linux/arch/s390/pci/pci_bus.c
Niklas Schnelle 14c87ba812 s390/pci: separate zbus registration from scanning
Now that the zbus can be created without being scanned we can go one
step further and make registering a device to a zbus independent from
scanning it. This way the zbus handling becomes much more natural
in that functions can be registered on the zbus to be scanned later more
closely resembling the handling of both real PCI hardware and other
virtual PCI busses like Hyper-V's virtual PCI bus (see for example
drivers/pci/controller/pci-hyperv.c:create_root_hv_pci_bus()).

Having zbus registration separate from scanning allows us to return
fully initialized but still disabled zdevs from zpci_create_device()
which can then be configured just as we would configure a zdev from
standby (minus the SCLP Configure already done by the platform).  There
is still the exception that a PCI function with non-zero devfn can be
plugged before its PCI bus, which depends on the function with zero
devfn, is created. In this case the zdev returend from
zpci_create_device() is still missing its bus, hotplug slot, and
resources which need to be created later but at least it doesn't wait in
the enabled state and can otherwise be treated as initialized.

With this we also separate the initial PCI scan using CLP List PCI
Functions into two phases. In the CLP loop's callback we only register
each function with a virtual zbus creating the latter as needed. Then,
after we have built this virtual PCI topology based on our list of
zbusses, we can make use of the common code functionality to scan each
complete zbus as a separate child bus.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2021-04-12 12:46:42 +02:00

423 lines
9.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2020
*
* Author(s):
* Pierre Morel <pmorel@linux.ibm.com>
*
*/
#define KMSG_COMPONENT "zpci"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/delay.h>
#include <linux/seq_file.h>
#include <linux/jump_label.h>
#include <linux/pci.h>
#include <linux/printk.h>
#include <asm/pci_clp.h>
#include <asm/pci_dma.h>
#include "pci_bus.h"
#include "pci_iov.h"
static LIST_HEAD(zbus_list);
static DEFINE_MUTEX(zbus_list_lock);
static int zpci_nb_devices;
/* zpci_bus_prepare_device - Prepare a zPCI function for scanning
* @zdev: the zPCI function to be prepared
*
* The PCI resources for the function are set up and added to its zbus and the
* function is enabled. The function must be added to a zbus which must have
* a PCI bus created. If an error occurs the zPCI function is not enabled.
*
* Return: 0 on success, an error code otherwise
*/
static int zpci_bus_prepare_device(struct zpci_dev *zdev)
{
struct resource_entry *window, *n;
struct resource *res;
int rc;
if (!zdev_enabled(zdev)) {
rc = zpci_enable_device(zdev);
if (rc)
return rc;
}
if (!zdev->has_resources) {
zpci_setup_bus_resources(zdev, &zdev->zbus->resources);
resource_list_for_each_entry_safe(window, n, &zdev->zbus->resources) {
res = window->res;
pci_bus_add_resource(zdev->zbus->bus, res, 0);
}
}
return 0;
}
/* zpci_bus_scan_device - Scan a single device adding it to the PCI core
* @zdev: the zdev to be scanned
*
* Scans the PCI function making it available to the common PCI code.
*
* Return: 0 on success, an error value otherwise
*/
int zpci_bus_scan_device(struct zpci_dev *zdev)
{
struct pci_dev *pdev;
int rc;
rc = zpci_bus_prepare_device(zdev);
if (rc)
return rc;
pdev = pci_scan_single_device(zdev->zbus->bus, zdev->devfn);
if (!pdev)
return -ENODEV;
pci_bus_add_device(pdev);
pci_lock_rescan_remove();
pci_bus_add_devices(zdev->zbus->bus);
pci_unlock_rescan_remove();
return 0;
}
/* zpci_bus_remove_device - Removes the given zdev from the PCI core
* @zdev: the zdev to be removed from the PCI core
* @set_error: if true the device's error state is set to permanent failure
*
* Sets a zPCI device to a configured but offline state; the zPCI
* device is still accessible through its hotplug slot and the zPCI
* API but is removed from the common code PCI bus, making it
* no longer available to drivers.
