1 // SPDX-License-Identifier: GPL-2.0
3  * exynos-rng.c - Random Number Generator driver for the Exynos
7  * Loosely based on old driver from drivers/char/hw_random/exynos-rng.c:
40 /* Five seed and output registers, each 4 bytes */
51  * Driver re-seeds itself with generated random numbers to hinder
52  * backtracking of the original seed.
54  * Time for next re-seed in ms.
89 	return readl_relaxed(rng->mem + offset);  in exynos_rng_readl()
94 	writel_relaxed(val, rng->mem + offset);  in exynos_rng_writel()
98 			       const u8 *seed, unsigned int slen)  in exynos_rng_set_seed()  argument
103 	/* Round seed length because loop iterates over full register size */  in exynos_rng_set_seed()
107 		return -EINVAL;  in exynos_rng_set_seed()
112 		val = seed[i] << 24;  in exynos_rng_set_seed()
113 		val |= seed[i + 1] << 16;  in exynos_rng_set_seed()
114 		val |= seed[i + 2] << 8;  in exynos_rng_set_seed()
115 		val |= seed[i + 3] << 0;  in exynos_rng_set_seed()
122 		dev_warn(rng->dev, "Seed setting not finished\n");  in exynos_rng_set_seed()
123 		return -EIO;  in exynos_rng_set_seed()
126 	rng->last_seeding = jiffies;  in exynos_rng_set_seed()
127 	rng->bytes_seeding = 0;  in exynos_rng_set_seed()
138  * On error: return -ERRNO.
146 	if (rng->type == EXYNOS_PRNG_EXYNOS4) {  in exynos_rng_get_random()
149 	} else if (rng->type == EXYNOS_PRNG_EXYNOS5) {  in exynos_rng_get_random()
155 			EXYNOS_RNG_STATUS) & EXYNOS_RNG_STATUS_RNG_DONE) && --retry)  in exynos_rng_get_random()
159 		return -ETIMEDOUT;  in exynos_rng_get_random()
165 	memcpy_fromio(dst, rng->mem + EXYNOS_RNG_OUT_BASE, *read);  in exynos_rng_get_random()
166 	rng->bytes_seeding += *read;  in exynos_rng_get_random()
171 /* Re-seed itself from time to time */
174 	unsigned long next_seeding = rng->last_seeding + \  in exynos_rng_reseed()
178 	u8 seed[EXYNOS_RNG_SEED_SIZE];  in exynos_rng_reseed()  local
181 	    rng->bytes_seeding < EXYNOS_RNG_RESEED_BYTES)  in exynos_rng_reseed()
184 	if (exynos_rng_get_random(rng, seed, sizeof(seed), &read))  in exynos_rng_reseed()
187 	exynos_rng_set_seed(rng, seed, read);  in exynos_rng_reseed()
190 	mutex_unlock(&rng->lock);  in exynos_rng_reseed()
191 	mutex_lock(&rng->lock);  in exynos_rng_reseed()
199 	struct exynos_rng_dev *rng = ctx->rng;  in exynos_rng_generate()
203 	ret = clk_prepare_enable(rng->clk);  in exynos_rng_generate()
207 	mutex_lock(&rng->lock);  in exynos_rng_generate()
213 		dlen -= read;  in exynos_rng_generate()
218 	mutex_unlock(&rng->lock);  in exynos_rng_generate()
220 	clk_disable_unprepare(rng->clk);  in exynos_rng_generate()
225 static int exynos_rng_seed(struct crypto_rng *tfm, const u8 *seed,  in exynos_rng_seed()  argument
229 	struct exynos_rng_dev *rng = ctx->rng;  in exynos_rng_seed()
232 	ret = clk_prepare_enable(rng->clk);  in exynos_rng_seed()
236 	mutex_lock(&rng->lock);  in exynos_rng_seed()
237 	ret = exynos_rng_set_seed(ctx->rng, seed, slen);  in exynos_rng_seed()
238 	mutex_unlock(&rng->lock);  in exynos_rng_seed()
240 	clk_disable_unprepare(rng->clk);  in exynos_rng_seed()
249 	ctx->rng = exynos_rng_dev;  in exynos_rng_kcapi_init()
256 	.seed			= exynos_rng_seed,
274 		return -EEXIST;  in exynos_rng_probe()
276 	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);  in exynos_rng_probe()
278 		return -ENOMEM;  in exynos_rng_probe()
280 	rng->type = (uintptr_t)of_device_get_match_data(&pdev->dev);  in exynos_rng_probe()
282 	mutex_init(&rng->lock);  in exynos_rng_probe()
284 	rng->dev = &pdev->dev;  in exynos_rng_probe()
285 	rng->clk = devm_clk_get(&pdev->dev, "secss");  in exynos_rng_probe()
286 	if (IS_ERR(rng->clk)) {  in exynos_rng_probe()
287 		dev_err(&pdev->dev, "Couldn't get clock.\n");  in exynos_rng_probe()
288 		return PTR_ERR(rng->clk);  in exynos_rng_probe()
291 	rng->mem = devm_platform_ioremap_resource(pdev, 0);  in exynos_rng_probe()
292 	if (IS_ERR(rng->mem))  in exynos_rng_probe()
293 		return PTR_ERR(rng->mem);  in exynos_rng_probe()
301 		dev_err(&pdev->dev,  in exynos_rng_probe()
324 	if (!rng->last_seeding)  in exynos_rng_suspend()
327 	rng->seed_save_len = 0;  in exynos_rng_suspend()
328 	ret = clk_prepare_enable(rng->clk);  in exynos_rng_suspend()
332 	mutex_lock(&rng->lock);  in exynos_rng_suspend()
335 	exynos_rng_get_random(rng, rng->seed_save, sizeof(rng->seed_save),  in exynos_rng_suspend()
336 			      &(rng->seed_save_len));  in exynos_rng_suspend()
338 	mutex_unlock(&rng->lock);  in exynos_rng_suspend()
340 	dev_dbg(rng->dev, "Stored %u bytes for seeding on system resume\n",  in exynos_rng_suspend()
341 		rng->seed_save_len);  in exynos_rng_suspend()
343 	clk_disable_unprepare(rng->clk);  in exynos_rng_suspend()
354 	if (!rng->last_seeding)  in exynos_rng_resume()
357 	ret = clk_prepare_enable(rng->clk);  in exynos_rng_resume()
361 	mutex_lock(&rng->lock);  in exynos_rng_resume()
363 	ret = exynos_rng_set_seed(rng, rng->seed_save, rng->seed_save_len);  in exynos_rng_resume()
365 	mutex_unlock(&rng->lock);  in exynos_rng_resume()
367 	clk_disable_unprepare(rng->clk);  in exynos_rng_resume()
377 		.compatible = "samsung,exynos4-rng",
380 		.compatible = "samsung,exynos5250-prng",
389 		.name	= "exynos-rng",