[PATCH v2] mtd: spi-nor: implement OTP erase for Winbond and similar flashes

Michael Walle
2021-05-10T20:22:08Z

Winbond flashes with OTP support provide a command to erase the OTP
data. This might come in handy during development.

This was tested with a Winbond W25Q32JW on a LS1028A SoC with the
NXP FSPI controller.

Signed-off-by: Michael Walle <michael@walle.cc>
---
Changes since v1:
- fixed kernel doc

There is also a patch for mtd-utils to add a small tool to issue
the erase:
https://lore.kernel.org/linux-mtd/20210510201319.25975-1-michael@walle.cc/

drivers/mtd/spi-nor/core.c | 4 +-
drivers/mtd/spi-nor/core.h | 4 ++
drivers/mtd/spi-nor/otp.c | 73 ++++++++++++++++++++++++++++++++++-
drivers/mtd/spi-nor/winbond.c | 1 +
4 files changed, 78 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index bd2c7717eb10..fac8717f651f 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -166,8 +166,8 @@ static int spi_nor_controller_ops_read_reg(struct spi_nor *nor, u8 opcode,
return nor->controller_ops->read_reg(nor, opcode, buf, len);
}

-static int spi_nor_controller_ops_write_reg(struct spi_nor *nor, u8 opcode,
- const u8 *buf, size_t len)
+int spi_nor_controller_ops_write_reg(struct spi_nor *nor, u8 opcode,
+ const u8 *buf, size_t len)
{
if (spi_nor_protocol_is_dtr(nor->reg_proto))
return -EOPNOTSUPP;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 28a2e0be97a3..b410e4eec2fb 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -214,6 +214,7 @@ struct spi_nor_otp_ops {
int (*write)(struct spi_nor *nor, loff_t addr, size_t len,
const u8 *buf);
int (*lock)(struct spi_nor *nor, unsigned int region);
+ int (*erase)(struct spi_nor *nor, loff_t addr);
int (*is_locked)(struct spi_nor *nor, unsigned int region);
};

@@ -481,6 +482,8 @@ extern const struct spi_nor_manufacturer spi_nor_xmc;
void spi_nor_spimem_setup_op(const struct spi_nor *nor,
struct spi_mem_op *op,
const enum spi_nor_protocol proto);
+int spi_nor_controller_ops_write_reg(struct spi_nor *nor, u8 opcode,
+ const u8 *buf, size_t len);
int spi_nor_write_enable(struct spi_nor *nor);
int spi_nor_write_disable(struct spi_nor *nor);
int spi_nor_set_4byte_addr_mode(struct spi_nor *nor, bool enable);
@@ -507,6 +510,7 @@ ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
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,
const u8 *buf);
+int spi_nor_otp_erase_secr(struct spi_nor *nor, loff_t addr);
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);

diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
index 61036c716abb..d3ca73c8cc53 100644
--- a/drivers/mtd/spi-nor/otp.c
+++ b/drivers/mtd/spi-nor/otp.c
@@ -8,6 +8,7 @@
#include <linux/log2.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/spi-nor.h>
+#include <linux/spi/spi-mem.h>

#include "core.h"

@@ -111,6 +112,48 @@ int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len,
return ret ?: written;
}

+/**
+ * spi_nor_otp_erase_secr() - erase one OTP region
+ * @nor: pointer to 'struct spi_nor'
+ * @addr: offset of the OTP region to be erased
+ *
+ * Erase one OTP region by using the SPINOR_OP_ESECR commands. This method is
+ * used on GigaDevice and Winbond flashes.
+ *
+ * Return: 0 on success, -errno otherwise
+ */
+int spi_nor_otp_erase_secr(struct spi_nor *nor, loff_t addr)
+{
+ int ret;
+
+ ret = spi_nor_write_enable(nor);
+ if (ret)
+ return ret;
+
+ if (nor->spimem) {
+ struct spi_mem_op op =
+ SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_ESECR, 0),
+ SPI_MEM_OP_ADDR(3, addr, 0),
+ SPI_MEM_OP_NO_DUMMY,
+ SPI_MEM_OP_NO_DATA);
+
+ spi_nor_spimem_setup_op(nor, &op, nor->write_proto);
+
+ ret = spi_mem_exec_op(nor->spimem, &op);
+ } else {
+ nor->bouncebuf[2] = addr & 0xff;
+ nor->bouncebuf[1] = (addr >> 8) & 0xff;
+ nor->bouncebuf[0] = (addr >> 16) & 0xff;
+
+ ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_ESECR,
+ nor->bouncebuf, 3);
+ }
+ if (ret)
+ return ret;
+
+ return spi_nor_wait_till_ready(nor);
+}
+
static int spi_nor_otp_lock_bit_cr(unsigned int region)
{
static const int lock_bits[] = { SR2_LB1, SR2_LB2, SR2_LB3 };
@@ -316,12 +359,14 @@ static int spi_nor_mtd_otp_write(struct mtd_info *mtd, loff_t to, size_t len,
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)
+static int spi_nor_mtd_otp_lock_erase(struct mtd_info *mtd, loff_t from,
+ size_t len, bool is_erase)
{
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);
unsigned int region;
+ loff_t rstart;
int ret;

if (from < 0 || (from + len) > spi_nor_otp_size(nor))
@@ -337,7 +382,13 @@ static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)

while (len) {
region = spi_nor_otp_offset_to_region(nor, from);
- ret = ops->lock(nor, region);
+
+ if (is_erase) {
+ rstart = spi_nor_otp_region_start(nor, region);
+ ret = ops->erase(nor, rstart);
+ } else {
+ ret = ops->lock(nor, region);
+ }
if (ret)
goto out;

@@ -351,6 +402,23 @@ static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)
return ret;
}

+static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)
+{
+ return spi_nor_mtd_otp_lock_erase(mtd, from, len, false);
+}
+
+static int spi_nor_mtd_otp_erase(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;
+
+ /* OTP erase is optional */
+ if (!ops->erase)
+ return -EOPNOTSUPP;
+
+ return spi_nor_mtd_otp_lock_erase(mtd, from, len, true);
+}
+
void spi_nor_otp_init(struct spi_nor *nor)
{
struct mtd_info *mtd = &nor->mtd;
@@ -374,4 +442,5 @@ void spi_nor_otp_init(struct spi_nor *nor)
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;
+ mtd->_erase_user_prot_reg = spi_nor_mtd_otp_erase;
}
diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 9a81c67a60c6..96573f61caf5 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -139,6 +139,7 @@ static int winbond_set_4byte_addr_mode(struct spi_nor *nor, bool enable)
static const struct spi_nor_otp_ops winbond_otp_ops = {
.read = spi_nor_otp_read_secr,
.write = spi_nor_otp_write_secr,
+ .erase = spi_nor_otp_erase_secr,
.lock = spi_nor_otp_lock_sr2,
.is_locked = spi_nor_otp_is_locked_sr2,
};
--
2.20.1