Date:   Mon, 26 Jun 2017 15:10:00 +0200
From:   Cyrille Pitchen <cyrille.pitchen@...rochip.com>
To:     <marek.vasut@...il.com>
CC:     <computersforpeace@...il.com>,
        <boris.brezillon@...e-electrons.com>, <richard@....at>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        Cyrille Pitchen <cyrille.pitchen@...rochip.com>
Subject: [PATCH v3 2/2] mtd: spi-nor: parse Serial Flash Discoverable Parameters (SFDP) tables

This patch adds support to the JESD216 rev B standard and parses the SFDP
tables to dynamically initialize the 'struct spi_nor_flash_parameter'.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...rochip.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 775 +++++++++++++++++++++++++++++++++++++++++-
 include/linux/mtd/spi-nor.h   |   6 +
 2 files changed, 768 insertions(+), 13 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 040ab5d7ac05..dac789ff70ea 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -17,6 +17,7 @@
 #include <linux/mutex.h>
 #include <linux/math64.h>
 #include <linux/sizes.h>
+#include <linux/slab.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/of_platform.h>
@@ -86,6 +87,7 @@ struct flash_info {
 					 * to support memory size above 128Mib.
 					 */
 #define NO_CHIP_ERASE		BIT(12) /* Chip does not support chip erase */
+#define SPI_NOR_SKIP_SFDP	BIT(13)	/* Skip parsing of SFDP tables */
 };
 
 #define JEDEC_MFR(info)	((info)->id[0])
@@ -1378,6 +1380,16 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 	return ret;
 }
 
+/**
+ * macronix_quad_enable() - set QE bit in Status Register.
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Set the Quad Enable (QE) bit in the Status Register.
+ *
+ * bit 6 of the Status Register is the QE bit for Macronix like QSPI memories.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int macronix_quad_enable(struct spi_nor *nor)
 {
 	int ret, val;
@@ -1411,22 +1423,13 @@ static int macronix_quad_enable(struct spi_nor *nor)
  * second byte will be written to the configuration register.
  * Return negative if error occurred.
  */
-static int write_sr_cr(struct spi_nor *nor, u16 val)
-{
-	nor->cmd_buf[0] = val & 0xff;
-	nor->cmd_buf[1] = (val >> 8);
-
-	return nor->write_reg(nor, SPINOR_OP_WRSR, nor->cmd_buf, 2);
-}
-
-static int spansion_quad_enable(struct spi_nor *nor)
+static int write_sr_cr(struct spi_nor *nor, u8 *sr_cr)
 {
 	int ret;
-	int quad_en = CR_QUAD_EN_SPAN << 8;
 
 	write_enable(nor);
 
-	ret = write_sr_cr(nor, quad_en);
+	ret = nor->write_reg(nor, SPINOR_OP_WRSR, sr_cr, 2);
 	if (ret < 0) {
 		dev_err(nor->dev,
 			"error while writing configuration register\n");
@@ -1440,6 +1443,41 @@ static int spansion_quad_enable(struct spi_nor *nor)
 		return ret;
 	}
 
+	return 0;
+}
+
+/**
+ * spansion_quad_enable() - set QE bit in Configuraiton Register.
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Set the Quad Enable (QE) bit in the Configuration Register.
+ * This function is kept for legacy purpose because it has been used for a
+ * long time without anybody complaining but it should be considered as
+ * deprecated and maybe buggy.
+ * First, this function doesn't care about the previous values of the Status
+ * and Configuration Registers when it sets the QE bit (bit 1) in the
+ * Configuration Register: all other bits are cleared, which may have unwanted
+ * side effects like removing some block protections.
+ * Secondly, it uses the Read Configuration Register (35h) instruction though
+ * some very old and few memories don't support this instruction. If a pull-up
+ * resistor is present on the MISO/IO1 line, we might still be able to pass the
+ * "read back" test because the QSPI memory doesn't recognize the command,
+ * so leaves the MISO/IO1 line state unchanged, hence read_cr() returns 0xFF.
+ *
+ * bit 1 of the Configuration Register is the QE bit for Spansion like QSPI
+ * memories.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spansion_quad_enable(struct spi_nor *nor)
+{
+	u8 sr_cr[2] = {0, CR_QUAD_EN_SPAN};
+	int ret;
+
+	ret = write_sr_cr(nor, sr_cr);
+	if (ret)
+		return ret;
+
 	/* read back and check it */
 	ret = read_cr(nor);
 	if (!(ret > 0 && (ret & CR_QUAD_EN_SPAN))) {
@@ -1450,6 +1488,140 @@ static int spansion_quad_enable(struct spi_nor *nor)
 	return 0;
 }
 
