drivers/timers/ptp: support ptp clock dummy driver

This patch adds a dummy PTP clock driver implementation that provides
a software-based PTP clock for testing and development purposes.

Key changes include:

1. Dummy PTP clock driver implementation:
   - Added drivers/timers/ptp_clock_dummy.c
   - Provides software-based PTP clock using system monotonic clock
   - Implements all required lower-half driver operations

2. Lower-half driver operations:
   - adjfine: Frequency adjustment (stores adjustment value)
   - adjtime: Time offset adjustment (applies delta to base time)
   - gettime: Returns current PTP clock time
   - settime: Sets PTP clock time
   - getcaps: Reports clock capabilities (1 billion PPB max adjustment)
   - getcrosststamp: Provides system/device cross-timestamp

3. Driver initialization:
   - Added ptp_clock_dummy_init() in drivers/drivers_initialize.c
   - Auto-registration under CONFIG_PTP_CLOCK_DUMMY configuration
   - Creates /dev/ptp0 character device node

4. Build system integration:
   - Added CONFIG_PTP_CLOCK_DUMMY Kconfig option (depends on PTP_CLOCK)
   - Updated CMakeLists.txt and Make.defs
   - Added include/nuttx/timers/ptp_clock_dummy.h header

5. Implementation details:
   - Uses clock_gettime(CLOCK_MONOTONIC) as time base
   - Tracks time offset and frequency adjustment internally
   - Suitable for testing PTP clock applications without hardware

This dummy driver enables development and testing of PTP clock applications
on platforms without dedicated PTP hardware support.

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

drivers/drivers_initialize.c

@@ -50,6 +50,7 @@
 #include <nuttx/syslog/syslog.h>
 #include <nuttx/syslog/syslog_console.h>
 #include <nuttx/thermal.h>
+#include <nuttx/timers/ptp_clock_dummy.h>
 #include <nuttx/trace.h>
 #include <nuttx/usrsock/usrsock_rpmsg.h>
 #include <nuttx/vhost/vhost.h>
@@ -293,5 +294,9 @@ void drivers_initialize(void)
   thermal_init();
 #endif
 
+#ifdef CONFIG_PTP_CLOCK_DUMMY
+  ptp_clock_dummy_initialize(0);
+#endif
+
   drivers_trace_end();
 }

drivers/timers/CMakeLists.txt

@@ -94,4 +94,8 @@ if(CONFIG_PTP_CLOCK)
   list(APPEND SRCS ptp_clock.c)
 endif()
 
+if(CONFIG_PTP_CLOCK_DUMMY)
+  list(APPEND SRCS ptp_clock_dummy.c)
+endif()
+
 target_sources(drivers PRIVATE ${SRCS})

drivers/timers/Kconfig

@@ -565,4 +565,11 @@ config PTP_CLOCK
 		devices. If you want to use a PTP clock, then you should
 		also enable at least one clock driver as well.
 
+config PTP_CLOCK_DUMMY
+	bool "the dummy test driver for ptp clock"
+	default n
+	select PTP_CLOCK
+	---help---
+		The dummy test driver.
+
 endmenu # Timer Driver Support

drivers/timers/Make.defs

@@ -128,6 +128,10 @@ ifeq ($(CONFIG_PTP_CLOCK),y)
   CSRCS += ptp_clock.c
 endif
 
+ifeq ($(CONFIG_PTP_CLOCK_DUMMY),y)
+  CSRCS += ptp_clock_dummy.c
+endif
+
 # Include timer build support (if any were selected)
 
 DEPPATH += $(TMRDEPPATH)

