rng: Add StarFive JH7110 RNG driver

Adds to support JH7110 TRNG driver which is based on linux kernel's
jh7110-trng.c. This can support to generate 256-bit random numbers and
128-bit but this makes 256-bit default for convenience.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

drivers/rng/Kconfig

@@ -99,4 +99,10 @@ config TPM_RNG
 	  functionality. Enable random number generator on TPM
 	  devices.
 
+config RNG_JH7110
+	bool "StarFive JH7110 Random Number Generator support"
+	depends on DM_RNG && STARFIVE_JH7110
+	help
+	  Enable True Random Number Generator in StarFive JH7110 SoCs.
+
 endif

drivers/rng/Makefile

@@ -16,3 +16,4 @@ obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
 obj-$(CONFIG_RNG_SMCCC_TRNG) += smccc_trng.o
 obj-$(CONFIG_RNG_ARM_RNDR) += arm_rndr.o
 obj-$(CONFIG_TPM_RNG) += tpm_rng.o
+obj-$(CONFIG_RNG_JH7110) += jh7110_rng.o

drivers/rng/jh7110_rng.c

@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TRNG driver for the StarFive JH7110 SoC
+ *
+ */
+
+#include <clk.h>
+#include <dm.h>
+#include <reset.h>
+#include <rng.h>
+#include <asm/io.h>
+#include <linux/iopoll.h>
+
+/* trng register offset */
+#define STARFIVE_CTRL			0x00
+#define STARFIVE_STAT			0x04
+#define STARFIVE_MODE			0x08
+#define STARFIVE_SMODE			0x0C
+#define STARFIVE_IE			0x10
+#define STARFIVE_ISTAT			0x14
+#define STARFIVE_RAND0			0x20
+#define STARFIVE_RAND1			0x24
+#define STARFIVE_RAND2			0x28
+#define STARFIVE_RAND3			0x2C
+#define STARFIVE_RAND4			0x30
+#define STARFIVE_RAND5			0x34
+#define STARFIVE_RAND6			0x38
+#define STARFIVE_RAND7			0x3C
+#define STARFIVE_AUTO_RQSTS		0x60
+#define STARFIVE_AUTO_AGE		0x64
+
+/* CTRL CMD */
+#define STARFIVE_CTRL_EXEC_NOP		0x0
+#define STARFIVE_CTRL_GENE_RANDNUM	0x1
+#define STARFIVE_CTRL_EXEC_RANDRESEED	0x2
+
+/* STAT */
+#define STARFIVE_STAT_NONCE_MODE	BIT(2)
+#define STARFIVE_STAT_R256		BIT(3)
+#define STARFIVE_STAT_MISSION_MODE	BIT(8)
+#define STARFIVE_STAT_SEEDED		BIT(9)
+#define STARFIVE_STAT_LAST_RESEED(x)	((x) << 16)
+#define STARFIVE_STAT_SRVC_RQST		BIT(27)
+#define STARFIVE_STAT_RAND_GENERATING	BIT(30)
+#define STARFIVE_STAT_RAND_SEEDING	BIT(31)
+#define STARFIVE_STAT_RUNNING		(STARFIVE_STAT_RAND_GENERATING | \
+					 STARFIVE_STAT_RAND_SEEDING)
+
+/* MODE */
+#define STARFIVE_MODE_R256		BIT(3)
+
+/* SMODE */
+#define STARFIVE_SMODE_NONCE_MODE	BIT(2)
+#define STARFIVE_SMODE_MISSION_MODE	BIT(8)
+#define STARFIVE_SMODE_MAX_REJECTS(x)	((x) << 16)
+
+/* IE */
+#define STARFIVE_IE_RAND_RDY_EN		BIT(0)
+#define STARFIVE_IE_SEED_DONE_EN	BIT(1)
+#define STARFIVE_IE_LFSR_LOCKUP_EN	BIT(4)
+#define STARFIVE_IE_GLBL_EN		BIT(31)
+
+#define STARFIVE_IE_ALL			(STARFIVE_IE_GLBL_EN | \
+					 STARFIVE_IE_RAND_RDY_EN | \
+					 STARFIVE_IE_SEED_DONE_EN | \
+					 STARFIVE_IE_LFSR_LOCKUP_EN)
+
+/* ISTAT */
+#define STARFIVE_ISTAT_RAND_RDY		BIT(0)
+#define STARFIVE_ISTAT_SEED_DONE	BIT(1)
+#define STARFIVE_ISTAT_LFSR_LOCKUP	BIT(4)
+
+#define STARFIVE_RAND_LEN		sizeof(u32)
+
+enum mode {
+	PRNG_128BIT,
+	PRNG_256BIT,
+};
+
+struct starfive_trng_plat {
+	void *base;
+	struct clk *hclk;
+	struct clk *ahb;
+	struct reset_ctl *rst;
+	u32 mode;
+};
+
+static inline int starfive_trng_wait_idle(struct starfive_trng_plat *trng)
+{
+	u32 stat;
+
+	return readl_relaxed_poll_timeout(trng->base + STARFIVE_STAT, stat,
+					  !(stat & STARFIVE_STAT_RUNNING),
+					  100000);
+}
+
+static inline void starfive_trng_irq_mask_clear(struct starfive_trng_plat *trng)
+{
+	/* clear register: ISTAT */
+	u32 data = readl(trng->base + STARFIVE_ISTAT);
+
+	writel(data, trng->base + STARFIVE_ISTAT);
