[PATCH v5 0/3] mtd: spi-nor: OTP support

[PATCH v5 0/3] mtd: spi-nor: OTP support

[Michael Walle]

This patchset implements the MTD OTP functions to allow access to the SPI
OTP data. Specific support is added for Winbond flash chips.

In the past there was already an attempt by Rahul Bedarkar to add this, but
there was no response. These patches are slightly based on his work.

https://lore.kernel.org/linux-mtd/1489754636-21461-1-git-send-email-rahul.bedarkar@imgtec.com/

Changes since v4:
 - s/u_char/u8/
 - dropped extra whitespace
 - moved nor->params->otp.org assignment
 - moved spi_nor_otp_init() after spi_nor_init()
 - keep fixups as last property in struct spi_nor_flash_parameter
 - dropped spi_nor_otp_ops()
 - use i instead of region
 - move otp.o to the list of core objects

Changes since v3:
 - remapped the OTP regions to a contiguous area starting at 0. The
   chips/cfi_cmdset_000[12].c remap the regions, too.
 - with that in place, read/write/lock/erase spanning multiple OTP
   regions are possible
 - picked up Tudors review remarks
 - added new erase support as RFC because MTD API/ABI is still missing.
   Feel free to review, but don't apply it.

Changes since v2:
 - improved commit messages
 - add buffer size check in spi_nor_mtd_otp_info(). just to be sure, the
   buffer is hardcoded to 4k by the mtd subsys
 - moved all code to otp.c
 - dropped the patches introduced in v2

Changes since v1:
 - added methods for Macronix and similar flashes
 - added patch to cleanup/consolidate code in core.c

Michael Walle (3):
  mtd: spi-nor: add OTP support
  mtd: spi-nor: implement OTP support for Winbond and similar flashes
  mtd: spi-nor: winbond: add OTP support to w25q32fw/jw

 drivers/mtd/spi-nor/Makefile  |   2 +-
 drivers/mtd/spi-nor/core.c    |   7 +-
 drivers/mtd/spi-nor/core.h    |  60 ++++++
 drivers/mtd/spi-nor/otp.c     | 384 ++++++++++++++++++++++++++++++++++
 drivers/mtd/spi-nor/winbond.c |  17 +-
 include/linux/mtd/spi-nor.h   |   8 +
 6 files changed, 474 insertions(+), 4 deletions(-)
 create mode 100644 drivers/mtd/spi-nor/otp.c

-- 
2.20.1

[PATCH v5 1/3] mtd: spi-nor: add OTP support

[Michael Walle]

SPI flashes sometimes have a special OTP area, which can (and is) used to
store immutable properties like board serial number or vendor assigned
network hardware addresses.

The MTD subsystem already supports accessing such areas and some (non
SPI NOR) flashes already implement support for it. It differentiates
between user and factory areas. User areas can be written by the user and
factory ones are pre-programmed and locked down by the vendor, usually
containing an "electrical serial number". This patch will only add support
for the user areas.

Lay the foundation and implement the MTD callbacks for the SPI NOR and add
necessary parameters to the flash_info structure. If a flash supports OTP
it can be added by the convenience macro OTP_INFO(). Sometimes there are
individual regions, which might have individual offsets. Therefore, it is
possible to specify the starting address of the first regions as well as
the distance between two regions (e.g. Winbond devices uses this method).

Additionally, the regions might be locked down. Once locked, no further
write access is possible.

For SPI NOR flashes the OTP area is accessed like the normal memory, e.g.
by offset addressing; except that you either have to use special read/write
commands (Winbond) or you have to enter (and exit) a specific OTP mode
(Macronix, Micron).

