LXR linux/drivers/nvmem/brcm

   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
  17struct brcm_nvram {
  18        struct device *dev;
  19        void __iomem *base;
  20        struct nvmem_cell_info *cells;
  21        int ncells;
  22};
  23
  24struct 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
  32static 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
  44static 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
  82static 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
 114static 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
 148static const struct of_device_id brcm_nvram_of_match_table[] = {
 149        { .compatible = "brcm,nvram", },
 150        {},
 151};
 152
 153static 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
 161static int __init brcm_nvram_init(void)
 162{
 163        return platform_driver_register(&brcm_nvram_driver);
 164}
 165
 166subsys_initcall_sync(brcm_nvram_init);
 167
 168MODULE_AUTHOR("Rafał Miłecki");
 169MODULE_LICENSE("GPL");
 170MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);
 171