From acacdac272927ae1d96e0bca51eb82899671eaea Mon Sep 17 00:00:00 2001 From: John Thomson Date: Fri, 25 Dec 2020 18:50:08 +1000 Subject: [PATCH] mtd: spi-nor: write support for minor aligned partitions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Do not prevent writing to mtd partitions where a partition boundary sits on a minor erasesize boundary. This addresses a FIXME that has been present since the start of the linux git history: /* Doesn't start on a boundary of major erase size */ /* FIXME: Let it be writable if it is on a boundary of * _minor_ erase size though */ Allow a uniform erase region spi-nor device to be configured to use the non-uniform erase regions code path for an erase with: CONFIG_MTD_SPI_NOR_USE_VARIABLE_ERASE=y On supporting hardware (SECT_4K: majority of current SPI-NOR device) provide the facility for an erase to use the least number of SPI-NOR operations, as well as access to 4K erase without requiring CONFIG_MTD_SPI_NOR_USE_4K_SECTORS Introduce erasesize_minor to the mtd struct, the smallest erasesize supported by the device On existing devices, this is useful where write support is wanted for data on a 4K partition, such as some u-boot-env partitions, or RouterBoot soft_config, while still netting the performance benefits of using 64K sectors Performance: time mtd erase firmware OpenWrt 5.10 ramips MT7621 w25q128jv 0xfc0000 partition length Without this patch MTD_SPI_NOR_USE_4K_SECTORS=y |n real 2m 11.66s |0m 50.86s user 0m 0.00s |0m 0.00s sys 1m 56.20s |0m 50.80s With this patch MTD_SPI_NOR_USE_VARIABLE_ERASE=n|y |4K_SECTORS=y real 0m 51.68s |0m 50.85s |2m 12.89s user 0m 0.00s |0m 0.00s |0m 0.01s sys 0m 46.94s |0m 50.38s |2m 12.46s Signed-off-by: John Thomson Signed-off-by: Thibaut VARÈNE --- checkpatch does not like the printk(KERN_WARNING these should be changed separately beforehand? Changes v1 -> v2: Added mtdcore sysfs for erasesize_minor Removed finding minor erasesize for variable erase regions device, as untested and no responses regarding it. Moved IF_ENABLED for SPINOR variable erase to guard setting erasesize_minor in spi-nor/core.c Removed setting erasesize to minor where partition boundaries require minor erase to be writable Simplified minor boundary check by relying on minor being a factor of major Changes RFC -> v1: Fix uninitialized variable smatch warning Reported-by: kernel test robot Reported-by: Dan Carpenter --- drivers/mtd/mtdcore.c | 10 ++++++++++ drivers/mtd/mtdpart.c | 35 +++++++++++++++++++++++++---------- drivers/mtd/spi-nor/Kconfig | 10 ++++++++++ drivers/mtd/spi-nor/core.c | 11 +++++++++-- include/linux/mtd/mtd.h | 2 ++ 5 files changed, 56 insertions(+), 12 deletions(-) --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -168,6 +168,15 @@ static ssize_t mtd_erasesize_show(struct } MTD_DEVICE_ATTR_RO(erasesize); +static ssize_t mtd_erasesize_minor_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct mtd_info *mtd = dev_get_drvdata(dev); + + return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->erasesize_minor); +} +MTD_DEVICE_ATTR_RO(erasesize_minor); + static ssize_t mtd_writesize_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -313,6 +322,7 @@ static struct attribute *mtd_attrs[] = { &dev_attr_flags.attr, &dev_attr_size.attr, &dev_attr_erasesize.attr, + &dev_attr_erasesize_minor.attr, &dev_attr_writesize.attr, &dev_attr_subpagesize.attr, &dev_attr_oobsize.attr, --- a/drivers/mtd/mtdpart.c +++ b/drivers/mtd/mtdpart.c @@ -41,6 +41,7 @@ static struct mtd_info *allocate_partiti struct mtd_info *master = mtd_get_master(parent); int wr_alignment = (parent->flags & MTD_NO_ERASE) ? master->writesize : master->erasesize; + int wr_alignment_minor = 0; u64 parent_size = mtd_is_partition(parent) ? parent->part.size : parent->size; struct mtd_info *child; @@ -165,6 +166,7 @@ static struct mtd_info *allocate_partiti } else { /* Single erase size */ child->erasesize = master->erasesize; + child->erasesize_minor = master->erasesize_minor; } /* @@ -172,26 +174,39 @@ static struct mtd_info *allocate_partiti * exposes several regions with different erasesize. Adjust * wr_alignment accordingly. */ - if (!