Add support for the XPT2046 touchscreen controller on the Viewtool LCD module

8 files changed, 447 insertions, 40 deletions

diff --git a/apps/nshlib/Kconfig b/apps/nshlib/Kconfig
index 7953cf681..19216ecb3 100644
--- a/apps/nshlib/Kconfig
+++ b/apps/nshlib/Kconfig
@@ -12,6 +12,7 @@ config NSH_LIBRARY
 		in order to implement the full NuttShell (NSH).
 
 if NSH_LIBRARY
+
 config NSH_BUILTIN_APPS
 	bool "Enable built-in applications"
 	default n
@@ -320,7 +321,7 @@ config NSH_ROMFSETC
 		at /etc/init.d/rcS.  The default startup script will mount
 		a FAT FS RAMDISK at /tmp but the logic is easily extensible.
 
-endif
+endif # NSH_LIBRARY
 
 if NSH_ROMFSETC
 
@@ -380,7 +381,6 @@ config NSH_ROMFSSECTSIZE
 config NSH_ARCHROMFS
 	bool "Architecture-specific ROMFS header"
 	default n
-	depends on NSH_ROMFSETC
 	---help---
 		Enable this option to provide an architecture-specific ROMFS
 		header at <arch/board/nsh_romfsimg.h>. Note that this header
@@ -424,9 +424,10 @@ config NSH_FATMOUNTPT
 		will mount a FAT FS under /tmp. This is the location where the FAT
 		FS will be mounted.  Default is "/tmp".
 
-endif
+endif # NSH_ROMFSETC
 
 if NSH_LIBRARY
+
 config NSH_CONSOLE
 	bool "Use console"
 	default y
@@ -478,6 +479,7 @@ config USBDEV_MINOR
 		minor number may also need to be provided. Default: 0
 
 comment "USB Trace Support"
+
 config NSH_USBDEV_TRACE
 	bool "Enable Builtin USB Trace Support"
 	default n
@@ -524,7 +526,7 @@ config NSH_USBDEV_TRACEINTERRUPTS
 	---help---
 		Show interrupt-related events
 
-endif
+endif # NSH_USBDEV_TRACE
 
 config NSH_CONDEV
 	bool "Default console device"
@@ -565,7 +567,7 @@ config NSH_TELNET
 		you may log into NuttX remotely using telnet in order to
 		access NSH.
 
-endif
+endif # NSH_LIBRARY
 
 if NSH_TELNET
 
@@ -634,8 +636,8 @@ config NSH_TELNET_FAILCOUNT
 	---help---
 		Number of login retry attempts.
 
-endif
-endif
+endif # NSH_TELNET_LOGIN
+endif # NSH_TELNET
 
 config NSH_DHCPC
 	bool "Use DHCP to get IP address"
@@ -702,4 +704,3 @@ config NSH_MAX_ROUNDTRIP
 	---help---
 		This is the maximum round trip for a response to a ICMP ECHO request.
 		It is in units of deciseconds.  The default is 20 (2 seconds).
-
diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 62fed73d4..4c250d28e 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -6404,4 +6404,8 @@
 	  nx_open.c, and nx_openwindow.c:  Needs to use kuzalloc and kufree,
 	  not umm_zalloc and umm_free.  Additional typo in nx_constructwindow.c
 	  (wnd should be hwnd). Also noted by Steve Redler IV (2014-1-7).
+	* configs/viewtool-stm32f107/src/stm32_touchscreen.c (and other
+	  files):  Add support for the XPT2046 touchscreen controller on
+	  the Viewtool LCD module connected to the Viewtool STM32F103
+	  board (2014-1-9).
 
diff --git a/nuttx/arch/arm/src/stm32/stm32_spi.h b/nuttx/arch/arm/src/stm32/stm32_spi.h
index e40db48dd..62f304dfb 100644
--- a/nuttx/arch/arm/src/stm32/stm32_spi.h
+++ b/nuttx/arch/arm/src/stm32/stm32_spi.h
@@ -54,7 +54,8 @@
 #undef EXTERN
 #if defined(__cplusplus)
 #define EXTERN extern "C"
-extern "C" {
+extern "C"
+{
 #else
 #define EXTERN extern
 #endif
@@ -99,29 +100,41 @@ enum    spi_dev_e;
  *
  ************************************************************************************/
 
