[PATCH v2 1/3] mtd: spi-nor: reimplement block protection handling

[PATCH v2 1/3] mtd: spi-nor: reimplement block protection handling

[Jungseung Lee]

The current mainline locking was restricted and could only be applied
to flashes that has 3 block protection bit and fixed locking ratio.

A new method of normalization was reached at the end of the discussion [1].

    (1) - if bp slot is insufficient.
    (2) - if bp slot is sufficient.

    if (bp_slots_needed > bp_slots)    // (1)
        min_prot_length = sector_size << (bp_slots_needed - bp_slots);
    else                               // (2)
        min_prot_length = sector_size;

This patch changes logic to handle block protection based on min_prot_length.
It is suitable for the overall flashes with exception of some corner case
and easy to extend and apply for the case of 2bit or 4bit block protection.

[1] http://lists.infradead.org/pipermail/linux-mtd/2020-February/093934.html

Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
---
 drivers/mtd/spi-nor/core.c | 110 ++++++++++++++++++++++---------------
 1 file changed, 66 insertions(+), 44 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 877557dbda7f..e4ed8553aae8 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1514,29 +1514,64 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 	return ret;
 }
 
+static u8 spi_nor_get_bp_mask(struct spi_nor *nor)
+{
+	return SR_BP2 | SR_BP1 | SR_BP0;
+}
+
+static u8 spi_nor_get_tb_mask(struct spi_nor *nor)
+{
+	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
+		return SR_TB_BIT6;
+	else
+		return SR_TB_BIT5;
+}
+
+static int spi_nor_get_min_prot_length(struct spi_nor *nor)
+{
+	int bp_slots, bp_slots_needed;
+	u8 mask = spi_nor_get_bp_mask(nor);
+
+	bp_slots = (mask >> SR_BP_SHIFT) + 1;
+
+	/* Reserved one for "protect none" and one for "protect all". */
+	bp_slots = bp_slots - 2;
+
+	bp_slots_needed = ilog2(nor->info->n_sectors);
+
+	if (bp_slots_needed > bp_slots)
+		return nor->info->sector_size <<
+			(bp_slots_needed - bp_slots);
+	else
+		return nor->info->sector_size;
+}
+
 static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
 					uint64_t *len)
 {
 	struct mtd_info *mtd = &nor->mtd;
-	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
-	u8 tb_mask = SR_TB_BIT5;
-	int pow;
-
-	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
-		tb_mask = SR_TB_BIT6;
+	int min_prot_len;
+	u8 mask = spi_nor_get_bp_mask(nor);
+	u8 tb_mask = spi_nor_get_tb_mask(nor);
+	u8 bp = (sr & mask) >> SR_BP_SHIFT;
 
-	if (!(sr & mask)) {
+	if (!bp) {
 		/* No protection */
 		*ofs = 0;
 		*len = 0;
-	} else {
-		pow = ((sr & mask) ^ mask) >> SR_BP_SHIFT;
-		*len = mtd->size >> pow;
-		if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
-			*ofs = 0;
-		else
-			*ofs = mtd->size - *len;
+		return;
 	}
+
+	min_prot_len = spi_nor_get_min_prot_length(nor);
+	*len = min_prot_len << (bp - 1);
+
+	if (*len > mtd->size)
+		*len = mtd->size;
+
+	if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
+		*ofs = 0;
+	else
+		*ofs = mtd->size - *len;
 }
 
 /*
@@ -1610,8 +1645,9 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
 	struct mtd_info *mtd = &nor->mtd;
 	int ret, status_old, status_new;
-	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
-	u8 tb_mask = SR_TB_BIT5;
+	int min_prot_len;
+	u8 mask = spi_nor_get_bp_mask(nor);
+	u8 tb_mask = spi_nor_get_tb_mask(nor);
 	u8 pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
@@ -1648,20 +1684,14 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	else
 		lock_len = ofs + len;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
-		tb_mask = SR_TB_BIT6;
+	if (lock_len == mtd->size) {
+		val = mask; /* fully locked */
+	} else {
+		min_prot_len = spi_nor_get_min_prot_length(nor);
+		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
+		val = pow << SR_BP_SHIFT;
+	}
 
