On 21-06-05 23:05:04, Dan Williams wrote: > 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 the ACPI identifies the address space and interleave > configuration for CXL Memory. > > In addition to identifying the 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 reported by _CRS for PCI host bridges. Specifically ACPI > publishes a table, CXL Early Discovery Table (CEDT), which includes a > list of CXL Memory resource, 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. > > Co-developed-by: Alison Schofield <alison.schofield@xxxxxxxxx> > Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > Documentation/ABI/testing/sysfs-bus-cxl | 11 ++ > drivers/cxl/Kconfig | 15 +++ > drivers/cxl/Makefile | 2 > drivers/cxl/acpi.c | 39 ++++++++ > drivers/cxl/core.c | 160 +++++++++++++++++++++++++++++++ > drivers/cxl/cxl.h | 23 ++++ > 6 files changed, 250 insertions(+) > create mode 100644 drivers/cxl/acpi.c > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl > index 2fe7490ad6a8..fb996ced7629 100644 > --- a/Documentation/ABI/testing/sysfs-bus-cxl > +++ b/Documentation/ABI/testing/sysfs-bus-cxl > @@ -24,3 +24,14 @@ Description: > (RO) "Persistent Only Capacity" as bytes. Represents the > identically named field in the Identify Memory Device Output > Payload in the CXL-2.0 specification. > + > +What: /sys/bus/cxl/devices/portX/uport > +Date: May, 2021 > +KernelVersion: v5.14 > +Contact: linux-cxl@xxxxxxxxxxxxxxx > +Description: > + CXL port objects are enumerated from either a platform firmware > + device (ACPI0017 and ACPI0016) or PCIe switch upstream port with > + CXL component registers. The 'uport' symlink connects the CXL > + portX object to the device that published the CXL port > + capability. > diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig > index 5483ba92b6da..d2573f6aef91 100644 > --- a/drivers/cxl/Kconfig > +++ b/drivers/cxl/Kconfig > @@ -45,4 +45,19 @@ config CXL_MEM_RAW_COMMANDS > potential impact to memory currently in use by the kernel. > > If developing CXL hardware or the driver say Y, otherwise say N. > + > +config CXL_ACPI > + tristate "CXL ACPI: Platform Support" > + depends on ACPI > + help > + Enable support for host managed device memory (HDM) resources > + published by a platform's ACPI CXL memory layout description. See > + Chapter 9.14.1 CXL Early Discovery Table (CEDT) in the CXL 2.0 > + specification, and CXL Fixed Memory Window Structures (CEDT.CFMWS) > + (https://www.computeexpresslink.org/spec-landing). The CXL core > + consumes these resource to publish the root of a cxl_port decode > + hierarchy to map regions that represent System RAM, or Persistent > + Memory regions to be managed by LIBNVDIMM. > + > + If unsure say 'm'. > endif > diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile > index d9d282dc15be..a29efb3e8ad2 100644 > --- a/drivers/cxl/Makefile > +++ b/drivers/cxl/Makefile > @@ -1,7 +1,9 @@ > # SPDX-License-Identifier: GPL-2.0 > obj-$(CONFIG_CXL_BUS) += cxl_core.o > obj-$(CONFIG_CXL_MEM) += cxl_pci.o > +obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o > > ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=CXL > cxl_core-y := core.o > cxl_pci-y := pci.o > +cxl_acpi-y := acpi.o > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c > new file mode 100644 > index 000000000000..556d25ab6966 > --- /dev/null > +++ b/drivers/cxl/acpi.c > @@ -0,0 +1,39 @@ > +// 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 "cxl.h" > + > +static int cxl_acpi_probe(struct platform_device *pdev) > +{ > + struct cxl_port *root_port; > + struct device *host = &pdev->dev; > + > + 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)); > + > + return 0; > +} > + > +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); > diff --git a/drivers/cxl/core.c b/drivers/cxl/core.c > index 853666d8a9f5..dbbb34618d7d 100644 > --- a/drivers/cxl/core.c > +++ b/drivers/cxl/core.c > @@ -4,6 +4,8 @@ > #include <linux/device.h> > #include <linux/module.h> > #include <linux/pci.h> > +#include <linux/slab.h> > +#include <linux/idr.h> > #include "cxl.h" > > /** > @@ -13,6 +15,164 @@ > * point for cross-device interleave coordination through cxl ports. > */ > > +static DEFINE_IDA(cxl_port_ida); > + > +static ssize_t devtype_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + return sysfs_emit(buf, "%s\n", dev->type->name); > +} > +static DEVICE_ATTR_RO(devtype); > + > +static struct attribute *cxl_base_attributes[] = { > + &dev_attr_devtype.attr, > + NULL, > +}; > + > +static struct attribute_group cxl_base_attribute_group = { > + .attrs = cxl_base_attributes, > +}; > + > +static void cxl_port_release(struct device *dev) > +{ > + struct cxl_port *port = to_cxl_port(dev); > + > + ida_free(&cxl_port_ida, port->id); > + kfree(port); > +} > + > +static const struct attribute_group *cxl_port_attribute_groups[] = { > + &cxl_base_attribute_group, > + NULL, > +}; > + > +static const struct device_type cxl_port_type = { > + .name = "cxl_port", > + .release = cxl_port_release, > + .groups = cxl_port_attribute_groups, > +}; > + > +struct cxl_port *to_cxl_port(struct device *dev) > +{ > + if (dev_WARN_ONCE(dev, dev->type != &cxl_port_type, > + "not a cxl_port device\n")) > + return NULL; > + return container_of(dev, struct cxl_port, dev); > +} > + > +static void unregister_dev(void *dev) > +{ > + device_unregister(dev); > +} > + > +static void cxl_unlink_uport(void *_port) > +{ > + struct cxl_port *port = _port; > + > + sysfs_remove_link(&port->dev.kobj, "uport"); > +} > + > +static int devm_cxl_link_uport(struct device *host, struct cxl_port *port) > +{ > + int rc; > + > + rc = sysfs_create_link(&port->dev.kobj, &port->uport->kobj, "uport"); > + if (rc) > + return rc; > + return devm_add_action_or_reset(host, cxl_unlink_uport, port); > +} > + > +static struct cxl_port *cxl_port_alloc(struct device *uport, > + resource_size_t component_reg_phys, > + struct cxl_port *parent_port) > +{ > + struct cxl_port *port; > + struct device *dev; > + int rc; > + > + port = kzalloc(sizeof(*port), GFP_KERNEL); > + if (!port) > + return ERR_PTR(-ENOMEM); > + > + rc = ida_alloc(&cxl_port_ida, GFP_KERNEL); > + if (rc < 0) > + goto err; > + port->id = rc; > + > + /* > + * The top-level cxl_port "cxl_root" does not have a cxl_port as > + * its parent and it does not have any corresponding component > + * registers as its decode is described by a fixed platform > + * description. > + */ > + dev = &port->dev; > + if (parent_port) > + dev->parent = &parent_port->dev; > + else > + dev->parent = uport; > + > + port->uport = uport; > + port->component_reg_phys = component_reg_phys; > + > + device_initialize(dev); > + device_set_pm_not_required(dev); > + dev->bus = &cxl_bus_type; > + dev->type = &cxl_port_type; > + > + return port; > + > +err: > + kfree(port); > + return ERR_PTR(rc); > +} > + > +/** > + * devm_cxl_add_port - register a cxl_port in CXL memory decode hierarchy > + * @host: host device for devm operations > + * @uport: "physical" device implementing this upstream port > + * @component_reg_phys: (optional) for configurable cxl_port instances > + * @parent_port: next hop up in the CXL memory decode hierarchy > + */ > +struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport, > + resource_size_t component_reg_phys, > + struct cxl_port *parent_port) > +{ > + struct cxl_port *port; > + struct device *dev; > + int rc; > + > + port = cxl_port_alloc(uport, component_reg_phys, parent_port); > + if (IS_ERR(port)) > + return port; > + > + dev = &port->dev; > + if (parent_port) > + rc = dev_set_name(dev, "port%d", port->id); > + else > + rc = dev_set_name(dev, "root%d", port->id); > + if (rc) > + goto err; > + > + rc = device_add(dev); > + if (rc) > + goto err; > + > + rc = devm_add_action_or_reset(host, unregister_dev, dev); > + if (rc) > + return ERR_PTR(rc); > + > + rc = devm_cxl_link_uport(host, port); > + if (rc) > + return ERR_PTR(rc); > + > + return port; > + > +err: > + put_device(dev); > + return ERR_PTR(rc); > +} > +EXPORT_SYMBOL_GPL(devm_cxl_add_port); > + > /** > * cxl_probe_component_regs() - Detect CXL Component register blocks > * @dev: Host device of the @base mapping > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index 2c47e9cffd44..46c81165c210 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -145,5 +145,28 @@ int cxl_map_device_regs(struct pci_dev *pdev, > struct cxl_device_regs *regs, > struct cxl_register_map *map); > > +#define CXL_RESOURCE_NONE ((resource_size_t) -1) > + > +/** > + * struct cxl_port - logical collection of upstream port devices and > + * downstream port devices to construct a CXL memory > + * decode hierarchy. > + * @dev: this port's device > + * @uport: PCI or platform device implementing the upstream port capability > + * @id: id for port device-name > + * @component_regs_phys: component register capability base address (optional) > + */ > +struct cxl_port { > + struct device dev; > + struct device *uport; > + int id; > + resource_size_t component_reg_phys; > +}; > + I think the new kernel doc info needs to be added in the Documentation/driver-api/cxl/ somewhere. We haven't yet told sphinx about this file. > +struct cxl_port *to_cxl_port(struct device *dev); > +struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport, > + resource_size_t component_reg_phys, > + struct cxl_port *parent_port); > + > extern struct bus_type cxl_bus_type; > #endif /* __CXL_H__ */ >
