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A cxl_decoder is a child of a cxl_port. It represents a hardware decoder
configuration of an upstream port to one or more of its downstream
ports. The decoder is either represented in CXL standard HDM decoder
registers (see CXL 2.0 section 8.2.5.12 CXL HDM Decoder Capability
Structure), or it is a static decode configuration communicated by
platform firmware (see the CXL Early Discovery Table: Fixed Memory
Window Structure).
The firmware described and hardware described decoders differ slightly
leading to 2 different sub-types of decoders, cxl_decoder_root and
cxl_decoder_switch. At the root level the decode capabilities restrict
what can be mapped beneath them. Mid-level switch decoders are
configured for either acclerator (type-2) or memory-expander (type-3)
operation, but they are otherwise agnostic to the type of memory
(volatile vs persistent) being mapped.
Here is an example topology from a single-ported host-bridge environment
without CFMWS decodes enumerated.
/sys/bus/cxl/devices/root0
├── devtype
├── dport0 -> ../../../LNXSYSTM:00/LNXSYBUS:00/ACPI0016:00
├── port1
│ ├── decoder1.0
│ │ ├── devtype
│ │ ├── locked
│ │ ├── size
│ │ ├── start
│ │ ├── subsystem -> ../../../../../../bus/cxl
│ │ ├── target_list
│ │ ├── target_type
│ │ └── uevent
│ ├── devtype
│ ├── dport0 -> ../../../../pci0000:34/0000:34:00.0
│ ├── subsystem -> ../../../../../bus/cxl
│ ├── uevent
│ └── uport -> ../../../../LNXSYSTM:00/LNXSYBUS:00/ACPI0016:00
├── subsystem -> ../../../../bus/cxl
├── uevent
└── uport -> ../../ACPI0017:00
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325695128.2293823.17519927266014762694.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for infrastructure that enumerates and configures the CXL
decode mechanism of an upstream port to its downstream ports, add a
representation of a CXL downstream port.
On ACPI systems the top-most logical downstream ports in the hierarchy
are the host bridges (ACPI0016 devices) that decode the memory windows
described by the CXL Early Discovery Table Fixed Memory Window
Structures (CEDT.CFMWS).
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/162325450624.2293126.3533006409920271718.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
While CXL builds upon the PCI software model for enumeration and
endpoint control, a static platform component is required to bootstrap
the CXL memory layout. Similar to how ACPI identifies root-level PCI
memory resources, ACPI data enumerates the address space and interleave
configuration for CXL Memory.
In addition to identifying host bridges, ACPI is responsible for
enumerating the CXL memory space that can be addressed by downstream
decoders. This is similar to the requirement for ACPI to publish
resources via the _CRS method for PCI host bridges. Specifically, ACPI
publishes a table, CXL Early Discovery Table (CEDT), which includes a
list of CXL Memory resources, CXL Fixed Memory Window Structures
(CFMWS).
For now, introduce the core infrastructure for a cxl_port hierarchy
starting with a root level anchor represented by the ACPI0017 device.
Follow on changes model support for the configurable decode capabilities
of cxl_port instances, i.e. CXL switch support.
Co-developed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325449515.2293126.15303270193010154608.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
An HDM decoder is defined in the CXL 2.0 specification as a mechanism
that allow devices and upstream ports to claim memory address ranges and
participate in interleave sets. HDM decoder registers are within the
component register block defined in CXL 2.0 8.2.3 CXL 2.0 Component
Registers as part of the CXL.cache and CXL.mem subregion.
The Component Register Block is found via the Register Locator DVSEC
in a similar fashion to how the CXL Device Register Block is found. The
primary difference is the capability id size of the Component Register
Block is a single DWORD instead of 4 DWORDS.
It's now possible to configure a CXL type 3 device's HDM decoder. Such
programming is expected for CXL devices with persistent memory, and hot
plugged CXL devices that participate in CXL.mem with volatile memory.
Add probe and mapping functions for the component register blocks.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Co-developed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Co-developed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/20210528004922.3980613-6-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The information required to map registers based on capabilities is
contained within the bars themselves. This means the bar must be mapped
to read the information needed and then unmapped to map the individual
parts of the BAR based on capabilities.
Change cxl_setup_device_regs() to return a new cxl_register_map, change
the name to cxl_probe_device_regs(). Allocate and place
cxl_register_maps on a list while processing all of the specified
register blocks.
After probing all the register blocks go back and map smaller registers
blocks based on their capabilities and dispose of the cxl_register_maps.
NOTE: pci_iomap() is not managed automatically via pcim_enable_device()
so be careful to call pci_iounmap() correctly.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20210604005036.4187184-1-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
While CXL Memory Device endpoints locate the CXL MMIO registers in a PCI
BAR, CXL root bridges have their MMIO base address described by platform
firmware. Refactor the existing register lookup into a generic facility
for endpoints and bridges to share.
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162096972534.1865304.3218686216153688039.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
CXL MMIO register blocks are organized by device type and capabilities.
There are Component registers, Device registers (yes, an ambiguous
name), and Memory Device registers (a specific extension of Device
registers).
It is possible for a given device instance (endpoint or port) to
implement register sets from multiple of the above categories.
The driver code that enumerates and maps the registers is type specific
so it is useful to have a dedicated type and helpers for each block
type.
At the same time, once the registers are mapped the origin type does not
matter. It is overly pedantic to reference the register block type in
code that is using the registers.
