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From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
To: "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>
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Date: Tue, 26 May 2009 08:02:20 -0700
Subject: [PATCH] hwrng: Add TX4939 RNG driver
Thread-Topic: [PATCH] hwrng: Add TX4939 RNG driver
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This patch adds support for the integrated RNG of the TX4939 SoC.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
---
 drivers/char/hw_random/Kconfig      |   13 +++
 drivers/char/hw_random/Makefile     |    1 +
 drivers/char/hw_random/tx4939-rng.c |  157 +++++++++++++++++++++++++++++++=
++++
 3 files changed, 171 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/hw_random/tx4939-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfi=
g
index 5fab647..9d321cc 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -148,3 +148,16 @@ config HW_RANDOM_VIRTIO
=20
 	  To compile this driver as a module, choose M here: the
 	  module will be called virtio-rng.  If unsure, say N.
+
+config HW_RANDOM_TX4939
+	tristate "TX4939 Random Number Generator support"
+	depends on HW_RANDOM && SOC_TX4939
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on TX4939 SoC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called tx4939-rng.
+
+	  If unsure, say Y.
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makef=
ile
index e81d21a..936d388 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -15,3 +15,4 @@ obj-$(CONFIG_HW_RANDOM_IXP4XX) +=3D ixp4xx-rng.o
 obj-$(CONFIG_HW_RANDOM_OMAP) +=3D omap-rng.o
 obj-$(CONFIG_HW_RANDOM_PASEMI) +=3D pasemi-rng.o
 obj-$(CONFIG_HW_RANDOM_VIRTIO) +=3D virtio-rng.o
+obj-$(CONFIG_HW_RANDOM_TX4939) +=3D tx4939-rng.o
diff --git a/drivers/char/hw_random/tx4939-rng.c b/drivers/char/hw_random/t=
x4939-rng.c
new file mode 100644
index 0000000..27aed22
--- /dev/null
+++ b/drivers/char/hw_random/tx4939-rng.c
@@ -0,0 +1,157 @@
+/*
+ * RNG driver for TX4939 Random Number Generators (RNG)
+ *
+ * Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ *
+ * This file is subject to the terms and conditions of the GNU General Pub=
lic
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/hw_random.h>
+
+#define TX4939_RNG_RCSR		0x00000000
+#define TX4939_RNG_ROR(n)	(0x00000018 + (n) * 8)
+
+#define TX4939_RNG_RCSR_INTE	0x00000008
+#define TX4939_RNG_RCSR_RST	0x00000004
+#define TX4939_RNG_RCSR_FIN	0x00000002
+#define TX4939_RNG_RCSR_ST	0x00000001
+
+struct tx4939_rng {
+	struct hwrng rng;
+	void __iomem *base;
+	u64 databuf[3];
+	unsigned int data_avail;
+};
+
+static u64 read_rng(void __iomem *base, unsigned int offset)
+{
+	/* Caller must disable interrupts */
+	return ____raw_readq(base + offset);
+}
+
+static void write_rng(u64 val, void __iomem *base, unsigned int offset)
+{
+	return ____raw_writeq(val, base + offset);
+}
+
+static int tx4939_rng_data_present(struct hwrng *rng, int wait)
+{
+	struct tx4939_rng *rngdev =3D container_of(rng, struct tx4939_rng, rng);
+	int i;
+
+	if (rngdev->data_avail)
+		return rngdev->data_avail;
+	for (i =3D 0; i < 20; i++) {
+		local_irq_disable();
+		if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
+		      & TX4939_RNG_RCSR_ST)) {
+			rngdev->databuf[0] =3D
+				read_rng(rngdev->base, TX4939_RNG_ROR(0));
+			rngdev->databuf[1] =3D
+				read_rng(rngdev->base, TX4939_RNG_ROR(1));
+			rngdev->databuf[2] =3D
+				read_rng(rngdev->base, TX4939_RNG_ROR(2));
+			rngdev->data_avail =3D
+				sizeof(rngdev->databuf) / sizeof(u32);
+			/* Start RNG */
+			write_rng(TX4939_RNG_RCSR_ST,
+				  rngdev->base, TX4939_RNG_RCSR);
+			wait =3D 0;
+		}
+		local_irq_enable();
+		if (!wait)
+			break;
+		udelay(1);
+	}
+	return rngdev->data_avail;
+}
+
+static int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer)
+{
+	struct tx4939_rng *rngdev =3D container_of(rng, struct tx4939_rng, rng);
+
+	rngdev->data_avail--;
+	*buffer =3D *((u32 *)&rngdev->databuf + rngdev->data_avail);
+	return sizeof(u32);
+}
+
+static int __init tx4939_rng_probe(struct platform_device *dev)
+{
+	struct tx4939_rng *rngdev;
+	struct resource *r;
+	int i;
+
+	r =3D platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!r)
+		return -EBUSY;
+	rngdev =3D devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
+	if (!rngdev)
+		return -ENOMEM;
+	if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r),
+				     dev_name(&dev->dev)))
+		return -EBUSY;
+	rngdev->base =3D devm_ioremap(&dev->dev, r->start, resource_size(r));
+	if (!rngdev->base)
+		return -EBUSY;
+
+	rngdev->rng.name =3D dev_name(&dev->dev);
+	rngdev->rng.data_present =3D tx4939_rng_data_present;
+	rngdev->rng.data_read =3D tx4939_rng_data_read;
+
+	local_irq_disable();
+	/* Reset RNG */
+	write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
+	write_rng(0, rngdev->base, TX4939_RNG_RCSR);
+	/* Start RNG */
+	write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
+	local_irq_enable();
+	/* drop first two results */
+	for (i =3D 0; i < 2; i++) {
+		rngdev->data_avail =3D 0;
+		if (!tx4939_rng_data_present(&rngdev->rng, 1))
+			return -EIO;
+	}
+
+	platform_set_drvdata(dev, rngdev);
+	return hwrng_register(&rngdev->rng);
+}
+
+static int __exit tx4939_rng_remove(struct platform_device *dev)
+{
+	struct tx4939_rng *rngdev =3D platform_get_drvdata(dev);
+
+	hwrng_unregister(&rngdev->rng);
+	platform_set_drvdata(dev, NULL);
+	return 0;
+}
+
+static struct platform_driver tx4939_rng_driver =3D {
+	.driver		=3D {
+		.name	=3D "tx4939-rng",
+		.owner	=3D THIS_MODULE,
+	},
+	.remove =3D tx4939_rng_remove,
+};
+
+static int __init tx4939_rng_init(void)
+{
+	return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe);
+}
+
+static void __exit tx4939_rng_exit(void)
+{
+	platform_driver_unregister(&tx4939_rng_driver);
+}
+
+module_init(tx4939_rng_init);
+module_exit(tx4939_rng_exit);
+
+MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
+MODULE_LICENSE("GPL");
--=20
1.5.6.5


