[PATCH 0/2] introduce pci_find_next_dvsec_capability() to simplify the code

[PATCH 0/2] introduce pci_find_next_dvsec_capability() to simplify the code

[Xiongfeng Wang]

Some devices may have several DVSEC(Designated Vendor-Specific Extended
Capability) entries with the same DVSEC ID. Introduce
pci_find_next_dvsec_capability() to simplify the code.

Xiongfeng Wang (2):
  PCI: Add pci_find_next_dvsec_capability to find next designated VSEC
  ocxl: use pci_find_next_dvsec_capability() to simplify the code

 arch/powerpc/platforms/powernv/ocxl.c | 20 ++-------------
 drivers/misc/ocxl/config.c            | 21 +++++----------
 drivers/pci/pci.c                     | 37 ++++++++++++++++++---------
 include/linux/pci.h                   |  2 ++
 include/misc/ocxl-config.h            |  4 ---
 5 files changed, 35 insertions(+), 49 deletions(-)

-- 
2.20.1

[PATCH 1/2] PCI: Add pci_find_next_dvsec_capability to find next designated VSEC

[Xiongfeng Wang]

Some devices may have several DVSEC(Designated Vendor-Specific Extended
Capability) entries with the same DVSEC ID. Add
pci_find_next_dvsec_capability() to find them all.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
---
 drivers/pci/pci.c   | 37 +++++++++++++++++++++++++------------
 include/linux/pci.h |  2 ++
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 60230da957e0..3455ca7306ae 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -749,35 +749,48 @@ u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap)
 EXPORT_SYMBOL_GPL(pci_find_vsec_capability);
 
 /**
- * pci_find_dvsec_capability - Find DVSEC for vendor
+ * pci_find_next_dvsec_capability - Find next DVSEC for vendor
  * @dev: PCI device to query
+ * @start: address at which to start looking (0 to start at beginning of list)
  * @vendor: Vendor ID to match for the DVSEC
  * @dvsec: Designated Vendor-specific capability ID
  *
- * If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the capability
- * offset in config space; otherwise return 0.
+ * Returns the address of the next DVSEC if the DVSEC has Vendor ID @vendor and
+ * DVSEC ID @dvsec; otherwise return 0. DVSEC can occur several times with the
+ * same DVSEC ID for some devices, and this provides a way to find them all.
  */
-u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec)
+u16 pci_find_next_dvsec_capability(struct pci_dev *dev, u16 start, u16 vendor,
+				   u16 dvsec)
 {
-	int pos;
+	u16 pos = start;
 
-	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DVSEC);
-	if (!pos)
-		return 0;
-
-	while (pos) {
+	while ((pos = pci_find_next_ext_capability(dev, pos,
+						  PCI_EXT_CAP_ID_DVSEC))) {
 		u16 v, id;
 
 		pci_read_config_word(dev, pos + PCI_DVSEC_HEADER1, &v);
 		pci_read_config_word(dev, pos + PCI_DVSEC_HEADER2, &id);
 		if (vendor == v && dvsec == id)
 			return pos;
-
-		pos = pci_find_next_ext_capability(dev, pos, PCI_EXT_CAP_ID_DVSEC);
 	}
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(pci_find_next_dvsec_capability);
+
+/**
+ * pci_find_dvsec_capability - Find DVSEC for vendor
+ * @dev: PCI device to query
+ * @vendor: Vendor ID to match for the DVSEC
+ * @dvsec: Designated Vendor-specific capability ID
+ *
+ * If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the capability
+ * offset in config space; otherwise return 0.
+ */
+u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec)
+{
+	return pci_find_next_dvsec_capability(dev, 0, vendor, dvsec);
+}
 EXPORT_SYMBOL_GPL(pci_find_dvsec_capability);
 
 /**
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c69a2cc1f412..82bb905daf72 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1168,6 +1168,8 @@ u16 pci_find_next_ext_capability(struct pci_dev *dev, u16 pos, int cap);
 struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
 u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap);
 u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec);
+u16 pci_find_next_dvsec_capability(struct pci_dev *dev, u16 start, u16 vendor,
+				   u16 dvsec);
 
 u64 pci_get_dsn(struct pci_dev *dev);
 
