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| author | Dan Williams <dan.j.williams@intel.com> | 2021-06-09 09:43:29 -0700 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2021-06-09 18:02:39 -0700 |
| commit | 40ba17afdfabb01688c61565dbe02a916241bc05 (patch) | |
| tree | 2970c531795251fb14b6562efac1a88517c72dda /drivers/cxl/acpi.c | |
| parent | 3b94ce7b7bc1b436465a93f19a50e0b495b429a1 (diff) | |
cxl/acpi: Introduce cxl_decoder objects
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>
Diffstat (limited to 'drivers/cxl/acpi.c')
| -rw-r--r-- | drivers/cxl/acpi.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index 1f075dffc042..be357eea552c 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -70,6 +70,7 @@ static int add_host_bridge_uport(struct device *match, void *arg) struct device *host = root_port->dev.parent; struct acpi_pci_root *pci_root; struct cxl_walk_context ctx; + struct cxl_decoder *cxld; struct cxl_port *port; if (!bridge) @@ -94,7 +95,24 @@ static int add_host_bridge_uport(struct device *match, void *arg) if (ctx.count == 0) return -ENODEV; - return ctx.error; + if (ctx.error) + return ctx.error; + + /* TODO: Scan CHBCR for HDM Decoder resources */ + + /* + * In the single-port host-bridge case there are no HDM decoders + * in the CHBCR and a 1:1 passthrough decode is implied. + */ + if (ctx.count == 1) { + cxld = devm_cxl_add_passthrough_decoder(host, port); + if (IS_ERR(cxld)) + return PTR_ERR(cxld); + + dev_dbg(host, "add: %s\n", dev_name(&cxld->dev)); + } + + return 0; } static int add_host_bridge_dport(struct device *match, void *arg) |