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linux-next/drivers/pci/access.c
Maciej W. Rozycki 503fa23614 PCI: Access Link 2 registers only for devices with Links 
PCIe r2.0, sec 7.8 added Link Capabilities/Status/Control 2 registers to
the PCIe Capability with Capability Version 2.

Previously we assumed these registers were implemented for all PCIe
Capabilities of version 2 or greater, but in fact they are only
implemented for devices with Links.

Update pcie_capability_reg_implemented() to check whether the device has
a Link.

[bhelgaas: commit log, squash export]
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209100057070.2275@angie.orcam.me.uk
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209100057300.2275@angie.orcam.me.uk
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2022-11-04 10:38:11 -05:00

589 lines
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// SPDX-License-Identifier: GPL-2.0
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/wait.h>
#include "pci.h"
/*
* This interrupt-safe spinlock protects all accesses to PCI
* configuration space.
*/
DEFINE_RAW_SPINLOCK(pci_lock);
/*
* Wrappers for all PCI configuration access functions. They just check
* alignment, do locking and call the low-level functions pointed to
* by pci_dev->ops.
*/
#define PCI_byte_BAD 0
#define PCI_word_BAD (pos & 1)
#define PCI_dword_BAD (pos & 3)
#ifdef CONFIG_PCI_LOCKLESS_CONFIG
# define pci_lock_config(f) do { (void)(f); } while (0)
# define pci_unlock_config(f) do { (void)(f); } while (0)
#else
# define pci_lock_config(f) raw_spin_lock_irqsave(&pci_lock, f)
# define pci_unlock_config(f) raw_spin_unlock_irqrestore(&pci_lock, f)
#endif
#define PCI_OP_READ(size, type, len) \
int noinline pci_bus_read_config_##size \
(struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
{ \
int res; \
unsigned long flags; \
u32 data = 0; \
if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
pci_lock_config(flags); \
res = bus->ops->read(bus, devfn, pos, len, &data); \
if (res) \
PCI_SET_ERROR_RESPONSE(value); \
else \
*value = (type)data; \
pci_unlock_config(flags); \
return res; \
}
#define PCI_OP_WRITE(size, type, len) \
int noinline pci_bus_write_config_##size \
(struct pci_bus *bus, unsigned int devfn, int pos, type value) \
{ \
int res; \
unsigned long flags; \
if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
pci_lock_config(flags); \
res = bus->ops->write(bus, devfn, pos, len, value); \
pci_unlock_config(flags); \
return res; \
}
PCI_OP_READ(byte, u8, 1)
PCI_OP_READ(word, u16, 2)
PCI_OP_READ(dword, u32, 4)
PCI_OP_WRITE(byte, u8, 1)
PCI_OP_WRITE(word, u16, 2)
PCI_OP_WRITE(dword, u32, 4)
EXPORT_SYMBOL(pci_bus_read_config_byte);
EXPORT_SYMBOL(pci_bus_read_config_word);
EXPORT_SYMBOL(pci_bus_read_config_dword);
EXPORT_SYMBOL(pci_bus_write_config_byte);
EXPORT_SYMBOL(pci_bus_write_config_word);
EXPORT_SYMBOL(pci_bus_write_config_dword);
int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn,
int where, int size, u32 *val)
{
void __iomem *addr;
addr = bus->ops->map_bus(bus, devfn, where);
if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
if (size == 1)
*val = readb(addr);
else if (size == 2)
*val = readw(addr);
else
*val = readl(addr);
return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_read);
int pci_generic_config_write(struct pci_bus *bus, unsigned int devfn,
int where, int size, u32 val)
{
void __iomem *addr;
addr = bus->ops->map_bus(bus, devfn, where);
if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
if (size == 1)
writeb(val, addr);
else if (size == 2)
writew(val, addr);
else
writel(val, addr);
return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_write);
int pci_generic_config_read32(struct pci_bus *bus, unsigned int devfn,
int where, int size, u32 *val)
{
void __iomem *addr;
addr = bus->ops->map_bus(bus, devfn, where & ~0x3);
if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
*val = readl(addr);
if (size <= 2)
*val = (*val >> (8 * (where & 3))) & ((1 << (size * 8)) - 1);
return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_read32);
int pci_generic_config_write32(struct pci_bus *bus, unsigned int devfn,
int where, int size, u32 val)
{
void __iomem *addr;
u32 mask, tmp;
addr = bus->ops->map_bus(bus, devfn, where & ~0x3);
if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
if (size == 4) {
writel(val, addr);
return PCIBIOS_SUCCESSFUL;
}
/*
* In general, hardware that supports only 32-bit writes on PCI is
* not spec-compliant. For example, software may perform a 16-bit
* write. If the hardware only supports 32-bit accesses, we must
* do a 32-bit read, merge in the 16 bits we intend to write,
* followed by a 32-bit write. If the 16 bits we *don't* intend to
* write happen to have any RW1C (write-one-to-clear) bits set, we
* just inadvertently cleared something we shouldn't have.
