1 files changed, 345 insertions, 0 deletions
diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
new file mode 100644
index 000000000000..02e207c09e81
--- /dev/null
+++ b/drivers/char/hw_random/exynos-trng.c
@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RNG driver for Exynos TRNGs
+ *
+ * Author: Łukasz Stelmach <l.stelmach@samsung.com>
+ *
+ * Copyright 2017 (c) Samsung Electronics Software, Inc.
+ *
+ * Based on the Exynos PRNG driver drivers/crypto/exynos-rng by
+ * Krzysztof Kozłowski <krzk@kernel.org>
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/clk.h>
+#include <linux/crypto.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+
+#define EXYNOS_TRNG_CLKDIV		0x0
+
+#define EXYNOS_TRNG_CTRL		0x20
+#define EXYNOS_TRNG_CTRL_RNGEN		BIT(31)
+
+#define EXYNOS_TRNG_POST_CTRL		0x30
+#define EXYNOS_TRNG_ONLINE_CTRL		0x40
+#define EXYNOS_TRNG_ONLINE_STAT		0x44
+#define EXYNOS_TRNG_ONLINE_MAXCHI2	0x48
+#define EXYNOS_TRNG_FIFO_CTRL		0x50
+#define EXYNOS_TRNG_FIFO_0		0x80
+#define EXYNOS_TRNG_FIFO_1		0x84
+#define EXYNOS_TRNG_FIFO_2		0x88
+#define EXYNOS_TRNG_FIFO_3		0x8c
+#define EXYNOS_TRNG_FIFO_4		0x90
+#define EXYNOS_TRNG_FIFO_5		0x94
+#define EXYNOS_TRNG_FIFO_6		0x98
+#define EXYNOS_TRNG_FIFO_7		0x9c
+#define EXYNOS_TRNG_FIFO_LEN		8
+#define EXYNOS_TRNG_CLOCK_RATE		500000
+
+/* Driver feature flags */
+#define EXYNOS_SMC			BIT(0)
+
+#define EXYNOS_SMC_CALL_VAL(func_num)			\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,		\
+			   ARM_SMCCC_SMC_32,		\
+			   ARM_SMCCC_OWNER_SIP,		\
+			   func_num)
+
+/* SMC command for DTRNG access */
+#define SMC_CMD_RANDOM			EXYNOS_SMC_CALL_VAL(0x1012)
+
+/* SMC_CMD_RANDOM: arguments */
+#define HWRNG_INIT			0x0
+#define HWRNG_EXIT			0x1
+#define HWRNG_GET_DATA			0x2
+#define HWRNG_RESUME			0x3
+
+/* SMC_CMD_RANDOM: return values */
+#define HWRNG_RET_OK			0x0
+#define HWRNG_RET_RETRY_ERROR		0x2
+
+#define HWRNG_MAX_TRIES			100
+
+struct exynos_trng_dev {
+	struct device	*dev;
+	void __iomem	*mem;
+	struct clk	*clk;	/* operating clock */
+	struct clk	*pclk;	/* bus clock */
+	struct hwrng	rng;
+	unsigned long	flags;
+};
+
+static int exynos_trng_do_read_reg(struct hwrng *rng, void *data, size_t max,
+				   bool wait)
+{
+	struct exynos_trng_dev *trng = (struct exynos_trng_dev *)rng->priv;
+	int val;
+
+	max = min_t(size_t, max, (EXYNOS_TRNG_FIFO_LEN * 4));
+	writel_relaxed(max * 8, trng->mem + EXYNOS_TRNG_FIFO_CTRL);
+	val = readl_poll_timeout(trng->mem + EXYNOS_TRNG_FIFO_CTRL, val,
+				 val == 0, 200, 1000000);
+	if (val < 0)
+		return val;
+
+	memcpy_fromio(data, trng->mem + EXYNOS_TRNG_FIFO_0, max);
+
+	return max;
+}
+
+static int exynos_trng_do_read_smc(struct hwrng *rng, void *data, size_t max,
+				   bool wait)
+{
+	struct arm_smccc_res res;
+	unsigned int copied = 0;
+	u32 *buf = data;
