Re: [PATCH 2/6] PCI: Add PCI_EXP_SLTCAP_*_SHIFT macros

Pali Rohár
2022-02-25T12:26:09Z

On Thursday 24 February 2022 14:28:43 Bjorn Helgaas wrote:
> On Tue, Feb 22, 2022 at 05:31:54PM +0100, Pali Rohár wrote:
> > These macros allows to easily compose and extract Slot Power Limit and
> > Physical Slot Number values from Slot Capability Register.
> >
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > Signed-off-by: Marek Behún <kabel@kernel.org>
> > ---
> > include/uapi/linux/pci_regs.h | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> > index 108f8523fa04..3fc9a4cac630 100644
> > --- a/include/uapi/linux/pci_regs.h
> > +++ b/include/uapi/linux/pci_regs.h
> > @@ -591,10 +591,13 @@
> > #define PCI_EXP_SLTCAP_HPS 0x00000020 /* Hot-Plug Surprise */
> > #define PCI_EXP_SLTCAP_HPC 0x00000040 /* Hot-Plug Capable */
> > #define PCI_EXP_SLTCAP_SPLV 0x00007f80 /* Slot Power Limit Value */
> > +#define PCI_EXP_SLTCAP_SPLV_SHIFT 7 /* Slot Power Limit Value shift */
>
> Is there a way to use FIELD_PREP() and FIELD_GET() instead? It seems
> like that's what the cool kids are doing now.

This is possible too.

I have proposed a patch with _SHIFT macros as this is the way how are
other macros in this file defined and used.

> At first I didn't really like them, but they do remove the need for
> adding _SHIFT macros that have to be manually related to the other.
>
> > #define PCI_EXP_SLTCAP_SPLS 0x00018000 /* Slot Power Limit Scale */
> > +#define PCI_EXP_SLTCAP_SPLS_SHIFT 15 /* Slot Power Limit Scale shift */
> > #define PCI_EXP_SLTCAP_EIP 0x00020000 /* Electromechanical Interlock Present */
> > #define PCI_EXP_SLTCAP_NCCS 0x00040000 /* No Command Completed Support */
> > #define PCI_EXP_SLTCAP_PSN 0xfff80000 /* Physical Slot Number */
> > +#define PCI_EXP_SLTCAP_PSN_SHIFT 19 /* Physical Slot Number shift */
> > #define PCI_EXP_SLTCTL 0x18 /* Slot Control */
> > #define PCI_EXP_SLTCTL_ABPE 0x0001 /* Attention Button Pressed Enable */
> > #define PCI_EXP_SLTCTL_PFDE 0x0002 /* Power Fault Detected Enable */
> > --
> > 2.20.1
> >