Rewrite kobo color inputs

meson.build

@@ -2,5 +2,5 @@ project('kobo-color-inputdev', 'c',
   version : '0.1',
   default_options : ['warning_level=3'])
 
-exe = executable('kobo-color-inputdev', 'src/main.c',
+main = executable('kobo-color-inputdev', ['src/main.c', './src/device.c'],
   install : true)

shell.nix

@@ -1,5 +1,5 @@
 { pkgs ? import <nixpkgs> { } }:
 pkgs.mkShell {
-  packages = with pkgs; [ libevent clang-tools ];
+  packages = with pkgs; [ libinput evtest clang-tools ];
   inputsFrom = [ (pkgs.callPackage ./default.nix { }) ];
 }

src/device.c

@@ -0,0 +1,102 @@
+#include "logger.h"
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/input-event-codes.h>
+#include <linux/input.h>
+#include <linux/uinput.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+struct uinput_abs_setup ABS_SETUP_X = {.code = ABS_X,
+                                       .absinfo = {
+                                           0,
+                                           .maximum = 1680,
+                                           .resolution = 6,
+                                       }};
+
+struct uinput_abs_setup ABS_SETUP_Y = {.code = ABS_Y,
+                                       .absinfo = {
+                                           0,
+                                           .maximum = 1264,
+                                           .resolution = 8,
+                                       }};
+
+struct uinput_abs_setup ABS_SETUP_PRESSURE = {.code = ABS_PRESSURE,
+                                              .absinfo = {
+                                                  0,
+                                                  .maximum = 4095,
+                                              }};
+
+struct uinput_abs_setup ABS_SETUP_TILT_X = {.code = ABS_TILT_X,
+                                            .absinfo = {
+                                                0,
+                                                .minimum = -60,
+                                                .maximum = 60,
+                                            }};
+
+struct uinput_abs_setup ABS_SETUP_TILT_Y = {.code = ABS_TILT_Y,
+                                            .absinfo = {
+                                                0,
+                                                .minimum = -60,
+                                                .maximum = 60,
+                                            }};
+
+struct uinput_abs_setup ABS_SETUP_DISTANCE = {.code = ABS_DISTANCE,
+                                              .absinfo = {
+                                                  0,
+                                                  .maximum = 0xf,
+                                              }};
+
+int setup(FILE **device) {
+  struct uinput_setup usetup;
+  int fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
+  if (fd < 0) {
+    char *error = strerror(errno);
+    logf("Error opening /dev/uinput: %s", error);
+    return 1;
+  }
+
+  /*
+   * The ioctls below will enable the device that is about to be
+   * created, to pass key events, in this case the space key.
+   */
+  ioctl(fd, UI_SET_EVBIT, EV_SYN);
+  ioctl(fd, UI_SET_EVBIT, EV_KEY);
+  ioctl(fd, UI_SET_EVBIT, EV_ABS);
+
+  ioctl(fd, UI_ABS_SETUP, &ABS_SETUP_X);
+  ioctl(fd, UI_ABS_SETUP, &ABS_SETUP_Y);
+  ioctl(fd, UI_ABS_SETUP, &ABS_SETUP_PRESSURE);
+  ioctl(fd, UI_ABS_SETUP, &ABS_SETUP_TILT_X);
+  ioctl(fd, UI_ABS_SETUP, &ABS_SETUP_TILT_Y);
+  ioctl(fd, UI_ABS_SETUP, &ABS_SETUP_DISTANCE);
+
+  ioctl(fd, UI_SET_KEYBIT, BTN_TOUCH);
+  ioctl(fd, UI_SET_KEYBIT, BTN_STYLUS);
+  ioctl(fd, UI_SET_KEYBIT, BTN_STYLUS2);
+
+  memset(&usetup, 0, sizeof(usetup));
+  usetup.id.bustype = BUS_VIRTUAL;
+  usetup.id.vendor = 0x1234;  /* sample vendor */
+  usetup.id.product = 0x5678; /* sample product */
+  strcpy(usetup.name, "Elan Touchscreen");
+
+  ioctl(fd, UI_DEV_SETUP, &usetup);
+  ioctl(fd, UI_DEV_CREATE);
+
+  FILE *file = fdopen(fd, "w");
+  *device = file;
+
+  return 0;
+}
+
+void cleanup(FILE *device) {
+  fflush(device);
+
+  ioctl(fileno(device), UI_DEV_DESTROY);
+
+  fclose(device);
+}

src/device.h

@@ -0,0 +1,5 @@
+#pragma once
+#include <stdio.h>
+
+int setup(FILE **dev);
+int cleanup(FILE *dev);

src/logger.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#define BLK "\x1B[0;30m"
+#define RED "\x1B[0;31m"
+#define GRN "\x1B[0;32m"
+#define YEL "\x1B[0;33m"
+#define BLU "\x1B[0;34m"
+#define MAG "\x1B[0;35m"
+#define CYN "\x1B[0;36m"
+#define WHT "\x1B[0;37m"
+#define RESET "\x1B[0m"
+
+#define logf(x, ...)                                                           \
+  fprintf(stderr, "%s%s%s:%s%d%s: " x "\n", BLU, __FILE_NAME__, WHT, RED,      \
+          __LINE__, RESET, __VA_ARGS__);
+
+#define log(x) logf("%s", x)

src/main.c

@@ -1,12 +1,166 @@
+#include "device.h"
+#include "logger.h"
+#include <assert.h>
+#include <linux/input-event-codes.h>
+#include <linux/input.h>
+#include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
-#define PROJECT_NAME "kobo-color-inputdev"
+int read_input_event(struct input_event *ie) {
+  if (fread(ie, sizeof(struct input_event), 1, stdin) != 1) {
+    if (feof(stdin)) {
+      return EOF;
+    } else {
+      char *err = strerror(ferror(stdin));
+      logf("Error reading input event! %s", err);
 
