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openwrt/target/linux/generic/pending-6.1/402-mtd-spi-nor-write-suppo...

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From acacdac272927ae1d96e0bca51eb82899671eaea Mon Sep 17 00:00:00 2001
From: John Thomson <git@johnthomson.fastmail.com.au>
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 <git@johnthomson.fastmail.com.au>
Signed-off-by: Thibaut VARÈNE <hacks+kernel@slashdirt.org>
---
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 <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
---
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
@@ -169,6 +169,15 @@ 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)
{
@@ -314,6 +323,7 @@ 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
@@ -1049,6 +1049,8 @@ 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;
}
@@ -2157,6 +2159,7 @@ 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;
@@ -2189,8 +2192,9 @@ 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];
}
}
@@ -2198,6 +2202,9 @@ 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
@@ -245,6 +245,8 @@ 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
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