Re: [PATCH v9 04/27] cxl/pci: add check for validating capabilities

From: Alejandro Lucero <redacted>

During CXL device initialization supported capabilities by the device
are discovered. Type3 and Type2 devices have different mandatory
capabilities and a Type2 expects a specific set including optional
capabilities.

Add a function for checking expected capabilities against those found
during initialization and allow those mandatory/expected capabilities to
be a subset of the capabilities found.

Rely on this function for validating capabilities instead of when CXL
regs are probed.

Signed-off-by: Alejandro Lucero <redacted>
Reviewed-by: Zhi Wang <zhiw@nvidia.com>
---
 drivers/cxl/core/pci.c  | 16 ++++++++++++++++
 drivers/cxl/core/regs.c |  9 ---------
 drivers/cxl/pci.c       | 24 ++++++++++++++++++++++++
 include/cxl/cxl.h       |  3 +++
 4 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index ec57caf5b2d7..57318cdc368a 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c

@@ -8,6 +8,7 @@
 #include <linux/pci.h>
 #include <linux/pci-doe.h>
 #include <linux/aer.h>
+#include <cxl/cxl.h>
 #include <cxlpci.h>
 #include <cxlmem.h>
 #include <cxl.h>

@@ -1055,3 +1056,18 @@ int cxl_pci_get_bandwidth(struct pci_dev *pdev, struct access_coordinate *c)
 
 	return 0;
 }
+
+bool cxl_pci_check_caps(struct cxl_dev_state *cxlds, unsigned long *expected_caps,
+			unsigned long *current_caps)
+{
+
+	if (current_caps)
+		bitmap_copy(current_caps, cxlds->capabilities, CXL_MAX_CAPS);
+
+	dev_dbg(cxlds->dev, "Checking cxlds caps 0x%pb vs expected caps 0x%pb\n",
+		cxlds->capabilities, expected_caps);
+
+	/* Checking a minimum of mandatory/expected capabilities */
+	return bitmap_subset(expected_caps, cxlds->capabilities, CXL_MAX_CAPS);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_pci_check_caps, "CXL");