From 2253d648f11e844d2dcf572b3bb961e1a7a2b00b Mon Sep 17 00:00:00 2001 From: Stefan Roese Date: Mon, 11 Feb 2019 08:43:25 +0100 Subject: pci: Add comment to mention difference in DEVFN usage in U-Boot vs Linux This patch adds a comment to the header with the PCI_foo macros related to DEVFN to explain the difference in U-Boot vs Linux. Signed-off-by: Stefan Roese Cc: Simon Glass Cc: Bin Meng Reviewed-by: Simon Glass --- include/pci.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/pci.h b/include/pci.h index 936cfe975c..5fb212cab1 100644 --- a/include/pci.h +++ b/include/pci.h @@ -499,9 +499,20 @@ static inline void pci_set_region(struct pci_region *reg, typedef int pci_dev_t; #define PCI_BUS(d) (((d) >> 16) & 0xff) + +/* + * Please note the difference in DEVFN usage in U-Boot vs Linux. U-Boot + * uses DEVFN in bits 15-8 but Linux instead expects DEVFN in bits 7-0. + * Please see the Linux header include/uapi/linux/pci.h for more details. + * This is relevant for the following macros: + * PCI_DEV, PCI_FUNC, PCI_DEVFN + * The U-Boot macro PCI_DEV is equivalent to the Linux PCI_SLOT version with + * the remark from above (input d in bits 15-8 instead of 7-0. + */ #define PCI_DEV(d) (((d) >> 11) & 0x1f) #define PCI_FUNC(d) (((d) >> 8) & 0x7) #define PCI_DEVFN(d, f) ((d) << 11 | (f) << 8) + #define PCI_MASK_BUS(bdf) ((bdf) & 0xffff) #define PCI_ADD_BUS(bus, devfn) (((bus) << 16) | (devfn)) #define PCI_BDF(b, d, f) ((b) << 16 | PCI_DEVFN(d, f)) -- cgit v1.2.1