Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
mtd: ubi: provide NVMEM layer over UBI volumes
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 <daniel@makrotopia.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
authored by
Daniel Golle
and committed by
Richard Weinberger
3ce48580
51932f9f
+202
+13
drivers/mtd/ubi/Kconfig
+13
drivers/mtd/ubi/Kconfig
···
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testing purposes.
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If in doubt, say "N".
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config MTD_UBI_NVMEM
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tristate "UBI virtual NVMEM"
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default n
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depends on NVMEM
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help
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This option enabled an additional driver exposing UBI volumes as NVMEM
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providers, intended for platforms where UBI is part of the firmware
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specification and used to store also e.g. MAC addresses or board-
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specific Wi-Fi calibration data.
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If in doubt, say "N".
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endif # MTD_UBI
+1
drivers/mtd/ubi/Makefile
+1
drivers/mtd/ubi/Makefile
+188
drivers/mtd/ubi/nvmem.c
+188
drivers/mtd/ubi/nvmem.c
···
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (c) 2023 Daniel Golle <daniel@makrotopia.org>
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*/
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/* UBI NVMEM provider */
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#include "ubi.h"
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#include <linux/nvmem-provider.h>
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#include <asm/div64.h>
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/* List of all NVMEM devices */
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static LIST_HEAD(nvmem_devices);
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static DEFINE_MUTEX(devices_mutex);
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struct ubi_nvmem {
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struct nvmem_device *nvmem;
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int ubi_num;
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int vol_id;
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int usable_leb_size;
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struct list_head list;
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};
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static int ubi_nvmem_reg_read(void *priv, unsigned int from,
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void *val, size_t bytes)
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{
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int err = 0, lnum = from, offs, bytes_left = bytes, to_read;
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struct ubi_nvmem *unv = priv;
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struct ubi_volume_desc *desc;
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desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
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if (IS_ERR(desc))
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return PTR_ERR(desc);
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+
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offs = do_div(lnum, unv->usable_leb_size);
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while (bytes_left) {
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to_read = unv->usable_leb_size - offs;
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if (to_read > bytes_left)
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to_read = bytes_left;
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err = ubi_read(desc, lnum, val, offs, to_read);
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if (err)
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break;
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lnum += 1;
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offs = 0;
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bytes_left -= to_read;
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val += to_read;
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}
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ubi_close_volume(desc);
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if (err)
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return err;
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return bytes_left == 0 ? 0 : -EIO;
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}
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static int ubi_nvmem_add(struct ubi_volume_info *vi)
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{
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struct device_node *np = dev_of_node(vi->dev);
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struct nvmem_config config = {};
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struct ubi_nvmem *unv;
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int ret;
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if (!np)
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return 0;
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if (!of_get_child_by_name(np, "nvmem-layout"))
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return 0;
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if (WARN_ON_ONCE(vi->usable_leb_size <= 0) ||
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WARN_ON_ONCE(vi->size <= 0))
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return -EINVAL;
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unv = kzalloc(sizeof(struct ubi_nvmem), GFP_KERNEL);
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if (!unv)
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return -ENOMEM;
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config.id = NVMEM_DEVID_NONE;
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config.dev = vi->dev;
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config.name = dev_name(vi->dev);
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config.owner = THIS_MODULE;
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config.priv = unv;
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config.reg_read = ubi_nvmem_reg_read;
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config.size = vi->usable_leb_size * vi->size;
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config.word_size = 1;
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config.stride = 1;
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config.read_only = true;
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config.root_only = true;
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config.ignore_wp = true;
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config.of_node = np;
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unv->ubi_num = vi->ubi_num;
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unv->vol_id = vi->vol_id;
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unv->usable_leb_size = vi->usable_leb_size;
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unv->nvmem = nvmem_register(&config);
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if (IS_ERR(unv->nvmem)) {
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ret = dev_err_probe(vi->dev, PTR_ERR(unv->nvmem),
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"Failed to register NVMEM device\n");
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kfree(unv);
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return ret;
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}
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mutex_lock(&devices_mutex);
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list_add_tail(&unv->list, &nvmem_devices);
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mutex_unlock(&devices_mutex);
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return 0;
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}
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static void ubi_nvmem_remove(struct ubi_volume_info *vi)
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{
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struct ubi_nvmem *unv_c, *unv = NULL;
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mutex_lock(&devices_mutex);
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list_for_each_entry(unv_c, &nvmem_devices, list)
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if (unv_c->ubi_num == vi->ubi_num && unv_c->vol_id == vi->vol_id) {
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unv = unv_c;
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break;
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}
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if (!unv) {
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mutex_unlock(&devices_mutex);
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return;
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}
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list_del(&unv->list);
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mutex_unlock(&devices_mutex);
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nvmem_unregister(unv->nvmem);
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kfree(unv);
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}
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/**
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* nvmem_notify - UBI notification handler.
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* @nb: registered notifier block
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* @l: notification type
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* @ns_ptr: pointer to the &struct ubi_notification object
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*/
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static int nvmem_notify(struct notifier_block *nb, unsigned long l,
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void *ns_ptr)
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{
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struct ubi_notification *nt = ns_ptr;
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switch (l) {
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case UBI_VOLUME_RESIZED:
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ubi_nvmem_remove(&nt->vi);
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fallthrough;
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case UBI_VOLUME_ADDED:
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ubi_nvmem_add(&nt->vi);
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break;
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case UBI_VOLUME_SHUTDOWN:
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ubi_nvmem_remove(&nt->vi);
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break;
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default:
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block nvmem_notifier = {
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.notifier_call = nvmem_notify,
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};
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static int __init ubi_nvmem_init(void)
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{
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return ubi_register_volume_notifier(&nvmem_notifier, 0);
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}
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static void __exit ubi_nvmem_exit(void)
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{
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struct ubi_nvmem *unv, *tmp;
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mutex_lock(&devices_mutex);
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list_for_each_entry_safe(unv, tmp, &nvmem_devices, list) {
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nvmem_unregister(unv->nvmem);
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list_del(&unv->list);
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kfree(unv);
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}
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mutex_unlock(&devices_mutex);
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ubi_unregister_volume_notifier(&nvmem_notifier);
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}
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module_init(ubi_nvmem_init);
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module_exit(ubi_nvmem_exit);
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MODULE_DESCRIPTION("NVMEM layer over UBI volumes");
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MODULE_AUTHOR("Daniel Golle");
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MODULE_LICENSE("GPL");