diff options
Diffstat (limited to 'drivers/crypto/qcom-rng.c')
| -rw-r--r-- | drivers/crypto/qcom-rng.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/drivers/crypto/qcom-rng.c b/drivers/crypto/qcom-rng.c new file mode 100644 index 000000000000..e921382099d7 --- /dev/null +++ b/drivers/crypto/qcom-rng.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2017-18 Linaro Limited +// +// Based on msm-rng.c and downstream driver + +#include <crypto/internal/rng.h> +#include <linux/clk.h> +#include <linux/crypto.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> + +/* Device specific register offsets */ +#define PRNG_DATA_OUT 0x0000 +#define PRNG_STATUS 0x0004 +#define PRNG_LFSR_CFG 0x0100 +#define PRNG_CONFIG 0x0104 + +/* Device specific register masks and config values */ +#define PRNG_LFSR_CFG_MASK 0x0000ffff +#define PRNG_LFSR_CFG_CLOCKS 0x0000dddd +#define PRNG_CONFIG_HW_ENABLE BIT(1) +#define PRNG_STATUS_DATA_AVAIL BIT(0) + +#define WORD_SZ 4 + +struct qcom_rng { + struct mutex lock; + void __iomem *base; + struct clk *clk; +}; + +struct qcom_rng_ctx { + struct qcom_rng *rng; +}; + +static struct qcom_rng *qcom_rng_dev; + +static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max) +{ + unsigned int currsize = 0; + u32 val; + + /* read random data from hardware */ + do { + val = readl_relaxed(rng->base + PRNG_STATUS); + if (!(val & PRNG_STATUS_DATA_AVAIL)) + break; + + val = readl_relaxed(rng->base + PRNG_DATA_OUT); + if (!val) + break; + + if ((max - currsize) >= WORD_SZ) { + memcpy(data, &val, WORD_SZ); + data += WORD_SZ; + currsize += WORD_SZ; + } else { + /* copy only remaining bytes */ + memcpy(data, &val, max - currsize); + break; + } + } while (currsize < max); + + return currsize; +} + +static int qcom_rng_generate(struct crypto_rng *tfm, + const u8 *src, unsigned int slen, + u8 *dstn, unsigned int dlen) +{ + struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm); + struct qcom_rng *rng = ctx->rng; + int ret; + + ret = clk_prepare_enable(rng->clk); + if (ret) + return ret; + + mutex_lock(&rng->lock); + + ret = qcom_rng_read(rng, dstn, dlen); + + mutex_unlock(&rng->lock); + clk_disable_unprepare(rng->clk); + + return 0; +} + +static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed, + unsigned int slen) +{ + return 0; +} + +static int qcom_rng_enable(struct qcom_rng *rng) +{ + u32 val; + int ret; + + ret = clk_prepare_enable(rng->clk); + if (ret) + return ret; + + /* Enable PRNG only if it is not already enabled */ + val = readl_relaxed(rng->base + PRNG_CONFIG); + if (val & PRNG_CONFIG_HW_ENABLE) + goto already_enabled; + + val = readl_relaxed(rng->base + PRNG_LFSR_CFG); + val &= ~PRNG_LFSR_CFG_MASK; + val |= PRNG_LFSR_CFG_CLOCKS; + writel(val, rng->base + PRNG_LFSR_CFG); + + val = readl_relaxed(rng->base + PRNG_CONFIG); + val |= PRNG_CONFIG_HW_ENABLE; + writel(val, rng->base + PRNG_CONFIG); + +already_enabled: + clk_disable_unprepare(rng->clk); + + return 0; +} + +static int qcom_rng_init(struct crypto_tfm *tfm) +{ + struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm); + + ctx->rng = qcom_rng_dev; + + return qcom_rng_enable(ctx->rng); +} + +static struct rng_alg qcom_rng_alg = { + .generate = qcom_rng_generate, + .seed = qcom_rng_seed, + .seedsize = 0, + .base = { + .cra_name = "stdrng", + .cra_driver_name = "qcom-rng", + .cra_flags = CRYPTO_ALG_TYPE_RNG, + .cra_priority = 300, + .cra_ctxsize = sizeof(struct qcom_rng_ctx), + .cra_module = THIS_MODULE, + .cra_init = qcom_rng_init, + } +}; + +static int qcom_rng_probe(struct platform_device *pdev) +{ + struct resource *res; + struct qcom_rng *rng; + int ret; + + rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); + if (!rng) + return -ENOMEM; + + platform_set_drvdata(pdev, rng); + mutex_init(&rng->lock); + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + rng->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(rng->base)) + return PTR_ERR(rng->base); + + rng->clk = devm_clk_get(&pdev->dev, "core"); + if (IS_ERR(rng->clk)) + return PTR_ERR(rng->clk); + + qcom_rng_dev = rng; + ret = crypto_register_rng(&qcom_rng_alg); + if (ret) { + dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret); + qcom_rng_dev = NULL; + } + + return ret; +} + +static int qcom_rng_remove(struct platform_device *pdev) +{ + crypto_unregister_rng(&qcom_rng_alg); + + qcom_rng_dev = NULL; + + return 0; +} + +static const struct of_device_id qcom_rng_of_match[] = { + { .compatible = "qcom,prng" }, + {} +}; +MODULE_DEVICE_TABLE(of, qcom_rng_of_match); + +static struct platform_driver qcom_rng_driver = { + .probe = qcom_rng_probe, + .remove = qcom_rng_remove, + .driver = { + .name = KBUILD_MODNAME, + .of_match_table = of_match_ptr(qcom_rng_of_match), + } +}; +module_platform_driver(qcom_rng_driver); + +MODULE_ALIAS("platform:" KBUILD_MODNAME); +MODULE_DESCRIPTION("Qualcomm random number generator driver"); +MODULE_LICENSE("GPL v2"); |