RE: [PATCH v3 1/2] mtd: spi-nor: add support to non-uniform SFDP SPI NOR flash memories

[Yogesh Narayan Gaur <yogeshnarayan.gaur@xxxxxxx>]

Hi Tudor,

This patch is breaking the 1-4-4 Read protocol for the spansion flash "s25fl512s".

Without this patch read request command for Quad mode, 4-byte enable, is coming as 0xEC i.e. SPINOR_OP_READ_1_4_4_4B.
But after applying this patch, read request command for Quad mode is coming as 0x6C i.e. SPINOR_OP_READ_1_1_4_4B.

This flash also supports non-uniform erase.
Can you please check and provide some suggestion?

--
Regards
Yogesh Gaur

> -----Original Message-----
> From: linux-mtd [mailto:linux-mtd-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Tudor Ambarus
> Sent: Tuesday, September 11, 2018 9:10 PM
> To: marek.vasut@xxxxxxxxx; dwmw2@xxxxxxxxxxxxx;
> computersforpeace@xxxxxxxxx; boris.brezillon@xxxxxxxxxxx; richard@xxxxxx
> Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>; linux-
> kernel@xxxxxxxxxxxxxxx; nicolas.ferre@xxxxxxxxxxxxx;
> cyrille.pitchen@xxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; Cristian.Birsan@xxxxxxxxxxxxx
> Subject: [PATCH v3 1/2] mtd: spi-nor: add support to non-uniform SFDP SPI NOR
> flash memories
> 
> Based on Cyrille Pitchen's patch
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.or
> g%2Flkml%2F2017%2F3%2F22%2F935&amp;data=02%7C01%7Cyogeshnarayan.
> gaur%40nxp.com%7C3c782e52b7fd4a8b9af008d617fd5154%7C686ea1d3bc2b4
> c6fa92cd99c5c301635%7C0%7C0%7C636722774108718782&amp;sdata=szyc%
> 2FTumG6eYAmBd0oW3IL7v1yLh9E1SAZqL%2BCWczOA%3D&amp;reserved=0.
> 
> This patch is a transitional patch in introducing  the support of SFDP SPI
> memories with non-uniform erase sizes like Spansion s25fs512s.
> Non-uniform erase maps will be used later when initialized based on the SFDP
> data.
> 
> Introduce the memory erase map which splits the memory array into one or
> many erase regions. Each erase region supports up to 4 erase types, as defined
> by the JEDEC JESD216B (SFDP) specification.
> 
> To be backward compatible, the erase map of uniform SPI NOR flash memories
> is initialized so it contains only one erase region and this erase region supports
> only one erase command. Hence a single size is used to erase any sector/block
> of the memory.
> 
> Besides, since the algorithm used to erase sectors on non-uniform SPI NOR flash
> memories is quite expensive, when possible, the erase map is tuned to come
> back to the uniform case.
> 
> The 'erase with the best command, move forward and repeat' approach was
> suggested by Cristian Birsan in a brainstorm session, so:
> 
> Suggested-by: Cristian Birsan <cristian.birsan@xxxxxxxxxxxxx>
> Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 594
> +++++++++++++++++++++++++++++++++++++++---
>  include/linux/mtd/spi-nor.h   | 107 ++++++++
>  2 files changed, 659 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c index
> dc8757e..4687345 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -18,6 +18,7 @@
>  #include <linux/math64.h>
>  #include <linux/sizes.h>
>  #include <linux/slab.h>
> +#include <linux/sort.h>
> 
>  #include <linux/mtd/mtd.h>
>  #include <linux/of_platform.h>
> @@ -261,6 +262,18 @@ static void spi_nor_set_4byte_opcodes(struct spi_nor
> *nor,
>  	nor->read_opcode = spi_nor_convert_3to4_read(nor->read_opcode);
>  	nor->program_opcode = spi_nor_convert_3to4_program(nor-
> >program_opcode);
>  	nor->erase_opcode = spi_nor_convert_3to4_erase(nor->erase_opcode);
> +
> +	if (!spi_nor_has_uniform_erase(nor)) {
> +		struct spi_nor_erase_map *map = &nor->erase_map;
> +		struct spi_nor_erase_type *erase;
> +		int i;
> +
> +		for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++) {
> +			erase = &map->erase_type[i];
> +			erase->opcode =
> +				spi_nor_convert_3to4_erase(erase->opcode);
> +		}
> +	}
>  }
> 
>  /* Enable/disable 4-byte addressing mode. */ @@ -499,6 +512,275 @@ static
> int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)  }
> 
>  /*
> + * spi_nor_div_by_erase_size() - calculate remainder and update new dividend
> + * @erase:	pointer to a structure that describes a SPI NOR erase type
> + * @dividend:	dividend value
> + * @remainder:	pointer to u32 remainder (will be updated)
> + *
> + * Returns two values: remainder and the new dividend  */ static u64
> +spi_nor_div_by_erase_size(const struct spi_nor_erase_type *erase,
> +				     u64 dividend, u32 *remainder)
> +{
> +	/* JEDEC JESD216B Standard imposes erase sizes to be power of 2. */
> +	*remainder = (u32)dividend & erase->size_mask;
> +	return dividend >> erase->size_shift;
> +}
> +
> +/*
> + * spi_nor_find_best_erase_type() - find the best erase type for the
> +given
> + * offset in the serial flash memory and the number of bytes to erase.
