linux/drivers/pci/pcie/portdrv_core.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Purpose:	PCI Express Port Bus Driver's Core Functions
 *
 * Copyright (C) 2004 Intel
 * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com)
 */

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/aer.h>

#include "../pci.h"
#include "portdrv.h"

struct portdrv_service_data {
	struct pcie_port_service_driver *drv;
	struct device *dev;
	u32 service;
};

/**
 * release_pcie_device - free PCI Express port service device structure
 * @dev: Port service device to release
 *
 * Invoked automatically when device is being removed in response to
 * device_unregister(dev).  Release all resources being claimed.
 */
static void release_pcie_device(struct device *dev)
{
	kfree(to_pcie_device(dev));
}

/*
 * Fill in *pme, *aer, *dpc with the relevant Interrupt Message Numbers if
 * services are enabled in "mask".  Return the number of MSI/MSI-X vectors
 * required to accommodate the largest Message Number.
 */
static int pcie_message_numbers(struct pci_dev *dev, int mask,
				u32 *pme, u32 *aer, u32 *dpc)
{
	u32 nvec = 0, pos;
	u16 reg16;

	/*
	 * The Interrupt Message Number indicates which vector is used, i.e.,
	 * the MSI-X table entry or the MSI offset between the base Message
	 * Data and the generated interrupt message.  See PCIe r3.1, sec
	 * 7.8.2, 7.10.10, 7.31.2.
	 */

	if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
		    PCIE_PORT_SERVICE_BWNOTIF)) {
		pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
		*pme = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
		nvec = *pme + 1;
	}

#ifdef CONFIG_PCIEAER
	if (mask & PCIE_PORT_SERVICE_AER) {
		u32 reg32;

		pos = dev->aer_cap;
		if (pos) {
			pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS,
					      &reg32);
			*aer = (reg32 & PCI_ERR_ROOT_AER_IRQ) >> 27;
			nvec = max(nvec, *aer + 1);
		}
	}
#endif

	if (mask & PCIE_PORT_SERVICE_DPC) {
		pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC);
		if (pos) {
			pci_read_config_word(dev, pos + PCI_EXP_DPC_CAP,
					     &reg16);
			*dpc = reg16 & PCI_EXP_DPC_IRQ;
			nvec = max(nvec, *dpc + 1);
		}
	}

	return nvec;
}

/**
 * pcie_port_enable_irq_vec - try to set up MSI-X or MSI as interrupt mode
 * for given port
 * @dev: PCI Express port to handle
 * @irqs: Array of interrupt vectors to populate
 * @mask: Bitmask of port capabilities returned by get_port_device_capability()
 *
 * Return value: 0 on success, error code on failure
 */
static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
{
	int nr_entries, nvec, pcie_irq;
	u32 pme = 0, aer = 0, dpc = 0;

	/* Allocate the maximum possible number of MSI/MSI-X vectors */
	nr_entries = pci_alloc_irq_vectors(dev, 1, PCIE_PORT_MAX_MSI_ENTRIES,
			PCI_IRQ_MSIX | PCI_IRQ_MSI);
	if (nr_entries < 0)
		return nr_entries;

	/* See how many and which Interrupt Message Numbers we actually use */
	nvec = pcie_message_numbers(dev, mask, &pme, &aer, &dpc);
	if (nvec > nr_entries) {
		pci_free_irq_vectors(dev);
		return -EIO;
	}

	/*
	 * If we allocated more than we need, free them and reallocate fewer.
	 *
	 * Reallocating may change the specific vectors we get, so
	 * pci_irq_vector() must be done *after* the reallocation.
	 *
	 * If we're using MSI, hardware is *allowed* to change the Interrupt
	 * Message Numbers when we free and reallocate the vectors, but we
	 * assume it won't because we allocate enough vectors for the
	 * biggest Message Number we found.
	 */
	if (nvec != nr_entries) {
		pci_free_irq_vectors(dev);

		nr_entries = pci_alloc_irq_vectors(dev, nvec, nvec,
				PCI_IRQ_MSIX | PCI_IRQ_MSI);
		if (nr_entries < 0)
			return nr_entries;
	}

