Device DAX is the device-centric analogue of Filesystem DAX
(CONFIG_FS_DAX).  It allows memory ranges to be allocated and mapped
without need of an intervening file system.  Device DAX is strict,
precise and predictable.  Specifically this interface:

1/ Guarantees fault granularity with respect to a given page size (pte,
pmd, or pud) set at configuration time.

2/ Enforces deterministic behavior by being strict about what fault
scenarios are supported.

For example, by forcing MADV_DONTFORK semantics and omitting MAP_PRIVATE
support device-dax guarantees that a mapping always behaves/performs the
same once established.  It is the "what you see is what you get" access
mechanism to differentiated memory vs filesystem DAX which has
filesystem specific implementation semantics.

Persistent memory is the first target, but the mechanism is also
targeted for exclusive allocations of performance differentiated memory
ranges.

This commit is limited to the base device driver infrastructure to
associate a dax device with pmem range.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Device DAX is the device-centric analogue of Filesystem DAX
(CONFIG_FS_DAX).  It allows persistent memory ranges to be allocated and
mapped without need of an intervening file system.  This initial
infrastructure arranges for a libnvdimm pfn-device to be represented as
a different device-type so that it can be attached to a driver other
than the pmem driver.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Enable nfit_test to use nd_cmd_pkg marshaling.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Clarify the distinction between "commands", the ioctls userspace calls
to request the kernel take some action on a given dimm device, and
"_DSMs", the actual function numbers used in the firmware interface to
the DIMM.  _DSMs are ACPI specific whereas commands are Linux kernel
generic.

This is in preparation for breaking the 1:1 implicit relationship
between the kernel ioctl number space and the firmware specific function
numbers.

Cc: Jerry Hoemann <jerry.hoemann@hpe.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

In preparation for providing an alternative (to block device) access
mechanism to persistent memory, convert pmem_rw_bytes() to
nsio_rw_bytes().  This allows ->rw_bytes() functionality without
requiring a 'struct pmem_device' to be instantiated.

In other words, when ->rw_bytes() is in use i/o is driven through
'struct nd_namespace_io', otherwise it is driven through 'struct
pmem_device' and the block layer.  This consolidates the disjoint calls
to devm_exit_badblocks() and devm_memunmap() into a common
devm_nsio_disable() and cleans up the init path to use a unified
pmem_attach_disk() implementation.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Provide simulated SMART data to enable the ndctl implementation of SMART
data retrieval and parsing.

The payload is defined here, "Section 4.1 SMART and Health Info
(Function Index 1)":

    http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add the boiler-plate for a 'clear error' command based on section
9.20.7.6 "Function Index 4 - Clear Uncorrectable Error" from the ACPI
6.1 specification, and add a reference implementation in nfit_test.

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>