crypto: qcom-rng - Add Qcom prng driver

This ports the Qcom prng from older hw_random driver.

No change of functionality and move from hw_random to crypto
APIs is done.

Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/Kconfig

···
 	  hardware. To compile this driver as a module, choose M here. The
 	  module will be called qcrypto.
 
+config CRYPTO_DEV_QCOM_RNG
+	tristate "Qualcomm Random Number Generator Driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	select CRYPTO_RNG
+	help
+	  This driver provides support for the Random Number
+	  Generator hardware found on Qualcomm SoCs.
+
+	  To compile this driver as a module, choose M here. The
+          module will be called qcom-rng. If unsure, say N.
+
 config CRYPTO_DEV_VMX
 	bool "Support for VMX cryptographic acceleration instructions"
 	depends on PPC64 && VSX

drivers/crypto/Makefile

···
 obj-$(CONFIG_CRYPTO_DEV_PPC4XX) += amcc/
 obj-$(CONFIG_CRYPTO_DEV_QAT) += qat/
 obj-$(CONFIG_CRYPTO_DEV_QCE) += qce/
+obj-$(CONFIG_CRYPTO_DEV_QCOM_RNG) += qcom-rng.o
 obj-$(CONFIG_CRYPTO_DEV_ROCKCHIP) += rockchip/
 obj-$(CONFIG_CRYPTO_DEV_S5P) += s5p-sss.o
 obj-$(CONFIG_CRYPTO_DEV_SAHARA) += sahara.o

drivers/crypto/qcom-rng.c

···
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017-18 Linaro Limited
+//
+// Based on msm-rng.c and downstream driver
+
+#include <crypto/internal/rng.h>
+#include <linux/clk.h>
+#include <linux/crypto.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+/* Device specific register offsets */
+#define PRNG_DATA_OUT		0x0000
+#define PRNG_STATUS		0x0004
+#define PRNG_LFSR_CFG		0x0100
+#define PRNG_CONFIG		0x0104
+
+/* Device specific register masks and config values */
+#define PRNG_LFSR_CFG_MASK	0x0000ffff
+#define PRNG_LFSR_CFG_CLOCKS	0x0000dddd
+#define PRNG_CONFIG_HW_ENABLE	BIT(1)
+#define PRNG_STATUS_DATA_AVAIL	BIT(0)
+
+#define WORD_SZ			4
+
+struct qcom_rng {
+	struct mutex lock;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+struct qcom_rng_ctx {
+	struct qcom_rng *rng;
+};
+
+static struct qcom_rng *qcom_rng_dev;
+
+static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
+{
+	unsigned int currsize = 0;
+	u32 val;
+
+	/* read random data from hardware */
+	do {
+		val = readl_relaxed(rng->base + PRNG_STATUS);
+		if (!(val & PRNG_STATUS_DATA_AVAIL))
+			break;
+
+		val = readl_relaxed(rng->base + PRNG_DATA_OUT);
+		if (!val)
+			break;
+
+		if ((max - currsize) >= WORD_SZ) {
+			memcpy(data, &val, WORD_SZ);
+			data += WORD_SZ;
+			currsize += WORD_SZ;
+		} else {
+			/* copy only remaining bytes */
+			memcpy(data, &val, max - currsize);
+			break;
+		}
+	} while (currsize < max);
+
+	return currsize;
+}
+
+static int qcom_rng_generate(struct crypto_rng *tfm,
+			     const u8 *src, unsigned int slen,
+			     u8 *dstn, unsigned int dlen)
+{
+	struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm);
+	struct qcom_rng *rng = ctx->rng;
+	int ret;
+
+	ret = clk_prepare_enable(rng->clk);
+	if (ret)
+		return ret;
+
+	mutex_lock(&rng->lock);
+
+	ret = qcom_rng_read(rng, dstn, dlen);
+
+	mutex_unlock(&rng->lock);
+	clk_disable_unprepare(rng->clk);
+
+	return 0;
+}
+
+static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
+			 unsigned int slen)
+{
+	return 0;
+}
+
+static int qcom_rng_enable(struct qcom_rng *rng)
+{
+	u32 val;
+	int ret;
+
+	ret = clk_prepare_enable(rng->clk);
+	if (ret)
+		return ret;
+
+	/* Enable PRNG only if it is not already enabled */
+	val = readl_relaxed(rng->base + PRNG_CONFIG);
+	if (val & PRNG_CONFIG_HW_ENABLE)
+		goto already_enabled;
+
+	val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
+	val &= ~PRNG_LFSR_CFG_MASK;
+	val |= PRNG_LFSR_CFG_CLOCKS;
+	writel(val, rng->base + PRNG_LFSR_CFG);
+
+	val = readl_relaxed(rng->base + PRNG_CONFIG);
+	val |= PRNG_CONFIG_HW_ENABLE;
+	writel(val, rng->base + PRNG_CONFIG);
+
+already_enabled:
+	clk_disable_unprepare(rng->clk);
+
+	return 0;
+}
+
+static int qcom_rng_init(struct crypto_tfm *tfm)
+{
+	struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	ctx->rng = qcom_rng_dev;
+
+	return qcom_rng_enable(ctx->rng);
+}
+
+static struct rng_alg qcom_rng_alg = {
+	.generate	= qcom_rng_generate,
+	.seed		= qcom_rng_seed,
+	.seedsize	= 0,
+	.base		= {
+		.cra_name		= "stdrng",
+		.cra_driver_name	= "qcom-rng",
+		.cra_flags		= CRYPTO_ALG_TYPE_RNG,
+		.cra_priority		= 300,
+		.cra_ctxsize		= sizeof(struct qcom_rng_ctx),
+		.cra_module		= THIS_MODULE,
+		.cra_init		= qcom_rng_init,
+	}
+};
+
+static int qcom_rng_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct qcom_rng *rng;
+	int ret;
+
+	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
+	if (!rng)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, rng);
+	mutex_init(&rng->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rng->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rng->base))
+		return PTR_ERR(rng->base);
+
+	rng->clk = devm_clk_get(&pdev->dev, "core");
+	if (IS_ERR(rng->clk))
+		return PTR_ERR(rng->clk);
+
+	qcom_rng_dev = rng;
+	ret = crypto_register_rng(&qcom_rng_alg);
+	if (ret) {
+		dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
+		qcom_rng_dev = NULL;
+	}
+
+	return ret;
+}
+
+static int qcom_rng_remove(struct platform_device *pdev)
+{
+	crypto_unregister_rng(&qcom_rng_alg);
+
+	qcom_rng_dev = NULL;
+
+	return 0;
+}
+
+static const struct of_device_id qcom_rng_of_match[] = {
+	{ .compatible = "qcom,prng" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
+
+static struct platform_driver qcom_rng_driver = {
+	.probe = qcom_rng_probe,
+	.remove =  qcom_rng_remove,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = of_match_ptr(qcom_rng_of_match),
+	}
+};
+module_platform_driver(qcom_rng_driver);
+
+MODULE_ALIAS("platform:" KBUILD_MODNAME);
+MODULE_DESCRIPTION("Qualcomm random number generator driver");
+MODULE_LICENSE("GPL v2");