-	/*
-	 * Need smallest pow such that:
-	 *
-	 *   1 / (2^pow) <= (len / size)
-	 *
-	 * so (assuming power-of-2 size) we do:
-	 *
-	 *   pow = ceil(log2(size / len)) = log2(size) - floor(log2(len))
-	 */
-	pow = ilog2(mtd->size) - ilog2(lock_len);
-	val = mask - (pow << SR_BP_SHIFT);
 	if (val & ~mask)
 		return -EINVAL;
 	/* Don't "lock" with no region! */
@@ -1696,8 +1726,9 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
 	struct mtd_info *mtd = &nor->mtd;
 	int ret, status_old, status_new;
-	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
-	u8 tb_mask = SR_TB_BIT5;
+	int min_prot_len;
+	u8 mask = spi_nor_get_bp_mask(nor);
+	u8 tb_mask = spi_nor_get_tb_mask(nor);
 	u8 pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
@@ -1734,22 +1765,13 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	else
 		lock_len = ofs;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
-		tb_mask = SR_TB_BIT6;
-	/*
-	 * Need largest pow such that:
-	 *
-	 *   1 / (2^pow) >= (len / size)
-	 *
-	 * so (assuming power-of-2 size) we do:
-	 *
-	 *   pow = floor(log2(size / len)) = log2(size) - ceil(log2(len))
-	 */
-	pow = ilog2(mtd->size) - order_base_2(lock_len);
 	if (lock_len == 0) {
 		val = 0; /* fully unlocked */
 	} else {
-		val = mask - (pow << SR_BP_SHIFT);
+		min_prot_len = spi_nor_get_min_prot_length(nor);
+		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
+		val = pow << SR_BP_SHIFT;
+
 		/* Some power-of-two sizes are not supported */
 		if (val & ~mask)
 			return -EINVAL;
-- 
2.17.1


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[PATCH v2 2/3] mtd: spi-nor: add 4bit block protection support

[Jungseung Lee]

Currently, we are supporting block protection only for flash chips with
3 block protection bits in the SR register.

This patch enables block protection support for flashes with 4 block
protection bits(bp0-3).

Added a flag to inform that this flash has 4 block protection bit,
and added another flag for some flashes in which bp3 bit is not adjacent
to other bp bits.

Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
---
 drivers/mtd/spi-nor/core.c  | 62 ++++++++++++++++++++++++++++++++++---
 drivers/mtd/spi-nor/core.h  | 10 ++++++
 include/linux/mtd/spi-nor.h |  2 ++
 3 files changed, 69 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index e4ed8553aae8..842e2fabdb20 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1516,7 +1516,15 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 
 static u8 spi_nor_get_bp_mask(struct spi_nor *nor)
 {
-	return SR_BP2 | SR_BP1 | SR_BP0;
+	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
+
+	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
+		return mask | SR_BP3_BIT6;
+
+	if (nor->flags & SNOR_F_HAS_4BIT_BP)
+		return mask | SR_BP3;
+
+	return mask;
 }
 
 static u8 spi_nor_get_tb_mask(struct spi_nor *nor)
@@ -1532,7 +1540,8 @@ static int spi_nor_get_min_prot_length(struct spi_nor *nor)
 	int bp_slots, bp_slots_needed;
 	u8 mask = spi_nor_get_bp_mask(nor);
 
-	bp_slots = (mask >> SR_BP_SHIFT) + 1;
+	/* 2 ^ number_of_bp_bit slots available */
+	bp_slots = 1 << hweight8(mask);
 
 	/* Reserved one for "protect none" and one for "protect all". */
 	bp_slots = bp_slots - 2;
@@ -1553,7 +1562,12 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
 	int min_prot_len;
 	u8 mask = spi_nor_get_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_tb_mask(nor);
-	u8 bp = (sr & mask) >> SR_BP_SHIFT;
+	u8 bp, val = sr & mask;
+
+	if (val & SR_BP3_BIT6)
+		val = (val & ~SR_BP3_BIT6) | SR_BP3;
+
+	bp = val >> SR_BP_SHIFT;
 
 	if (!bp) {
 		/* No protection */
@@ -1611,7 +1625,7 @@ static int spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
 
