| Message ID | e5b709e15739dc0563e9497a2dbbe63050381db0.1689802933.git.daniel@makrotopia.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | nvmem: add block device NVMEM provider | expand |
On 7/20/23 07:04, Daniel Golle wrote: > On embedded devices using an eMMC it is common that one or more partitions > on the eMMC are used to store MAC addresses and Wi-Fi calibration EEPROM > data. Allow referencing the partition in device tree for the kernel and > Wi-Fi drivers accessing it via the NVMEM layer. > > Signed-off-by: Daniel Golle <daniel@makrotopia.org> > --- > block/Kconfig | 8 ++ > block/Makefile | 1 + > block/blk-nvmem.c | 187 ++++++++++++++++++++++++++++++++++++++++ > block/blk.h | 13 +++ > block/genhd.c | 2 + > block/partitions/core.c | 2 + > 6 files changed, 213 insertions(+) > create mode 100644 block/blk-nvmem.c > > diff --git a/block/Kconfig b/block/Kconfig > index 86122e459fe04..185573877964d 100644 > --- a/block/Kconfig > +++ b/block/Kconfig > @@ -218,6 +218,14 @@ config BLK_MQ_VIRTIO > config BLK_PM > def_bool PM > > +config BLK_NVMEM > + bool "Block device NVMEM provider" > + depends on OF > + help > + Allow block devices (or partitions) to act as NVMEM prodivers, > + typically using if an eMMC is used to store MAC addresses or Wi-Fi Odd grammar... May be "typically used with eMMC to store ..." > + calibration data on embedded devices. > + > # do not use in new code > config BLOCK_HOLDER_DEPRECATED > bool > diff --git a/block/Makefile b/block/Makefile > index 46ada9dc8bbfe..03c0bfa8642df 100644 > --- a/block/Makefile > +++ b/block/Makefile > @@ -34,6 +34,7 @@ obj-$(CONFIG_BLK_DEV_ZONED) += blk-zoned.o > obj-$(CONFIG_BLK_WBT) += blk-wbt.o > obj-$(CONFIG_BLK_DEBUG_FS) += blk-mq-debugfs.o > obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o > +obj-$(CONFIG_BLK_NVMEM) += blk-nvmem.o > obj-$(CONFIG_BLK_SED_OPAL) += sed-opal.o > obj-$(CONFIG_BLK_PM) += blk-pm.o > obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += blk-crypto.o blk-crypto-profile.o \ > diff --git a/block/blk-nvmem.c b/block/blk-nvmem.c > new file mode 100644 > index 0000000000000..8238511049f56 > --- /dev/null > +++ b/block/blk-nvmem.c > @@ -0,0 +1,187 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * block device NVMEM provider > + * > + * Copyright (c) 2023 Daniel Golle <daniel@makrotopia.org> > + * > + * Useful on devices using a partition on an eMMC for MAC addresses or > + * Wi-Fi calibration EEPROM data. > + */ > + > +#include "blk.h" > +#include <linux/nvmem-provider.h> > +#include <linux/of.h> > +#include <linux/pagemap.h> > +#include <linux/property.h> > + > +/* List of all NVMEM devices */ > +static LIST_HEAD(nvmem_devices); > +static DEFINE_MUTEX(devices_mutex); > + > +struct blk_nvmem { > + struct nvmem_device *nvmem; > + struct block_device *bdev; > + struct list_head list; > +}; > + > +static int blk_nvmem_reg_read(void *priv, unsigned int from, > + void *val, size_t bytes) > +{ > + pgoff_t f_index = from >> PAGE_SHIFT; > + struct address_space *mapping; > + struct blk_nvmem *bnv = priv; Why not have bnv passed as argument directly ? > + size_t bytes_left = bytes; > + struct folio *folio; > + unsigned long offs, to_read; > + void *p; > + > + if (!bnv->bdev) > + return -ENODEV; > + > + offs = from & ((1 << PAGE_SHIFT) - 1); offs = from & PAGE_MASK; from being an int is really odd though. > + mapping = bnv->bdev->bd_inode->i_mapping; > + > + while (bytes_left) { > + folio = read_mapping_folio(mapping, f_index++, NULL); > + if (IS_ERR(folio)) > + return PTR_ERR(folio); > + > + to_read = min_t(unsigned long, bytes_left, PAGE_SIZE - offs); > + p = folio_address(folio) + offset_in_folio(folio, offs); > + memcpy(val, p, to_read); > + offs = 0; > + bytes_left -= to_read; > + val += to_read; > + folio_put(folio); > + } > + > + return bytes_left == 0 ? 0 : -EIO; How can bytes_left be 0 here given the above loop with no break ? > +} > + > +void blk_register_nvmem(struct block_device *bdev) > +{ > + struct fwnode_handle *fw_parts = NULL, *fw_part_c, *fw_part = NULL; > + struct nvmem_config config = {}; > + const char *partname, *uuid; > + struct device *dev, *p0dev; > + struct blk_nvmem *bnv; > + u32 reg; > + > + /* > + * skip devices which set GENHD_FL_NO_NVMEM > + * > + * This flag is used for mtdblock and ubiblock devices because > + * both, MTD and UBI already implement their own NVMEM provider. > + * To avoid registering multiple NVMEM providers for the same > + * device node, skip the block NVMEM provider. > + */ > + if (bdev->bd_disk->flags & GENHD_FL_NO_NVMEM) > + return; > + > + /* skip too large devices */ Why ? Is that defined in some standards somewhere ? > + if (bdev_nr_bytes(bdev) > INT_MAX) > + return; > + > + dev = &bdev->bd_device; > + if (!bdev_is_partition(bdev)) { > + fw_part = dev->fwnode; > + > + if (!fw_part && dev->parent) > + fw_part = dev->parent->fwnode; > + > + goto no_parts; > + } > + > + p0dev = &bdev->bd_disk->part0->bd_device; > + fw_parts = device_get_named_child_node(p0dev, "partitions"); > + if (!fw_parts) > + fw_parts = device_get_named_child_node(p0dev->parent, "partitions"); > + > + if (!fw_parts) > + return; > + > + fwnode_for_each_child_node(fw_parts, fw_part_c) { > + if (!fwnode_property_read_string(fw_part_c, "uuid", &uuid) && > + (!bdev->bd_meta_info || strncmp(uuid, > + bdev->bd_meta_info->uuid, > + PARTITION_META_INFO_UUIDLTH))) > + continue; > + > + if (!fwnode_property_read_string(fw_part_c, "partname", &partname) && > + (!bdev->bd_meta_info || strncmp(partname, > + bdev->bd_meta_info->volname, > + PARTITION_META_INFO_VOLNAMELTH))) > + continue; > + > + /* > + * partition addresses (reg) in device tree greater than > + * DISK_MAX_PARTS can be used to match uuid or partname only > + */ > + if (!fwnode_property_read_u32(fw_part_c, "reg", ®) && > + reg < DISK_MAX_PARTS && bdev->bd_partno != reg) > + continue; > + > + fw_part = fw_part_c; > + break; > + } > + > +no_parts: > + if (!fwnode_device_is_compatible(fw_part, "nvmem-cells")) > + return; > + > + bnv = kzalloc(sizeof(struct blk_nvmem), GFP_KERNEL); > + if (!bnv) > + return; > + > + config.id = NVMEM_DEVID_NONE; > + config.dev = &bdev->bd_device; > + config.name = dev_name(&bdev->bd_device); > + config.owner = THIS_MODULE; > + config.priv = bnv; > + config.reg_read = blk_nvmem_reg_read; > + config.size = bdev_nr_bytes(bdev); > + config.word_size = 1; > + config.stride = 1; > + config.read_only = true; > + config.root_only = true; > + config.ignore_wp = true; > + config.of_node = to_of_node(fw_part); > + > + bnv->bdev = bdev; > + bnv->nvmem = nvmem_register(&config); > + if (IS_ERR(bnv->nvmem)) { > + /* Just ignore if there is no NVMEM support in the kernel */ If there is not, why would this function even be called ? > + if (PTR_ERR(bnv->nvmem) != -EOPNOTSUPP) > + dev_err_probe(&bdev->bd_device, PTR_ERR(bnv->nvmem), > + "Failed to register NVMEM device\n"); > + > + kfree(bnv); > + return; > + } > + > + mutex_lock(&devices_mutex); > + list_add_tail(&bnv->list, &nvmem_devices); > + mutex_unlock(&devices_mutex); > +} > + > +void blk_unregister_nvmem(struct block_device *bdev) > +{ > + struct blk_nvmem *bnv_c, *bnv = NULL; > + > + mutex_lock(&devices_mutex); > + list_for_each_entry(bnv_c, &nvmem_devices, list) > + if (bnv_c->bdev == bdev) { > + bnv = bnv_c; > + break; > + } Curly brackets for list_for_each_entry() {} would be nice, even though they are not strictly necessary in this case. > + > + if (!bnv) { > + mutex_unlock(&devices_mutex); > + return; > + } > + > + list_del(&bnv->list); > + mutex_unlock(&devices_mutex); > + nvmem_unregister(bnv->nvmem); > + kfree(bnv); > +} > diff --git a/block/blk.h b/block/blk.h > index 686712e138352..7423d0d5494e9 100644 > --- a/block/blk.h > +++ b/block/blk.h > @@ -515,4 +515,17 @@ static inline int req_ref_read(struct request *req) > return atomic_read(&req->ref); > } > > +#ifdef CONFIG_BLK_NVMEM > +void blk_register_nvmem(struct block_device *bdev); > +void blk_unregister_nvmem(struct block_device *bdev); > +#else > +static inline void blk_register_nvmem(struct block_device *bdev) > +{ > +} These could go at the end of the static inline line. > + > +static inline void blk_unregister_nvmem(struct block_device *bdev) > +{ > +} > +#endif > + > #endif /* BLK_INTERNAL_H */ > diff --git a/block/genhd.c b/block/genhd.c > index 3d287b32d50df..b306e0f407bb2 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -527,6 +527,7 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk, > disk_update_readahead(disk); > disk_add_events(disk); > set_bit(GD_ADDED, &disk->state); > + blk_register_nvmem(disk->part0); > return 0; > > out_unregister_bdi: > @@ -569,6 +570,7 @@ static void blk_report_disk_dead(struct gendisk *disk) > if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead) > bdev->bd_holder_ops->mark_dead(bdev); > mutex_unlock(&bdev->bd_holder_lock); > + blk_unregister_nvmem(bdev); > > put_device(&bdev->bd_device); > rcu_read_lock(); > diff --git a/block/partitions/core.c b/block/partitions/core.c > index 13a7341299a91..68bd655f5e68e 100644 > --- a/block/partitions/core.c > +++ b/block/partitions/core.c > @@ -404,6 +404,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno, > /* suppress uevent if the disk suppresses it */ > if (!dev_get_uevent_suppress(ddev)) > kobject_uevent(&pdev->kobj, KOBJ_ADD); > + > + blk_register_nvmem(bdev); > return bdev; > > out_del:
On Thu, Jul 20, 2023 at 08:04:56AM +0900, Damien Le Moal wrote: > On 7/20/23 07:04, Daniel Golle wrote: > > On embedded devices using an eMMC it is common that one or more partitions > > on the eMMC are used to store MAC addresses and Wi-Fi calibration EEPROM > > data. Allow referencing the partition in device tree for the kernel and > > Wi-Fi drivers accessing it via the NVMEM layer. > > > > Signed-off-by: Daniel Golle <daniel@makrotopia.org> > > --- > > block/Kconfig | 8 ++ > > block/Makefile | 1 + > > block/blk-nvmem.c | 187 ++++++++++++++++++++++++++++++++++++++++ > > block/blk.h | 13 +++ > > block/genhd.c | 2 + > > block/partitions/core.c | 2 + > > 6 files changed, 213 insertions(+) > > create mode 100644 block/blk-nvmem.c > > > > diff --git a/block/Kconfig b/block/Kconfig > > index 86122e459fe04..185573877964d 100644 > > --- a/block/Kconfig > > +++ b/block/Kconfig > > @@ -218,6 +218,14 @@ config BLK_MQ_VIRTIO > > config BLK_PM > > def_bool PM > > > > +config BLK_NVMEM > > + bool "Block device NVMEM provider" > > + depends on OF > > + help > > + Allow block devices (or