*/
if (!bus->unsafe_warn) {
dev_warn(&bus->dev, "%d-byte config write to %04x:%02x:%02x.%d offset %#x may corrupt adjacent RW1C bits\n",
size, pci_domain_nr(bus), bus->number,
PCI_SLOT(devfn), PCI_FUNC(devfn), where);
bus->unsafe_warn = 1;
}
mask = ~(((1 << (size * 8)) - 1) << ((where & 0x3) * 8));
tmp = readl(addr) & mask;
tmp |= val << ((where & 0x3) * 8);
writel(tmp, addr);
return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_write32);
/**
* pci_bus_set_ops - Set raw operations of pci bus
* @bus: pci bus struct
* @ops: new raw operations
*
* Return previous raw operations
*/
struct pci_ops *pci_bus_set_ops(struct pci_bus *bus, struct pci_ops *ops)
{
struct pci_ops *old_ops;
unsigned long flags;
raw_spin_lock_irqsave(&pci_lock, flags);
old_ops = bus->ops;
bus->ops = ops;
raw_spin_unlock_irqrestore(&pci_lock, flags);
return old_ops;
}
EXPORT_SYMBOL(pci_bus_set_ops);
/*
* The following routines are to prevent the user from accessing PCI config
* space when it's unsafe to do so. Some devices require this during BIST and
* we're required to prevent it during D-state transitions.
*
* We have a bit per device to indicate it's blocked and a global wait queue
* for callers to sleep on until devices are unblocked.
*/
static DECLARE_WAIT_QUEUE_HEAD(pci_cfg_wait);
static noinline void pci_wait_cfg(struct pci_dev *dev)
__must_hold(&pci_lock)
{
do {
raw_spin_unlock_irq(&pci_lock);
wait_event(pci_cfg_wait, !dev->block_cfg_access);
raw_spin_lock_irq(&pci_lock);
} while (dev->block_cfg_access);
}
/* Returns 0 on success, negative values indicate error. */
#define PCI_USER_READ_CONFIG(size, type) \
int pci_user_read_config_##size \
(struct pci_dev *dev, int pos, type *val) \
{ \
int ret = PCIBIOS_SUCCESSFUL; \
u32 data = -1; \
if (PCI_##size##_BAD) \
return -EINVAL; \
raw_spin_lock_irq(&pci_lock); \
if (unlikely(dev->block_cfg_access)) \
pci_wait_cfg(dev); \
ret = dev->bus->ops->read(dev->bus, dev->devfn, \
pos, sizeof(type), &data); \
raw_spin_unlock_irq(&pci_lock); \
if (ret) \
PCI_SET_ERROR_RESPONSE(val); \
else \
*val = (type)data; \
return pcibios_err_to_errno(ret); \
} \
EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
/* Returns 0 on success, negative values indicate error. */
#define PCI_USER_WRITE_CONFIG(size, type) \
int pci_user_write_config_##size \
(struct pci_dev *dev, int pos, type val) \
{ \
int ret = PCIBIOS_SUCCESSFUL; \
if (PCI_##size##_BAD) \
return -EINVAL; \
raw_spin_lock_irq(&pci_lock); \
if (unlikely(dev->block_cfg_access)) \
pci_wait_cfg(dev); \
ret = dev->bus->ops->write(dev->bus, dev->devfn, \
pos, sizeof(type), val); \
raw_spin_unlock_irq(&pci_lock); \
return pcibios_err_to_errno(ret); \
} \
EXPORT_SYMBOL_GPL(pci_user_write_config_##size);
PCI_USER_READ_CONFIG(byte, u8)
PCI_USER_READ_CONFIG(word, u16)
PCI_USER_READ_CONFIG(dword, u32)
PCI_USER_WRITE_CONFIG(byte, u8)
PCI_USER_WRITE_CONFIG(word, u16)
PCI_USER_WRITE_CONFIG(dword, u32)
/**
* pci_cfg_access_lock - Lock PCI config reads/writes
* @dev: pci device struct
*
* When access is locked, any userspace reads or writes to config
* space and concurrent lock requests will sleep until access is
* allowed via pci_cfg_access_unlock() again.