-int main(int argc, char **argv) {
-    if(argc != 1) {
-        printf("%s takes no arguments.\n", argv[0]);
       return 1;
     }
-    printf("This is project %s.\n", PROJECT_NAME);
+  }
   return 0;
 }
+
+int read_to_match(struct input_event *ie, int type, int code, int value) {
+  int res;
+  while (!(res = read_input_event(ie) && (type == ie->type) &&
+                 (code == -1 || code == ie->code) &&
+                 (value == -1 || value == ie->value))) {
+  };
+  return res;
+}
+
+int forward_event(FILE *dev, struct input_event *ie) {
+  if (fwrite(ie, sizeof(struct input_event), 1, dev) != 1) {
+    if (feof(dev)) {
+      return EOF;
+    } else {
+      char *err = strerror(ferror(dev));
+      logf("Error writing input event(type: %x, code: %x, value: %x)! %s",
+           ie->type, ie->code, ie->value, err);
+
+      return 1;
+    }
+  }
+  if (ie->type == EV_SYN) {
+    fflush(dev);
+  }
+  return 0;
+}
+
+bool rewrite_abs_pen_event(struct input_event *ie) {
+  assert(ie->type == EV_ABS);
+
+  switch (ie->code) {
+  // Rewrite the event codes
+  case ABS_MT_POSITION_X:
+    ie->code = ABS_X;
+    break;
+  case ABS_MT_POSITION_Y:
+    ie->code = ABS_Y;
+    break;
+  case ABS_MT_PRESSURE:
+    ie->code = ABS_PRESSURE;
+    break;
+  case ABS_MT_DISTANCE:
+    ie->code = ABS_DISTANCE;
+  // Passthrough events:
+  case ABS_TILT_X:
+  case ABS_TILT_Y:
+    break;
+  // Ignore events without logging
+  case ABS_MT_TRACKING_ID:
+  case ABS_MT_TOOL_TYPE:
+  case ABS_MT_TOUCH_MAJOR:
+  case ABS_MT_TOUCH_MINOR:
+  // Custom kobo event codes, extracted from headers at:
+  // https://github.com/kobolabs/Kobo-Reader/blob/master/hw/mt8113-libraC_vision7/
+  // ABS_AZIMUTH
+  case 0x1d:
+  // ABS_TIP_MIN
+  case 0x2a:
+  // ABS_TIP_MAX
+  case 0x29:
+    return false;
+  default:
+    logf("Unknown EV_ABS! code: %x, value: %x", ie->code, ie->value);
+    return false;
+  }
+  return true;
+}
+
+int rewrite_key_pen_event(struct input_event *ie) {
+  assert(ie->type == EV_KEY);
+  switch (ie->code) {
+  case BTN_TOUCH:
+  case BTN_STYLUS:
+  case BTN_STYLUS2:
+    return true;
+  // Known events we don't want to forward
+  case KEY_BATTERY:
+    return false;
+  // Uknown events
+  default:
+    logf("Unknown EV_KEY! code: %x, value: %x", ie->code, ie->value);
+    return false;
+  }
+  return 0;
+}
+
+int rewrite_syn_pen_event(struct input_event *ie) {
+  assert(ie->type == EV_SYN);
+  if (ie->code == SYN_MT_REPORT)
+    ie->code = SYN_REPORT;
+
+  return true;
+}
+
+bool rewrite_pen_event(struct input_event *ie) {
+  switch (ie->type) {
+  case EV_ABS:
+    return rewrite_abs_pen_event(ie);
+  case EV_KEY:
+    return rewrite_key_pen_event(ie);
+  case EV_SYN:
+    return rewrite_syn_pen_event(ie);
+  default:
+    break;
+  }
+  return false;
+}
+
+int process_events(FILE *dev) {
+  while (true) {
+    int res;
+    struct input_event ie;
+    while ((!(res = read_input_event(&ie))) &&
+           (ie.type != EV_ABS && (ie.code != ABS_MT_TOOL_TYPE) &&
+            (ie.value != MT_TOOL_PEN))) {
+    }
+    if (res == EOF)
+      return EXIT_SUCCESS;
+    if (res != 0)
+      return EXIT_FAILURE;
+
+    while (!(res = read_input_event(&ie) && (ie.type == EV_ABS) &&
+                   (ie.code == ABS_MT_TOOL_TYPE) &&
+                   (ie.value != MT_TOOL_PEN))) {
+      if (rewrite_pen_event(&ie))
+        forward_event(dev, &ie);
+    };
+    if (res != 0)
+      return EXIT_FAILURE;
+  }
+}
+
+int main(void) {
+  FILE *dev;
+  int res = setup(&dev);
+  if (res) {
+    return EXIT_FAILURE;
+  }
+  res = process_events(dev);
+  cleanup(dev);
+  return EXIT_SUCCESS;
+}