[PATCH v1 2/3] hw_random: add driver for Freescale RNGC

[Oleksij Rempel <o.rempel@pengutronix.de>]

From: Steffen Trumtrar <s.trumtrar@pengutronix.de>

The driver is ported from Freescales Linux git and can be
found in the

	vendor/freescale/imx_2.6.35_maintain

branch.

According to that code, the RNGC is found on Freescales i.MX3/5 SoCs.
The i.MX2x actually has an RNGB, which has no driver implementation
in Freescales kernel. However as it turns out, the driver for the RNGC
works fine on the (at least) i.MX25. So, they seem to be somewhat
compatible.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/hw_random/Kconfig    |  11 ++
 drivers/hw_random/Makefile   |   1 +
 drivers/hw_random/mxc-rngc.c | 305 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 317 insertions(+)
 create mode 100644 drivers/hw_random/mxc-rngc.c

diff --git a/drivers/hw_random/Kconfig b/drivers/hw_random/Kconfig
index 807fcadd3..d1297a48d 100644
--- a/drivers/hw_random/Kconfig
+++ b/drivers/hw_random/Kconfig
@@ -4,3 +4,14 @@ menuconfig HWRNG
 	  Support for HWRNG(Hardware Random Number Generator) devices.
 
 	  If unsure, say no.
+
+if HWRNG
+
+config HWRNG_MXC_RNGC
+	tristate "Freescale i.MX RNGC Random Number Generator"
+	depends on ARCH_IMX25 || ARCH_IMX35 || ARCH_IMX53
+	help
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on some Freescale i.MX processors.
+
+endif
diff --git a/drivers/hw_random/Makefile b/drivers/hw_random/Makefile
index 15307b100..79c238c48 100644
--- a/drivers/hw_random/Makefile
+++ b/drivers/hw_random/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_HWRNG)		+= core.o
+obj-$(CONFIG_HWRNG_MXC_RNGC) += mxc-rngc.o
diff --git a/drivers/hw_random/mxc-rngc.c b/drivers/hw_random/mxc-rngc.c
new file mode 100644
index 000000000..b00c0d135
--- /dev/null
+++ b/drivers/hw_random/mxc-rngc.c
@@ -0,0 +1,305 @@
+/*
+ * RNG driver for Freescale RNGC
+ *
+ * Copyright (C) 2008-2012 Freescale Semiconductor, Inc.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+/*
+ * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
+ * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
+ *
+ * derived from
+ *
+ * Hardware driver for the AMD 768 Random Number Generator (RNG)
+ * (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
+ *
+ * derived from
+ *
+ * Hardware driver for Intel i810 Random Number Generator (RNG)
+ * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
+ * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
+ *
+ * This file is licensed under  the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <common.h>
+#include <clock.h>
+#include <driver.h>
+#include <init.h>
+#include <io.h>
+#include <linux/clk.h>
+#include <linux/hw_random.h>
+
+#define RNGC_VERSION_MAJOR3 3
+
+#define RNGC_VERSION_ID				0x0000
+#define RNGC_COMMAND				0x0004
+#define RNGC_CONTROL				0x0008
+#define RNGC_STATUS				0x000C
+#define RNGC_ERROR				0x0010
+#define RNGC_FIFO				0x0014
+#define RNGC_VERIF_CTRL				0x0020
+#define RNGC_OSC_CTRL_COUNT			0x0028
+#define RNGC_OSC_COUNT				0x002C
+#define RNGC_OSC_COUNT_STATUS			0x0030
+
+#define RNGC_VERID_ZEROS_MASK			0x0f000000
+#define RNGC_VERID_RNG_TYPE_MASK		0xf0000000
+#define RNGC_VERID_RNG_TYPE_SHIFT		28
+#define RNGC_VERID_CHIP_VERSION_MASK		0x00ff0000
+#define RNGC_VERID_CHIP_VERSION_SHIFT		16
+#define RNGC_VERID_VERSION_MAJOR_MASK		0x0000ff00
+#define RNGC_VERID_VERSION_MAJOR_SHIFT		8
+#define RNGC_VERID_VERSION_MINOR_MASK		0x000000ff
+#define RNGC_VERID_VERSION_MINOR_SHIFT		0
+
