Re: [PATCH 06/24] RISC-V: ACPI: Add PCI functions to build ACPI core

Conor Dooley
2023-02-08T21:27:11Z

[-- Attachment #1: Type: text/plain, Size: 6736 bytes --]

On Mon, Jan 30, 2023 at 11:52:07PM +0530, Sunil V L wrote:
> When CONFIG_PCI is enabled, ACPI core expects few arch
> functions related to PCI. Add those functions so that
> ACPI core gets build. These are levraged from arm64.
>
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
> arch/riscv/kernel/Makefile | 1 +
> arch/riscv/kernel/pci.c | 173 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 174 insertions(+)
> create mode 100644 arch/riscv/kernel/pci.c

> diff --git a/arch/riscv/kernel/pci.c b/arch/riscv/kernel/pci.c
> new file mode 100644
> index 000000000000..3388af3a67a0
> --- /dev/null
> +++ b/arch/riscv/kernel/pci.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Code borrowed from ARM64
> + *
> + * Copyright (C) 2003 Anton Blanchard <anton@au.ibm.com>, IBM
> + * Copyright (C) 2014 ARM Ltd.
> + * Copyright (C) 2022-2023 Ventana Micro System Inc.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/mm.h>
> +#include <linux/pci.h>
> +#include <linux/pci-acpi.h>
> +#include <linux/pci-ecam.h>
> +
> +#ifdef CONFIG_ACPI

Quickly checking against ARM64, they do not wrap the read/write
functions in this ifdef, so why do we need to do so?

> +/*
> + * raw_pci_read/write - Platform-specific PCI config space access.
> + */
> +int raw_pci_read(unsigned int domain, unsigned int bus,
> + unsigned int devfn, int reg, int len, u32 *val)
> +{
> + struct pci_bus *b = pci_find_bus(domain, bus);
> +
> + if (!b)
> + return PCIBIOS_DEVICE_NOT_FOUND;
> + return b->ops->read(b, devfn, reg, len, val);

A newline before the return would be appreciated by my eyes :)

> +}
> +
> +int raw_pci_write(unsigned int domain, unsigned int bus,
> + unsigned int devfn, int reg, int len, u32 val)

Also, both read and write functions here appear to have incorrect
alignment on the second lines.

> +{
> + struct pci_bus *b = pci_find_bus(domain, bus);
> +
> + if (!b)
> + return PCIBIOS_DEVICE_NOT_FOUND;
> + return b->ops->write(b, devfn, reg, len, val);
> +}
> +
> +

Extra newline here too, looks to be exactly where you deleted the numa
stuff from arm64 ;)

> +struct acpi_pci_generic_root_info {
> + struct acpi_pci_root_info common;
> + struct pci_config_window *cfg; /* config space mapping */
> +};
> +
> +int acpi_pci_bus_find_domain_nr(struct pci_bus *bus)
> +{
> + struct pci_config_window *cfg = bus->sysdata;
> + struct acpi_device *adev = to_acpi_device(cfg->parent);
> + struct acpi_pci_root *root = acpi_driver_data(adev);
> +
> + return root->segment;
> +}
> +
> +static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)

Rhetorical question perhaps, but what does "ci" mean?

> +{
> + struct resource_entry *entry, *tmp;
> + int status;
> +
> + status = acpi_pci_probe_root_resources(ci);
> + resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
> + if (!(entry->res->flags & IORESOURCE_WINDOW))
> + resource_list_destroy_entry(entry);
> + }
> + return status;

Perhaps that extra newline from above could migrate down to the line
above the return here.

> +}
> +
> +/*
> + * Lookup the bus range for the domain in MCFG, and set up config space
> + * mapping.
> + */
> +static struct pci_config_window *
> +pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)

This all fits on 1 line.

> +{
> + struct device *dev = &root->device->dev;
> + struct resource *bus_res = &root->secondary;
> + u16 seg = root->segment;
> + const struct pci_ecam_ops *ecam_ops;
> + struct resource cfgres;
> + struct acpi_device *adev;
> + struct pci_config_window *cfg;
> + int ret;
> +
> + ret = pci_mcfg_lookup(root, &cfgres, &ecam_ops);
> + if (ret) {
> + dev_err(dev, "%04x:%pR ECAM region not found\n", seg, bus_res);
> + return NULL;
> + }
> +
> + adev = acpi_resource_consumer(&cfgres);
> + if (adev)
> + dev_info(dev, "ECAM area %pR reserved by %s\n", &cfgres,
> + dev_name(&adev->dev));
> + else
> + dev_warn(dev, FW_BUG "ECAM area %pR not reserved in ACPI namespace\n",
> + &cfgres);
> +
> + cfg = pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
> + if (IS_ERR(cfg)) {
> + dev_err(dev, "%04x:%pR error %ld mapping ECAM\n", seg, bus_res,
> + PTR_ERR(cfg));
> + return NULL;
> + }
> +
> + return cfg;
> +}
> +
> +/* release_info: free resources allocated by init_info */

The fact that you haven't picked a consistent comment style for this
functions really bothers my OCD. Yes, it may be copy-paste from arm64,
but since this is "new code" I don't think there's harm in at least
*starting* with something that looks cohesive.

> +static void pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
> +{
> + struct acpi_pci_generic_root_info *ri;
> +
> + ri = container_of(ci, struct acpi_pci_generic_root_info, common);
> + pci_ecam_free(ri->cfg);
> + kfree(ci->ops);
> + kfree(ri);
> +}
> +
> +

Extra newline here.

> +/* Interface called from ACPI code to setup PCI host controller */
> +struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
> +{
> + struct acpi_pci_generic_root_info *ri;
> + struct pci_bus *bus, *child;
> + struct acpi_pci_root_ops *root_ops;
> + struct pci_host_bridge *host;
> +
> + ri = kzalloc(sizeof(*ri), GFP_KERNEL);
> + if (!ri)
> + return NULL;
> +
> + root_ops = kzalloc(sizeof(*root_ops), GFP_KERNEL);
> + if (!root_ops) {
> + kfree(ri);
> + return NULL;
> + }
> +
> + ri->cfg = pci_acpi_setup_ecam_mapping(root);
> + if (!ri->cfg) {
> + kfree(ri);
> + kfree(root_ops);
> + return NULL;
> + }
> +
> + root_ops->release_info = pci_acpi_generic_release_info;
> + root_ops->prepare_resources = pci_acpi_root_prepare_resources;
> + root_ops->pci_ops = (struct pci_ops *)&ri->cfg->ops->pci_ops;
> + bus = acpi_pci_root_create(root, root_ops, &ri->common, ri->cfg);
> + if (!bus)
> + return NULL;
> +
> + /* If we must preserve the resource configuration, claim now */
> + host = pci_find_host_bridge(bus);
> + if (host->preserve_config)
> + pci_bus_claim_resources(bus);
> +
> + /*
> + * Assign whatever was left unassigned. If we didn't claim above,
> + * this will reassign everything.
> + */
> + pci_assign_unassigned_root_bus_resources(bus);
> +
> + list_for_each_entry(child, &bus->children, node)
> + pcie_bus_configure_settings(child);
> +
> + return bus;
> +}

Anyways, this does look to be "leveraged from arm64" as you say and I
only had minor nits to comment about...
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Cheers,
Conor.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]