1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * sl3516-ce-rng.c - hardware cryptographic offloader for SL3516 SoC.
4  *
5  * Copyright (C) 2021 Corentin Labbe <clabbe@baylibre.com>
6  *
7  * This file handle the RNG found in the SL3516 crypto engine
8  */
9 #include "sl3516-ce.h"
10 #include <linux/pm_runtime.h>
11 #include <linux/hw_random.h>
12 
13 static int sl3516_ce_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
14 {
15 	struct sl3516_ce_dev *ce;
16 	u32 *data = buf;
17 	size_t read = 0;
18 	int err;
19 
20 	ce = container_of(rng, struct sl3516_ce_dev, trng);
21 
22 #ifdef CONFIG_CRYPTO_DEV_SL3516_DEBUG
23 	ce->hwrng_stat_req++;
24 	ce->hwrng_stat_bytes += max;
25 #endif
26 
27 	err = pm_runtime_get_sync(ce->dev);
28 	if (err < 0) {
29 		pm_runtime_put_noidle(ce->dev);
30 		return err;
31 	}
32 
33 	while (read < max) {
34 		*data = readl(ce->base + IPSEC_RAND_NUM_REG);
35 		data++;
36 		read += 4;
37 	}
38 
39 	pm_runtime_put(ce->dev);
40 
41 	return read;
42 }
43 
44 int sl3516_ce_rng_register(struct sl3516_ce_dev *ce)
45 {
46 	int ret;
47 
48 	ce->trng.name = "SL3516 Crypto Engine RNG";
49 	ce->trng.read = sl3516_ce_rng_read;
50 	ce->trng.quality = 700;
51 
52 	ret = hwrng_register(&ce->trng);
53 	if (ret)
54 		dev_err(ce->dev, "Fail to register the RNG\n");
55 	return ret;
56 }
57 
58 void sl3516_ce_rng_unregister(struct sl3516_ce_dev *ce)
59 {
60 	hwrng_unregister(&ce->trng);
61 }
62