[PATCH v2] mtd: spi-nor: parse SFDP 4-byte Address Instruction Table

[Tudor.Ambarus]

From: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxxxxxx>

Add support for SFDP (JESD216B) 4-byte Address Instruction Table. This
table is optional but when available, we parse it to get the 4-byte
address op codes supported by the memory.
Using these op codes is stateless as opposed to entering the 4-byte
address mode or setting the Base Address Register (BAR).

Flashes that have the 4BAIT table declared can now support
SPINOR_OP_PP_1_1_4_4B and SPINOR_OP_PP_1_4_4_4B opcodes.

Tested on MX25L25673G.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxxxxxx>
[tudor.ambarus@xxxxxxxxxxxxx:
- rework erase and page program logic,
- pass DMA-able buffer to spi_nor_read_sfdp(),
- introduce SPI_NOR_HAS_4BAIT
- various minor updates.]
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
---
v2:
- introduce SPI_NOR_HAS_4BAIT
- use SNOR_F_4B_OPCODES

This patch depends on:
- "mtd: spi-nor: fix selection of uniform erase type in flexible conf"
  which was already applied as a fix
- "mtd: spi-nor: Add the SNOR_F_4B_OPCODES flag" which will be present
  in spi-nor/next

 drivers/mtd/spi-nor/spi-nor.c | 193 +++++++++++++++++++++++++++++++++++++++++-
 include/linux/mtd/spi-nor.h   |   1 +
 2 files changed, 193 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index a9508db58d7f..e77efc153736 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -121,6 +121,7 @@ struct sfdp_parameter_header {
 
 #define SFDP_BFPT_ID		0xff00	/* Basic Flash Parameter Table */
 #define SFDP_SECTOR_MAP_ID	0xff81	/* Sector Map Table */
+#define SFDP_4BAIT_ID		0xff84  /* 4-byte Address Instruction Table */
 
 #define SFDP_SIGNATURE		0x50444653U
 #define SFDP_JESD216_MAJOR	1
@@ -3179,6 +3180,191 @@ static int spi_nor_parse_smpt(struct spi_nor *nor,
 	return ret;
 }
 