-- 
2.20.1

[PATCH 2/2] ocxl: use pci_find_next_dvsec_capability() to simplify the code

[Xiongfeng Wang]

PCI core add pci_find_next_dvsec_capability() to query the next DVSEC.
We can use that core API to simplify the code. Also remove the unused
macros.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
---
 arch/powerpc/platforms/powernv/ocxl.c | 20 ++------------------
 drivers/misc/ocxl/config.c            | 21 ++++++---------------
 include/misc/ocxl-config.h            |  4 ----
 3 files changed, 8 insertions(+), 37 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index 629067781cec..8dbc1a9535fc 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -71,29 +71,13 @@ static DEFINE_MUTEX(links_list_lock);
  * the AFUs, by pro-rating if needed.
  */
 
-static int find_dvsec_from_pos(struct pci_dev *dev, int dvsec_id, int pos)
-{
-	int vsec = pos;
-	u16 vendor, id;
-
-	while ((vsec = pci_find_next_ext_capability(dev, vsec,
-						    OCXL_EXT_CAP_ID_DVSEC))) {
-		pci_read_config_word(dev, vsec + OCXL_DVSEC_VENDOR_OFFSET,
-				&vendor);
-		pci_read_config_word(dev, vsec + OCXL_DVSEC_ID_OFFSET, &id);
-		if (vendor == PCI_VENDOR_ID_IBM && id == dvsec_id)
-			return vsec;
-	}
-	return 0;
-}
-
 static int find_dvsec_afu_ctrl(struct pci_dev *dev, u8 afu_idx)
 {
 	int vsec = 0;
 	u8 idx;
 
-	while ((vsec = find_dvsec_from_pos(dev, OCXL_DVSEC_AFU_CTRL_ID,
-					   vsec))) {
+	while ((vsec = pci_find_next_dvsec_capability(dev, vsec,
+				PCI_VENDOR_ID_IBM, OCXL_DVSEC_AFU_CTRL_ID))) {
 		pci_read_config_byte(dev, vsec + OCXL_DVSEC_AFU_CTRL_AFU_IDX,
 				&idx);
 		if (idx == afu_idx)
diff --git a/drivers/misc/ocxl/config.c b/drivers/misc/ocxl/config.c
index 92ab49705f64..6c0fca32e6db 100644
--- a/drivers/misc/ocxl/config.c
+++ b/drivers/misc/ocxl/config.c
@@ -39,23 +39,14 @@ static int find_dvsec(struct pci_dev *dev, int dvsec_id)
 static int find_dvsec_afu_ctrl(struct pci_dev *dev, u8 afu_idx)
 {
 	int vsec = 0;
-	u16 vendor, id;
 	u8 idx;
 
-	while ((vsec = pci_find_next_ext_capability(dev, vsec,
-						    OCXL_EXT_CAP_ID_DVSEC))) {
-		pci_read_config_word(dev, vsec + OCXL_DVSEC_VENDOR_OFFSET,
-				&vendor);
-		pci_read_config_word(dev, vsec + OCXL_DVSEC_ID_OFFSET, &id);
-
-		if (vendor == PCI_VENDOR_ID_IBM &&
-			id == OCXL_DVSEC_AFU_CTRL_ID) {
-			pci_read_config_byte(dev,
-					vsec + OCXL_DVSEC_AFU_CTRL_AFU_IDX,
-					&idx);
-			if (idx == afu_idx)
-				return vsec;
-		}
+	while ((vsec = pci_find_next_dvsec_capability(dev, vsec,
+				PCI_VENDOR_ID_IBM, OCXL_DVSEC_AFU_CTRL_ID))) {
+		pci_read_config_byte(dev, vsec + OCXL_DVSEC_AFU_CTRL_AFU_IDX,
+				     &idx);
+		if (idx == afu_idx)
+			return vsec;
 	}
 	return 0;
 }
diff --git a/include/misc/ocxl-config.h b/include/misc/ocxl-config.h
index ccfd3b463517..40cf1b143170 100644
--- a/include/misc/ocxl-config.h
+++ b/include/misc/ocxl-config.h
@@ -10,10 +10,6 @@
  * It follows the specification for opencapi 3.0
  */
 