Thus we introduce four operations to which the MTD callbacks will be
mapped: .read(), .write(), .lock() and .is_locked(). The read and the write
ops will be given an address offset to operate on while the locking ops use
regions because locking always affects a whole region. It is up to the
flash driver to implement these ops.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/mtd/spi-nor/Makefile |   2 +-
 drivers/mtd/spi-nor/core.c   |   5 +
 drivers/mtd/spi-nor/core.h   |  54 +++++++++
 drivers/mtd/spi-nor/otp.c    | 217 +++++++++++++++++++++++++++++++++++
 4 files changed, 277 insertions(+), 1 deletion(-)
 create mode 100644 drivers/mtd/spi-nor/otp.c

diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
index 653923896205..8a526554f2e2 100644
--- a/drivers/mtd/spi-nor/Makefile
+++ b/drivers/mtd/spi-nor/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-spi-nor-objs			:= core.o sfdp.o
+spi-nor-objs			:= core.o sfdp.o otp.o
 spi-nor-objs			+= atmel.o
 spi-nor-objs			+= catalyst.o
 spi-nor-objs			+= eon.o
diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index fbc34158a883..5e8218e53ec7 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2918,6 +2918,8 @@ static void spi_nor_info_init_params(struct spi_nor *nor)
 	params->quad_enable = spi_nor_sr2_bit1_quad_enable;
 	params->set_4byte_addr_mode = spansion_set_4byte_addr_mode;
 	params->setup = spi_nor_default_setup;
+	nor->params->otp.org = &info->otp_org;
+
 	/* Default to 16-bit Write Status (01h) Command */
 	nor->flags |= SNOR_F_HAS_16BIT_SR;
 
@@ -3556,6 +3558,9 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (ret)
 		return ret;
 
+	/* Configure OTP parameters and ops */
+	spi_nor_otp_init(nor);
+
 	dev_info(dev, "%s (%lld Kbytes)\n", info->name,
 			(long long)mtd->size >> 10);
 
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index db07832ee66c..18521603b012 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -187,6 +187,45 @@ struct spi_nor_locking_ops {
 	int (*is_locked)(struct spi_nor *nor, loff_t ofs, uint64_t len);
 };
 
+/**
+ * struct spi_nor_otp_organization - Structure to describe the SPI NOR OTP regions
+ * @len:	size of one OTP region in bytes.
+ * @base:	start address of the OTP area.
+ * @offset:	offset between consecutive OTP regions if there are more
+ *              than one.
+ * @n_regions:	number of individual OTP regions.
+ */
+struct spi_nor_otp_organization {
+	size_t len;
+	loff_t base;
+	loff_t offset;
+	unsigned int n_regions;
+};
+
+/**
+ * struct spi_nor_otp_ops - SPI NOR OTP methods
+ * @read:	read from the SPI NOR OTP area.
+ * @write:	write to the SPI NOR OTP area.
+ * @lock:	lock an OTP region.
+ * @is_locked:	check if an OTP region of the SPI NOR is locked.
+ */
+struct spi_nor_otp_ops {
+	int (*read)(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf);
+	int (*write)(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf);
+	int (*lock)(struct spi_nor *nor, unsigned int region);
+	int (*is_locked)(struct spi_nor *nor, unsigned int region);
+};
+
+/**
+ * struct spi_nor_otp - SPI NOR OTP grouping structure
+ * @org:	OTP region organization
+ * @ops:	OTP access ops
+ */
+struct spi_nor_otp {
+	const struct spi_nor_otp_organization *org;
+	const struct spi_nor_otp_ops *ops;
+};
+
 /**
  * struct spi_nor_flash_parameter - SPI NOR flash parameters and settings.
  * Includes legacy flash parameters and settings that can be overwritten
@@ -208,6 +247,7 @@ struct spi_nor_locking_ops {
  *                      higher index in the array, the higher priority.
  * @erase_map:		the erase map parsed from the SFDP Sector Map Parameter
  *                      Table.
+ * @otp_info:		describes the OTP regions.
  * @octal_dtr_enable:	enables SPI NOR octal DTR mode.
  * @quad_enable:	enables SPI NOR quad mode.
  * @set_4byte_addr_mode: puts the SPI NOR in 4 byte addressing mode.
@@ -219,6 +259,7 @@ struct spi_nor_locking_ops {
  *                      e.g. different opcodes, specific address calculation,
  *                      page size, etc.
  * @locking_ops:	SPI NOR locking methods.
+ * @otp:		SPI NOR OTP methods.
  */
 struct spi_nor_flash_parameter {
 	u64				size;
@@ -232,6 +273,7 @@ struct spi_nor_flash_parameter {
 	struct spi_nor_pp_command	page_programs[SNOR_CMD_PP_MAX];
 
 	struct spi_nor_erase_map        erase_map;
+	struct spi_nor_otp		otp;
 
 	int (*octal_dtr_enable)(struct spi_nor *nor, bool enable);
 	int (*quad_enable)(struct spi_nor *nor);
@@ -338,6 +380,8 @@ struct flash_info {
 					 * power-up in a write-protected state.
 					 */
 