+	int tries = 0;
+
+	while (copied < max) {
+		arm_smccc_smc(SMC_CMD_RANDOM, HWRNG_GET_DATA, 0, 0, 0, 0, 0, 0,
+			      &res);
+		switch (res.a0) {
+		case HWRNG_RET_OK:
+			*buf++ = res.a2;
+			*buf++ = res.a3;
+			copied += 8;
+			tries = 0;
+			break;
+		case HWRNG_RET_RETRY_ERROR:
+			if (!wait)
+				return copied;
+			if (++tries >= HWRNG_MAX_TRIES)
+				return copied;
+			cond_resched();
+			break;
+		default:
+			return -EIO;
+		}
+	}
+
+	return copied;
+}
+
+static int exynos_trng_init_reg(struct hwrng *rng)
+{
+	struct exynos_trng_dev *trng = (struct exynos_trng_dev *)rng->priv;
+	unsigned long sss_rate;
+	u32 val;
+
+	sss_rate = clk_get_rate(trng->clk);
+
+	/*
+	 * For most TRNG circuits the clock frequency of under 500 kHz
+	 * is safe.
+	 */
+	val = sss_rate / (EXYNOS_TRNG_CLOCK_RATE * 2);
+	if (val > 0x7fff) {
+		dev_err(trng->dev, "clock divider too large: %d\n", val);
+		return -ERANGE;
+	}
+	val = val << 1;
+	writel_relaxed(val, trng->mem + EXYNOS_TRNG_CLKDIV);
+
+	/* Enable the generator. */
+	val = EXYNOS_TRNG_CTRL_RNGEN;
+	writel_relaxed(val, trng->mem + EXYNOS_TRNG_CTRL);
+
+	/*
+	 * Disable post-processing. /dev/hwrng is supposed to deliver
+	 * unprocessed data.
+	 */
+	writel_relaxed(0, trng->mem + EXYNOS_TRNG_POST_CTRL);
+
+	return 0;
+}
+
+static int exynos_trng_init_smc(struct hwrng *rng)
+{
+	struct exynos_trng_dev *trng = (struct exynos_trng_dev *)rng->priv;
+	struct arm_smccc_res res;
+	int ret = 0;
+
+	arm_smccc_smc(SMC_CMD_RANDOM, HWRNG_INIT, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0 != HWRNG_RET_OK) {
+		dev_err(trng->dev, "SMC command for TRNG init failed (%d)\n",
+			(int)res.a0);
+		ret = -EIO;
+	}
+	if ((int)res.a0 == -1)
+		dev_info(trng->dev, "Make sure LDFW is loaded by your BL\n");
+
+	return ret;
+}
+
+static int exynos_trng_probe(struct platform_device *pdev)
+{
+	struct exynos_trng_dev *trng;
+	int ret = -ENOMEM;
+
+	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
+	if (!trng)
+		return ret;
+
+	platform_set_drvdata(pdev, trng);
+	trng->dev = &pdev->dev;
+
+	trng->flags = (unsigned long)device_get_match_data(&pdev->dev);
+
+	trng->rng.name = devm_kstrdup(&pdev->dev, dev_name(&pdev->dev),
+				      GFP_KERNEL);
+	if (!trng->rng.name)
+		return ret;
+
+	trng->rng.priv = (unsigned long)trng;
+
+	if (trng->flags & EXYNOS_SMC) {
+		trng->rng.init = exynos_trng_init_smc;
+		trng->rng.read = exynos_trng_do_read_smc;
+	} else {
+		trng->rng.init = exynos_trng_init_reg;
+		trng->rng.read = exynos_trng_do_read_reg;
+
+		trng->mem = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(trng->mem))
+			return PTR_ERR(trng->mem);
+	}
+
+	pm_runtime_enable(&pdev->dev);
+	ret = pm_runtime_resume_and_get(&pdev->dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not get runtime PM.\n");
+		goto err_pm_get;
+	}
+