 /*
  * Lock a region of the flash. Compatible with ST Micro and similar flash.
- * Supports the block protection bits BP{0,1,2} in the status register
+ * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status register
  * (SR). Does not support these features found in newer SR bitfields:
  *   - SEC: sector/block protect - only handle SEC=0 (block protect)
  *   - CMP: complement protect - only support CMP=0 (range is not complemented)
@@ -1619,7 +1633,7 @@ static int spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
  * Support for the following is provided conditionally for some flash:
  *   - TB: top/bottom protect
  *
- * Sample table portion for 8MB flash (Winbond w25q64fw):
+ * Sample table portion for 8MB flash (Winbond w25q64fw / BP0-2):
  *
  *   SEC  |  TB   |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected Portion
  *  --------------------------------------------------------------------------
@@ -1639,6 +1653,32 @@ static int spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
  *    0   |   1   |   1   |   0   |   1   |  2 MB         | Lower 1/4
  *    0   |   1   |   1   |   1   |   0   |  4 MB         | Lower 1/2
  *
+ * Sample table portion for 64MB flash (Micron n25q512ax3 / BP0-3):
+ *
+ *   TB   |  BP3  |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected Portion
+ *  --------------------------------------------------------------------------
+ *    0   |   0   |   0   |   0   |   0   |  NONE         | NONE
+ *    0   |   0   |   0   |   0   |   1   |   64 KB       | Upper 1/1024
+ *    0   |   0   |   0   |   1   |   0   |  128 KB       | Upper 1/512
+ *    0   |   0   |   0   |   1   |   1   |  256 KB       | Upper 1/256
+ *   ...
+ *    0   |   1   |   0   |   0   |   1   |  16 MB        | Upper 1/4
+ *    0   |   1   |   0   |   1   |   0   |  32 MB        | Upper 1/2
+ *    0   |   1   |   0   |   1   |   1   |  64 MB        | ALL
+ *    0   |   1   |   1   |   0   |   0   |  64 MB        | ALL
+ *   ...
+ *  ------|-------|-------|-------|-------|---------------|-------------------
+ *    1   |   0   |   0   |   0   |   0   |   NONE        | NONE
+ *    1   |   0   |   0   |   0   |   1   |   64 KB       | Lower 1/1024
+ *    1   |   0   |   0   |   1   |   0   |  128 KB       | Lower 1/512
+ *    1   |   0   |   0   |   1   |   1   |  256 KB       | Lower 1/256
+ *   ...
+ *    1   |   1   |   0   |   0   |   1   |  16 MB        | Lower 1/4
+ *    1   |   1   |   0   |   1   |   0   |  32 MB        | Lower 1/2
+ *    1   |   1   |   0   |   1   |   1   |  64 MB        | ALL
+ *    1   |   1   |   1   |   0   |   0   |  64 MB        | ALL
+ *   ...
+ *
  * Returns negative on errors, 0 on success.
  */
 static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
@@ -1690,6 +1730,9 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 		min_prot_len = spi_nor_get_min_prot_length(nor);
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
 		val = pow << SR_BP_SHIFT;
+
+		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
+			val = (val & ~SR_BP3) | SR_BP3_BIT6;
 	}
 
 	if (val & ~mask)
@@ -1772,6 +1815,9 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
 		val = pow << SR_BP_SHIFT;
 
+		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
+			val = (val & ~SR_BP3) | SR_BP3_BIT6;
+
 		/* Some power-of-two sizes are not supported */
 		if (val & ~mask)
 			return -EINVAL;
@@ -3131,6 +3177,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (info->flags & USE_CLSR)
 		nor->flags |= SNOR_F_USE_CLSR;
 
+	if (info->flags & SPI_NOR_4BIT_BP) {
+		nor->flags |= SNOR_F_HAS_4BIT_BP;
+		if (info->flags & SPI_NOR_BP3_SR_BIT6)
+			nor->flags |= SNOR_F_HAS_SR_BP3_BIT6;
+	}
+
 	if (info->flags & SPI_NOR_NO_ERASE)
 		mtd->flags |= MTD_NO_ERASE;
 
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 3ce826b35ad1..6f2f6b27173f 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -24,6 +24,8 @@ enum spi_nor_option_flags {
 	SNOR_F_HAS_16BIT_SR	= BIT(9),
 	SNOR_F_NO_READ_CR	= BIT(10),
 	SNOR_F_HAS_SR_TB_BIT6	= BIT(11),
+	SNOR_F_HAS_4BIT_BP      = BIT(12),
+	SNOR_F_HAS_SR_BP3_BIT6  = BIT(13),
 };
 
 struct spi_nor_read_command {
@@ -301,6 +303,14 @@ struct flash_info {
 					 * status register. Must be used with
 					 * SPI_NOR_HAS_TB.
 					 */
+#define SPI_NOR_4BIT_BP		BIT(17) /*
+					 * Flash SR has 4 bit fields (BP0-3)
+					 * for block protection.
+					 */
+#define SPI_NOR_BP3_SR_BIT6	BIT(18) /*
+					 * BP3 is bit 6 of status register.
+					 * Must be used with SPI_NOR_4BIT_BP.
+					 */
 
