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/io.h>
   8 #include <linux/mod_devicetable.h>
   9 #include <linux/module.h>
  10 #include <linux/nvmem-consumer.h>
  11 #include <linux/nvmem-provider.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/slab.h>
  15
  16 #define NVRAM_MAGIC                     "FLSH"
  17
  18 struct brcm_nvram {
  19         struct device *dev;
  20         void __iomem *base;
  21         struct nvmem_cell_info *cells;
  22         int ncells;
  23 };
  24
  25 struct brcm_nvram_header {
  26         char magic[4];
  27         __le32 len;
  28         __le32 crc_ver_init;    /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
  29         __le32 config_refresh;  /* 0:15 sdram_config, 16:31 sdram_refresh */
  30         __le32 config_ncdl;     /* ncdl values for memc */
  31 };
  32
  33 static int brcm_nvram_read(void *context, unsigned int offset, void *val,
  34                            size_t bytes)
  35 {
  36         struct brcm_nvram *priv = context;
  37         u8 *dst = val;
  38
  39         while (bytes--)
  40                 *dst++ = readb(priv->base + offset++);
  41
  42         return 0;
  43 }
  44
  45 static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
  46                                 size_t len)
  47 {
  48         struct device *dev = priv->dev;
  49         char *var, *value, *eq;
  50         int idx;
  51
  52         priv->ncells = 0;
  53         for (var = data + sizeof(struct brcm_nvram_header);
  54              var < (char *)data + len && *var;
  55              var += strlen(var) + 1) {
  56                 priv->ncells++;
  57         }
  58
  59         priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
  60         if (!priv->cells)
  61                 return -ENOMEM;
  62
  63         for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
  64              var < (char *)data + len && *var;
  65              var = value + strlen(value) + 1, idx++) {
  66                 eq = strchr(var, '=');
  67                 if (!eq)
  68                         break;
  69                 *eq = '\0';
  70                 value = eq + 1;
  71
  72                 priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
  73                 if (!priv->cells[idx].name)
  74                         return -ENOMEM;
  75                 priv->cells[idx].offset = value - (char *)data;
  76                 priv->cells[idx].bytes = strlen(value);
  77                 priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
  78         }
  79
  80         return 0;
  81 }
  82
  83 static int brcm_nvram_parse(struct brcm_nvram *priv)
  84 {
  85         struct device *dev = priv->dev;
  86         struct brcm_nvram_header header;
  87         uint8_t *data;
  88         size_t len;
  89         int err;
  90
  91         memcpy_fromio(&header, priv->base, sizeof(header));
  92
  93         if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
  94                 dev_err(dev, "Invalid NVRAM magic\n");
  95                 return -EINVAL;
  96         }
  97
  98         len = le32_to_cpu(header.len);
  99
 100         data = kzalloc(len, GFP_KERNEL);
 101         memcpy_fromio(data, priv->base, len);
 102         data[len - 1] = '\0';
 103
 104         err = brcm_nvram_add_cells(priv, data, len);
 105         if (err) {
 106                 dev_err(dev, "Failed to add cells: %d\n", err);
 107                 return err;
 108         }
 109
 110         kfree(data);
 111
 112         return 0;
 113 }
 114
 115 static int brcm_nvram_probe(struct platform_device *pdev)
 116 {
 117         struct nvmem_config config = {
 118                 .name = "brcm-nvram",
 119                 .reg_read = brcm_nvram_read,
 120         };
 121         struct device *dev = &pdev->dev;
 122         struct resource *res;
 123         struct brcm_nvram *priv;
 124         int err;
 125
 126         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 127         if (!priv)
 128                 return -ENOMEM;
 129         priv->dev = dev;
 130
 131         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 132         priv->base = devm_ioremap_resource(dev, res);
 133         if (IS_ERR(priv->base))
 134                 return PTR_ERR(priv->base);
 135
 136         err = brcm_nvram_parse(priv);
 137         if (err)
 138                 return err;
 139
 140         bcm47xx_nvram_init_from_iomem(priv->base, resource_size(res));
 141
 142         config.dev = dev;
 143         config.cells = priv->cells;
 144         config.ncells = priv->ncells;
 145         config.priv = priv;
 146         config.size = resource_size(res);
 147
 148         return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
 149 }
 150
 151 static const struct of_device_id brcm_nvram_of_match_table[] = {
 152         { .compatible = "brcm,nvram", },
 153         {},
 154 };
 155
 156 static struct platform_driver brcm_nvram_driver = {
 157         .probe = brcm_nvram_probe,
 158         .driver = {
 159                 .name = "brcm_nvram",
 160                 .of_match_table = brcm_nvram_of_match_table,
 161         },
 162 };
 163
 164 static int __init brcm_nvram_init(void)
 165 {
 166         return platform_driver_register(&brcm_nvram_driver);
 167 }
 168
 169 subsys_initcall_sync(brcm_nvram_init);
 170
 171 MODULE_AUTHOR("Rafał Miłecki");
 172 MODULE_LICENSE("GPL");
 173 MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);