+/**
+ * spansion_no_read_cr_quad_enable() - set QE bit in Configuration Register.
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Set the Quad Enable (QE) bit in the Configuration Register.
+ * This function should be used with QSPI memories not supporting the Read
+ * Configuration Register (35h) instruction.
+ *
+ * bit 1 of the Configuration Register is the QE bit for Spansion like QSPI
+ * memories.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spansion_no_read_cr_quad_enable(struct spi_nor *nor)
+{
+	u8 sr_cr[2];
+	int ret;
+
+	/* Keep the current value of the Status Register. */
+	ret = read_sr(nor);
+	if (ret < 0) {
+		dev_err(nor->dev, "error while reading status register\n");
+		return -EINVAL;
+	}
+	sr_cr[0] = ret;
+	sr_cr[1] = CR_QUAD_EN_SPAN;
+
+	return write_sr_cr(nor, sr_cr);
+}
+
+/**
+ * spansion_read_cr_quad_enable() - set QE bit in Configuration Register.
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Set the Quad Enable (QE) bit in the Configuration Register.
+ * This function should be used with QSPI memories supporting the Read
+ * Configuration Register (35h) instruction.
+ *
+ * bit 1 of the Configuration Register is the QE bit for Spansion like QSPI
+ * memories.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spansion_read_cr_quad_enable(struct spi_nor *nor)
+{
+	struct device *dev = nor->dev;
+	u8 sr_cr[2];
+	int ret;
+
+	/* Check current Quad Enable bit value. */
+	ret = read_cr(nor);
+	if (ret < 0) {
+		dev_err(dev, "error while reading configuration register\n");
+		return -EINVAL;
+	}
+
+	if (ret & CR_QUAD_EN_SPAN)
+		return 0;
+
+	sr_cr[1] = ret | CR_QUAD_EN_SPAN;
+
+	/* Keep the current value of the Status Register. */
+	ret = read_sr(nor);
+	if (ret < 0) {
+		dev_err(dev, "error while reading status register\n");
+		return -EINVAL;
+	}
+	sr_cr[0] = ret;
+
+	ret = write_sr_cr(nor, sr_cr);
+	if (ret)
+		return ret;
+
+	/* Read back and check it. */
+	ret = read_cr(nor);
+	if (!(ret > 0 && (ret & CR_QUAD_EN_SPAN))) {
+		dev_err(nor->dev, "Spansion Quad bit not set\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * sr2_bit7_quad_enable() - set QE bit in Status Register 2.
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Set the Quad Enable (QE) bit in the Status Register 2.
+ *
+ * This is one of the procedures to set the QE bit described in the SFDP
+ * (JESD216 rev B) specification but no manufacturer using this procedure has
+ * been identified yet, hence the name of the function.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int sr2_bit7_quad_enable(struct spi_nor *nor)
+{
+	u8 sr2;
+	int ret;
+
+	/* Check current Quad Enable bit value. */
+	ret = nor->read_reg(nor, SPINOR_OP_RDSR2, &sr2, 1);
+	if (ret)
+		return ret;
+	if (sr2 & SR2_QUAD_EN_BIT7)
+		return 0;
+
+	/* Update the Quad Enable bit. */
+	sr2 |= SR2_QUAD_EN_BIT7;
+
+	write_enable(nor);
+
+	ret = nor->write_reg(nor, SPINOR_OP_WRSR2, &sr2, 1);
+	if (ret < 0) {
+		dev_err(nor->dev, "error while writing status register 2\n");
+		return -EINVAL;
+	}
+
+	ret = spi_nor_wait_till_ready(nor);
+	if (ret < 0) {
+		dev_err(nor->dev, "timeout while writing status register 2\n");
+		return ret;
+	}
+
+	/* Read back and check it. */
+	ret = nor->read_reg(nor, SPINOR_OP_RDSR2, &sr2, 1);
+	if (!(ret > 0 && (sr2 & SR2_QUAD_EN_BIT7))) {
+		dev_err(nor->dev, "SR2 Quad bit not set\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int spi_nor_check(struct spi_nor *nor)
 {
 	if (!nor->dev || !nor->read || !nor->write ||
@@ -1589,6 +1761,560 @@ spi_nor_set_pp_settings(struct spi_nor_pp_command *pp,
 	pp->proto = proto;
 }
 
