The series is a follow-up and contains all patches of the previous
series "mtd: ubi: behave like a good MTD citizen"[1] which was meant in
preparation for implementing the NVMEM provider.
The goal is to support embedded Linux devices which got NVMEM bits
stored inside a UBI volume. Representing the UBI volume in the Device
Tree, adding a phandle to be referenced by NVMEM consumers allows such
devices to come up with their correct MAC addresses and device-specific
Wi-Fi calibration data loaded.
In order to be available for other drivers, attaching UBI devices has
to be moved from late_initcall (which is too late for other drivers) to
happen earlier. As an alternative to the existing kernel cmdline
parameter the Device Tree property 'compatible = "linux,ubi";' inside
an MTD partition can be used to have that MTD device attached as UBI
device. MTD partitions which serve as UBI devices may have a "volumes"
firmware subnode with volumes which may be compatible with
"nvmem-cells".
In this way, other drivers (think: Ethernet, Wi-Fi) can resolve and
acquire NVMEM bits using the usual device tree phandle, just this time
the NVMEM content is read from a UBI volume.
[1]: https://patchwork.ozlabs.org/project/linux-mtd/list/?series=353177&state=%2A&archive=both
Daniel Golle (6):
mtd: ubi: block: don't return on error when removing
mtd: ubi: block: use notifier to create ubiblock from parameter
mtd: ubi: attach MTD partition from device-tree
mtd: ubi: introduce pre-removal notification for UBI volumes
mtd: ubi: populate ubi volume fwnode
mtd: ubi: provide NVMEM layer over UBI volumes
drivers/mtd/ubi/Kconfig | 12 +++
drivers/mtd/ubi/Makefile | 1 +
drivers/mtd/ubi/block.c | 186 +++++++++++++++++++++++---------------
drivers/mtd/ubi/build.c | 160 ++++++++++++++++++++++++---------
drivers/mtd/ubi/cdev.c | 4 +-
drivers/mtd/ubi/nvmem.c | 189 +++++++++++++++++++++++++++++++++++++++
drivers/mtd/ubi/ubi.h | 6 +-
drivers/mtd/ubi/vmt.c | 36 ++++++++
include/linux/mtd/ubi.h | 2 +
9 files changed, 477 insertions(+), 119 deletions(-)
create mode 100644 drivers/mtd/ubi/nvmem.c
--
2.41.0
Look for the 'volumes' subnode of an MTD partition attached to a UBI
device and attach matching child nodes to UBI volumes.
This allows UBI volumes to be referenced in device tree, e.g. for use
as NVMEM providers.
Signed-off-by: Daniel Golle <[email protected]>
---
drivers/mtd/ubi/vmt.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index eed4b57c61bda..3b997256cfba7 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -124,6 +124,35 @@ static void vol_release(struct device *dev)
kfree(vol);
}
+static struct fwnode_handle *find_volume_fwnode(struct ubi_volume *vol)
+{
+ struct fwnode_handle *fw_vols, *fw_vol;
+ const char *volname;
+ u32 reg;
+
+ fw_vols = device_get_named_child_node(vol->dev.parent->parent, "volumes");
+ if (!fw_vols)
+ return NULL;
+
+ fwnode_for_each_child_node(fw_vols, fw_vol) {
+ if (!fwnode_property_read_string(fw_vol, "volname", &volname) &&
+ strncmp(volname, vol->name, vol->name_len))
+ continue;
+
+ /*
+ * volume id (reg) in device tree greater than UBI_MAX_VOLUMES
+ * can be used to match by volname only
+ */
+ if (!fwnode_property_read_u32(fw_vol, "reg", ®) &&
+ reg < UBI_MAX_VOLUMES && vol->vol_id != reg)
+ continue;
+
+ return fw_vol;
+ }
+
+ return NULL;
+}
+
/**
* ubi_create_volume - create volume.
* @ubi: UBI device description object
@@ -223,6 +252,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
vol->name_len = req->name_len;
memcpy(vol->name, req->name, vol->name_len);
vol->ubi = ubi;
+ device_set_node(&vol->dev, find_volume_fwnode(vol));
/*
* Finish all pending erases because there may be some LEBs belonging
@@ -597,6 +627,7 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
vol->dev.class = &ubi_class;
vol->dev.groups = volume_dev_groups;
dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
+ device_set_node(&vol->dev, find_volume_fwnode(vol));
err = device_register(&vol->dev);
if (err) {
cdev_del(&vol->cdev);
--
2.41.0
In an ideal world we would like UBI to be used where ever possible on a
NAND chip. And with UBI support in ARM Trusted Firmware and U-Boot it
is possible to achieve an (almost-)all-UBI flash layout. Hence the need
for a way to also use UBI volumes to store board-level constants, such
as MAC addresses and calibration data of wireless interfaces.