+#define SFDP_4BAIT_DWORD_MAX	2
+
+struct sfdp_4bait {
+	/* The hardware capability. */
+	u32		hwcaps;
+
+	/*
+	 * The <supported_bit> bit in DWORD1 of the 4BAIT tells us whether
+	 * the associated 4-byte address op code is supported.
+	 */
+	u32		supported_bit;
+};
+
+/**
+ * spi_nor_parse_4bait() - parse the 4-Byte Address Instruction Table
+ * @nor:		pointer to a 'struct spi_nor'.
+ * @param_header:	pointer to the 'struct sfdp_parameter_header' describing
+ *			the 4-Byte Address Instruction Table length and version.
+ * @params:		pointer to the 'struct spi_nor_flash_parameter' to be.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_parse_4bait(struct spi_nor *nor,
+			       const struct sfdp_parameter_header *param_header,
+			       struct spi_nor_flash_parameter *params)
+{
+	static const struct sfdp_4bait reads[] = {
+		{ SNOR_HWCAPS_READ,		BIT(0) },
+		{ SNOR_HWCAPS_READ_FAST,	BIT(1) },
+		{ SNOR_HWCAPS_READ_1_1_2,	BIT(2) },
+		{ SNOR_HWCAPS_READ_1_2_2,	BIT(3) },
+		{ SNOR_HWCAPS_READ_1_1_4,	BIT(4) },
+		{ SNOR_HWCAPS_READ_1_4_4,	BIT(5) },
+		{ SNOR_HWCAPS_READ_1_1_1_DTR,	BIT(13) },
+		{ SNOR_HWCAPS_READ_1_2_2_DTR,	BIT(14) },
+		{ SNOR_HWCAPS_READ_1_4_4_DTR,	BIT(15) },
+	};
+	static const struct sfdp_4bait programs[] = {
+		{ SNOR_HWCAPS_PP,		BIT(6) },
+		{ SNOR_HWCAPS_PP_1_1_4,		BIT(7) },
+		{ SNOR_HWCAPS_PP_1_4_4,		BIT(8) },
+	};
+	static const struct sfdp_4bait erases[SNOR_ERASE_TYPE_MAX] = {
+		{ 0u /* not used */,		BIT(9) },
+		{ 0u /* not used */,		BIT(10) },
+		{ 0u /* not used */,		BIT(11) },
+		{ 0u /* not used */,		BIT(12) },
+	};
+	struct spi_nor_pp_command *params_pp = params->page_programs;
+	struct spi_nor_erase_map *map = &nor->erase_map;
+	struct spi_nor_erase_type *erase_type = map->erase_type;
+	u32 *dwords;
+	size_t len;
+	u32 addr, discard_hwcaps, read_hwcaps, pp_hwcaps, erase_mask;
+	int i, ret;
+
+	if (param_header->major != SFDP_JESD216_MAJOR ||
+	    param_header->length < SFDP_4BAIT_DWORD_MAX)
+		return -EINVAL;
+
+	/* Read the 4-byte Address Instruction Table. */
+	len = sizeof(*dwords) * SFDP_4BAIT_DWORD_MAX;
+
+	/* Use a kmalloc'ed bounce buffer to guarantee it is DMA-able. */
+	dwords = kmalloc(len, GFP_KERNEL);
+	if (!dwords)
+		return -ENOMEM;
+
+	addr = SFDP_PARAM_HEADER_PTP(param_header);
+	ret = spi_nor_read_sfdp(nor, addr, len, dwords);
+	if (ret)
+		return ret;
+
+	/* Fix endianness of the 4BAIT DWORDs. */
+	for (i = 0; i < SFDP_4BAIT_DWORD_MAX; i++)
+		dwords[i] = le32_to_cpu(dwords[i]);
+
+	/*
+	 * Compute the subset of (Fast) Read commands for which the 4-byte
+	 * version is supported.
+	 */
+	discard_hwcaps = 0;
+	read_hwcaps = 0;
+	for (i = 0; i < ARRAY_SIZE(reads); i++) {
+		const struct sfdp_4bait *read = &reads[i];
+
+		discard_hwcaps |= read->hwcaps;
+		if ((params->hwcaps.mask & read->hwcaps) &&
+		    (dwords[0] & read->supported_bit))
+			read_hwcaps |= read->hwcaps;
+	}
+
+	/*
+	 * Compute the subset of Page Program commands for which the 4-byte
+	 * version is supported.
+	 */
+	pp_hwcaps = 0;
+	for (i = 0; i < ARRAY_SIZE(programs); i++) {
+		const struct sfdp_4bait *program = &programs[i];
+
+		/*
+		 * The 4 Byte Address Instruction (Optional) Table is the only
+		 * SFDP table that indicates support for Page Program Commands.
+		 * Bypass the params->hwcaps.mask and consider 4BAIT the biggest
+		 * authority for specifying Page Program support.
+		 */
+		discard_hwcaps |= program->hwcaps;
+		if (dwords[0] & program->supported_bit)