-EXTERN void  stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
-EXTERN uint8_t stm32_spi1status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
-EXTERN int stm32_spi1cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#ifdef CONFIG_STM32_SPI1
+void stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+uint8_t stm32_spi1status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+int stm32_spi1cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
 
-EXTERN void  stm32_spi2select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
-EXTERN uint8_t stm32_spi2status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
-EXTERN int stm32_spi2cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#ifdef CONFIG_STM32_SPI2
+void stm32_spi2select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+uint8_t stm32_spi2status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+int stm32_spi2cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
 
-EXTERN void  stm32_spi3select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
-EXTERN uint8_t stm32_spi3status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
-EXTERN int stm32_spi3cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#ifdef CONFIG_STM32_SPI3
+void stm32_spi3select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+uint8_t stm32_spi3status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+int stm32_spi3cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
 
-EXTERN void  stm32_spi4select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
-EXTERN uint8_t stm32_spi4status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
-EXTERN int stm32_spi4cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#ifdef CONFIG_STM32_SPI4
+void stm32_spi4select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+uint8_t stm32_spi4status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+int stm32_spi4cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
 
-EXTERN void  stm32_spi5select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
-EXTERN uint8_t stm32_spi5status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
-EXTERN int stm32_spi5cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#ifdef CONFIG_STM32_SPI5
+void stm32_spi5select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+uint8_t stm32_spi5status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+int stm32_spi5cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
 
-EXTERN void  stm32_spi6select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
-EXTERN uint8_t stm32_spi6status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
-EXTERN int stm32_spi6cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#ifdef CONFIG_STM32_SPI6
+void stm32_spi6select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+uint8_t stm32_spi6status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+int stm32_spi6cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
 
 #undef EXTERN
 #if defined(__cplusplus)
diff --git a/nuttx/configs/viewtool-stm32f107/README.txt b/nuttx/configs/viewtool-stm32f107/README.txt
index f339aadce..d55bdf924 100644
--- a/nuttx/configs/viewtool-stm32f107/README.txt
+++ b/nuttx/configs/viewtool-stm32f107/README.txt
@@ -28,7 +28,7 @@ Contents
   o USB Interface
   o microSD Card Interface
   o ViewTool DP83848 Ethernet Module
-  o LCD Interface
+  o LCD/Touchscreen Interface
   o Toolchains
     - NOTE about Windows native toolchains
   o Configurations
@@ -397,8 +397,8 @@ ViewTool DP83848 Ethernet Module
       (also FTP, TFTP, WGET, NFS, etc. if you also have a mass storage
       device).
 
-LCD Interface
-=============
+LCD/Touchscreen Interface
+=========================
 
   An LCD may be connected via J11.  Only the the STM32F103 supports the FSMC signals
   needed to drive the LCD.
@@ -650,6 +650,53 @@ Configurations
     4. USB support is disabled by default.  See the section above entitled,
        "USB Interface"
 
