drivers/nvmem/brcm_nvram.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
   4  */
   5
   6 #include <linux/bcm47xx_nvram.h>
   7 #include <linux/etherdevice.h>
   8 #include <linux/if_ether.h>
   9 #include <linux/io.h>
  10 #include <linux/mod_devicetable.h>
  11 #include <linux/module.h>
  12 #include <linux/nvmem-consumer.h>
  13 #include <linux/nvmem-provider.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/slab.h>
  17
  18 #define NVRAM_MAGIC                     "FLSH"
  19
  20 /**
  21  * struct brcm_nvram - driver state internal struct
  22  *
  23  * @dev:                NVMEM device pointer
  24  * @nvmem_size:         Size of the whole space available for NVRAM
  25  * @data:               NVRAM data copy stored to avoid poking underlaying flash controller
  26  * @data_len:           NVRAM data size
  27  * @padding_byte:       Padding value used to fill remaining space
  28  * @cells:              Array of discovered NVMEM cells
  29  * @ncells:             Number of elements in cells
  30  */
  31 struct brcm_nvram {
  32         struct device *dev;
  33         size_t nvmem_size;
  34         uint8_t *data;
  35         size_t data_len;
  36         uint8_t padding_byte;
  37         struct nvmem_cell_info *cells;
  38         int ncells;
  39 };
  40
  41 struct brcm_nvram_header {
  42         char magic[4];
  43         __le32 len;
  44         __le32 crc_ver_init;    /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
  45         __le32 config_refresh;  /* 0:15 sdram_config, 16:31 sdram_refresh */
  46         __le32 config_ncdl;     /* ncdl values for memc */
  47 };
  48
  49 static int brcm_nvram_read(void *context, unsigned int offset, void *val,
  50                            size_t bytes)
  51 {
  52         struct brcm_nvram *priv = context;
  53         size_t to_copy;
  54
  55         if (offset + bytes > priv->data_len)
  56                 to_copy = max_t(ssize_t, (ssize_t)priv->data_len - offset, 0);
  57         else
  58                 to_copy = bytes;
  59
  60         memcpy(val, priv->data + offset, to_copy);
  61
  62         memset((uint8_t *)val + to_copy, priv->padding_byte, bytes - to_copy);
  63
  64         return 0;
  65 }
  66
  67 static int brcm_nvram_copy_data(struct brcm_nvram *priv, struct platform_device *pdev)
  68 {
  69         struct resource *res;
  70         void __iomem *base;
  71
  72         base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
  73         if (IS_ERR(base))
  74                 return PTR_ERR(base);
  75
  76         priv->nvmem_size = resource_size(res);
  77
  78         priv->padding_byte = readb(base + priv->nvmem_size - 1);
  79         for (priv->data_len = priv->nvmem_size;
  80              priv->data_len;
  81              priv->data_len--) {
  82                 if (readb(base + priv->data_len - 1) != priv->padding_byte)
  83                         break;
  84         }
  85         WARN(priv->data_len > SZ_128K, "Unexpected (big) NVRAM size: %zu B\n", priv->data_len);
  86
  87         priv->data = devm_kzalloc(priv->dev, priv->data_len, GFP_KERNEL);
  88         if (!priv->data)
  89                 return -ENOMEM;
  90
  91         memcpy_fromio(priv->data, base, priv->data_len);
  92
  93         bcm47xx_nvram_init_from_iomem(base, priv->data_len);
  94
  95         return 0;
  96 }
  97
  98 static int brcm_nvram_read_post_process_macaddr(void *context, const char *id, int index,
  99                                                 unsigned int offset, void *buf, size_t bytes)
 100 {
 101         u8 mac[ETH_ALEN];
 102
 103         if (bytes != 3 * ETH_ALEN - 1)
 104                 return -EINVAL;
 105
 106         if (!mac_pton(buf, mac))
 107                 return -EINVAL;
 108
 109         if (index)
 110                 eth_addr_add(mac, index);
 111
 112         ether_addr_copy(buf, mac);
 113
 114         return 0;
 115 }
 116
 117 static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
 118                                 size_t len)
 119 {
 120         struct device *dev = priv->dev;
 121         char *var, *value;
 122         uint8_t tmp;
 123         int idx;
 124         int err = 0;
 125
 126         tmp = priv->data[len - 1];
 127         priv->data[len - 1] = '\0';
 128
 129         priv->ncells = 0;
 130         for (var = data + sizeof(struct brcm_nvram_header);
