sim/ft2232h: Add FT2232H GPIO integration on NuttX sim

Documentation/platforms/sim/index.rst

@@ -15,3 +15,4 @@ The following Simulator/Emulators are supported:
    network_linux
    network_vpnkit
    sim_gpiochip
+   sim_ft2232h_gpio

Documentation/platforms/sim/sim/boards/sim/index.rst

@@ -651,6 +651,27 @@ fb
 A simple configuration used for some basic (non-graphic) debug of the
 framebuffer character drivers using ``apps/examples/fb``.
 
+ft2232h_gpio
+------------
+
+This example requires you have a FT2232H I/O Expander board (i.e. CJMCU-2232HL)
+connected to your host computer (read the "Sim FTDI GPIO Driver" documentation)
+to read/write external GPIO pins.
+
+Usage example:
+
+.. code:: console
+
+   nsh> gpio -o 1 /dev/gpio20
+   Driver: /dev/gpio20
+     Input pin:     Value=1
+   nsh> gpio -o 1 /dev/gpio27
+   Driver: /dev/gpio27
+     Output pin:    Value=0
+     Writing:       Value=1
+     Verify:        Value=1
+   nsh>
+
 ipforward
 ---------
 

Documentation/platforms/sim/sim_ft2232h_gpio.rst

@@ -0,0 +1,209 @@
+=====================================
+Sim FTDI GPIO Driver (Using libftdi1)
+=====================================
+
+Overview
+========
+
+The NuttX simulation (sim) already has a GPIO Chip driver that provides a mechanism use GPIO to control external devices. However that solution depends on having a driver to Linux side and that adds more overhead.
+
+This FTDI driver allows a direct use of libftdi1 to control up to 8 GPIOs.
+
+This driver is particularly useful for:
+
+- Testing GPIO-based applications in a simulated environment with real hardware
+- Interfacing with USB-to-GPIO adapters from NuttX simulation
+- Developing and debugging GPIO drivers without dedicated embedded hardware
+
+Host Prepare
+============
+
+Preparation required on the host side:
+
+- Hardware module required: FT2232H module like the CJMCU-2232HL module
+- A udev rule on Linux side to avoid using the FT2232H as USB/Serial:
+
+.. code-block:: console
+
+   $ cat /etc/udev/rules.d/99-ft2232h-d2xx.rules 
+   ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", ATTRS{product}=="FTDI Device", MODE="0666"
+
+- The libftdi1-dev installed on your system.
+
+Architecture
+============
+
+The driver consists of two layers:
+
+1. **NuttX Layer** (``sim_gpiochip.c``): Implements the NuttX ``ioexpander_dev_s``
+   interface, providing standard GPIO operations to upper-layer NuttX drivers.
+
+2. **Host Layer** (``sim_ftdi_gpiochip.c``): Interfaces directly with libftdio1 to initialize and to provide the functions to control the GPIOs.
+
+.. uml::
+
+   @startuml
+   skinparam componentStyle rectangle
+   skinparam defaultFontName Monospaced
+
+   [NuttX Application] as app
+   [GPIO Lower Half\n(gpio_lower_half)] as gpio
+   [sim_gpiochip.c\n(ioexpander_dev_s)] as ioex
+   note right of ioex : NuttX ioexpander interface
+   [sim_ftdi_gpiochip.c\n(host interface)] as sim
+   note right of sim : Linux host GPIO interface
+   [libftdi1] as ftdi
+   note right of ftdi : Linux library to control FT2232H
+
+   app --> gpio
+   gpio --> ioex
+   ioex --> sim
+   sim --> ftdi
+   @enduml
+
+Header Files
+============
+
+-  ``arch/sim/src/sim/sim_gpiochip.h``: Host GPIO chip interface definitions and function prototypes.
+
+-  ``include/nuttx/ioexpander/ioexpander.h``: Standard NuttX IO expander interface.
+
+-  ``include/nuttx/ioexpander/gpio.h``: NuttX GPIO interface definitions.
+
+Configuration Options
+=====================
+
+The following configuration options are relevant to this driver:
+
+- ``CONFIG_SIM_GPIOCHIP_FTDI``: Enable the FTDI/FT2232H driver support.
+
