[PATCH] PCI/VPD: Add helper pci_get_func0_dev

[PATCH] PCI/VPD: Add helper pci_get_func0_dev

[Heiner Kallweit]

The combined use of the PCI_DEVFN() and PCI_SLOT() macros in several
places is unnecessarily complex. Use a simplified version and add
a helper for it.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/pci/vpd.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
index 42f762ab0..60573f27a 100644
--- a/drivers/pci/vpd.c
+++ b/drivers/pci/vpd.c
@@ -28,6 +28,12 @@ struct pci_vpd {
 	unsigned int	valid:1;
 };
 
+static struct pci_dev *pci_get_func0_dev(struct pci_dev *dev)
+{
+	/* bits 2:0 in devfn is the device function */
+	return pci_get_slot(dev->bus, dev->devfn & 0xf8);
+}
+
 /**
  * pci_read_vpd - Read one entry from Vital Product Data
  * @dev:	pci device struct
@@ -305,8 +311,7 @@ static const struct pci_vpd_ops pci_vpd_ops = {
 static ssize_t pci_vpd_f0_read(struct pci_dev *dev, loff_t pos, size_t count,
 			       void *arg)
 {
-	struct pci_dev *tdev = pci_get_slot(dev->bus,
-					    PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
+	struct pci_dev *tdev = pci_get_func0_dev(dev);
 	ssize_t ret;
 
 	if (!tdev)
@@ -320,8 +325,7 @@ static ssize_t pci_vpd_f0_read(struct pci_dev *dev, loff_t pos, size_t count,
 static ssize_t pci_vpd_f0_write(struct pci_dev *dev, loff_t pos, size_t count,
 				const void *arg)
 {
-	struct pci_dev *tdev = pci_get_slot(dev->bus,
-					    PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
+	struct pci_dev *tdev = pci_get_func0_dev(dev);
 	ssize_t ret;
 
 	if (!tdev)
@@ -414,7 +418,7 @@ static void quirk_f0_vpd_link(struct pci_dev *dev)
 	if (!PCI_FUNC(dev->devfn))
 		return;
 
-	f0 = pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
+	f0 = pci_get_func0_dev(dev);
 	if (!f0)
 		return;
 
-- 
2.31.1

Re: [PATCH] PCI/VPD: Add helper pci_get_func0_dev

[Bjorn Helgaas]

On Fri, Apr 16, 2021 at 09:52:07PM +0200, Heiner Kallweit wrote:
> The combined use of the PCI_DEVFN() and PCI_SLOT() macros in several
> places is unnecessarily complex. Use a simplified version and add
> a helper for it.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

Applied with pci_get_func0_dev() as follows to pci/vpd for v5.13.
It's true that "devfn & 0xf8" is simpler, but it also exposes
implementation details that need not be exposed here.

  diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
  index b23bbab6802d..03a02af5a6a7 100644
  --- a/drivers/pci/vpd.c
  +++ b/drivers/pci/vpd.c
  @@ -28,6 +28,11 @@ struct pci_vpd {
	  unsigned int	valid:1;
   };
   
  +static struct pci_dev *pci_get_func0_dev(struct pci_dev *dev)
  +{
  +	return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
  +}
  +

> ---
>  drivers/pci/vpd.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
> index 42f762ab0..60573f27a 100644
> --- a/drivers/pci/vpd.c
> +++ b/drivers/pci/vpd.c
> @@ -28,6 +28,12 @@ struct pci_vpd {
>  	unsigned int	valid:1;
>  };
>  
> +static struct pci_dev *pci_get_func0_dev(struct pci_dev *dev)
> +{
> +	/* bits 2:0 in devfn is the device function */
> +	return pci_get_slot(dev->bus, dev->devfn & 0xf8);
> +}
> +
>  /**
>   * pci_read_vpd - Read one entry from Vital Product Data
>   * @dev:	pci device struct
> @@ -305,8 +311,7 @@ static const struct pci_vpd_ops pci_vpd_ops = {
>  static ssize_t pci_vpd_f0_read(struct pci_dev *dev, loff_t pos, size_t count,
>  			       void *arg)
>  {
> -	struct pci_dev *tdev = pci_get_slot(dev->bus,
> -					    PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> +	struct pci_dev *tdev = pci_get_func0_dev(dev);
>  	ssize_t ret;
>  
>  	if (!tdev)
> @@ -320,8 +325,7 @@ static ssize_t pci_vpd_f0_read(struct pci_dev *dev, loff_t pos, size_t count,
>  static ssize_t pci_vpd_f0_write(struct pci_dev *dev, loff_t pos, size_t count,
>  				const void *arg)
>  {
> -	struct pci_dev *tdev = pci_get_slot(dev->bus,
> -					    PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> +	struct pci_dev *tdev = pci_get_func0_dev(dev);
>  	ssize_t ret;
>  
>  	if (!tdev)
> @@ -414,7 +418,7 @@ static void quirk_f0_vpd_link(struct pci_dev *dev)
>  	if (!PCI_FUNC(dev->devfn))
>  		return;
>  
> -	f0 = pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> +	f0 = pci_get_func0_dev(dev);
>  	if (!f0)
>  		return;
>  
> -- 
> 2.31.1
>