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From:   Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
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        Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Subject: [PATCH v2 2/2] mtd: spi-nor: Avoid setting SRWD bit in SR if WP signal not connected
Date:   Fri, 16 Jun 2023 14:25:13 +0530
Message-ID: <20230616085513.17632-3-amit.kumar-mahapatra@amd.com>
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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@amd.com>
---
 drivers/mtd/spi-nor/core.c | 3 +++
 drivers/mtd/spi-nor/core.h | 1 +
 drivers/mtd/spi-nor/swp.c  | 9 +++++++--
 3 files changed, 11 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..5d91f152c2cc 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -214,8 +214,13 @@ 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 not broken. WP pin is
+	 * considered broken only if the WP signal of the flash device
+	 * is not connected.
+	 */
+	if (!(nor->flags & SNOR_F_BROKEN_WP))
+		status_new |= SR_SRWD;
 
 	if (!use_top)
 		status_new |= tb_mask;
-- 
2.17.1