1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2019 HiSilicon Limited. */
3
4#include <linux/acpi.h>
5#include <linux/crypto.h>
6#include <linux/err.h>
7#include <linux/hw_random.h>
8#include <linux/io.h>
9#include <linux/iopoll.h>
10#include <linux/kernel.h>
11#include <linux/list.h>
12#include <linux/module.h>
13#include <linux/mutex.h>
14#include <linux/platform_device.h>
15#include <linux/random.h>
16#include <crypto/internal/rng.h>
17
18#define HISI_TRNG_REG		0x00F0
19#define HISI_TRNG_BYTES		4
20#define HISI_TRNG_QUALITY	512
21#define HISI_TRNG_VERSION	0x01B8
22#define HISI_TRNG_VER_V1	GENMASK(31, 0)
23#define SLEEP_US		10
24#define TIMEOUT_US		10000
25#define SW_DRBG_NUM_SHIFT	2
26#define SW_DRBG_KEY_BASE	0x082C
27#define SW_DRBG_SEED(n)         (SW_DRBG_KEY_BASE - ((n) << SW_DRBG_NUM_SHIFT))
28#define SW_DRBG_SEED_REGS_NUM	12
29#define SW_DRBG_SEED_SIZE	48
30#define SW_DRBG_BLOCKS		0x0830
31#define SW_DRBG_INIT		0x0834
32#define SW_DRBG_GEN		0x083c
33#define SW_DRBG_STATUS		0x0840
34#define SW_DRBG_BLOCKS_NUM	4095
35#define SW_DRBG_DATA_BASE	0x0850
36#define SW_DRBG_DATA_NUM	4
37#define SW_DRBG_DATA(n)		(SW_DRBG_DATA_BASE - ((n) << SW_DRBG_NUM_SHIFT))
38#define SW_DRBG_BYTES		16
39#define SW_DRBG_ENABLE_SHIFT	12
40#define SEED_SHIFT_24		24
41#define SEED_SHIFT_16		16
42#define SEED_SHIFT_8		8
43
44struct hisi_trng_list {
45	struct mutex lock;
46	struct list_head list;
47	bool is_init;
48};
49
50struct hisi_trng {
51	void __iomem *base;
52	struct hisi_trng_list *trng_list;
53	struct list_head list;
54	struct hwrng rng;
55	u32 ver;
56	bool is_used;
57	struct mutex mutex;
58};
59
60struct hisi_trng_ctx {
61	struct hisi_trng *trng;
62};
63
64static atomic_t trng_active_devs;
65static struct hisi_trng_list trng_devices;
66
67static void hisi_trng_set_seed(struct hisi_trng *trng, const u8 *seed)
68{
69	u32 val, seed_reg, i;
70
71	for (i = 0; i < SW_DRBG_SEED_SIZE;
72	     i += SW_DRBG_SEED_SIZE / SW_DRBG_SEED_REGS_NUM) {
73		val = seed[i] << SEED_SHIFT_24;
74		val |= seed[i + 1UL] << SEED_SHIFT_16;
75		val |= seed[i + 2UL] << SEED_SHIFT_8;
76		val |= seed[i + 3UL];
77
78		seed_reg = (i >> SW_DRBG_NUM_SHIFT) % SW_DRBG_SEED_REGS_NUM;
79		writel(val, trng->base + SW_DRBG_SEED(seed_reg));
80	}
81}
82
83static int hisi_trng_seed(struct crypto_rng *tfm, const u8 *seed,
84			  unsigned int slen)
85{
86	struct hisi_trng_ctx *ctx = crypto_rng_ctx(tfm);
87	struct hisi_trng *trng = ctx->trng;
88	u32 val = 0;
89	int ret = 0;
90
91	if (slen < SW_DRBG_SEED_SIZE) {
92		pr_err("slen(%u) is not matched with trng(%d)\n", slen,
93			SW_DRBG_SEED_SIZE);
94		return -EINVAL;
95	}
96
97	writel(0x0, trng->base + SW_DRBG_BLOCKS);
98	hisi_trng_set_seed(trng, seed);
99
100	writel(SW_DRBG_BLOCKS_NUM | (0x1 << SW_DRBG_ENABLE_SHIFT),
101	       trng->base + SW_DRBG_BLOCKS);
102	writel(0x1, trng->base + SW_DRBG_INIT);
103
104	ret = readl_relaxed_poll_timeout(trng->base + SW_DRBG_STATUS,
105					val, val & BIT(0), SLEEP_US, TIMEOUT_US);
106	if (ret)
107		pr_err("fail to init trng(%d)\n", ret);
108
