lightnvm: introduce mlc lower page table mappings

NAND MLC memories have both lower and upper pages. When programming,
both of these must be written, before data can be read. However,
these lower and upper pages might not placed at even and odd flash
pages, but can be skipped. Therefore each flash memory has its lower
pages defined, which can then be used when programming and to know when
padding are necessary.

This patch implements the lower page definition in the specification,
and exposes it through a simple lookup table at dev->lptbl.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
index b112f02..215c025 100644
--- a/drivers/nvme/host/lightnvm.c
+++ b/drivers/nvme/host/lightnvm.c
@@ -146,6 +146,16 @@
 	};
 };
 
+struct nvme_nvm_lp_mlc {
+	__u16			num_pairs;
+	__u8			pairs[886];
+};
+
+struct nvme_nvm_lp_tbl {
+	__u8			id[8];
+	struct nvme_nvm_lp_mlc	mlc;
+};
+
 struct nvme_nvm_id_group {
 	__u8			mtype;
 	__u8			fmtype;
@@ -169,7 +179,8 @@
 	__le32			mpos;
 	__le32			mccap;
 	__le16			cpar;
-	__u8			reserved[906];
+	__u8			reserved[10];
+	struct nvme_nvm_lp_tbl lptbl;
 } __packed;
 
 struct nvme_nvm_addr_format {
@@ -266,6 +277,15 @@
 		dst->mccap = le32_to_cpu(src->mccap);
 
 		dst->cpar = le16_to_cpu(src->cpar);
+
+		if (dst->fmtype == NVM_ID_FMTYPE_MLC) {
+			memcpy(dst->lptbl.id, src->lptbl.id, 8);
+			dst->lptbl.mlc.num_pairs =
+					le16_to_cpu(src->lptbl.mlc.num_pairs);
+			/* 4 bits per pair */
+			memcpy(dst->lptbl.mlc.pairs, src->lptbl.mlc.pairs,
+						dst->lptbl.mlc.num_pairs >> 1);
+		}
 	}
 
 	return 0;