+Supported Operations
+====================
+
+The driver supports the following GPIO operations:
+
+Direction Control
+-----------------
+
+.. code-block:: c
+
+   int sim_gpiochip_direction(struct ioexpander_dev_s *dev,
+                              uint8_t pin, int direction);
+
+Set GPIO pin direction. Supported directions:
+
+- ``IOEXPANDER_DIRECTION_IN``: Configure as input
+- ``IOEXPANDER_DIRECTION_OUT``: Configure as output
+- ``IOEXPANDER_DIRECTION_OUT_OPENDRAIN``: Configure as open-drain output
+
+Read/Write Pin
+--------------
+
+.. code-block:: c
+
+   int sim_gpiochip_readpin(struct ioexpander_dev_s *dev, uint8_t pin,
+                            bool *value);
+   int sim_gpiochip_writepin(struct ioexpander_dev_s *dev, uint8_t pin,
+                             bool value);
+
+Read or write the value of a GPIO pin.
+
+Host Layer API
+==============
+
+The host layer (``sim_ftdi_gpiochip.c``) provides the following functions:
+
+.. code-block:: c
+
+   /* Allocate and initialize a host GPIO chip device */
+   struct host_gpiochip_dev *host_gpiochip_alloc(uint8_t pins_dir);
+
+   /* Free a host GPIO chip device */
+   void host_gpiochip_free(struct host_gpiochip_dev *dev);
+
+   /* Set GPIO pin direction */
+   int host_gpiochip_direction(struct host_gpiochip_dev *dev,
+                               uint8_t pin, bool input);
+
+   /* Read GPIO pin value */
+   int host_gpiochip_readpin(struct host_gpiochip_dev *dev,
+                             uint8_t pin, bool *value);
+
+   /* Write GPIO pin value */
+   int host_gpiochip_writepin(struct host_gpiochip_dev *dev,
+                              uint8_t pin, bool value);
+
+   /* Request GPIO interrupt */
+   int host_gpiochip_irq_request(struct host_gpiochip_dev *dev,
+                                 uint8_t pin, uint16_t cfgset);
+
+   /* Check if GPIO interrupt is active */
+   bool host_gpiochip_irq_active(struct host_gpiochip_dev *dev, uint8_t pin);
+
+   /* Get GPIO line information */
+   int host_gpiochip_get_line(struct host_gpiochip_dev *priv,
+                              uint8_t pin, bool *input);
+
+Linux Kernel Version Requirements
+=================================
+
+The driver uses Linux GPIO v2 ABI, which requires:
+
+- **Linux kernel >= 6.8.0**: Full functionality with GPIO v2 API support.
+- **Linux kernel < 6.8.0**: The driver compiles but provides stub implementations
+  that return 0 or NULL.
+
+Usage Example
+=============
+
+Initialization
+--------------
+
+Application Usage
+-----------------
+
+After initialization, GPIO pins can be accessed through standard NuttX GPIO interface:
+
+.. code-block:: c
+
+   #include <fcntl.h>
+   #include <sys/ioctl.h>
+   #include <nuttx/ioexpander/gpio.h>
+
+   int main(void)
+   {
+     int fd;
+     bool value;
+
+     /* Open GPIO device */
+     fd = open("/dev/gpio20", O_RD);
+     if (fd < 0)
+       {
+         return -1;
+       }
+
+     /* Read GPIO value */
+     ioctl(fd, GPIOC_READ, &value);
+     printf("GPIO value: %d\n", value);
+
+     close(fd);
+     return 0;
+   }
+
+Files
+=====
+
+-  ``arch/sim/src/sim/sim_gpiochip.c``: NuttX IO expander implementation
+-  ``arch/sim/src/sim/posix/sim_ftdi_gpiochip.c``: Linux host GPIO interface
+-  ``arch/sim/src/sim/sim_gpiochip.h``: Host GPIO chip header file
+
+Limitations
+===========
+
+1. **Polling-based interrupts**: Due to simulation constraints, interrupts are
+   implemented using polling rather than true hardware interrupts.
+
+3. **Pin count**: Limited to 8 pins of SYNBB AD0-7.
+
+4. **Invert option**: The ``IOEXPANDER_OPTION_INVERT`` option is not yet implemented.
+

