Add hwrng (hardware random number generator) driver

arch/arm/mach-bcm2708/include/mach/platform.h

@@ -62,6 +62,7 @@
 #define DMA_BASE		 (BCM2708_PERI_BASE + 0x7000)	/* DMA controller */
 #define ARM_BASE                 (BCM2708_PERI_BASE + 0xB000)	 /* BCM2708 ARM control block */
 #define PM_BASE			 (BCM2708_PERI_BASE + 0x100000) /* Power Management, Reset controller and Watchdog registers */
+#define RNG_BASE                 (BCM2708_PERI_BASE + 0x104000) /* Hardware RNG */
 #define GPIO_BASE                (BCM2708_PERI_BASE + 0x200000) /* GPIO */
 #define UART0_BASE               (BCM2708_PERI_BASE + 0x201000)	/* Uart 0 */
 #define MMCI0_BASE               (BCM2708_PERI_BASE + 0x202000) /* MMC interface */

drivers/char/hw_random/Kconfig

@@ -289,3 +289,14 @@ config HW_RANDOM_EXYNOS
 	  module will be called exynos-rng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_BCM2708
+	tristate "BCM2708 generic true random number generator support"
+	depends on HW_RANDOM && ARCH_BCM2708
+	---help---
+	 This driver provides the kernel-side support for the BCM2708 hardware.
+
+	 To compile this driver as a module, choose M here: the
+	 module will be called bcm2708-rng.
+
+	 If unsure, say N.

drivers/char/hw_random/Makefile

@@ -25,3 +25,4 @@ obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o
 obj-$(CONFIG_HW_RANDOM_PPC4XX) += ppc4xx-rng.o
 obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
 obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o
+obj-$(CONFIG_HW_RANDOM_BCM2708) += bcm2708-rng.o

drivers/char/hw_random/bcm2708-rng.c

@@ -0,0 +1,117 @@
+/**
+ * Copyright (c) 2010-2012 Broadcom. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/hw_random.h>
+#include <linux/printk.h>
+
+#include <asm/io.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+
+#define RNG_CTRL		(0x0)
+#define RNG_STATUS		(0x4)
+#define RNG_DATA		(0x8)
+#define RNG_FF_THRESHOLD	(0xc)
+
+/* enable rng */
+#define RNG_RBGEN               0x1
+/* double speed, less random mode */
+#define RNG_RBG2X               0x2
+
+/* the initial numbers generated are "less random" so will be discarded */
+#define RNG_WARMUP_COUNT      0x40000
+
+static int bcm2708_rng_data_read(struct hwrng *rng, u32 *buffer)
+{
+	void __iomem *rng_base = (void __iomem *)rng->priv;
+	unsigned words;
+	/* wait for a random number to be in fifo */
+        do {
+		words = __raw_readl(rng_base + RNG_STATUS)>>24;
+	}
+        while (words == 0);
+	/* read the random number */
+	*buffer = __raw_readl(rng_base + RNG_DATA);
+	return 4;
+}
+
+static struct hwrng bcm2708_rng_ops = {
+	.name		= "bcm2708",
+	.data_read	= bcm2708_rng_data_read,
+};
+
+static int __init bcm2708_rng_init(void)
+{
+	void __iomem *rng_base;
+	int err;
+
+	/* map peripheral */
+	rng_base = ioremap(RNG_BASE, 0x10);
+	pr_info("bcm2708_rng_init=%p\n", rng_base);
+	if (!rng_base) {
+		pr_err("bcm2708_rng_init failed to ioremap\n");
+		return -ENOMEM;
+	}
+	bcm2708_rng_ops.priv = (unsigned long)rng_base;
+	/* register driver */
+	err = hwrng_register(&bcm2708_rng_ops);
+	if (err) {
+		pr_err("bcm2708_rng_init hwrng_register()=%d\n", err);
+		iounmap(rng_base);
+	} else {
+		/* set warm-up count & enable */
+		__raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);
+		__raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);
+	}
+	return err;
+}
+
+static void __exit bcm2708_rng_exit(void)
+{
+	void __iomem *rng_base = (void __iomem *)bcm2708_rng_ops.priv;
+	pr_info("bcm2708_rng_exit\n");
+	/* disable rng hardware */
+	__raw_writel(0, rng_base + RNG_CTRL);
+	/* unregister driver */
+	hwrng_unregister(&bcm2708_rng_ops);
+	iounmap(rng_base);
+}
+
+module_init(bcm2708_rng_init);
+module_exit(bcm2708_rng_exit);
+
+MODULE_DESCRIPTION("BCM2708 H/W Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL and additional rights");