[PATCH 10/12] hw_random: add Rockchip RNG support

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

To enable proper hardening with stack protector, add support for the
Rockchip RNG. This has been tested on the RK3568.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/dts/rk356x.dtsi         |   8 +
 drivers/hw_random/Kconfig        |   7 +
 drivers/hw_random/Makefile       |   1 +
 drivers/hw_random/rockchip-rng.c | 259 +++++++++++++++++++++++++++++++
 4 files changed, 275 insertions(+)
 create mode 100644 drivers/hw_random/rockchip-rng.c

diff --git a/arch/arm/dts/rk356x.dtsi b/arch/arm/dts/rk356x.dtsi
index 195b42a8b0fb..923e18e7ccda 100644
--- a/arch/arm/dts/rk356x.dtsi
+++ b/arch/arm/dts/rk356x.dtsi
@@ -22,4 +22,12 @@ cpu_id: id@a {
 			reg = <0x0a 0x10>;
 		};
 	};
+
+	rng: rng@fe388000 {
+		compatible = "rockchip,rk3568-rng", "rockchip,cryptov2-rng";
+		reg = <0x0 0xfe388000 0x0 0x2000>;
+		clocks = <&cru CLK_TRNG_NS>, <&cru HCLK_TRNG_NS>;
+		clock-names = "trng_clk", "trng_hclk";
+		resets = <&cru SRST_TRNG_NS>;
+	};
 };
diff --git a/drivers/hw_random/Kconfig b/drivers/hw_random/Kconfig
index 8aef00d61d81..58df6a75443c 100644
--- a/drivers/hw_random/Kconfig
+++ b/drivers/hw_random/Kconfig
@@ -80,4 +80,11 @@ config HW_RANDOM_IPROC_RNG200
 	  This driver provides barebox support for the RNG200
 	  hardware found on the BCM2711.
 
+config HW_RANDOM_ROCKCHIP
+	tristate "Rockchip Random Number Generator support"
+	depends on ARCH_ROCKCHIP || COMPILE_TEST
+	help
+	  This driver provides barebox support for the Random Number
+	  Generator hardware found on Rockchip cpus.
+
 endif
diff --git a/drivers/hw_random/Makefile b/drivers/hw_random/Makefile
index 120f4c465635..8658d4e52521 100644
--- a/drivers/hw_random/Makefile
+++ b/drivers/hw_random/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o
 obj-$(CONFIG_HW_RANDOM_ATMEL) += atmel-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
 obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
+obj-$(CONFIG_HW_RANDOM_ROCKCHIP) += rockchip-rng.o
diff --git a/drivers/hw_random/rockchip-rng.c b/drivers/hw_random/rockchip-rng.c
new file mode 100644
index 000000000000..990e5fc111fd
--- /dev/null
+++ b/drivers/hw_random/rockchip-rng.c
@@ -0,0 +1,259 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rockchip-rng.c Random Number Generator driver for the Rockchip
+ *
+ * Copyright (c) 2018, Fuzhou Rockchip Electronics Co., Ltd.
+ * Author: Lin Jinhan <troy.lin@rock-chips.com>
+ *
+ */
+#include <linux/clk.h>
+#include <linux/hw_random.h>
+#include <linux/iopoll.h>
+#include <linux/reset.h>
+#include <linux/bitfield.h>
+#include <linux/mod_devicetable.h>
+#include <of.h>
+#include <of_address.h>
+#include <linux/device.h>
+
+#define HIWORD_UPDATE(val, mask, shift) \
+			((val) << (shift) | (mask) << ((shift) + 16))
+
+#define ROCKCHIP_AUTOSUSPEND_DELAY		100
+#define ROCKCHIP_POLL_PERIOD_US			100
+#define ROCKCHIP_POLL_TIMEOUT_US		10000
+#define RK_MAX_RNG_BYTE				(32)
+
+#define CRYPTO_V1_CTRL				0x0008
+#define CRYPTO_V1_RNG_START			BIT(8)
+#define CRYPTO_V1_RNG_FLUSH			BIT(9)
+#define CRYPTO_V1_TRNG_CTRL			0x0200
+#define CRYPTO_V1_OSC_ENABLE			BIT(16)