+    5. This configuration has been used for verifying the touchscreen on
+       on the Viewtool LCD module.  NOTE:  The LCD module can really only
+       be used on the STM32F103 version of the board.  The LCD requires
+       FSMC support (the touchscreen, however, does not but the touchscreen
+       is not very meaningful with no LCD).
+
+         CONFIG_ARCH_CHIP_STM32F103VCT6=y      : Select STM32F103VCT6
+
+       With the following modifications, you can include the touchscreen
+       test program at apps/examples/touchscreen as an NSH built-in
+       application.  You can enable the touchscreen and test by modifying
+       the default configuration in the following ways:
+
+          Device Drivers
+            CONFIG_SPI=y                       : Enable SPI support
+            CONFIG_SPI_EXCHANGE=y              : The exchange() method is supported
+            CONFIG_SPI_OWNBUS=y                : Smaller code if this is the only SPI device
+
+            CONFIG_INPUT=y                     : Enable support for input devices
+            CONFIG_INPUT_ADS7843E=y            : Enable support for the XPT2046
+            CONFIG_ADS7843E_SPIDEV=2           : Use SPI2 for communication
+            CONFIG_ADS7843E_SPIMODE=0          : Use SPI mode 0
+            CONFIG_ADS7843E_FREQUENCY=1000000  : SPI BAUD 1MHz
+            CONFIG_ADS7843E_SWAPXY=y           : If landscape orientation
+            CONFIG_ADS7843E_THRESHX=51         : These will probably need to be tuned
+            CONFIG_ADS7843E_THRESHY=39
+
+          System Type -> Peripherals:
+            CONFIG_STM32_SPI2=y                : Enable support for SPI2
+
+          RTOS Features:
+            CONFIG_DISABLE_SIGNALS=n           : Signals are required
+
+          Library Support:
+            CONFIG_SCHED_WORKQUEUE=y           : Work queue support required
+
+          Applicaton Configuration:
+            CONFIG_EXAMPLES_TOUCHSCREEN=y      : Enable the touchscreen built-int test
+
+          Defaults should be okay for related touchscreen settings.  Touchscreen
+          debug output on USART1 can be enabled with:
+
+          Build Setup:
+            CONFIG_DEBUG=y                     : Enable debug features
+            CONFIG_DEBUG_VERBOSE=y             : Enable verbose debug output
+            CONFIG_DEBUG_INPUT=y               : Enable debug output from input devices
+
   highpri:
 
     This configuration was used to verify the NuttX high priority, nested
diff --git a/nuttx/configs/viewtool-stm32f107/nsh/defconfig b/nuttx/configs/viewtool-stm32f107/nsh/defconfig
index b09764e6b..bd00df156 100644
--- a/nuttx/configs/viewtool-stm32f107/nsh/defconfig
+++ b/nuttx/configs/viewtool-stm32f107/nsh/defconfig
@@ -211,6 +211,8 @@ CONFIG_STM32_CONNECTIVITYLINE=y
 #
 # STM32 Peripheral Support
 #
+# CONFIG_STM32_HAVE_USBDEV is not set
+CONFIG_STM32_HAVE_OTGFS=y
 # CONFIG_STM32_ADC1 is not set
 # CONFIG_STM32_ADC2 is not set
 # CONFIG_STM32_ADC3 is not set
@@ -224,6 +226,7 @@ CONFIG_STM32_CONNECTIVITYLINE=y
 # CONFIG_STM32_ETHMAC is not set
 # CONFIG_STM32_I2C1 is not set
 # CONFIG_STM32_I2C2 is not set
+# CONFIG_STM32_OTGFS is not set
 CONFIG_STM32_PWR=y
 # CONFIG_STM32_SPI1 is not set
 # CONFIG_STM32_SPI2 is not set
@@ -241,7 +244,6 @@ CONFIG_STM32_USART1=y
 # CONFIG_STM32_USART3 is not set
 # CONFIG_STM32_UART4 is not set
 # CONFIG_STM32_UART5 is not set
-# CONFIG_STM32_USB is not set
 # CONFIG_STM32_IWDG is not set
 # CONFIG_STM32_WWDG is not set
 