+	const struct spi_nor_otp_organization otp_org;
+
 	/* Part specific fixup hooks. */
 	const struct spi_nor_fixups *fixups;
 };
@@ -392,6 +436,14 @@ struct flash_info {
 		.addr_width = 3,					\
 		.flags = SPI_NOR_NO_FR | SPI_NOR_XSR_RDY,
 
+#define OTP_INFO(_len, _n_regions, _base, _offset)			\
+		.otp_org = {						\
+			.len = (_len),					\
+			.base = (_base),				\
+			.offset = (_offset),				\
+			.n_regions = (_n_regions),			\
+		},
+
 /**
  * struct spi_nor_manufacturer - SPI NOR manufacturer object
  * @name: manufacturer name
@@ -471,6 +523,8 @@ int spi_nor_post_bfpt_fixups(struct spi_nor *nor,
 			     const struct sfdp_parameter_header *bfpt_header,
 			     const struct sfdp_bfpt *bfpt);
 
+void spi_nor_otp_init(struct spi_nor *nor);
+
 static struct spi_nor __maybe_unused *mtd_to_spi_nor(struct mtd_info *mtd)
 {
 	return mtd->priv;
diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
new file mode 100644
index 000000000000..bc580a386883
--- /dev/null
+++ b/drivers/mtd/spi-nor/otp.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OTP support for SPI NOR flashes
+ *
+ * Copyright (C) 2021 Michael Walle <michael@walle.cc>
+ */
+
+#include <linux/log2.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/spi-nor.h>
+
+#include "core.h"
+
+#define spi_nor_otp_region_len(nor) ((nor)->params->otp.org->len)
+#define spi_nor_otp_n_regions(nor) ((nor)->params->otp.org->n_regions)
+
+static loff_t spi_nor_otp_region_start(const struct spi_nor *nor, int region)
+{
+	const struct spi_nor_otp_organization *org = nor->params->otp.org;
+
+	return org->base + region * org->offset;
+}
+
+static size_t spi_nor_otp_size(struct spi_nor *nor)
+{
+	return spi_nor_otp_n_regions(nor) * spi_nor_otp_region_len(nor);
+}
+
+/*
+ * Translate the file offsets from and to OTP regions. See also
+ * spi_nor_mtd_otp_do_op().
+ */
+static loff_t spi_nor_otp_region_to_offset(struct spi_nor *nor, unsigned int region)
+{
+	return region * spi_nor_otp_region_len(nor);
+}
+
+static unsigned int spi_nor_otp_offset_to_region(struct spi_nor *nor, loff_t ofs)
+{
+	return ofs / spi_nor_otp_region_len(nor);
+}
+
+static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len,
+				size_t *retlen, struct otp_info *buf)
+{
+	struct spi_nor *nor = mtd_to_spi_nor(mtd);
+	const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+	unsigned int n_regions = spi_nor_otp_n_regions(nor);
+	unsigned int i;
+	int ret, locked;
+
+	if (len < n_regions * sizeof(*buf))
+		return -ENOSPC;
+
+	ret = spi_nor_lock_and_prep(nor);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < n_regions; i++) {
+		buf->start = spi_nor_otp_region_to_offset(nor, i);
+		buf->length = spi_nor_otp_region_len(nor);
+
+		locked = ops->is_locked(nor, i);
+		if (locked < 0) {
+			ret = locked;
+			goto out;
+		}
+
+		buf->locked = !!locked;
+		buf++;
+	}
+
+	*retlen = n_regions * sizeof(*buf);
+
+out:
+	spi_nor_unlock_and_unprep(nor);
+
+	return ret;
+}
+
+static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
+				      size_t total_len, size_t *retlen,
+				      u8 *buf, bool is_write)
+{
+	struct spi_nor *nor = mtd_to_spi_nor(mtd);
+	const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+	const size_t rlen = spi_nor_otp_region_len(nor);
+	loff_t rstart, rofs;
+	unsigned int region;
+	size_t len;
+	int ret;
+
+	if (ofs < 0 || ofs >= spi_nor_otp_size(nor))
+		return 0;
+
