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/io.h>
   7 #include <linux/mod_devicetable.h>
   8 #include <linux/module.h>
   9 #include <linux/nvmem-consumer.h>
  10 #include <linux/nvmem-provider.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/slab.h>
  13
  14 #define NVRAM_MAGIC                     "FLSH"
  15
  16 struct brcm_nvram {
  17         struct device *dev;
  18         void __iomem *base;
  19         struct nvmem_cell_info *cells;
  20         int ncells;
  21 };
  22
  23 struct brcm_nvram_header {
  24         char magic[4];
  25         __le32 len;
  26         __le32 crc_ver_init;    /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
  27         __le32 config_refresh;  /* 0:15 sdram_config, 16:31 sdram_refresh */
  28         __le32 config_ncdl;     /* ncdl values for memc */
  29 };
  30
  31 static int brcm_nvram_read(void *context, unsigned int offset, void *val,
  32                            size_t bytes)
  33 {
  34         struct brcm_nvram *priv = context;
  35         u8 *dst = val;
  36
  37         while (bytes--)
  38                 *dst++ = readb(priv->base + offset++);
  39
  40         return 0;
  41 }
  42
  43 static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
  44                                 size_t len)
  45 {
  46         struct device *dev = priv->dev;
  47         char *var, *value, *eq;
  48         int idx;
  49
  50         priv->ncells = 0;
  51         for (var = data + sizeof(struct brcm_nvram_header);
  52              var < (char *)data + len && *var;
  53              var += strlen(var) + 1) {
  54                 priv->ncells++;
  55         }
  56
  57         priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
  58         if (!priv->cells)
  59                 return -ENOMEM;
  60
  61         for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
  62              var < (char *)data + len && *var;
  63              var = value + strlen(value) + 1, idx++) {
  64                 eq = strchr(var, '=');
  65                 if (!eq)
  66                         break;
  67                 *eq = '\0';
  68                 value = eq + 1;
  69
  70                 priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
  71                 if (!priv->cells[idx].name)
  72                         return -ENOMEM;
  73                 priv->cells[idx].offset = value - (char *)data;
  74                 priv->cells[idx].bytes = strlen(value);
  75         }
  76
  77         return 0;
  78 }
  79
  80 static int brcm_nvram_parse(struct brcm_nvram *priv)
  81 {
  82         struct device *dev = priv->dev;
  83         struct brcm_nvram_header header;
  84         uint8_t *data;
  85         size_t len;
  86         int err;
  87
  88         memcpy_fromio(&header, priv->base, sizeof(header));
  89
  90         if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
  91                 dev_err(dev, "Invalid NVRAM magic\n");
  92                 return -EINVAL;
  93         }
  94
  95         len = le32_to_cpu(header.len);
  96
  97         data = kcalloc(1, len, GFP_KERNEL);
  98         memcpy_fromio(data, priv->base, len);
  99         data[len - 1] = '\0';
 100
 101         err = brcm_nvram_add_cells(priv, data, len);
 102         if (err) {
 103                 dev_err(dev, "Failed to add cells: %d\n", err);
 104                 return err;
 105         }
 106
 107         kfree(data);
 108
 109         return 0;
 110 }
 111
 112 static int brcm_nvram_probe(struct platform_device *pdev)
 113 {
 114         struct nvmem_config config = {
 115                 .name = "brcm-nvram",
 116                 .reg_read = brcm_nvram_read,
 117         };
 118         struct device *dev = &pdev->dev;
 119         struct resource *res;
 120         struct brcm_nvram *priv;
 121         int err;
 122
 123         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 124         if (!priv)
 125                 return -ENOMEM;
 126         priv->dev = dev;
 127
 128         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 129         priv->base = devm_ioremap_resource(dev, res);
 130         if (IS_ERR(priv->base))
 131                 return PTR_ERR(priv->base);
 132
 133         err = brcm_nvram_parse(priv);
 134         if (err)
 135                 return err;
 136
 137         config.dev = dev;
 138         config.cells = priv->cells;
 139         config.ncells = priv->ncells;
 140         config.priv = priv;
 141         config.size = resource_size(res);
 142
 143         return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
 144 }
 145
 146 static const struct of_device_id brcm_nvram_of_match_table[] = {
 147         { .compatible = "brcm,nvram", },
 148         {},
 149 };
 150
 151 static struct platform_driver brcm_nvram_driver = {
 152         .probe = brcm_nvram_probe,
 153         .driver = {
 154                 .name = "brcm_nvram",
 155                 .of_match_table = brcm_nvram_of_match_table,
 156         },
 157 };
 158
 159 static int __init brcm_nvram_init(void)
 160 {
 161         return platform_driver_register(&brcm_nvram_driver);
 162 }
 163
 164 subsys_initcall_sync(brcm_nvram_init);
 165
 166 MODULE_AUTHOR("Rafał Miłecki");
 167 MODULE_LICENSE("GPL");
 168 MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);