partitions) to act as NVMEM prodivers, > > + typically using if an eMMC is used to store MAC addresses or Wi-Fi > > Odd grammar... May be "typically used with eMMC to store ..." Thank you, I'll use your suggestion. > > > + calibration data on embedded devices. > > + > > # do not use in new code > > config BLOCK_HOLDER_DEPRECATED > > bool > > diff --git a/block/Makefile b/block/Makefile > > index 46ada9dc8bbfe..03c0bfa8642df 100644 > > --- a/block/Makefile > > +++ b/block/Makefile > > @@ -34,6 +34,7 @@ obj-$(CONFIG_BLK_DEV_ZONED) += blk-zoned.o > > obj-$(CONFIG_BLK_WBT) += blk-wbt.o > > obj-$(CONFIG_BLK_DEBUG_FS) += blk-mq-debugfs.o > > obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o > > +obj-$(CONFIG_BLK_NVMEM) += blk-nvmem.o > > obj-$(CONFIG_BLK_SED_OPAL) += sed-opal.o > > obj-$(CONFIG_BLK_PM) += blk-pm.o > > obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += blk-crypto.o blk-crypto-profile.o \ > > diff --git a/block/blk-nvmem.c b/block/blk-nvmem.c > > new file mode 100644 > > index 0000000000000..8238511049f56 > > --- /dev/null > > +++ b/block/blk-nvmem.c > > @@ -0,0 +1,187 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > +/* > > + * block device NVMEM provider > > + * > > + * Copyright (c) 2023 Daniel Golle <daniel@makrotopia.org> > > + * > > + * Useful on devices using a partition on an eMMC for MAC addresses or > > + * Wi-Fi calibration EEPROM data. > > + */ > > + > > +#include "blk.h" > > +#include <linux/nvmem-provider.h> > > +#include <linux/of.h> > > +#include <linux/pagemap.h> > > +#include <linux/property.h> > > + > > +/* List of all NVMEM devices */ > > +static LIST_HEAD(nvmem_devices); > > +static DEFINE_MUTEX(devices_mutex); > > + > > +struct blk_nvmem { > > + struct nvmem_device *nvmem; > > + struct block_device *bdev; > > + struct list_head list; > > +}; > > + > > +static int blk_nvmem_reg_read(void *priv, unsigned int from, > > + void *val, size_t bytes) > > +{ > > + pgoff_t f_index = from >> PAGE_SHIFT; > > + struct address_space *mapping; > > + struct blk_nvmem *bnv = priv; > > Why not have bnv passed as argument directly ? Because blk_nvmem_reg_read is used as reg_read function, ie. nvmem_reg_read_t {aka 'int (*)(void *, unsigned int, void *, long unsigned int)'} Hence 'void *' has to be implicitely type-casted into 'struct blk_nvmem *'. > > > + size_t bytes_left = bytes; > > + struct folio *folio; > > + unsigned long offs, to_read; > > + void *p; > > + > > + if (!bnv->bdev) > > + return -ENODEV; > > + > > + offs = from & ((1 << PAGE_SHIFT) - 1); > > offs = from & PAGE_MASK; Right, that makes it easier... > > from being an int is really odd though. Yep, but that's how NVMEM framework defines it. > > > + mapping = bnv->bdev->bd_inode->i_mapping; > > + > > + while (bytes_left) { > > + folio = read_mapping_folio(mapping, f_index++, NULL); > > + if (IS_ERR(folio)) > > + return PTR_ERR(folio); > > + > > + to_read = min_t(unsigned long, bytes_left, PAGE_SIZE - offs); > > + p = folio_address(folio) + offset_in_folio(folio, offs); > > + memcpy(val, p, to_read); > > + offs = 0; > > + bytes_left -= to_read; > > + val += to_read; > > + folio_put(folio); > > + } > > + > > + return bytes_left == 0 ? 0 : -EIO; > > How can bytes_left be 0 here given the above loop with no break ? Well, right... Can just be 'return 0;' at this point obviously. > > > +} > > + > > +void blk_register_nvmem(struct block_device *bdev) > > +{ > > + struct fwnode_handle *fw_parts = NULL, *fw_part_c, *fw_part = NULL; > > + struct nvmem_config config = {}; > > + const char *partname, *uuid; > > + struct device *dev, *p0dev; > > + struct blk_nvmem *bnv; > > + u32 reg; > > + > > + /* > > + * skip devices which set GENHD_FL_NO_NVMEM > > + * > > + * This flag is used for mtdblock and ubiblock devices because > > + * both, MTD and UBI already implement their own NVMEM provider. > > + * To avoid registering multiple NVMEM providers for the same > > + * device node, skip the block NVMEM provider. > > + */ > > + if (bdev->bd_disk->flags & GENHD_FL_NO_NVMEM) > > + return; > > + > > + /* skip too large devices */ > > Why ? Is that defined in some standards somewhere ? NVMEM framework uses 'int' to address byte offsets inside NVMEM devices. Hence devices larger than INT_MAX cannot be addressed, I will also state that in that comment. > > > + if (bdev_nr_bytes(bdev) > INT_MAX) > > + return; > > + > > + dev = &bdev->bd_device; > > + if (!bdev_is_partition(bdev)) { > > + fw_part = dev->fwnode; > > + > > + if (!fw_part && dev->parent) > > + fw_part = dev->parent->fwnode; > > + > > + goto no_parts; > > + } > > + > > + p0dev = &bdev->bd_disk->part0->bd_device; > > + fw_parts = device_get_named_child_node(p0dev, "partitions"); > > + if (!fw_parts) > > + fw_parts = device_get_named_child_node(p0dev->parent, "partitions"); > > + > > + if (!fw_parts) > > + return; > > + > > + fwnode_for_each_child_node(fw_parts, fw_part_c) { > > + if (!fwnode_property_read_string(fw_part_c, "uuid", &uuid) && > > + (!bdev->bd_meta_info || strncmp(uuid, > > + bdev->bd_meta_info->uuid, > > + PARTITION_META_INFO_UUIDLTH))) > > + continue; > > + > > + if (!fwnode_property_read_string(fw_part_c, "partname", &partname) && > > + (!bdev->bd_meta_info || strncmp(partname, > > + bdev->bd_meta_info->volname, > > + PARTITION_META_INFO_VOLNAMELTH))) > > + continue; > > + > > + /* > > + * partition addresses (reg) in device tree greater than > > + * DISK_MAX_PARTS can be used to match uuid or partname only > > + */ > > + if (!fwnode_property_read_u32(fw_part_c, "reg", ®) && > > + reg < DISK_MAX_PARTS && bdev->bd_partno != reg) > > + continue; > > + > > + fw_part = fw_part_c; > > + break; > > + } > > + > > +no_parts: > > + if (!fwnode_device_is_compatible(fw_part, "nvmem-cells")) > > + return; > > + > > + bnv = kzalloc(sizeof(struct blk_nvmem), GFP_KERNEL); > > + if (!bnv) > > + return; > > + > > + config.id = NVMEM_DEVID_NONE; > > + config.dev = &bdev->bd_device; > > + config.name = dev_name(&bdev->bd_device); > > + config.owner = THIS_MODULE; > > + config.priv = bnv; > > + config.reg_read = blk_nvmem_reg_read; > > + config.size = bdev_nr_bytes(bdev); > > + config.word_size = 1; > > + config.stride = 1; > > + config.read_only = true; > > + config.root_only = true; > > + config.ignore_wp = true; > > + config.of_node = to_of_node(fw_part); > > + > > + bnv->bdev = bdev; > > + bnv->nvmem = nvmem_register(&config); > > + if (IS_ERR(bnv->nvmem)) { > > + /* Just ignore if there is no NVMEM support in the kernel */ > > If there is not, why would this function even be called ? True. Kconfig depends should make sure blk-nvmem is only built if nvmem is supported at all. > > > + if (PTR_ERR(bnv->nvmem) != -EOPNOTSUPP) > > + dev_err_probe(&bdev->bd_device, PTR_ERR(bnv->nvmem), > > + "Failed to register NVMEM device\n"); > > + > > + kfree(bnv); > > + return; > > + } > > + > > + mutex_lock(&devices_mutex); > > + list_add_tail(&bnv->list, &nvmem_devices); > > + mutex_unlock(&devices_mutex); > > +} > > + > > +void blk_unregister_nvmem(struct block_device *bdev) > > +{ > > + struct blk_nvmem *bnv_c, *bnv = NULL; > > + > > + mutex_lock(&devices_mutex); > > + list_for_each_entry(bnv_c, &nvmem_devices, list) > > + if (bnv_c->bdev == bdev) { > > + bnv = bnv_c; > > + break; > > + } > > Curly brackets for list_for_each_entry() {} would be nice, even though they are > not strictly necessary in this case. Ack, will add them. > > > + > > + if (!bnv) { > > + mutex_unlock(&devices_mutex); > > + return; > > + } > > + > > + list_del(&bnv->list); > > + mutex_unlock(&devices_mutex); > > + nvmem_unregister(bnv->nvmem); > > + kfree(bnv); > > +} > > diff --git a/block/blk.h b/block/blk.h > > index 686712e138352..7423d0d5494e9 100644 > > --- a/block/blk.h > > +++ b/block/blk.h > > @@ -515,4 +515,17 @@ static inline int req_ref_read(struct request *req) > > return atomic_read(&req->ref); > > } > > > > +#ifdef CONFIG_BLK_NVMEM > > +void blk_register_nvmem(struct block_device *bdev); > > +void blk_unregister_nvmem(struct block_device *bdev); > > +#else > > +static inline void blk_register_nvmem(struct block_device *bdev) > > +{ > > +} > > These could go at the end of the static inline line. I tried keeping the existing style in that header file. See a couple of lines above: static inline void bio_integrity_free(struct bio *bio) { } > > > + > > +static inline void blk_unregister_nvmem(struct block_device *bdev) > > +{ > > +} > > +#endif > > + > > #endif /* BLK_INTERNAL_H */ > > diff --git a/block/genhd.c b/block/genhd.c > > index 3d287b32d50df..b306e0f407bb2 100644 > > --- a/block/genhd.c > > +++ b/block/genhd.c > > @@ -527,6 +527,7 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk, > > disk_update_readahead(disk); > > disk_add_events(disk); > > set_bit(GD_ADDED, &disk->state); > > + blk_register_nvmem(disk->part0); > > return 0; > > > > out_unregister_bdi: > > @@ -569,6 +570,7 @@ static void blk_report_disk_dead(struct gendisk *disk) > > if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead) > > bdev->bd_holder_ops->mark_dead(bdev); > > mutex_unlock(&bdev->bd_holder_lock); > > + blk_unregister_nvmem(bdev); > > > > put_device(&bdev->bd_device); > > rcu_read_lock(); > > diff --git a/block/partitions/core.c b/block/partitions/core.c > > index 13a7341299a91..68bd655f5e68e 100644 > > --- a/block/partitions/core.c > > +++ b/block/partitions/core.c > > @@ -404,6 +404,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno, > > /* suppress uevent if the disk suppresses it */ > > if (!dev_get_uevent_suppress(ddev)) > > kobject_uevent(&pdev->kobj, KOBJ_ADD); > > + > > + blk_register_nvmem(bdev); > > return bdev; > > > > out_del: > > -- > Damien Le Moal > Western Digital Research >
The layering here is exactly the wrong way around. This block device as nvmem provide has not business sitting in the block layer and being keyed ff the gendisk registration. Instead you should create a new nvmem backed that opens the block device as needed if it fits your OF description without any changes to the core block layer.
On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > The layering here is exactly the wrong way around. This block device > as nvmem provide has not business sitting in the block layer and being > keyed ff the gendisk registration. Instead you should create a new > nvmem backed that opens the block device as needed if it fits your > OF description without any changes to the core block layer. > Ok. I will use a class_interface instead.