 131              var < (char *)data + len && *var;
 132              var += strlen(var) + 1) {
 133                 priv->ncells++;
 134         }
 135
 136         priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
 137         if (!priv->cells) {
 138                 err = -ENOMEM;
 139                 goto out;
 140         }
 141
 142         for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
 143              var < (char *)data + len && *var;
 144              var = value + strlen(value) + 1, idx++) {
 145                 char *eq, *name;
 146
 147                 eq = strchr(var, '=');
 148                 if (!eq)
 149                         break;
 150                 *eq = '\0';
 151                 name = devm_kstrdup(dev, var, GFP_KERNEL);
 152                 *eq = '=';
 153                 if (!name) {
 154                         err = -ENOMEM;
 155                         goto out;
 156                 }
 157                 value = eq + 1;
 158
 159                 priv->cells[idx].name = name;
 160                 priv->cells[idx].offset = value - (char *)data;
 161                 priv->cells[idx].bytes = strlen(value);
 162                 priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
 163                 if (!strcmp(name, "et0macaddr") ||
 164                     !strcmp(name, "et1macaddr") ||
 165                     !strcmp(name, "et2macaddr")) {
 166                         priv->cells[idx].raw_len = strlen(value);
 167                         priv->cells[idx].bytes = ETH_ALEN;
 168                         priv->cells[idx].read_post_process = brcm_nvram_read_post_process_macaddr;
 169                 }
 170         }
 171
 172 out:
 173         priv->data[len - 1] = tmp;
 174         return err;
 175 }
 176
 177 static int brcm_nvram_parse(struct brcm_nvram *priv)
 178 {
 179         struct brcm_nvram_header *header = (struct brcm_nvram_header *)priv->data;
 180         struct device *dev = priv->dev;
 181         size_t len;
 182         int err;
 183
 184         if (memcmp(header->magic, NVRAM_MAGIC, 4)) {
 185                 dev_err(dev, "Invalid NVRAM magic\n");
 186                 return -EINVAL;
 187         }
 188
 189         len = le32_to_cpu(header->len);
 190         if (len > priv->nvmem_size) {
 191                 dev_err(dev, "NVRAM length (%zd) exceeds mapped size (%zd)\n", len,
 192                         priv->nvmem_size);
 193                 return -EINVAL;
 194         }
 195
 196         err = brcm_nvram_add_cells(priv, priv->data, len);
 197         if (err)
 198                 dev_err(dev, "Failed to add cells: %d\n", err);
 199
 200         return 0;
 201 }
 202
 203 static int brcm_nvram_probe(struct platform_device *pdev)
 204 {
 205         struct nvmem_config config = {
 206                 .name = "brcm-nvram",
 207                 .reg_read = brcm_nvram_read,
 208         };
 209         struct device *dev = &pdev->dev;
 210         struct brcm_nvram *priv;
 211         int err;
 212
 213         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 214         if (!priv)
 215                 return -ENOMEM;
 216         priv->dev = dev;
 217
 218         err = brcm_nvram_copy_data(priv, pdev);
 219         if (err)
 220                 return err;
 221
 222         err = brcm_nvram_parse(priv);
 223         if (err)
 224                 return err;
 225
 226         config.dev = dev;
 227         config.cells = priv->cells;
 228         config.ncells = priv->ncells;
 229         config.priv = priv;
 230         config.size = priv->nvmem_size;
 231
 232         return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
 233 }
 234
 235 static const struct of_device_id brcm_nvram_of_match_table[] = {
 236         { .compatible = "brcm,nvram", },
 237         {},
 238 };
 239
 240 static struct platform_driver brcm_nvram_driver = {
 241         .probe = brcm_nvram_probe,
 242         .driver = {
 243                 .name = "brcm_nvram",
 244                 .of_match_table = brcm_nvram_of_match_table,
 245         },
 246 };
 247
 248 static int __init brcm_nvram_init(void)
 249 {
 250         return platform_driver_register(&brcm_nvram_driver);
 251 }
 252
 253 subsys_initcall_sync(brcm_nvram_init);
 254
 255 MODULE_AUTHOR("Rafał Miłecki");
 256 MODULE_LICENSE("GPL");
 257 MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);