 	/* Part specific fixup hooks. */
 	const struct spi_nor_fixups *fixups;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index e656858b50a5..1e2af0ec1f03 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -111,7 +111,9 @@
 #define SR_BP0			BIT(2)	/* Block protect 0 */
 #define SR_BP1			BIT(3)	/* Block protect 1 */
 #define SR_BP2			BIT(4)	/* Block protect 2 */
+#define SR_BP3			BIT(5)	/* Block protect 3 */
 #define SR_TB_BIT5		BIT(5)	/* Top/Bottom protect */
+#define SR_BP3_BIT6		BIT(6)	/* Block protect 3 */
 #define SR_TB_BIT6		BIT(6)	/* Top/Bottom protect */
 #define SR_SRWD			BIT(7)	/* SR write protect */
 /* Spansion/Cypress specific status bits */
-- 
2.17.1


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Re: [PATCH v2 2/3] mtd: spi-nor: add 4bit block protection support

[Michael Walle]

Hi Jungseung,

Am 2020-03-18 13:06, schrieb Jungseung Lee:
> Currently, we are supporting block protection only for flash chips with
> 3 block protection bits in the SR register.
> 
> This patch enables block protection support for flashes with 4 block
> protection bits(bp0-3).
> 
> Added a flag to inform that this flash has 4 block protection bit,
> and added another flag for some flashes in which bp3 bit is not 
> adjacent
> to other bp bits.
> 
> Signed-off-by: Jungseung Lee <js07.lee@samsung.com>

Please add a changelog if you're doing a new patch version. This will
greatly ease the review.


> ---
>  drivers/mtd/spi-nor/core.c  | 62 ++++++++++++++++++++++++++++++++++---
>  drivers/mtd/spi-nor/core.h  | 10 ++++++
>  include/linux/mtd/spi-nor.h |  2 ++
>  3 files changed, 69 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index e4ed8553aae8..842e2fabdb20 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1516,7 +1516,15 @@ static int spi_nor_erase(struct mtd_info *mtd,
> struct erase_info *instr)
> 
>  static u8 spi_nor_get_bp_mask(struct spi_nor *nor)
>  {
> -	return SR_BP2 | SR_BP1 | SR_BP0;
> +	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> +
> +	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
> +		return mask | SR_BP3_BIT6;
> +
> +	if (nor->flags & SNOR_F_HAS_4BIT_BP)
> +		return mask | SR_BP3;
> +
> +	return mask;
>  }
> 
>  static u8 spi_nor_get_tb_mask(struct spi_nor *nor)
> @@ -1532,7 +1540,8 @@ static int spi_nor_get_min_prot_length(struct
> spi_nor *nor)
>  	int bp_slots, bp_slots_needed;
>  	u8 mask = spi_nor_get_bp_mask(nor);
> 
> -	bp_slots = (mask >> SR_BP_SHIFT) + 1;
> +	/* 2 ^ number_of_bp_bit slots available */
> +	bp_slots = 1 << hweight8(mask);
> 
>  	/* Reserved one for "protect none" and one for "protect all". */
>  	bp_slots = bp_slots - 2;
> @@ -1553,7 +1562,12 @@ static void spi_nor_get_locked_range_sr(struct
> spi_nor *nor, u8 sr, loff_t *ofs,
>  	int min_prot_len;
>  	u8 mask = spi_nor_get_bp_mask(nor);
>  	u8 tb_mask = spi_nor_get_tb_mask(nor);
> -	u8 bp = (sr & mask) >> SR_BP_SHIFT;
> +	u8 bp, val = sr & mask;
> +


you could add a comment here. It is not obvious why one don't need
to check nor->flags & SNOR_F_HAS_SR_BP3_BIT6. Ie. it is already
masked with mask retrieved from spi_nor_get_bp_mask() which makes
sure the SR_BP3_BIT6 may only be set if nor->flags contains that
specific flag. Or just be explicit and do

if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)

I'd prefer the latter because
  (1) its the same as you've done it below
  (2) its easier to understand in the future

That being said. Nice work! So if you do a respin with that you
can add:
Reviewed-by: Michael Walle <michael@walle.cc>

Tested with a MX25U3232F (no upstream support yet).

