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/iopoll.h>
 12#include <linux/kernel.h>
 13#include <linux/module.h>
 14#include <linux/of.h>
 15#include <linux/platform_device.h>
 16
 17/* Device specific register offsets */
 18#define PRNG_DATA_OUT		0x0000
 19#define PRNG_STATUS		0x0004
 20#define PRNG_LFSR_CFG		0x0100
 21#define PRNG_CONFIG		0x0104
 22
 23/* Device specific register masks and config values */
 24#define PRNG_LFSR_CFG_MASK	0x0000ffff
 25#define PRNG_LFSR_CFG_CLOCKS	0x0000dddd
 26#define PRNG_CONFIG_HW_ENABLE	BIT(1)
 27#define PRNG_STATUS_DATA_AVAIL	BIT(0)
 28
 29#define WORD_SZ			4
 30
 31struct qcom_rng {
 32	struct mutex lock;
 33	void __iomem *base;
 34	struct clk *clk;
 35	unsigned int skip_init;
 36};
 37
 38struct qcom_rng_ctx {
 39	struct qcom_rng *rng;
 40};
 41
 42static struct qcom_rng *qcom_rng_dev;
 43
 44static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
 45{
 46	unsigned int currsize = 0;
 47	u32 val;
 48	int ret;
 49
 50	/* read random data from hardware */
 51	do {
 52		ret = readl_poll_timeout(rng->base + PRNG_STATUS, val,
 53					 val & PRNG_STATUS_DATA_AVAIL,
 54					 200, 10000);
 55		if (ret)
 56			return ret;
 57
 58		val = readl_relaxed(rng->base + PRNG_DATA_OUT);
 59		if (!val)
 60			return -EINVAL;
 61
 62		if ((max - currsize) >= WORD_SZ) {
 63			memcpy(data, &val, WORD_SZ);
 64			data += WORD_SZ;
 65			currsize += WORD_SZ;
 66		} else {
 67			/* copy only remaining bytes */
 68			memcpy(data, &val, max - currsize);
 69			break;
 70		}
 71	} while (currsize < max);
 72
 73	return 0;
 74}
 75
 76static int qcom_rng_generate(struct crypto_rng *tfm,
 77			     const u8 *src, unsigned int slen,
 78			     u8 *dstn, unsigned int dlen)
 79{
 80	struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm);
 81	struct qcom_rng *rng = ctx->rng;
 82	int ret;
 83
 84	ret = clk_prepare_enable(rng->clk);
 85	if (ret)
 86		return ret;
 87
 88	mutex_lock(&rng->lock);
 89
 90	ret = qcom_rng_read(rng, dstn, dlen);
 91
 92	mutex_unlock(&rng->lock);
 93	clk_disable_unprepare(rng->clk);
 94
 95	return ret;
 96}
 97
 98static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
 99			 unsigned int slen)
100{
101	return 0;
102}
103
104static int qcom_rng_enable(struct qcom_rng *rng)
105{
106	u32 val;
107	int ret;
108
109	ret = clk_prepare_enable(rng->clk);
110	if (ret)
111		return ret;
112
113	/* Enable PRNG only if it is not already enabled */
114	val = readl_relaxed(rng->base + PRNG_CONFIG);
115	if (val & PRNG_CONFIG_HW_ENABLE)
116		goto already_enabled;
117
118	val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
119	val &= ~PRNG_LFSR_CFG_MASK;
120	val |= PRNG_LFSR_CFG_CLOCKS;
121	writel(val, rng->base + PRNG_LFSR_CFG);
122
123	val = readl_relaxed(rng->base + PRNG_CONFIG);
124	val |= PRNG_CONFIG_HW_ENABLE;
125	writel(val, rng->base + PRNG_CONFIG);
126
127already_enabled:
128	clk_disable_unprepare(rng->clk);
129
130	return 0;
131}
132
133static int qcom_rng_init(struct crypto_tfm *tfm)
134{
135	struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm);
136
137	ctx->rng = qcom_rng_dev;
138
139	if (!ctx->rng->skip_init)
140		return qcom_rng_enable(ctx->rng);
141
142	return 0;
143}
144
145static struct rng_alg qcom_rng_alg = {
146	.generate	= qcom_rng_generate,
147	.seed		= qcom_rng_seed,
148	.seedsize	= 0,
149	.base		= {
150		.cra_name		= "stdrng",
151		.cra_driver_name	= "qcom-rng",
152		.cra_flags		= CRYPTO_ALG_TYPE_RNG,
153		.cra_priority		= 300,
154		.cra_ctxsize		= sizeof(struct qcom_rng_ctx),
155		.cra_module		= THIS_MODULE,
156		.cra_init		= qcom_rng_init,
157	}
158};
159
160static int qcom_rng_probe(struct platform_device *pdev)
161{
162	struct qcom_rng *rng;
163	int ret;
164
165	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
166	if (!rng)
167		return -ENOMEM;
168
169	platform_set_drvdata(pdev, rng);
170	mutex_init(&rng->lock);
171
172	rng->base = devm_platform_ioremap_resource(pdev, 0);
173	if (IS_ERR(rng->base))
174		return PTR_ERR(rng->base);
175
176	/* ACPI systems have clk already on, so skip clk_get */
177	if (!has_acpi_companion(&pdev->dev)) {
178		rng->clk = devm_clk_get(&pdev->dev, "core");
179		if (IS_ERR(rng->clk))
180			return PTR_ERR(rng->clk);
181	}
182
183
184	rng->skip_init = (unsigned long)device_get_match_data(&pdev->dev);
185
186	qcom_rng_dev = rng;
187	ret = crypto_register_rng(&qcom_rng_alg);
188	if (ret) {
189		dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
190		qcom_rng_dev = NULL;
191	}
192
193	return ret;
194}
195
196static int qcom_rng_remove(struct platform_device *pdev)
197{
198	crypto_unregister_rng(&qcom_rng_alg);
199
200	qcom_rng_dev = NULL;
201
202	return 0;
203}
204
205static const struct acpi_device_id __maybe_unused qcom_rng_acpi_match[] = {
206	{ .id = "QCOM8160", .driver_data = 1 },
207	{}
208};
209MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
210
211static const struct of_device_id __maybe_unused qcom_rng_of_match[] = {
212	{ .compatible = "qcom,prng", .data = (void *)0},
213	{ .compatible = "qcom,prng-ee", .data = (void *)1},
214	{}
215};
216MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
217
218static struct platform_driver qcom_rng_driver = {
219	.probe = qcom_rng_probe,
220	.remove =  qcom_rng_remove,
221	.driver = {
222		.name = KBUILD_MODNAME,
223		.of_match_table = of_match_ptr(qcom_rng_of_match),
224		.acpi_match_table = ACPI_PTR(qcom_rng_acpi_match),
225	}
226};
227module_platform_driver(qcom_rng_driver);
228
229MODULE_ALIAS("platform:" KBUILD_MODNAME);
230MODULE_DESCRIPTION("Qualcomm random number generator driver");
231MODULE_LICENSE("GPL v2");