diff mbox series

[v2,03/10] PCI/DOE: Provide synchronous API and use it internally

Message ID b589059ddc82039f00d695d75ac4017504df6bf6.1674468099.git.lukas@wunner.de (mailing list archive)
State Superseded
Delegated to: Bjorn Helgaas
Headers show
Series Collection of DOE material | expand

Commit Message

Lukas Wunner Jan. 23, 2023, 10:13 a.m. UTC 
The DOE API only allows asynchronous exchanges and forces callers to
provide a completion callback.  Yet all existing callers only perform
synchronous exchanges.  Upcoming commits for CMA (Component Measurement
and Authentication, PCIe r6.0 sec 6.31) likewise require only
synchronous DOE exchanges.

Provide a synchronous pci_doe() API call which builds on the internal
asynchronous machinery.

Convert the internal pci_doe_discovery() to the new call.

The new API allows submission of const-declared requests, necessitating
the addition of a const qualifier in struct pci_doe_task.

Tested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
---
 drivers/pci/doe.c       | 65 +++++++++++++++++++++++++++++++----------
 include/linux/pci-doe.h |  6 +++-
 2 files changed, 55 insertions(+), 16 deletions(-)

Comments

Ira Weiny Jan. 24, 2023, 12:48 a.m. UTC | #1 
Lukas Wunner wrote:
> The DOE API only allows asynchronous exchanges and forces callers to
> provide a completion callback.  Yet all existing callers only perform
> synchronous exchanges.  Upcoming commits for CMA (Component Measurement
> and Authentication, PCIe r6.0 sec 6.31) likewise require only
> synchronous DOE exchanges.
> 
> Provide a synchronous pci_doe() API call which builds on the internal
> asynchronous machinery.
> 
> Convert the internal pci_doe_discovery() to the new call.
> 
> The new API allows submission of const-declared requests, necessitating
> the addition of a const qualifier in struct pci_doe_task.
> 
> Tested-by: Ira Weiny <ira.weiny@intel.com>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> ---
>  drivers/pci/doe.c       | 65 +++++++++++++++++++++++++++++++----------
>  include/linux/pci-doe.h |  6 +++-
>  2 files changed, 55 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> index 7451b5732044..dce6af2ab574 100644
> --- a/drivers/pci/doe.c
> +++ b/drivers/pci/doe.c
> @@ -319,26 +319,15 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
>  	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
>  				    *index);
>  	u32 response_pl;
> -	DECLARE_COMPLETION_ONSTACK(c);
> -	struct pci_doe_task task = {
> -		.prot.vid = PCI_VENDOR_ID_PCI_SIG,
> -		.prot.type = PCI_DOE_PROTOCOL_DISCOVERY,
> -		.request_pl = &request_pl,
> -		.request_pl_sz = sizeof(request_pl),
> -		.response_pl = &response_pl,
> -		.response_pl_sz = sizeof(response_pl),
> -		.complete = pci_doe_task_complete,
> -		.private = &c,
> -	};
>  	int rc;
>  
> -	rc = pci_doe_submit_task(doe_mb, &task);
> +	rc = pci_doe(doe_mb, PCI_VENDOR_ID_PCI_SIG, PCI_DOE_PROTOCOL_DISCOVERY,
> +		     &request_pl, sizeof(request_pl),
> +		     &response_pl, sizeof(response_pl));
>  	if (rc < 0)
>  		return rc;
>  
> -	wait_for_completion(&c);
> -
> -	if (task.rv != sizeof(response_pl))
> +	if (rc != sizeof(response_pl))
>  		return -EIO;
>  
>  	*vid = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID, response_pl);
> @@ -549,3 +538,49 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(pci_doe_submit_task);
> +
> +/**
> + * pci_doe() - Perform Data Object Exchange
> + *
> + * @doe_mb: DOE Mailbox
> + * @vendor: Vendor ID
> + * @type: Data Object Type
> + * @request: Request payload
> + * @request_sz: Size of request payload (bytes)
> + * @response: Response payload
> + * @response_sz: Size of response payload (bytes)
> + *
> + * Submit @request to @doe_mb and store the @response.
> + * The DOE exchange is performed synchronously and may therefore sleep.
> + *
> + * RETURNS: Length of received response or negative errno.
> + * Received data in excess of @response_sz is discarded.
> + * The length may be smaller than @response_sz and the caller
> + * is responsible for checking that.
> + */
> +int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
> +	    const void *request, size_t request_sz,
> +	    void *response, size_t response_sz)
> +{
> +	DECLARE_COMPLETION_ONSTACK(c);
> +	struct pci_doe_task task = {
> +		.prot.vid = vendor,
> +		.prot.type = type,
> +		.request_pl = request,
> +		.request_pl_sz = request_sz,
> +		.response_pl = response,
> +		.response_pl_sz = response_sz,
> +		.complete = pci_doe_task_complete,
> +		.private = &c,
> +	};
> +	int rc;
> +
> +	rc = pci_doe_submit_task(doe_mb, &task);
> +	if (rc)
> +		return rc;
> +
> +	wait_for_completion(&c);
> +
> +	return task.rv;
> +}
> +EXPORT_SYMBOL_GPL(pci_doe);
> diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
> index ed9b4df792b8..1608e1536284 100644
> --- a/include/linux/pci-doe.h
> +++ b/include/linux/pci-doe.h
> @@ -45,7 +45,7 @@ struct pci_doe_mb;
>   */
>  struct pci_doe_task {
>  	struct pci_doe_protocol prot;
> -	u32 *request_pl;
> +	const u32 *request_pl;
>  	size_t request_pl_sz;
>  	u32 *response_pl;
>  	size_t response_pl_sz;
> @@ -74,4 +74,8 @@ struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset);
>  bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type);
>  int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task);
>  
> +int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
> +	    const void *request, size_t request_sz,
> +	    void *response, size_t response_sz);
> +
>  #endif
> -- 
> 2.39.1
>
Jonathan Cameron Jan. 24, 2023, 10:40 a.m. UTC | #2 
On Mon, 23 Jan 2023 11:13:00 +0100
Lukas Wunner <lukas@wunner.de> wrote:

> The DOE API only allows asynchronous exchanges and forces callers to
> provide a completion callback.  Yet all existing callers only perform
> synchronous exchanges.  Upcoming commits for CMA (Component Measurement
> and Authentication, PCIe r6.0 sec 6.31) likewise require only
> synchronous DOE exchanges.
> 
> Provide a synchronous pci_doe() API call which builds on the internal
> asynchronous machinery.
> 
> Convert the internal pci_doe_discovery() to the new call.
> 
> The new API allows submission of const-declared requests, necessitating
> the addition of a const qualifier in struct pci_doe_task.
> 
> Tested-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>

Pushing the struct down is fine by me, though I'll note we had it
pretty much like this in one of the earlier versions and got a
request to use a struct instead to wrap up all the parameters.

Let's see if experience convinces people this is the right
approach this time :) It is perhaps easier to argue
now the completion is moved down as well as we'd end up with
a messy case of some elements of the structure being set in the
caller and others inside where it is called (or some messy
wrapper structures).  Been a while, but I don't think we had
such a strong argument in favour of this approach back then.

The const changes makes sense independent of the rest.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>


> ---
>  drivers/pci/doe.c       | 65 +++++++++++++++++++++++++++++++----------
>  include/linux/pci-doe.h |  6 +++-
>  2 files changed, 55 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> index 7451b5732044..dce6af2ab574 100644
> --- a/drivers/pci/doe.c
> +++ b/drivers/pci/doe.c
> @@ -319,26 +319,15 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
>  	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
>  				    *index);
>  	u32 response_pl;
> -	DECLARE_COMPLETION_ONSTACK(c);
> -	struct pci_doe_task task = {
> -		.prot.vid = PCI_VENDOR_ID_PCI_SIG,
> -		.prot.type = PCI_DOE_PROTOCOL_DISCOVERY,
> -		.request_pl = &request_pl,
> -		.request_pl_sz = sizeof(request_pl),
> -		.response_pl = &response_pl,
> -		.response_pl_sz = sizeof(response_pl),
> -		.complete = pci_doe_task_complete,
> -		.private = &c,
> -	};
>  	int rc;
>  
> -	rc = pci_doe_submit_task(doe_mb, &task);
> +	rc = pci_doe(doe_mb, PCI_VENDOR_ID_PCI_SIG, PCI_DOE_PROTOCOL_DISCOVERY,
> +		     &request_pl, sizeof(request_pl),
> +		     &response_pl, sizeof(response_pl));
>  	if (rc < 0)
>  		return rc;
>  
> -	wait_for_completion(&c);
> -
> -	if (task.rv != sizeof(response_pl))
> +	if (rc != sizeof(response_pl))
>  		return -EIO;
>  
>  	*vid = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID, response_pl);
> @@ -549,3 +538,49 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(pci_doe_submit_task);
> +
> +/**
> + * pci_doe() - Perform Data Object Exchange
> + *
> + * @doe_mb: DOE Mailbox
> + * @vendor: Vendor ID
> + * @type: Data Object Type
> + * @request: Request payload
> + * @request_sz: Size of request payload (bytes)
> + * @response: Response payload
> + * @response_sz: Size of response payload (bytes)
> + *
> + * Submit @request to @doe_mb and store the @response.
> + * The DOE exchange is performed synchronously and may therefore sleep.
> + *
> + * RETURNS: Length of received response or negative errno.
> + * Received data in excess of @response_sz is discarded.