> +The
> + * region in which the address fits is expected to be provided.
> + * @map:	the erase map of the SPI NOR
> + * @region:	pointer to a structure that describes a SPI NOR erase region
> + * @addr:	offset in the serial flash memory
> + * @len:	number of bytes to erase
> + *
> + * Returns a pointer to the best fitted erase type, NULL otherwise.
> + */
> +static const struct spi_nor_erase_type *
> +spi_nor_find_best_erase_type(const struct spi_nor_erase_map *map,
> +			     const struct spi_nor_erase_region *region,
> +			     u64 addr, u32 len)
> +{
> +	const struct spi_nor_erase_type *erase;
> +	u32 rem;
> +	int i;
> +	u8 erase_mask = region->offset & SNOR_ERASE_TYPE_MASK;
> +
> +	/*
> +	 * Erase types are ordered by size, with the biggest erase type at
> +	 * index 0.
> +	 */
> +	for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
> +		/* Does the erase region support the tested erase type? */
> +		if (!(erase_mask & BIT(i)))
> +			continue;
> +
> +		erase = &map->erase_type[i];
> +
> +		/* Don't erase more than what the user has asked for. */
> +		if (erase->size > len)
> +			continue;
> +
> +		/* Alignment is not mandatory for overlaid regions */
> +		if (region->offset & SNOR_OVERLAID_REGION)
> +			return erase;
> +
> +		spi_nor_div_by_erase_size(erase, addr, &rem);
> +		if (rem)
> +			continue;
> +		else
> +			return erase;
> +	}
> +
> +	return NULL;
> +}
> +
> +/*
> + * spi_nor_region_next() - get the next spi nor region
> + * @region:	pointer to a structure that describes a SPI NOR erase region
> + *
> + * Returns the next spi nor region or NULL if last region.
> + */
> +static struct spi_nor_erase_region *
> +spi_nor_region_next(struct spi_nor_erase_region *region) {
> +	if (spi_nor_region_is_last(region))
> +		return NULL;
> +	region++;
> +	return region;
> +}
> +
> +/*
> + * spi_nor_find_erase_region() - find the region of the serial flash
> +memory in
> + * which the offset fits
> + * @map:	the erase map of the SPI NOR
> + * @addr:	offset in the serial flash memory
> + *
> + * Returns pointer to the spi_nor_erase_region struct, ERR_PTR(-errno)
> + * otherwise.
> + */
> +static struct spi_nor_erase_region *
> +spi_nor_find_erase_region(const struct spi_nor_erase_map *map, u64
> +addr) {
> +	struct spi_nor_erase_region *region = map->regions;
> +	u64 region_start = region->offset & ~SNOR_ERASE_FLAGS_MASK;
> +	u64 region_end = region_start + region->size;
> +
> +	while (addr < region_start || addr >= region_end) {
> +		region = spi_nor_region_next(region);
> +		if (!region)
> +			return ERR_PTR(-EINVAL);
> +
> +		region_start = region->offset & ~SNOR_ERASE_FLAGS_MASK;
> +		region_end = region_start + region->size;
> +	}
> +
> +	return region;
> +}
> +
> +/*
> + * spi_nor_init_erase_cmd() - initialize an erase command
> + * @region:	pointer to a structure that describes a SPI NOR erase region
> + * @erase:	pointer to a structure that describes a SPI NOR erase type
> + *
> + * Returns the pointer to the allocated erase command, ERR_PTR(-errno)
> + * otherwise.