+	trng->clk = devm_clk_get_enabled(&pdev->dev, "secss");
+	if (IS_ERR(trng->clk)) {
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(trng->clk),
+				    "Could not get clock\n");
+		goto err_clock;
+	}
+
+	trng->pclk = devm_clk_get_optional_enabled(&pdev->dev, "pclk");
+	if (IS_ERR(trng->pclk)) {
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(trng->pclk),
+				    "Could not get pclk\n");
+		goto err_clock;
+	}
+
+	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not register hwrng device.\n");
+		goto err_clock;
+	}
+
+	dev_info(&pdev->dev, "Exynos True Random Number Generator.\n");
+
+	return 0;
+
+err_clock:
+	pm_runtime_put_noidle(&pdev->dev);
+
+err_pm_get:
+	pm_runtime_disable(&pdev->dev);
+
+	return ret;
+}
+
+static void exynos_trng_remove(struct platform_device *pdev)
+{
+	struct exynos_trng_dev *trng = platform_get_drvdata(pdev);
+
+	if (trng->flags & EXYNOS_SMC) {
+		struct arm_smccc_res res;
+
+		arm_smccc_smc(SMC_CMD_RANDOM, HWRNG_EXIT, 0, 0, 0, 0, 0, 0,
+			      &res);
+	}
+
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+}
+
+static int exynos_trng_suspend(struct device *dev)
+{
+	struct exynos_trng_dev *trng = dev_get_drvdata(dev);
+	struct arm_smccc_res res;
+
+	if (trng->flags & EXYNOS_SMC) {
+		arm_smccc_smc(SMC_CMD_RANDOM, HWRNG_EXIT, 0, 0, 0, 0, 0, 0,
+			      &res);
+		if (res.a0 != HWRNG_RET_OK)
+			return -EIO;
+	}
+
+	pm_runtime_put_sync(dev);
+
+	return 0;
+}
+
+static int exynos_trng_resume(struct device *dev)
+{
+	struct exynos_trng_dev *trng = dev_get_drvdata(dev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0) {
+		dev_err(dev, "Could not get runtime PM.\n");
+		return ret;
+	}
+
+	if (trng->flags & EXYNOS_SMC) {
+		struct arm_smccc_res res;
+
+		arm_smccc_smc(SMC_CMD_RANDOM, HWRNG_RESUME, 0, 0, 0, 0, 0, 0,
+			      &res);
+		if (res.a0 != HWRNG_RET_OK)
+			return -EIO;
+
+		arm_smccc_smc(SMC_CMD_RANDOM, HWRNG_INIT, 0, 0, 0, 0, 0, 0,
+			      &res);
+		if (res.a0 != HWRNG_RET_OK)
+			return -EIO;
+	}
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(exynos_trng_pm_ops, exynos_trng_suspend,
+				exynos_trng_resume);
+
+static const struct of_device_id exynos_trng_dt_match[] = {
+	{
+		.compatible = "samsung,exynos5250-trng",
+	}, {
+		.compatible = "samsung,exynos850-trng",
+		.data = (void *)EXYNOS_SMC,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, exynos_trng_dt_match);
+
+static struct platform_driver exynos_trng_driver = {
+	.driver = {
+		.name = "exynos-trng",
+		.pm = pm_sleep_ptr(&exynos_trng_pm_ops),
+		.of_match_table = exynos_trng_dt_match,
+	},
+	.probe = exynos_trng_probe,
+	.remove = exynos_trng_remove,
+};
+
+module_platform_driver(exynos_trng_driver);
+
+MODULE_AUTHOR("Łukasz Stelmach");
+MODULE_DESCRIPTION("H/W TRNG driver for Exynos chips");
+MODULE_LICENSE("GPL v2");