev_name(dev);
+
+       mutex_lock(&nvmem_lookup_mutex);
+
+       list_for_each_entry(lookup, &nvmem_lookup_list, node) {
+               if ((strcmp(lookup->dev_id, dev_id) == 0) &&
+                   (strcmp(lookup->con_id, con_id) == 0)) {
+                       /* This is the right entry. */
+                       nvmem = __nvmem_device_get(NULL, lookup->nvmem_name);
+                       if (!nvmem) {
+                               /* Provider may not be registered yet. */
+                               cell = ERR_PTR(-EPROBE_DEFER);
+                               goto out;
+                       }
+
+                       cell = nvmem_find_cell_by_name(nvmem,
+                                                      lookup->cell_name);
+                       if (!cell) {
+                               __nvmem_device_put(nvmem);
+                               goto out;
+                       }
+               }
+       }
 
+out:
+       mutex_unlock(&nvmem_lookup_mutex);
        return cell;
 }
 
@@ -935,7 +977,7 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
        if (!nvmem_np)
                return ERR_PTR(-EINVAL);
 
-       nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
+       nvmem = __nvmem_device_get(nvmem_np, NULL);
        of_node_put(nvmem_np);
        if (IS_ERR(nvmem))
                return ERR_CAST(nvmem);
@@ -975,7 +1017,7 @@ struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
        if (!cell_id)
                return ERR_PTR(-EINVAL);
 
-       return nvmem_cell_get_from_list(cell_id);
+       return nvmem_cell_get_from_lookup(dev, cell_id);
 }
 EXPORT_SYMBOL_GPL(nvmem_cell_get);
 
@@ -1405,6 +1447,41 @@ void nvmem_del_cell_table(struct nvmem_cell_table *table)
 }
 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
 
+/**
+ * nvmem_add_cell_lookups() - register a list of cell lookup entries
+ *
+ * @entries: array of cell lookup entries
+ * @nentries: number of cell lookup entries in the array
+ */
+void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
+{
+       int i;
+
+       mutex_lock(&nvmem_lookup_mutex);
+       for (i = 0; i < nentries; i++)
+               list_add_tail(&entries[i].node, &nvmem_lookup_list);
+       mutex_unlock(&nvmem_lookup_mutex);
+}
+EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
+
+/**
+ * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
+ *                            entries
+ *
+ * @entries: array of cell lookup entries
+ * @nentries: number of cell lookup entries in the array
+ */
+void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
+{
+       int i;
+
+       mutex_lock(&nvmem_lookup_mutex);
+       for (i = 0; i < nentries; i++)
+               list_del(&entries[i].node);
+       mutex_unlock(&nvmem_lookup_mutex);
+}
+EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
+
 /**
  * nvmem_dev_name() - Get the name of a given nvmem device.
  *

diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 0389fe00b17748f2568c3dc059f4d412e3d3007d..27eee394540548bfeeb77176fad442d7ee7582ac 100644 (file)
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -29,6 +29,24 @@ struct nvmem_cell_info {
        unsigned int            nbits;
 };
 
+/**
+ * struct nvmem_cell_lookup - cell lookup entry
+ *
+ * @nvmem_name:        Name of the provider.
+ * @cell_name: Name of the nvmem cell as defined in the name field of
+ *             struct nvmem_cell_info.
+ * @dev_id:    Name of the consumer device that will be associated with
+ *             this cell.
+ * @con_id:    Connector id for this cell lookup.
+ */
+struct nvmem_cell_lookup {
+       const char              *nvmem_name;
+       const char              *cell_name;
+       const char              *dev_id;
+       const char              *con_id;
+       struct list_head        node;
+};
+
 #if IS_ENABLED(CONFIG_NVMEM)
 
 /* Cell based interface */
@@ -57,6 +75,11 @@ int nvmem_device_cell_write(struct nvmem_device *nvmem,
 
 const char *nvmem_dev_name(struct nvmem_device *nvmem);
 
+void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries,
+                           size_t nentries);
+void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries,
+                           size_t nentries);
+
 #else
 
 static inline struct nvmem_cell *nvmem_cell_get(struct device *dev,
@@ -151,6 +174,11 @@ static inline const char *nvmem_dev_name(struct nvmem_device *nvmem)
        return NULL;
 }
 
+static inline void
+nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries) {}
+static inline void
+nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries) {}
+
 #endif /* CONFIG_NVMEM */
 
 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)