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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2021 Intel Corporation. All rights reserved. */
#include <linux/platform_device.h>
#include <linux/module.h>
#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);
if (strcmp(acpi_device_hid(adev), "ACPI0016") == 0)
return adev;
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_decoder *cxld;
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;
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)
{
int rc;
acpi_status status;
unsigned long long uid;
struct cxl_port *root_port = arg;
struct device *host = root_port->dev.parent;
struct acpi_device *bridge = to_cxl_host_bridge(match);
if (!bridge)
return 0;
status = acpi_evaluate_integer(bridge->handle, METHOD_NAME__UID, NULL,
&uid);
if (status != AE_OK) {
dev_err(host, "unable to retrieve _UID of %s\n",
dev_name(match));
return -ENODEV;
}
rc = cxl_add_dport(root_port, match, uid, CXL_RESOURCE_NONE);
if (rc) {
dev_err(host, "failed to add downstream port: %s\n",
dev_name(match));
return rc;
}
dev_dbg(host, "add dport%llu: %s\n", uid, dev_name(match));
return 0;
}
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);
root_port = devm_cxl_add_port(host, host, CXL_RESOURCE_NONE, NULL);
if (IS_ERR(root_port))
return PTR_ERR(root_port);
dev_dbg(host, "add: %s\n", dev_name(&root_port->dev));
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[] = {
{ "ACPI0017", 0 },
{ "", 0 },
};
MODULE_DEVICE_TABLE(acpi, cxl_acpi_ids);
static struct platform_driver cxl_acpi_driver = {
.probe = cxl_acpi_probe,
.driver = {
.name = KBUILD_MODNAME,
.acpi_match_table = cxl_acpi_ids,
},
};
module_platform_driver(cxl_acpi_driver);
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(CXL);
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