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

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5207 42af7a65-404d-4744-a932-0658087f49c3

4 files changed, 347 insertions, 1 deletions

diff --git a/nuttx/arch/arm/src/stm32/Kconfig b/nuttx/arch/arm/src/stm32/Kconfig
index fe89119a4..2f9100236 100644
--- a/nuttx/arch/arm/src/stm32/Kconfig
+++ b/nuttx/arch/arm/src/stm32/Kconfig
@@ -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"
diff --git a/nuttx/arch/arm/src/stm32/Make.defs b/nuttx/arch/arm/src/stm32/Make.defs
index e52962977..ef14b48c1 100644
--- a/nuttx/arch/arm/src/stm32/Make.defs
+++ b/nuttx/arch/arm/src/stm32/Make.defs
@@ -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
diff --git a/nuttx/arch/arm/src/stm32/chip/stm32_rng.h b/nuttx/arch/arm/src/stm32/chip/stm32_rng.h
new file mode 100644
index 000000000..5e31d5817
--- /dev/null
+++ b/nuttx/arch/arm/src/stm32/chip/stm32_rng.h
@@ -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 */
diff --git a/nuttx/arch/arm/src/stm32/stm32_rng.c b/nuttx/arch/arm/src/stm32/stm32_rng.c
new file mode 100644
index 000000000..38e8108fe
--- /dev/null
+++ b/nuttx/arch/arm/src/stm32/stm32_rng.c
@@ -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);
+}