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From:   Michael Walle <michael@walle.cc>
To:     linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     Tudor Ambarus <tudor.ambarus@microchip.com>,
        Michael Walle <michael@walle.cc>,
        Pratyush Yadav <p.yadav@ti.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>
Subject: [PATCH] mtd: spi-nor: implement OTP erase for Winbond and similar flashes
Date:   Wed,  7 Apr 2021 19:18:58 +0200
Message-Id: <20210407171858.8132-1-michael@walle.cc>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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>
---
 drivers/mtd/spi-nor/core.c    |  4 +-
 drivers/mtd/spi-nor/core.h    |  4 ++
 drivers/mtd/spi-nor/otp.c     | 75 ++++++++++++++++++++++++++++++++++-
 drivers/mtd/spi-nor/winbond.c |  1 +
 4 files changed, 80 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 8cf3cf92129e..3f726a87e5a9 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 e9b6b2e76cdb..648e67bea0b2 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);
 };
 
@@ -480,6 +481,8 @@ 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);
@@ -505,6 +508,7 @@ 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 5021d40dffbf..ea7db4b354f7 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"
 
@@ -110,6 +111,50 @@ 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 };
@@ -315,12 +360,14 @@ 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))
@@ -336,7 +383,13 @@ 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;
 
@@ -350,6 +403,23 @@ 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;
@@ -373,4 +443,5 @@ 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