linux-kernel - [PATCH 2/2] mtd: spi-nor: Avoid setting SRWD bit in SR if WP signal not connected

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Date:   Thu, 15 Jun 2023 16:46:49 +0530
From:   Amit Kumar Mahapatra <amit.kumar-mahapatra@....com>
To:     <tudor.ambarus@...aro.org>, <pratyush@...nel.org>,
        <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <conor+dt@...nel.org>
CC:     <git@....com>, <michael@...le.cc>, <linux-mtd@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <amitrkcian2002@...il.com>,
        Amit Kumar Mahapatra <amit.kumar-mahapatra@....com>
Subject: [PATCH 2/2] mtd: spi-nor: Avoid setting SRWD bit in SR if WP signal not connected

Setting the status register write disable (SRWD) bit in the status
register (SR) with WP signal of the flash not connected will configure the
SR permanently as read-only. If WP signal is not connected, avoid setting
SRWD bit while writing the SR during flash protection.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@....com>
---
 drivers/mtd/spi-nor/core.c | 3 +++
 drivers/mtd/spi-nor/core.h | 1 +
 drivers/mtd/spi-nor/swp.c  | 5 +++--
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 0bb0ad14a2fc..81b57c51f41c 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2864,6 +2864,9 @@ static void spi_nor_init_flags(struct spi_nor *nor)
 	if (flags & NO_CHIP_ERASE)
 		nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
 
+	if (of_property_read_bool(np, "broken-wp"))
+		nor->flags |= SNOR_F_BROKEN_WP;
+
 	if (flags & SPI_NOR_RWW && nor->info->n_banks > 1 &&
 	    !nor->controller_ops)
 		nor->flags |= SNOR_F_RWW;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 4fb5ff09c63a..6ac932eba913 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -132,6 +132,7 @@ enum spi_nor_option_flags {
 	SNOR_F_SWP_IS_VOLATILE	= BIT(13),
 	SNOR_F_RWW		= BIT(14),
 	SNOR_F_ECC		= BIT(15),
+	SNOR_F_BROKEN_WP	= BIT(16),
 };
 
 struct spi_nor_read_command {
diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 0ba716e84377..074f3bce2034 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -214,8 +214,9 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 
 	status_new = (status_old & ~mask & ~tb_mask) | val;
 
-	/* Disallow further writes if WP pin is asserted */
-	status_new |= SR_SRWD;
+	/* Disallow further writes if WP pin is connected */
+	if (!(nor->flags & SNOR_F_BROKEN_WP))
+		status_new |= SR_SRWD;
 
 	if (!use_top)
 		status_new |= tb_mask;
-- 
2.17.1