// 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/acpi.h> #include <linux/clk.h> #include <linux/crypto.h> #include <linux/io.h> #include <linux/iopoll.h> #include <linux/kernel.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; unsigned int skip_init; }; 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; int ret; /* read random data from hardware */ do { ret = readl_poll_timeout(rng->base + PRNG_STATUS, val, val & PRNG_STATUS_DATA_AVAIL, 200, 10000); if (ret) return ret; val = readl_relaxed(rng->base + PRNG_DATA_OUT); if (!val) return -EINVAL; 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 0; } 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 ret; } 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; if (!ctx->rng->skip_init) return qcom_rng_enable(ctx->rng); return 0; } 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 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); rng->base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(rng->base)) return PTR_ERR(rng->base); /* ACPI systems have clk already on, so skip clk_get */ if (!has_acpi_companion(&pdev->dev)) { rng->clk = devm_clk_get(&pdev->dev, "core"); if (IS_ERR(rng->clk)) return PTR_ERR(rng->clk); } rng->skip_init = (unsigned long)device_get_match_data(&pdev->dev); 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 acpi_device_id __maybe_unused qcom_rng_acpi_match[] = { { .id = "QCOM8160", .driver_data = 1 }, {} }; MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match); static const struct of_device_id __maybe_unused qcom_rng_of_match[] = { { .compatible = "qcom,prng", .data = (void *)0}, { .compatible = "qcom,prng-ee", .data = (void *)1}, {} }; 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), .acpi_match_table = ACPI_PTR(qcom_rng_acpi_match), } }; module_platform_driver(qcom_rng_driver); MODULE_ALIAS("platform:" KBUILD_MODNAME); MODULE_DESCRIPTION("Qualcomm random number generator driver"); MODULE_LICENSE("GPL v2");