+/*
+ * Serial Flash Discoverable Parameters (SFDP) parsing.
+ */
+
+/**
+ * spi_nor_read_sfdp() - read Serial Flash Discoverable Parameters.
+ * @nor:	pointer to a 'struct spi_nor'
+ * @addr:	offset in the SFDP area to start reading data from
+ * @len:	number of bytes to read
+ * @buf:	buffer where the SFDP data are copied into
+ *
+ * Whatever the actual numbers of bytes for address and dummy cycles are
+ * for (Fast) Read commands, the Read SFDP (5Ah) instruction is always
+ * followed by a 3-byte address and 8 dummy clock cycles.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_read_sfdp(struct spi_nor *nor, u32 addr,
+			     size_t len, void *buf)
+{
+	u8 addr_width, read_opcode, read_dummy;
+	int ret;
+
+	read_opcode = nor->read_opcode;
+	addr_width = nor->addr_width;
+	read_dummy = nor->read_dummy;
+
+	nor->read_opcode = SPINOR_OP_RDSFDP;
+	nor->addr_width = 3;
+	nor->read_dummy = 8;
+
+	while (len) {
+		ret = nor->read(nor, addr, len, (u8 *)buf);
+		if (!ret || ret > len) {
+			ret = -EIO;
+			goto read_err;
+		}
+		if (ret < 0)
+			goto read_err;
+
+		buf += ret;
+		addr += ret;
+		len -= ret;
+	}
+	ret = 0;
+
+read_err:
+	nor->read_opcode = read_opcode;
+	nor->addr_width = addr_width;
+	nor->read_dummy = read_dummy;
+
+	return ret;
+}
+
+struct sfdp_parameter_header {
+	u8		id_lsb;
+	u8		minor;
+	u8		major;
+	u8		length; /* in double words */
+	u8		parameter_table_pointer[3]; /* byte address */
+	u8		id_msb;
+};
+
+#define SFDP_PARAM_HEADER_ID(p)	(((p)->id_msb << 8) | (p)->id_lsb)
+#define SFDP_PARAM_HEADER_PTP(p) \
+	(((p)->parameter_table_pointer[2] << 16) | \
+	 ((p)->parameter_table_pointer[1] <<  8) | \
+	 ((p)->parameter_table_pointer[0] <<  0))
+
+#define SFDP_BFPT_ID		0xff00	/* Basic Flash Parameter Table */
+#define SFDP_SECTOR_MAP_ID	0xff81	/* Sector Map Table */
+
+#define SFDP_SIGNATURE		0x50444653U
+#define SFDP_JESD216_MAJOR	1
+#define SFDP_JESD216_MINOR	0
+#define SFDP_JESD216A_MINOR	5
+#define SFDP_JESD216B_MINOR	6
+
+struct sfdp_header {
+	u32		signature; /* Ox50444653U <=> "SFDP" */
+	u8		minor;
+	u8		major;
+	u8		nph; /* 0-base number of parameter headers */
+	u8		unused;
+
+	/* Basic Flash Parameter Table. */
+	struct sfdp_parameter_header	bfpt_header;
+};
+
+/* Basic Flash Parameter Table */
+
+/*
+ * JESD216 rev B defines a Basic Flash Parameter Table of 16 DWORDs.
+ * They are indexed from 1 but C arrays are indexed from 0.
+ */
+#define BFPT_DWORD(i)		((i) - 1)
+#define BFPT_DWORD_MAX		16
+
+/* The first version of JESB216 defined only 9 DWORDs. */
+#define BFPT_DWORD_MAX_JESD216			9
+
+/* 1st DWORD. */
+#define BFPT_DWORD1_FAST_READ_1_1_2		BIT(16)
+#define BFPT_DWORD1_ADDRESS_BYTES_MASK		GENMASK(18, 17)
+#define BFPT_DWORD1_ADDRESS_BYTES_3_ONLY	(0x0UL << 17)
+#define BFPT_DWORD1_ADDRESS_BYTES_3_OR_4	(0x1UL << 17)
+#define BFPT_DWORD1_ADDRESS_BYTES_4_ONLY	(0x2UL << 17)
+#define BFPT_DWORD1_DTR				BIT(19)
+#define BFPT_DWORD1_FAST_READ_1_2_2		BIT(20)
+#define BFPT_DWORD1_FAST_READ_1_4_4		BIT(21)
+#define BFPT_DWORD1_FAST_READ_1_1_4		BIT(22)
+
+/* 5th DWORD. */
+#define BFPT_DWORD5_FAST_READ_2_2_2		BIT(0)
+#define BFPT_DWORD5_FAST_READ_4_4_4		BIT(4)
+
+/* 11th DWORD. */
+#define BFPT_DWORD11_PAGE_SIZE_SHIFT		4
+#define BFPT_DWORD11_PAGE_SIZE_MASK		GENMASK(7, 4)
+
+/* 15th DWORD. */
+
+/*
+ * (from JESD216 rev B)
+ * Quad Enable Requirements (QER):
+ * - 000b: Device does not have a QE bit. Device detects 1-1-4 and 1-4-4
+ *         reads based on instruction. DQ3/HOLD# functions are hold during
+ *         instruction phase.
+ * - 001b: QE is bit 1 of status register 2. It is set via Write Status with
+ *         two data bytes where bit 1 of the second byte is one.
+ *         [...]
+ *         Writing only one byte to the status register has the side-effect of
+ *         clearing status register 2, including the QE bit. The 100b code is
+ *         used if writing one byte to the status register does not modify
+ *         status register 2.
+ * - 010b: QE is bit 6 of status register 1. It is set via Write Status with
+ *         one data byte where bit 6 is one.
+ *         [...]
+ * - 011b: QE is bit 7 of status register 2. It is set via Write status
+ *         register 2 instruction 3Eh with one data byte where bit 7 is one.
+ *         [...]