-#define OCXL_EXT_CAP_ID_DVSEC                 0x23
-
-#define OCXL_DVSEC_VENDOR_OFFSET              0x4
-#define OCXL_DVSEC_ID_OFFSET                  0x8
 #define OCXL_DVSEC_TL_ID                      0xF000
 #define   OCXL_DVSEC_TL_BACKOFF_TIMERS          0x10
 #define   OCXL_DVSEC_TL_RECV_CAP                0x18
-- 
2.20.1

Re: [PATCH 1/2] PCI: Add pci_find_next_dvsec_capability to find next designated VSEC

[Andrew Donnellan]

On Mon, 2023-08-07 at 11:18 +0800, Xiongfeng Wang wrote:
> Some devices may have several DVSEC(Designated Vendor-Specific
> Extended
> Capability) entries with the same DVSEC ID. Add
> pci_find_next_dvsec_capability() to find them all.
> 
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> 

Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>

> ---
>  drivers/pci/pci.c   | 37 +++++++++++++++++++++++++------------
>  include/linux/pci.h |  2 ++
>  2 files changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0..3455ca7306ae 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -749,35 +749,48 @@ u16 pci_find_vsec_capability(struct pci_dev
> *dev, u16 vendor, int cap)
>  EXPORT_SYMBOL_GPL(pci_find_vsec_capability);
>  
>  /**
> - * pci_find_dvsec_capability - Find DVSEC for vendor
> + * pci_find_next_dvsec_capability - Find next DVSEC for vendor
>   * @dev: PCI device to query
> + * @start: address at which to start looking (0 to start at
> beginning of list)
>   * @vendor: Vendor ID to match for the DVSEC
>   * @dvsec: Designated Vendor-specific capability ID
>   *
> - * If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the
> capability
> - * offset in config space; otherwise return 0.
> + * Returns the address of the next DVSEC if the DVSEC has Vendor ID
> @vendor and
> + * DVSEC ID @dvsec; otherwise return 0. DVSEC can occur several
> times with the
> + * same DVSEC ID for some devices, and this provides a way to find
> them all.
>   */
> -u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16
> dvsec)
> +u16 pci_find_next_dvsec_capability(struct pci_dev *dev, u16 start,
> u16 vendor,
> +                                  u16 dvsec)
>  {
> -       int pos;
> +       u16 pos = start;
>  
> -       pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DVSEC);
> -       if (!pos)
> -               return 0;
> -
> -       while (pos) {
> +       while ((pos = pci_find_next_ext_capability(dev, pos,
> +                                                
> PCI_EXT_CAP_ID_DVSEC))) {
>                 u16 v, id;
>  
>                 pci_read_config_word(dev, pos + PCI_DVSEC_HEADER1,
> &v);
>                 pci_read_config_word(dev, pos + PCI_DVSEC_HEADER2,
> &id);
>                 if (vendor == v && dvsec == id)
>                         return pos;
> -
> -               pos = pci_find_next_ext_capability(dev, pos,
> PCI_EXT_CAP_ID_DVSEC);
>         }
>  
>         return 0;
>  }
> +EXPORT_SYMBOL_GPL(pci_find_next_dvsec_capability);
> +
> +/**
> + * pci_find_dvsec_capability - Find DVSEC for vendor
> + * @dev: PCI device to query
> + * @vendor: Vendor ID to match for the DVSEC
> + * @dvsec: Designated Vendor-specific capability ID
> + *
> + * If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the
> capability
> + * offset in config space; otherwise return 0.
> + */
> +u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16
> dvsec)
> +{
> +       return pci_find_next_dvsec_capability(dev, 0, vendor, dvsec);
> +}
>  EXPORT_SYMBOL_GPL(pci_find_dvsec_capability);
>  
>  /**
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c69a2cc1f412..82bb905daf72 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1168,6 +1168,8 @@ u16 pci_find_next_ext_capability(struct pci_dev
> *dev, u16 pos, int cap);
>  struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
>  u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int
> cap);
>  u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16
> dvsec);
> +u16 pci_find_next_dvsec_capability(struct pci_dev *dev, u16 start,
> u16 vendor,
> +                                  u16 dvsec);
>  
>  u64 pci_get_dsn(struct pci_dev *dev);
>  

-- 
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited

Re: [PATCH 2/2] ocxl: use pci_find_next_dvsec_capability() to simplify the code

[Andrew Donnellan]