109	return ret;
110}
111
112static int hisi_trng_generate(struct crypto_rng *tfm, const u8 *src,
113			      unsigned int slen, u8 *dstn, unsigned int dlen)
114{
115	struct hisi_trng_ctx *ctx = crypto_rng_ctx(tfm);
116	struct hisi_trng *trng = ctx->trng;
117	u32 data[SW_DRBG_DATA_NUM];
118	u32 currsize = 0;
119	u32 val = 0;
120	int ret;
121	u32 i;
122
123	if (dlen > SW_DRBG_BLOCKS_NUM * SW_DRBG_BYTES || dlen == 0) {
124		pr_err("dlen(%d) exceeds limit(%d)!\n", dlen,
125			SW_DRBG_BLOCKS_NUM * SW_DRBG_BYTES);
126		return -EINVAL;
127	}
128
129	do {
130		ret = readl_relaxed_poll_timeout(trng->base + SW_DRBG_STATUS,
131		     val, val & BIT(1), SLEEP_US, TIMEOUT_US);
132		if (ret) {
133			pr_err("fail to generate random number(%d)!\n", ret);
134			break;
135		}
136
137		for (i = 0; i < SW_DRBG_DATA_NUM; i++)
138			data[i] = readl(trng->base + SW_DRBG_DATA(i));
139
140		if (dlen - currsize >= SW_DRBG_BYTES) {
141			memcpy(dstn + currsize, data, SW_DRBG_BYTES);
142			currsize += SW_DRBG_BYTES;
143		} else {
144			memcpy(dstn + currsize, data, dlen - currsize);
145			currsize = dlen;
146		}
147
148		writel(0x1, trng->base + SW_DRBG_GEN);
149	} while (currsize < dlen);
150
151	return ret;
152}
153
154static int hisi_trng_init(struct crypto_tfm *tfm)
155{
156	struct hisi_trng_ctx *ctx = crypto_tfm_ctx(tfm);
157	struct hisi_trng *trng;
158	int ret = -EBUSY;
159
160	mutex_lock(&trng_devices.lock);
161	list_for_each_entry(trng, &trng_devices.list, list) {
162		if (!trng->is_used) {
163			trng->is_used = true;
164			ctx->trng = trng;
165			ret = 0;
166			break;
167		}
168	}
169	mutex_unlock(&trng_devices.lock);
170
171	return ret;
172}
173
174static void hisi_trng_exit(struct crypto_tfm *tfm)
175{
176	struct hisi_trng_ctx *ctx = crypto_tfm_ctx(tfm);
177
178	mutex_lock(&trng_devices.lock);
179	ctx->trng->is_used = false;
180	mutex_unlock(&trng_devices.lock);
181}
182
183static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
184{
185	struct hisi_trng *trng;
186	int currsize = 0;
187	u32 val = 0;
188	int ret;
189
190	trng = container_of(rng, struct hisi_trng, rng);
191
192	do {
193		ret = readl_poll_timeout(trng->base + HISI_TRNG_REG, val,
194					 val, SLEEP_US, TIMEOUT_US);
195		if (ret)
196			return currsize;
197
198		if (max - currsize >= HISI_TRNG_BYTES) {
199			memcpy(buf + currsize, &val, HISI_TRNG_BYTES);
200			currsize += HISI_TRNG_BYTES;
201			if (currsize == max)
202				return currsize;
203			continue;
204		}
205
206		/* copy remaining bytes */
207		memcpy(buf + currsize, &val, max - currsize);
208		currsize = max;
209	} while (currsize < max);
210
211	return currsize;
212}
213
214static struct rng_alg hisi_trng_alg = {
215	.generate = hisi_trng_generate,
216	.seed =	hisi_trng_seed,
217	.seedsize = SW_DRBG_SEED_SIZE,
218	.base = {
219		.cra_name = "stdrng",
220		.cra_driver_name = "hisi_stdrng",
221		.cra_priority = 300,
222		.cra_ctxsize = sizeof(struct hisi_trng_ctx),
223		.cra_module = THIS_MODULE,
224		.cra_init = hisi_trng_init,
225		.cra_exit = hisi_trng_exit,
226	},
227};
228