On Thu, Jul 20, 2023 at 05:02:32PM +0100, Daniel Golle wrote: > On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > > The layering here is exactly the wrong way around. This block device > > as nvmem provide has not business sitting in the block layer and being > > keyed ff the gendisk registration. Instead you should create a new > > nvmem backed that opens the block device as needed if it fits your > > OF description without any changes to the core block layer. > > > > Ok. I will use a class_interface instead. I'm not sure a class_interface makes much sense here. Why does the block layer even need to know about you using a device a nvmem provider? As far as I can tell your provider should layer entirely above the block layer and not have to be integrated with it.
> +static int blk_nvmem_reg_read(void *priv, unsigned int from, > + void *val, size_t bytes) > +{ > + pgoff_t f_index = from >> PAGE_SHIFT; > + struct address_space *mapping; > + struct blk_nvmem *bnv = priv; > + size_t bytes_left = bytes; > + struct folio *folio; > + unsigned long offs, to_read; > + void *p; Btw, this function really should be using kern_read on a file using filp_open instead of poking into block device internals. That way you can even have a generic file provider that works on anything that can be read from.
On Thu, Jul 20, 2023 at 11:31:06PM -0700, Christoph Hellwig wrote: > On Thu, Jul 20, 2023 at 05:02:32PM +0100, Daniel Golle wrote: > > On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > > > The layering here is exactly the wrong way around. This block device > > > as nvmem provide has not business sitting in the block layer and being > > > keyed ff the gendisk registration. Instead you should create a new > > > nvmem backed that opens the block device as needed if it fits your > > > OF description without any changes to the core block layer. > > > > > > > Ok. I will use a class_interface instead. > > I'm not sure a class_interface makes much sense here. Why does the > block layer even need to know about you using a device a nvmem provider? It doesn't. But it has to notify the nvmem providing driver about the addition of new block devices. This is what I'm using class_interface for, simply to hook into .add_dev of the block_class. > As far as I can tell your provider should layer entirely above the > block layer and not have to be integrated with it. My approach using class_interface doesn't require any changes to be made to existing block code. However, it does use block_class. If you see any other good option to implement matching off and usage of block devices by in-kernel users, please let me know.
On Fri, Jul 21, 2023 at 11:40:51AM +0100, Daniel Golle wrote: > On Thu, Jul 20, 2023 at 11:31:06PM -0700, Christoph Hellwig wrote: > > On Thu, Jul 20, 2023 at 05:02:32PM +0100, Daniel Golle wrote: > > > On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > > > > The layering here is exactly the wrong way around. This block device > > > > as nvmem provide has not business sitting in the block layer and being > > > > keyed ff the gendisk registration. Instead you should create a new > > > > nvmem backed that opens the block device as needed if it fits your > > > > OF description without any changes to the core block layer. > > > > > > > > > > Ok. I will use a class_interface instead. > > > > I'm not sure a class_interface makes much sense here. Why does the > > block layer even need to know about you using a device a nvmem provider? > > It doesn't. But it has to notify the nvmem providing driver about the > addition of new block devices. This is what I'm using class_interface > for, simply to hook into .add_dev of the block_class. Why is this single type of block device special to require this, yet all others do not? Encoding this into the block layer feels like a huge layering violation to me, why not do it how all other block drivers do it instead? > > As far as I can tell your provider should layer entirely above the > > block layer and not have to be integrated with it. > > My approach using class_interface doesn't require any changes to be > made to existing block code. However, it does use block_class. If > you see any other good option to implement matching off and usage of > block devices by in-kernel users, please let me know. Do not use block_class, again, that should only be for the block core to touch. Individual block drivers should never be poking around in it. thanks, greg k-h
On Fri, Jul 21, 2023 at 01:11:40PM +0200, Greg Kroah-Hartman wrote: > On Fri, Jul 21, 2023 at 11:40:51AM +0100, Daniel Golle wrote: > > On Thu, Jul 20, 2023 at 11:31:06PM -0700, Christoph Hellwig wrote: > > > On Thu, Jul 20, 2023 at 05:02:32PM +0100, Daniel Golle wrote: > > > > On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > > > > > The layering here is exactly the wrong way around. This block device > > > > > as nvmem provide has not business sitting in the block layer and being > > > > > keyed ff the gendisk registration. Instead you should create a new > > > > > nvmem backed that opens the block device as needed if it fits your > > > > > OF description without any changes to the core block layer. > > > > > > > > > > > > > Ok. I will use a class_interface instead. > > > > > > I'm not sure a class_interface makes much sense here. Why does the > > > block layer even need to know about you using a device a nvmem provider? > > > > It doesn't. But it has to notify the nvmem providing driver about the > > addition of new block devices. This is what I'm using class_interface > > for, simply to hook into .add_dev of the block_class. > > Why is this single type of block device special to require this, yet all > others do not? Encoding this into the block layer feels like a huge > layering violation to me, why not do it how all other block drivers do > it instead? I was thinkng of this as a generic solution in no way tied to one specific type of block device. *Any* internal block device which can be used to boot from should also be usable as NVMEM provider imho. Just like all MTD devices also act as NVMEM providers (just in case of block devices I'd make that opt-in via device tree). > > > > As far as I can tell your provider should layer entirely above the > > > block layer and not have to be integrated with it. > > > > My approach using class_interface doesn't require any changes to be > > made to existing block code. However, it does use block_class. If > > you see any other good option to implement matching off and usage of > > block devices by in-kernel users, please let me know. > > Do not use block_class, again, that should only be for the block core to > touch. Individual block drivers should never be poking around in it. Do I have any other options to coldplug and be notified about newly added block devices, so the block-device-consuming driver can know about them? This is not a rhetoric question, I've been looking for other ways and haven't found anything better than class_find_device or class_interface. Using those also prevents blk-nvmem to be built as a module, so I'd really like to find alternatives. E.g. for MTD we got struct mtd_notifier and register_mtd_user().
