drivers/capture: add fake capture driver for testing and development

This commit introduces a software-based fake capture driver that simulates
a 10Hz square wave with 50% duty cycle, enabling development and testing
of capture-related applications without requiring real hardware.

Background:
The capture driver subsystem requires hardware support (timers with input
capture functionality) to measure external signal frequency and duty cycle.
During development, testing, or on platforms without capture hardware, it's
difficult to develop and test applications that use the capture API.

Problem:
Without a fake/simulator driver:
- Developers cannot test capture applications without specific hardware
- Continuous Integration (CI) systems cannot run capture-related tests
- Applications cannot be developed on platforms lacking capture hardware
- Testing edge notification features requires complex hardware setup
- Difficult to reproduce specific timing scenarios for debugging

Solution:
This commit provides a software-simulated capture driver that generates
predictable capture events using a watchdog timer. The fake driver
produces a square wave signal at 10Hz frequency with 50% duty cycle,
allowing applications to test the full capture API without hardware.

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

Author: Donny9

drivers/drivers_initialize.c

@@ -51,6 +51,7 @@
 #include <nuttx/syslog/syslog_console.h>
 #include <nuttx/thermal.h>
 #include <nuttx/timers/ptp_clock_dummy.h>
+#include <nuttx/timers/capture.h>
 #include <nuttx/trace.h>
 #include <nuttx/usrsock/usrsock_rpmsg.h>
 #include <nuttx/vhost/vhost.h>
@@ -298,5 +299,9 @@ void drivers_initialize(void)
   ptp_clock_dummy_initialize(0);
 #endif
 
+#ifdef CONFIG_FAKE_CAPTURE
+  fake_capture_initialize(2);
+#endif
+
   drivers_trace_end();
 }

drivers/timers/CMakeLists.txt

@@ -84,6 +84,10 @@ endif()
 
 if(CONFIG_CAPTURE)
   list(APPEND SRCS capture.c)
+
+  if(CONFIG_FAKE_CAPTURE)
+    list(APPEND SRCS fake_capture.c)
+  endif()
 endif()
 
 if(CONFIG_GOLDFISH_TIMER)

drivers/timers/Kconfig

@@ -102,6 +102,13 @@ config CAPTURE_NOTIFY
 		occurs.  If the hardware will support notification, then this
 		configuration should be set to enable the capability.
 
+config FAKE_CAPTURE
+	bool "Fake Capture Driver"
+	default n
+	depends on CAPTURE_NSIGNALS > 0
+	---help---
+		Enables a fake capture driver for testing purposes.
+
 endif # CAPTURE
 
 config TIMER

drivers/timers/Make.defs

@@ -114,6 +114,11 @@ endif
 
 ifeq ($(CONFIG_CAPTURE),y)
   CSRCS += capture.c
+
+  ifeq ($(CONFIG_FAKE_CAPTURE),y)
+    CSRCS += fake_capture.c
+  endif
+
   TMRDEPPATH = --dep-path timers
   TMRVPATH = :timers
 endif