229static void hisi_trng_add_to_list(struct hisi_trng *trng)
230{
231	mutex_lock(&trng_devices.lock);
232	list_add_tail(&trng->list, &trng_devices.list);
233	mutex_unlock(&trng_devices.lock);
234}
235
236static int hisi_trng_del_from_list(struct hisi_trng *trng)
237{
238	int ret = -EBUSY;
239
240	mutex_lock(&trng_devices.lock);
241	if (!trng->is_used) {
242		list_del(&trng->list);
243		ret = 0;
244	}
245	mutex_unlock(&trng_devices.lock);
246
247	return ret;
248}
249
250static int hisi_trng_probe(struct platform_device *pdev)
251{
252	struct hisi_trng *trng;
253	int ret;
254
255	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
256	if (!trng)
257		return -ENOMEM;
258
259	platform_set_drvdata(pdev, trng);
260
261	trng->base = devm_platform_ioremap_resource(pdev, 0);
262	if (IS_ERR(trng->base))
263		return PTR_ERR(trng->base);
264
265	trng->is_used = false;
266	trng->ver = readl(trng->base + HISI_TRNG_VERSION);
267	if (!trng_devices.is_init) {
268		INIT_LIST_HEAD(&trng_devices.list);
269		mutex_init(&trng_devices.lock);
270		trng_devices.is_init = true;
271	}
272
273	hisi_trng_add_to_list(trng);
274	if (trng->ver != HISI_TRNG_VER_V1 &&
275	    atomic_inc_return(&trng_active_devs) == 1) {
276		ret = crypto_register_rng(&hisi_trng_alg);
277		if (ret) {
278			dev_err(&pdev->dev,
279				"failed to register crypto(%d)\n", ret);
280			atomic_dec_return(&trng_active_devs);
281			goto err_remove_from_list;
282		}
283	}
284
285	trng->rng.name = pdev->name;
286	trng->rng.read = hisi_trng_read;
287	trng->rng.quality = HISI_TRNG_QUALITY;
288	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
289	if (ret) {
290		dev_err(&pdev->dev, "failed to register hwrng: %d!\n", ret);
291		goto err_crypto_unregister;
292	}
293
294	return ret;
295
296err_crypto_unregister:
297	if (trng->ver != HISI_TRNG_VER_V1 &&
298	    atomic_dec_return(&trng_active_devs) == 0)
299		crypto_unregister_rng(&hisi_trng_alg);
300
301err_remove_from_list:
302	hisi_trng_del_from_list(trng);
303	return ret;
304}
305
306static void hisi_trng_remove(struct platform_device *pdev)
307{
308	struct hisi_trng *trng = platform_get_drvdata(pdev);
309
310	/* Wait until the task is finished */
311	while (hisi_trng_del_from_list(trng))
312		;
313
314	if (trng->ver != HISI_TRNG_VER_V1 &&
315	    atomic_dec_return(&trng_active_devs) == 0)
316		crypto_unregister_rng(&hisi_trng_alg);
317}
318
319static const struct acpi_device_id hisi_trng_acpi_match[] = {
320	{ "HISI02B3", 0 },
321	{ }
322};
323MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
324
325static struct platform_driver hisi_trng_driver = {
326	.probe		= hisi_trng_probe,
327	.remove_new     = hisi_trng_remove,
328	.driver		= {
329		.name	= "hisi-trng-v2",
330		.acpi_match_table = ACPI_PTR(hisi_trng_acpi_match),
331	},
332};
333
334module_platform_driver(hisi_trng_driver);
335
336MODULE_LICENSE("GPL v2");
337MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
338MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
339MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");
340