	/* PME, hotplug and bandwidth notification share an MSI/MSI-X vector */
	if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
		    PCIE_PORT_SERVICE_BWNOTIF)) {
		pcie_irq = pci_irq_vector(dev, pme);
		irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pcie_irq;
		irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pcie_irq;
		irqs[PCIE_PORT_SERVICE_BWNOTIF_SHIFT] = pcie_irq;
	}

	if (mask & PCIE_PORT_SERVICE_AER)
		irqs[PCIE_PORT_SERVICE_AER_SHIFT] = pci_irq_vector(dev, aer);

	if (mask & PCIE_PORT_SERVICE_DPC)
		irqs[PCIE_PORT_SERVICE_DPC_SHIFT] = pci_irq_vector(dev, dpc);

	return 0;
}

/**
 * pcie_init_service_irqs - initialize irqs for PCI Express port services
 * @dev: PCI Express port to handle
 * @irqs: Array of irqs to populate
 * @mask: Bitmask of port capabilities returned by get_port_device_capability()
 *
 * Return value: Interrupt mode associated with the port
 */
static int pcie_init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
{
	int ret, i;

	for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
		irqs[i] = -1;

	/*
	 * If we support PME but can't use MSI/MSI-X for it, we have to
	 * fall back to INTx or other interrupts, e.g., a system shared
	 * interrupt.
	 */
	if ((mask & PCIE_PORT_SERVICE_PME) && pcie_pme_no_msi())
		goto legacy_irq;

	/* Try to use MSI-X or MSI if supported */
	if (pcie_port_enable_irq_vec(dev, irqs, mask) == 0)
		return 0;

legacy_irq:
	/* fall back to legacy IRQ */
	ret = pci_alloc_irq_vectors(dev, 1, 1, PCI_IRQ_LEGACY);
	if (ret < 0)
		return -ENODEV;

	for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
		irqs[i] = pci_irq_vector(dev, 0);

	return 0;
}

/**
 * get_port_device_capability - discover capabilities of a PCI Express port
 * @dev: PCI Express port to examine
 *
 * The capabilities are read from the port's PCI Express configuration registers
 * as described in PCI Express Base Specification 1.0a sections 7.8.2, 7.8.9 and
 * 7.9 - 7.11.
 *
 * Return value: Bitmask of discovered port capabilities
 */
static int get_port_device_capability(struct pci_dev *dev)
{
	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
	int services = 0;

	if (dev->is_hotplug_bridge &&
	    (pcie_ports_native || host->native_pcie_hotplug)) {
		services |= PCIE_PORT_SERVICE_HP;

		/*
		 * Disable hot-plug interrupts in case they have been enabled
		 * by the BIOS and the hot-plug service driver is not loaded.
		 */
		pcie_capability_clear_word(dev, PCI_EXP_SLTCTL,
			  PCI_EXP_SLTCTL_CCIE | PCI_EXP_SLTCTL_HPIE);
	}

#ifdef CONFIG_PCIEAER
	if (dev->aer_cap && pci_aer_available() &&
	    (pcie_ports_native || host->native_aer)) {
		services |= PCIE_PORT_SERVICE_AER;

		/*
		 * Disable AER on this port in case it's been enabled by the
		 * BIOS (the AER service driver will enable it when necessary).
		 */
		pci_disable_pcie_error_reporting(dev);
	}
#endif

	/*
	 * Root ports are capable of generating PME too.  Root Complex
	 * Event Collectors can also generate PMEs, but we don't handle
	 * those yet.
	 */
	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT &&
	    (pcie_ports_native || host->native_pme)) {
		services |= PCIE_PORT_SERVICE_PME;

