[v4,07/17] PCI/DOE: Provide synchronous API and use it internally

Commit Message

Lukas Wunner March 11, 2023, 2:40 p.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 <[e-mail]>
Signed-off-by: Lukas Wunner <[e-mail]>
Reviewed-by: Ming Li <[e-mail]>
Reviewed-by: Ira Weiny <[e-mail]>
Reviewed-by: Davidlohr Bueso <[e-mail]>
Reviewed-by: Dan Williams <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
---
 drivers/pci/doe.c       | 69 ++++++++++++++++++++++++++++++++---------
 include/linux/pci-doe.h |  6 +++-
 2 files changed, 59 insertions(+), 16 deletions(-)

Patch

diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index e5e9b287b976..adde8c66499c 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -321,26 +321,15 @@  static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
 	__le32 request_pl_le = cpu_to_le32(request_pl);
 	__le32 response_pl_le;
 	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_le,
-		.request_pl_sz = sizeof(request_pl),
-		.response_pl = &response_pl_le,
-		.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_le, sizeof(request_pl_le),
+		     &response_pl_le, sizeof(response_pl_le));
 	if (rc < 0)
 		return rc;
 
-	wait_for_completion(&c);
-
-	if (task.rv != sizeof(response_pl))
+	if (rc != sizeof(response_pl_le))
 		return -EIO;
 
 	response_pl = le32_to_cpu(response_pl_le);
@@ -552,3 +541,53 @@  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.
+ *
+ * Payloads are treated as opaque byte streams which are transmitted verbatim,
+ * without byte-swapping.  If payloads contain little-endian register values,
+ * the caller is responsible for conversion with cpu_to_le32() / le32_to_cpu().
+ *
+ * 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 43765eaf2342..5dcd54f892e5 100644
--- a/include/linux/pci-doe.h
+++ b/include/linux/pci-doe.h
@@ -49,7 +49,7 @@  struct pci_doe_mb;
  */
 struct pci_doe_task {
 	struct pci_doe_protocol prot;
-	__le32 *request_pl;
+	const __le32 *request_pl;
 	size_t request_pl_sz;
 	__le32 *response_pl;
 	size_t response_pl_sz;
@@ -78,4 +78,8 @@  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