1 files changed, 331 insertions, 0 deletions
diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c
new file mode 100644
index 0000000000..e4b385b01b
--- /dev/null
+++ b/drivers/char/hw_random/imx-rngc.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RNG driver for Freescale RNGC
+ *
+ * Copyright (C) 2008-2012 Freescale Semiconductor, Inc.
+ * Copyright (C) 2017 Martin Kaiser <martin@kaiser.cx>
+ */
+
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/hw_random.h>
+#include <linux/completion.h>
+#include <linux/io.h>
+#include <linux/bitfield.h>
+
+#define RNGC_VER_ID			0x0000
+#define RNGC_COMMAND			0x0004
+#define RNGC_CONTROL			0x0008
+#define RNGC_STATUS			0x000C
+#define RNGC_ERROR			0x0010
+#define RNGC_FIFO			0x0014
+
+/* the fields in the ver id register */
+#define RNG_TYPE			GENMASK(31, 28)
+#define RNGC_VER_MAJ_SHIFT		8
+
+/* the rng_type field */
+#define RNGC_TYPE_RNGB			0x1
+#define RNGC_TYPE_RNGC			0x2
+
+
+#define RNGC_CMD_CLR_ERR		BIT(5)
+#define RNGC_CMD_CLR_INT		BIT(4)
+#define RNGC_CMD_SEED			BIT(1)
+#define RNGC_CMD_SELF_TEST		BIT(0)
+
+#define RNGC_CTRL_MASK_ERROR		BIT(6)
+#define RNGC_CTRL_MASK_DONE		BIT(5)
+#define RNGC_CTRL_AUTO_SEED		BIT(4)
+
+#define RNGC_STATUS_ERROR		BIT(16)
+#define RNGC_STATUS_FIFO_LEVEL_MASK	GENMASK(11, 8)
+#define RNGC_STATUS_SEED_DONE		BIT(5)
+#define RNGC_STATUS_ST_DONE		BIT(4)
+
+#define RNGC_ERROR_STATUS_STAT_ERR	0x00000008
+
+#define RNGC_TIMEOUT  3000 /* 3 sec */
+
+
+static bool self_test = true;
+module_param(self_test, bool, 0);
+
+struct imx_rngc {
+	struct device		*dev;
+	struct clk		*clk;
+	void __iomem		*base;
+	struct hwrng		rng;
+	struct completion	rng_op_done;
+	/*
+	 * err_reg is written only by the irq handler and read only
+	 * when interrupts are masked, we need no spinlock
+	 */
+	u32			err_reg;
+};
+
+
+static inline void imx_rngc_irq_mask_clear(struct imx_rngc *rngc)
+{
+	u32 ctrl, cmd;
+
+	/* mask interrupts */
+	ctrl = readl(rngc->base + RNGC_CONTROL);
+	ctrl |= RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR;
+	writel(ctrl, rngc->base + RNGC_CONTROL);
+
+	/*
+	 * CLR_INT clears the interrupt only if there's no error
+	 * CLR_ERR clear the interrupt and the error register if there
+	 * is an error
+	 */
+	cmd = readl(rngc->base + RNGC_COMMAND);
+	cmd |= RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR;
+	writel(cmd, rngc->base + RNGC_COMMAND);
+}
+
+static inline void imx_rngc_irq_unmask(struct imx_rngc *rngc)
+{
+	u32 ctrl;
+
+	ctrl = readl(rngc->base + RNGC_CONTROL);
+	ctrl &= ~(RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR);
+	writel(ctrl, rngc->base + RNGC_CONTROL);
+}
+
+static int imx_rngc_self_test(struct imx_rngc *rngc)
+{
+	u32 cmd;
+	int ret;
+
+	imx_rngc_irq_unmask(rngc);
+
+	/* run self test */
+	cmd = readl(rngc->base + RNGC_COMMAND);
+	writel(cmd | RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND);
+
+	ret = wait_for_completion_timeout(&rngc->rng_op_done, msecs_to_jiffies(RNGC_TIMEOUT));
+	imx_rngc_irq_mask_clear(rngc);
+	if (!ret)
+		return -ETIMEDOUT;
+
+	return rngc->err_reg ? -EIO : 0;
+}
+
+static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
+	unsigned int status;
+	int retval = 0;
+
+	while (max >= sizeof(u32)) {
+		status = readl(rngc->base + RNGC_STATUS);
+
+		/* is there some error while reading this random number? */
+		if (status & RNGC_STATUS_ERROR)
+			break;
+
+		if (status & RNGC_STATUS_FIFO_LEVEL_MASK) {
+			/* retrieve a random number from FIFO */
+			*(u32 *)data = readl(rngc->base + RNGC_FIFO);
+
+			retval += sizeof(u32);
+			data += sizeof(u32);
+			max -= sizeof(u32);
+		}
+	}
+
+	return retval ? retval : -EIO;
+}
+
+static irqreturn_t imx_rngc_irq(int irq, void *priv)
+{
+	struct imx_rngc *rngc = (struct imx_rngc *)priv;
+	u32 status;
+
+	/*
+	 * clearing the interrupt will also clear the error register
+	 * read error and status before clearing
+	 */
+	status = readl(rngc->base + RNGC_STATUS);
+	rngc->err_reg = readl(rngc->base + RNGC_ERROR);
+
+	imx_rngc_irq_mask_clear(rngc);
+
+	if (status & (RNGC_STATUS_SEED_DONE | RNGC_STATUS_ST_DONE))
+		complete(&rngc->rng_op_done);
+
+	return IRQ_HANDLED;