On Mon, 2023-08-07 at 11:18 +0800, Xiongfeng Wang wrote:
> PCI core add pci_find_next_dvsec_capability() to query the next
> DVSEC.
> We can use that core API to simplify the code. Also remove the unused
> macros.
> 
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>

Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>


-- 
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited

Re: [PATCH 1/2] PCI: Add pci_find_next_dvsec_capability to find next designated VSEC

[Bjorn Helgaas]

[+cc David since drivers/platform/x86/intel/vsec.c does some similar
things, although it seems to iterate over all Intel DVSEC IDs at once]

In subject:

  PCI: Add pci_find_next_dvsec_capability() to find next Designated VSEC

On Mon, Aug 07, 2023 at 11:18:45AM +0800, Xiongfeng Wang wrote:
> Some devices may have several DVSEC(Designated Vendor-Specific Extended
> Capability) entries with the same DVSEC ID. Add
> pci_find_next_dvsec_capability() to find them all.

Add space between "DVSEC" and "(Designated ...)".

> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

so you can merge this along with the ocxl patch that uses it.

> ---
>  drivers/pci/pci.c   | 37 +++++++++++++++++++++++++------------
>  include/linux/pci.h |  2 ++
>  2 files changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0..3455ca7306ae 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -749,35 +749,48 @@ u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap)
>  EXPORT_SYMBOL_GPL(pci_find_vsec_capability);
>  
>  /**
> - * pci_find_dvsec_capability - Find DVSEC for vendor
> + * pci_find_next_dvsec_capability - Find next DVSEC for vendor
>   * @dev: PCI device to query
> + * @start: address at which to start looking (0 to start at beginning of list)

s/address/Address/ to match other parameters

>   * @vendor: Vendor ID to match for the DVSEC
>   * @dvsec: Designated Vendor-specific capability ID

There are a lot of IDs floating around here, so to better match the
spec language:

  @dvsec: Vendor-defined DVSEC ID

> - * If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the capability
> - * offset in config space; otherwise return 0.
> + * Returns the address of the next DVSEC if the DVSEC has Vendor ID @vendor and
> + * DVSEC ID @dvsec; otherwise return 0. DVSEC can occur several times with the
> + * same DVSEC ID for some devices, and this provides a way to find them all.
>   */
> -u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec)
> +u16 pci_find_next_dvsec_capability(struct pci_dev *dev, u16 start, u16 vendor,
> +				   u16 dvsec)
>  {
> -	int pos;
> +	u16 pos = start;
>  
> -	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DVSEC);
> -	if (!pos)
> -		return 0;
> -
> -	while (pos) {
> +	while ((pos = pci_find_next_ext_capability(dev, pos,
> +						  PCI_EXT_CAP_ID_DVSEC))) {
>  		u16 v, id;
>  
>  		pci_read_config_word(dev, pos + PCI_DVSEC_HEADER1, &v);
>  		pci_read_config_word(dev, pos + PCI_DVSEC_HEADER2, &id);
>  		if (vendor == v && dvsec == id)
>  			return pos;
> -
> -		pos = pci_find_next_ext_capability(dev, pos, PCI_EXT_CAP_ID_DVSEC);
>  	}
>  
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(pci_find_next_dvsec_capability);
> +
> +/**
> + * pci_find_dvsec_capability - Find DVSEC for vendor
> + * @dev: PCI device to query
> + * @vendor: Vendor ID to match for the DVSEC
> + * @dvsec: Designated Vendor-specific capability ID
> + *
> + * If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the capability
> + * offset in config space; otherwise return 0.
> + */
> +u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec)
> +{
> +	return pci_find_next_dvsec_capability(dev, 0, vendor, dvsec);
> +}
>  EXPORT_SYMBOL_GPL(pci_find_dvsec_capability);
>  
>  /**
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c69a2cc1f412..82bb905daf72 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1168,6 +1168,8 @@ u16 pci_find_next_ext_capability(struct pci_dev *dev, u16 pos, int cap);
>  struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
>  u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap);
>  u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec);
> +u16 pci_find_next_dvsec_capability(struct pci_dev *dev, u16 start, u16 vendor,
> +				   u16 dvsec);
>  
>  u64 pci_get_dsn(struct pci_dev *dev);
>  
> -- 
> 2.20.1
>