Add UBI volume NVMEM driver module exposing UBI volumes as NVMEM
providers. Allow UBI devices to have a "volumes" firmware subnode with
volumes which may be compatible with "nvmem-cells".
Access to UBI volumes via the NVMEM interface at this point is
read-only, and it is slow, opening and closing the UBI volume for each
access due to limitations of the NVMEM provider API.
Signed-off-by: Daniel Golle <[email protected]>
---
drivers/mtd/ubi/Kconfig | 12 +++
drivers/mtd/ubi/Makefile | 1 +
drivers/mtd/ubi/nvmem.c | 189 +++++++++++++++++++++++++++++++++++++++
3 files changed, 202 insertions(+)
create mode 100644 drivers/mtd/ubi/nvmem.c
diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 2ed77b7b3fcb5..45d939bbfa853 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -104,4 +104,16 @@ config MTD_UBI_BLOCK
If in doubt, say "N".
+config MTD_UBI_NVMEM
+ tristate "UBI virtual NVMEM"
+ default n
+ depends on NVMEM
+ help
+ This option enabled an additional driver exposing UBI volumes as NVMEM
+ providers, intended for platforms where UBI is part of the firmware
+ specification and used to store also e.g. MAC addresses or board-
+ specific Wi-Fi calibration data.
+
+ If in doubt, say "N".
+
endif # MTD_UBI
diff --git a/drivers/mtd/ubi/Makefile b/drivers/mtd/ubi/Makefile
index 543673605ca72..4b51aaf00d1a2 100644
--- a/drivers/mtd/ubi/Makefile
+++ b/drivers/mtd/ubi/Makefile
@@ -7,3 +7,4 @@ ubi-$(CONFIG_MTD_UBI_FASTMAP) += fastmap.o
ubi-$(CONFIG_MTD_UBI_BLOCK) += block.o
obj-$(CONFIG_MTD_UBI_GLUEBI) += gluebi.o
+obj-$(CONFIG_MTD_UBI_NVMEM) += nvmem.o
diff --git a/drivers/mtd/ubi/nvmem.c b/drivers/mtd/ubi/nvmem.c
new file mode 100644
index 0000000000000..dd7cc6afb8d00
--- /dev/null
+++ b/drivers/mtd/ubi/nvmem.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023 Daniel Golle <[email protected]>
+ */
+
+/* UBI NVMEM provider */
+#include "ubi.h"
+#include <linux/nvmem-provider.h>
+
+/* List of all NVMEM devices */
+static LIST_HEAD(nvmem_devices);
+static DEFINE_MUTEX(devices_mutex);
+
+struct ubi_nvmem {
+ struct nvmem_device *nvmem;
+ int ubi_num;
+ int vol_id;
+ int usable_leb_size;
+ struct list_head list;
+};
+
+static int ubi_nvmem_reg_read(void *priv, unsigned int from,
+ void *val, size_t bytes)
+{
+ struct ubi_nvmem *unv = priv;
+ struct ubi_volume_desc *desc;
+ int err = 0, lnum, offs, bytes_left;
+ size_t to_read;
+
+ desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
+ if (IS_ERR(desc))
+ return PTR_ERR(desc);
+
+ lnum = div_u64_rem(from, unv->usable_leb_size, &offs);
+ bytes_left = bytes;
+ while (bytes_left) {
+ to_read = unv->usable_leb_size - offs;
+
+ if (to_read > bytes_left)
+ to_read = bytes_left;
+
+ err = ubi_read(desc, lnum, val, offs, to_read);
+ if (err)
+ break;
+
+ lnum += 1;
+ offs = 0;
+ bytes_left -= to_read;
+ val += to_read;
+ }
+ ubi_close_volume(desc);
+
+ if (err)
+ return err;
+
+ return bytes_left == 0 ? 0 : -EIO;
+}
+
+static int ubi_nvmem_add(struct ubi_volume_info *vi)
+{
+ struct nvmem_config config = {};
+ struct ubi_nvmem *unv;
+ int ret;
+
+ if (!device_is_compatible(vi->dev, "nvmem-cells"))
+ return 0;
+
+ unv = kzalloc(sizeof(struct ubi_nvmem), GFP_KERNEL);
+ if (!unv)
+ return -ENOMEM;
+
+ config.id = NVMEM_DEVID_NONE;
+ config.dev = vi->dev;
+ config.name = dev_name(vi->dev);
+ config.owner = THIS_MODULE;
+ config.priv = unv;
