Merge #19880

19880: drivers/ft5x06: fix initialization if callback function parameter is NULL r=aabadie a=gschorcht

### Contribution description

This PR fixes the `ft5x06` driver initialization if the callback function parameter `cb` is `NULL. This might be the case for example if the application uses the touch device in polling mode.

If the interrupt pin is initialized if the callback function parameter `cb` is `NULL`, the driver crashes the first time an interrupt is triggered. Therefore, the INT pin must be initialized only if also the callback function parameter `cb` is not `NULL`.

To be able to test the polling mode, this PR also includes a change of the `tests/drivers/ft5x06` application which introduces the environment variables `FT5X06_POLLING_MODE` `FT5X06_POLLING_PERIOD` and in the makefile.

### Testing procedure

1. Use any board with a FTXXXX touch device and test it in polling mode, for example:
   ```
   FT5X06_POLLING_MODE=1 BOARD=stm32f746g-disco make -C tests/drivers/ft5x06 flash term
   ```
   It should work as expected.
   ```
   main(): This is RIOT! (Version: 2023.10-devel-119-g92a44a-drivers/ft5x06_fix_cb_null)
   FT5x06 test application
   +------------Initializing------------+
   Initialization successful
   1 touch detected
   Touch 1 - X: 236, Y:111
   Touch 1 - X: 236, Y:111
   ...
   Touch 1 - X: 236, Y:111
   Released!
   ```

2. Checkout master branch and cerry-pick commit 691a5e6308426ddc685e5a2c297238529211c258. The test application `tests/drivers/ft5x06` will crash once a touch event occur:
   ```
   +------------Initializing------------+
   Initialization successful
   1 touch detected
   Context before hardfault:
   ```

### Issues/PRs references

Co-authored-by: Gunar Schorcht <gunar@schorcht.net>

drivers/ft5x06/ft5x06.c

@@ -80,12 +80,13 @@ int ft5x06_init(ft5x06_t *dev, const ft5x06_params_t *params, ft5x06_event_cb_t
     }
 
     /* Configure interrupt */
-    if (gpio_is_valid(dev->params->int_pin)) {
+    if (gpio_is_valid(dev->params->int_pin) && cb) {
         DEBUG("[ft5x06] init: configuring touchscreen interrupt\n");
         gpio_init_int(dev->params->int_pin, GPIO_IN, GPIO_RISING, cb, arg);
-        i2c_write_reg(FT5X06_BUS, FT5X06_ADDR, FT5X06_G_MODE_REG, FT5X06_G_MODE_INTERRUPT_TRIGGER & 0x01, 0);
     }
 
+    i2c_write_reg(FT5X06_BUS, FT5X06_ADDR, FT5X06_G_MODE_REG, FT5X06_G_MODE_INTERRUPT_TRIGGER & 0x01, 0);
+
     i2c_release(FT5X06_BUS);
 
     return 0;

tests/drivers/ft5x06/Makefile

@@ -1,6 +1,16 @@
 BOARD ?= stm32f746g-disco
 include ../Makefile.drivers_common
 
+FT5X06_POLLING_MODE ?= 0
+FT5X06_POLLING_PERIOD ?= 50
+
+CFLAGS += -DFT5X06_POLLING_MODE=$(FT5X06_POLLING_MODE)
+CFLAGS += -DFT5X06_POLLING_PERIOD=$(FT5X06_POLLING_PERIOD)
+
 USEMODULE += ft5x06
 
+ifneq (0,$(FT5X06_POLLING_MODE))
+  USEMODULE += ztimer_msec
+endif
+
 include $(RIOTBASE)/Makefile.include

tests/drivers/ft5x06/README.md

@@ -0,0 +1,31 @@
+# About
+
+This is a manual test application for the FT5x06 touch device driver.
+
+# Usage
+
+The test application initializes the FT5x06 touch device and then waits
+for touch events by using interrupts by default. When touch events occur,
+the application generates output like the following:
+```
++------------Initializing------------+
+Initialization successful
+1 touch detected
+Touch 1 - X: 203, Y:156
+Touch 1 - X: 204, Y:157
+Touch 1 - X: 204, Y:157
+Touch 1 - X: 206, Y:158
+Touch 1 - X: 210, Y:159
+Touch 1 - X: 210, Y:159
+Touch 1 - X: 218, Y:160
+Released!
+```
+
+To use the touch device in polling mode, the environment variable
+`FT5X06_POLLING_MODE` must be set to 1. The polling period in milliseconds
+is defined by the environment variable `FT5X06_POLLING_PERIOD`. It is
+50 ms by default. It can be changed by setting the environment variable
+`FT5X06_POLLING_PERIOD` in the make command, for example:
+```
+FT5X06_POLLING_MODE=1 FT5X06_POLLING_PERIOD=100 BOARD=... make -C tests/drivers/touch_dev flash term
+```

tests/drivers/ft5x06/main.c

@@ -25,22 +25,39 @@
 #include "ft5x06.h"
 #include "ft5x06_params.h"
 
+#if IS_ACTIVE(FT5X06_POLLING_MODE)
+#include "ztimer.h"
+#endif
+
+#ifndef FT5X06_POLLING_PERIOD
+#define FT5X06_POLLING_PERIOD   50
+#endif
+
+#if !IS_ACTIVE(FT5X06_POLLING_MODE)
 static void _touch_event_cb(void *arg)
 {
     mutex_unlock(arg);
 }
+#endif
 
 static ft5x06_touch_position_t positions[FT5X06_TOUCHES_COUNT_MAX];
 
 int main(void)
 {
+#if !IS_ACTIVE(FT5X06_POLLING_MODE)
     mutex_t lock = MUTEX_INIT_LOCKED;
+#endif
+
     ft5x06_t dev;
 
     puts("FT5x06 test application\n");
 
     printf("+------------Initializing------------+\n");
+#if IS_ACTIVE(FT5X06_POLLING_MODE)
+    int ret = ft5x06_init(&dev, &ft5x06_params[0], NULL, NULL);
+#else
     int ret = ft5x06_init(&dev, &ft5x06_params[0], _touch_event_cb, &lock);
+#endif
     if (ret != 0) {
         puts("[Error] Initialization failed");
         return 1;
@@ -53,9 +70,13 @@ int main(void)
     uint8_t last_touch_count = current_touch_count;
 
     while (1) {
-
+#if IS_ACTIVE(FT5X06_POLLING_MODE)
+        /* polling is used */
+        ztimer_sleep(ZTIMER_MSEC, FT5X06_POLLING_PERIOD);
+#else
         /* wait for touch event */
         mutex_lock(&lock);
+#endif
 
         ft5x06_read_touch_count(&dev, &current_touch_count);