+	ret = spi_nor_lock_and_prep(nor);
+	if (ret)
+		return ret;
+
+	/* don't access beyond the end */
+	total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
+
+	*retlen = 0;
+	while (total_len) {
+		/*
+		 * The OTP regions are mapped into a contiguous area starting
+		 * at 0 as expected by the MTD layer. This will map the MTD
+		 * file offsets to the address of an OTP region as used in the
+		 * actual SPI commands.
+		 */
+		region = spi_nor_otp_offset_to_region(nor, ofs);
+		rstart = spi_nor_otp_region_start(nor, region);
+
+		/*
+		 * The size of a OTP region is expected to be a power of two,
+		 * thus we can just mask the lower bits and get the offset into
+		 * a region.
+		 */
+		rofs = ofs & (rlen - 1);
+
+		/* don't access beyond one OTP region */
+		len = min_t(size_t, total_len, rlen - rofs);
+
+		if (is_write)
+			ret = ops->write(nor, rstart + rofs, len, buf);
+		else
+			ret = ops->read(nor, rstart + rofs, len, buf);
+		if (ret == 0)
+			ret = -EIO;
+		if (ret < 0)
+			goto out;
+
+		*retlen += ret;
+		ofs += ret;
+		buf += ret;
+		total_len -= ret;
+	}
+	ret = 0;
+
+out:
+	spi_nor_unlock_and_unprep(nor);
+	return ret;
+}
+
+static int spi_nor_mtd_otp_read(struct mtd_info *mtd, loff_t from, size_t len,
+				size_t *retlen, u8 *buf)
+{
+	return spi_nor_mtd_otp_read_write(mtd, from, len, retlen, buf, false);
+}
+
+static int spi_nor_mtd_otp_write(struct mtd_info *mtd, loff_t to, size_t len,
+				 size_t *retlen, u8 *buf)
+{
+	return spi_nor_mtd_otp_read_write(mtd, to, len, retlen, buf, true);
+}
+
+static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)
+{
+	struct spi_nor *nor = mtd_to_spi_nor(mtd);
+	const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+	unsigned int region;
+	int ret;
+
+	if (from < 0 || (from + len) > spi_nor_otp_size(nor))
+		return -EINVAL;
+
+	/* the user has to explicitly ask for whole regions */
+	if (len % spi_nor_otp_region_len(nor))
+		return -EINVAL;
+
+	if (from % spi_nor_otp_region_len(nor))
+		return -EINVAL;
+
+	ret = spi_nor_lock_and_prep(nor);
+	if (ret)
+		return ret;
+
+	while (len) {
+		region = spi_nor_otp_offset_to_region(nor, from);
+		ret = ops->lock(nor, region);
+		if (ret)
+			goto out;
+
+		len -= spi_nor_otp_region_len(nor);
+		from += spi_nor_otp_region_len(nor);
+	}
+
+out:
+	spi_nor_unlock_and_unprep(nor);
+
+	return ret;
+}
+
+void spi_nor_otp_init(struct spi_nor *nor)
+{
+	struct mtd_info *mtd = &nor->mtd;
+
+	if (!nor->params->otp.ops)
+		return;
+
+	if (WARN_ON(!is_power_of_2(spi_nor_otp_region_len(nor))))
+		return;
+
+	/*
+	 * We only support user_prot callbacks (yet).
+	 *
+	 * Some SPI NOR flashes like Macronix ones can be ordered in two
+	 * different variants. One with a factory locked OTP area and one where
+	 * it is left to the user to write to it. The factory locked OTP is
+	 * usually preprogrammed with an "electrical serial number". We don't
+	 * support these for now.
+	 */
+	mtd->_get_user_prot_info = spi_nor_mtd_otp_info;
+	mtd->_read_user_prot_reg = spi_nor_mtd_otp_read;
+	mtd->_write_user_prot_reg = spi_nor_mtd_otp_write;
+	mtd->_lock_user_prot_reg = spi_nor_mtd_otp_lock;
+}
-- 
2.20.1

[PATCH v5 2/3] mtd: spi-nor: implement OTP support for Winbond and similar flashes

[Michael Walle]

Use the new OTP ops to implement OTP access on Winbond flashes. Most
Winbond flashes provides up to four different OTP regions ("Security
Registers").