*/
void zpci_bus_remove_device(struct zpci_dev *zdev, bool set_error)
{
struct zpci_bus *zbus = zdev->zbus;
struct pci_dev *pdev;
if (!zdev->zbus->bus)
return;
pdev = pci_get_slot(zbus->bus, zdev->devfn);
if (pdev) {
if (set_error)
pdev->error_state = pci_channel_io_perm_failure;
if (pdev->is_virtfn) {
zpci_iov_remove_virtfn(pdev, zdev->vfn);
/* balance pci_get_slot */
pci_dev_put(pdev);
return;
}
pci_stop_and_remove_bus_device_locked(pdev);
/* balance pci_get_slot */
pci_dev_put(pdev);
}
}
/* zpci_bus_scan_bus - Scan all configured zPCI functions on the bus
* @zbus: the zbus to be scanned
*
* Enables and scans all PCI functions on the bus making them available to the
* common PCI code. If there is no function 0 on the zbus nothing is scanned. If
* a function does not have a slot yet because it was added to the zbus before
* function 0 the slot is created. If a PCI function fails to be initialized
* an error will be returned but attempts will still be made for all other
* functions on the bus.
*
* Return: 0 on success, an error value otherwise
*/
int zpci_bus_scan_bus(struct zpci_bus *zbus)
{
struct zpci_dev *zdev;
int devfn, rc, ret = 0;
if (!zbus->function[0])
return 0;
for (devfn = 0; devfn < ZPCI_FUNCTIONS_PER_BUS; devfn++) {
zdev = zbus->function[devfn];
if (zdev && zdev->state == ZPCI_FN_STATE_CONFIGURED) {
rc = zpci_bus_prepare_device(zdev);
if (rc)
ret = -EIO;
}
}
pci_lock_rescan_remove();
pci_scan_child_bus(zbus->bus);
pci_bus_add_devices(zbus->bus);
pci_unlock_rescan_remove();
return ret;
}
/* zpci_bus_scan_busses - Scan all registered busses
*
* Scan all available zbusses
*
*/
void zpci_bus_scan_busses(void)
{
struct zpci_bus *zbus = NULL;
mutex_lock(&zbus_list_lock);
list_for_each_entry(zbus, &zbus_list, bus_next) {
zpci_bus_scan_bus(zbus);
cond_resched();
}
mutex_unlock(&zbus_list_lock);
}
/* zpci_bus_create_pci_bus - Create the PCI bus associated with this zbus
* @zbus: the zbus holding the zdevices
* @f0: function 0 of the bus
* @ops: the pci operations
*
* Function zero is taken as a parameter as this is used to determine the
* domain, multifunction property and maximum bus speed of the entire bus.
*
* Return: 0 on success, an error code otherwise
*/
static int zpci_bus_create_pci_bus(struct zpci_bus *zbus, struct zpci_dev *f0, struct pci_ops *ops)
{
struct pci_bus *bus;
int domain;
domain = zpci_alloc_domain((u16)f0->uid);
if (domain < 0)
return domain;
zbus->domain_nr = domain;
zbus->multifunction = f0->rid_available;
zbus->max_bus_speed = f0->max_bus_speed;
/*
* Note that the zbus->resources are taken over and zbus->resources
* is empty after a successful call
*/
bus = pci_create_root_bus(NULL, ZPCI_BUS_NR, ops, zbus, &zbus->resources);
if (!bus) {
zpci_free_domain(zbus->domain_nr);
return -EFAULT;
}
zbus->bus = bus;
pci_bus_add_devices(bus);
return 0;
}
static void zpci_bus_release(struct kref *kref)
{
struct zpci_bus *zbus = container_of(kref, struct zpci_bus, kref);
if (zbus->bus) {
pci_lock_rescan_remove();
pci_stop_root_bus(zbus->bus);
zpci_free_domain(zbus->domain_nr);
pci_free_resource_list(&zbus->resources);
pci_remove_root_bus(zbus->bus);
pci_unlock_rescan_remove();
}
mutex_lock(&zbus_list_lock);
list_del(&zbus->bus_next);
mutex_unlock(&zbus_list_lock);
kfree(zbus);
}
static void zpci_bus_put(struct zpci_bus *zbus)
{
kref_put(&zbus->kref, zpci_bus_release);
}
static struct zpci_bus *zpci_bus_get(int pchid)
{
struct zpci_bus *zbus;
mutex_lock(&zbus_list_lock);
list_for_each_entry(zbus, &zbus_list, bus_next) {
if (pchid == zbus->pchid) {
kref_get(&zbus->kref);
goto out_unlock;
}
}
zbus = NULL;
out_unlock:
mutex_unlock(&zbus_list_lock);
return zbus;
}
static struct zpci_bus *zpci_bus_alloc(int pchid)
{
struct zpci_bus *zbus;
zbus = kzalloc(sizeof(*zbus), GFP_KERNEL);
if (!zbus)
return NULL;
zbus->pchid = pchid;
INIT_LIST_HEAD(&zbus->bus_next);
mutex_lock(&zbus_list_lock);
list_add_tail(&zbus->bus_next, &zbus_list);
mutex_unlock(&zbus_list_lock);
kref_init(&zbus->kref);
INIT_LIST_HEAD(&zbus->resources);
zbus->bus_resource.start = 0;
zbus->bus_resource.end = ZPCI_BUS_NR;
zbus->bus_resource.flags = IORESOURCE_BUS;
pci_add_resource(&zbus->resources, &zbus->bus_resource);
return zbus;
}
void pcibios_bus_add_device(struct pci_dev *pdev)
{
struct zpci_dev *zdev = to_zpci(pdev);
/*
* With pdev->no_vf_scan the common PCI probing code does not
* perform PF/VF linking.
