libnvdimm: support for legacy (non-aliasing) nvdimms

The libnvdimm region driver is an intermediary driver that translates
non-volatile "region"s into "namespace" sub-devices that are surfaced by
persistent memory block-device drivers (PMEM and BLK).

ACPI 6 introduces the concept that a given nvdimm may simultaneously
offer multiple access modes to its media through direct PMEM load/store
access, or windowed BLK mode.  Existing nvdimms mostly implement a PMEM
interface, some offer a BLK-like mode, but never both as ACPI 6 defines.
If an nvdimm is single interfaced, then there is no need for dimm
metadata labels.  For these devices we can take the region boundaries
directly to create a child namespace device (nd_namespace_io).

Acked-by: Christoph Hellwig <hch@lst.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 93 insertions, 0 deletions

diff --git a/drivers/nvdimm/region.c b/drivers/nvdimm/region.c
new file mode 100644
index 000000000000..ade3dba81afd
--- /dev/null
+++ b/drivers/nvdimm/region.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/nd.h>
+#include "nd.h"
+
+static int nd_region_probe(struct device *dev)
+{
+	int err;
+	struct nd_region_namespaces *num_ns;
+	struct nd_region *nd_region = to_nd_region(dev);
+	int rc = nd_region_register_namespaces(nd_region, &err);
+
+	num_ns = devm_kzalloc(dev, sizeof(*num_ns), GFP_KERNEL);
+	if (!num_ns)
+		return -ENOMEM;
+
+	if (rc < 0)
+		return rc;
+
+	num_ns->active = rc;
+	num_ns->count = rc + err;
+	dev_set_drvdata(dev, num_ns);
+
+	if (err == 0)
+		return 0;
+
+	if (rc == err)
+		return -ENODEV;
+
+	/*
+	 * Given multiple namespaces per region, we do not want to
+	 * disable all the successfully registered peer namespaces upon
+	 * a single registration failure.  If userspace is missing a
+	 * namespace that it expects it can disable/re-enable the region
+	 * to retry discovery after correcting the failure.
+	 * <regionX>/namespaces returns the current
+	 * "<async-registered>/<total>" namespace count.
+	 */
+	dev_err(dev, "failed to register %d namespace%s, continuing...\n",
+			err, err == 1 ? "" : "s");
+	return 0;
+}
+
+static int child_unregister(struct device *dev, void *data)
+{
+	nd_device_unregister(dev, ND_SYNC);
+	return 0;
+}
+
+static int nd_region_remove(struct device *dev)
+{
+	/* flush attribute readers and disable */
+	nvdimm_bus_lock(dev);
+	dev_set_drvdata(dev, NULL);
+	nvdimm_bus_unlock(dev);
+
+	device_for_each_child(dev, NULL, child_unregister);
+	return 0;
+}
+
+static struct nd_device_driver nd_region_driver = {
+	.probe = nd_region_probe,
+	.remove = nd_region_remove,
+	.drv = {
+		.name = "nd_region",
+	},
+	.type = ND_DRIVER_REGION_BLK | ND_DRIVER_REGION_PMEM,
+};
+
+int __init nd_region_init(void)
+{
+	return nd_driver_register(&nd_region_driver);
+}
+
+void nd_region_exit(void)
+{
+	driver_unregister(&nd_region_driver.drv);
+}
+
+MODULE_ALIAS_ND_DEVICE(ND_DEVICE_REGION_PMEM);
+MODULE_ALIAS_ND_DEVICE(ND_DEVICE_REGION_BLK);