cxl: Use pci_find_vsec_capability() to simplify the code

PCI core add pci_find_vsec_capability() to query VSEC. We can use that
core API to simplify the code.

The only logical change is that pci_find_vsec_capability check the
Vendor ID before finding the VSEC.

PCI spec rev 5.0 says in 7.9.5.2 Vendor-Specific Header:
  VSEC ID - This field is a vendor-defined ID number that indicates the
  nature and format of the VSEC structure
  Software must qualify the Vendor ID before interpreting this field.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230804075630.186054-1-wangxiongfeng2@huawei.com

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 0ff9448..4cf9e7c 100644 (file)
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -150,16 +150,7 @@ static inline resource_size_t p2_size(struct pci_dev *dev)
 
 static int find_cxl_vsec(struct pci_dev *dev)
 {
-       int vsec = 0;
-       u16 val;
-
-       while ((vsec = pci_find_next_ext_capability(dev, vsec, PCI_EXT_CAP_ID_VNDR))) {
-               pci_read_config_word(dev, vsec + 0x4, &val);
-               if (val == CXL_PCI_VSEC_ID)
-                       return vsec;
-       }
-       return 0;
-
+       return pci_find_vsec_capability(dev, PCI_VENDOR_ID_IBM, CXL_PCI_VSEC_ID);
 }
 
 static void dump_cxl_config_space(struct pci_dev *dev)