[PATCH v4 1/7] drivers: add simple hw_random implementation
Oleksij Rempel
o.rempel at pengutronix.de
Tue Mar 21 02:24:05 PDT 2017
From: Steffen Trumtrar <s.trumtrar at pengutronix.de>
Add a simple hw_random implementation based on code from
Linux v4.5-rc5.
All the entropypool initialization stuff is left out and
the obsolete data_read/data_present calls are omitted.
Signed-off-by: Steffen Trumtrar <s.trumtrar at pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
---
drivers/Kconfig | 1 +
drivers/Makefile | 1 +
drivers/hw_random/Kconfig | 6 +++
drivers/hw_random/Makefile | 1 +
drivers/hw_random/core.c | 108 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/hw_random.h | 43 ++++++++++++++++++
6 files changed, 160 insertions(+)
create mode 100644 drivers/hw_random/Kconfig
create mode 100644 drivers/hw_random/Makefile
create mode 100644 drivers/hw_random/core.c
create mode 100644 include/linux/hw_random.h
diff --git a/drivers/Kconfig b/drivers/Kconfig
index cc086ac2d..2f5784a4d 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -21,6 +21,7 @@ source "drivers/eeprom/Kconfig"
source "drivers/input/Kconfig"
source "drivers/watchdog/Kconfig"
source "drivers/pwm/Kconfig"
+source "drivers/hw_random/Kconfig"
source "drivers/dma/Kconfig"
source "drivers/gpio/Kconfig"
source "drivers/w1/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index 6a70f6ee1..7e9b80e59 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -20,6 +20,7 @@ obj-y += misc/
obj-y += dma/
obj-y += watchdog/
obj-y += gpio/
+obj-$(CONFIG_HWRNG) += hw_random/
obj-$(CONFIG_OFTREE) += of/
obj-$(CONFIG_W1) += w1/
obj-y += pinctrl/
diff --git a/drivers/hw_random/Kconfig b/drivers/hw_random/Kconfig
new file mode 100644
index 000000000..807fcadd3
--- /dev/null
+++ b/drivers/hw_random/Kconfig
@@ -0,0 +1,6 @@
+menuconfig HWRNG
+ bool "HWRNG Support"
+ help
+ Support for HWRNG(Hardware Random Number Generator) devices.
+
+ If unsure, say no.
diff --git a/drivers/hw_random/Makefile b/drivers/hw_random/Makefile
new file mode 100644
index 000000000..15307b100
--- /dev/null
+++ b/drivers/hw_random/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_HWRNG) += core.o
diff --git a/drivers/hw_random/core.c b/drivers/hw_random/core.c
new file mode 100644
index 000000000..2991f58c3
--- /dev/null
+++ b/drivers/hw_random/core.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2016 Pengutronix, Steffen Trumtrar <kernel at pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * derived from Linux kernel drivers/char/hw_random/core.c
+ */
+
+#include <common.h>
+#include <linux/hw_random.h>
+#include <malloc.h>
+
+static LIST_HEAD(hwrngs);
+
+#define RNG_BUFFER_SIZE 32
+
+int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait)
+{
+ return rng->read(rng, buffer, size, wait);
+}
+
+static int hwrng_init(struct hwrng *rng)
+{
+ int ret = 0;
+
+ if (rng->init)
+ ret = rng->init(rng);
+
+ if (!ret)
+ list_add_tail(&rng->list, &hwrngs);
+
+ return ret;
+}
+
+static ssize_t rng_dev_read(struct cdev *cdev, void *buf, size_t size,
+ loff_t offset, unsigned long flags)
+{
+ struct hwrng *rng = container_of(cdev, struct hwrng, cdev);
+ size_t count = size;
+ ssize_t cur = 0;
+ int len;
+
+ memset(buf, 0, size);
+
+ while (count) {
+ int max = min(count, (size_t)RNG_BUFFER_SIZE);
+ len = hwrng_get_data(rng, rng->buf, max, true);
+ if (len < 0) {
+ cur = len;
+ break;
+ }
+
+ memcpy(buf + cur, rng->buf, len);
+
+ count -= len;
+ cur += len;
+ }
+
+ return cur;
+}
+
+static struct file_operations rng_chrdev_ops = {
+ .read = rng_dev_read,
+ .lseek = dev_lseek_default,
+};
+
+static int hwrng_register_cdev(struct hwrng *rng)
+{
+ rng->cdev.name = "hwrng";
+ rng->cdev.flags = DEVFS_IS_CHARACTER_DEV;
+ rng->cdev.ops = &rng_chrdev_ops;
+ rng->cdev.dev = rng->dev;
+
+ return devfs_create(&rng->cdev);
+}
+
+struct hwrng *hwrng_get_first(void)
+{
+ if (list_empty(&hwrngs))
+ return ERR_PTR(-ENODEV);
+ else
+ return list_first_entry(&hwrngs, struct hwrng, list);
+}
+
+int hwrng_register(struct device_d *dev, struct hwrng *rng)
+{
+ int err;
+
+ if (rng->name == NULL || rng->read == NULL)
+ return -EINVAL;
+
+ rng->buf = xzalloc(RNG_BUFFER_SIZE);
+ rng->dev = dev;
+
+ err = hwrng_init(rng);
+ if (err) {
+ free(rng->buf);
+ return err;
+ }
+
+ err = hwrng_register_cdev(rng);
+ if (err)
+ free(rng->buf);
+
+ return err;
+}
diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
new file mode 100644
index 000000000..299a717dd
--- /dev/null
+++ b/include/linux/hw_random.h
@@ -0,0 +1,43 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef LINUX_HWRANDOM_H_
+#define LINUX_HWRANDOM_H_
+
+#include <linux/list.h>
+
+/**
+ * struct hwrng - Hardware Random Number Generator driver
+ * @name: Unique RNG name.
+ * @init: Initialization callback (can be NULL).
+ * @read: New API. drivers can fill up to max bytes of data
+ * into the buffer. The buffer is aligned for any type.
+ * @priv: Private data, for use by the RNG driver.
+ */
+struct hwrng {
+ const char *name;
+ int (*init)(struct hwrng *rng);
+ int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
+
+ struct list_head list;
+
+ struct cdev cdev;
+ struct device_d *dev;
+ void *buf;
+};
+
+/* Register a new Hardware Random Number Generator driver. */
+int hwrng_register(struct device_d *dev, struct hwrng *rng);
+struct hwrng *hwrng_get_first(void);
+int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait);
+
+#endif /* LINUX_HWRANDOM_H_ */
--
2.11.0
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