[PATCH 3/6] libnvdimm: Add device-tree based driver

[Oliver O'Halloran]

This patch adds peliminary device-tree bindings for the NVDIMM driver.
Currently this only supports one bus (created at probe time) which all
regions are added to with individual regions being created by a platform
device driver.

Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
---
I suspect the platform driver should be holding a reference to the
created region. I left that out here since previously Dan has said
he'd rather keep the struct device internal to libnvdimm and the only
other way a region device can disappear is when the bus is unregistered.
---
 MAINTAINERS                |   8 +++
 drivers/nvdimm/Kconfig     |  10 ++++
 drivers/nvdimm/Makefile    |   1 +
 drivers/nvdimm/of_nvdimm.c | 130 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 149 insertions(+)
 create mode 100644 drivers/nvdimm/of_nvdimm.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4e62756936fa..e3fc47fbfc7a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8035,6 +8035,14 @@ Q:	https://patchwork.kernel.org/project/linux-nvdimm/list/
 S:	Supported
 F:	drivers/nvdimm/pmem*
 
+LIBNVDIMM: DEVICETREE BINDINGS
+M:	Oliver O'Halloran <oohall at gmail.com>
+L:	linux-nvdimm at lists.01.org
+Q:	https://patchwork.kernel.org/project/linux-nvdimm/list/
+S:	Supported
+F:	drivers/nvdimm/of_nvdimm.c
+F:	Documentation/devicetree/bindings/nvdimm/nvdimm-bus.txt
+
 LIBNVDIMM: NON-VOLATILE MEMORY DEVICE SUBSYSTEM
 M:	Dan Williams <dan.j.williams at intel.com>
 L:	linux-nvdimm at lists.01.org
diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index a65f2e1d9f53..505a9bbbe49f 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -102,4 +102,14 @@ config NVDIMM_DAX
 
 	  Select Y if unsure
 
+config OF_NVDIMM
+	tristate "Device-tree support for NVDIMMs"
+	depends on OF
+	default LIBNVDIMM
+	help
+	  Allows byte addressable persistent memory regions to be described in the
+	  device-tree.
+
+	  Select Y if unsure.
+
 endif
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 70d5f3ad9909..fd6a5838aa25 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_BLK_DEV_PMEM) += nd_pmem.o
 obj-$(CONFIG_ND_BTT) += nd_btt.o
 obj-$(CONFIG_ND_BLK) += nd_blk.o
 obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o
+obj-$(CONFIG_OF_NVDIMM) += of_nvdimm.o
 
 nd_pmem-y := pmem.o
 
diff --git a/drivers/nvdimm/of_nvdimm.c b/drivers/nvdimm/of_nvdimm.c
new file mode 100644
index 000000000000..79c28291f420
--- /dev/null
+++ b/drivers/nvdimm/of_nvdimm.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#define pr_fmt(fmt) "of_nvdimm: " fmt
+
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/libnvdimm.h>
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+
+/*
+ * Container bus stuff.  For now we just chunk regions into a default
+ * bus with no ndctl support. In the future we'll add some mechanism
+ * for dispatching regions into the correct bus type, but this is useful
+ * for now.
+ */
+struct nvdimm_bus_descriptor bus_desc;
+struct nvdimm_bus *bus;
+
+/* region driver */
+
+static const struct attribute_group *region_attr_groups[] = {
+	&nd_region_attribute_group,
+	&nd_device_attribute_group,
+	NULL,
+};
+
+static const struct attribute_group *bus_attr_groups[] = {
+	&nvdimm_bus_attribute_group,
+	NULL,
+};
+
+static int of_nd_region_probe(struct platform_device *pdev)
+{
+	struct nd_region_desc ndr_desc;
+	struct resource temp_res;
+	struct nd_region *region;
+	struct device_node *np;
+
+	np = dev_of_node(&pdev->dev);
+	if (!np)
+		return -ENXIO;
+
+	pr_err("registering region for %pOF\n", np);
+
+	if (of_address_to_resource(np, 0, &temp_res)) {
+		pr_warn("Unable to parse reg[0] for %pOF\n", np);
+		return -ENXIO;
+	}
+
+	memset(&ndr_desc, 0, sizeof(ndr_desc));
+	ndr_desc.res = &temp_res;
+	ndr_desc.of_node = np;
+	ndr_desc.attr_groups = region_attr_groups;
+	ndr_desc.numa_node = of_node_to_nid(np);
+	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
+
+	/*
+	 * NB: libnvdimm copies the data from ndr_desc into it's own structures
+	 * so passing stack pointers is fine.
+	 */
+	if (of_get_property(np, "volatile", NULL))
+		region = nvdimm_volatile_region_create(bus, &ndr_desc);
+	else
+		region = nvdimm_pmem_region_create(bus, &ndr_desc);
+
+	pr_warn("registered pmem region %px\n", region);
+	if (!region)
+		return -ENXIO;
+
+	platform_set_drvdata(pdev, region);
+
+	return 0;
+}
+
+static int of_nd_region_remove(struct platform_device *pdev)
+{
+	struct nd_region *r = platform_get_drvdata(pdev);
+
+	nd_region_destroy(r);
+
+	return 0;
+}
+
+static const struct of_device_id of_nd_region_match[] = {
+	{ .compatible = "nvdimm-region" },
+	{ },
+};
+
+static struct platform_driver of_nd_region_driver = {
+	.probe = of_nd_region_probe,
+	.remove = of_nd_region_remove,
+	.driver = {
+		.name = "of_nd_region",
+		.owner = THIS_MODULE,
+		.of_match_table = of_nd_region_match,
+	},
+};
+
+/* bus wrangling */
+
+static int __init of_nvdimm_init(void)
+{
+	/* register  */
+	bus_desc.attr_groups = bus_attr_groups;
+	bus_desc.provider_name = "of_nvdimm";
+	bus_desc.module = THIS_MODULE;
+
+	/* does parent == NULL work? */
+	bus = nvdimm_bus_register(NULL, &bus_desc);
+	if (!bus)
+		return -ENODEV;
+
+	platform_driver_register(&of_nd_region_driver);
+
+	return 0;
+}
+module_init(of_nvdimm_init);
+
+static void __init of_nvdimm_exit(void)
+{
+	nvdimm_bus_unregister(bus);
+	platform_driver_unregister(&of_nd_region_driver);
+}
+module_exit(of_nvdimm_exit);
+
+MODULE_DEVICE_TABLE(of, of_nd_region_match);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("IBM Corporation");
-- 
2.9.5