@@ -667,16 +669,11 @@ CONFIG_EXAMPLES_NSH=y
 # Networking Utilities
 #
 # CONFIG_NETUTILS_CODECS is not set
-# CONFIG_NETUTILS_DHCPC is not set
 # CONFIG_NETUTILS_DHCPD is not set
 # CONFIG_NETUTILS_FTPC is not set
 # CONFIG_NETUTILS_FTPD is not set
 # CONFIG_NETUTILS_JSON is not set
-CONFIG_NETUTILS_RESOLV=y
-CONFIG_NET_RESOLV_ENTRIES=8
-CONFIG_NET_RESOLV_MAXRESPONSE=96
 # CONFIG_NETUTILS_SMTP is not set
-# CONFIG_NETUTILS_TELNETD is not set
 CONFIG_NETUTILS_TFTPC=y
 # CONFIG_NETUTILS_THTTPD is not set
 CONFIG_NETUTILS_UIPLIB=y
diff --git a/nuttx/configs/viewtool-stm32f107/src/Makefile b/nuttx/configs/viewtool-stm32f107/src/Makefile
index 6c4c57b0b..f5f5cf1a4 100644
--- a/nuttx/configs/viewtool-stm32f107/src/Makefile
+++ b/nuttx/configs/viewtool-stm32f107/src/Makefile
@@ -62,6 +62,10 @@ CSRCS += stm32_usbdev.c
 endif
 endif
 
+ifeq ($(CONFIG_INPUT_ADS7843E),y) # F103
+CSRCS += stm32_touchscreen.c
+endif
+
 ifeq ($(CONFIG_LCD_SSD1289),y) # F103
 CSRCS += stm32_ssd1289.c
 endif
diff --git a/nuttx/configs/viewtool-stm32f107/src/stm32_spi.c b/nuttx/configs/viewtool-stm32f107/src/stm32_spi.c
index 38f4acd81..5ac136b3f 100644
--- a/nuttx/configs/viewtool-stm32f107/src/stm32_spi.c
+++ b/nuttx/configs/viewtool-stm32f107/src/stm32_spi.c
@@ -87,7 +87,8 @@
  * Name: stm32_spiinitialize
  *
  * Description:
- *   Called to configure SPI chip select GPIO pins for the Viewtools stm32f103/107 board.
+ *   Called to configure SPI chip select GPIO pins for the Viewtool stm32f103/107
+ *   board.
  *
  ************************************************************************************/
 
@@ -98,6 +99,12 @@ void weak_function stm32_spiinitialize(void)
    *       Here, we only initialize chip select pins unique to the board
    *       architecture.
    */
+
+#if defined(CONFIG_STM32_SPI2) && defined(CONFIG_INPUT_ADS7843E)
+  /* Configure the XPT2046 SPI2 CS pin as an output */
+
+  (void)stm32_configgpio(GPIO_LCDTP_CS);
+#endif
 }
 
 /****************************************************************************
@@ -141,6 +148,15 @@ uint8_t stm32_spi1status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
 void stm32_spi2select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected)
 {
   spidbg("devid: %d CS: %s\n", (int)devid, selected ? "assert" : "de-assert");
+
+#ifdef CONFIG_INPUT_ADS7843E
+  /* Select/de-select the touchscreen */
+
+  if (devid == SPIDEV_TOUCHSCREEN)
+    {
+      stm32_gpiowrite(GPIO_LCDTP_CS, !selected);
+    }
+#endif
 }
 
 uint8_t stm32_spi2status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
@@ -149,13 +165,13 @@ uint8_t stm32_spi2status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
 }
 #endif
 
-#ifdef CONFIG_STM32_SPI2
-void stm32_spi2select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected)
+#ifdef CONFIG_STM32_SPI3
+void stm32_spi3select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected)
 {
   spidbg("devid: %d CS: %s\n", (int)devid, selected ? "assert" : "de-assert");
 }
 
