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Subject[PATCH v4 15/22] nvmem: add support for cell lookups from machine code
Date
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

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 moves 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>
---
drivers/nvmem/core.c | 129 ++++++++++++++++++++++++++-------
include/linux/nvmem-consumer.h | 28 +++++++
2 files changed, 131 insertions(+), 26 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 13568e7ad178..9cc86d131e1e 100644
--- 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 NULL;
-
- 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 0389fe00b177..27eee3945405 100644
--- 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)
--
2.18.0
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