diff options
Diffstat (limited to 'drivers/nvmem/sunxi_sid.c')
| -rw-r--r-- | drivers/nvmem/sunxi_sid.c | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c new file mode 100644 index 000000000..69f8e972e --- /dev/null +++ b/drivers/nvmem/sunxi_sid.c @@ -0,0 +1,258 @@ +/* + * 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/iopoll.h> +#include <linux/module.h> +#include <linux/nvmem-provider.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/random.h> + +/* Registers and special values for doing register-based SID readout on H3 */ +#define SUN8I_SID_PRCTL 0x40 +#define SUN8I_SID_RDKEY 0x60 + +#define SUN8I_SID_OFFSET_MASK 0x1FF +#define SUN8I_SID_OFFSET_SHIFT 16 +#define SUN8I_SID_OP_LOCK (0xAC << 8) +#define SUN8I_SID_READ BIT(1) + +static struct nvmem_config econfig = { + .name = "sunxi-sid", + .read_only = true, + .stride = 4, + .word_size = 1, +}; + +struct sunxi_sid_cfg { + u32 value_offset; + u32 size; + bool need_register_readout; +}; + +struct sunxi_sid { + void __iomem *base; + u32 value_offset; +}; + +/* 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, unsigned int offset, + void *val, size_t bytes) +{ + struct sunxi_sid *sid = context; + u8 *buf = val; + + /* Offset the read operation to the real position of SID */ + offset += sid->value_offset; + + while (bytes--) + *buf++ = sunxi_sid_read_byte(sid, offset++); + + return 0; +} + +static int sun8i_sid_register_readout(const struct sunxi_sid *sid, + const unsigned int offset, + u32 *out) +{ + u32 reg_val; + int ret; + + /* Set word, lock access, and set read command */ + reg_val = (offset & SUN8I_SID_OFFSET_MASK) + << SUN8I_SID_OFFSET_SHIFT; + reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ; + writel(reg_val, sid->base + SUN8I_SID_PRCTL); + + ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val, + !(reg_val & SUN8I_SID_READ), 100, 250000); + if (ret) + return ret; + + if (out) + *out = readl(sid->base + SUN8I_SID_RDKEY); + + writel(0, sid->base + SUN8I_SID_PRCTL); + + return 0; +} + +/* + * On Allwinner H3, the value on the 0x200 offset of the SID controller seems + * to be not reliable at all. + * Read by the registers instead. + */ +static int sun8i_sid_read_byte_by_reg(const struct sunxi_sid *sid, + const unsigned int offset, + u8 *out) +{ + u32 word; + int ret; + + ret = sun8i_sid_register_readout(sid, offset & ~0x03, &word); + + if (ret) + return ret; + + *out = (word >> ((offset & 0x3) * 8)) & 0xff; + + return 0; +} + +static int sun8i_sid_read_by_reg(void *context, unsigned int offset, + void *val, size_t bytes) +{ + struct sunxi_sid *sid = context; + u8 *buf = val; + int ret; + + while (bytes--) { + ret = sun8i_sid_read_byte_by_reg(sid, offset++, buf++); + if (ret) + return ret; + } + + return 0; +} + +static int sunxi_sid_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct resource *res; + struct nvmem_device *nvmem; + struct sunxi_sid *sid; + int ret, i, size; + char *randomness; + const struct sunxi_sid_cfg *cfg; + + sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL); + if (!sid) + return -ENOMEM; + + cfg = of_device_get_match_data(dev); + if (!cfg) + return -EINVAL; + sid->value_offset = cfg->value_offset; + + 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 = cfg->size; + + econfig.size = size; + econfig.dev = dev; + if (cfg->need_register_readout) + econfig.reg_read = sun8i_sid_read_by_reg; + else + econfig.reg_read = sunxi_sid_read; + econfig.priv = sid; + nvmem = nvmem_register(&econfig); + if (IS_ERR(nvmem)) + return PTR_ERR(nvmem); + + randomness = kzalloc(size, GFP_KERNEL); + if (!randomness) { + ret = -EINVAL; + goto err_unreg_nvmem; + } + + for (i = 0; i < size; i++) + econfig.reg_read(sid, i, &randomness[i], 1); + + 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 sunxi_sid_cfg sun4i_a10_cfg = { + .size = 0x10, +}; + +static const struct sunxi_sid_cfg sun7i_a20_cfg = { + .size = 0x200, +}; + +static const struct sunxi_sid_cfg sun8i_h3_cfg = { + .value_offset = 0x200, + .size = 0x100, + .need_register_readout = true, +}; + +static const struct sunxi_sid_cfg sun50i_a64_cfg = { + .value_offset = 0x200, + .size = 0x100, +}; + +static const struct of_device_id sunxi_sid_of_match[] = { + { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg }, + { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg }, + { .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg }, + { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg }, + { .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg }, + { .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg }, + {/* 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"); |