On Fri, Jul 21, 2023 at 12:30:10PM +0100, Daniel Golle wrote: > On Fri, Jul 21, 2023 at 01:11:40PM +0200, Greg Kroah-Hartman wrote: > > On Fri, Jul 21, 2023 at 11:40:51AM +0100, Daniel Golle wrote: > > > On Thu, Jul 20, 2023 at 11:31:06PM -0700, Christoph Hellwig wrote: > > > > On Thu, Jul 20, 2023 at 05:02:32PM +0100, Daniel Golle wrote: > > > > > On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > > > > > > The layering here is exactly the wrong way around. This block device > > > > > > as nvmem provide has not business sitting in the block layer and being > > > > > > keyed ff the gendisk registration. Instead you should create a new > > > > > > nvmem backed that opens the block device as needed if it fits your > > > > > > OF description without any changes to the core block layer. > > > > > > > > > > > > > > > > Ok. I will use a class_interface instead. > > > > > > > > I'm not sure a class_interface makes much sense here. Why does the > > > > block layer even need to know about you using a device a nvmem provider? > > > > > > It doesn't. But it has to notify the nvmem providing driver about the > > > addition of new block devices. This is what I'm using class_interface > > > for, simply to hook into .add_dev of the block_class. > > > > Why is this single type of block device special to require this, yet all > > others do not? Encoding this into the block layer feels like a huge > > layering violation to me, why not do it how all other block drivers do > > it instead? > > I was thinkng of this as a generic solution in no way tied to one specific > type of block device. *Any* internal block device which can be used to > boot from should also be usable as NVMEM provider imho. Define "internal" :) And that's all up to the boot process in userspace, the kernel doesn't care about this. > > > > As far as I can tell your provider should layer entirely above the > > > > block layer and not have to be integrated with it. > > > > > > My approach using class_interface doesn't require any changes to be > > > made to existing block code. However, it does use block_class. If > > > you see any other good option to implement matching off and usage of > > > block devices by in-kernel users, please let me know. > > > > Do not use block_class, again, that should only be for the block core to > > touch. Individual block drivers should never be poking around in it. > > Do I have any other options to coldplug and be notified about newly > added block devices, so the block-device-consuming driver can know > about them? What other options do you need? > This is not a rhetoric question, I've been looking for other ways > and haven't found anything better than class_find_device or > class_interface. Never use that, sorry, that's not for a driver to touch. > Using those also prevents blk-nvmem to be built as > a module, so I'd really like to find alternatives. > E.g. for MTD we got struct mtd_notifier and register_mtd_user(). Your storage/hardware driver should be the thing that "finds block devices" and registers them with the block class core, right? After that, what matters? confused, greg k-h
On Fri, Jul 21, 2023 at 01:39:18PM +0200, Greg Kroah-Hartman wrote: > On Fri, Jul 21, 2023 at 12:30:10PM +0100, Daniel Golle wrote: > > On Fri, Jul 21, 2023 at 01:11:40PM +0200, Greg Kroah-Hartman wrote: > > > On Fri, Jul 21, 2023 at 11:40:51AM +0100, Daniel Golle wrote: > > > > On Thu, Jul 20, 2023 at 11:31:06PM -0700, Christoph Hellwig wrote: > > > > > On Thu, Jul 20, 2023 at 05:02:32PM +0100, Daniel Golle wrote: > > > > > > On Thu, Jul 20, 2023 at 12:04:43AM -0700, Christoph Hellwig wrote: > > > > > > > The layering here is exactly the wrong way around. This block device > > > > > > > as nvmem provide has not business sitting in the block layer and being > > > > > > > keyed ff the gendisk registration. Instead you should create a new > > > > > > > nvmem backed that opens the block device as needed if it fits your > > > > > > > OF description without any changes to the core block layer. > > > > > > > > > > > > > > > > > > > Ok. I will use a class_interface instead. > > > > > > > > > > I'm not sure a class_interface makes much sense here. Why does the > > > > > block layer even need to know about you using a device a nvmem provider? > > > > > > > > It doesn't. But it has to notify the nvmem providing driver about the > > > > addition of new block devices. This is what I'm using class_interface > > > > for, simply to hook into .add_dev of the block_class. > > > > > > Why is this single type of block device special to require this, yet all > > > others do not? Encoding this into the block layer feels like a huge > > > layering violation to me, why not do it how all other block drivers do > > > it instead? > > > > I was thinkng of this as a generic solution in no way tied to one specific > > type of block device. *Any* internal block device which can be used to > > boot from should also be usable as NVMEM provider imho. > > Define "internal" :) Exactly, it could be anything, MMC, SATA, even USB. As long as there is a device tree node associated with the device, it could be referenced as an NVMEM provider. And that's what this series tries to implement. > > And that's all up to the boot process in userspace, the kernel doesn't > care about this. So lets look at any random embedded Linux router or Wi-Fi AP: Typically we got some kind of NAND or NOR flash memory with a hard-coded partitioning dedicating different areas in the flash to be used for the bootloader, bootloader environment, factory data (such as MAC addresses and Wi-Fi EEPROMs), a linux kernel, a root filesystem and some way to store user data. And things are not that different when using an eMMC instead of NOR flash, from the perspective of the OS the main difference is just that the eMMC is larger and represented as a block device and typically MBR or GPT partitioning is used. > > > > > > As far as I can tell your provider should layer entirely above the > > > > > block layer and not have to be integrated with it. > > > > > > > > My approach using class_interface doesn't require any changes to be > > > > made to existing block code. However, it does use block_class. If > > > > you see any other good option to implement matching off and usage of > > > > block devices by in-kernel users, please let me know. > > > > > > Do not use block_class, again, that should only be for the block core to > > > touch. Individual block drivers should never be poking around in it. > > > > Do I have any other options to coldplug and be notified about newly > > added block devices, so the block-device-consuming driver can know > > about them? > > What other options do you need? Either calls for adding/removing the NVMEM devices need to be added to block/genhd.c and block/partitions/core.c, and if that's not acceptable (see below), then we'd need something like register_mtd_user() would be for MTD: A way for a driver to cold-plug existing block devices and be notified about newly added ones. > > > This is not a rhetoric question, I've been looking for other ways > > and haven't found anything better than class_find_device or > > class_interface. > > Never use that, sorry, that's not for a driver to touch. > > > Using those also prevents blk-nvmem to be built as > > a module, so I'd really like to find alternatives. > > E.g. for MTD we got struct mtd_notifier and register_mtd_user(). > > Your storage/hardware driver should be the thing that "finds block > devices" and registers them with the block class core, right? After > that, what matters? Well, I'd say: Make the device available as NVMEM provider, as it could be needed for e.g. the Ethernet driver to know the MAC address to be used. This is how it is done for MTD devices here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mtd/mtdcore.c#n723 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mtd/mtdcore.c#n804 ... and then used for example here: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/arch/arm64/boot/dts/marvell/armada-3720-gl-mv1000.dts#n227 The idea to use a class_interface at all is a result of the criticism by Christoph Hellwig that the series requires changes to be made to the block subsystem, ie. calls to register and unregister the NVMEM provider. Yet another way would obviously be to let the block-device-providing driver (eg. drivers/mmc/core/block.c) register the NVMEM provider, but that would then have to be re-implemented for every relevant block driver which also seems wrong.