Tested-by: Michael Walle <michael@walle.cc>

> +	if (val & SR_BP3_BIT6)
> +		val = (val & ~SR_BP3_BIT6) | SR_BP3;
> +
> +	bp = val >> SR_BP_SHIFT;
> 
>  	if (!bp) {
>  		/* No protection */
> @@ -1611,7 +1625,7 @@ static int spi_nor_is_unlocked_sr(struct spi_nor
> *nor, loff_t ofs, uint64_t len,
> 
>  /*
>   * Lock a region of the flash. Compatible with ST Micro and similar 
> flash.
> - * Supports the block protection bits BP{0,1,2} in the status register
> + * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the
> status register
>   * (SR). Does not support these features found in newer SR bitfields:
>   *   - SEC: sector/block protect - only handle SEC=0 (block protect)
>   *   - CMP: complement protect - only support CMP=0 (range is not 
> complemented)
> @@ -1619,7 +1633,7 @@ static int spi_nor_is_unlocked_sr(struct spi_nor
> *nor, loff_t ofs, uint64_t len,
>   * Support for the following is provided conditionally for some flash:
>   *   - TB: top/bottom protect
>   *
> - * Sample table portion for 8MB flash (Winbond w25q64fw):
> + * Sample table portion for 8MB flash (Winbond w25q64fw / BP0-2):
>   *
>   *   SEC  |  TB   |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected 
> Portion
>   *  
> --------------------------------------------------------------------------
> @@ -1639,6 +1653,32 @@ static int spi_nor_is_unlocked_sr(struct
> spi_nor *nor, loff_t ofs, uint64_t len,
>   *    0   |   1   |   1   |   0   |   1   |  2 MB         | Lower 1/4
>   *    0   |   1   |   1   |   1   |   0   |  4 MB         | Lower 1/2
>   *
> + * Sample table portion for 64MB flash (Micron n25q512ax3 / BP0-3):
> + *
> + *   TB   |  BP3  |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected 
> Portion
> + *  
> --------------------------------------------------------------------------
> + *    0   |   0   |   0   |   0   |   0   |  NONE         | NONE
> + *    0   |   0   |   0   |   0   |   1   |   64 KB       | Upper 
> 1/1024
> + *    0   |   0   |   0   |   1   |   0   |  128 KB       | Upper 
> 1/512
> + *    0   |   0   |   0   |   1   |   1   |  256 KB       | Upper 
> 1/256
> + *   ...
> + *    0   |   1   |   0   |   0   |   1   |  16 MB        | Upper 1/4
> + *    0   |   1   |   0   |   1   |   0   |  32 MB        | Upper 1/2
> + *    0   |   1   |   0   |   1   |   1   |  64 MB        | ALL
> + *    0   |   1   |   1   |   0   |   0   |  64 MB        | ALL
> + *   ...
> + *  
> ------|-------|-------|-------|-------|---------------|-------------------
> + *    1   |   0   |   0   |   0   |   0   |   NONE        | NONE
> + *    1   |   0   |   0   |   0   |   1   |   64 KB       | Lower 
> 1/1024
> + *    1   |   0   |   0   |   1   |   0   |  128 KB       | Lower 
> 1/512
> + *    1   |   0   |   0   |   1   |   1   |  256 KB       | Lower 
> 1/256
> + *   ...
> + *    1   |   1   |   0   |   0   |   1   |  16 MB        | Lower 1/4
> + *    1   |   1   |   0   |   1   |   0   |  32 MB        | Lower 1/2
