JZ4780 SoC pseudo random number generator driver using crypto framework. Adding a delay before reading RNG data and disabling RNG after reading data was suggested by Jeffery Walton.
Tested-by: Mathieu Malaterre <[email protected]> Suggested-by: Jeffrey Walton <[email protected]> Signed-off-by: PrasannaKumar Muralidharan <[email protected]> --- drivers/crypto/Kconfig | 19 +++++ drivers/crypto/Makefile | 1 + drivers/crypto/jz4780-rng.c | 173 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 193 insertions(+) create mode 100644 drivers/crypto/jz4780-rng.c diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig index 8fa7e72..8263622 100644 --- a/drivers/crypto/Kconfig +++ b/drivers/crypto/Kconfig @@ -614,6 +614,25 @@ config CRYPTO_DEV_IMGTEC_HASH hardware hash accelerator. Supporting MD5/SHA1/SHA224/SHA256 hashing algorithms. +config CRYPTO_DEV_JZ4780_RNG + tristate "JZ4780 HW pseudo random number generator support" + depends on MACH_JZ4780 || COMPILE_TEST + depends on HAS_IOMEM + select CRYPTO_RNG + select REGMAP + select SYSCON + select MFD_SYSCON + ---help--- + This driver provides kernel-side support through the + cryptographic API for the pseudo random number generator + hardware found in ingenic JZ4780 and X1000 SoC. MIPS + Creator CI20 uses JZ4780 SoC. + + To compile this driver as a module, choose M here: the + module will be called jz4780-rng. + + If unsure, say Y. + config CRYPTO_DEV_SUN4I_SS tristate "Support for Allwinner Security System cryptographic accelerator" depends on ARCH_SUNXI && !64BIT diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile index b12eb3c..3a3d970 100644 --- a/drivers/crypto/Makefile +++ b/drivers/crypto/Makefile @@ -14,6 +14,7 @@ obj-$(CONFIG_CRYPTO_DEV_GEODE) += geode-aes.o obj-$(CONFIG_CRYPTO_DEV_HIFN_795X) += hifn_795x.o obj-$(CONFIG_CRYPTO_DEV_IMGTEC_HASH) += img-hash.o obj-$(CONFIG_CRYPTO_DEV_IXP4XX) += ixp4xx_crypto.o +obj-$(CONFIG_CRYPTO_DEV_JZ4780_RNG) += jz4780-rng.o obj-$(CONFIG_CRYPTO_DEV_MV_CESA) += mv_cesa.o obj-$(CONFIG_CRYPTO_DEV_MARVELL_CESA) += marvell/ obj-$(CONFIG_CRYPTO_DEV_MEDIATEK) += mediatek/ diff --git a/drivers/crypto/jz4780-rng.c b/drivers/crypto/jz4780-rng.c new file mode 100644 index 0000000..a03f2a0 --- /dev/null +++ b/drivers/crypto/jz4780-rng.c @@ -0,0 +1,173 @@ +/* + * jz4780-rng.c - Random Number Generator driver for the jz4780 + * + * Copyright (c) 2017 PrasannaKumar Muralidharan <[email protected]> + * + * 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; + * + * 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/crypto.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/mfd/syscon.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> + +#include <crypto/internal/rng.h> + +#define REG_RNG_CTRL 0xD8 +#define REG_RNG_DATA 0xDC + +/* Context for crypto */ +struct jz4780_rng_ctx { + struct jz4780_rng *rng; +}; + +/* Device associated memory */ +struct jz4780_rng { + struct device *dev; + struct regmap *regmap; +}; + +static struct jz4780_rng *jz4780_rng; + +static int jz4780_rng_readl(struct jz4780_rng *rng, u32 offset) +{ + u32 val = 0; + int ret; + + ret = regmap_read(rng->regmap, offset, &val); + if (!ret) + return val; + + return ret; +} + +static int jz4780_rng_writel(struct jz4780_rng *rng, u32 val, u32 offset) +{ + return regmap_write(rng->regmap, offset, val); +} + +static int jz4780_rng_generate(struct crypto_rng *tfm, + const u8 *src, unsigned int slen, + u8 *dst, unsigned int dlen) +{ + struct jz4780_rng_ctx *ctx = crypto_rng_ctx(tfm); + struct jz4780_rng *rng = ctx->rng; + u32 data; + + /* + * JZ4780 Programmers manual says the RNG should not run continuously + * for more than 1s. So enable RNG, read data and disable it. + * NOTE: No issue was observed with MIPS creator CI20 board even when + * RNG ran continuously for longer periods. This is just a precaution. + * + * A delay is required so that the current RNG data is not bit shifted + * version of previous RNG data which could happen if random data is + * read continuously from this device. + */ + jz4780_rng_writel(rng, 1, REG_RNG_CTRL); + do { + data = jz4780_rng_readl(rng, REG_RNG_DATA); + memcpy((void *)dst, (void *)&data, 4); + dlen -= 4; + dst += 4; + udelay(20); + } while (dlen >= 4); + + if (dlen > 0) { + data = jz4780_rng_readl(rng, REG_RNG_DATA); + memcpy((void *)dst, (void *)&data, dlen); + } + jz4780_rng_writel(rng, 0, REG_RNG_CTRL); + + return 0; +} + +static int jz4780_rng_kcapi_init(struct crypto_tfm *tfm) +{ + struct jz4780_rng_ctx *ctx = crypto_tfm_ctx(tfm); + + ctx->rng = jz4780_rng; + + return 0; +} + +static struct rng_alg jz4780_rng_alg = { + .generate = jz4780_rng_generate, + .base = { + .cra_name = "stdrng", + .cra_driver_name = "jz4780_rng", + .cra_priority = 100, + .cra_ctxsize = sizeof(struct jz4780_rng_ctx), + .cra_module = THIS_MODULE, + .cra_init = jz4780_rng_kcapi_init, + } +}; + +static int jz4780_rng_probe(struct platform_device *pdev) +{ + struct jz4780_rng *rng; + struct resource *res; + int ret; + + rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); + if (!rng) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + rng->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node); + if (IS_ERR(rng->regmap)) + return PTR_ERR(rng->regmap); + + jz4780_rng = rng; + + ret = crypto_register_rng(&jz4780_rng_alg); + if (ret) { + dev_err(&pdev->dev, + "Couldn't register rng crypto alg: %d\n", ret); + jz4780_rng = NULL; + } + + return ret; +} + +static int jz4780_rng_remove(struct platform_device *pdev) +{ + crypto_unregister_rng(&jz4780_rng_alg); + + jz4780_rng = NULL; + + return 0; +} + +static const struct of_device_id jz4780_rng_dt_match[] = { + { + .compatible = "ingenic,jz4780-rng", + }, + { }, +}; +MODULE_DEVICE_TABLE(of, jz4780_rng_dt_match); + +static struct platform_driver jz4780_rng_driver = { + .driver = { + .name = "jz4780-rng", + .of_match_table = jz4780_rng_dt_match, + }, + .probe = jz4780_rng_probe, + .remove = jz4780_rng_remove, +}; + +module_platform_driver(jz4780_rng_driver); + +MODULE_DESCRIPTION("Ingenic JZ4780 H/W Pseudo Random Number Generator driver"); +MODULE_AUTHOR("PrasannaKumar Muralidharan <[email protected]>"); +MODULE_LICENSE("GPL"); -- 2.10.0