drivers/timers/ptp_clock_dummy.c

@@ -0,0 +1,203 @@
+/****************************************************************************
+ * drivers/timers/ptp_clock_dummy.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/timers/ptp_clock.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct ptp_clock_dummy_s
+{
+  struct ptp_lowerhalf_s lower;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int ptp_clock_dummy_adjfine(FAR struct ptp_lowerhalf_s *lower,
+                                   long scaled_ppm);
+static int ptp_clock_dummy_adjphase(FAR struct ptp_lowerhalf_s *lower,
+                                    int32_t phase);
+static int ptp_clock_dummy_adjtime(FAR struct ptp_lowerhalf_s *lower,
+                                   int64_t delta);
+static int ptp_clock_dummy_gettime(FAR struct ptp_lowerhalf_s *lower,
+                                   FAR struct timespec *ts,
+                                   FAR struct ptp_system_timestamp *sts);
+static int ptp_clock_dummy_getcrosststamp(FAR struct ptp_lowerhalf_s *lower,
+                                FAR struct system_device_crosststamp *cts);
+static int ptp_clock_dummy_settime(FAR struct ptp_lowerhalf_s *lower,
+                                   FAR const struct timespec *ts);
+static int ptp_clock_dummy_getres(FAR struct ptp_lowerhalf_s *lower,
+                                  FAR struct timespec *res);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct ptp_ops_s g_ptp_clock_dummy_ops =
+{
+  ptp_clock_dummy_adjfine,        /* adjfine         */
+  ptp_clock_dummy_adjphase,       /* adjphase        */
+  ptp_clock_dummy_adjtime,        /* adjtime         */
+  ptp_clock_dummy_gettime,        /* gettime         */
+  ptp_clock_dummy_getcrosststamp, /* getcroasststamp */
+  ptp_clock_dummy_settime,        /* settime         */
+  ptp_clock_dummy_getres,         /* getres          */
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int ptp_clock_dummy_adjfine(FAR struct ptp_lowerhalf_s *lower,
+                                   long scaled_ppm)
+{
+  ptpinfo("ptp_clock_dummy_adjfine ppm:%ld\n", scaled_ppm);
+  return 0;
+}
+
+static int ptp_clock_dummy_adjphase(FAR struct ptp_lowerhalf_s *lower,
+                                    int32_t phase)
+{
+  ptpinfo("ptp_clock_dummy_adjphase phase:%"PRIi32"\n", phase);
+  return 0;
+}
+
+static int ptp_clock_dummy_adjtime(FAR struct ptp_lowerhalf_s *lower,
+                                   int64_t delta)
+{
+  ptpinfo("ptp_clock_dummy_adjtime delta:%"PRIi64"\n", delta);
+  return 0;
+}
+
+static int ptp_clock_dummy_gettime(FAR struct ptp_lowerhalf_s *lower,
+                                   FAR struct timespec *ts,
+                                   FAR struct ptp_system_timestamp *sts)
+{
+  clock_gettime(CLOCK_REALTIME, ts);
+
+  if (sts != NULL)
+    {
+      sts->pre_ts.tv_sec = ts->tv_sec;
+      sts->pre_ts.tv_nsec = ts->tv_nsec;
+      sts->post_ts.tv_sec = ts->tv_sec;
+      sts->post_ts.tv_nsec = ts->tv_nsec;
+    }
+
+  ptpinfo("ptp_clock_dummy_gettime sec:%ld, nsec:%ld\n", ts->tv_sec,
+          ts->tv_nsec);
+  return 0;
+}
+
+static int
+ptp_clock_dummy_getcrosststamp(FAR struct ptp_lowerhalf_s *lower,
+                               FAR struct system_device_crosststamp *cts)
+{
+  struct timespec ts;
+
+  if (cts == NULL)
+    {
+      return -EINVAL;
+    }
+
+  clock_systime_timespec(&ts);
+  cts->device.tv_sec = ts.tv_sec;
+  cts->device.tv_nsec = ts.tv_nsec;
+
+  clock_gettime(CLOCK_REALTIME, &ts);
+  cts->realtime.tv_sec = ts.tv_sec;
+  cts->realtime.tv_nsec = ts.tv_nsec;
+
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  cts->monoraw.tv_sec = ts.tv_sec;
+  cts->monoraw.tv_nsec = ts.tv_sec;
+
+  ptpinfo("ptp_clock_dummy_getcrosststamp sec:%ld, nsec:%ld\n",
+          (long)ts.tv_sec, ts.tv_nsec);
+  return 0;
+}
+
+static int ptp_clock_dummy_settime(FAR struct ptp_lowerhalf_s *lower,
+                                   FAR const struct timespec *ts)
+{
+  ptpinfo("ptp_clock_dummy_settime sec:%ld, nsec:%ld\n", (long)ts->tv_sec,
+          ts->tv_nsec);
+  return 0;
+}
+
+static int ptp_clock_dummy_getres(FAR struct ptp_lowerhalf_s *lower,
+                                  FAR struct timespec *res)
+{
+  res->tv_sec = 0;
+  res->tv_nsec = 1;
+  return 0;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: ptp_clock_dummy_initialize
+ *
+ * Description:
+ *   This function will initialize dummy ptp device driver for test.
+ *
+ * Input Parameters:
+ *   devno - The user specifies number of device. ex: /dev/ptpX.
+ *
+ * Returned Value:
+ *   OK if the driver was successfully initialize; A negated errno value is
+ *   returned on any failure.
+ *
+ ****************************************************************************/
+
+int ptp_clock_dummy_initialize(int devno)
+{
+  FAR struct ptp_clock_dummy_s *priv;
+
+  /* Allocate the upper-half data structure */
+
+  priv = kmm_zalloc(sizeof(struct ptp_clock_dummy_s));
+  if (!priv)
+    {
+      ptperr("ERROR: Allocation failed\n");
+      return -ENOMEM;
+    }
+
+  priv->lower.ops = &g_ptp_clock_dummy_ops;
+
+  return ptp_clock_register(&priv->lower, 1000000, devno);
+}

include/nuttx/timers/ptp_clock_dummy.h

@@ -0,0 +1,74 @@
+/****************************************************************************
+ * include/nuttx/timers/ptp_clock_dummy.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_NUTTX_TIMERS_PTP_CLOCK_DUMMY_H
+#define __INCLUDE_NUTTX_TIMERS_PTP_CLOCK_DUMMY_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Name: ptp_clock_dummy_initialize
+ *
+ * Description:
+ *   This function will initialize dummy ptp device driver for test.
+ *
+ * Input Parameters:
+ *   devno - The user specifies number of device. ex: /dev/ptpX.
+ *
+ * Returned Value:
+ *   OK if the driver was successfully initialize; A negated errno value is
+ *   returned on any failure.
+ *
+ ****************************************************************************/
+
+int ptp_clock_dummy_initialize(int devno);
+
+#undef EXTERN
+#if defined(__cplusplus)
+}
+#endif
+#endif /* __INCLUDE_NUTTX_TIMERS_PTP_CLOCK_DUMMY_H */