diff options
Diffstat (limited to 'drivers/nvmem/sunxi_sid.c')
| -rw-r--r-- | drivers/nvmem/sunxi_sid.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c new file mode 100644 index 000000000..cfa3b8506 --- /dev/null +++ b/drivers/nvmem/sunxi_sid.c @@ -0,0 +1,180 @@ +/* + * Allwinner sunXi SoCs Security ID support. + * + * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl> + * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + + +#include <linux/device.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/nvmem-provider.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> +#include <linux/slab.h> +#include <linux/random.h> + + +static struct nvmem_config econfig = { + .name = "sunxi-sid", + .read_only = true, + .owner = THIS_MODULE, +}; + +struct sunxi_sid { + void __iomem *base; +}; + +/* We read the entire key, due to a 32 bit read alignment requirement. Since we + * want to return the requested byte, this results in somewhat slower code and + * uses 4 times more reads as needed but keeps code simpler. Since the SID is + * only very rarely probed, this is not really an issue. + */ +static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid, + const unsigned int offset) +{ + u32 sid_key; + + sid_key = ioread32be(sid->base + round_down(offset, 4)); + sid_key >>= (offset % 4) * 8; + + return sid_key; /* Only return the last byte */ +} + +static int sunxi_sid_read(void *context, + const void *reg, size_t reg_size, + void *val, size_t val_size) +{ + struct sunxi_sid *sid = context; + unsigned int offset = *(u32 *)reg; + u8 *buf = val; + + while (val_size) { + *buf++ = sunxi_sid_read_byte(sid, offset); + val_size--; + offset++; + } + + return 0; +} + +static int sunxi_sid_write(void *context, const void *data, size_t count) +{ + /* Unimplemented, dummy to keep regmap core happy */ + return 0; +} + +static struct regmap_bus sunxi_sid_bus = { + .read = sunxi_sid_read, + .write = sunxi_sid_write, + .reg_format_endian_default = REGMAP_ENDIAN_NATIVE, + .val_format_endian_default = REGMAP_ENDIAN_NATIVE, +}; + +static bool sunxi_sid_writeable_reg(struct device *dev, unsigned int reg) +{ + return false; +} + +static struct regmap_config sunxi_sid_regmap_config = { + .reg_bits = 32, + .val_bits = 8, + .reg_stride = 1, + .writeable_reg = sunxi_sid_writeable_reg, +}; + +static int sunxi_sid_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct resource *res; + struct nvmem_device *nvmem; + struct regmap *regmap; + struct sunxi_sid *sid; + int ret, i, size; + char *randomness; + + sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL); + if (!sid) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + sid->base = devm_ioremap_resource(dev, res); + if (IS_ERR(sid->base)) + return PTR_ERR(sid->base); + + size = resource_size(res) - 1; + sunxi_sid_regmap_config.max_register = size; + + regmap = devm_regmap_init(dev, &sunxi_sid_bus, sid, + &sunxi_sid_regmap_config); + if (IS_ERR(regmap)) { + dev_err(dev, "regmap init failed\n"); + return PTR_ERR(regmap); + } + + econfig.dev = dev; + nvmem = nvmem_register(&econfig); + if (IS_ERR(nvmem)) + return PTR_ERR(nvmem); + + randomness = kzalloc(sizeof(u8) * size, GFP_KERNEL); + if (!randomness) { + ret = -EINVAL; + goto err_unreg_nvmem; + } + + for (i = 0; i < size; i++) + randomness[i] = sunxi_sid_read_byte(sid, i); + + add_device_randomness(randomness, size); + kfree(randomness); + + platform_set_drvdata(pdev, nvmem); + + return 0; + +err_unreg_nvmem: + nvmem_unregister(nvmem); + return ret; +} + +static int sunxi_sid_remove(struct platform_device *pdev) +{ + struct nvmem_device *nvmem = platform_get_drvdata(pdev); + + return nvmem_unregister(nvmem); +} + +static const struct of_device_id sunxi_sid_of_match[] = { + { .compatible = "allwinner,sun4i-a10-sid" }, + { .compatible = "allwinner,sun7i-a20-sid" }, + {/* sentinel */}, +}; +MODULE_DEVICE_TABLE(of, sunxi_sid_of_match); + +static struct platform_driver sunxi_sid_driver = { + .probe = sunxi_sid_probe, + .remove = sunxi_sid_remove, + .driver = { + .name = "eeprom-sunxi-sid", + .of_match_table = sunxi_sid_of_match, + }, +}; +module_platform_driver(sunxi_sid_driver); + +MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>"); +MODULE_DESCRIPTION("Allwinner sunxi security id driver"); +MODULE_LICENSE("GPL"); |