*/
void pci_cfg_access_lock(struct pci_dev *dev)
{
might_sleep();
raw_spin_lock_irq(&pci_lock);
if (dev->block_cfg_access)
pci_wait_cfg(dev);
dev->block_cfg_access = 1;
raw_spin_unlock_irq(&pci_lock);
}
EXPORT_SYMBOL_GPL(pci_cfg_access_lock);
/**
* pci_cfg_access_trylock - try to lock PCI config reads/writes
* @dev: pci device struct
*
* Same as pci_cfg_access_lock, but will return 0 if access is
* already locked, 1 otherwise. This function can be used from
* atomic contexts.
*/
bool pci_cfg_access_trylock(struct pci_dev *dev)
{
unsigned long flags;
bool locked = true;
raw_spin_lock_irqsave(&pci_lock, flags);
if (dev->block_cfg_access)
locked = false;
else
dev->block_cfg_access = 1;
raw_spin_unlock_irqrestore(&pci_lock, flags);
return locked;
}
EXPORT_SYMBOL_GPL(pci_cfg_access_trylock);
/**
* pci_cfg_access_unlock - Unlock PCI config reads/writes
* @dev: pci device struct
*
* This function allows PCI config accesses to resume.
*/
void pci_cfg_access_unlock(struct pci_dev *dev)
{
unsigned long flags;
raw_spin_lock_irqsave(&pci_lock, flags);
/*
* This indicates a problem in the caller, but we don't need
* to kill them, unlike a double-block above.
*/
WARN_ON(!dev->block_cfg_access);
dev->block_cfg_access = 0;
raw_spin_unlock_irqrestore(&pci_lock, flags);
wake_up_all(&pci_cfg_wait);
}
EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);
static inline int pcie_cap_version(const struct pci_dev *dev)
{
return pcie_caps_reg(dev) & PCI_EXP_FLAGS_VERS;
}
bool pcie_cap_has_lnkctl(const struct pci_dev *dev)
{
int type = pci_pcie_type(dev);
return type == PCI_EXP_TYPE_ENDPOINT ||
type == PCI_EXP_TYPE_LEG_END ||
type == PCI_EXP_TYPE_ROOT_PORT ||
type == PCI_EXP_TYPE_UPSTREAM ||
type == PCI_EXP_TYPE_DOWNSTREAM ||
type == PCI_EXP_TYPE_PCI_BRIDGE ||
type == PCI_EXP_TYPE_PCIE_BRIDGE;
}
bool pcie_cap_has_lnkctl2(const struct pci_dev *dev)
{
return pcie_cap_has_lnkctl(dev) && pcie_cap_version(dev) > 1;
}
static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev)
{
return pcie_downstream_port(dev) &&
pcie_caps_reg(dev) & PCI_EXP_FLAGS_SLOT;
}
bool pcie_cap_has_rtctl(const struct pci_dev *dev)
{
int type = pci_pcie_type(dev);
return type == PCI_EXP_TYPE_ROOT_PORT ||
type == PCI_EXP_TYPE_RC_EC;
}
static bool pcie_capability_reg_implemented(struct pci_dev *dev, int pos)
{
if (!pci_is_pcie(dev))
return false;
switch (pos) {
case PCI_EXP_FLAGS:
return true;
case PCI_EXP_DEVCAP:
case PCI_EXP_DEVCTL:
case PCI_EXP_DEVSTA:
return true;
case PCI_EXP_LNKCAP:
case PCI_EXP_LNKCTL:
case PCI_EXP_LNKSTA:
return pcie_cap_has_lnkctl(dev);
case PCI_EXP_SLTCAP:
case PCI_EXP_SLTCTL:
case PCI_EXP_SLTSTA:
return pcie_cap_has_sltctl(dev);
case PCI_EXP_RTCTL:
case PCI_EXP_RTCAP:
case PCI_EXP_RTSTA:
return pcie_cap_has_rtctl(dev);
case PCI_EXP_DEVCAP2:
case PCI_EXP_DEVCTL2:
return pcie_cap_version(dev) > 1;
case PCI_EXP_LNKCAP2:
case PCI_EXP_LNKCTL2:
case PCI_EXP_LNKSTA2:
return pcie_cap_has_lnkctl2(dev);
default:
return false;
}
}
/*
* Note that these accessor functions are only for the "PCI Express
* Capability" (see PCIe spec r3.0, sec 7.8). They do not apply to the
* other "PCI Express Extended Capabilities" (AER, VC, ACS, MFVC, etc.)
*/
int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val)
{
int ret;
*val = 0;
if (pos & 1)
return PCIBIOS_BAD_REGISTER_NUMBER;
if (pcie_capability_reg_implemented(dev, pos)) {
ret = pci_read_config_word(dev, pci_pcie_cap(dev) + pos, val);
/*
* Reset *val to 0 if pci_read_config_word() fails; it may
* have been written as 0xFFFF (PCI_ERROR_RESPONSE) if the
* config read failed on PCI.