Winbond devices use a special opcode to read and write to the OTP
regions, just like the RDSFDP opcode. In fact, it seems that the
(undocumented) first OTP area of the newer flashes is the actual SFDP
table.

On a side note, Winbond devices also allow erasing the OTP regions as
long as the area isn't locked down.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/mtd/spi-nor/core.c  |   2 +-
 drivers/mtd/spi-nor/core.h  |   6 ++
 drivers/mtd/spi-nor/otp.c   | 164 ++++++++++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h |   8 ++
 4 files changed, 179 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 5e8218e53ec7..3e6fbc9d53ef 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1034,7 +1034,7 @@ static int spi_nor_write_16bit_sr_and_check(struct spi_nor *nor, u8 sr1)
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
+int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
 {
 	int ret;
 	u8 *sr_cr = nor->bouncebuf;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 18521603b012..8b1f900e0e0a 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -495,6 +495,7 @@ int spi_nor_read_sr(struct spi_nor *nor, u8 *sr);
 int spi_nor_read_cr(struct spi_nor *nor, u8 *cr);
 int spi_nor_write_sr(struct spi_nor *nor, const u8 *sr, size_t len);
 int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1);
+int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr);
 
 int spi_nor_xread_sr(struct spi_nor *nor, u8 *sr);
 ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
@@ -502,6 +503,11 @@ ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
 ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
 			   const u8 *buf);
 
+int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf);
+int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf);
+int spi_nor_otp_lock_sr2(struct spi_nor *nor, unsigned int region);
+int spi_nor_otp_is_locked_sr2(struct spi_nor *nor, unsigned int region);
+
 int spi_nor_hwcaps_read2cmd(u32 hwcaps);
 u8 spi_nor_convert_3to4_read(u8 opcode);
 void spi_nor_set_read_settings(struct spi_nor_read_command *read,
diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
index bc580a386883..40fa31d8fe38 100644
--- a/drivers/mtd/spi-nor/otp.c
+++ b/drivers/mtd/spi-nor/otp.c
@@ -14,6 +14,170 @@
 #define spi_nor_otp_region_len(nor) ((nor)->params->otp.org->len)
 #define spi_nor_otp_n_regions(nor) ((nor)->params->otp.org->n_regions)
 