+#define CRYPTO_V1_TRNG_SAMPLE_PERIOD(x)		(x)
+#define CRYPTO_V1_TRNG_DOUT_0			0x0204
+
+#define CRYPTO_V2_RNG_CTL			0x0400
+#define CRYPTO_V2_RNG_BIT_LEN			GENMASK(5, 4)
+#define CRYPTO_V2_RNG_64_BIT_LEN		FIELD_PREP(CRYPTO_V2_RNG_BIT_LEN, 0)
+#define CRYPTO_V2_RNG_128_BIT_LEN		FIELD_PREP(CRYPTO_V2_RNG_BIT_LEN, 1)
+#define CRYPTO_V2_RNG_192_BIT_LEN		FIELD_PREP(CRYPTO_V2_RNG_BIT_LEN, 2)
+#define CRYPTO_V2_RNG_256_BIT_LEN		FIELD_PREP(CRYPTO_V2_RNG_BIT_LEN, 3)
+#define CRYPTO_V2_RNG_SOC_RING			GENMASK(3, 2)
+#define CRYPTO_V2_RNG_FASTEST_SOC_RING		FIELD_PREP(CRYPTO_V2_RNG_SOC_RING, 0)
+#define CRYPTO_V2_RNG_SLOWER_SOC_RING_0		FIELD_PREP(CRYPTO_V2_RNG_SOC_RING, 1)
+#define CRYPTO_V2_RNG_SLOWER_SOC_RING_1		FIELD_PREP(CRYPTO_V2_RNG_SOC_RING, 2)
+#define CRYPTO_V2_RNG_SLOWEST_SOC_RING		FIELD_PREP(CRYPTO_V2_RNG_SOC_RING, 3)
+#define CRYPTO_V2_RNG_ENABLE			BIT(1)
+#define CRYPTO_V2_RNG_START			BIT(0)
+#define CRYPTO_V2_RNG_SAMPLE_CNT		0x0404
+#define CRYPTO_V2_RNG_DOUT_0			0x0410
+
+struct rk_rng_soc_data {
+	const char * const *clks;
+	int clks_num;
+	int (*rk_rng_read)(struct hwrng *rng, void *buf, size_t max, bool wait);
+};
+
+struct rk_rng {
+	struct device		*dev;
+	struct hwrng		rng;
+	void __iomem		*mem;
+	struct rk_rng_soc_data	*soc_data;
+	u32			clk_num;
+	struct clk_bulk_data	*clk_bulks;
+};
+
+static void rk_rng_writel(struct rk_rng *rng, u32 val, u32 offset)
+{
+	__raw_writel(val, rng->mem + offset);
+}
+
+static u32 rk_rng_readl(struct rk_rng *rng, u32 offset)
+{
+	return __raw_readl(rng->mem + offset);
+}
+
+static int rk_rng_init(struct hwrng *rng)
+{
+	int ret;
+	struct rk_rng *rk_rng = container_of(rng, struct rk_rng, rng);
+
+	ret = clk_bulk_prepare_enable(rk_rng->clk_num, rk_rng->clk_bulks);
+	if (ret < 0) {
+		dev_err(rk_rng->dev, "failed to enable clks %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void rk_rng_cleanup(struct rk_rng *rk_rng)
+{
+	clk_bulk_disable_unprepare(rk_rng->clk_num, rk_rng->clk_bulks);
+}
+
+static void rk_rng_read_regs(struct rk_rng *rng, u32 offset, void *buf,
+			     size_t size)
+{
+	u32 i, sample;
+
+	for (i = 0; i < size; i += 4) {
+		sample = rk_rng_readl(rng, offset + i);
+		memcpy(buf + i, &sample, sizeof(sample));
+	}
+}
+
+static int rk_rng_v1_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	int ret = 0;
+	u32 reg_ctrl = 0;
+	struct rk_rng *rk_rng = container_of(rng, struct rk_rng, rng);
+
+	/* enable osc_ring to get entropy, sample period is set as 100 */
+	reg_ctrl = CRYPTO_V1_OSC_ENABLE | CRYPTO_V1_TRNG_SAMPLE_PERIOD(100);
+	rk_rng_writel(rk_rng, reg_ctrl, CRYPTO_V1_TRNG_CTRL);
+
+	reg_ctrl = HIWORD_UPDATE(CRYPTO_V1_RNG_START, CRYPTO_V1_RNG_START, 0);
+
+	rk_rng_writel(rk_rng, reg_ctrl, CRYPTO_V1_CTRL);
+
+	ret = readl_poll_timeout(rk_rng->mem + CRYPTO_V1_CTRL, reg_ctrl,
+				 !(reg_ctrl & CRYPTO_V1_RNG_START),
+				 ROCKCHIP_POLL_TIMEOUT_US);
+	if (ret < 0)
+		goto out;
+
+	ret = min_t(size_t, max, RK_MAX_RNG_BYTE);
+
+	rk_rng_read_regs(rk_rng, CRYPTO_V1_TRNG_DOUT_0, buf, ret);
+
+out:
+	/* close TRNG */
+	rk_rng_writel(rk_rng, HIWORD_UPDATE(0, CRYPTO_V1_RNG_START, 0),
+		      CRYPTO_V1_CTRL);
+
+	return ret;
+}
+