+#define RNGC_CMD_ZEROS_MASK			0xffffff8c
+#define RNGC_CMD_SW_RST				0x00000040
+#define RNGC_CMD_CLR_ERR			0x00000020
+#define RNGC_CMD_CLR_INT			0x00000010
+#define RNGC_CMD_SEED				0x00000002
+#define RNGC_CMD_SELF_TEST			0x00000001
+
+#define RNGC_CTRL_ZEROS_MASK			0xfffffc8c
+#define RNGC_CTRL_CTL_ACC			0x00000200
+#define RNGC_CTRL_VERIF_MODE			0x00000100
+#define RNGC_CTRL_MASK_ERROR			0x00000040
+
+#define RNGC_CTRL_MASK_DONE			0x00000020
+#define RNGC_CTRL_AUTO_SEED			0x00000010
+#define RNGC_CTRL_FIFO_UFLOW_MASK		0x00000003
+#define RNGC_CTRL_FIFO_UFLOW_SHIFT		0
+
+#define RNGC_CTRL_FIFO_UFLOW_ZEROS_ERROR	0
+#define RNGC_CTRL_FIFO_UFLOW_ZEROS_ERROR2	1
+#define RNGC_CTRL_FIFO_UFLOW_BUS_XFR		2
+#define RNGC_CTRL_FIFO_UFLOW_ZEROS_INTR		3
+
+#define RNGC_STATUS_ST_PF_MASK			0x00c00000
+#define RNGC_STATUS_ST_PF_SHIFT			22
+#define RNGC_STATUS_ST_PF_TRNG			0x00800000
+#define RNGC_STATUS_ST_PF_PRNG			0x00400000
+#define RNGC_STATUS_ERROR			0x00010000
+#define RNGC_STATUS_FIFO_SIZE_MASK		0x0000f000
+#define RNGC_STATUS_FIFO_SIZE_SHIFT		12
+#define RNGC_STATUS_FIFO_LEVEL_MASK		0x00000f00
+#define RNGC_STATUS_FIFO_LEVEL_SHIFT		8
+#define RNGC_STATUS_NEXT_SEED_DONE		0x00000040
+#define RNGC_STATUS_SEED_DONE			0x00000020
+#define RNGC_STATUS_ST_DONE			0x00000010
+#define RNGC_STATUS_RESEED			0x00000008
+#define RNGC_STATUS_SLEEP			0x00000004
+#define RNGC_STATUS_BUSY			0x00000002
+#define RNGC_STATUS_SEC_STATE			0x00000001
+
+#define RNGC_ERROR_STATUS_ZEROS_MASK		0xffffffc0
+#define RNGC_ERROR_STATUS_BAD_KEY		0x00000040
+#define RNGC_ERROR_STATUS_RAND_ERR		0x00000020
+#define RNGC_ERROR_STATUS_FIFO_ERR		0x00000010
+#define RNGC_ERROR_STATUS_STAT_ERR		0x00000008
+#define RNGC_ERROR_STATUS_ST_ERR		0x00000004
+#define RNGC_ERROR_STATUS_OSC_ERR		0x00000002
+#define RNGC_ERROR_STATUS_LFSR_ERR		0x00000001
+
+#define RNG_ADDR_RANGE				0x34
+
+struct mxc_rngc {
+	struct device_d		*dev;
+	struct clk		*clk;
+	void __iomem		*base;
+	struct hwrng		rng;
+};
+
+static int mxc_rngc_data_present(struct hwrng *rng)
+{
+	struct mxc_rngc *rngc = container_of(rng, struct mxc_rngc, rng);
+
+	/* how many random numbers are in FIFO? [0-16] */
+	return (readl(rngc->base + RNGC_STATUS) &
+		RNGC_STATUS_FIFO_LEVEL_MASK) >> RNGC_STATUS_FIFO_LEVEL_SHIFT;
+}
+
+static int mxc_rngc_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct mxc_rngc *rngc = container_of(rng, struct mxc_rngc, rng);
+	unsigned int err;
+	int count = 0;
+	u32 *data = buf;
+
+	while (mxc_rngc_data_present(rng) && max) {
+		/* retrieve a random number from FIFO */
+		*(data+count) = readl(rngc->base + RNGC_FIFO);
+
+		/* is there some error while reading this random number? */
+		err = readl(rngc->base + RNGC_STATUS) & RNGC_STATUS_ERROR;
+		if (err)
+			break;
+
+		count += 1;
+		max -= 4;
+	}
+
+	/* if error happened doesn't return random number */
+	return err ? 0 : count * 4;
+}
+
+static int mxc_rngc_init(struct hwrng *rng)
+{
+	struct mxc_rngc *rngc = container_of(rng, struct mxc_rngc, rng);
+	unsigned int err;
+	uint64_t start;
+	u32 cmd;
+	u32 ctrl;
+	u32 osc;
+
+	err = readl(rngc->base + RNGC_STATUS) & RNGC_STATUS_ERROR;
+	if (err) {
+		/* is this a bad keys error ? */
+		if (readl(rngc->base + RNGC_ERROR) &
+		    RNGC_ERROR_STATUS_BAD_KEY) {
+			dev_err(rngc->dev, "Can't start, Bad Keys.\n");
+			return -EIO;
+		}
+	}
+
+	/* mask all interrupts, will be unmasked soon */
+	ctrl = readl(rngc->base + RNGC_CONTROL);
+	writel(ctrl | RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR,