+ *         The status register 2 is read using instruction 3Fh.
+ * - 100b: QE is bit 1 of status register 2. It is set via Write Status with
+ *         two data bytes where bit 1 of the second byte is one.
+ *         [...]
+ *         In contrast to the 001b code, writing one byte to the status
+ *         register does not modify status register 2.
+ * - 101b: QE is bit 1 of status register 2. Status register 1 is read using
+ *         Read Status instruction 05h. Status register2 is read using
+ *         instruction 35h. QE is set via Writ Status instruction 01h with
+ *         two data bytes where bit 1 of the second byte is one.
+ *         [...]
+ */
+#define BFPT_DWORD15_QER_MASK			GENMASK(22, 20)
+#define BFPT_DWORD15_QER_NONE			(0x0UL << 20) /* Micron */
+#define BFPT_DWORD15_QER_SR2_BIT1_BUGGY		(0x1UL << 20)
+#define BFPT_DWORD15_QER_SR1_BIT6		(0x2UL << 20) /* Macronix */
+#define BFPT_DWORD15_QER_SR2_BIT7		(0x3UL << 20)
+#define BFPT_DWORD15_QER_SR2_BIT1_NO_RD		(0x4UL << 20)
+#define BFPT_DWORD15_QER_SR2_BIT1		(0x5UL << 20) /* Spansion */
+
+struct sfdp_bfpt {
+	u32	dwords[BFPT_DWORD_MAX];
+};
+
+/* Fast Read settings. */
+
+static inline void
+spi_nor_set_read_settings_from_bfpt(struct spi_nor_read_command *read,
+				    u16 half,
+				    enum spi_nor_protocol proto)
+{
+	read->num_mode_clocks = (half >> 5) & 0x07;
+	read->num_wait_states = (half >> 0) & 0x1f;
+	read->opcode = (half >> 8) & 0xff;
+	read->proto = proto;
+}
+
+struct sfdp_bfpt_read {
+	/* The Fast Read x-y-z hardware capability in params->hwcaps.mask. */
+	u32			hwcaps;
+
+	/*
+	 * The <supported_bit> bit in <supported_dword> BFPT DWORD tells us
+	 * whether the Fast Read x-y-z command is supported.
+	 */
+	u32			supported_dword;
+	u32			supported_bit;
+
+	/*
+	 * The half-word at offset <setting_shift> in <setting_dword> BFPT DWORD
+	 * encodes the op code, the number of mode clocks and the number of wait
+	 * states to be used by Fast Read x-y-z command.
+	 */
+	u32			settings_dword;
+	u32			settings_shift;
+
+	/* The SPI protocol for this Fast Read x-y-z command. */
+	enum spi_nor_protocol	proto;
+};
+
+static const struct sfdp_bfpt_read sfdp_bfpt_reads[] = {
+	/* Fast Read 1-1-2 */
+	{
+		SNOR_HWCAPS_READ_1_1_2,
+		BFPT_DWORD(1), BIT(16),	/* Supported bit */
+		BFPT_DWORD(4), 0,	/* Settings */
+		SNOR_PROTO_1_1_2,
+	},
+
+	/* Fast Read 1-2-2 */
+	{
+		SNOR_HWCAPS_READ_1_2_2,
+		BFPT_DWORD(1), BIT(20),	/* Supported bit */
+		BFPT_DWORD(4), 16,	/* Settings */
+		SNOR_PROTO_1_2_2,
+	},
+
+	/* Fast Read 2-2-2 */
+	{
+		SNOR_HWCAPS_READ_2_2_2,
+		BFPT_DWORD(5),  BIT(0),	/* Supported bit */
+		BFPT_DWORD(6), 16,	/* Settings */
+		SNOR_PROTO_2_2_2,
+	},
+
+	/* Fast Read 1-1-4 */
+	{
+		SNOR_HWCAPS_READ_1_1_4,
+		BFPT_DWORD(1), BIT(22),	/* Supported bit */
+		BFPT_DWORD(3), 16,	/* Settings */
+		SNOR_PROTO_1_1_4,
+	},
+
+	/* Fast Read 1-4-4 */
+	{
+		SNOR_HWCAPS_READ_1_4_4,
+		BFPT_DWORD(1), BIT(21),	/* Supported bit */
+		BFPT_DWORD(3), 0,	/* Settings */
+		SNOR_PROTO_1_4_4,
+	},
+
+	/* Fast Read 4-4-4 */
+	{
+		SNOR_HWCAPS_READ_4_4_4,
+		BFPT_DWORD(5), BIT(4),	/* Supported bit */
+		BFPT_DWORD(7), 16,	/* Settings */
+		SNOR_PROTO_4_4_4,
+	},
+};
+
+struct sfdp_bfpt_erase {
+	/*
+	 * The half-word at offset <shift> in DWORD <dwoard> encodes the
+	 * op code and erase sector size to be used by Sector Erase commands.
+	 */
+	u32			dword;
+	u32			shift;
+};
+
+static const struct sfdp_bfpt_erase sfdp_bfpt_erases[] = {
+	/* Erase Type 1 in DWORD8 bits[15:0] */
+	{BFPT_DWORD(8), 0},
+
+	/* Erase Type 2 in DWORD8 bits[31:16] */
+	{BFPT_DWORD(8), 16},
+
+	/* Erase Type 3 in DWORD9 bits[15:0] */
+	{BFPT_DWORD(9), 0},
+
+	/* Erase Type 4 in DWORD9 bits[31:16] */
+	{BFPT_DWORD(9), 16},
+};
+
+static int spi_nor_hwcaps_read2cmd(u32 hwcaps);
+
+/**
+ * spi_nor_parse_bfpt() - read and parse the Basic Flash Parameter Table.
+ * @nor:		pointer to a 'struct spi_nor'
+ * @bfpt_header:	pointer to the 'struct sfdp_parameter_header' describing
+ *			the Basic Flash Parameter Table length and version
+ * @params:		pointer to the 'struct spi_nor_flash_parameter' to be
+ *			filled
+ *
+ * The Basic Flash Parameter Table is the main and only mandatory table as
+ * defined by the SFDP (JESD216) specification.