> + */
> +static struct spi_nor_erase_command *
> +spi_nor_init_erase_cmd(const struct spi_nor_erase_region *region,
> +		       const struct spi_nor_erase_type *erase) {
> +	struct spi_nor_erase_command *cmd;
> +
> +	cmd = kmalloc(sizeof(*cmd), GFP_KERNEL);
> +	if (!cmd)
> +		return ERR_PTR(-ENOMEM);
> +
> +	INIT_LIST_HEAD(&cmd->list);
> +	cmd->opcode = erase->opcode;
> +	cmd->count = 1;
> +
> +	if (region->offset & SNOR_OVERLAID_REGION)
> +		cmd->size = region->size;
> +	else
> +		cmd->size = erase->size;
> +
> +	return cmd;
> +}
> +
> +/*
> + * spi_nor_destroy_erase_cmd_list() - destroy erase command list
> + * @erase_list:	list of erase commands
> + */
> +static void spi_nor_destroy_erase_cmd_list(struct list_head
> +*erase_list) {
> +	struct spi_nor_erase_command *cmd, *next;
> +
> +	list_for_each_entry_safe(cmd, next, erase_list, list) {
> +		list_del(&cmd->list);
> +		kfree(cmd);
> +	}
> +}
> +
> +/*
> + * spi_nor_init_erase_cmd_list() - initialize erase command list
> + * @nor:	pointer to a 'struct spi_nor'
> + * @erase_list:	list of erase commands to be executed once we validate that
> the
> + *		erase can be performed
> + * @addr:	offset in the serial flash memory
> + * @len:	number of bytes to erase
> + *
> + * Builds the list of best fitted erase commands and verifies if the
> +erase can
> + * be performed.
> + *
> + * Returns 0 on success, -errno otherwise.
> + */
> +static int spi_nor_init_erase_cmd_list(struct spi_nor *nor,
> +				       struct list_head *erase_list,
> +				       u64 addr, u32 len)
> +{
> +	const struct spi_nor_erase_map *map = &nor->erase_map;
> +	const struct spi_nor_erase_type *erase, *prev_erase = NULL;
> +	struct spi_nor_erase_region *region;
> +	struct spi_nor_erase_command *cmd = NULL;
> +	u64 region_end;
> +	int ret = -EINVAL;
> +
> +	region = spi_nor_find_erase_region(map, addr);
> +	if (IS_ERR(region))
> +		return PTR_ERR(region);
> +
> +	region_end = spi_nor_region_end(region);
> +
> +	while (len) {
> +		erase = spi_nor_find_best_erase_type(map, region, addr, len);
> +		if (!erase)
> +			goto destroy_erase_cmd_list;
> +
> +		if (prev_erase != erase ||
> +		    region->offset & SNOR_OVERLAID_REGION) {
> +			cmd = spi_nor_init_erase_cmd(region, erase);
> +			if (IS_ERR(cmd)) {
> +				ret = PTR_ERR(cmd);
> +				goto destroy_erase_cmd_list;
> +			}
> +
> +			list_add_tail(&cmd->list, erase_list);
> +		} else {
> +			cmd->count++;
> +		}
> +
> +		addr += cmd->size;
> +		len -= cmd->size;
> +
> +		if (len && addr >= region_end) {
> +			region = spi_nor_region_next(region);
> +			if (!region)
> +				goto destroy_erase_cmd_list;
> +			region_end = spi_nor_region_end(region);
> +		}
> +
> +		prev_erase = erase;
> +	}
> +
> +	return 0;
> +
> +destroy_erase_cmd_list:
> +	spi_nor_destroy_erase_cmd_list(erase_list);
> +	return ret;
> +}
> +
> +/*
> + * spi_nor_erase_multi_sectors() - perform a non-uniform erase
> + * @nor:	pointer to a 'struct spi_nor'
> + * @addr:	offset in the serial flash memory
> + * @len:	number of bytes to erase
> + *
> + * Build a list of best fitted erase commands and execute it once we
> + * validate that the erase can be performed.
> + *
> + * Returns 0 on success, -errno otherwise.
> + */
> +static int spi_nor_erase_multi_sectors(struct spi_nor *nor, u64 addr,
> +u32 len) {
> +	LIST_HEAD(erase_list);
> +	struct spi_nor_erase_command *cmd, *next;
> +	int ret;
> +
> +	ret = spi_nor_init_erase_cmd_list(nor, &erase_list, addr, len);
> +	if (ret)
> +		return ret;
> +
> +	list_for_each_entry_safe(cmd, next, &erase_list, list) {
> +		nor->erase_opcode = cmd->opcode;
> +		while (cmd->count) {
> +			write_enable(nor);
> +
> +			ret = spi_nor_erase_sector(nor, addr);
> +			if (ret)
> +				goto destroy_erase_cmd_list;
> +
> +			addr += cmd->size;
> +			cmd->count--;
> +
> +			ret = spi_nor_wait_till_ready(nor);
> +			if (ret)
> +				goto destroy_erase_cmd_list;
> +		}
> +		list_del(&cmd->list);
> +		kfree(cmd);
> +	}
> +
> +	return 0;
> +
> +destroy_erase_cmd_list:
> +	spi_nor_destroy_erase_cmd_list(&erase_list);
> +	return ret;
> +}
> +
> +/*
>   * Erase an address range on the nor chip.  The address range may extend
>   * one or more erase sectors.  Return an error is there is a problem erasing.