+			pp_hwcaps |= program->hwcaps;
+	}
+
+	/*
+	 * Compute the subset of Sector Erase commands for which the 4-byte
+	 * version is supported.
+	 */
+	erase_mask = 0;
+	for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++) {
+		const struct sfdp_4bait *erase = &erases[i];
+
+		if (dwords[0] & erase->supported_bit)
+			erase_mask |= BIT(i);
+	}
+
+	/* Replicate the sort done for the map's erase types in BFPT. */
+	erase_mask = spi_nor_sort_erase_mask(map, erase_mask);
+
+	/*
+	 * We need at least one 4-byte op code per read, program and erase
+	 * operation; the .read(), .write() and .erase() hooks share the
+	 * nor->addr_width value.
+	 */
+	if (!read_hwcaps || !pp_hwcaps || !erase_mask)
+		goto out;
+
+	/*
+	 * Discard all operations from the 4-byte instruction set which are
+	 * not supported by this memory.
+	 */
+	params->hwcaps.mask &= ~discard_hwcaps;
+	params->hwcaps.mask |= (read_hwcaps | pp_hwcaps);
+
+	/* Use the 4-byte address instruction set. */
+	for (i = 0; i < SNOR_CMD_READ_MAX; i++) {
+		struct spi_nor_read_command *read_cmd = &params->reads[i];
+
+		read_cmd->opcode = spi_nor_convert_3to4_read(read_cmd->opcode);
+	}
+
+	/* 4BAIT is the only SFDP table that indicates page program support. */
+	if (pp_hwcaps & SNOR_HWCAPS_PP)
+		spi_nor_set_pp_settings(&params_pp[SNOR_CMD_PP],
+					SPINOR_OP_PP_4B, SNOR_PROTO_1_1_1);
+	if (pp_hwcaps & SNOR_HWCAPS_PP_1_1_4)
+		spi_nor_set_pp_settings(&params_pp[SNOR_CMD_PP_1_1_4],
+					SPINOR_OP_PP_1_1_4_4B,
+					SNOR_PROTO_1_1_4);
+	if (pp_hwcaps & SNOR_HWCAPS_PP_1_4_4)
+		spi_nor_set_pp_settings(&params_pp[SNOR_CMD_PP_1_4_4],
+					SPINOR_OP_PP_1_4_4_4B,
+					SNOR_PROTO_1_4_4);
+
+	for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++) {
+		if (erase_mask & BIT(i))
+			erase_type[i].opcode = (dwords[1] >>
+						erase_type[i].idx * 8) & 0xFF;
+		else
+			spi_nor_set_erase_type(&erase_type[i], 0u, 0xFF);
+	}
+
+	/*
+	 * We set SNOR_F_HAS_4BAIT in order to skip spi_nor_set_4byte_opcodes()
+	 * later because we already did the conversion to 4byte opcodes. Also,
+	 * this latest function implements a legacy quirk for the erase size of
+	 * Spansion memory. However this quirk is no longer needed with new
+	 * SFDP compliant memories.
+	 */
+	nor->addr_width = 4;
+	nor->flags |= SNOR_F_4B_OPCODES | SNOR_F_HAS_4BAIT;
+
+	/* fall through */
+out:
+	kfree(dwords);
+	return ret;
+}
+
 /**
  * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
  * @nor:		pointer to a 'struct spi_nor'
@@ -3276,6 +3462,10 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
 			err = spi_nor_parse_smpt(nor, param_header);
 			break;
 
+		case SFDP_4BAIT_ID:
+			err = spi_nor_parse_4bait(nor, param_header, params);
+			break;
+
 		default:
 			break;
 		}
@@ -3857,7 +4047,8 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	    (JEDEC_MFR(info) == SNOR_MFR_SPANSION && mtd->size > SZ_16M))
 		nor->flags |= SNOR_F_4B_OPCODES;
 
-	if (nor->addr_width == 4 && nor->flags & SNOR_F_4B_OPCODES)
+	if (nor->addr_width == 4 && nor->flags & SNOR_F_4B_OPCODES &&
+	    !(nor->flags & SNOR_F_HAS_4BAIT))
 		spi_nor_set_4byte_opcodes(nor);
 
 	if (nor->addr_width > SPI_NOR_MAX_ADDR_WIDTH) {
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 5f177aa39f68..fa2d89e38e40 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -234,6 +234,7 @@ enum spi_nor_option_flags {
 	SNOR_F_USE_CLSR		= BIT(5),
 	SNOR_F_BROKEN_RESET	= BIT(6),
 	SNOR_F_4B_OPCODES	= BIT(7),
+	SNOR_F_HAS_4BAIT	= BIT(8),
 };
 
 /**
-- 
2.9.4