arch/arm/src/armv7-m: Implement SYSTICK timer driver

arch/arm/src/armv7-m/Kconfig

@@ -255,3 +255,9 @@ config ARMV7M_ITMSYSLOG_SWODIV
 	range 1 8192
 
 endif # ARMV7M_ITMSYSLOG
+
+config ARMV7M_SYSTICK
+	bool "SysTick timer driver"
+	depends on TIMER
+	---help---
+		Enable SysTick timer driver.

arch/arm/src/armv7-m/systick.h

@@ -0,0 +1,91 @@
+/****************************************************************************
+ * arch/arm/src/armv7-m/systick.h
+ *
+ *   Copyright (C) 2018 Pinecone Inc. All rights reserved.
+ *   Author: Xiang Xiao <xiaoxiang@pinecone.net>
+ *
+ * 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_SRC_ARMV7_M_SYSTICK_H
+#define __ARCH_ARM_SRC_ARMV7_M_SYSTICK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/timers/timer.h>
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Name: systick_initialize
+ *
+ * Description:
+ *   This function initialize SYSTICK hardware module which is part of NVIC
+ *   and return an instance of a "lower half" timer interface.
+ *
+ * Input parameters:
+ *   coreclk - false if SYSTICK working clock come from the external
+ *     reference clock, otherwise true.
+ *   freq - The clock frequency in Hz. If freq is zero, calculate the value
+ *     from NVIC_SYSTICK_CALIB register.
+ *   minor - The timer driver minor number, skip the registration if minor
+ *     < 0.
+ *
+ * Returned Value:
+ *   On success, a non-NULL timer_lowerhalf_s is returned to the caller.
+ *   In the event of any failure, a NULL value is returned.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ARMV7M_SYSTICK
+struct timer_lowerhalf_s *systick_initialize(bool coreclk, unsigned int freq,
+                                             int minor);
+#else
+#  define systick_initialize(coreclk, freq, minor) NULL
+#endif /* CONFIG_ARMV7M_SYSTICK */
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ARCH_ARM_SRC_ARMV7_M_SYSTICK_H */