+ * It provides us with the total size (memory density) of the data array and
+ * the number of address bytes for Fast Read, Page Program and Sector Erase
+ * commands.
+ * For Fast READ commands, it also gives the number of mode clock cycles and
+ * wait states (regrouped in the number of dummy clock cycles) for each
+ * supported instruction op code.
+ * For Page Program, the page size is now available since JESD216 rev A, however
+ * the supported instruction op codes are still not provided.
+ * For Sector Erase commands, this table stores the supported instruction op
+ * codes and the associated sector sizes.
+ * Finally, the Quad Enable Requirements (QER) are also available since JESD216
+ * rev A. The QER bits encode the manufacturer dependent procedure to be
+ * executed to set the Quad Enable (QE) bit in some internal register of the
+ * Quad SPI memory. Indeed the QE bit, when it exists, must be set before
+ * sending any Quad SPI command to the memory. Actually, setting the QE bit
+ * tells the memory to reassign its WP# and HOLD#/RESET# pins to functions IO2
+ * and IO3 hence enabling 4 (Quad) I/O lines.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_parse_bfpt(struct spi_nor *nor,
+			      const struct sfdp_parameter_header *bfpt_header,
+			      struct spi_nor_flash_parameter *params)
+{
+	struct mtd_info *mtd = &nor->mtd;
+	struct sfdp_bfpt bfpt;
+	size_t len;
+	int i, cmd, err;
+	u32 addr;
+	u16 half;
+
+	/* JESD216 Basic Flash Parameter Table length is at least 9 DWORDs. */
+	if (bfpt_header->length < BFPT_DWORD_MAX_JESD216)
+		return -EINVAL;
+
+	/* Read the Basic Flash Parameter Table. */
+	len = min_t(size_t, sizeof(bfpt),
+		    bfpt_header->length * sizeof(u32));
+	addr = SFDP_PARAM_HEADER_PTP(bfpt_header);
+	memset(&bfpt, 0, sizeof(bfpt));
+	err = spi_nor_read_sfdp(nor,  addr, len, &bfpt);
+	if (err < 0)
+		return err;
+
+	/* Fix endianness of the BFPT DWORDs. */
+	for (i = 0; i < BFPT_DWORD_MAX; i++)
+		bfpt.dwords[i] = le32_to_cpu(bfpt.dwords[i]);
+
+	/* Number of address bytes. */
+	switch (bfpt.dwords[BFPT_DWORD(1)] & BFPT_DWORD1_ADDRESS_BYTES_MASK) {
+	case BFPT_DWORD1_ADDRESS_BYTES_3_ONLY:
+		nor->addr_width = 3;
+		break;
+
+	case BFPT_DWORD1_ADDRESS_BYTES_4_ONLY:
+		nor->addr_width = 4;
+		break;
+
+	default:
+		break;
+	}
+
+	/* Flash Memory Density (in bits). */
+	params->size = bfpt.dwords[BFPT_DWORD(2)];
+	if (params->size & BIT(31)) {
+		params->size &= ~BIT(31);
+		params->size = 1ULL << params->size;
+	} else {
+		params->size++;
+	}
+	params->size >>= 3; /* Convert to bytes. */
+
+	/* Fast Read settings. */
+	for (i = 0; i < ARRAY_SIZE(sfdp_bfpt_reads); i++) {
+		const struct sfdp_bfpt_read *rd = &sfdp_bfpt_reads[i];
+		struct spi_nor_read_command *read;
+
+		if (!(bfpt.dwords[rd->supported_dword] & rd->supported_bit)) {
+			params->hwcaps.mask &= ~rd->hwcaps;
+			continue;
+		}
+
+		params->hwcaps.mask |= rd->hwcaps;
+		cmd = spi_nor_hwcaps_read2cmd(rd->hwcaps);
+		read = &params->reads[cmd];
+		half = bfpt.dwords[rd->settings_dword] >> rd->settings_shift;
+		spi_nor_set_read_settings_from_bfpt(read, half, rd->proto);
+	}
+
+	/* Sector Erase settings. */
+	for (i = 0; i < ARRAY_SIZE(sfdp_bfpt_erases); i++) {
+		const struct sfdp_bfpt_erase *er = &sfdp_bfpt_erases[i];
+		u32 erasesize;
+		u8 opcode;
+
+		half = bfpt.dwords[er->dword] >> er->shift;
+		erasesize = half & 0xff;
+
+		/* erasesize == 0 means this Erase Type is not supported. */
+		if (!erasesize)
+			continue;
+
+		erasesize = 1U << erasesize;
+		opcode = (half >> 8) & 0xff;
+#ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
+		if (erasesize == SZ_4K) {
+			nor->erase_opcode = opcode;
+			mtd->erasesize = erasesize;
+			break;
+		}
+#endif
+		if (!mtd->erasesize || mtd->erasesize < erasesize) {
+			nor->erase_opcode = opcode;
+			mtd->erasesize = erasesize;
+		}
+	}
+
+	/* Stop here if not JESD216 rev A or later. */
+	if (bfpt_header->length < BFPT_DWORD_MAX)
+		return 0;
+
+	/* Page size: this field specifies 'N' so the page size = 2^N bytes. */
+	params->page_size = bfpt.dwords[BFPT_DWORD(11)];
+	params->page_size &= BFPT_DWORD11_PAGE_SIZE_MASK;
+	params->page_size >>= BFPT_DWORD11_PAGE_SIZE_SHIFT;
+	params->page_size = 1U << params->page_size;
+
+	/* Quad Enable Requirements. */