> + * The length may be smaller than @response_sz and the caller
> + * is responsible for checking that.
> + */
> +int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
> +	    const void *request, size_t request_sz,
> +	    void *response, size_t response_sz)
> +{
> +	DECLARE_COMPLETION_ONSTACK(c);
> +	struct pci_doe_task task = {
> +		.prot.vid = vendor,
> +		.prot.type = type,
> +		.request_pl = request,
> +		.request_pl_sz = request_sz,
> +		.response_pl = response,
> +		.response_pl_sz = response_sz,
> +		.complete = pci_doe_task_complete,
> +		.private = &c,
> +	};
> +	int rc;
> +
> +	rc = pci_doe_submit_task(doe_mb, &task);
> +	if (rc)
> +		return rc;
> +
> +	wait_for_completion(&c);
> +
> +	return task.rv;
> +}
> +EXPORT_SYMBOL_GPL(pci_doe);
> diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
> index ed9b4df792b8..1608e1536284 100644
> --- a/include/linux/pci-doe.h
> +++ b/include/linux/pci-doe.h
> @@ -45,7 +45,7 @@ struct pci_doe_mb;
>   */
>  struct pci_doe_task {
>  	struct pci_doe_protocol prot;
> -	u32 *request_pl;
> +	const u32 *request_pl;
>  	size_t request_pl_sz;
>  	u32 *response_pl;
>  	size_t response_pl_sz;
> @@ -74,4 +74,8 @@ struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset);
>  bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type);
>  int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task);
>  
> +int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
> +	    const void *request, size_t request_sz,
> +	    void *response, size_t response_sz);
> +
>  #endif
Ira Weiny Jan. 24, 2023, 8:07 p.m. UTC | #3 
Jonathan Cameron wrote:
> On Mon, 23 Jan 2023 11:13:00 +0100
> Lukas Wunner <lukas@wunner.de> wrote:
> 
> > The DOE API only allows asynchronous exchanges and forces callers to
> > provide a completion callback.  Yet all existing callers only perform
> > synchronous exchanges.  Upcoming commits for CMA (Component Measurement
> > and Authentication, PCIe r6.0 sec 6.31) likewise require only
> > synchronous DOE exchanges.
> > 
> > Provide a synchronous pci_doe() API call which builds on the internal
> > asynchronous machinery.
> > 
> > Convert the internal pci_doe_discovery() to the new call.
> > 
> > The new API allows submission of const-declared requests, necessitating
> > the addition of a const qualifier in struct pci_doe_task.
> > 
> > Tested-by: Ira Weiny <ira.weiny@intel.com>
> > Signed-off-by: Lukas Wunner <lukas@wunner.de>
> > Cc: Dan Williams <dan.j.williams@intel.com>
> > Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> 
> Pushing the struct down is fine by me, though I'll note we had it
> pretty much like this in one of the earlier versions and got a
> request to use a struct instead to wrap up all the parameters.

I had the same thought but decided not to pick at that old wound...  ;-)

> 
> Let's see if experience convinces people this is the right
> approach this time :) It is perhaps easier to argue
> now the completion is moved down as well as we'd end up with
> a messy case of some elements of the structure being set in the
> caller and others inside where it is called (or some messy
> wrapper structures).  Been a while, but I don't think we had
> such a strong argument in favour of this approach back then.

I think this makes a lot of sense and is clean enough.  I don't think the
number of parameters is outrageous.

