diff options
Diffstat (limited to 'drivers/pci/pci.c')
| -rw-r--r-- | drivers/pci/pci.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index c3cca7cdc6e5..924193ef4fe1 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2768,6 +2768,116 @@ pci_intx(struct pci_dev *pdev, int enable) } /** + * pci_intx_mask_supported - probe for INTx masking support + * @pdev: the PCI device to operate on + * + * Check if the device dev support INTx masking via the config space + * command word. + */ +bool pci_intx_mask_supported(struct pci_dev *dev) +{ + bool mask_supported = false; + u16 orig, new; + + pci_cfg_access_lock(dev); + + pci_read_config_word(dev, PCI_COMMAND, &orig); + pci_write_config_word(dev, PCI_COMMAND, + orig ^ PCI_COMMAND_INTX_DISABLE); + pci_read_config_word(dev, PCI_COMMAND, &new); + + /* + * There's no way to protect against hardware bugs or detect them + * reliably, but as long as we know what the value should be, let's + * go ahead and check it. + */ + if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) { + dev_err(&dev->dev, "Command register changed from " + "0x%x to 0x%x: driver or hardware bug?\n", orig, new); + } else if ((new ^ orig) & PCI_COMMAND_INTX_DISABLE) { + mask_supported = true; + pci_write_config_word(dev, PCI_COMMAND, orig); + } + + pci_cfg_access_unlock(dev); + return mask_supported; +} +EXPORT_SYMBOL_GPL(pci_intx_mask_supported); + +static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask) +{ + struct pci_bus *bus = dev->bus; + bool mask_updated = true; + u32 cmd_status_dword; + u16 origcmd, newcmd; + unsigned long flags; + bool irq_pending; + + /* + * We do a single dword read to retrieve both command and status. + * Document assumptions that make this possible. + */ + BUILD_BUG_ON(PCI_COMMAND % 4); + BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS); + + raw_spin_lock_irqsave(&pci_lock, flags); + + bus->ops->read(bus, dev->devfn, PCI_COMMAND, 4, &cmd_status_dword); + + irq_pending = (cmd_status_dword >> 16) & PCI_STATUS_INTERRUPT; + + /* + * Check interrupt status register to see whether our device + * triggered the interrupt (when masking) or the next IRQ is + * already pending (when unmasking). + */ + if (mask != irq_pending) { + mask_updated = false; + goto done; + } + + origcmd = cmd_status_dword; + newcmd = origcmd & ~PCI_COMMAND_INTX_DISABLE; + if (mask) + newcmd |= PCI_COMMAND_INTX_DISABLE; + if (newcmd != origcmd) + bus->ops->write(bus, dev->devfn, PCI_COMMAND, 2, newcmd); + +done: + raw_spin_unlock_irqrestore(&pci_lock, flags); + + return mask_updated; +} + +/** + * pci_check_and_mask_intx - mask INTx on pending interrupt + * @pdev: the PCI device to operate on + * + * Check if the device dev has its INTx line asserted, mask it and + * return true in that case. False is returned if not interrupt was + * pending. + */ +bool pci_check_and_mask_intx(struct pci_dev *dev) +{ + return pci_check_and_set_intx_mask(dev, true); +} +EXPORT_SYMBOL_GPL(pci_check_and_mask_intx); + +/** + * pci_check_and_mask_intx - unmask INTx of no interrupt is pending + * @pdev: the PCI device to operate on + * + * Check if the device dev has its INTx line asserted, unmask it if not + * and return true. False is returned and the mask remains active if + * there was still an interrupt pending. + */ +bool pci_check_and_unmask_intx(struct pci_dev *dev) +{ + return pci_check_and_set_intx_mask(dev, false); +} +EXPORT_SYMBOL_GPL(pci_check_and_unmask_intx); + +/** * pci_msi_off - disables any msi or msix capabilities * @dev: the PCI device to operate on * |