*/
if (ret)
*val = 0;
return ret;
}
/*
* For Functions that do not implement the Slot Capabilities,
* Slot Status, and Slot Control registers, these spaces must
* be hardwired to 0b, with the exception of the Presence Detect
* State bit in the Slot Status register of Downstream Ports,
* which must be hardwired to 1b. (PCIe Base Spec 3.0, sec 7.8)
*/
if (pci_is_pcie(dev) && pcie_downstream_port(dev) &&
pos == PCI_EXP_SLTSTA)
*val = PCI_EXP_SLTSTA_PDS;
return 0;
}
EXPORT_SYMBOL(pcie_capability_read_word);
int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val)
{
int ret;
*val = 0;
if (pos & 3)
return PCIBIOS_BAD_REGISTER_NUMBER;
if (pcie_capability_reg_implemented(dev, pos)) {
ret = pci_read_config_dword(dev, pci_pcie_cap(dev) + pos, val);
/*
* Reset *val to 0 if pci_read_config_dword() fails; it may
* have been written as 0xFFFFFFFF (PCI_ERROR_RESPONSE) if
* the config read failed on PCI.
*/
if (ret)
*val = 0;
return ret;
}
if (pci_is_pcie(dev) && pcie_downstream_port(dev) &&
pos == PCI_EXP_SLTSTA)
*val = PCI_EXP_SLTSTA_PDS;
return 0;
}
EXPORT_SYMBOL(pcie_capability_read_dword);
int pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val)
{
if (pos & 1)
return PCIBIOS_BAD_REGISTER_NUMBER;
if (!pcie_capability_reg_implemented(dev, pos))
return 0;
return pci_write_config_word(dev, pci_pcie_cap(dev) + pos, val);
}
EXPORT_SYMBOL(pcie_capability_write_word);
int pcie_capability_write_dword(struct pci_dev *dev, int pos, u32 val)
{
if (pos & 3)
return PCIBIOS_BAD_REGISTER_NUMBER;
if (!pcie_capability_reg_implemented(dev, pos))
return 0;
return pci_write_config_dword(dev, pci_pcie_cap(dev) + pos, val);
}
EXPORT_SYMBOL(pcie_capability_write_dword);
int pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos,
u16 clear, u16 set)
{
int ret;
u16 val;
ret = pcie_capability_read_word(dev, pos, &val);
if (!ret) {
val &= ~clear;
val |= set;
ret = pcie_capability_write_word(dev, pos, val);
}
return ret;
}
EXPORT_SYMBOL(pcie_capability_clear_and_set_word);
int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos,
u32 clear, u32 set)
{
int ret;
u32 val;
ret = pcie_capability_read_dword(dev, pos, &val);
if (!ret) {
val &= ~clear;
val |= set;
ret = pcie_capability_write_dword(dev, pos, val);
}
return ret;
}
EXPORT_SYMBOL(pcie_capability_clear_and_set_dword);
int pci_read_config_byte(const struct pci_dev *dev, int where, u8 *val)
{
if (pci_dev_is_disconnected(dev)) {
PCI_SET_ERROR_RESPONSE(val);
return PCIBIOS_DEVICE_NOT_FOUND;
}
return pci_bus_read_config_byte(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_read_config_byte);
int pci_read_config_word(const struct pci_dev *dev, int where, u16 *val)
{
if (pci_dev_is_disconnected(dev)) {
PCI_SET_ERROR_RESPONSE(val);
return PCIBIOS_DEVICE_NOT_FOUND;
}
return pci_bus_read_config_word(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_read_config_word);
int pci_read_config_dword(const struct pci_dev *dev, int where,
u32 *val)
{
if (pci_dev_is_disconnected(dev)) {
PCI_SET_ERROR_RESPONSE(val);
return PCIBIOS_DEVICE_NOT_FOUND;
}
return pci_bus_read_config_dword(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_read_config_dword);
int pci_write_config_byte(const struct pci_dev *dev, int where, u8 val)
{
if (pci_dev_is_disconnected(dev))
return PCIBIOS_DEVICE_NOT_FOUND;
return pci_bus_write_config_byte(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_write_config_byte);
int pci_write_config_word(const struct pci_dev *dev, int where, u16 val)
{
if (pci_dev_is_disconnected(dev))
return PCIBIOS_DEVICE_NOT_FOUND;
return pci_bus_write_config_word(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_write_config_word);
int pci_write_config_dword(const struct pci_dev *dev, int where,
u32 val)
{
if (pci_dev_is_disconnected(dev))
return PCIBIOS_DEVICE_NOT_FOUND;
return pci_bus_write_config_dword(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_write_config_dword);
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