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cxl/mem: Introduce a driver for CXL-2.0-Type-3 endpoints

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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>
This commit is contained in:
Dan Williams
2021-02-16 20:09:50 -08:00
parent 1048ba83fb
commit 4cdadfd5e0
10 changed files with 149 additions and 0 deletions
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17
drivers/cxl/pci.h Normal file
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/* SPDX-License-Identifier: GPL-2.0-only */
/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
#ifndef __CXL_PCI_H__
#define __CXL_PCI_H__
#define CXL_MEMORY_PROGIF 0x10
/*
* See section 8.1 Configuration Space Registers in the CXL 2.0
* Specification
*/
#define PCI_DVSEC_VENDOR_ID_CXL 0x1E98
#define PCI_DVSEC_ID_CXL 0x0
#define PCI_DVSEC_ID_CXL_REGLOC_OFFSET 0x8
#endif /* __CXL_PCI_H__ */