arch/arm/src/armv7-m/up_systick.c

@@ -0,0 +1,331 @@
+/****************************************************************************
+ * arch/arm/src/armv7-m/up_systick.c
+ *
+ *   Copyright (C) 2018 Pinecone Inc. All rights reserved.
+ *   Author: Xiang Xiao <xiaoxiang@pinecone.net>
+ *
+ * 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 <nuttx/config.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/irq.h>
+
+#include <stdio.h>
+
+#include "nvic.h"
+#include "systick.h"
+#include "up_arch.h"
+
+#ifdef CONFIG_ARMV7M_SYSTICK
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define NVIC_IRQ_SYSTICK    15          /* Vector 15: System tick */
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/* This structure provides the private representation of the "lower-half"
+ * driver state structure.  This structure must be cast-compatible with the
+ * timer_lowerhalf_s structure.
+ */
+
+struct systick_lowerhalf_s
+{
+  const struct timer_ops_s *ops;        /* Lower half operations */
+  uint32_t                  freq;       /* Timer working clock frequency(Hz) */
+  tccb_t                    callback;   /* Current user interrupt callback */
+  void                     *arg;        /* Argument passed to upper half callback */
+  uint32_t                 *next_interval;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int systick_start(FAR struct timer_lowerhalf_s *lower_);
+static int systick_stop(FAR struct timer_lowerhalf_s *lower_);
+static int systick_getstatus(FAR struct timer_lowerhalf_s *lower_,
+                             FAR struct timer_status_s *status);
+static int systick_settimeout(FAR struct timer_lowerhalf_s *lower_,
+                              uint32_t timeout);
+static void systick_setcallback(FAR struct timer_lowerhalf_s *lower_,
+                                tccb_t callback, FAR void *arg);
+static int systick_maxtimeout(FAR struct timer_lowerhalf_s *lower_,
+                              uint32_t *maxtimeout);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct timer_ops_s g_systick_ops =
+{
+  .start       = systick_start,
+  .stop        = systick_stop,
+  .getstatus   = systick_getstatus,
+  .settimeout  = systick_settimeout,
+  .setcallback = systick_setcallback,
+  .maxtimeout  = systick_maxtimeout,
+};
+
+static struct systick_lowerhalf_s g_systick_lower =
+{
+  .ops = &g_systick_ops,
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static inline uint64_t usec_from_count(uint32_t count, uint32_t freq)
+{
+  return (uint64_t)count * USEC_PER_SEC / freq;
+}
+
+static inline uint64_t usec_to_count(uint32_t usec, uint32_t freq)
+{
+  return (uint64_t)usec * freq / USEC_PER_SEC;
+}
+
+static bool systick_is_running(void)
+{
+  return !!(getreg32(NVIC_SYSTICK_CTRL) & NVIC_SYSTICK_CTRL_ENABLE);
+}
+
+static bool systick_irq_pending(struct systick_lowerhalf_s *lower)
+{
+  if (lower->next_interval)
+    {
+      return false; /* Interrupt is in process */
+    }
+  else
+    {
+      return !!(getreg32(NVIC_INTCTRL) & NVIC_INTCTRL_PENDSTSET);
+    }
+}
+
+static int systick_start(FAR struct timer_lowerhalf_s *lower_)
+{
+  putreg32(0, NVIC_SYSTICK_CURRENT);
+  modifyreg32(NVIC_SYSTICK_CTRL, 0, NVIC_SYSTICK_CTRL_ENABLE);
+  return 0;
+}
+
+static int systick_stop(FAR struct timer_lowerhalf_s *lower_)
+{
+  modifyreg32(NVIC_SYSTICK_CTRL, NVIC_SYSTICK_CTRL_ENABLE, 0);
+  return 0;
+}
+
+static int systick_getstatus(FAR struct timer_lowerhalf_s *lower_,
+                             FAR struct timer_status_s *status)
+{
+  struct systick_lowerhalf_s *lower = (struct systick_lowerhalf_s *)lower_;
+  irqstate_t flags = enter_critical_section();
+
+  status->flags    = lower->callback ? TCFLAGS_HANDLER : 0;
+  status->flags   |= systick_is_running() ? TCFLAGS_ACTIVE : 0;
+  status->timeout  = usec_from_count(getreg32(NVIC_SYSTICK_RELOAD),
+                                     lower->freq);
+  status->timeleft = usec_from_count(getreg32(NVIC_SYSTICK_CURRENT),
+                                     lower->freq);
+
+  if (systick_irq_pending(lower))
+    {
+      /* Interrupt is pending and the timer wrap happen? */