-uint8_t stm32_spi2status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
+uint8_t stm32_spi3status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
 {
   return 0;
 }
diff --git a/nuttx/configs/viewtool-stm32f107/src/stm32_touchscreen.c b/nuttx/configs/viewtool-stm32f107/src/stm32_touchscreen.c
new file mode 100644
index 000000000..e2061e469
--- /dev/null
+++ b/nuttx/configs/viewtool-stm32f107/src/stm32_touchscreen.c
@@ -0,0 +1,325 @@
+/************************************************************************************
+ * configs/viewtools-stm32f107/src/stm32_touchscreen.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <stdbool.h>
+#include <stdio.h>
+#include <debug.h>
+#include <assert.h>
+#include <errno.h>
+
+#include <nuttx/spi/spi.h>
+#include <nuttx/input/touchscreen.h>
+#include <nuttx/input/ads7843e.h>
+
+#include "up_arch.h"
+#include "stm32_gpio.h"
+
+#include "viewtool_stm32f107.h"
+
+#ifdef CONFIG_INPUT_ADS7843E
+
+/****************************************************************************
+ * Pre-Processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************/
+
+#ifndef CONFIG_STM32_SPI2
+#  error CONFIG_STM32_SPI2 is required for touchscreen support
+#endif
+
+#ifndef CONFIG_ADS7843E_FREQUENCY
+#  define CONFIG_ADS7843E_FREQUENCY 500000
+#endif
+
+#ifndef CONFIG_ADS7843E_DEVMINOR
+#  define CONFIG_ADS7843E_DEVMINOR 0
+#endif
+
+/* The touchscreen communicates on SPI2 */
+
+#define TSC_DEVNUM 2
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct viewtool_tscinfo_s
+{
+  /* Standard ADS7843/XTP2046 interface */
+
+  struct ads7843e_config_s config;
+
+  /* Extensions for the viewtool board */
+
+  xcpt_t handler;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* IRQ/GPIO access callbacks.  These operations all hidden behind
+ * callbacks to isolate the XPT2046 driver from differences in GPIO
+ * interrupt handling by varying boards and MCUs.  If possible,
+ * interrupts should be configured on both rising and falling edges
+ * so that contact and loss-of-contact events can be detected.
+ *
+ *   attach  - Attach the XPT2046 interrupt handler to the GPIO interrupt
+ *   enable  - Enable or disable the GPIO interrupt
+ *   clear   - Acknowledge/clear any pending GPIO interrupt
+ *   pendown - Return the state of the pen down GPIO input
+ */
+
+static int  tsc_attach(FAR struct ads7843e_config_s *state, xcpt_t isr);
+static void tsc_enable(FAR struct ads7843e_config_s *state, bool enable);
+static void tsc_clear(FAR struct ads7843e_config_s *state);
+static bool tsc_busy(FAR struct ads7843e_config_s *state);
+static bool tsc_pendown(FAR struct ads7843e_config_s *state);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* A reference to a structure of this type must be passed to the XPT2046
+ * driver.  This structure provides information about the configuration
+ * of the XPT2046 and provides some board-specific hooks.
+ *
+ * Memory for this structure is provided by the caller.  It is not copied
+ * by the driver and is presumed to persist while the driver is active. The
+ * memory must be writable because, under certain circumstances, the driver
+ * may modify certain values.
+ */
+
+static struct viewtool_tscinfo_s g_tscinfo =
+{
+  .config =
+  {
+    .frequency = CONFIG_ADS7843E_FREQUENCY,
+
+    .attach    = tsc_attach,
+    .enable    = tsc_enable,
+    .clear     = tsc_clear,
+    .busy      = tsc_busy,
+    .pendown   = tsc_pendown,
+  },
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * IRQ/GPIO access callbacks.  These operations all hidden behind
+ * callbacks to isolate the XPT2046 driver from differences in GPIO
+ * interrupt handling by varying boards and MCUs.  If possible,
+ * interrupts should be configured on both rising and falling edges
+ * so that contact and loss-of-contact events can be detected.
+ *
+ *   attach  - Attach the XPT2046 interrupt handler to the GPIO interrupt
+ *   enable  - Enable or disable the GPIO interrupt
+ *   clear   - Acknowledge/clear any pending GPIO interrupt
+ *   pendown - Return the state of the pen down GPIO input
+ *
+ ****************************************************************************/
