[PATCH 2/5] nvmem: probe nvmem-cells container via driver model

[Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>]

Instead of adding NVMEM-related code into the generic OF partition
parsing, let's instead instantiate a device and bind to it via the
driver model.

This is also what Linux is currently doing for the u-boot,env driver
when not using the layout binding. The nvmem-cells binding itself is
using a MTD notifier, but for our purposes just using the driver model
is ok.

Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
 drivers/nvmem/partition.c      | 23 +++++++++++++++++++++--
 drivers/of/partition.c         |  8 ++------
 include/linux/nvmem-provider.h |  6 ------
 3 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/drivers/nvmem/partition.c b/drivers/nvmem/partition.c
index 14907e05ba2d..d1127c1401af 100644
--- a/drivers/nvmem/partition.c
+++ b/drivers/nvmem/partition.c
@@ -18,9 +18,15 @@ static int nvmem_cdev_read(void *ctx, unsigned offset, void *buf, size_t bytes)
 	return cdev_read(ctx, buf, bytes, offset, 0);
 }
 
-struct nvmem_device *nvmem_partition_register(struct cdev *cdev)
+static int nvmem_cells_probe(struct device *dev)
 {
 	struct nvmem_config config = {};
+	struct device_node *node = dev->of_node;
+	struct cdev *cdev;
+
+	cdev = cdev_by_device_node(node);
+	if (!cdev)
+		return -EINVAL;
 
 	config.name = cdev->name;
 	config.dev = cdev->dev;
@@ -32,5 +38,18 @@ struct nvmem_device *nvmem_partition_register(struct cdev *cdev)
 	config.reg_read = nvmem_cdev_read;
 	config.reg_write = nvmem_cdev_write;
 
-	return nvmem_register(&config);
+	return PTR_ERR_OR_ZERO(nvmem_register(&config));
 }
+
+static __maybe_unused struct of_device_id nvmem_cells_dt_ids[] = {
+	{ .compatible = "nvmem-cells", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, nvmem_cells_dt_ids);
+
+static struct driver nvmem_cells_driver = {
+	.name	= "nvmem_cells",
+	.probe	= nvmem_cells_probe,
+	.of_compatible = nvmem_cells_dt_ids,
+};
+device_platform_driver(nvmem_cells_driver);
diff --git a/drivers/of/partition.c b/drivers/of/partition.c
index 70297da9d231..56933cc958f7 100644
--- a/drivers/of/partition.c
+++ b/drivers/of/partition.c
@@ -76,12 +76,6 @@ struct cdev *of_parse_partition(struct cdev *cdev, struct device_node *node)
 	new->device_node = node;
 	new->flags |= DEVFS_PARTITION_FROM_OF | DEVFS_PARTITION_FOR_FIXUP;
 
-	if (IS_ENABLED(CONFIG_NVMEM) && of_device_is_compatible(node, "nvmem-cells")) {
-		struct nvmem_device *nvmem = nvmem_partition_register(new);
-		if (IS_ERR(nvmem))
-			dev_warn(cdev->dev, "nvmem registeration failed: %pe\n", nvmem);
-	}
-
 out:
 	free(filename);
 
@@ -108,6 +102,8 @@ int of_parse_partitions(struct cdev *cdev, struct device_node *node)
 		of_parse_partition(cdev, n);
 	}
 
+	if (subnode)
+		of_platform_populate(subnode, NULL, cdev->dev);
 	return 0;
 }
 
diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 41c636b3a4e0..c1765673eb23 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -47,7 +47,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *cfg);
 struct nvmem_device *nvmem_regmap_register(struct regmap *regmap, const char *name);
 struct nvmem_device *nvmem_regmap_register_with_pp(struct regmap *regmap,
 		const char *name, nvmem_cell_post_process_t cell_post_process);
-struct nvmem_device *nvmem_partition_register(struct cdev *cdev);
 struct device *nvmem_device_get_device(struct nvmem_device *nvmem);
 
 #else
@@ -69,11 +68,6 @@ nvmem_regmap_register_with_pp(struct regmap *regmap, const char *name,
 	return ERR_PTR(-ENOSYS);
 }
 
-static inline struct nvmem_device *nvmem_partition_register(struct cdev *cdev)
-{
-	return ERR_PTR(-ENOSYS);
-}
-
 static inline struct device *nvmem_device_get_device(struct nvmem_device *nvmem)
 {
 	return ERR_PTR(-ENOSYS);
-- 
2.39.5