+}
+
+static int starfive_trng_cmd(struct starfive_trng_plat *trng, u32 cmd)
+{
+	u32 stat, flg;
+	int ret;
+
+	switch (cmd) {
+	case STARFIVE_CTRL_GENE_RANDNUM:
+		writel(cmd, trng->base + STARFIVE_CTRL);
+		flg = STARFIVE_ISTAT_RAND_RDY;
+		break;
+	case STARFIVE_CTRL_EXEC_RANDRESEED:
+		writel(cmd, trng->base + STARFIVE_CTRL);
+		flg = STARFIVE_ISTAT_SEED_DONE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = readl_relaxed_poll_timeout(trng->base + STARFIVE_ISTAT, stat,
+					 (stat & flg), 1000);
+	writel(flg, trng->base + STARFIVE_ISTAT);
+
+	return ret;
+}
+
+static int starfive_trng_read(struct udevice *dev, void *data, size_t len)
+{
+	struct starfive_trng_plat *trng = dev_get_plat(dev);
+	u8 *buffer = data;
+	int iter_mask;
+
+	if (trng->mode == PRNG_256BIT)
+		iter_mask = 7;
+	else
+		iter_mask = 3;
+
+	for (int i = 0; len; ++i, i &= iter_mask) {
+		u32 val;
+		size_t step;
+		int ret;
+
+		if (!i) {
+			ret = starfive_trng_cmd(trng,
+						STARFIVE_CTRL_GENE_RANDNUM);
+			if (ret)
+				return ret;
+		}
+
+		val = readl(trng->base + STARFIVE_RAND0 +
+			    (i * STARFIVE_RAND_LEN));
+		step = min_t(size_t, len, STARFIVE_RAND_LEN);
+		memcpy(buffer, &val, step);
+		buffer += step;
+		len -= step;
+	}
+
+	return 0;
+}
+
+static int starfive_trng_init(struct starfive_trng_plat *trng)
+{
+	u32 mode, intr = 0;
+
+	/* setup Auto Request/Age register */
+	writel(0, trng->base + STARFIVE_AUTO_AGE);
+	writel(0, trng->base + STARFIVE_AUTO_RQSTS);
+
+	/* clear register: ISTAT */
+	starfive_trng_irq_mask_clear(trng);
+
+	intr |= STARFIVE_IE_ALL;
+	writel(intr, trng->base + STARFIVE_IE);
+
+	mode = readl(trng->base + STARFIVE_MODE);
+
+	switch (trng->mode) {
+	case PRNG_128BIT:
+		mode &= ~STARFIVE_MODE_R256;
+		break;
+	case PRNG_256BIT:
+		mode |= STARFIVE_MODE_R256;
+		break;
+	default:
+		mode |= STARFIVE_MODE_R256;
+		break;
+	}
+
+	writel(mode, trng->base + STARFIVE_MODE);
+
+	return starfive_trng_cmd(trng, STARFIVE_CTRL_EXEC_RANDRESEED);
+}
+
+static int starfive_trng_probe(struct udevice *dev)
+{
+	struct starfive_trng_plat *pdata = dev_get_plat(dev);
+	int err;
+
+	err = clk_enable(pdata->hclk);
+	if (err)
+		return err;
+
+	err = clk_enable(pdata->ahb);
+	if (err)
+		goto err_ahb;
+
+	err = reset_deassert(pdata->rst);
+	if (err)
+		goto err_reset;
+
+	pdata->mode = PRNG_256BIT;
+
+	err = starfive_trng_init(pdata);
+	if (err)
+		goto err_trng_init;
+
+	return 0;
+
+err_trng_init:
+	reset_assert(pdata->rst);
+err_reset:
+	clk_disable(pdata->ahb);
+err_ahb:
+	clk_disable(pdata->hclk);
+
+	return err;
+}
+
+static int starfive_trng_of_to_plat(struct udevice *dev)
+{
+	struct starfive_trng_plat *pdata = dev_get_plat(dev);
+
+	pdata->base = (void *)dev_read_addr(dev);
+	if (!pdata->base)
+		return -ENODEV;
+
+	pdata->hclk = devm_clk_get(dev, "hclk");
+	if (IS_ERR(pdata->hclk))
+		return -ENODEV;
+
+	pdata->ahb = devm_clk_get(dev, "ahb");
+	if (IS_ERR(pdata->ahb))
+		return -ENODEV;
+
+	pdata->rst = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(pdata->rst))
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct dm_rng_ops starfive_trng_ops = {
+	.read = starfive_trng_read,
+};
+
+static const struct udevice_id starfive_trng_match[] = {
+	{
+		.compatible = "starfive,jh7110-trng",
+	},
+	{},
+};
+
+U_BOOT_DRIVER(starfive_trng) = {
+	.name = "jh7110-trng",
+	.id = UCLASS_RNG,
+	.of_match = starfive_trng_match,
+	.probe = starfive_trng_probe,
+	.ops = &starfive_trng_ops,
+	.plat_auto = sizeof(struct starfive_trng_plat),
+	.of_to_plat = starfive_trng_of_to_plat,
+};