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Implementation of /dev/random using the STM32 Random Number Generator (RNG)

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5207 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2012-09-29 20:34:25 +00:00
parent b635777130
commit 36da810129
6 changed files with 359 additions and 1 deletions
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6
arch/arm/src/common/up_initialize.c
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@ -171,6 +171,12 @@ void up_initialize(void)
ramlog_consoleinit();
#endif
/* Initialize the Random Number Generator (RNG) */
#ifdef CONFIG_DEV_RANDOM
up_rnginitialize();
#endif
/* Initialize the system logging device */
#ifdef CONFIG_SYSLOG_CHAR

6
arch/arm/src/common/up_internal.h
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@ -373,6 +373,12 @@ extern void up_usbuninitialize(void);
# define up_usbuninitialize()
#endif
/* Random Number Generator (RNG) ********************************************/
#ifdef CONFIG_DEV_RANDOM
extern void up_rnginitialize(void);
#endif
/****************************************************************************
* Name: up_check_stack
*

1
arch/arm/src/stm32/Kconfig
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@ -320,6 +320,7 @@ config STM32_RNG
bool "RNG"
default n
depends on STM32_STM32F20XX || STM32_STM32F40XX
select ARCH_HAVE_RNG
config STM32_SDIO
bool "SDIO"

6
arch/arm/src/stm32/Make.defs
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@ -78,7 +78,7 @@ endif
ifeq ($(CONFIG_USBHOST),y)
ifeq ($(CONFIG_STM32_OTGFS),y)
CMN_CSRCS += stm32_otgfshost.c
CMN_CSRCS += stm32_otgfshost.c
endif
endif
@ -119,6 +119,10 @@ ifeq ($(CONFIG_DAC),y)
CHIP_CSRCS += stm32_dac.c
endif
ifeq ($(CONFIG_DEV_RANDOM),y)
CHIP_CSRCS += stm32_rng.c
endif
ifeq ($(CONFIG_PWM),y)
CHIP_CSRCS += stm32_pwm.c
endif

77
arch/arm/src/stm32/chip/stm32_rng.h Normal file
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@ -0,0 +1,77 @@
/************************************************************************************
* arch/arm/src/stm32/chip/stm32_rng.h
*
* Copyright (C) 2012 Max Holtzberg. All rights reserved.
* Author: Max Holtzberg <mh@uvc.de>
*
* 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.
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
************************************************************************************/
#ifndef __ARCH_ARM_STC_STM32_CHIP_STM32_RNG_H
#define __ARCH_ARM_STC_STM32_CHIP_STM32_RNG_H
/************************************************************************************
* Included Files
************************************************************************************/
#include <nuttx/config.h>
#include "chip.h"
/************************************************************************************
* Pre-processor Definitions
************************************************************************************/
/* Register Offsets *****************************************************************/
#define STM32_RNG_CR_OFFSET 0x0000 /* RNG Control Register */
#define STM32_RNG_SR_OFFSET 0x0004 /* RNG Status Register */
#define STM32_RNG_DR_OFFSET 0x0008 /* RNG Data Register */
/* Register Addresses ***************************************************************/
#define STM32_RNG_CR (STM32_RNG_BASE+STM32_RNG_CR_OFFSET)
#define STM32_RNG_SR (STM32_RNG_BASE+STM32_RNG_SR_OFFSET)
#define STM32_RNG_DR (STM32_RNG_BASE+STM32_RNG_DR_OFFSET)
/* Register Bitfield Definitions ****************************************************/
/* RNG Control Register */
#define RNG_CR_RNGEN (1 << 2) /* Bit 2: RNG enable */
#define RNG_CR_IE (1 << 3) /* Bit 3: Interrupt enable */
/* RNG Status Register */
#define RNG_SR_DRDY (1 << 0) /* Bit 0: Data ready */
#define RNG_SR_CECS (1 << 1) /* Bit 1: Clock error current status */
#define RNG_SR_SECS (1 << 2) /* Bit 2: Seed error current status */
#define RNG_SR_CEIS (1 << 5) /* Bit 5: Clock error interrupt status */
#define RNG_SR_SEIS (1 << 6) /* Bit 6: Seed error interrupt status */
#endif /* __ARCH_ARM_STC_STM32_CHIP_STM32_RNG_H */