(child->flags & MTD_NO_ERASE)) + if (!(child->flags & MTD_NO_ERASE)) { wr_alignment = child->erasesize; + wr_alignment_minor = child->erasesize_minor; + } tmp = mtd_get_master_ofs(child, 0); remainder = do_div(tmp, wr_alignment); if ((child->flags & MTD_WRITEABLE) && remainder) { - /* Doesn't start on a boundary of major erase size */ - /* FIXME: Let it be writable if it is on a boundary of - * _minor_ erase size though */ - child->flags &= ~MTD_WRITEABLE; - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n", - part->name); + if (wr_alignment_minor) { + /* rely on minor being a factor of major erasesize */ + tmp = remainder; + remainder = do_div(tmp, wr_alignment_minor); + } + if (remainder) { + child->flags &= ~MTD_WRITEABLE; + printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n", + part->name); + } } tmp = mtd_get_master_ofs(child, 0) + child->part.size; remainder = do_div(tmp, wr_alignment); if ((child->flags & MTD_WRITEABLE) && remainder) { - child->flags &= ~MTD_WRITEABLE; - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n", - part->name); + if (wr_alignment_minor) { + tmp = remainder; + remainder = do_div(tmp, wr_alignment_minor); + } + + if (remainder) { + child->flags &= ~MTD_WRITEABLE; + printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n", + part->name); + } } child->size = child->part.size; --- a/drivers/mtd/spi-nor/Kconfig +++ b/drivers/mtd/spi-nor/Kconfig @@ -10,6 +10,16 @@ menuconfig MTD_SPI_NOR if MTD_SPI_NOR +config MTD_SPI_NOR_USE_VARIABLE_ERASE + bool "Disable uniform_erase to allow use of all hardware supported erasesizes" + depends on !MTD_SPI_NOR_USE_4K_SECTORS + default n + help + Allow mixed use of all hardware supported erasesizes, + by forcing spi_nor to use the multiple eraseregions code path. + For example: A 68K erase will use one 64K erase, and one 4K erase + on supporting hardware. + config MTD_SPI_NOR_USE_4K_SECTORS bool "Use small 4096 B erase sectors" default y --- a/drivers/mtd/spi-nor/core.c +++ b/drivers/mtd/spi-nor/core.c @@ -1271,6 +1271,8 @@ static u8 spi_nor_convert_3to4_erase(u8 static bool spi_nor_has_uniform_erase(const struct spi_nor *nor) { + if (IS_ENABLED(CONFIG_MTD_SPI_NOR_USE_VARIABLE_ERASE)) + return false; return !!nor->params->erase_map.uniform_erase_type; } @@ -2388,6 +2390,7 @@ static int spi_nor_select_erase(struct s { struct spi_nor_erase_map *map = &nor->params->erase_map; const struct spi_nor_erase_type *erase = NULL; + const struct spi_nor_erase_type *erase_minor = NULL; struct mtd_info *mtd = &nor->mtd; u32 wanted_size = nor->info->sector_size; int i; @@ -2420,8 +2423,9 @@ static int spi_nor_select_erase(struct s */ for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) { if (map->erase_type[i].size) { - erase = &map->erase_type[i]; - break; + if (!erase) + erase = &map->erase_type[i]; + erase_minor = &map->erase_type[i]; } } @@ -2429,6 +2433,9 @@ static int spi_nor_select_erase(struct s return -EINVAL; mtd->erasesize = erase->size; + if (IS_ENABLED(CONFIG_MTD_SPI_NOR_USE_VARIABLE_ERASE) && + erase_minor && erase_minor->size < erase->size) + mtd->erasesize_minor = erase_minor->size; return 0; } --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -243,6 +243,8 @@ struct mtd_info { * information below if they desire */ uint32_t erasesize; + /* "Minor" (smallest) erase size supported by the whole device */ + uint32_t erasesize_minor; /* Minimal writable flash unit size. In case of NOR flash it is 1 (even * though individual bits can be cleared), in case of NAND flash it is * one NAND page (or half, or one-fourths of it), in case of ECC-ed NOR