+
+      if (status->timeleft)
+        {
+          /* Make timeout-timeleft equal the real elapsed time */
+
+          status->timeout += status->timeout - status->timeleft;
+          status->timeleft = 0;
+        }
+    }
+  else if (status->timeleft == 0)
+    {
+      status->timeleft = status->timeout;
+    }
+
+  leave_critical_section(flags);
+  return 0;
+}
+
+static int systick_settimeout(FAR struct timer_lowerhalf_s *lower_,
+                              uint32_t timeout)
+{
+  struct systick_lowerhalf_s *lower = (struct systick_lowerhalf_s *)lower_;
+
+  irqstate_t flags = enter_critical_section();
+  if (lower->next_interval)
+    {
+      /* If the timer callback is in the process,
+       * delay the update to timer interrupt handler.
+       */
+
+      *lower->next_interval = timeout;
+    }
+  else
+    {
+      uint32_t reload;
+
+      reload = usec_to_count(timeout, lower->freq);
+      putreg32(reload, NVIC_SYSTICK_RELOAD);
+      if (systick_is_running())
+        {
+          if (reload != getreg32(NVIC_SYSTICK_CURRENT))
+            {
+              putreg32(0, NVIC_SYSTICK_CURRENT);
+            }
+        }
+    }
+
+  leave_critical_section(flags);
+  return 0;
+}
+
+static void systick_setcallback(FAR struct timer_lowerhalf_s *lower_,
+                                CODE tccb_t callback, FAR void *arg)
+{
+  struct systick_lowerhalf_s *lower = (struct systick_lowerhalf_s *)lower_;
+
+  irqstate_t flags = enter_critical_section();
+  lower->callback  = callback;
+  lower->arg       = arg;
+  leave_critical_section(flags);
+}
+
+static int systick_maxtimeout(FAR struct timer_lowerhalf_s *lower_,
+                              uint32_t *maxtimeout)
+{
+  uint64_t maxtimeout64 = usec_from_count(
+    NVIC_SYSTICK_RELOAD_MASK, g_systick_lower.freq);
+
+  if (maxtimeout64 > UINT32_MAX)
+    {
+      *maxtimeout = UINT32_MAX;
+    }
+  else
+    {
+      *maxtimeout = maxtimeout64;
+    }
+
+  return 0;
+}
+
+static int systick_interrupt(int irq, FAR void *context, FAR void *arg)
+{
+  struct systick_lowerhalf_s *lower = arg;
+
+  if (lower->callback && systick_is_running())
+    {
+      uint32_t reload = getreg32(NVIC_SYSTICK_RELOAD);
+      uint32_t interval = usec_from_count(reload, lower->freq);
+      uint32_t next_interval = interval;
+
+      lower->next_interval = &next_interval;
+      if (lower->callback(&next_interval, lower->arg))
+        {
+          if (next_interval && next_interval != interval)
+            {
+              reload = usec_to_count(next_interval, lower->freq);
+              putreg32(reload, NVIC_SYSTICK_RELOAD);
+              putreg32(0, NVIC_SYSTICK_CURRENT);
+            }
+        }
+      else
+        {
+          modifyreg32(NVIC_SYSTICK_CTRL, NVIC_SYSTICK_CTRL_ENABLE, 0);
+        }
+
+      lower->next_interval = NULL;
+    }
+
+  return 0;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+struct timer_lowerhalf_s *systick_initialize(bool coreclk,
+                                             unsigned int freq, int minor)
+{
+  struct systick_lowerhalf_s *lower = (struct systick_lowerhalf_s *)&g_systick_lower;
+
+  /* Calculate the working clock frequency if need */
+
+  if (freq == 0)
+    {
+      uint32_t calib = getreg32(NVIC_SYSTICK_CALIB);
+      uint32_t tenms = calib & NVIC_SYSTICK_CALIB_TENMS_MASK;
+      lower->freq = 100 * (tenms + 1);
+    }
+  else
+    {
+      lower->freq = freq;
+    }
+
+  /* Disable SYSTICK, but enable interrupt */
+
+  if (coreclk)
+    {
+      putreg32(NVIC_SYSTICK_CTRL_CLKSOURCE | NVIC_SYSTICK_CTRL_TICKINT, NVIC_SYSTICK_CTRL);
+    }
+  else
+    {
+      putreg32(NVIC_SYSTICK_CTRL_TICKINT, NVIC_SYSTICK_CTRL);
+    }
+
+  irq_attach(NVIC_IRQ_SYSTICK, systick_interrupt, lower);
+  up_enable_irq(NVIC_IRQ_SYSTICK);
+
+  /* Register the timer driver if need */
+
+  if (minor >= 0)
+    {
+      char devname[32];
+
+      sprintf(devname, "/dev/timer%d", minor);
+      timer_register(devname, (struct timer_lowerhalf_s *)lower);
+    }
+
+  return (struct timer_lowerhalf_s *)lower;
+}
+
+#endif /* CONFIG_ARMV7M_SYSTICK */