drivers/nvmem/brcm_nvram.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
0004  */
0005
0006 #include <linux/io.h>
0007 #include <linux/mod_devicetable.h>
0008 #include <linux/module.h>
0009 #include <linux/nvmem-consumer.h>
0010 #include <linux/nvmem-provider.h>
0011 #include <linux/of.h>
0012 #include <linux/platform_device.h>
0013 #include <linux/slab.h>
0014
0015 #define NVRAM_MAGIC         "FLSH"
0016
0017 struct brcm_nvram {
0018     struct device *dev;
0019     void __iomem *base;
0020     struct nvmem_cell_info *cells;
0021     int ncells;
0022 };
0023
0024 struct brcm_nvram_header {
0025     char magic[4];
0026     __le32 len;
0027     __le32 crc_ver_init;    /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
0028     __le32 config_refresh;  /* 0:15 sdram_config, 16:31 sdram_refresh */
0029     __le32 config_ncdl; /* ncdl values for memc */
0030 };
0031
0032 static int brcm_nvram_read(void *context, unsigned int offset, void *val,
0033                size_t bytes)
0034 {
0035     struct brcm_nvram *priv = context;
0036     u8 *dst = val;
0037
0038     while (bytes--)
0039         *dst++ = readb(priv->base + offset++);
0040
0041     return 0;
0042 }
0043
0044 static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
0045                 size_t len)
0046 {
0047     struct device *dev = priv->dev;
0048     char *var, *value, *eq;
0049     int idx;
0050
0051     priv->ncells = 0;
0052     for (var = data + sizeof(struct brcm_nvram_header);
0053          var < (char *)data + len && *var;
0054          var += strlen(var) + 1) {
0055         priv->ncells++;
0056     }
0057
0058     priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
0059     if (!priv->cells)
0060         return -ENOMEM;
0061
0062     for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
0063          var < (char *)data + len && *var;
0064          var = value + strlen(value) + 1, idx++) {
0065         eq = strchr(var, '=');
0066         if (!eq)
0067             break;
0068         *eq = '\0';
0069         value = eq + 1;
0070
0071         priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
0072         if (!priv->cells[idx].name)
0073             return -ENOMEM;
0074         priv->cells[idx].offset = value - (char *)data;
0075         priv->cells[idx].bytes = strlen(value);
0076         priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
0077     }
0078
0079     return 0;
0080 }
0081
0082 static int brcm_nvram_parse(struct brcm_nvram *priv)
0083 {
0084     struct device *dev = priv->dev;
0085     struct brcm_nvram_header header;
0086     uint8_t *data;
0087     size_t len;
0088     int err;
0089
0090     memcpy_fromio(&header, priv->base, sizeof(header));
0091
0092     if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
0093         dev_err(dev, "Invalid NVRAM magic\n");
0094         return -EINVAL;
0095     }
0096
0097     len = le32_to_cpu(header.len);
0098
0099     data = kcalloc(1, len, GFP_KERNEL);
0100     memcpy_fromio(data, priv->base, len);
0101     data[len - 1] = '\0';
0102
0103     err = brcm_nvram_add_cells(priv, data, len);
0104     if (err) {
0105         dev_err(dev, "Failed to add cells: %d\n", err);
0106         return err;
0107     }
0108
0109     kfree(data);
0110
0111     return 0;
0112 }
0113
0114 static int brcm_nvram_probe(struct platform_device *pdev)
0115 {
0116     struct nvmem_config config = {
0117         .name = "brcm-nvram",
0118         .reg_read = brcm_nvram_read,
0119     };
0120     struct device *dev = &pdev->dev;
0121     struct resource *res;
0122     struct brcm_nvram *priv;
0123     int err;
0124
0125     priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
0126     if (!priv)
0127         return -ENOMEM;
0128     priv->dev = dev;
0129
0130     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
0131     priv->base = devm_ioremap_resource(dev, res);
0132     if (IS_ERR(priv->base))
0133         return PTR_ERR(priv->base);
0134
0135     err = brcm_nvram_parse(priv);
0136     if (err)
0137         return err;
0138
0139     config.dev = dev;
0140     config.cells = priv->cells;
0141     config.ncells = priv->ncells;
0142     config.priv = priv;
0143     config.size = resource_size(res);
0144
0145     return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
0146 }
0147
0148 static const struct of_device_id brcm_nvram_of_match_table[] = {
0149     { .compatible = "brcm,nvram", },
0150     {},
0151 };
0152
0153 static struct platform_driver brcm_nvram_driver = {
0154     .probe = brcm_nvram_probe,
0155     .driver = {
0156         .name = "brcm_nvram",
0157         .of_match_table = brcm_nvram_of_match_table,
0158     },
0159 };
0160
0161 static int __init brcm_nvram_init(void)
0162 {
0163     return platform_driver_register(&brcm_nvram_driver);
0164 }
0165
0166 subsys_initcall_sync(brcm_nvram_init);
0167
0168 MODULE_AUTHOR("Rafał Miłecki");
0169 MODULE_LICENSE("GPL");
0170 MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);