Re: [PATCH 05/10] PCI/ATS: Use FIELD_GET()

Ilpo Järvinen
2023-10-11T11:29:11Z

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On Tue, 10 Oct 2023, Bjorn Helgaas wrote:

> From: Bjorn Helgaas <bhelgaas@google.com>
>
> Use FIELD_GET() to remove dependences on the field position, i.e., the
> shift value. No functional change intended.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pci/ats.c | 7 ++-----
> include/uapi/linux/pci_regs.h | 1 +
> 2 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index f9cc2e10b676..c570892b2090 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -9,6 +9,7 @@
> * Copyright (C) 2011 Advanced Micro Devices,
> */
>
> +#include <linux/bitfield.h>
> #include <linux/export.h>
> #include <linux/pci-ats.h>
> #include <linux/pci.h>
> @@ -480,8 +481,6 @@ int pci_pasid_features(struct pci_dev *pdev)
> }
> EXPORT_SYMBOL_GPL(pci_pasid_features);
>
> -#define PASID_NUMBER_SHIFT 8
> -#define PASID_NUMBER_MASK (0x1f << PASID_NUMBER_SHIFT)
> /**
> * pci_max_pasids - Get maximum number of PASIDs supported by device
> * @pdev: PCI device structure
> @@ -503,9 +502,7 @@ int pci_max_pasids(struct pci_dev *pdev)
>
> pci_read_config_word(pdev, pasid + PCI_PASID_CAP, &supported);
>
> - supported = (supported & PASID_NUMBER_MASK) >> PASID_NUMBER_SHIFT;
> -
> - return (1 << supported);
> + return (1 << FIELD_GET(PCI_PASID_CAP_WIDTH, supported));
> }
> EXPORT_SYMBOL_GPL(pci_max_pasids);
> #endif /* CONFIG_PCI_PASID */
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 6af1f8d53e97..833e5fb40ea5 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -932,6 +932,7 @@
> #define PCI_PASID_CAP 0x04 /* PASID feature register */
> #define PCI_PASID_CAP_EXEC 0x0002 /* Exec permissions Supported */
> #define PCI_PASID_CAP_PRIV 0x0004 /* Privilege Mode Supported */
> +#define PCI_PASID_CAP_WIDTH 0x1f00
> #define PCI_PASID_CTRL 0x06 /* PASID control register */
> #define PCI_PASID_CTRL_ENABLE 0x0001 /* Enable bit */
> #define PCI_PASID_CTRL_EXEC 0x0002 /* Exec permissions Enable */

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

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