+static int rk_rng_v2_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	int ret = 0;
+	u32 reg_ctrl = 0;
+	struct rk_rng *rk_rng = container_of(rng, struct rk_rng, rng);
+
+	/* enable osc_ring to get entropy, sample period is set as 100 */
+	rk_rng_writel(rk_rng, 100, CRYPTO_V2_RNG_SAMPLE_CNT);
+
+	reg_ctrl |= CRYPTO_V2_RNG_256_BIT_LEN;
+	reg_ctrl |= CRYPTO_V2_RNG_SLOWER_SOC_RING_0;
+	reg_ctrl |= CRYPTO_V2_RNG_ENABLE;
+	reg_ctrl |= CRYPTO_V2_RNG_START;
+
+	rk_rng_writel(rk_rng, HIWORD_UPDATE(reg_ctrl, 0xffff, 0),
+			CRYPTO_V2_RNG_CTL);
+
+	ret = readl_poll_timeout(rk_rng->mem + CRYPTO_V2_RNG_CTL, reg_ctrl,
+				 !(reg_ctrl & CRYPTO_V2_RNG_START),
+				 ROCKCHIP_POLL_TIMEOUT_US);
+	if (ret < 0)
+		goto out;
+
+	ret = min_t(size_t, max, RK_MAX_RNG_BYTE);
+
+	rk_rng_read_regs(rk_rng, CRYPTO_V2_RNG_DOUT_0, buf, ret);
+
+out:
+	/* close TRNG */
+	rk_rng_writel(rk_rng, HIWORD_UPDATE(0, 0xffff, 0), CRYPTO_V2_RNG_CTL);
+
+	return ret;
+}
+
+static const struct rk_rng_soc_data rk_rng_rk3399_soc_data = {
+	.clks_num = 3,
+	.rk_rng_read = rk_rng_v1_read,
+};
+
+static const struct rk_rng_soc_data rk_rng_v1_soc_data = {
+	.clks_num = 2,
+	.rk_rng_read = rk_rng_v1_read,
+};
+
+static const struct rk_rng_soc_data rk_rng_v2_soc_data = {
+	.clks_num = 2,
+	.rk_rng_read = rk_rng_v2_read,
+};
+
+static const struct of_device_id rk_rng_dt_match[] = {
+	{
+		.compatible = "rockchip,rk3399-crypto",
+		.data = (void *)&rk_rng_rk3399_soc_data,
+	},
+	{
+		.compatible = "rockchip,cryptov1-rng",
+		.data = (void *)&rk_rng_v1_soc_data,
+	},
+	{
+		.compatible = "rockchip,cryptov2-rng",
+		.data = (void *)&rk_rng_v2_soc_data,
+	},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, rk_rng_dt_match);
+
+static int rk_rng_probe(struct device *dev)
+{
+	int ret;
+	struct rk_rng *rk_rng;
+	struct device_node *np = dev->of_node;
+	const struct of_device_id *match;
+
+	rk_rng = devm_kzalloc(dev, sizeof(struct rk_rng), GFP_KERNEL);
+	if (!rk_rng)
+		return -ENOMEM;
+
+	match = of_match_node(rk_rng_dt_match, np);
+	rk_rng->soc_data = (struct rk_rng_soc_data *)match->data;
+
+	rk_rng->dev = dev;
+	rk_rng->rng.name    = "rockchip";
+	rk_rng->rng.init    = rk_rng_init;
+	rk_rng->rng.read    = rk_rng->soc_data->rk_rng_read;
+
+	rk_rng->clk_num = clk_bulk_get_all(dev, &rk_rng->clk_bulks);
+	if (rk_rng->clk_num < rk_rng->soc_data->clks_num)
+		return dev_err_probe(dev, -EINVAL,
+				     "Missing clocks, got %d instead of %d\n",
+				     rk_rng->clk_num, rk_rng->soc_data->clks_num);
+
+	ret = device_reset_us(dev, 2);
+	if (ret)
+		return ret;
+
+	rk_rng->mem = of_iomap(dev->device_node, 0);
+	if (IS_ERR(rk_rng->mem))
+		return PTR_ERR(rk_rng->mem);
+
+	dev->priv = rk_rng;
+
+	return hwrng_register(dev, &rk_rng->rng);
+}
+
+static void rk_rng_remove(struct device *dev)
+{
+	rk_rng_cleanup(dev->priv);
+}
+
+static struct driver rk_rng_driver = {
+	.name	= "rockchip-rng",
+	.of_match_table = rk_rng_dt_match,
+	.probe	= rk_rng_probe,
+	.remove	= rk_rng_remove,
+};
+
+device_platform_driver(rk_rng_driver);
+
+MODULE_DESCRIPTION("ROCKCHIP H/W Random Number Generator driver");
+MODULE_AUTHOR("Lin Jinhan <troy.lin@rock-chips.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.39.2