nfp: use PluDevice register for model for non-NFP6000 chips

The model number for NFP3800 and newer devices can be completely
derived from PluDevice register without subtracting 0x10.
Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: Fei Qin <fei.qin@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cpplib.c

@@ -22,6 +22,7 @@
 #include "nfp6000/nfp_xpb.h"
 
 /* NFP6000 PL */
+#define NFP_PL_DEVICE_PART_NFP6000		0x6200
 #define NFP_PL_DEVICE_ID			0x00000004
 #define   NFP_PL_DEVICE_ID_MASK			GENMASK(7, 0)
 #define   NFP_PL_DEVICE_PART_MASK		GENMASK(31, 16)
@@ -130,8 +131,12 @@ int nfp_cpp_model_autodetect(struct nfp_cpp *cpp, u32 *model)
 		return err;
 
 	*model = reg & NFP_PL_DEVICE_MODEL_MASK;
+	/* Disambiguate the NFP4000/NFP5000/NFP6000 chips */
+	if (FIELD_GET(NFP_PL_DEVICE_PART_MASK, reg) ==
+	    NFP_PL_DEVICE_PART_NFP6000) {
 		if (*model & NFP_PL_DEVICE_ID_MASK)
 			*model -= 0x10;
+	}
 
 	return 0;
 }