		/*
		 * Disable PME interrupt on this port in case it's been enabled
		 * by the BIOS (the PME service driver will enable it when
		 * necessary).
		 */
		pcie_pme_interrupt_enable(dev, false);
	}

	if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
	    pci_aer_available() && services & PCIE_PORT_SERVICE_AER)
		services |= PCIE_PORT_SERVICE_DPC;

	if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
	    pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
		services |= PCIE_PORT_SERVICE_BWNOTIF;

	return services;
}

/**
 * pcie_device_init - allocate and initialize PCI Express port service device
 * @pdev: PCI Express port to associate the service device with
 * @service: Type of service to associate with the service device
 * @irq: Interrupt vector to associate with the service device
 */
static int pcie_device_init(struct pci_dev *pdev, int service, int irq)
{
	int retval;
	struct pcie_device *pcie;
	struct device *device;

	pcie = kzalloc(sizeof(*pcie), GFP_KERNEL);
	if (!pcie)
		return -ENOMEM;
	pcie->port = pdev;
	pcie->irq = irq;
	pcie->service = service;

	/* Initialize generic device interface */
	device = &pcie->device;
	device->bus = &pcie_port_bus_type;
	device->release = release_pcie_device;	/* callback to free pcie dev */
	dev_set_name(device, "%s:pcie%03x",
		     pci_name(pdev),
		     get_descriptor_id(pci_pcie_type(pdev), service));
	device->parent = &pdev->dev;
	device_enable_async_suspend(device);

	retval = device_register(device);
	if (retval) {
		put_device(device);
		return retval;
	}

	pm_runtime_no_callbacks(device);

	return 0;
}

/**
 * pcie_port_device_register - register PCI Express port
 * @dev: PCI Express port to register
 *
 * Allocate the port extension structure and register services associated with
 * the port.
 */
int pcie_port_device_register(struct pci_dev *dev)
{
	int status, capabilities, i, nr_service;
	int irqs[PCIE_PORT_DEVICE_MAXSERVICES];

	/* Enable PCI Express port device */
	status = pci_enable_device(dev);
	if (status)
		return status;

	/* Get and check PCI Express port services */
	capabilities = get_port_device_capability(dev);
	if (!capabilities)
		return 0;

	pci_set_master(dev);
	/*
	 * Initialize service irqs. Don't use service devices that
	 * require interrupts if there is no way to generate them.
	 * However, some drivers may have a polling mode (e.g. pciehp_poll_mode)
	 * that can be used in the absence of irqs.  Allow them to determine
	 * if that is to be used.
	 */
	status = pcie_init_service_irqs(dev, irqs, capabilities);
	if (status) {
		capabilities &= PCIE_PORT_SERVICE_HP;
		if (!capabilities)
			goto error_disable;
	}

	/* Allocate child services if any */
	status = -ENODEV;
	nr_service = 0;
	for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++) {
		int service = 1 << i;
		if (!(capabilities & service))
			continue;
		if (!pcie_device_init(dev, service, irqs[i]))
			nr_service++;
	}
	if (!nr_service)
		goto error_cleanup_irqs;

	return 0;

error_cleanup_irqs:
	pci_free_irq_vectors(dev);
error_disable:
	pci_disable_device(dev);
	return status;
}

#ifdef CONFIG_PM
typedef int (*pcie_pm_callback_t)(struct pcie_device *);

static int pm_iter(struct device *dev, void *data)
{
	struct pcie_port_service_driver *service_driver;
	size_t offset = *(size_t *)data;
	pcie_pm_callback_t cb;

	if ((dev->bus == &pcie_port_bus_type) && dev->driver) {
		service_driver = to_service_driver(dev->driver);
		cb = *(pcie_pm_callback_t *)((void *)service_driver + offset);
		if (cb)
			return cb(to_pcie_device(dev));
	}
	return 0;
}

static int get_downstream_delay(struct pci_bus *bus)
{
	struct pci_dev *pdev;
	int min_delay = 100;
	int max_delay = 0;

	list_for_each_entry(pdev, &bus->devices, bus_list) {
		if (!pdev->imm_ready)
			min_delay = 0;
		else if (pdev->d3cold_delay < min_delay)
			min_delay = pdev->d3cold_delay;
		if (pdev->d3cold_delay > max_delay)
			max_delay = pdev->d3cold_delay;
	}