+	switch (bfpt.dwords[BFPT_DWORD(15)] & BFPT_DWORD15_QER_MASK) {
+	case BFPT_DWORD15_QER_NONE:
+		params->quad_enable = NULL;
+		break;
+
+	case BFPT_DWORD15_QER_SR2_BIT1_BUGGY:
+	case BFPT_DWORD15_QER_SR2_BIT1_NO_RD:
+		params->quad_enable = spansion_no_read_cr_quad_enable;
+		break;
+
+	case BFPT_DWORD15_QER_SR1_BIT6:
+		params->quad_enable = macronix_quad_enable;
+		break;
+
+	case BFPT_DWORD15_QER_SR2_BIT7:
+		params->quad_enable = sr2_bit7_quad_enable;
+		break;
+
+	case BFPT_DWORD15_QER_SR2_BIT1:
+		params->quad_enable = spansion_read_cr_quad_enable;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
+ * @nor:		pointer to a 'struct spi_nor'
+ * @params:		pointer to the 'struct spi_nor_flash_parameter' to be
+ *			filled
+ *
+ * The Serial Flash Discoverable Parameters are described by the JEDEC JESD216
+ * specification. This is a standard which tends to supported by almost all
+ * (Q)SPI memory manufacturers. Those hard-coded tables allow us to learn at
+ * runtime the main parameters needed to perform basic SPI flash operations such
+ * as Fast Read, Page Program or Sector Erase commands.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_parse_sfdp(struct spi_nor *nor,
+			      struct spi_nor_flash_parameter *params)
+{
+	const struct sfdp_parameter_header *param_header, *bfpt_header;
+	struct sfdp_parameter_header *param_headers = NULL;
+	struct sfdp_header header;
+	struct device *dev = nor->dev;
+	size_t psize;
+	int i, err;
+
+	/* Get the SFDP header. */
+	err = spi_nor_read_sfdp(nor, 0, sizeof(header), &header);
+	if (err < 0)
+		return err;
+
+	/* Check the SFDP header version. */
+	if (le32_to_cpu(header.signature) != SFDP_SIGNATURE ||
+	    header.major != SFDP_JESD216_MAJOR ||
+	    header.minor < SFDP_JESD216_MINOR)
+		return -EINVAL;
+
+	/*
+	 * Verify that the first and only mandatory parameter header is a
+	 * Basic Flash Parameter Table header as specified in JESD216.
+	 */
+	bfpt_header = &header.bfpt_header;
+	if (SFDP_PARAM_HEADER_ID(bfpt_header) != SFDP_BFPT_ID ||
+	    bfpt_header->major != SFDP_JESD216_MAJOR)
+		return -EINVAL;
+
+	/*
+	 * Allocate memory then read all parameter headers with a single
+	 * Read SFDP command. These parameter headers will actually be parsed
+	 * twice: a first time to get the latest revision of the basic flash
+	 * parameter table, then a second time to handle the supported optional
+	 * tables.
+	 * Hence we read the parameter headers once for all to reduce the
+	 * processing time. Also we use kmalloc() instead of devm_kmalloc()
+	 * because we don't need to keep these parameter headers: the allocated
+	 * memory is always released with kfree() before exiting this function.
+	 */
+	if (header.nph) {
+		psize = header.nph * sizeof(*param_headers);
+
+		param_headers = kmalloc(psize, GFP_KERNEL);
+		if (!param_headers)
+			return -ENOMEM;
+
+		err = spi_nor_read_sfdp(nor, sizeof(header),
+					psize, param_headers);
+		if (err < 0) {
+			dev_err(dev, "failed to read SFDP parameter headers\n");
+			goto exit;
+		}
+	}
+
+	/*
+	 * Check other parameter headers to get the latest revision of
+	 * the basic flash parameter table.
+	 */
+	for (i = 0; i < header.nph; i++) {
+		param_header = &param_headers[i];
+
+		if (SFDP_PARAM_HEADER_ID(param_header) == SFDP_BFPT_ID &&
+		    param_header->major == SFDP_JESD216_MAJOR &&
+		    (param_header->minor > bfpt_header->minor ||
+		     (param_header->minor == bfpt_header->minor &&
+		      param_header->length > bfpt_header->length)))
+			bfpt_header = param_header;
+	}
+
+	err = spi_nor_parse_bfpt(nor, bfpt_header, params);
+	if (err)
+		goto exit;
+
+	/* Parse other parameter headers. */
+	for (i = 0; i < header.nph; i++) {
+		param_header = &param_headers[i];
+
+		switch (SFDP_PARAM_HEADER_ID(param_header)) {
+		case SFDP_SECTOR_MAP_ID:
+			dev_info(dev, "non-uniform erase sector maps are not supported yet.\n");
+			break;
+
+		default:
+			break;
+		}
+
+		if (err)
+			goto exit;
+	}
+
+exit:
+	kfree(param_headers);
+	return err;
+}
+
 static int spi_nor_init_params(struct spi_nor *nor,
 			       const struct flash_info *info,
 			       struct spi_nor_flash_parameter *params)
@@ -1644,11 +2370,28 @@ static int spi_nor_init_params(struct spi_nor *nor,
 			break;
 
