path: root/drivers/pci/devres.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/device.h>
#include <linux/pci.h>
#include "pci.h"

/*
 * On the state of PCI's devres implementation:
 *
 * The older devres API for PCI has two significant problems:
 *
 * 1. It is very strongly tied to the statically allocated mapping table in
 *    struct pcim_iomap_devres below. This is mostly solved in the sense of the
 *    pcim_ functions in this file providing things like ranged mapping by
 *    bypassing this table, whereas the functions that were present in the old
 *    API still enter the mapping addresses into the table for users of the old
 *    API.
 *
 * 2. The region-request-functions in pci.c do become managed IF the device has
 *    been enabled with pcim_enable_device() instead of pci_enable_device().
 *    This resulted in the API becoming inconsistent: Some functions have an
 *    obviously managed counter-part (e.g., pci_iomap() <-> pcim_iomap()),
 *    whereas some don't and are never managed, while others don't and are
 *    _sometimes_ managed (e.g. pci_request_region()).
 *
 *    Consequently, in the new API, region requests performed by the pcim_
 *    functions are automatically cleaned up through the devres callback
 *    pcim_addr_resource_release().
 *
 *    Users of pcim_enable_device() + pci_*region*() are redirected in
 *    pci.c to the managed functions here in this file. This isn't exactly
 *    perfect, but the only alternative way would be to port ALL drivers
 *    using said combination to pcim_ functions.
 *
 * TODO:
 * Remove the legacy table entirely once all calls to pcim_iomap_table() in
 * the kernel have been removed.
 */

/*
 * Legacy struct storing addresses to whole mapped BARs.
 */
struct pcim_iomap_devres {
	void __iomem *table[PCI_STD_NUM_BARS];
};

/* Used to restore the old INTx state on driver detach. */
struct pcim_intx_devres {
	int orig_intx;
};

enum pcim_addr_devres_type {
	/* Default initializer. */
	PCIM_ADDR_DEVRES_TYPE_INVALID,

	/* A requested region spanning an entire BAR. */
	PCIM_ADDR_DEVRES_TYPE_REGION,

	/*
	 * A requested region spanning an entire BAR, and a mapping for
	 * the entire BAR.
	 */
	PCIM_ADDR_DEVRES_TYPE_REGION_MAPPING,

	/*
	 * A mapping within a BAR, either spanning the whole BAR or just a
	 * range.  Without a requested region.
	 */
	PCIM_ADDR_DEVRES_TYPE_MAPPING,
};

/*
 * This struct envelops IO or MEM addresses, i.e., mappings and region
 * requests, because those are very frequently requested and released
 * together.
 */
struct pcim_addr_devres {
	enum pcim_addr_devres_type type;
	void __iomem *baseaddr;
	unsigned long offset;
	unsigned long len;
	int bar;
};

static inline void pcim_addr_devres_clear(struct pcim_addr_devres *res)
{
	memset(res, 0, sizeof(*res));
	res->bar = -1;
}

/*
 * The following functions, __pcim_*_region*, exist as counterparts to the
 * versions from pci.c - which, unfortunately, can be in "hybrid mode", i.e.,
 * sometimes managed, sometimes not.
 *
 * To separate the APIs cleanly, we define our own, simplified versions here.
 */

/**
 * __pcim_request_region_range - Request a ranged region
 * @pdev: PCI device the region belongs to
 * @bar: BAR the range is within
 * @offset: offset from the BAR's start address
 * @maxlen: length in bytes, beginning at @offset
 * @name: name associated with the request
 * @req_flags: flags for the request, e.g., for kernel-exclusive requests
 *
 * Returns: 0 on success, a negative error code on failure.
 *
 * Request a range within a device's PCI BAR.  Sanity check the input.
 */
static int __pcim_request_region_range(struct pci_dev *pdev, int bar,
				       unsigned long offset,
				       unsigned long maxlen,
				       const char *name, int req_flags)
{
	resource_size_t start = pci_resource_start(pdev, bar);
	resource_size_t len = pci_resource_len(pdev, bar);
	unsigned long dev_flags = pci_resource_flags(pdev, bar);

	if (start == 0 || len == 0) /* Unused BAR. */
		return 0;
	if (len <= offset)
		return -EINVAL;

	start += offset;
	len -= offset;

	if (len > maxlen && maxlen != 0)
		len = maxlen;

	if (dev_flags & IORESOURCE_IO) {
		if (!request_region(start, len, name))
			return -EBUSY;
	} else if (dev_flags & IORESOURCE_MEM) {
		if (!__request_mem_region(start, len, name, req_flags))
			return -EBUSY;
	} else {
		/* That's not a device we can request anything on. */
		return -ENODEV;
	}

	return 0;
}

static void __pcim_release_region_range(struct pci_dev *pdev, int bar,
					unsigned long offset,
					unsigned long maxlen)
{
	resource_size_t start = pci_resource_start(pdev, bar);
	resource_size_t len = pci_resource_len(pdev, bar);
	unsigned long flags = pci_resource_flags(pdev, bar);

	if (len <= offset || start == 0)
		return;

	if (len == 0 || maxlen == 0) /* This an unused BAR. Do nothing. */
		return;

	start += offset;
	len -= offset;

	if (len > maxlen)
		len = maxlen;

	if (flags & IORESOURCE_IO)
		release_region(start, len);
	else if (flags & IORESOURCE_MEM)
		release_mem_region(start, len);
}

static int __pcim_request_region(struct pci_dev *pdev, int bar,
				 const char *