+}
+
+static int imx_rngc_init(struct hwrng *rng)
+{
+	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
+	u32 cmd, ctrl;
+	int ret;
+
+	/* clear error */
+	cmd = readl(rngc->base + RNGC_COMMAND);
+	writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);
+
+	imx_rngc_irq_unmask(rngc);
+
+	/* create seed, repeat while there is some statistical error */
+	do {
+		/* seed creation */
+		cmd = readl(rngc->base + RNGC_COMMAND);
+		writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND);
+
+		ret = wait_for_completion_timeout(&rngc->rng_op_done, msecs_to_jiffies(RNGC_TIMEOUT));
+		if (!ret) {
+			ret = -ETIMEDOUT;
+			goto err;
+		}
+
+	} while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR);
+
+	if (rngc->err_reg) {
+		ret = -EIO;
+		goto err;
+	}
+
+	/*
+	 * enable automatic seeding, the rngc creates a new seed automatically
+	 * after serving 2^20 random 160-bit words
+	 */
+	ctrl = readl(rngc->base + RNGC_CONTROL);
+	ctrl |= RNGC_CTRL_AUTO_SEED;
+	writel(ctrl, rngc->base + RNGC_CONTROL);
+
+	/*
+	 * if initialisation was successful, we keep the interrupt
+	 * unmasked until imx_rngc_cleanup is called
+	 * we mask the interrupt ourselves if we return an error
+	 */
+	return 0;
+
+err:
+	imx_rngc_irq_mask_clear(rngc);
+	return ret;
+}
+
+static void imx_rngc_cleanup(struct hwrng *rng)
+{
+	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
+
+	imx_rngc_irq_mask_clear(rngc);
+}
+
+static int __init imx_rngc_probe(struct platform_device *pdev)
+{
+	struct imx_rngc *rngc;
+	int ret;
+	int irq;
+	u32 ver_id;
+	u8  rng_type;
+
+	rngc = devm_kzalloc(&pdev->dev, sizeof(*rngc), GFP_KERNEL);
+	if (!rngc)
+		return -ENOMEM;
+
+	rngc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rngc->base))
+		return PTR_ERR(rngc->base);
+
+	rngc->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+	if (IS_ERR(rngc->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(rngc->clk), "Cannot get rng_clk\n");
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ver_id = readl(rngc->base + RNGC_VER_ID);
+	rng_type = FIELD_GET(RNG_TYPE, ver_id);
+	/*
+	 * This driver supports only RNGC and RNGB. (There's a different
+	 * driver for RNGA.)
+	 */
+	if (rng_type != RNGC_TYPE_RNGC && rng_type != RNGC_TYPE_RNGB)
+		return -ENODEV;
+
+	init_completion(&rngc->rng_op_done);
+
+	rngc->rng.name = pdev->name;
+	rngc->rng.init = imx_rngc_init;
+	rngc->rng.read = imx_rngc_read;
+	rngc->rng.cleanup = imx_rngc_cleanup;
+	rngc->rng.quality = 19;
+
+	rngc->dev = &pdev->dev;
+	platform_set_drvdata(pdev, rngc);
+
+	imx_rngc_irq_mask_clear(rngc);
+
+	ret = devm_request_irq(&pdev->dev,
+			irq, imx_rngc_irq, 0, pdev->name, (void *)rngc);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "Can't get interrupt working.\n");
+
+	if (self_test) {
+		ret = imx_rngc_self_test(rngc);
+		if (ret)
+			return dev_err_probe(&pdev->dev, ret, "self test failed\n");
+	}
+
+	ret = devm_hwrng_register(&pdev->dev, &rngc->rng);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "hwrng registration failed\n");
+
+	dev_info(&pdev->dev,
+		"Freescale RNG%c registered (HW revision %d.%02d)\n",
+		rng_type == RNGC_TYPE_RNGB ? 'B' : 'C',
+		(ver_id >> RNGC_VER_MAJ_SHIFT) & 0xff, ver_id & 0xff);
+	return 0;
+}
+
+static int imx_rngc_suspend(struct device *dev)
+{
+	struct imx_rngc *rngc = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(rngc->clk);
+
+	return 0;
+}
+
+static int imx_rngc_resume(struct device *dev)
+{
+	struct imx_rngc *rngc = dev_get_drvdata(dev);
+
+	clk_prepare_enable(rngc->clk);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(imx_rngc_pm_ops, imx_rngc_suspend, imx_rngc_resume);
+
+static const struct of_device_id imx_rngc_dt_ids[] = {
+	{ .compatible = "fsl,imx25-rngb" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx_rngc_dt_ids);
+
+static struct platform_driver imx_rngc_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.pm = pm_sleep_ptr(&imx_rngc_pm_ops),
+		.of_match_table = imx_rngc_dt_ids,
+	},
+};
+
+module_platform_driver_probe(imx_rngc_driver, imx_rngc_probe);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("H/W RNGC driver for i.MX");
+MODULE_LICENSE("GPL");