>   */
> @@ -512,9 +794,11 @@ static int spi_nor_erase(struct mtd_info *mtd, struct
> erase_info *instr)
>  	dev_dbg(nor->dev, "at 0x%llx, len %lld\n", (long long)instr->addr,
>  			(long long)instr->len);
> 
> -	div_u64_rem(instr->len, mtd->erasesize, &rem);
> -	if (rem)
> -		return -EINVAL;
> +	if (spi_nor_has_uniform_erase(nor)) {
> +		div_u64_rem(instr->len, mtd->erasesize, &rem);
> +		if (rem)
> +			return -EINVAL;
> +	}
> 
>  	addr = instr->addr;
>  	len = instr->len;
> @@ -553,7 +837,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct
> erase_info *instr)
>  	 */
> 
>  	/* "sector"-at-a-time erase */
> -	} else {
> +	} else if (spi_nor_has_uniform_erase(nor)) {
>  		while (len) {
>  			write_enable(nor);
> 
> @@ -568,6 +852,12 @@ static int spi_nor_erase(struct mtd_info *mtd, struct
> erase_info *instr)
>  			if (ret)
>  				goto erase_err;
>  		}
> +
> +	/* erase multiple sectors */
> +	} else {
> +		ret = spi_nor_erase_multi_sectors(nor, addr, len);
> +		if (ret)
> +			goto erase_err;
>  	}
> 
>  	write_disable(nor);
> @@ -2190,6 +2480,113 @@ static const struct sfdp_bfpt_erase
> sfdp_bfpt_erases[] = {
> 
>  static int spi_nor_hwcaps_read2cmd(u32 hwcaps);
> 
> +/*
> + * spi_nor_set_erase_type() - set a SPI NOR erase type
> + * @erase:	pointer to a structure that describes a SPI NOR erase type
> + * @size:	the size of the sector/block erased by the erase type
> + * @opcode:	the SPI command op code to erase the sector/block
> + */
> +static void spi_nor_set_erase_type(struct spi_nor_erase_type *erase,
> +				   u32 size, u8 opcode)
> +{
> +	erase->size = size;
> +	erase->opcode = opcode;
> +	/* JEDEC JESD216B Standard imposes erase sizes to be power of 2. */
> +	erase->size_shift = ffs(erase->size) - 1;
> +	erase->size_mask = (1 << erase->size_shift) - 1; }
> +
> +/*
> + * spi_nor_set_erase_settings_from_bfpt() - set erase type settings from BFPT
> + * @erase:	pointer to a structure that describes a SPI NOR erase type
> + * @size:	the size of the sector/block erased by the erase type
> + * @opcode:	the SPI command op code to erase the sector/block
> + * @i:		erase type index as sorted in the Basic Flash Parameter Table
> + *
> + * The supported Erase Types will be sorted at init in ascending order,
> +with
> + * the smallest Erase Type size being the first member in the
> +erase_type array
> + * of the spi_nor_erase_map structure. Save the Erase Type index as
> +sorted in
> + * the Basic Flash Parameter Table since it will be used later on to
> + * synchronize with the supported Erase Types defined in SFDP optional tables.
> + */
> +static void
> +spi_nor_set_erase_settings_from_bfpt(struct spi_nor_erase_type *erase,
> +				     u32 size, u8 opcode, u8 i)
> +{
> +	erase->idx = i;
> +	spi_nor_set_erase_type(erase, size, opcode); }
> +
> +/* spi_nor_map_cmp_erase_type() - compare the map's erase types by size
> + * @l:	member in the left half of the map's erase_type array
> + * @r:	member in the right half of the map's erase_type array
> + *
> + * Comparison function used in the sort() call to sort in ascending
> +order the
> + * map's erase types, the smallest erase type size being the first
> +member in the
> + * sorted erase_type array.
> + */
> +static int spi_nor_map_cmp_erase_type(const void *l, const void *r) {
> +	const struct spi_nor_erase_type *left = l, *right = r;
> +
> +	return left->size - right->size;
> +}
> +
> +/*
> + * spi_nor_regions_sort_erase_types() - sort erase types in each region
> + * @map:	the erase map of the SPI NOR
> + *
> + * Function assumes that the erase types defined in the erase map are
> +already
> + * sorted in ascending order, with the smallest erase type size being
> +the first
> + * member in the erase_type array. It replicates the sort done for the
> +map's
> + * erase types. Each region's erase bitmask will indicate which erase
> +types are
> + * supported from the sorted erase types defined in the erase map.
> + * Sort the all region's erase type at init in order to speed up the
> +process of
> + * finding the best erase command at runtime.
