Re: [PATCH v3 4/5] mtd: spi-nor: Add SR 4bit block protection support

[Jungseung Lee <js07.lee@xxxxxxxxxxx>]

Hi,

On Mon, 2020-03-23 at 09:24 +0000, Tudor.Ambarus@xxxxxxxxxxxxx wrote:
> From: Jungseung Lee <js07.lee@xxxxxxxxxxx>
> 
> Currently, we are supporting block protection only for flash chips
> with
> 3 block protection bits (BP0-2) in the SR register.
> 
> Enable block protection support for flashes with 4 block protection
> bits
> (BP0-3).
> 
> Add a flash_info flag for flashes that describe 4 block protection
> bits.
> Add another flash_info flag for flashes in which BP3 bit is not
> adjacent
> to the BP0-2 bits.
> 
> Signed-off-by: Jungseung Lee <js07.lee@xxxxxxxxxxx>
> Reviewed-by: Michael Walle <michael@xxxxxxxx>
> Tested-by: Michael Walle <michael@xxxxxxxx>
> [ta:
> - introduce spi_nor_get_sr_bp_mask(), spi_nor_get_sr_tb_mask()
> - drop Micron n25q512ax3 / BP0-3) boilerplate description
> - be explicit in spi_nor_get_locked_range_sr aboyt SR_BP3 as Michael
> suggested,
> - amend commit description]
> Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
> ---
>  drivers/mtd/spi-nor/core.c  | 66 +++++++++++++++++++++++++++------
> ----
>  drivers/mtd/spi-nor/core.h  | 10 ++++++
>  include/linux/mtd/spi-nor.h |  2 ++
>  3 files changed, 60 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index c0d186f417d8..b70c0b2e0958 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1514,13 +1514,34 @@ static int spi_nor_erase(struct mtd_info
> *mtd, struct erase_info *instr)
>  	return ret;
>  }
>  
> +static u8 spi_nor_get_sr_bp_mask(struct spi_nor *nor)
> +{
> +	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_sr_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 u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
>  {
>  	unsigned int bp_slots, bp_slots_needed;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> +	u8 mask = spi_nor_get_sr_bp_mask(nor);
>  
>  	/* Reserved one for "protect none" and one for "protect all".
> */
> -	bp_slots = (mask >> SR_BP_SHIFT) + 1 - 2;
> +	bp_slots = (1 << hweight8(mask)) - 2;
>  	bp_slots_needed = ilog2(nor->info->n_sectors);
>  
>  	if (bp_slots_needed > bp_slots)
> @@ -1535,12 +1556,14 @@ static void
> spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
>  {
>  	struct mtd_info *mtd = &nor->mtd;
>  	u64 min_prot_len;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> -	u8 tb_mask = SR_TB_BIT5;
> -	u8 bp = (sr & mask) >> SR_BP_SHIFT;
> +	u8 mask = spi_nor_get_sr_bp_mask(nor);
> +	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
> +	u8 bp, val = sr & mask;
>  
> -	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> -		tb_mask = SR_TB_BIT6;
> +	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
> +		val = (val & ~SR_BP3_BIT6) | SR_BP3;
> +
> +	bp = val >> SR_BP_SHIFT;
>  
>  	if (!bp) {
>  		/* No protection */
> @@ -1598,7 +1621,8 @@ 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)
> @@ -1633,8 +1657,8 @@ static int spi_nor_sr_lock(struct spi_nor *nor,
> loff_t ofs, uint64_t len)
>  	struct mtd_info *mtd = &nor->mtd;
>  	u64 min_prot_len;
>  	int ret, status_old, status_new;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> -	u8 tb_mask = SR_TB_BIT5;
> +	u8 mask = spi_nor_get_sr_bp_mask(nor);
> +	u8 tb_mask = spi_nor_get_sr_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;
> @@ -1671,9 +1695,6 @@ 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;
>  	} else {
> @@ -1681,6 +1702,9 @@ static int spi_nor_sr_lock(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;
> +
>  		if (val & ~mask)
>  			return -EINVAL;
>  
> @@ -1718,8 +1742,8 @@ static int spi_nor_sr_unlock(struct spi_nor
> *nor, loff_t ofs, uint64_t len)
>  	struct mtd_info *mtd = &nor->mtd;
>  	u64 min_prot_len;
>  	int ret, status_old, status_new;
> -	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> -	u8 tb_mask = SR_TB_BIT5;
> +	u8 mask = spi_nor_get_sr_bp_mask(nor);
> +	u8 tb_mask = spi_nor_get_sr_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;
> @@ -1756,9 +1780,6 @@ 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;
> -
>  	if (lock_len == 0) {
>  		val = 0; /* fully unlocked */
>  	} else {
> @@ -1766,6 +1787,9 @@ 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;
> @@ -3125,6 +3149,12 @@ 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 */

Tested with a n25q512ax3 (bp0-3) and w25q128 (bp0-2).
It passed all of my test cases.

Tested-by: Jungseung Lee <js07.lee@xxxxxxxxxxx>


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