> + *    1   |   1   |   0   |   1   |   1   |  64 MB        | ALL
> + *    1   |   1   |   1   |   0   |   0   |  64 MB        | ALL
> + *   ...
> + *
>   * Returns negative on errors, 0 on success.
>   */
>  static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t 
> len)
> @@ -1690,6 +1730,9 @@ static int spi_nor_sr_lock(struct spi_nor *nor,
> loff_t ofs, uint64_t len)
>  		min_prot_len = spi_nor_get_min_prot_length(nor);
>  		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
>  		val = pow << SR_BP_SHIFT;
> +
> +		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
> +			val = (val & ~SR_BP3) | SR_BP3_BIT6;
>  	}
> 
>  	if (val & ~mask)
> @@ -1772,6 +1815,9 @@ static int spi_nor_sr_unlock(struct spi_nor
> *nor, loff_t ofs, uint64_t len)
>  		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
>  		val = pow << SR_BP_SHIFT;
> 
> +		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
> +			val = (val & ~SR_BP3) | SR_BP3_BIT6;
> +
>  		/* Some power-of-two sizes are not supported */
>  		if (val & ~mask)
>  			return -EINVAL;
> @@ -3131,6 +3177,12 @@ int spi_nor_scan(struct spi_nor *nor, const char 
> *name,
>  	if (info->flags & USE_CLSR)
>  		nor->flags |= SNOR_F_USE_CLSR;
> 
> +	if (info->flags & SPI_NOR_4BIT_BP) {
> +		nor->flags |= SNOR_F_HAS_4BIT_BP;
> +		if (info->flags & SPI_NOR_BP3_SR_BIT6)
> +			nor->flags |= SNOR_F_HAS_SR_BP3_BIT6;
> +	}
> +
>  	if (info->flags & SPI_NOR_NO_ERASE)
>  		mtd->flags |= MTD_NO_ERASE;
> 
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 3ce826b35ad1..6f2f6b27173f 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -24,6 +24,8 @@ enum spi_nor_option_flags {
>  	SNOR_F_HAS_16BIT_SR	= BIT(9),
>  	SNOR_F_NO_READ_CR	= BIT(10),
>  	SNOR_F_HAS_SR_TB_BIT6	= BIT(11),
> +	SNOR_F_HAS_4BIT_BP      = BIT(12),
> +	SNOR_F_HAS_SR_BP3_BIT6  = BIT(13),
>  };
> 
>  struct spi_nor_read_command {
> @@ -301,6 +303,14 @@ struct flash_info {
>  					 * status register. Must be used with
>  					 * SPI_NOR_HAS_TB.
>  					 */
> +#define SPI_NOR_4BIT_BP		BIT(17) /*
> +					 * Flash SR has 4 bit fields (BP0-3)
> +					 * for block protection.
> +					 */
> +#define SPI_NOR_BP3_SR_BIT6	BIT(18) /*
> +					 * BP3 is bit 6 of status register.
> +					 * Must be used with SPI_NOR_4BIT_BP.
> +					 */
> 
>  	/* Part specific fixup hooks. */
>  	const struct spi_nor_fixups *fixups;
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index e656858b50a5..1e2af0ec1f03 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -111,7 +111,9 @@
>  #define SR_BP0			BIT(2)	/* Block protect 0 */
>  #define SR_BP1			BIT(3)	/* Block protect 1 */
>  #define SR_BP2			BIT(4)	/* Block protect 2 */
> +#define SR_BP3			BIT(5)	/* Block protect 3 */
>  #define SR_TB_BIT5		BIT(5)	/* Top/Bottom protect */
> +#define SR_BP3_BIT6		BIT(6)	/* Block protect 3 */
>  #define SR_TB_BIT6		BIT(6)	/* Top/Bottom protect */
>  #define SR_SRWD			BIT(7)	/* SR write protect */
>  /* Spansion/Cypress specific status bits */