+ config.reg_read = ubi_nvmem_reg_read;
+ config.size = vi->usable_leb_size * vi->size;
+ config.word_size = 1;
+ config.stride = 1;
+ config.read_only = true;
+ config.root_only = true;
+ config.ignore_wp = true;
+ config.of_node = dev_of_node(vi->dev);
+
+ if (!config.of_node)
+ config.no_of_node = true;
+
+ unv->ubi_num = vi->ubi_num;
+ unv->vol_id = vi->vol_id;
+ unv->usable_leb_size = vi->usable_leb_size;
+ unv->nvmem = nvmem_register(&config);
+ if (IS_ERR(unv->nvmem)) {
+ /* Just ignore if there is no NVMEM support in the kernel */
+ if (PTR_ERR(unv->nvmem) == -EOPNOTSUPP)
+ ret = 0;
+ else
+ ret = dev_err_probe(vi->dev, PTR_ERR(unv->nvmem),
+ "Failed to register NVMEM device\n");
+
+ kfree(unv);
+ return ret;
+ }
+
+ mutex_lock(&devices_mutex);
+ list_add_tail(&unv->list, &nvmem_devices);
+ mutex_unlock(&devices_mutex);
+
+ return 0;
+}
+
+static void ubi_nvmem_remove(struct ubi_volume_info *vi)
+{
+ struct ubi_nvmem *unv_c, *unv = NULL;
+
+ mutex_lock(&devices_mutex);
+ list_for_each_entry(unv_c, &nvmem_devices, list)
+ if (unv_c->ubi_num == vi->ubi_num && unv_c->vol_id == vi->vol_id) {
+ unv = unv_c;
+ break;
+ }
+
+ if (!unv) {
+ mutex_unlock(&devices_mutex);
+ return;
+ }
+
+ list_del(&unv->list);
+ mutex_unlock(&devices_mutex);
+ nvmem_unregister(unv->nvmem);
+ kfree(unv);
+}
+
+/**
+ * nvmem_notify - UBI notification handler.
+ * @nb: registered notifier block
+ * @l: notification type
+ * @ns_ptr: pointer to the &struct ubi_notification object
+ */
+static int nvmem_notify(struct notifier_block *nb, unsigned long l,
+ void *ns_ptr)
+{
+ struct ubi_notification *nt = ns_ptr;
+
+ switch (l) {
+ case UBI_VOLUME_RESIZED:
+ ubi_nvmem_remove(&nt->vi);
+ fallthrough;
+ case UBI_VOLUME_ADDED:
+ ubi_nvmem_add(&nt->vi);
+ break;
+ case UBI_VOLUME_SHUTDOWN:
+ ubi_nvmem_remove(&nt->vi);
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block nvmem_notifier = {
+ .notifier_call = nvmem_notify,
+};
+
+static int __init ubi_nvmem_init(void)
+{
+ return ubi_register_volume_notifier(&nvmem_notifier, 0);
+}
+
+static void __exit ubi_nvmem_exit(void)
+{
+ struct ubi_nvmem *unv, *tmp;
+
+ mutex_lock(&devices_mutex);
+ list_for_each_entry_safe(unv, tmp, &nvmem_devices, list) {
+ nvmem_unregister(unv->nvmem);
+ list_del(&unv->list);
+ kfree(unv);
+ }
+ mutex_unlock(&devices_mutex);
+
+ ubi_unregister_volume_notifier(&nvmem_notifier);
+}
+
+module_init(ubi_nvmem_init);
+module_exit(ubi_nvmem_exit);
+MODULE_DESCRIPTION("NVMEM layer over UBI volumes");
+MODULE_AUTHOR("Daniel Golle");
+MODULE_LICENSE("GPL");
--
2.41.0
On 7/31/23 12:14, Daniel Golle wrote:
> diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
> index 2ed77b7b3fcb5..45d939bbfa853 100644
> --- a/drivers/mtd/ubi/Kconfig
> +++ b/drivers/mtd/ubi/Kconfig
> @@ -104,4 +104,16 @@ config MTD_UBI_BLOCK
>
> If in doubt, say "N".
>
> +config MTD_UBI_NVMEM
> + tristate "UBI virtual NVMEM"
> + default n
> + depends on NVMEM
> + help
> + This option enabled an additional driver exposing UBI volumes as NVMEM
enables
> + providers, intended for platforms where UBI is part of the firmware
> + specification and used to store also e.g. MAC addresses or board-
> + specific Wi-Fi calibration data.
> +
> + If in doubt, say "N".
and Kconfig help text should be indented with one tab + 2 spaces
according to coding-style.rst.
> +
> endif # MTD_UBI
--
~Randy