	return max(min_delay, max_delay);
}

/*
 * wait_for_downstream_link - Wait for downstream link to establish
 * @pdev: PCIe port whose downstream link is waited
 *
 * Handle delays according to PCIe 4.0 section 6.6.1 before configuration
 * access to the downstream component is permitted.
 *
 * This blocks PCI core resume of the hierarchy below this port until the
 * link is trained. Should be called before resuming port services to
 * prevent pciehp from starting to tear-down the hierarchy too soon.
 */
static void wait_for_downstream_link(struct pci_dev *pdev)
{
	int delay;

	if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT &&
	    pci_pcie_type(pdev) != PCI_EXP_TYPE_DOWNSTREAM)
		return;

	if (pci_dev_is_disconnected(pdev))
		return;

	if (!pdev->subordinate || list_empty(&pdev->subordinate->devices) ||
	    !pdev->bridge_d3)
		return;

	delay = get_downstream_delay(pdev->subordinate);
	if (!delay)
		return;

	dev_dbg(&pdev->dev, "waiting downstream link for %d ms\n", delay);

	/*
	 * If downstream port does not support speeds greater than 5 GT/s
	 * need to wait 100ms. For higher speeds (gen3) we need to wait
	 * first for the data link layer to become active.
	 */
	if (pcie_get_speed_cap(pdev) <= PCIE_SPEED_5_0GT)
		msleep(delay);
	else
		pcie_wait_for_link_delay(pdev, true, delay);
}

/**
 * pcie_port_device_suspend - suspend port services associated with a PCIe port
 * @dev: PCI Express port to handle
 */
int pcie_port_device_suspend(struct device *dev)
{
	size_t off = offsetof(struct pcie_port_service_driver, suspend);
	return device_for_each_child(dev, &off, pm_iter);
}

int pcie_port_device_resume_noirq(struct device *dev)
{
	size_t off = offsetof(struct pcie_port_service_driver, resume_noirq);

	wait_for_downstream_link(to_pci_dev(dev));
	return device_for_each_child(dev, &off, pm_iter);
}

/**
 * pcie_port_device_resume - resume port services associated with a PCIe port
 * @dev: PCI Express port to handle
 */
int pcie_port_device_resume(struct device *dev)
{
	size_t off = offsetof(struct pcie_port_service_driver, resume);
	return device_for_each_child(dev, &off, pm_iter);
}

/**
 * pcie_port_device_runtime_suspend - runtime suspend port services
 * @dev: PCI Express port to handle
 */
int pcie_port_device_runtime_suspend(struct device *dev)
{
	size_t off = offsetof(struct pcie_port_service_driver, runtime_suspend);
	return device_for_each_child(dev, &off, pm_iter);
}

/**
 * pcie_port_device_runtime_resume - runtime resume port services
 * @dev: PCI Express port to handle
 */
int pcie_port_device_runtime_resume(struct device *dev)
{
	size_t off = offsetof(struct pcie_port_service_driver, runtime_resume);

	wait_for_downstream_link(to_pci_dev(dev));
	return device_for_each_child(dev, &off, pm_iter);
}
#endif /* PM */

static int remove_iter(struct device *dev, void *data)
{
	if (dev->bus == &pcie_port_bus_type)
		device_unregister(dev);
	return 0;
}

static int find_service_iter(struct device *device, void *data)
{
	struct pcie_port_service_driver *service_driver;
	struct portdrv_service_data *pdrvs;
	u32 service;

	pdrvs = (struct portdrv_service_data *) data;
	service = pdrvs->service;

	if (device->bus == &pcie_port_bus_type && device->driver) {
		service_driver = to_service_driver(device->driver);
		if (service_driver->service == service) {
			pdrvs->drv = service_driver;
			pdrvs->dev = device;
			return 1;
		}
	}

	return 0;
}

/**
 * pcie_port_find_service - find the service driver
 * @dev: PCI Express port the service is associated with
 * @service: Service to find
 *
 * Find PCI Express port service driver associated with given service
 */
struct pcie_port_service_driver *pcie_port_find_service(struct pci_dev *dev,
							u32 service)
{
	struct pcie_port_service_driver *drv;
	struct portdrv_service_data pdrvs;