+
+static int tsc_attach(FAR struct ads7843e_config_s *state, xcpt_t isr)
+{
+  FAR struct viewtool_tscinfo_s *priv = (FAR struct viewtool_tscinfo_s *)state;
+
+  if (isr)
+    {
+      /* Just save the address of the handler for now.  The new handler will
+       * be attached when the interrupt is next enabled.
+       */
+
+      ivdbg("Attaching %p\n", isr);
+      priv->handler = isr;
+    }
+  else
+    {
+      ivdbg("Detaching %p\n", priv->handler);
+      tsc_enable(state, false);
+      priv->handler = NULL;
+    }
+
+  return OK;
+}
+
+static void tsc_enable(FAR struct ads7843e_config_s *state, bool enable)
+{
+  FAR struct viewtool_tscinfo_s *priv = (FAR struct viewtool_tscinfo_s *)state;
+  irqstate_t flags;
+
+  /* Attach and enable, or detach and disable.  Enabling and disabling GPIO
+   * interrupts is a multi-step process so the safest thing is to keep
+   * interrupts disabled during the reconfiguration.
+   */
+
+  flags = irqsave();
+  if (enable && priv->handler)
+    {
+      /* Configure the EXTI interrupt using the SAVED handler */
+
+      (void)stm32_gpiosetevent(GPIO_LCDTP_IRQ, true, true, true, priv->handler);
+    }
+  else
+    {
+      /* Configure the EXTI interrupt with a NULL handler to disable it */
+
+     (void)stm32_gpiosetevent(GPIO_LCDTP_IRQ, false, false, false, NULL);
+    }
+
+  irqrestore(flags);
+}
+
+static void tsc_clear(FAR struct ads7843e_config_s *state)
+{
+  /* Does nothing */
+}
+
+static bool tsc_busy(FAR struct ads7843e_config_s *state)
+{
+  return false; /* The BUSY signal is not connected */
+}
+
+static bool tsc_pendown(FAR struct ads7843e_config_s *state)
+{
+  /* The /PENIRQ value is active low */
+
+  bool pendown = !stm32_gpioread(GPIO_LCDTP_IRQ);
+  ivdbg("pendown=%d\n", pendown);
+  return pendown;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: arch_tcinitialize
+ *
+ * Description:
+ *   Each board that supports a touchscreen device must provide this function.
+ *   This function is called by application-specific, setup logic to
+ *   configure the touchscreen device.  This function will register the driver
+ *   as /dev/inputN where N is the minor device number.
+ *
+ * Input Parameters:
+ *   minor   - The input device minor number
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int arch_tcinitialize(int minor)
+{
+  FAR struct spi_dev_s *dev;
+  static bool initialized = false;
+  int ret;
+
+  idbg("minor %d\n", minor);
+  DEBUGASSERT(minor == 0);
+
+  /* Have we already initialized?  Since we never uninitialize we must prevent
+   * multiple initializations.  This is necessary, for example, when the
+   * touchscreen example is used as a built-in application in NSH and can be
+   * called numerous time.  It will attempt to initialize each time.
+   */
+
+  if (!initialized)
+    {
+      /* Configure the XPT2046 interrupt pin as an input */
+
+      (void)stm32_configgpio(GPIO_LCDTP_IRQ);
+
+      /* Get an instance of the SPI interface for the touchscreen chip select */
+
+      dev = up_spiinitialize(TSC_DEVNUM);
+      if (!dev)
+        {
+          idbg("Failed to initialize SPI%d\n", TSC_DEVNUM);
+          return -ENODEV;
+        }
+
+      /* Initialize and register the SPI touchscreen device */
+
+      ret = ads7843e_register(dev, &g_tscinfo.config, CONFIG_ADS7843E_DEVMINOR);
+      if (ret < 0)
+        {
+          idbg("Failed to register touchscreen device\n");
+          /* up_spiuninitialize(dev); */
+          return -ENODEV;
+        }
+
+      /* Now we are initialized */
+
+      initialized = true;
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: arch_tcuninitialize
+ *
+ * Description:
+ *   Each board that supports a touchscreen device must provide this function.
+ *   This function is called by application-specific, setup logic to
+ *   uninitialize the touchscreen device.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void arch_tcuninitialize(void)
+{
+  /* No support for un-initializing the touchscreen XPT2046 device.  It will
+   * continue to run and process touch interrupts in the background.
+   */
+}
+
+#endif /* CONFIG_INPUT_ADS7843E */