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[PATCH v2 3/3] mtd: spi-nor: support lock/unlock for a few Micron chips

[Jungseung Lee]

Some Micron models are known to have lock/unlock support,
and that also support 4bit block protection (bp0-3).

This patch support lock/unlock feature on the flashes.
Tested on n25q512ax3. The other is modified following the datasheet.

Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
---
 drivers/mtd/spi-nor/micron-st.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/micron-st.c b/drivers/mtd/spi-nor/micron-st.c
index 3874a62d8b47..6c034b9718e2 100644
--- a/drivers/mtd/spi-nor/micron-st.c
+++ b/drivers/mtd/spi-nor/micron-st.c
@@ -47,12 +47,16 @@ static const struct flash_info st_parts[] = {
 			       SECT_4K | USE_FSR | SPI_NOR_DUAL_READ |
 			       SPI_NOR_QUAD_READ | SPI_NOR_4B_OPCODES) },
 	{ "n25q512ax3",  INFO(0x20ba20, 0, 64 * 1024, 1024,
-			      SECT_4K | USE_FSR | SPI_NOR_QUAD_READ) },
+			      SECT_4K | USE_FSR | SPI_NOR_QUAD_READ |
+			      SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB |
+			      SPI_NOR_4BIT_BP | SPI_NOR_BP3_SR_BIT6) },
 	{ "mt25qu512a",  INFO6(0x20bb20, 0x104400, 64 * 1024, 1024,
 			       SECT_4K | USE_FSR | SPI_NOR_DUAL_READ |
 			       SPI_NOR_QUAD_READ | SPI_NOR_4B_OPCODES) },
 	{ "n25q512a",    INFO(0x20bb20, 0, 64 * 1024, 1024,
-			      SECT_4K | USE_FSR | SPI_NOR_QUAD_READ) },
+			      SECT_4K | USE_FSR | SPI_NOR_QUAD_READ |
+			      SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB |
+			      SPI_NOR_4BIT_BP | SPI_NOR_BP3_SR_BIT6) },
 	{ "n25q00",      INFO(0x20ba21, 0, 64 * 1024, 2048,
 			      SECT_4K | USE_FSR | SPI_NOR_QUAD_READ |
 			      NO_CHIP_ERASE) },
-- 
2.17.1


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Re: [PATCH v2 1/3] mtd: spi-nor: reimplement block protection handling

[Michael Walle]

Am 2020-03-18 13:06, schrieb Jungseung Lee:
> The current mainline locking was restricted and could only be applied
> to flashes that has 3 block protection bit and fixed locking ratio.
> 
> A new method of normalization was reached at the end of the discussion 
> [1].
> 
>     (1) - if bp slot is insufficient.
>     (2) - if bp slot is sufficient.
> 
>     if (bp_slots_needed > bp_slots)    // (1)
>         min_prot_length = sector_size << (bp_slots_needed - bp_slots);
>     else                               // (2)
>         min_prot_length = sector_size;
> 
> This patch changes logic to handle block protection based on 
> min_prot_length.
> It is suitable for the overall flashes with exception of some corner 
> case
> and easy to extend and apply for the case of 2bit or 4bit block 
> protection.
> 
> [1] 
> http://lists.infradead.org/pipermail/linux-mtd/2020-February/093934.html
> 
> Signed-off-by: Jungseung Lee <js07.lee@samsung.com>

Reviewed-by: Michael Walle <michael@walle.cc>

Tested with a W25Q32JW-IM.