Ira

> 
> The const changes makes sense independent of the rest.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> 
> > ---
> >  drivers/pci/doe.c       | 65 +++++++++++++++++++++++++++++++----------
> >  include/linux/pci-doe.h |  6 +++-
> >  2 files changed, 55 insertions(+), 16 deletions(-)
> > 
> > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> > index 7451b5732044..dce6af2ab574 100644
> > --- a/drivers/pci/doe.c
> > +++ b/drivers/pci/doe.c
> > @@ -319,26 +319,15 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
> >  	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
> >  				    *index);
> >  	u32 response_pl;
> > -	DECLARE_COMPLETION_ONSTACK(c);
> > -	struct pci_doe_task task = {
> > -		.prot.vid = PCI_VENDOR_ID_PCI_SIG,
> > -		.prot.type = PCI_DOE_PROTOCOL_DISCOVERY,
> > -		.request_pl = &request_pl,
> > -		.request_pl_sz = sizeof(request_pl),
> > -		.response_pl = &response_pl,
> > -		.response_pl_sz = sizeof(response_pl),
> > -		.complete = pci_doe_task_complete,
> > -		.private = &c,
> > -	};
> >  	int rc;
> >  
> > -	rc = pci_doe_submit_task(doe_mb, &task);
> > +	rc = pci_doe(doe_mb, PCI_VENDOR_ID_PCI_SIG, PCI_DOE_PROTOCOL_DISCOVERY,
> > +		     &request_pl, sizeof(request_pl),
> > +		     &response_pl, sizeof(response_pl));
> >  	if (rc < 0)
> >  		return rc;
> >  
> > -	wait_for_completion(&c);
> > -
> > -	if (task.rv != sizeof(response_pl))
> > +	if (rc != sizeof(response_pl))
> >  		return -EIO;
> >  
> >  	*vid = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID, response_pl);
> > @@ -549,3 +538,49 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
> >  	return 0;
> >  }
> >  EXPORT_SYMBOL_GPL(pci_doe_submit_task);
> > +
> > +/**
> > + * pci_doe() - Perform Data Object Exchange
> > + *
> > + * @doe_mb: DOE Mailbox
> > + * @vendor: Vendor ID
> > + * @type: Data Object Type
> > + * @request: Request payload
> > + * @request_sz: Size of request payload (bytes)
> > + * @response: Response payload
> > + * @response_sz: Size of response payload (bytes)
> > + *
> > + * Submit @request to @doe_mb and store the @response.
> > + * The DOE exchange is performed synchronously and may therefore sleep.
> > + *
> > + * RETURNS: Length of received response or negative errno.
> > + * Received data in excess of @response_sz is discarded.
> > + * The length may be smaller than @response_sz and the caller
> > + * is responsible for checking that.
> > + */
> > +int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
> > +	    const void *request, size_t request_sz,
> > +	    void *response, size_t response_sz)
> > +{
> > +	DECLARE_COMPLETION_ONSTACK(c);
> > +	struct pci_doe_task task = {
> > +		.prot.vid = vendor,
> > +		.prot.type = type,
> > +		.request_pl = request,
> > +		.request_pl_sz = request_sz,
> > +		.response_pl = response,
> > +		.response_pl_sz = response_sz,
> > +		.complete = pci_doe_task_complete,
> > +		.private = &c,
> > +	};
> > +	int rc;
> > +
> > +	rc = pci_doe_submit_task(doe_mb, &task);
> > +	if (rc)
> > +		return rc;
> > +
> > +	wait_for_completion(&c);
> > +
> > +	return task.rv;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_doe);
> > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
> > index ed9b4df792b8..1608e1536284 100644
> > --- a/include/linux/pci-doe.h
> > +++ b/include/linux/pci-doe.h
> > @@ -45,7 +45,7 @@ struct pci_doe_mb;
> >   */
> >  struct pci_doe_task {
> >  	struct pci_doe_protocol prot;
> > -	u32 *request_pl;
> > +	const u32 *request_pl;
> >  	size_t request_pl_sz;
> >  	u32 *response_pl;
> >  	size_t response_pl_sz;
> > @@ -74,4 +74,8 @@ struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset);
> >  bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type);
> >  int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task);
> >  
> > +int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
> > +	    const void *request, size_t request_sz,
> > +	    void *response, size_t response_sz);
> > +
> >  #endif
>
Dan Williams Feb. 10, 2023, 11:57 p.m. UTC | #4 
Lukas Wunner wrote:
> The DOE API only allows asynchronous exchanges and forces callers to
> provide a completion callback.  Yet all existing callers only perform
> synchronous exchanges.  Upcoming commits for CMA (Component Measurement
> and Authentication, PCIe r6.0 sec 6.31) likewise require only
> synchronous DOE exchanges.
> 
> Provide a synchronous pci_doe() API call which builds on the internal
> asynchronous machinery.
> 
> Convert the internal pci_doe_discovery() to the new call.
> 
> The new API allows submission of const-declared requests, necessitating
> the addition of a const qualifier in struct pci_doe_task.
> 
> Tested-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>

