[PATCH v3] hw_random: Add Broadcom BCM2835 RNG driver
From: Lubomir Rintel
Date: Thu Mar 28 2013 - 02:19:51 EST
This adds a driver for random number generator present on Broadcom BCM2835 SoC,
used in Raspberry Pi and Roku 2 devices.
Signed-off-by: Dom Cobley <popcornmix@xxxxxxxxx>
Signed-off-by: Lubomir Rintel <lkundrak@xxxxx>
Tested-by: Stephen Warren <swarren@xxxxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Stephen Warren <swarren@xxxxxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: linux-rpi-kernel@xxxxxxxxxxxxxxxxxxx
---
Changes for v2:
- Device tree and defconfig changes split out
- Licence changed from GPLv2+BSD to GPLv2 only
- Style fixes
Changes for v3:
- Device tree binding documentation added
.../devicetree/bindings/rng/brcm,bcm2835.txt | 13 +++
drivers/char/hw_random/Kconfig | 12 ++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/bcm2835-rng.c | 113 ++++++++++++++++++++
4 files changed, 139 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm2835.txt
create mode 100644 drivers/char/hw_random/bcm2835-rng.c
diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt b/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt
new file mode 100644
index 0000000..07ccdaa
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt
@@ -0,0 +1,13 @@
+BCM2835 Random number generator
+
+Required properties:
+
+- compatible : should be "brcm,bcm2835-rng"
+- reg : Specifies base physical address and size of the registers.
+
+Example:
+
+rng {
+ compatible = "brcm,bcm2835-rng";
+ reg = <0x7e104000 0x10>;
+};
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index c5a0262..2f9dbf7 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -86,6 +86,18 @@ config HW_RANDOM_BCM63XX
If unusure, say Y.
+config HW_RANDOM_BCM2835
+ tristate "Broadcom BCM2835 Random Number Generator support"
+ depends on HW_RANDOM && ARCH_BCM2835
+ default HW_RANDOM
+ ---help---
+ This driver provides kernel-side support for the Random Number
+ Generator hardware found on the Broadcom BCM2835 SoCs.
+
+ To compile this driver as a module, choose M here: the
+ module will be called bcm2835-rng
+
+ If unsure, say Y.
config HW_RANDOM_GEODE
tristate "AMD Geode HW Random Number Generator support"
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 1fd7eec..bed467c 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -26,3 +26,4 @@ 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_TPM) += tpm-rng.o
+obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
new file mode 100644
index 0000000..eb7f147
--- /dev/null
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -0,0 +1,113 @@
+/**
+ * Copyright (c) 2010-2012 Broadcom. All rights reserved.
+ * Copyright (c) 2013 Lubomir Rintel
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License ("GPL")
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/hw_random.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+
+#define RNG_CTRL 0x0
+#define RNG_STATUS 0x4
+#define RNG_DATA 0x8
+
+/* enable rng */
+#define RNG_RBGEN 0x1
+
+/* the initial numbers generated are "less random" so will be discarded */
+#define RNG_WARMUP_COUNT 0x40000
+
+static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
+ bool wait)
+{
+ void __iomem *rng_base = (void __iomem *)rng->priv;
+
+ while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) {
+ if (!wait)
+ return 0;
+ cpu_relax();
+ }
+
+ *(u32 *)buf = __raw_readl(rng_base + RNG_DATA);
+ return sizeof(u32);
+}
+
+static struct hwrng bcm2835_rng_ops = {
+ .name = "bcm2835",
+ .read = bcm2835_rng_read,
+};
+
+static int bcm2835_rng_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ void __iomem *rng_base;
+ int err;
+
+ /* map peripheral */
+ rng_base = of_iomap(np, 0);
+ if (!rng_base) {
+ dev_err(dev, "failed to remap rng regs");
+ return -ENODEV;
+ }
+ bcm2835_rng_ops.priv = (unsigned long)rng_base;
+
+ /* register driver */
+ err = hwrng_register(&bcm2835_rng_ops);
+ if (err) {
+ dev_err(dev, "hwrng registration failed\n");
+ iounmap(rng_base);
+ } else {
+ dev_info(dev, "hwrng registered\n");
+
+ /* 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 int bcm2835_rng_remove(struct platform_device *pdev)
+{
+ void __iomem *rng_base = (void __iomem *)bcm2835_rng_ops.priv;
+
+ /* disable rng hardware */
+ __raw_writel(0, rng_base + RNG_CTRL);
+
+ /* unregister driver */
+ hwrng_unregister(&bcm2835_rng_ops);
+ iounmap(rng_base);
+
+ return 0;
+}
+
+static const struct of_device_id bcm2835_rng_of_match[] = {
+ { .compatible = "brcm,bcm2835-rng", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
+
+static struct platform_driver bcm2835_rng_driver = {
+ .driver = {
+ .name = "bcm2835-rng",
+ .owner = THIS_MODULE,
+ .of_match_table = bcm2835_rng_of_match,
+ },
+ .probe = bcm2835_rng_probe,
+ .remove = bcm2835_rng_remove,
+};
+module_platform_driver(bcm2835_rng_driver);
+
+MODULE_AUTHOR("Lubomir Rintel <lkundrak@xxxxx>");
+MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPLv2");
--
1.7.1
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