Commit 57bdeef4 authored by Naveen Naidu's avatar Naveen Naidu Committed by Bjorn Helgaas
Browse files

PCI: Add PCI_ERROR_RESPONSE and related definitions 



A config or MMIO read from a PCI device that doesn't exist or doesn't
respond causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

Add a PCI_ERROR_RESPONSE definition for that and use it where appropriate
to make these checks consistent and easier to find.

Also add helper definitions PCI_SET_ERROR_RESPONSE() and
PCI_POSSIBLE_ERROR() to make the code more readable.

Suggested-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/55563bf4dfc5d3fdc96695373c659d099bf175b1.1637243717.git.naveennaidu479@gmail.com


Signed-off-by: default avatarNaveen Naidu <naveennaidu479@gmail.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarPali Rohár <pali@kernel.org>
parent fa55b7dc

include/linux/pci.h

+9 −0
Original line number Diff line number Diff line
@@ -154,6 +154,15 @@ enum pci_interrupt_pin { 
/* The number of legacy PCI INTx interrupts */

#define PCI_NUM_INTX	4



/*

 * Reading from a device that doesn't respond typically returns ~0.  A

 * successful read from a device may also return ~0, so you need additional

 * information to reliably identify errors.

 */

#define PCI_ERROR_RESPONSE		(~0ULL)

#define PCI_SET_ERROR_RESPONSE(val)	(*(val) = ((typeof(*(val))) PCI_ERROR_RESPONSE))

#define PCI_POSSIBLE_ERROR(val)		((val) == ((typeof(val)) PCI_ERROR_RESPONSE))



/*

 * pci_power_t values must match the bits in the Capabilities PME_Support

 * and Control/Status PowerState fields in the Power Management capability.