[RFC 2/3] nvmem: Add 'nvmem-blob' driver

[Andrey Smirnov]

Add 'nvmem-blob' driver, which allows to access device tree embedded
data via NVMEM subsystem API.

Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
 Documentation/devicetree/bindings/nvmem/blob.txt |  35 ++++++
 drivers/nvmem/Makefile                           |   1 +
 drivers/nvmem/blob.c                             | 132 +++++++++++++++++++++++
 3 files changed, 168 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/blob.txt
 create mode 100644 drivers/nvmem/blob.c

diff --git a/Documentation/devicetree/bindings/nvmem/blob.txt b/Documentation/devicetree/bindings/nvmem/blob.txt
new file mode 100644
index 0000000..b299576
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/blob.txt
@@ -0,0 +1,35 @@
+= Deviece Tree Embedded Blob As NVMEM Device =
+
+This binding is designed to provide a way for a developer to reference
+data, built-in into device tree blob file, as NVMEM provider and acccess
+certain portions of that data as NVMEM cells using NVMEM consumer API.
+
+Required properties:
+- compatible: should be "nvmem-blob"
+- data: specifies data contained in nvmem device
+
+= Data cells =
+Are child nodes of nvmem-composite, bindings of which as described in
+bindings/nvmem/nvmem.txt
+
+Example:
+
+	a-blob {
+		compatible = "nvmem-blob";
+		data = [aa bb cc dd ee];
+
+		cell1: cell@0 {
+			reg = <0 5>;
+		};
+	};
+
+= Data consumers =
+Are device nodes which consume nvmem data cells.
+
+Example:
+
+	a-node {
+		...
+		nvmem-cells = <&cell1>;
+		nvmem-cell-names = "some-data";
+	};
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 95dde3f..1a1adba 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_NVMEM_SUNXI_SID)	+= nvmem_sunxi_sid.o
 nvmem_sunxi_sid-y		:= sunxi_sid.o
 obj-$(CONFIG_NVMEM_VF610_OCOTP)	+= nvmem-vf610-ocotp.o
 nvmem-vf610-ocotp-y		:= vf610-ocotp.o
+obj-y += blob.o
diff --git a/drivers/nvmem/blob.c b/drivers/nvmem/blob.c
new file mode 100644
index 0000000..3f2296b
--- /dev/null
+++ b/drivers/nvmem/blob.c
@@ -0,0 +1,132 @@
+#define DEBUG 1
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct nvmem_blob {
+	const u8 *data;
+	size_t data_size;
+};
+
+static int nvmem_blob_write(void *context, const void *data,
+				size_t count)
+{
+	return -ENOTSUPP;
+}
+
+static int nvmem_blob_read(void *context,
+			   const void *reg, size_t reg_size,
+			   void *val, size_t val_size)
+{
+	struct nvmem_blob *nblob = context;
+	const unsigned int offset = *(u32 *)reg;
+	
+	memcpy(val, nblob->data + offset,
+	       min(val_size, nblob->data_size - offset));
+	return 0;
+}
+
+static const struct regmap_bus nvmem_blob_regmap_bus = {
+	.write = nvmem_blob_write,
+	.read  = nvmem_blob_read,
+};
+
+
+static int nvmem_blob_validate_dt(struct device_node *np)
+{
+	return 0;
+}
+
+static int nvmem_blob_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct regmap *map;
+	struct nvmem_device *nvmem;
+	struct nvmem_blob *nblob;
+	struct property *pp;
+	struct nvmem_config  nv_cnf = {0};
+	struct regmap_config rm_cnf = {0};
+
+	ret = nvmem_blob_validate_dt(np);
+	if (ret < 0) {
+		dev_dbg(dev, "Device tree validation failed\n");
+		return ret;
+	}
+
+	nblob = devm_kzalloc(dev, sizeof(*nblob), GFP_KERNEL);
+	if (!nblob) {
+		dev_dbg(dev, "Not enough memory to allocate a blob\n");
+		return -ENOMEM;
+	}
+
+	pp = of_find_property(np, "data", NULL);
+	BUG_ON(!pp);
+	
+	nblob->data = pp->value;
+	nblob->data_size = pp->length;
+
+	rm_cnf.reg_bits = 32;
+	rm_cnf.val_bits = 8;
+	rm_cnf.reg_stride = 1;
+	rm_cnf.name = "nvmem-blob";
+	rm_cnf.max_register = nblob->data_size - 1;
+
+	map = devm_regmap_init(dev,
+			       &nvmem_blob_regmap_bus,
+			       nblob,
+			       &rm_cnf);
+	if (IS_ERR(map)) {
+		dev_dbg(dev, "Failed to initilize regmap\n");
+		return PTR_ERR(map);
+	}
+
+	nv_cnf.name = "nvmem-blob";
+	nv_cnf.read_only = true;
+	nv_cnf.dev = dev;
+	nv_cnf.owner = THIS_MODULE;
+
+	nvmem = nvmem_register(&nv_cnf);
+	if (IS_ERR(nvmem)) {
+		dev_dbg(dev, "Filed to register nvmem device\n");
+		return PTR_ERR(nvmem);
+	}
+
+	platform_set_drvdata(pdev, nblob);
+	return 0;
+}
+
+static int nvmem_blob_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(nvmem);
+}
+
+static const struct of_device_id nvmem_blob_dt_ids[] = {
+	{ .compatible = "nvmem-blob", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, nvmem_blob_dt_ids);
+
+static struct platform_driver nvmem_blob_driver = {
+	.probe	= nvmem_blob_probe,
+	.remove	= nvmem_blob_remove,
+	.driver = {
+		.name	= "nvmem-blob",
+		.of_match_table = nvmem_blob_dt_ids,
+	},
+};
+module_platform_driver(nvmem_blob_driver);
+
+MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@xxxxxxxxx>");
+MODULE_DESCRIPTION("FIXME");
+MODULE_LICENSE("GPL v2");
-- 
2.5.0