*/
if (zdev->vfn) {
zpci_iov_setup_virtfn(zdev->zbus, pdev, zdev->vfn);
pdev->no_command_memory = 1;
}
}
/* zpci_bus_create_hotplug_slots - Add hotplug slot(s) for device added to bus
* @zdev: the zPCI device that was newly added
*
* Add the hotplug slot(s) for the newly added PCI function. Normally this is
* simply the slot for the function itself. If however we are adding the
* function 0 on a zbus, it might be that we already registered functions on
* that zbus but could not create their hotplug slots yet so add those now too.
*
* Return: 0 on success, an error code otherwise
*/
static int zpci_bus_create_hotplug_slots(struct zpci_dev *zdev)
{
struct zpci_bus *zbus = zdev->zbus;
int devfn, rc = 0;
rc = zpci_init_slot(zdev);
if (rc)
return rc;
zdev->has_hp_slot = 1;
if (zdev->devfn == 0 && zbus->multifunction) {
/* Now that function 0 is there we can finally create the
* hotplug slots for those functions with devfn != 0 that have
* been parked in zbus->function[] waiting for us to be able to
* create the PCI bus.
*/
for (devfn = 1; devfn < ZPCI_FUNCTIONS_PER_BUS; devfn++) {
zdev = zbus->function[devfn];
if (zdev && !zdev->has_hp_slot) {
rc = zpci_init_slot(zdev);
if (rc)
return rc;
zdev->has_hp_slot = 1;
}
}
}
return rc;
}
static int zpci_bus_add_device(struct zpci_bus *zbus, struct zpci_dev *zdev)
{
int rc = -EINVAL;
zdev->zbus = zbus;
if (zbus->function[zdev->devfn]) {
pr_err("devfn %04x is already assigned\n", zdev->devfn);
return rc;
}
zbus->function[zdev->devfn] = zdev;
zpci_nb_devices++;
if (zbus->bus) {
if (zbus->multifunction && !zdev->rid_available) {
WARN_ONCE(1, "rid_available not set for multifunction\n");
goto error;
}
zpci_bus_create_hotplug_slots(zdev);
} else {
/* Hotplug slot will be created once function 0 appears */
zbus->multifunction = 1;
}
return 0;
error:
zbus->function[zdev->devfn] = NULL;
zpci_nb_devices--;
return rc;
}
int zpci_bus_device_register(struct zpci_dev *zdev, struct pci_ops *ops)
{
struct zpci_bus *zbus = NULL;
int rc = -EBADF;
if (zpci_nb_devices == ZPCI_NR_DEVICES) {
pr_warn("Adding PCI function %08x failed because the configured limit of %d is reached\n",
zdev->fid, ZPCI_NR_DEVICES);
return -ENOSPC;
}
if (zdev->devfn >= ZPCI_FUNCTIONS_PER_BUS)
return -EINVAL;
if (!s390_pci_no_rid && zdev->rid_available)
zbus = zpci_bus_get(zdev->pchid);
if (!zbus) {
zbus = zpci_bus_alloc(zdev->pchid);
if (!zbus)
return -ENOMEM;
}
if (zdev->devfn == 0) {
rc = zpci_bus_create_pci_bus(zbus, zdev, ops);
if (rc)
goto error;
}
rc = zpci_bus_add_device(zbus, zdev);
if (rc)
goto error;
return 0;
error:
pr_err("Adding PCI function %08x failed\n", zdev->fid);
zpci_bus_put(zbus);
return rc;
}
void zpci_bus_device_unregister(struct zpci_dev *zdev)
{
struct zpci_bus *zbus = zdev->zbus;
zpci_nb_devices--;
zbus->function[zdev->devfn] = NULL;
zpci_bus_put(zbus);
}