drivers/mtd/ubi/nvmem.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) 2023 Daniel Golle <daniel@makrotopia.org>
   4  */
   5
   6 /* UBI NVMEM provider */
   7 #include "ubi.h"
   8 #include <linux/nvmem-provider.h>
   9 #include <asm/div64.h>
  10
  11 /* List of all NVMEM devices */
  12 static LIST_HEAD(nvmem_devices);
  13 static DEFINE_MUTEX(devices_mutex);
  14
  15 struct ubi_nvmem {
  16         struct nvmem_device *nvmem;
  17         int ubi_num;
  18         int vol_id;
  19         int usable_leb_size;
  20         struct list_head list;
  21 };
  22
  23 static int ubi_nvmem_reg_read(void *priv, unsigned int from,
  24                               void *val, size_t bytes)
  25 {
  26         size_t to_read, bytes_left = bytes;
  27         struct ubi_nvmem *unv = priv;
  28         struct ubi_volume_desc *desc;
  29         uint32_t offs;
  30         uint64_t lnum = from;
  31         int err = 0;
  32
  33         desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
  34         if (IS_ERR(desc))
  35                 return PTR_ERR(desc);
  36
  37         offs = do_div(lnum, unv->usable_leb_size);
  38         while (bytes_left) {
  39                 to_read = unv->usable_leb_size - offs;
  40
  41                 if (to_read > bytes_left)
  42                         to_read = bytes_left;
  43
  44                 err = ubi_read(desc, lnum, val, offs, to_read);
  45                 if (err)
  46                         break;
  47
  48                 lnum += 1;
  49                 offs = 0;
  50                 bytes_left -= to_read;
  51                 val += to_read;
  52         }
  53         ubi_close_volume(desc);
  54
  55         if (err)
  56                 return err;
  57
  58         return bytes_left == 0 ? 0 : -EIO;
  59 }
  60
  61 static int ubi_nvmem_add(struct ubi_volume_info *vi)
  62 {
  63         struct device_node *np = dev_of_node(vi->dev);
  64         struct nvmem_config config = {};
  65         struct ubi_nvmem *unv;
  66         int ret;
  67
  68         if (!np)
  69                 return 0;
  70
  71         if (!of_get_child_by_name(np, "nvmem-layout"))
  72                 return 0;
  73
  74         if (WARN_ON_ONCE(vi->usable_leb_size <= 0) ||
  75             WARN_ON_ONCE(vi->size <= 0))
  76                 return -EINVAL;
  77
  78         unv = kzalloc(sizeof(struct ubi_nvmem), GFP_KERNEL);
  79         if (!unv)
  80                 return -ENOMEM;
  81
  82         config.id = NVMEM_DEVID_NONE;
  83         config.dev = vi->dev;
  84         config.name = dev_name(vi->dev);
  85         config.owner = THIS_MODULE;
  86         config.priv = unv;
  87         config.reg_read = ubi_nvmem_reg_read;
  88         config.size = vi->usable_leb_size * vi->size;
  89         config.word_size = 1;
  90         config.stride = 1;
  91         config.read_only = true;
  92         config.root_only = true;
  93         config.ignore_wp = true;
  94         config.of_node = np;
  95
  96         unv->ubi_num = vi->ubi_num;
  97         unv->vol_id = vi->vol_id;
  98         unv->usable_leb_size = vi->usable_leb_size;
  99         unv->nvmem = nvmem_register(&config);
 100         if (IS_ERR(unv->nvmem)) {
 101                 ret = dev_err_probe(vi->dev, PTR_ERR(unv->nvmem),
 102                                     "Failed to register NVMEM device\n");
 103                 kfree(unv);
 104                 return ret;
 105         }
 106
 107         mutex_lock(&devices_mutex);
 108         list_add_tail(&unv->list, &nvmem_devices);
 109         mutex_unlock(&devices_mutex);
 110
 111         return 0;
 112 }
 113
 114 static void ubi_nvmem_remove(struct ubi_volume_info *vi)
 115 {
 116         struct ubi_nvmem *unv_c, *unv = NULL;
 117
 118         mutex_lock(&devices_mutex);
 119         list_for_each_entry(unv_c, &nvmem_devices, list)
 120                 if (unv_c->ubi_num == vi->ubi_num && unv_c->vol_id == vi->vol_id) {
 121                         unv = unv_c;
 122                         break;
 123                 }
 124
 125         if (!unv) {
 126                 mutex_unlock(&devices_mutex);
 127                 return;
 128         }
 129
 130         list_del(&unv->list);
 131         mutex_unlock(&devices_mutex);
 132         nvmem_unregister(unv->nvmem);
 133         kfree(unv);
 134 }
 135
 136 /**
 137  * nvmem_notify - UBI notification handler.
 138  * @nb: registered notifier block
 139  * @l: notification type
 140  * @ns_ptr: pointer to the &struct ubi_notification object
 141  */
 142 static int nvmem_notify(struct notifier_block *nb, unsigned long l,
 143                          void *ns_ptr)
 144 {
 145         struct ubi_notification *nt = ns_ptr;
 146
 147         switch (l) {
 148         case UBI_VOLUME_RESIZED:
 149                 ubi_nvmem_remove(&nt->vi);
 150                 fallthrough;
 151         case UBI_VOLUME_ADDED:
 152                 ubi_nvmem_add(&nt->vi);
 153                 break;
 154         case UBI_VOLUME_SHUTDOWN:
 155                 ubi_nvmem_remove(&nt->vi);
 156                 break;
 157         default:
 158                 break;
 159         }
 160         return NOTIFY_OK;
 161 }
 162
 163 static struct notifier_block nvmem_notifier = {
 164         .notifier_call = nvmem_notify,
 165 };
 166
 167 static int __init ubi_nvmem_init(void)
 168 {
 169         return ubi_register_volume_notifier(&nvmem_notifier, 0);
 170 }
 171
 172 static void __exit ubi_nvmem_exit(void)
 173 {
 174         struct ubi_nvmem *unv, *tmp;
 175
 176         mutex_lock(&devices_mutex);
 177         list_for_each_entry_safe(unv, tmp, &nvmem_devices, list) {
 178                 nvmem_unregister(unv->nvmem);
 179                 list_del(&unv->list);
 180                 kfree(unv);
 181         }
 182         mutex_unlock(&devices_mutex);
 183
 184         ubi_unregister_volume_notifier(&nvmem_notifier);
 185 }
 186
 187 module_init(ubi_nvmem_init);
 188 module_exit(ubi_nvmem_exit);
 189 MODULE_DESCRIPTION("NVMEM layer over UBI volumes");
 190 MODULE_AUTHOR("Daniel Golle");
 191 MODULE_LICENSE("GPL");