On Thu, Jul 20, 2023 at 11:35:55PM -0700, Christoph Hellwig wrote: > > +static int blk_nvmem_reg_read(void *priv, unsigned int from, > > + void *val, size_t bytes) > > +{ > > + pgoff_t f_index = from >> PAGE_SHIFT; > > + struct address_space *mapping; > > + struct blk_nvmem *bnv = priv; > > + size_t bytes_left = bytes; > > + struct folio *folio; > > + unsigned long offs, to_read; > > + void *p; > > Btw, this function really should be using kern_read on a file > using filp_open instead of poking into block device internals. Unfortunately filp_open requires a device inode on a filesystem to be able to open a block device. What if the root filesystem has not yet been mounted, or even requires NVMEM (let's say for the Ethernet MAC address to be known for a nfsroot, nbd or iSCSI to work) to be available first? Can you imagine we could implement something like filp_open_bdev which takes a (struct block_device *) as parameter instead of (const char *)? That would allow the driver to open and read from the block device before any filesystems (incl. /dev) become ready. > That way you can even have a generic file provider that works > on anything that can be read from. > While this could also be useful, it doesn't fulfil the requirement of making NVMEM available as early as possible for other drivers to use, e.g. for the Ethernet MAC address. And it would also heavily deviate from how things work with other types of flash storage typically used in embedded Linux devices such as SPI NOR or NAND flash which is represented as MTD device. Sidenote: block2mtd is also not an option because one cannot reference block2mtd devices in device tree, hence they cannot serve as NVMEM providers.
diff --git a/block/Kconfig b/block/Kconfig index 86122e459fe04..185573877964d 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -218,6 +218,14 @@ config BLK_MQ_VIRTIO config BLK_PM def_bool PM +config BLK_NVMEM + bool "Block device NVMEM provider" + depends on OF + help + Allow block devices (or partitions) to act as NVMEM prodivers, + typically using if an eMMC is used to store MAC addresses or Wi-Fi + calibration data on embedded devices. + # do not use in new code config BLOCK_HOLDER_DEPRECATED bool diff --git a/block/Makefile b/block/Makefile index 46ada9dc8bbfe..03c0bfa8642df 100644 --- a/block/Makefile +++ b/block/Makefile @@ -34,6 +34,7 @@ obj-$(CONFIG_BLK_DEV_ZONED) += blk-zoned.o obj-$(CONFIG_BLK_WBT) += blk-wbt.o obj-$(CONFIG_BLK_DEBUG_FS) += blk-mq-debugfs.o obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o +obj-$(CONFIG_BLK_NVMEM) += blk-nvmem.o obj-$(CONFIG_BLK_SED_OPAL) += sed-opal.o obj-$(CONFIG_BLK_PM) += blk-pm.o obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += blk-crypto.o blk-crypto-profile.o \ diff --git a/block/blk-nvmem.c b/block/blk-nvmem.c new file mode 100644 index 0000000000000..8238511049f56 --- /dev/null +++ b/block/blk-nvmem.c @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * block device NVMEM provider + * + * Copyright (c) 2023 Daniel Golle <daniel@makrotopia.org> + * + * Useful on devices using a partition on an eMMC for MAC addresses or + * Wi-Fi calibration EEPROM data. + */ + +#include "blk.h" +#include <linux/nvmem-provider.h> +#include <linux/of.h> +#include <linux/pagemap.h> +#include <linux/property.h> + +/* List of all NVMEM devices */ +static LIST_HEAD(nvmem_devices); +static DEFINE_MUTEX(devices_mutex); + +struct blk_nvmem { + struct nvmem_device *nvmem; + struct block_device *bdev; + struct list_head list; +}; + +static int blk_nvmem_reg_read(void *priv, unsigned int from, + void *val, size_t bytes) +{ + pgoff_t f_index = from >> PAGE_SHIFT; + struct address_space *mapping; + struct blk_nvmem *bnv = priv; + size_t bytes_left = bytes; + struct folio *folio; + unsigned long offs, to_read; + void *p; + + if (!bnv->bdev) + return -ENODEV; + + offs = from & ((1 << PAGE_SHIFT) - 1); + mapping = bnv->bdev->bd_inode->i_mapping; + + while (bytes_left) { + folio = read_mapping_folio(mapping, f_index++, NULL); + if (IS_ERR(folio)) + return PTR_ERR(folio); + + to_read = min_t(unsigned long, bytes_left, PAGE_SIZE - offs); + p = folio_address(folio) + offset_in_folio(folio, offs); + memcpy(val, p, to_read); + offs = 0; + bytes_left -= to_read; + val += to_read; + folio_put(folio); + } + + return bytes_left == 0 ? 