+/**
+ * spi_nor_otp_read_secr() - read OTP data
+ * @nor:	pointer to 'struct spi_nor'
+ * @from:       offset to read from
+ * @len:        number of bytes to read
+ * @buf:        pointer to dst buffer
+ *
+ * Read OTP data from one region by using the SPINOR_OP_RSECR commands. This
+ * method is used on GigaDevice and Winbond flashes.
+ *
+ * Return: number of bytes read successfully, -errno otherwise
+ */
+int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
+{
+	u8 addr_width, read_opcode, read_dummy;
+	struct spi_mem_dirmap_desc *rdesc;
+	enum spi_nor_protocol read_proto;
+	int ret;
+
+	read_opcode = nor->read_opcode;
+	addr_width = nor->addr_width;
+	read_dummy = nor->read_dummy;
+	read_proto = nor->read_proto;
+	rdesc = nor->dirmap.rdesc;
+
+	nor->read_opcode = SPINOR_OP_RSECR;
+	nor->addr_width = 3;
+	nor->read_dummy = 8;
+	nor->read_proto = SNOR_PROTO_1_1_1;
+	nor->dirmap.rdesc = NULL;
+
+	ret = spi_nor_read_data(nor, addr, len, buf);
+
+	nor->read_opcode = read_opcode;
+	nor->addr_width = addr_width;
+	nor->read_dummy = read_dummy;
+	nor->read_proto = read_proto;
+	nor->dirmap.rdesc = rdesc;
+
+	return ret;
+}
+
+/**
+ * spi_nor_otp_write_secr() - write OTP data
+ * @nor:        pointer to 'struct spi_nor'
+ * @to:         offset to write to
+ * @len:        number of bytes to write
+ * @buf:        pointer to src buffer
+ *
+ * Write OTP data to one region by using the SPINOR_OP_PSECR commands. This
+ * method is used on GigaDevice and Winbond flashes.
+ *
+ * Please note, the write must not span multiple OTP regions.
+ *
+ * Return: number of bytes written successfully, -errno otherwise
+ */
+int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
+{
+	enum spi_nor_protocol write_proto;
+	struct spi_mem_dirmap_desc *wdesc;
+	u8 addr_width, program_opcode;
+	int ret, written;
+
+	program_opcode = nor->program_opcode;
+	addr_width = nor->addr_width;
+	write_proto = nor->write_proto;
+	wdesc = nor->dirmap.wdesc;
+
+	nor->program_opcode = SPINOR_OP_PSECR;
+	nor->addr_width = 3;
+	nor->write_proto = SNOR_PROTO_1_1_1;
+	nor->dirmap.wdesc = NULL;
+
+	/*
+	 * We only support a write to one single page. For now all winbond
+	 * flashes only have one page per OTP region.
+	 */
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		goto out;
+
+	written = spi_nor_write_data(nor, addr, len, buf);
+	if (written < 0)
+		goto out;
+
+	ret = spi_nor_wait_till_ready(nor);
+
+out:
+	nor->program_opcode = program_opcode;
+	nor->addr_width = addr_width;
+	nor->write_proto = write_proto;
+	nor->dirmap.wdesc = wdesc;
+
+	return ret ?: written;
+}
+
+static int spi_nor_otp_lock_bit_cr(unsigned int region)
+{
+	static const int lock_bits[] = { SR2_LB1, SR2_LB2, SR2_LB3 };
+
+	if (region >= ARRAY_SIZE(lock_bits))
+		return -EINVAL;
+
+	return lock_bits[region];
+}
+
+/**
+ * spi_nor_otp_lock_sr2() - lock the OTP region
+ * @nor:        pointer to 'struct spi_nor'
+ * @region:     OTP region
+ *
+ * Lock the OTP region by writing the status register-2. This method is used on
+ * GigaDevice and Winbond flashes.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_otp_lock_sr2(struct spi_nor *nor, unsigned int region)
+{
+	u8 *cr = nor->bouncebuf;
+	int ret, lock_bit;
+
+	lock_bit = spi_nor_otp_lock_bit_cr(region);
+	if (lock_bit < 0)
+		return lock_bit;
+
+	ret = spi_nor_read_cr(nor, cr);
+	if (ret)
+		return ret;
+
+	/* no need to write the register if region is already locked */
+	if (cr[0] & lock_bit)
+		return 0;
+
+	cr[0] |= lock_bit;
+
+	return spi_nor_write_16bit_cr_and_check(nor, cr[0]);
+}
+
+/**
+ * spi_nor_otp_is_locked_sr2() - get the OTP region lock status
+ * @nor:        pointer to 'struct spi_nor'
+ * @region:     OTP region
+ *
+ * Retrieve the OTP region lock bit by reading the status register-2. This
+ * method is used on GigaDevice and Winbond flashes.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_otp_is_locked_sr2(struct spi_nor *nor, unsigned int region)
+{
+	u8 *cr = nor->bouncebuf;
+	int ret, lock_bit;
+
+	lock_bit = spi_nor_otp_lock_bit_cr(region);
+	if (lock_bit < 0)
+		return lock_bit;
+
+	ret = spi_nor_read_cr(nor, cr);
+	if (ret)
+		return ret;
+
+	return cr[0] & lock_bit;
+}
+
 static loff_t spi_nor_otp_region_start(const struct spi_nor *nor, int region)
 {
 	const struct spi_nor_otp_organization *org = nor->params->otp.org;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index a0d572855444..98ed91b529ea 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -107,6 +107,11 @@
 #define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */
 #define SPINOR_OP_WD_EVCR      0x61    /* Write EVCR register */
 
+/* Used for GigaDevices and Winbond flashes. */
+#define SPINOR_OP_ESECR		0x44	/* Erase Security registers */
+#define SPINOR_OP_PSECR		0x42	/* Program Security registers */
+#define SPINOR_OP_RSECR		0x48	/* Read Security registers */
+
 /* Status Register bits. */
 #define SR_WIP			BIT(0)	/* Write in progress */
 #define SR_WEL			BIT(1)	/* Write enable latch */
@@ -138,6 +143,9 @@
 