arch/sim/Kconfig

@@ -696,7 +696,7 @@ config SIM_SPIDEV_NAME
 endif
 
 config SIM_GPIOCHIP
-	bool "Simulated gpiochip"
+	bool "Support to Control External GPIO devices"
 	default n
 	depends on IOEXPANDER
 	---help---
@@ -709,23 +709,43 @@ choice
 	default SIM_GPIOCHIP_LINUX
 
 config SIM_GPIOCHIP_LINUX
-	bool "Linux Gpiochip Character Dev"
+	bool "Linux GPIOCHIP Character Dev"
 	depends on HOST_LINUX
 	---help---
 		Attach a Linux Gpiochip via the character device
 		interface. To achieve a SPI port on Linux host, it is
 		recommended to use a USB<>GPIO device such as CH341A/B.
 
+config SIM_GPIOCHIP_FTDI
+	bool "FTDI I/O Expander (i.e. FT2232H) as GPIOCHIP"
+	---help---
+		It is possible to use a USB FTDI FTDI to support external
+		devices connected to the computer. These devices could be GPIO,
+		I2C or SPI and NuttX on SIM will see it as a real device.
+
 endchoice
 
 config SIM_GPIOCHIP_NAME
 	string "the name of host gpiochip dev to attach to simulator"
 	default "/dev/gpiochip0"
+	depends on SIM_GPIOCHIP_LINUX
 	---help---
-		This is the name of the gpiochip device on the host implementation to
-		attach to the simulator driver.
+		This is the name of the gpiochip device on the host
+		implementation to attach to the simulator driver.
 
-endif
+if SIM_GPIOCHIP_FTDI
+
+config SIM_FTDI_VID
+	hex "USB Vendor ID"
+	default 0x0403
+
+config SIM_FTDI_PID
+	hex "USB Product ID"
+	default 0x6010
+
+endif # SIM_FTDI
+
+endif # SIM_GPIOCHIP
 
 menu "Simulated UART"
 

arch/sim/src/Makefile

@@ -262,9 +262,18 @@ ifeq ($(CONFIG_SIM_SPI_LINUX),y)
   HOSTSRCS += sim_linuxspi.c
 endif
 
+ifeq ($(CONFIG_SIM_GPIOCHIP),y)
+  CSRCS += sim_gpiochip.c
+
 ifeq ($(CONFIG_SIM_GPIOCHIP_LINUX),y)
   HOSTSRCS += sim_linux_gpiochip.c
-  CSRCS += sim_gpiochip.c
+endif
+
+ifeq ($(CONFIG_SIM_GPIOCHIP_FTDI),y)
+  HOSTSRCS += sim_ftdi_gpiochip.c
+  HOSTCFLAGS += $(shell pkg-config --cflags libftdi1)
+  STDLIBS += $(shell pkg-config --libs libftdi1)
+endif
 endif
 
 ifeq ($(CONFIG_SIM_USB_DEV),y)

arch/sim/src/sim/CMakeLists.txt

@@ -270,9 +270,22 @@ if(CONFIG_SIM_SPI_LINUX)
   list(APPEND HOSTSRCS sim_linuxspi.c)
 endif()
 
-if(CONFIG_SIM_GPIOCHIP_LINUX)
+if(CONFIG_SIM_GPIOCHIP)
   list(APPEND SRCS sim_gpiochip.c)
-  list(APPEND HOSTSRCS sim_linux_gpiochip.c)
+
+  if(CONFIG_SIM_GPIOCHIP_LINUX)
+    list(APPEND HOSTSRCS sim_linux_gpiochip.c)
+  endif()
+
+  if(CONFIG_SIM_GPIOCHIP_FTDI)
+    list(APPEND HOSTSRCS sim_ftdi_gpiochip.c)
+
+    find_package(PkgConfig REQUIRED)
+    pkg_check_modules(LIBFTDI1 REQUIRED IMPORTED_TARGET libftdi1)
+
+    list(APPEND HOST_INCLUDE_DIRECTORIES ${LIBFTDI1_INCLUDE_DIRS})
+    list(APPEND HOST_LINK_LIBRARIES PkgConfig::LIBFTDI1)
+  endif()
 endif()
 
 if(CONFIG_SIM_USB_DEV)