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 <mich...@walle.cc>
---
 drivers/mtd/spi-nor/core.c    |  4 +-
 drivers/mtd/spi-nor/core.h    |  4 ++
 drivers/mtd/spi-nor/otp.c     | 74 ++++++++++++++++++++++++++++++++++-
 drivers/mtd/spi-nor/winbond.c |  1 +
 4 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index ef7df26896f1..21a737804576 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 dfbf6ba42b57..ef62ec4625a1 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -213,6 +213,7 @@ 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 (*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);
@@ -506,6 +509,7 @@ 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, 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 4e8da9108c77..78ec79368c29 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 +112,50 @@ int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t 
addr, size_t len, u8 *buf
        return ret ?: written;
 }
 
+/**
+ * spi_nor_otp_erase_secr() - erase one OTP region
+ * @nor:        pointer to 'struct spi_nor'
+ * @to:         offset to write to
+ * @len:        number of bytes to write
+ * @buf:        pointer to src buffer
+ *
+ * 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 };
@@ -319,11 +364,13 @@ 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 = spi_nor_otp_ops(nor);
        unsigned int region;
+       loff_t start;
        int ret;
 
        if (from < 0 || (from + len) > spi_nor_otp_size(nor))
@@ -342,7 +389,12 @@ 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);
+               start = spi_nor_otp_region_start(nor, region);
+
+               if (is_erase)
+                       ret = ops->erase(nor, start);
+               else
+                       ret = ops->lock(nor, region);
                if (ret)
                        goto out;
 
@@ -356,6 +408,23 @@ 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 = spi_nor_otp_ops(nor);
+
+       /* 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;
@@ -379,4 +448,5 @@ 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 9a3f8ff007fd..e04219ac11fd 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -138,6 +138,7 @@ 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

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