> + */
> +static void spi_nor_regions_sort_erase_types(struct spi_nor_erase_map
> +*map) {
> +	struct spi_nor_erase_region *region = map->regions;
> +	struct spi_nor_erase_type *erase_type = map->erase_type;
> +	int i;
> +	u8 region_erase_mask, sorted_erase_mask;
> +
> +	while (region) {
> +		region_erase_mask = region->offset &
> SNOR_ERASE_TYPE_MASK;
> +
> +		/* Replicate the sort done for the map's erase types. */
> +		sorted_erase_mask = 0;
> +		for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++)
> +			if (erase_type[i].size &&
> +			    region_erase_mask & BIT(erase_type[i].idx))
> +				sorted_erase_mask |= BIT(i);
> +
> +		/* Overwrite erase mask. */
> +		region->offset = (region->offset & ~SNOR_ERASE_TYPE_MASK)
> |
> +				 sorted_erase_mask;
> +
> +		region = spi_nor_region_next(region);
> +	}
> +}
> +
> +/*
> + *spi_nor_init_uniform_erase_map() - Initialize uniform erase map
> + * @map:		the erase map of the SPI NOR
> + * @erase_mask:		bitmask encoding erase types that can erase
> the entire
> + *			flash memory
> + * @flash_size:		the spi nor flash memory size
> + */
> +static void spi_nor_init_uniform_erase_map(struct spi_nor_erase_map *map,
> +					   u8 erase_mask, u64 flash_size)
> +{
> +	/* Offset 0 with erase_mask and SNOR_LAST_REGION bit set */
> +	map->uniform_region.offset = (erase_mask &
> SNOR_ERASE_TYPE_MASK) |
> +				     SNOR_LAST_REGION;
> +	map->uniform_region.size = flash_size;
> +	map->regions = &map->uniform_region;
> +	map->uniform_erase_type = erase_mask;
> +}
> +
>  /**
>   * spi_nor_parse_bfpt() - read and parse the Basic Flash Parameter Table.
>   * @nor:		pointer to a 'struct spi_nor'
> @@ -2224,12 +2621,14 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
>  			      const struct sfdp_parameter_header *bfpt_header,
>  			      struct spi_nor_flash_parameter *params)  {
> -	struct mtd_info *mtd = &nor->mtd;
> +	struct spi_nor_erase_map *map = &nor->erase_map;
> +	struct spi_nor_erase_type *erase_type = map->erase_type;
>  	struct sfdp_bfpt bfpt;
>  	size_t len;
>  	int i, cmd, err;
>  	u32 addr;
>  	u16 half;
> +	u8 erase_mask;
> 
>  	/* JESD216 Basic Flash Parameter Table length is at least 9 DWORDs. */
>  	if (bfpt_header->length < BFPT_DWORD_MAX_JESD216) @@ -2298,7
> +2697,12 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
>  		spi_nor_set_read_settings_from_bfpt(read, half, rd->proto);
>  	}
> 
> -	/* Sector Erase settings. */
> +	/*
> +	 * Sector Erase settings. Reinitialize the uniform erase map using the
> +	 * Erase Types defined in the bfpt table.
> +	 */
> +	erase_mask = 0;
> +	memset(&nor->erase_map, 0, sizeof(nor->erase_map));
>  	for (i = 0; i < ARRAY_SIZE(sfdp_bfpt_erases); i++) {
>  		const struct sfdp_bfpt_erase *er = &sfdp_bfpt_erases[i];
>  		u32 erasesize;
> @@ -2313,18 +2717,25 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
> 
>  		erasesize = 1U << erasesize;
>  		opcode = (half >> 8) & 0xff;
> -#ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
> -		if (erasesize == SZ_4K) {
> -			nor->erase_opcode = opcode;
> -			mtd->erasesize = erasesize;
> -			break;
> -		}
> -#endif
> -		if (!mtd->erasesize || mtd->erasesize < erasesize) {
> -			nor->erase_opcode = opcode;
> -			mtd->erasesize = erasesize;
> -		}
> +		erase_mask |= BIT(i);
> +		spi_nor_set_erase_settings_from_bfpt(&erase_type[i],
> erasesize,
> +						     opcode, i);
>  	}
> +	spi_nor_init_uniform_erase_map(map, erase_mask, params->size);
> +	/*
> +	 * Sort all the map's Erase Types in ascending order with the smallest
> +	 * erase size being the first member in the erase_type array.
> +	 */
> +	sort(erase_type, SNOR_ERASE_TYPE_MAX, sizeof(erase_type[0]),
> +	     spi_nor_map_cmp_erase_type, NULL);
> +	/*
> +	 * Sort the erase types in the uniform region in order to update the
> +	 * uniform_erase_type bitmask. The bitmask will be used later on when
> +	 * selecting the uniform erase.