 /* Status Register 2 bits. */
 #define SR2_QUAD_EN_BIT1	BIT(1)
+#define SR2_LB1			BIT(3)	/* Security Register Lock Bit 1 */
+#define SR2_LB2			BIT(4)	/* Security Register Lock Bit 2 */
+#define SR2_LB3			BIT(5)	/* Security Register Lock Bit 3 */
 #define SR2_QUAD_EN_BIT7	BIT(7)
 
 /* Supported SPI protocols */
-- 
2.20.1

[PATCH v5 3/3] mtd: spi-nor: winbond: add OTP support to w25q32fw/jw

[Michael Walle]

With all the helper functions in place, add OTP support for the Winbond
W25Q32JW and W25Q32FW.

Both were tested on a LS1028A SoC with a NXP FSPI controller.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/mtd/spi-nor/winbond.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 20b2c6f19d6f..9a81c67a60c6 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -54,14 +54,18 @@ static const struct flash_info winbond_parts[] = {
 	{ "w25q32", INFO(0xef4016, 0, 64 * 1024,  64, SECT_4K) },
 	{ "w25q32dw", INFO(0xef6016, 0, 64 * 1024,  64,
 			   SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
-			   SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB) },
+			   SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB)
+			   OTP_INFO(256, 3, 0x1000, 0x1000)
+	},
+
 	{ "w25q32jv", INFO(0xef7016, 0, 64 * 1024,  64,
 			   SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
 			   SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB)
 	},
 	{ "w25q32jwm", INFO(0xef8016, 0, 64 * 1024,  64,
 			    SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
-			    SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB) },
+			    SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB)
+			    OTP_INFO(256, 3, 0x1000, 0x1000) },
 	{ "w25q64jwm", INFO(0xef8017, 0, 64 * 1024, 128,
 			    SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
 			    SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB) },
@@ -132,9 +136,18 @@ static int winbond_set_4byte_addr_mode(struct spi_nor *nor, bool enable)
 	return spi_nor_write_disable(nor);
 }
 
+static const struct spi_nor_otp_ops winbond_otp_ops = {
+	.read = spi_nor_otp_read_secr,
+	.write = spi_nor_otp_write_secr,
+	.lock = spi_nor_otp_lock_sr2,
+	.is_locked = spi_nor_otp_is_locked_sr2,
+};
+
 static void winbond_default_init(struct spi_nor *nor)
 {
 	nor->params->set_4byte_addr_mode = winbond_set_4byte_addr_mode;
+	if (nor->params->otp.org->n_regions)
+		nor->params->otp.ops = &winbond_otp_ops;
 }
 
 static const struct spi_nor_fixups winbond_fixups = {
-- 
2.20.1

Re: [PATCH v5 0/3] mtd: spi-nor: OTP support

[Tudor Ambarus]

On Mon, 22 Mar 2021 00:51:37 +0100, Michael Walle wrote:
> This patchset implements the MTD OTP functions to allow access to the SPI
> OTP data. Specific support is added for Winbond flash chips.
> 
> In the past there was already an attempt by Rahul Bedarkar to add this, but
> there was no response. These patches are slightly based on his work.
> 
> https://lore.kernel.org/linux-mtd/1489754636-21461-1-git-send-email-rahul.bedarkar@imgtec.com/
> 
> [...]

Update 1/3: use div64_u64(), IS_ALIGNED, params->otp.org.
unsigned int region, drop comment, add rlen local variable in spi_nor_mtd_otp_lock()

Applied to spi-nor/next, thanks!

[1/3] mtd: spi-nor: add OTP support
      https://git.kernel.org/mtd/c/06d4bdf0a329
[2/3] mtd: spi-nor: implement OTP support for Winbond and similar flashes
      https://git.kernel.org/mtd/c/10488a53bdc4
[3/3] mtd: spi-nor: winbond: add OTP support to w25q32fw/jw
      https://git.kernel.org/mtd/c/5909dde2bc53

Best regards,
-- 
Tudor Ambarus <tudor.ambarus@microchip.com>