Kernel: Add support for the PS/2 mouse wheel if detected.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/dae8eb6454d

Kernel/Devices/PS2MouseDevice.cpp

@@ -10,6 +10,11 @@
 #define I8042_MOUSE_BUFFER       0x20
 #define I8042_KEYBOARD_BUFFER    0x00
 
+#define PS2MOUSE_GET_DEVICE_ID   0xF2
+#define PS2MOUSE_SET_SAMPLE_RATE 0xF3
+
+#define PS2MOUSE_INTELLIMOUSE_ID 0x03
+
 //#define PS2MOUSE_DEBUG
 
 static PS2MouseDevice* s_the;
@@ -40,6 +45,21 @@ void PS2MouseDevice::handle_irq()
 
         byte data = IO::in8(I8042_BUFFER);
         m_data[m_data_state] = data;
+
+        auto commit_packet = [&] {
+            m_data_state = 0;
+#ifdef PS2MOUSE_DEBUG
+            dbgprintf("PS2Mouse: %d, %d %s %s (buffered: %u)\n",
+                m_data[1],
+                m_data[2],
+                (m_data[0] & 1) ? "Left" : "",
+                (m_data[0] & 2) ? "Right" : "",
+                m_queue.size()
+            );
+#endif
+            parse_data_packet();
+        };
+
         switch (m_data_state) {
         case 0:
             if (!(data & 0x08)) {
@@ -52,17 +72,15 @@ void PS2MouseDevice::handle_irq()
             ++m_data_state;
             break;
         case 2:
-            m_data_state = 0;
-#ifdef PS2MOUSE_DEBUG
-            dbgprintf("PS2Mouse: %d, %d %s %s (buffered: %u)\n",
-                m_data[1],
-                m_data[2],
-                (m_data[0] & 1) ? "Left" : "",
-                (m_data[0] & 2) ? "Right" : "",
-                m_queue.size()
-            );
-#endif
-            parse_data_packet();
+            if (m_has_wheel) {
+                ++m_data_state;
+                break;
+            }
+            commit_packet();
+            break;
+        case 3:
+            ASSERT(m_has_wheel);
+            commit_packet();
             break;
         }
     }
@@ -72,6 +90,9 @@ void PS2MouseDevice::parse_data_packet()
 {
     int x = m_data[1];
     int y = m_data[2];
+    int z = 0;
+    if (m_has_wheel)
+        z = (char)m_data[3];
     bool x_overflow = m_data[0] & 0x40;
     bool y_overflow = m_data[0] & 0x80;
     bool x_sign = m_data[0] & 0x10;
@@ -87,7 +108,9 @@ void PS2MouseDevice::parse_data_packet()
     MousePacket packet;
     packet.dx = x;
     packet.dy = y;
+    packet.dz = z;
     packet.buttons = m_data[0] & 0x07;
+
     m_queue.enqueue(packet);
 }
 
@@ -119,17 +142,52 @@ void PS2MouseDevice::initialize()
 
     // Set default settings.
     mouse_write(0xf6);
-    byte ack1 = mouse_read();
-    ASSERT(ack1 == 0xfa);
+    expect_ack();
 
     // Enable.
     mouse_write(0xf4);
-    byte ack2 = mouse_read();
-    ASSERT(ack2 == 0xfa);
+    expect_ack();
+
+    mouse_write(PS2MOUSE_GET_DEVICE_ID);
+    expect_ack();
+    byte device_id = mouse_read();
+
+    if (device_id != PS2MOUSE_INTELLIMOUSE_ID) {
+        // Send magical wheel initiation sequence.
+        mouse_write(PS2MOUSE_SET_SAMPLE_RATE);
+        expect_ack();
+        mouse_write(200);
+        expect_ack();
+        mouse_write(PS2MOUSE_SET_SAMPLE_RATE);
+        expect_ack();
+        mouse_write(100);
+        expect_ack();
+        mouse_write(PS2MOUSE_SET_SAMPLE_RATE);
+        expect_ack();
+        mouse_write(80);
+        expect_ack();
+
+        mouse_write(PS2MOUSE_GET_DEVICE_ID);
+        expect_ack();
+        device_id = mouse_read();
+    }
+
+    if (device_id == PS2MOUSE_INTELLIMOUSE_ID) {
+        m_has_wheel = true;
+        kprintf("PS2MouseDevice: Mouse wheel enabled!\n");
+    } else {
+        kprintf("PS2MouseDevice: No mouse wheel detected!\n");
+    }
 
     enable_irq();
 }
 
+void PS2MouseDevice::expect_ack()
+{
+    byte data = mouse_read();
+    ASSERT(data == I8042_ACK);
+}
+
 void PS2MouseDevice::prepare_for_input()
 {
     for (;;) {

Kernel/Devices/PS2MouseDevice.h

@@ -33,8 +33,10 @@ private:
     void wait_then_write(byte port, byte data);
     byte wait_then_read(byte port);
     void parse_data_packet();
+    void expect_ack();
 
     CircularQueue<MousePacket, 100> m_queue;
     byte m_data_state { 0 };
-    byte m_data[3];
+    byte m_data[4];
+    bool m_has_wheel { false };
 };

Kernel/MousePacket.h

@@ -3,5 +3,6 @@
 struct MousePacket {
     int dx { 0 };
     int dy { 0 };
-    byte buttons;
+    int dz { 0 };
+    byte buttons { 0 };
 };