> +	 */
> +	spi_nor_regions_sort_erase_types(map);
> +	map->uniform_erase_type = map->uniform_region.offset &
> +				  SNOR_ERASE_TYPE_MASK;
> 
>  	/* Stop here if not JESD216 rev A or later. */
>  	if (bfpt_header->length < BFPT_DWORD_MAX) @@ -2480,6 +2891,9
> @@ static int spi_nor_init_params(struct spi_nor *nor,
>  			       const struct flash_info *info,
>  			       struct spi_nor_flash_parameter *params)  {
> +	struct spi_nor_erase_map *map = &nor->erase_map;
> +	u8 i, erase_mask;
> +
>  	/* Set legacy flash parameters as default. */
>  	memset(params, 0, sizeof(*params));
> 
> @@ -2519,6 +2933,28 @@ static int spi_nor_init_params(struct spi_nor *nor,
>  	spi_nor_set_pp_settings(&params->page_programs[SNOR_CMD_PP],
>  				SPINOR_OP_PP, SNOR_PROTO_1_1_1);
> 
> +	/*
> +	 * Sector Erase settings. Sort Erase Types in ascending order, with the
> +	 * smallest erase size starting at BIT(0).
> +	 */
> +	erase_mask = 0;
> +	i = 0;
> +	if (info->flags & SECT_4K_PMC) {
> +		erase_mask |= BIT(i);
> +		spi_nor_set_erase_type(&map->erase_type[i], 4096u,
> +				       SPINOR_OP_BE_4K_PMC);
> +		i++;
> +	} else if (info->flags & SECT_4K) {
> +		erase_mask |= BIT(i);
> +		spi_nor_set_erase_type(&map->erase_type[i], 4096u,
> +				       SPINOR_OP_BE_4K);
> +		i++;
> +	}
> +	erase_mask |= BIT(i);
> +	spi_nor_set_erase_type(&map->erase_type[i], info->sector_size,
> +			       SPINOR_OP_SE);
> +	spi_nor_init_uniform_erase_map(map, erase_mask, params->size);
> +
>  	/* Select the procedure to set the Quad Enable bit. */
>  	if (params->hwcaps.mask & (SNOR_HWCAPS_READ_QUAD |
>  				   SNOR_HWCAPS_PP_QUAD)) {
> @@ -2546,20 +2982,20 @@ static int spi_nor_init_params(struct spi_nor *nor,
>  			params->quad_enable = info->quad_enable;
>  	}
> 
> -	/* Override the parameters with data read from SFDP tables. */
> -	nor->addr_width = 0;
> -	nor->mtd.erasesize = 0;
>  	if ((info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)) &&
>  	    !(info->flags & SPI_NOR_SKIP_SFDP)) {
>  		struct spi_nor_flash_parameter sfdp_params;
> +		struct spi_nor_erase_map prev_map;
> 
>  		memcpy(&sfdp_params, params, sizeof(sfdp_params));
> -		if (spi_nor_parse_sfdp(nor, &sfdp_params)) {
> -			nor->addr_width = 0;
> -			nor->mtd.erasesize = 0;
> -		} else {
> +		memcpy(&prev_map, &nor->erase_map, sizeof(prev_map));
> +
> +		if (spi_nor_parse_sfdp(nor, &sfdp_params))
> +			/* restore previous erase map */
> +			memcpy(&nor->erase_map, &prev_map,
> +			       sizeof(nor->erase_map));
> +		else
>  			memcpy(params, &sfdp_params, sizeof(*params));
> -		}
>  	}
> 
>  	return 0;
> @@ -2668,29 +3104,103 @@ static int spi_nor_select_pp(struct spi_nor *nor,
>  	return 0;
>  }
> 
> -static int spi_nor_select_erase(struct spi_nor *nor,
> -				const struct flash_info *info)
> +/*
> + * spi_nor_select_uniform_erase() - select optimum uniform erase type
> + * @map:		the erase map of the SPI NOR
> + * @wanted_size:	the erase type size to search for. Contains the value of
> + *			info->sector_size or of the "small sector" size in case
> + *			CONFIG_MTD_SPI_NOR_USE_4K_SECTORS is defined.
> + *
> + * Once the optimum uniform sector erase command is found, disable all
> +the
> + * other.
> + *
> + * Return: pointer to erase type on success, NULL otherwise.
> + */
> +static const struct spi_nor_erase_type *
> +spi_nor_select_uniform_erase(struct spi_nor_erase_map *map,
> +			     const u32 wanted_size)
>  {
> -	struct mtd_info *mtd = &nor->mtd;
> +	const struct spi_nor_erase_type *tested_erase, *erase = NULL;
> +	int i;
> +	u8 uniform_erase_type = map->uniform_erase_type;
> 
> -	/* Do nothing if already configured from SFDP. */
> -	if (mtd->erasesize)
> -		return 0;
> +	for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
> +		if (!(uniform_erase_type & BIT(i)))
> +			continue;
> +
> +		tested_erase = &map->erase_type[i];
> +
> +		/*
> +		 * If the current erase size is the one, stop here:
> +		 * we have found the right uniform Sector Erase command.
