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