While I do wish there was a way to avoid a 7-argument function I can't
think of a better way to do this that does not run afoul of the previous
problems with this interface.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
diff mbox series

Patch

diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index 7451b5732044..dce6af2ab574 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -319,26 +319,15 @@  static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
 	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
 				    *index);
 	u32 response_pl;
-	DECLARE_COMPLETION_ONSTACK(c);
-	struct pci_doe_task task = {
-		.prot.vid = PCI_VENDOR_ID_PCI_SIG,
-		.prot.type = PCI_DOE_PROTOCOL_DISCOVERY,
-		.request_pl = &request_pl,
-		.request_pl_sz = sizeof(request_pl),
-		.response_pl = &response_pl,
-		.response_pl_sz = sizeof(response_pl),
-		.complete = pci_doe_task_complete,
-		.private = &c,
-	};
 	int rc;
 
-	rc = pci_doe_submit_task(doe_mb, &task);
+	rc = pci_doe(doe_mb, PCI_VENDOR_ID_PCI_SIG, PCI_DOE_PROTOCOL_DISCOVERY,
+		     &request_pl, sizeof(request_pl),
+		     &response_pl, sizeof(response_pl));
 	if (rc < 0)
 		return rc;
 
-	wait_for_completion(&c);
-
-	if (task.rv != sizeof(response_pl))
+	if (rc != sizeof(response_pl))
 		return -EIO;
 
 	*vid = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID, response_pl);
@@ -549,3 +538,49 @@  int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pci_doe_submit_task);
+
+/**
+ * pci_doe() - Perform Data Object Exchange
+ *
+ * @doe_mb: DOE Mailbox
+ * @vendor: Vendor ID
+ * @type: Data Object Type
+ * @request: Request payload
+ * @request_sz: Size of request payload (bytes)
+ * @response: Response payload
+ * @response_sz: Size of response payload (bytes)
+ *
+ * Submit @request to @doe_mb and store the @response.
+ * The DOE exchange is performed synchronously and may therefore sleep.
+ *
+ * RETURNS: Length of received response or negative errno.
+ * Received data in excess of @response_sz is discarded.
+ * The length may be smaller than @response_sz and the caller
+ * is responsible for checking that.
+ */
+int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
+	    const void *request, size_t request_sz,
+	    void *response, size_t response_sz)
+{
+	DECLARE_COMPLETION_ONSTACK(c);
+	struct pci_doe_task task = {
+		.prot.vid = vendor,
+		.prot.type = type,
+		.request_pl = request,
+		.request_pl_sz = request_sz,
+		.response_pl = response,
+		.response_pl_sz = response_sz,
+		.complete = pci_doe_task_complete,
+		.private = &c,
+	};
+	int rc;
+
+	rc = pci_doe_submit_task(doe_mb, &task);
+	if (rc)
+		return rc;
+
+	wait_for_completion(&c);
+
+	return task.rv;
+}
+EXPORT_SYMBOL_GPL(pci_doe);
diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
index ed9b4df792b8..1608e1536284 100644
--- a/include/linux/pci-doe.h
+++ b/include/linux/pci-doe.h
@@ -45,7 +45,7 @@  struct pci_doe_mb;
  */
 struct pci_doe_task {
 	struct pci_doe_protocol prot;
-	u32 *request_pl;
+	const u32 *request_pl;
 	size_t request_pl_sz;
 	u32 *response_pl;
 	size_t response_pl_sz;
@@ -74,4 +74,8 @@  struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset);
 bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type);
 int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task);
 
+int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
+	    const void *request, size_t request_sz,
+	    void *response, size_t response_sz);
+
 #endif