> +		 */
> +		if (tested_erase->size == wanted_size) {
> +			erase = tested_erase;
> +			break;
> +		}
> 
> +		/*
> +		 * Otherwise, the current erase size is still a valid canditate.
> +		 * Select the biggest valid candidate.
> +		 */
> +		if (!erase && tested_erase->size)
> +			erase = tested_erase;
> +			/* keep iterating to find the wanted_size */
> +	}
> +
> +	if (!erase)
> +		return NULL;
> +
> +	/* Disable all other Sector Erase commands. */
> +	map->uniform_erase_type &= ~SNOR_ERASE_TYPE_MASK;
> +	map->uniform_erase_type |= BIT(erase - map->erase_type);
> +	return erase;
> +}
> +
> +static int spi_nor_select_erase(struct spi_nor *nor, u32 wanted_size) {
> +	struct spi_nor_erase_map *map = &nor->erase_map;
> +	const struct spi_nor_erase_type *erase = NULL;
> +	struct mtd_info *mtd = &nor->mtd;
> +	int i;
> +
> +	/*
> +	 * The previous implementation handling Sector Erase commands
> assumed
> +	 * that the SPI flash memory has an uniform layout then used only one
> +	 * of the supported erase sizes for all Sector Erase commands.
> +	 * So to be backward compatible, the new implementation also tries to
> +	 * manage the SPI flash memory as uniform with a single erase sector
> +	 * size, when possible.
> +	 */
>  #ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
>  	/* prefer "small sector" erase if possible */
> -	if (info->flags & SECT_4K) {
> -		nor->erase_opcode = SPINOR_OP_BE_4K;
> -		mtd->erasesize = 4096;
> -	} else if (info->flags & SECT_4K_PMC) {
> -		nor->erase_opcode = SPINOR_OP_BE_4K_PMC;
> -		mtd->erasesize = 4096;
> -	} else
> +	wanted_size = 4096u;
>  #endif
> -	{
> -		nor->erase_opcode = SPINOR_OP_SE;
> -		mtd->erasesize = info->sector_size;
> +
> +	if (spi_nor_has_uniform_erase(nor)) {
> +		erase = spi_nor_select_uniform_erase(map, wanted_size);
> +		if (!erase)
> +			return -EINVAL;
> +		nor->erase_opcode = erase->opcode;
> +		mtd->erasesize = erase->size;
> +		return 0;
>  	}
> +
> +	/*
> +	 * For non-uniform SPI flash memory, set mtd->erasesize to the
> +	 * maximum erase sector size. No need to set nor->erase_opcode.
> +	 */
> +	for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
> +		if (map->erase_type[i].size) {
> +			erase = &map->erase_type[i];
> +			break;
> +		}
> +	}
> +
> +	if (!erase)
> +		return -EINVAL;
> +
> +	mtd->erasesize = erase->size;
>  	return 0;
>  }
> 
> @@ -2737,7 +3247,7 @@ static int spi_nor_setup(struct spi_nor *nor, const
> struct flash_info *info,
>  	}
> 
>  	/* Select the Sector Erase command. */
> -	err = spi_nor_select_erase(nor, info);
> +	err = spi_nor_select_erase(nor, info->sector_size);
>  	if (err) {
>  		dev_err(nor->dev,
>  			"can't select erase settings supported by both the SPI
> controller and memory.\n"); diff --git a/include/linux/mtd/spi-nor.h
> b/include/linux/mtd/spi-nor.h index 09a10fd..a873a0b 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -240,6 +240,94 @@ enum spi_nor_option_flags {  };
> 
>  /**
> + * struct spi_nor_erase_type - Structure to describe a SPI NOR erase type
> + * @size:		the size of the sector/block erased by the erase type.
> + *			JEDEC JESD216B imposes erase sizes to be a power of 2.
> + * @size_shift:		@size is a power of 2, the shift is stored in
> + *			@size_shift.
> + * @size_mask:		the size mask based on @size_shift.
> + * @opcode:		the SPI command op code to erase the sector/block.
> + * @idx:		Erase Type index as sorted in the Basic Flash Parameter
> + *			Table. It will be used to synchronize the supported
> + *			Erase Types with the ones identified in the SFDP
> + *			optional tables.
> + */
> +struct spi_nor_erase_type {
> +	u32	size;
> +	u32	size_shift;
> +	u32	size_mask;
> +	u8	opcode;
> +	u8	idx;
> +};
> +
> +/**
> + * struct spi_nor_erase_command - Used for non-uniform erases
> + * The structure is used to describe a list of erase commands to be
> +executed
> + * once we validate that the erase can be performed. The elements in
> +the list
> + * are run-length encoded.