	pdrvs.drv = NULL;
	pdrvs.service = service;
	device_for_each_child(&dev->dev, &pdrvs, find_service_iter);

	drv = pdrvs.drv;
	return drv;
}

/**
 * pcie_port_find_device - find the struct device
 * @dev: PCI Express port the service is associated with
 * @service: For the service to find
 *
 * Find the struct device associated with given service on a pci_dev
 */
struct device *pcie_port_find_device(struct pci_dev *dev,
				      u32 service)
{
	struct device *device;
	struct portdrv_service_data pdrvs;

	pdrvs.dev = NULL;
	pdrvs.service = service;
	device_for_each_child(&dev->dev, &pdrvs, find_service_iter);

	device = pdrvs.dev;
	return device;
}
EXPORT_SYMBOL_GPL(pcie_port_find_device);

/**
 * pcie_port_device_remove - unregister PCI Express port service devices
 * @dev: PCI Express port the service devices to unregister are associated with
 *
 * Remove PCI Express port service devices associated with given port and
 * disable MSI-X or MSI for the port.
 */
void pcie_port_device_remove(struct pci_dev *dev)
{
	device_for_each_child(&dev->dev, NULL, remove_iter);
	pci_free_irq_vectors(dev);
	pci_disable_device(dev);
}

/**
 * pcie_port_probe_service - probe driver for given PCI Express port service
 * @dev: PCI Express port service device to probe against
 *
 * If PCI Express port service driver is registered with
 * pcie_port_service_register(), this function will be called by the driver core
 * whenever match is found between the driver and a port service device.
 */
static int pcie_port_probe_service(struct device *dev)
{
	struct pcie_device *pciedev;
	struct pcie_port_service_driver *driver;
	int status;

	if (!dev || !dev->driver)
		return -ENODEV;

	driver = to_service_driver(dev->driver);
	if (!driver || !driver->probe)
		return -ENODEV;

	pciedev = to_pcie_device(dev);
	status = driver->probe(pciedev);
	if (status)
		return status;

	get_device(dev);
	return 0;
}

/**
 * pcie_port_remove_service - detach driver from given PCI Express port service
 * @dev: PCI Express port service device to handle
 *
 * If PCI Express port service driver is registered with
 * pcie_port_service_register(), this function will be called by the driver core
 * when device_unregister() is called for the port service device associated
 * with the driver.
 */
static int pcie_port_remove_service(struct device *dev)
{
	struct pcie_device *pciedev;
	struct pcie_port_service_driver *driver;

	if (!dev || !dev->driver)
		return 0;

	pciedev = to_pcie_device(dev);
	driver = to_service_driver(dev->driver);
	if (driver && driver->remove) {
		driver->remove(pciedev);
		put_device(dev);
	}
	return 0;
}

/**
 * pcie_port_shutdown_service - shut down given PCI Express port service
 * @dev: PCI Express port service device to handle
 *
 * If PCI Express port service driver is registered with
 * pcie_port_service_register(), this function will be called by the driver core
 * when device_shutdown() is called for the port service device associated
 * with the driver.
 */
static void pcie_port_shutdown_service(struct device *dev) {}

/**
 * pcie_port_service_register - register PCI Express port service driver
 * @new: PCI Express port service driver to register
 */
int pcie_port_service_register(struct pcie_port_service_driver *new)
{
	if (pcie_ports_disabled)
		return -ENODEV;

	new->driver.name = new->name;
	new->driver.bus = &pcie_port_bus_type;
	new->driver.probe = pcie_port_probe_service;
	new->driver.remove = pcie_port_remove_service;
	new->driver.shutdown = pcie_port_shutdown_service;

	return driver_register(&new->driver);
}
EXPORT_SYMBOL(pcie_port_service_register);

/**
 * pcie_port_service_unregister - unregister PCI Express port service driver
 * @drv: PCI Express port service driver to unregister
 */
void pcie_port_service_unregister(struct pcie_port_service_driver *drv)
{
	driver_unregister(&drv->driver);
}
EXPORT_SYMBOL(pcie_port_service_unregister);