+	       rngc->base + RNGC_CONTROL);
+
+	/* verify if oscillator is working */
+	osc = readl(rngc->base + RNGC_ERROR);
+	if (osc & RNGC_ERROR_STATUS_OSC_ERR) {
+		dev_err(rngc->dev, "RNGC Oscillator is dead!\n");
+		return -EIO;
+	}
+
+	/* do self test, repeat until get success */
+	do {
+		/* clear error */
+		cmd = readl(rngc->base + RNGC_COMMAND);
+		writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);
+
+		/* unmask all interrupt */
+		ctrl = readl(rngc->base + RNGC_CONTROL);
+		writel(ctrl & ~(RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR),
+		       rngc->base + RNGC_CONTROL);
+
+		/* run self test */
+		cmd = readl(rngc->base + RNGC_COMMAND);
+		writel(cmd | RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND);
+
+		start = get_time_ns();
+		while (!(readl(rngc->base + RNGC_STATUS) &
+			 RNGC_STATUS_ST_DONE)) {
+			if (is_timeout(start, 100 * MSECOND)) {
+				dev_err(rng->dev, "Timedout while seeding\n");
+				return -ETIMEDOUT;
+			}
+		}
+		writel(RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR,
+		       rngc->base + RNGC_COMMAND);
+	} while (readl(rngc->base + RNGC_ERROR) & RNGC_ERROR_STATUS_ST_ERR);
+
+	/* clear interrupt. Is it really necessary here? */
+	writel(RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);
+
+	start = get_time_ns();
+	/* create seed, repeat while there is some statistical error */
+	do {
+		/* clear error */
+		cmd = readl(rngc->base + RNGC_COMMAND);
+		writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);
+
+		/* seed creation */
+		cmd = readl(rngc->base + RNGC_COMMAND);
+		writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND);
+
+		while (!(readl(rngc->base + RNGC_STATUS) &
+			 RNGC_STATUS_SEED_DONE)) {
+			if (is_timeout(start, 100 * MSECOND)) {
+				dev_err(rng->dev, "Timedout while seeding\n");
+				return -ETIMEDOUT;
+			}
+		}
+		writel(RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR,
+			     rngc->base + RNGC_COMMAND);
+	} while (readl(rngc->base + RNGC_ERROR) &
+		 RNGC_ERROR_STATUS_STAT_ERR);
+
+	err = readl(rngc->base + RNGC_ERROR) &
+		(RNGC_ERROR_STATUS_STAT_ERR |
+		 RNGC_ERROR_STATUS_RAND_ERR |
+		 RNGC_ERROR_STATUS_FIFO_ERR |
+		 RNGC_ERROR_STATUS_ST_ERR |
+		 RNGC_ERROR_STATUS_OSC_ERR |
+		 RNGC_ERROR_STATUS_LFSR_ERR);
+
+	if (err) {
+		dev_err(rngc->dev, "FSL RNGC appears inoperable.\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int mxc_rngc_probe(struct device_d *dev)
+{
+	struct mxc_rngc *rngc;
+	int ret;
+
+	rngc = xzalloc(sizeof(*rngc));
+
+	rngc->base = dev_request_mem_region(dev, 0);
+	if (IS_ERR(rngc->base))
+		return PTR_ERR(rngc->base);
+
+	rngc->clk = clk_get(dev, "ipg");
+	if (IS_ERR(rngc->clk)) {
+		dev_err(dev, "Can not get rng_clk\n");
+		return PTR_ERR(rngc->clk);
+	}
+
+	ret = clk_enable(rngc->clk);
+	if (ret)
+		return ret;
+
+	rngc->rng.name = dev->name;
+	rngc->rng.read = mxc_rngc_read;
+	rngc->rng.init = mxc_rngc_init;
+
+	ret = hwrng_register(dev, &rngc->rng);
+	if (ret) {
+		dev_err(dev, "FSL RNGC registering failed (%d)\n", ret);
+		clk_disable(rngc->clk);
+
+		return ret;
+	}
+
+	dev_info(dev, "Freescale RNGC Registered.\n");
+
+	return 0;
+}
+
+static const struct of_device_id mxc_rngc_dt_ids[] = {
+	{ .compatible = "fsl,imx25-rng" },
+	{ /* sentinel */ }
+};
+
+static struct driver_d mxc_rngc_driver = {
+	.name = "mxc_rngc",
+	.probe = mxc_rngc_probe,
+	.of_compatible = mxc_rngc_dt_ids,
+};
+device_platform_driver(mxc_rngc_driver);
-- 
2.11.0


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