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cxl/acpi: Enumerate host bridge root ports 

While the resources enumerated by the CEDT.CFMWS identify a cxl_port
with host bridges as downstream ports, host bridges themselves are
upstream ports that decode to downstream ports represented by PCIe Root
Ports. Walk the PCIe Root Ports connected to a CXL Host Bridge,
identified by the ACPI0016 _HID, and add each one as a cxl_dport of the
host bridge cxl_port.

For now, component registers are not enumerated, only the first order
uport / dport relationships.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325451145.2293126.10149150938788969381.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2021-06-09 09:01:51 -07:00
parent 7d4b5ca2e2
commit 3b94ce7b7b
1 changed files with 92 additions and 1 deletions
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93
drivers/cxl/acpi.c
View File

@ -5,8 +5,51 @@
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/pci.h>
#include "cxl.h"
struct cxl_walk_context {
struct device *dev;
struct pci_bus *root;
struct cxl_port *port;
int error;
int count;
};
static int match_add_root_ports(struct pci_dev *pdev, void *data)
{
struct cxl_walk_context *ctx = data;
struct pci_bus *root_bus = ctx->root;
struct cxl_port *port = ctx->port;
int type = pci_pcie_type(pdev);
struct device *dev = ctx->dev;
u32 lnkcap, port_num;
int rc;
if (pdev->bus != root_bus)
return 0;
if (!pci_is_pcie(pdev))
return 0;
if (type != PCI_EXP_TYPE_ROOT_PORT)
return 0;
if (pci_read_config_dword(pdev, pci_pcie_cap(pdev) + PCI_EXP_LNKCAP,
&lnkcap) != PCIBIOS_SUCCESSFUL)
return 0;
/* TODO walk DVSEC to find component register base */
port_num = FIELD_GET(PCI_EXP_LNKCAP_PN, lnkcap);
rc = cxl_add_dport(port, &pdev->dev, port_num, CXL_RESOURCE_NONE);
if (rc) {
ctx->error = rc;
return rc;
}
ctx->count++;
dev_dbg(dev, "add dport%d: %s\n", port_num, dev_name(&pdev->dev));
return 0;
}
static struct acpi_device *to_cxl_host_bridge(struct device *dev)
{
struct acpi_device *adev = to_acpi_device(dev);
@ -16,6 +59,44 @@ static struct acpi_device *to_cxl_host_bridge(struct device *dev)
return NULL;
}
/*
* A host bridge is a dport to a CFMWS decode and it is a uport to the
* dport (PCIe Root Ports) in the host bridge.
*/
static int add_host_bridge_uport(struct device *match, void *arg)
{
struct acpi_device *bridge = to_cxl_host_bridge(match);
struct cxl_port *root_port = arg;
struct device *host = root_port->dev.parent;
struct acpi_pci_root *pci_root;
struct cxl_walk_context ctx;
struct cxl_port *port;
if (!bridge)
return 0;
pci_root = acpi_pci_find_root(bridge->handle);
if (!pci_root)
return -ENXIO;
/* TODO: fold in CEDT.CHBS retrieval */
port = devm_cxl_add_port(host, match, CXL_RESOURCE_NONE, root_port);
if (IS_ERR(port))
return PTR_ERR(port);
dev_dbg(host, "%s: add: %s\n", dev_name(match), dev_name(&port->dev));
ctx = (struct cxl_walk_context){
.dev = host,
.root = pci_root->bus,
.port = port,
};
pci_walk_bus(pci_root->bus, match_add_root_ports, &ctx);
if (ctx.count == 0)
return -ENODEV;
return ctx.error;
}
static int add_host_bridge_dport(struct device *match, void *arg)
{
int rc;
@ -48,6 +129,7 @@ static int add_host_bridge_dport(struct device *match, void *arg)
static int cxl_acpi_probe(struct platform_device *pdev)
{
int rc;
struct cxl_port *root_port;
struct device *host = &pdev->dev;
struct acpi_device *adev = ACPI_COMPANION(host);
@ -57,8 +139,17 @@ static int cxl_acpi_probe(struct platform_device *pdev)
return PTR_ERR(root_port);
dev_dbg(host, "add: %s\n", dev_name(&root_port->dev));
return bus_for_each_dev(adev->dev.bus, NULL, root_port,
rc = bus_for_each_dev(adev->dev.bus, NULL, root_port,
add_host_bridge_dport);
if (rc)
return rc;
/*
* Root level scanned with host-bridge as dports, now scan host-bridges
* for their role as CXL uports to their CXL-capable PCIe Root Ports.
*/
return bus_for_each_dev(adev->dev.bus, NULL, root_port,
add_host_bridge_uport);
}
static const struct acpi_device_id cxl_acpi_ids[] = {