 		default:
+			/* Kept only for backward compatibility purpose. */
 			params->quad_enable = spansion_quad_enable;
 			break;
 		}
 	}
 
+	/* Override the parameters with data read from SFDP tables. */
+	nor->addr_width = 0;
+	nor->mtd.erasesize = 0;
+	if ((info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)) &&
+	    !(info->flags & SPI_NOR_SKIP_SFDP)) {
+		struct spi_nor_flash_parameter sfdp_params;
+
+		memcpy(&sfdp_params, params, sizeof(sfdp_params));
+		if (spi_nor_parse_sfdp(nor, &sfdp_params)) {
+			nor->addr_width = 0;
+			nor->mtd.erasesize = 0;
+		} else {
+			memcpy(params, &sfdp_params, sizeof(*params));
+		}
+	}
+
 	return 0;
 }
 
@@ -1760,6 +2503,10 @@ static int spi_nor_select_erase(struct spi_nor *nor,
 {
 	struct mtd_info *mtd = &nor->mtd;
 
+	/* Do nothing if already configured from SFDP. */
+	if (mtd->erasesize)
+		return 0;
+
 #ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
 	/* prefer "small sector" erase if possible */
 	if (info->flags & SECT_4K) {
@@ -1992,9 +2739,11 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (ret)
 		return ret;
 