In preparation for the endpoint driver to incorporate Component registers
into its MMIO operations reorganize the registers to allow typed
enumeration + mapping, but anonymous usage. With the end state of
'struct cxl_regs' to be:
struct cxl_regs {
union {
struct {
CXL_DEVICE_REGS();
};
struct cxl_device_regs device_regs;
};
union {
struct {
CXL_COMPONENT_REGS();
};
struct cxl_component_regs component_regs;
};
};
With this arrangement the driver can share component init code with
ports, but when using the registers it can directly reference the
component register block type by name without the 'component_regs'
prefix.
So, map + enumerate can be shared across drivers of different CXL
classes e.g.:
void cxl_setup_device_regs(struct device *dev, void __iomem *base,
struct cxl_device_regs *regs);
void cxl_setup_component_regs(struct device *dev, void __iomem *base,
struct cxl_component_regs *regs);
...while inline usage in the driver need not indicate where the
registers came from:
readl(cxlm->regs.mbox + MBOX_OFFSET);
readl(cxlm->regs.hdm + HDM_OFFSET);
...instead of:
readl(cxlm->regs.device_regs.mbox + MBOX_OFFSET);
readl(cxlm->regs.component_regs.hdm + HDM_OFFSET);
This complexity of the definition in .h yields improvement in code
readability in .c while maintaining type-safety for organization of
setup code. It prepares the implementation to maintain organization in
the face of CXL devices that compose register interfaces consisting of
multiple types.
Given that this new container is named 'regs' rename the common register
base pointer @base, and fixup the kernel-doc for the missing @cxlmd
description.
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/162096971451.1865304.13540251513463515153.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for sharing cxl.h with other generic CXL consumers,
move / consolidate some of the memory device specifics to mem.h.
The motivation for moving out of cxl.h is to maintain least privilege
access to memory-device details since cxl.h is used in multiple files.
The motivation for moving definitions into a new mem.h header is for
code readability and organization. I.e. minimize implementation details
when reading data structures and other definitions.
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162096970932.1865304.14510894426562947262.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
CXL devices identified by the memory-device class code must implement
the Device Command Interface (described in 8.2.9 of the CXL 2.0 spec).
While the driver already maintains a list of commands it supports, there
is still a need to be able to distinguish between commands that the
driver knows about from commands that are optionally supported by the
hardware.
The Command Effects Log (CEL) is specified in the CXL 2.0 specification.
The CEL is one of two types of logs, the other being vendor specific.
They are distinguished in hardware/spec via UUID. The CEL is useful for
2 things:
1. Determine which optional commands are supported by the CXL device.
2. Enumerate any vendor specific commands
The CEL is used by the driver to determine which commands are available
in the hardware and therefore which commands userspace is allowed to
execute. The set of enabled commands might be a subset of commands which
are advertised in UAPI via CXL_MEM_SEND_COMMAND IOCTL.
With the CEL enabling comes a internal flag to indicate a base set of
commands that are enabled regardless of CEL. Such commands are required
for basic interaction with the hardware and thus can be useful in debug
cases, for example if the CEL is corrupted.
The implementation leaves the statically defined table of commands and
supplements it with a bitmap to determine commands that are enabled.
This organization was chosen for the following reasons:
- Smaller memory footprint. Doesn't need a table per device.
- Reduce memory allocation complexity.
- Fixed command IDs to opcode mapping for all devices makes development
and debugging easier.
- Certain helpers are easily achievable, like cxl_for_each_cmd().
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com> (v2)
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> (v3)
Link: https://lore.kernel.org/r/20210217040958.1354670-7-ben.widawsky@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Create the /sys/bus/cxl hierarchy to enumerate:
* Memory Devices (per-endpoint control devices)
* Memory Address Space Devices (platform address ranges with
interleaving, performance, and persistence attributes)
* Memory Regions (active provisioned memory from an address space device
that is in use as System RAM or delegated to libnvdimm as Persistent
Memory regions).
For now, only the per-endpoint control devices are registered on the
'cxl' bus. However, going forward it will provide a mechanism to
coordinate cross-device interleave.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> (v2)
Link: https://lore.kernel.org/r/20210217040958.1354670-4-ben.widawsky@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Provide enough functionality to utilize the mailbox of a memory device.
The mailbox is used to interact with the firmware running on the memory
device. The flow is proven with one implemented command, "identify".
Because the class code has already told the driver this is a memory
device and the identify command is mandatory.
CXL devices contain an array of capabilities that describe the
interactions software can have with the device or firmware running on
the device. A CXL compliant device must implement the device status and
the mailbox capability. Additionally, a CXL compliant memory device must
implement the memory device capability. Each of the capabilities can
[will] provide an offset within the MMIO region for interacting with the
CXL device.
The capabilities tell the driver how to find and map the register space
for CXL Memory Devices. The registers are required to utilize the CXL
spec defined mailbox interface. The spec outlines two mailboxes, primary
and secondary. The secondary mailbox is earmarked for system firmware,
and not handled in this driver.
Primary mailboxes are capable of generating an interrupt when submitting
a background command. That implementation is saved for a later time.
Reported-by: Colin Ian King <colin.king@canonical.com> (coverity)
Reported-by: Dan Carpenter <dan.carpenter@oracle.com> (smatch)
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com> (v2)
Link: https://www.computeexpresslink.org/download-the-specification
Link: https://lore.kernel.org/r/20210217040958.1354670-3-ben.widawsky@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
