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>
diff --git a/drivers/nvdimm/region.c b/drivers/nvdimm/region.c
new file mode 100644
index 0000000..ade3dba8
--- /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);