-	if (info->addr_width)
+	if (nor->addr_width) {
+		/* already configured from SFDP */
+	} else if (info->addr_width) {
 		nor->addr_width = info->addr_width;
-	else if (mtd->size > 0x1000000) {
+	} else if (mtd->size > 0x1000000) {
 		/* enable 4-byte addressing if the device exceeds 16MiB */
 		nor->addr_width = 4;
 		if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 55faa2f07cca..0df3638ff0b8 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -41,6 +41,8 @@
 #define SPINOR_OP_WREN		0x06	/* Write enable */
 #define SPINOR_OP_RDSR		0x05	/* Read status register */
 #define SPINOR_OP_WRSR		0x01	/* Write status register 1 byte */
+#define SPINOR_OP_RDSR2		0x3f	/* Read status register 2 */
+#define SPINOR_OP_WRSR2		0x3e	/* Write status register 2 */
 #define SPINOR_OP_READ		0x03	/* Read data bytes (low frequency) */
 #define SPINOR_OP_READ_FAST	0x0b	/* Read data bytes (high frequency) */
 #define SPINOR_OP_READ_1_1_2	0x3b	/* Read data bytes (Dual Output SPI) */
@@ -56,6 +58,7 @@
 #define SPINOR_OP_CHIP_ERASE	0xc7	/* Erase whole flash chip */
 #define SPINOR_OP_SE		0xd8	/* Sector erase (usually 64KiB) */
 #define SPINOR_OP_RDID		0x9f	/* Read JEDEC ID */
+#define SPINOR_OP_RDSFDP	0x5a	/* Read SFDP */
 #define SPINOR_OP_RDCR		0x35	/* Read configuration register */
 #define SPINOR_OP_RDFSR		0x70	/* Read flag status register */
 
@@ -128,6 +131,9 @@
 /* Configuration Register bits. */
 #define CR_QUAD_EN_SPAN		BIT(1)	/* Spansion Quad I/O */
 
+/* Status Register 2 bits. */
+#define SR2_QUAD_EN_BIT7	BIT(7)
+
 /* Supported SPI protocols */
 #define SNOR_PROTO_INST_MASK	GENMASK(23, 16)
 #define SNOR_PROTO_INST_SHIFT	16
-- 
2.7.4

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