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 <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/lightnvm/core.c

···
 }
 EXPORT_SYMBOL(nvm_submit_ppa);
 
+static int nvm_init_slc_tbl(struct nvm_dev *dev, struct nvm_id_group *grp)
+{
+	int i;
+
+	dev->lps_per_blk = dev->pgs_per_blk;
+	dev->lptbl = kcalloc(dev->lps_per_blk, sizeof(int), GFP_KERNEL);
+	if (!dev->lptbl)
+		return -ENOMEM;
+
+	/* Just a linear array */
+	for (i = 0; i < dev->lps_per_blk; i++)
+		dev->lptbl[i] = i;
+
+	return 0;
+}
+
+static int nvm_init_mlc_tbl(struct nvm_dev *dev, struct nvm_id_group *grp)
+{
+	int i, p;
+	struct nvm_id_lp_mlc *mlc = &grp->lptbl.mlc;
+
+	if (!mlc->num_pairs)
+		return 0;
+
+	dev->lps_per_blk = mlc->num_pairs;
+	dev->lptbl = kcalloc(dev->lps_per_blk, sizeof(int), GFP_KERNEL);
+	if (!dev->lptbl)
+		return -ENOMEM;
+
+	/* The lower page table encoding consists of a list of bytes, where each
+	 * has a lower and an upper half. The first half byte maintains the
+	 * increment value and every value after is an offset added to the
+	 * previous incrementation value */
+	dev->lptbl[0] = mlc->pairs[0] & 0xF;
+	for (i = 1; i < dev->lps_per_blk; i++) {
+		p = mlc->pairs[i >> 1];
+		if (i & 0x1) /* upper */
+			dev->lptbl[i] = dev->lptbl[i - 1] + ((p & 0xF0) >> 4);
+		else /* lower */
+			dev->lptbl[i] = dev->lptbl[i - 1] + (p & 0xF);
+	}
+
+	return 0;
+}
+
 static int nvm_core_init(struct nvm_dev *dev)
 {
 	struct nvm_id *id = &dev->identity;
···
 		return -EINVAL;
 	}
 
-	if (grp->fmtype != 0 && grp->fmtype != 1) {
+	switch (grp->fmtype) {
+	case NVM_ID_FMTYPE_SLC:
+		if (nvm_init_slc_tbl(dev, grp))
+			return -ENOMEM;
+		break;
+	case NVM_ID_FMTYPE_MLC:
+		if (nvm_init_mlc_tbl(dev, grp))
+			return -ENOMEM;
+		break;
+	default:
 		pr_err("nvm: flash type not supported\n");
 		return -EINVAL;
 	}
+
+	if (!dev->lps_per_blk)
+		pr_info("nvm: lower page programming table missing\n");
 
 	if (grp->mpos & 0x020202)
 		dev->plane_mode = NVM_PLANE_DOUBLE;
···
 
 	if (dev->mt)
 		dev->mt->unregister_mgr(dev);
+
+	kfree(dev->lptbl);
 }
 
 static int nvm_init(struct nvm_dev *dev)

drivers/nvme/host/lightnvm.c

···
 	};
 };
 
+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;
···
 	__le32			mpos;
 	__le32			mccap;
 	__le16			cpar;
-	__u8			reserved[906];
+	__u8			reserved[10];
+	struct nvme_nvm_lp_tbl lptbl;
 } __packed;
 
 struct nvme_nvm_addr_format {
···
 		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;

include/linux/lightnvm.h

···
 	NVM_ID_CAP_CMD_SUSPEND	= 0x2,
 	NVM_ID_CAP_SCRAMBLE	= 0x4,
 	NVM_ID_CAP_ENCRYPT	= 0x8,
+
+	/* Memory types */
+	NVM_ID_FMTYPE_SLC	= 0,
+	NVM_ID_FMTYPE_MLC	= 1,
+};
+
+struct nvm_id_lp_mlc {
+	u16	num_pairs;
+	u8	pairs[886];
+};
+
+struct nvm_id_lp_tbl {
+	__u8	id[8];
+	struct nvm_id_lp_mlc mlc;
 };
 
 struct nvm_id_group {
···
 	u32	mpos;
 	u32	mccap;
 	u16	cpar;
+
+	struct nvm_id_lp_tbl lptbl;
 };
 
 struct nvm_addr_format {
···
 	int sec_per_pl; /* all sectors across planes */
 	int sec_per_blk;
 	int sec_per_lun;
+
+	/* lower page table */
+	int lps_per_blk;
+	int *lptbl;
 
 	unsigned long total_pages;
 	unsigned long total_blocks;