PCI/DOE: Provide synchronous API and use it internally

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>
Reviewed-by: Ming Li <ming4.li@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/0f444206da9615c56301fbaff459c0f45d27f122.1678543498.git.lukas@wunner.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index e5e9b287b9766e3c164bb2c2a6c1bcca72a59c96..adde8c66499cc0cc3914d42df10391823b2c4712 100644 (file)
--- 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 43765eaf2342c6996db747a14d9dcef89d6993e8..5dcd54f892e5f277f06154793ec1501a1004b989 100644 (file)
--- 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