0 : -EIO; +} + +void blk_register_nvmem(struct block_device *bdev) +{ + struct fwnode_handle *fw_parts = NULL, *fw_part_c, *fw_part = NULL; + struct nvmem_config config = {}; + const char *partname, *uuid; + struct device *dev, *p0dev; + struct blk_nvmem *bnv; + u32 reg; + + /* + * skip devices which set GENHD_FL_NO_NVMEM + * + * This flag is used for mtdblock and ubiblock devices because + * both, MTD and UBI already implement their own NVMEM provider. + * To avoid registering multiple NVMEM providers for the same + * device node, skip the block NVMEM provider. + */ + if (bdev->bd_disk->flags & GENHD_FL_NO_NVMEM) + return; + + /* skip too large devices */ + if (bdev_nr_bytes(bdev) > INT_MAX) + return; + + dev = &bdev->bd_device; + if (!bdev_is_partition(bdev)) { + fw_part = dev->fwnode; + + if (!fw_part && dev->parent) + fw_part = dev->parent->fwnode; + + goto no_parts; + } + + p0dev = &bdev->bd_disk->part0->bd_device; + fw_parts = device_get_named_child_node(p0dev, "partitions"); + if (!fw_parts) + fw_parts = device_get_named_child_node(p0dev->parent, "partitions"); + + if (!fw_parts) + return; + + fwnode_for_each_child_node(fw_parts, fw_part_c) { + if (!fwnode_property_read_string(fw_part_c, "uuid", &uuid) && + (!bdev->bd_meta_info || strncmp(uuid, + bdev->bd_meta_info->uuid, + PARTITION_META_INFO_UUIDLTH))) + continue; + + if (!fwnode_property_read_string(fw_part_c, "partname", &partname) && + (!bdev->bd_meta_info || strncmp(partname, + bdev->bd_meta_info->volname, + PARTITION_META_INFO_VOLNAMELTH))) + continue; + + /* + * partition addresses (reg) in device tree greater than + * DISK_MAX_PARTS can be used to match uuid or partname only + */ + if (!fwnode_property_read_u32(fw_part_c, "reg", ®) && + reg < DISK_MAX_PARTS && bdev->bd_partno != reg) + continue; + + fw_part = fw_part_c; + break; + } + +no_parts: + if (!fwnode_device_is_compatible(fw_part, "nvmem-cells")) + return; + + bnv = kzalloc(sizeof(struct blk_nvmem), GFP_KERNEL); + if (!bnv) + return; + + config.id = NVMEM_DEVID_NONE; + config.dev = &bdev->bd_device; + config.name = dev_name(&bdev->bd_device); + config.owner = THIS_MODULE; + config.priv = bnv; + config.reg_read = blk_nvmem_reg_read; + config.size = bdev_nr_bytes(bdev); + config.word_size = 1; + config.stride = 1; + config.read_only = true; + config.root_only = true; + config.ignore_wp = true; + config.of_node = to_of_node(fw_part); + + bnv->bdev = bdev; + bnv->nvmem = nvmem_register(&config); + if (IS_ERR(bnv->nvmem)) { + /* Just ignore if there is no NVMEM support in the kernel */ + if (PTR_ERR(bnv->nvmem) != -EOPNOTSUPP) + dev_err_probe(&bdev->bd_device, PTR_ERR(bnv->nvmem), + "Failed to register NVMEM device\n"); + + kfree(bnv); + return; + } + + mutex_lock(&devices_mutex); + list_add_tail(&bnv->list, &nvmem_devices); + mutex_unlock(&devices_mutex); +} + +void blk_unregister_nvmem(struct block_device *bdev) +{ + struct blk_nvmem *bnv_c, *bnv = NULL; + + mutex_lock(&devices_mutex); + list_for_each_entry(bnv_c, &nvmem_devices, list) + if (bnv_c->bdev == bdev) { + bnv = bnv_c; + break; + } + + if (!bnv) { + mutex_unlock(&devices_mutex); + return; + } + + list_del(&bnv->list); + mutex_unlock(&devices_mutex); + nvmem_unregister(bnv->nvmem); + kfree(bnv); +} diff --git a/block/blk.h b/block/blk.h index 686712e138352..7423d0d5494e9 100644 --- a/block/blk.h +++ b/block/blk.h @@ -515,4 +515,17 @@ static inline int req_ref_read(struct request *req) return atomic_read(&req->ref); } +#ifdef CONFIG_BLK_NVMEM +void blk_register_nvmem(struct block_device *bdev); +void blk_unregister_nvmem(struct block_device *bdev); +#else +static inline void blk_register_nvmem(struct block_device *bdev) +{ +} + +static inline void blk_unregister_nvmem(struct block_device *bdev) +{ +} +#endif + #endif /* BLK_INTERNAL_H */ diff --git a/block/genhd.c b/block/genhd.c index 3d287b32d50df..b306e0f407bb2 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -527,6 +527,7 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk, disk_update_readahead(disk); disk_add_events(disk); set_bit(GD_ADDED, &disk->state); + blk_register_nvmem(disk->part0); return 0; out_unregister_bdi: @@ -569,6 +570,7 @@ static void blk_report_disk_dead(struct gendisk *disk) if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead) bdev->bd_holder_ops->mark_dead(bdev); mutex_unlock(&bdev->bd_holder_lock); + blk_unregister_nvmem(bdev); put_device(&bdev->bd_device); rcu_read_lock(); diff --git a/block/partitions/core.c b/block/partitions/core.c index 13a7341299a91..68bd655f5e68e 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -404,6 +404,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno, /* suppress uevent if the disk suppresses it */ if (!dev_get_uevent_suppress(ddev)) kobject_uevent(&pdev->kobj, KOBJ_ADD); + + blk_register_nvmem(bdev); return bdev; out_del:
On embedded devices using an eMMC it is common that one or more partitions on the eMMC are used to store MAC addresses and Wi-Fi calibration EEPROM data. Allow referencing the partition in device tree for the kernel and Wi-Fi drivers accessing it via the NVMEM layer. Signed-off-by: Daniel Golle <daniel@makrotopia.org> --- block/Kconfig | 8 ++ block/Makefile | 1 + block/blk-nvmem.c | 187 ++++++++++++++++++++++++++++++++++++++++ block/blk.h | 13 +++ block/genhd.c | 2 + block/partitions/core.c | 2 + 6 files changed, 213 insertions(+) create mode 100644 block/blk-nvmem.c