Tested-by: Michael Walle <michael@walle.cc>

> ---
>  drivers/mtd/spi-nor/core.c | 110 ++++++++++++++++++++++---------------
>  1 file changed, 66 insertions(+), 44 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 877557dbda7f..e4ed8553aae8 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1514,29 +1514,64 @@ static int spi_nor_erase(struct mtd_info *mtd,
> struct erase_info *instr)
>  	return ret;
>  }
> 
> +static u8 spi_nor_get_bp_mask(struct spi_nor *nor)
> +{
> +	return SR_BP2 | SR_BP1 | SR_BP0;
> +}
> +
> +static u8 spi_nor_get_tb_mask(struct spi_nor *nor)
> +{
> +	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> +		return SR_TB_BIT6;
> +	else
> +		return SR_TB_BIT5;
> +}
> +
> +static int spi_nor_get_min_prot_length(struct spi_nor *nor)
> +{
> +	int bp_slots, bp_slots_needed;
> +	u8 mask = spi_nor_get_bp_mask(nor);
> +
> +	bp_slots = (mask >> SR_BP_SHIFT) + 1;
> +
> +	/* Reserved one for "protect none" and one for "protect all". */
> +	bp_slots = bp_slots - 2;
> +
> +	bp_slots_needed = ilog2(nor->info->n_sectors);
> +
> +	if (bp_slots_needed > bp_slots)
> +		return nor->info->sector_size <<
> +			(bp_slots_needed - bp_slots);
> +	else
> +		return nor->info->sector_size;
> +}
> +
>  static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr,
> loff_t *ofs,
>  					uint64_t *len)
>  {
>  	struct mtd_info *mtd = &nor->mtd;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> -	u8 tb_mask = SR_TB_BIT5;
> -	int pow;
> -
> -	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> -		tb_mask = SR_TB_BIT6;
> +	int min_prot_len;
> +	u8 mask = spi_nor_get_bp_mask(nor);
> +	u8 tb_mask = spi_nor_get_tb_mask(nor);
> +	u8 bp = (sr & mask) >> SR_BP_SHIFT;
> 
> -	if (!(sr & mask)) {
> +	if (!bp) {
>  		/* No protection */
>  		*ofs = 0;
>  		*len = 0;
> -	} else {
> -		pow = ((sr & mask) ^ mask) >> SR_BP_SHIFT;
> -		*len = mtd->size >> pow;
> -		if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
> -			*ofs = 0;
> -		else
> -			*ofs = mtd->size - *len;
> +		return;
>  	}
> +
> +	min_prot_len = spi_nor_get_min_prot_length(nor);
> +	*len = min_prot_len << (bp - 1);
> +
> +	if (*len > mtd->size)
> +		*len = mtd->size;
> +
> +	if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
> +		*ofs = 0;
> +	else
> +		*ofs = mtd->size - *len;
>  }
> 
>  /*
> @@ -1610,8 +1645,9 @@ static int spi_nor_sr_lock(struct spi_nor *nor,
> loff_t ofs, uint64_t len)
>  {
>  	struct mtd_info *mtd = &nor->mtd;
>  	int ret, status_old, status_new;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> -	u8 tb_mask = SR_TB_BIT5;
> +	int min_prot_len;
> +	u8 mask = spi_nor_get_bp_mask(nor);
> +	u8 tb_mask = spi_nor_get_tb_mask(nor);
>  	u8 pow, val;
>  	loff_t lock_len;
>  	bool can_be_top = true, can_be_bottom = nor->flags & 
> SNOR_F_HAS_SR_TB;
> @@ -1648,20 +1684,14 @@ static int spi_nor_sr_lock(struct spi_nor
> *nor, loff_t ofs, uint64_t len)
>  	else
>  		lock_len = ofs + len;
> 
> -	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> -		tb_mask = SR_TB_BIT6;
> +	if (lock_len == mtd->size) {
> +		val = mask; /* fully locked */
> +	} else {
> +		min_prot_len = spi_nor_get_min_prot_length(nor);
> +		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
> +		val = pow << SR_BP_SHIFT;
> +	}
> 
> -	/*
> -	 * Need smallest pow such that:
> -	 *
> -	 *   1 / (2^pow) <= (len / size)
> -	 *
> -	 * so (assuming power-of-2 size) we do:
> -	 *
> -	 *   pow = ceil(log2(size / len)) = log2(size) - floor(log2(len))
> -	 */
> -	pow = ilog2(mtd->size) - ilog2(lock_len);
> -	val = mask - (pow << SR_BP_SHIFT);
>  	if (val & ~mask)
>  		return -EINVAL;
>  	/* Don't "lock" with no region! */
> @@ -1696,8 +1726,9 @@ static int spi_nor_sr_unlock(struct spi_nor
> *nor, loff_t ofs, uint64_t len)
>  {
>  	struct mtd_info *mtd = &nor->mtd;
>  	int ret, status_old, status_new;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> -	u8 tb_mask = SR_TB_BIT5;
> +	int min_prot_len;
> +	u8 mask = spi_nor_get_bp_mask(nor);
> +	u8 tb_mask = spi_nor_get_tb_mask(nor);
>  	u8 pow, val;
>  	loff_t lock_len;
>  	bool can_be_top = true, can_be_bottom = nor->flags & 
> SNOR_F_HAS_SR_TB;
> @@ -1734,22 +1765,13 @@ static int spi_nor_sr_unlock(struct spi_nor
> *nor, loff_t ofs, uint64_t len)
>  	else
>  		lock_len = ofs;
> 
> -	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> -		tb_mask = SR_TB_BIT6;
> -	/*
> -	 * Need largest pow such that:
> -	 *
> -	 *   1 / (2^pow) >= (len / size)
> -	 *
> -	 * so (assuming power-of-2 size) we do:
> -	 *
> -	 *   pow = floor(log2(size / len)) = log2(size) - ceil(log2(len))
> -	 */
> -	pow = ilog2(mtd->size) - order_base_2(lock_len);
>  	if (lock_len == 0) {
>  		val = 0; /* fully unlocked */
>  	} else {
> -		val = mask - (pow << SR_BP_SHIFT);
> +		min_prot_len = spi_nor_get_min_prot_length(nor);
> +		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
> +		val = pow << SR_BP_SHIFT;
> +
>  		/* Some power-of-two sizes are not supported */
>  		if (val & ~mask)
>  			return -EINVAL;

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