264
arch/arm/src/stm32/stm32_rng.c Normal file
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@ -0,0 +1,264 @@
/****************************************************************************
* arch/arm/src/stm32/stm32_rng.c
*
* Copyright (C) 2012 Max Holtzberg. All rights reserved.
* Author: Max Holtzberg <mh@uvc.de>
*
* 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.
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <debug.h>
#include <errno.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include "up_arch.h"
#include "chip/stm32_rng.h"
#include "up_internal.h"
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int stm32_rnginitialize(void);
static int stm32_interrupt(int irq, void *context);
static void stm32_enable(void);
static void stm32_disable(void);
static ssize_t stm32_read(struct file *filep, char *buffer, size_t);
/****************************************************************************
* Private Types
****************************************************************************/
struct rng_dev_s
{
sem_t rd_devsem; /* Threads can only exclusively access the RNG */
sem_t rd_readsem; /* To block until the buffer is filled */
char *rd_buf;
size_t rd_buflen;
uint32_t rd_lastval;
bool rd_first;
};
/****************************************************************************
* Private Data
****************************************************************************/
static struct rng_dev_s g_rngdev;
static const struct file_operations g_rngops =
{
0, /* open */
0, /* close */
stm32_read, /* read */
0, /* write */
0, /* seek */
0 /* ioctl */
#ifndef CONFIG_DISABLE_POLL
,0 /* poll */
#endif
};
/****************************************************************************
* Private functions
****************************************************************************/
static int stm32_rnginitialize()
{
uint32_t regval;
vdbg("Initializing RNG\n");
memset(&g_rngdev, 0, sizeof(struct rng_dev_s));
sem_init(&g_rngdev.rd_devsem, 0, 1);
if (irq_attach(STM32_IRQ_RNG, stm32_interrupt))
{
/* We could not attach the ISR to the interrupt */
vdbg("Could not attach IRQ.\n");
return -EAGAIN;
}
/* Enable interrupts */
regval = getreg32(STM32_RNG_CR);
regval |= RNG_CR_IE;
putreg32(regval, STM32_RNG_CR);
up_enable_irq(STM32_IRQ_RNG);
return OK;
}
static void stm32_enable()
{
uint32_t regval;
g_rngdev.rd_first = true;
regval = getreg32(STM32_RNG_CR);
regval |= RNG_CR_RNGEN;
putreg32(regval, STM32_RNG_CR);
}
static void stm32_disable()
{
uint32_t regval;
regval = getreg32(STM32_RNG_CR);
regval &= ~RNG_CR_RNGEN;
putreg32(regval, STM32_RNG_CR);
}
static int stm32_interrupt(int irq, void *context)
{
uint32_t rngsr;
uint32_t data;
rngsr = getreg32(STM32_RNG_SR);
if ((rngsr & (RNG_SR_SEIS | RNG_SR_CEIS)) /* Check for error bits */
|| !(rngsr & RNG_SR_DRDY)) /* Data ready must be set */
{
/* This random value is not valid, we will try again. */
return OK;
}
data = getreg32(STM32_RNG_DR);
/* As required by the FIPS PUB (Federal Information Processing Standard
* Publication) 140-2, the first random number generated after setting the
* RNGEN bit should not be used, but saved for comparison with the next
* generated random number. Each subsequent generated random number has to be
* compared with the previously generated number. The test fails if any two
* compared numbers are equal (continuous random number generator test).
*/
if (g_rngdev.rd_first)
{
g_rngdev.rd_first = false;
g_rngdev.rd_lastval = data;
return OK;
}
if (g_rngdev.rd_lastval == data)
{
/* Two subsequent same numbers, we will try again. */
return OK;
}
/* If we get here, the random number is valid. */
g_rngdev.rd_lastval = data;
if (g_rngdev.rd_buflen >= 4)
{
g_rngdev.rd_buflen -= 4;
*(uint32_t*)&g_rngdev.rd_buf[g_rngdev.rd_buflen] = data;
}
else
{
while (g_rngdev.rd_buflen > 0)
{
g_rngdev.rd_buf[--g_rngdev.rd_buflen] = (char)data;
data >>= 8;
}
}
if (g_rngdev.rd_buflen == 0)
{
/* Buffer filled, stop further interrupts. */
stm32_disable();
sem_post(&g_rngdev.rd_readsem);
}
return OK;
}
/****************************************************************************
* Name: stm32_read
****************************************************************************/
static ssize_t stm32_read(struct file *filep, char *buffer, size_t buflen)
{
if (sem_wait(&g_rngdev.rd_devsem) != OK)
{
return -errno;
}
else
{
/* We've got the semaphore. */
/* Initialize semaphore with 0 for blocking until the buffer is filled from
* interrupts.
*/
sem_init(&g_rngdev.rd_readsem, 0, 1);
g_rngdev.rd_buflen = buflen;
g_rngdev.rd_buf = buffer;
/* Enable RNG with interrupts */
stm32_enable();
/* Wait until the buffer is filled */
sem_wait(&g_rngdev.rd_readsem);
/* Free RNG for next use */
sem_post(&g_rngdev.rd_devsem);
return buflen;
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
void up_rnginitialize()
{
stm32_rnginitialize();
register_driver("/dev/random", &g_rngops, 0444, NULL);
}