1// SPDX-License-Identifier: GPL-2.0
  2// Copyright (c) 2017-18 Linaro Limited
  3//
  4// Based on msm-rng.c and downstream driver
  5
  6#include <crypto/internal/rng.h>
  7#include <linux/acpi.h>
  8#include <linux/clk.h>
  9#include <linux/crypto.h>
 10#include <linux/io.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14
 15/* Device specific register offsets */
 16#define PRNG_DATA_OUT		0x0000
 17#define PRNG_STATUS		0x0004
 18#define PRNG_LFSR_CFG		0x0100
 19#define PRNG_CONFIG		0x0104
 20
 21/* Device specific register masks and config values */
 22#define PRNG_LFSR_CFG_MASK	0x0000ffff
 23#define PRNG_LFSR_CFG_CLOCKS	0x0000dddd
 24#define PRNG_CONFIG_HW_ENABLE	BIT(1)
 25#define PRNG_STATUS_DATA_AVAIL	BIT(0)
 26
 27#define WORD_SZ			4
 28
 29struct qcom_rng {
 30	struct mutex lock;
 31	void __iomem *base;
 32	struct clk *clk;
 33	unsigned int skip_init;
 34};
 35
 36struct qcom_rng_ctx {
 37	struct qcom_rng *rng;
 38};
 39
 40static struct qcom_rng *qcom_rng_dev;
 41
 42static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
 43{
 44	unsigned int currsize = 0;
 45	u32 val;
 46
 47	/* read random data from hardware */
 48	do {
 49		val = readl_relaxed(rng->base + PRNG_STATUS);
 50		if (!(val & PRNG_STATUS_DATA_AVAIL))
 51			break;
 52
 53		val = readl_relaxed(rng->base + PRNG_DATA_OUT);
 54		if (!val)
 55			break;
 56
 57		if ((max - currsize) >= WORD_SZ) {
 58			memcpy(data, &val, WORD_SZ);
 59			data += WORD_SZ;
 60			currsize += WORD_SZ;
 61		} else {
 62			/* copy only remaining bytes */
 63			memcpy(data, &val, max - currsize);
 64			break;
 65		}
 66	} while (currsize < max);
 67
 68	return currsize;
 69}
 70
 71static int qcom_rng_generate(struct crypto_rng *tfm,
 72			     const u8 *src, unsigned int slen,
 73			     u8 *dstn, unsigned int dlen)
 74{
 75	struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm);
 76	struct qcom_rng *rng = ctx->rng;
 77	int ret;
 78
 79	ret = clk_prepare_enable(rng->clk);
 80	if (ret)
 81		return ret;
 82
 83	mutex_lock(&rng->lock);
 84
 85	ret = qcom_rng_read(rng, dstn, dlen);
 86
 87	mutex_unlock(&rng->lock);
 88	clk_disable_unprepare(rng->clk);
 89
 90	return 0;
 91}
 92
 93static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
 94			 unsigned int slen)
 95{
 96	return 0;
 97}
 98
 99static int qcom_rng_enable(struct qcom_rng *rng)
100{
101	u32 val;
102	int ret;
103
104	ret = clk_prepare_enable(rng->clk);
105	if (ret)
106		return ret;
107
108	/* Enable PRNG only if it is not already enabled */
109	val = readl_relaxed(rng->base + PRNG_CONFIG);
110	if (val & PRNG_CONFIG_HW_ENABLE)
111		goto already_enabled;
112
113	val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
114	val &= ~PRNG_LFSR_CFG_MASK;
115	val |= PRNG_LFSR_CFG_CLOCKS;
116	writel(val, rng->base + PRNG_LFSR_CFG);
117
118	val = readl_relaxed(rng->base + PRNG_CONFIG);
119	val |= PRNG_CONFIG_HW_ENABLE;
120	writel(val, rng->base + PRNG_CONFIG);
121
122already_enabled:
123	clk_disable_unprepare(rng->clk);
124
125	return 0;
126}
127
128static int qcom_rng_init(struct crypto_tfm *tfm)
129{
130	struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm);
131
132	ctx->rng = qcom_rng_dev;
133
134	if (!ctx->rng->skip_init)
135		return qcom_rng_enable(ctx->rng);
136
137	return 0;
138}
139
140static struct rng_alg qcom_rng_alg = {
141	.generate	= qcom_rng_generate,
142	.seed		= qcom_rng_seed,
143	.seedsize	= 0,
144	.base		= {
145		.cra_name		= "stdrng",
146		.cra_driver_name	= "qcom-rng",
147		.cra_flags		= CRYPTO_ALG_TYPE_RNG,
148		.cra_priority		= 300,
149		.cra_ctxsize		= sizeof(struct qcom_rng_ctx),
150		.cra_module		= THIS_MODULE,
151		.cra_init		= qcom_rng_init,
152	}
153};
154
155static int qcom_rng_probe(struct platform_device *pdev)
156{
157	struct qcom_rng *rng;
158	int ret;
159
160	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
161	if (!rng)
162		return -ENOMEM;
163
164	platform_set_drvdata(pdev, rng);
165	mutex_init(&rng->lock);
166
167	rng->base = devm_platform_ioremap_resource(pdev, 0);
168	if (IS_ERR(rng->base))
169		return PTR_ERR(rng->base);
170
171	/* ACPI systems have clk already on, so skip clk_get */
172	if (!has_acpi_companion(&pdev->dev)) {
173		rng->clk = devm_clk_get(&pdev->dev, "core");
174		if (IS_ERR(rng->clk))
175			return PTR_ERR(rng->clk);
176	}
177
178
179	rng->skip_init = (unsigned long)device_get_match_data(&pdev->dev);
180
181	qcom_rng_dev = rng;
182	ret = crypto_register_rng(&qcom_rng_alg);
183	if (ret) {
184		dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
185		qcom_rng_dev = NULL;
186	}
187
188	return ret;
189}
190
191static int qcom_rng_remove(struct platform_device *pdev)
192{
193	crypto_unregister_rng(&qcom_rng_alg);
194
195	qcom_rng_dev = NULL;
196
197	return 0;
198}
199
200#if IS_ENABLED(CONFIG_ACPI)
201static const struct acpi_device_id qcom_rng_acpi_match[] = {
202	{ .id = "QCOM8160", .driver_data = 1 },
203	{}
204};
205MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
206#endif
207
208static const struct of_device_id qcom_rng_of_match[] = {
209	{ .compatible = "qcom,prng", .data = (void *)0},
210	{ .compatible = "qcom,prng-ee", .data = (void *)1},
211	{}
212};
213MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
214
215static struct platform_driver qcom_rng_driver = {
216	.probe = qcom_rng_probe,
217	.remove =  qcom_rng_remove,
218	.driver = {
219		.name = KBUILD_MODNAME,
220		.of_match_table = of_match_ptr(qcom_rng_of_match),
221		.acpi_match_table = ACPI_PTR(qcom_rng_acpi_match),
222	}
223};
224module_platform_driver(qcom_rng_driver);
225
226MODULE_ALIAS("platform:" KBUILD_MODNAME);
227MODULE_DESCRIPTION("Qualcomm random number generator driver");
228MODULE_LICENSE("GPL v2");