> + * @list:		for inclusion into the list of erase commands.
> + * @count:		how many times the same erase command should be
> + *			consecutively used.
> + * @size:		the size of the sector/block erased by the command.
> + * @opcode:		the SPI command op code to erase the sector/block.
> + */
> +struct spi_nor_erase_command {
> +	struct list_head	list;
> +	u32			count;
> +	u32			size;
> +	u8			opcode;
> +};
> +
> +/**
> + * struct spi_nor_erase_region - Structure to describe a SPI NOR erase region
> + * @offset:		the offset in the data array of erase region start.
> + *			LSB bits are used as a bitmask encoding flags to
> + *			determine if this region is overlaid, if this region is
> + *			the last in the SPI NOR flash memory and to indicate
> + *			all the supported erase commands inside this region.
> + *			The erase types are sorted in ascending order with the
> + *			smallest Erase Type size being at BIT(0).
> + * @size:		the size of the region in bytes.
> + */
> +struct spi_nor_erase_region {
> +	u64		offset;
> +	u64		size;
> +};
> +
> +#define SNOR_ERASE_TYPE_MAX	4
> +#define SNOR_ERASE_TYPE_MASK
> 	GENMASK_ULL(SNOR_ERASE_TYPE_MAX - 1, 0)
> +
> +#define SNOR_LAST_REGION	BIT(4)
> +#define SNOR_OVERLAID_REGION	BIT(5)
> +
> +#define SNOR_ERASE_FLAGS_MAX	6
> +#define SNOR_ERASE_FLAGS_MASK
> 	GENMASK_ULL(SNOR_ERASE_FLAGS_MAX - 1, 0)
> +
> +/**
> + * struct spi_nor_erase_map - Structure to describe the SPI NOR erase map
> + * @regions:		array of erase regions. The regions are consecutive in
> + *			address space. Walking through the regions is done
> + *			incrementally.
> + * @uniform_region:	a pre-allocated erase region for SPI NOR with a uniform
> + *			sector size (legacy implementation).
> + * @erase_type:		an array of erase types shared by all the regions.
> + *			The erase types are sorted in ascending order, with the
> + *			smallest Erase Type size being the first member in the
> + *			erase_type array.
> + * @uniform_erase_type:	bitmask encoding erase types that can erase
> the
> + *			entire memory. This member is completed at init by
> + *			uniform and non-uniform SPI NOR flash memories if
> they
> + *			support at least one erase type that can erase the
> + *			entire memory.
> + */
> +struct spi_nor_erase_map {
> +	struct spi_nor_erase_region	*regions;
> +	struct spi_nor_erase_region	uniform_region;
> +	struct spi_nor_erase_type	erase_type[SNOR_ERASE_TYPE_MAX];
> +	u8				uniform_erase_type;
> +};
> +
> +/**
>   * struct flash_info - Forward declaration of a structure used internally by
>   *		       spi_nor_scan()
>   */
> @@ -263,6 +351,7 @@ struct flash_info;
>   * @write_proto:	the SPI protocol for write operations
>   * @reg_proto		the SPI protocol for read_reg/write_reg/erase
> operations
>   * @cmd_buf:		used by the write_reg
> + * @erase_map:		the erase map of the SPI NOR
>   * @prepare:		[OPTIONAL] do some preparations for the
>   *			read/write/erase/lock/unlock operations
>   * @unprepare:		[OPTIONAL] do some post work after the
> @@ -298,6 +387,7 @@ struct spi_nor {
>  	bool			sst_write_second;
>  	u32			flags;
>  	u8			cmd_buf[SPI_NOR_MAX_CMD_SIZE];
> +	struct spi_nor_erase_map	erase_map;
> 
>  	int (*prepare)(struct spi_nor *nor, enum spi_nor_ops ops);
>  	void (*unprepare)(struct spi_nor *nor, enum spi_nor_ops ops); @@ -
> 318,6 +408,23 @@ struct spi_nor {
>  	void *priv;
>  };
> 
> +static u64 __maybe_unused
> +spi_nor_region_is_last(const struct spi_nor_erase_region *region) {
> +	return region->offset & SNOR_LAST_REGION; }
> +
> +static u64 __maybe_unused
> +spi_nor_region_end(const struct spi_nor_erase_region *region) {
> +	return (region->offset & ~SNOR_ERASE_FLAGS_MASK) + region->size; }
> +
> +static bool __maybe_unused spi_nor_has_uniform_erase(const struct
> +spi_nor *nor) {
> +	return !!nor->erase_map.uniform_erase_type;
> +}
> +
>  static inline void spi_nor_set_flash_node(struct spi_nor *nor,
>  					  struct device_node *np)
>  {
> --
> 2.9.4
> 
> 
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