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