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| author |   Dan Williams <dan.j.williams@intel.com> | 2021-02-16 20:09:50 -0800 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2021-02-16 20:36:38 -0800 |
| commit | 4cdadfd5e0a70017fec735b7b6d7f2f731842dc6 (patch) | |
| tree | 2799c35a3a590847b517271742eccde395655e6f /Documentation/driver-api | |
| parent | Linux 5.11-rc6 (diff) | |
| download | linux-dev-4cdadfd5e0a70017fec735b7b6d7f2f731842dc6.tar.xz linux-dev-4cdadfd5e0a70017fec735b7b6d7f2f731842dc6.zip | |
cxl/mem: Introduce a driver for CXL-2.0-Type-3 endpoints
The CXL.mem protocol allows a device to act as a provider of "System
RAM" and/or "Persistent Memory" that is fully coherent as if the memory
was attached to the typical CPU memory controller.
With the CXL-2.0 specification a PCI endpoint can implement a "Type-3"
device interface and give the operating system control over "Host
Managed Device Memory". See section 2.3 Type 3 CXL Device.
The memory range exported by the device may optionally be described by
the platform firmware memory map, or by infrastructure like LIBNVDIMM to
provision persistent memory capacity from one, or more, CXL.mem devices.
A pre-requisite for Linux-managed memory-capacity provisioning is this
cxl_mem driver that can speak the mailbox protocol defined in section
8.2.8.4 Mailbox Registers.
For now just land the initial driver boiler-plate and Documentation/
infrastructure.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: David Rientjes <rientjes@google.com> (v1)
Cc: Jonathan Corbet <corbet@lwn.net>
Link: https://www.computeexpresslink.org/download-the-specification
Link: https://lore.kernel.org/r/20210217040958.1354670-2-ben.widawsky@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/cxl/index.rst | 12 | ||||
| -rw-r--r-- | Documentation/driver-api/cxl/memory-devices.rst | 15 | ||||
| -rw-r--r-- | Documentation/driver-api/index.rst | 1 |
3 files changed, 28 insertions, 0 deletions
diff --git a/Documentation/driver-api/cxl/index.rst b/Documentation/driver-api/cxl/index.rst new file mode 100644 index 000000000000..036e49553542 --- /dev/null +++ b/Documentation/driver-api/cxl/index.rst @@ -0,0 +1,12 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================== +Compute Express Link +==================== + +.. toctree:: + :maxdepth: 1 + + memory-devices + +.. only:: subproject and html diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst new file mode 100644 index 000000000000..71617e9002f1 --- /dev/null +++ b/Documentation/driver-api/cxl/memory-devices.rst @@ -0,0 +1,15 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. include:: <isonum.txt> + +=================================== +Compute Express Link Memory Devices +=================================== + +A Compute Express Link Memory Device is a CXL component that implements the +CXL.mem protocol. It contains some amount of volatile memory, persistent memory, +or both. It is enumerated as a PCI device for configuration and passing +messages over an MMIO mailbox. Its contribution to the System Physical +Address space is handled via HDM (Host Managed Device Memory) decoders +that optionally define a device's contribution to an interleaved address +range across multiple devices underneath a host-bridge or interleaved +across host-bridges. diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index 2456d0a97ed8..d246a18fd78f 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -35,6 +35,7 @@ available subsections can be seen below. usb/index firewire pci/index + cxl/index spi i2c ipmb |