Merge branch 'ps2_mouse_fix'

6 files changed, 257 insertions, 214 deletions

diff --git a/protocol/lufa/lufa.c b/protocol/lufa/lufa.c
index a230d5ba2..04e8e78f3 100644
--- a/protocol/lufa/lufa.c
+++ b/protocol/lufa/lufa.c
@@ -539,11 +539,18 @@ int main(void)
 {
     SetupHardware();
     sei();
+
+    /* wait for USB startup & debug output */
+    while (USB_DeviceState != DEVICE_STATE_Configured) {
 #if defined(INTERRUPT_CONTROL_ENDPOINT)
-    while (USB_DeviceState != DEVICE_STATE_Configured) ;
+        ;
+#else
+        USB_USBTask();
 #endif
+    }
     print("USB configured.\n");
 
+    /* init modules */
     keyboard_init();
     host_set_driver(&lufa_driver);
 #ifdef SLEEP_LED_ENABLE
diff --git a/protocol/pjrc.mk b/protocol/pjrc.mk
index 27f908b1c..5a4461382 100644
--- a/protocol/pjrc.mk
+++ b/protocol/pjrc.mk
@@ -7,7 +7,11 @@ SRC +=	$(PJRC_DIR)/main.c \
         $(PJRC_DIR)/usb.c
 
 # Option modules
-ifdef $(or MOUSEKEY_ENABLE, PS2_MOUSE_ENABLE)
+ifdef MOUSEKEY_ENABLE
+    SRC += $(PJRC_DIR)/usb_mouse.c
+endif
+
+ifdef PS2_MOUSE_ENABLE
     SRC += $(PJRC_DIR)/usb_mouse.c
 endif
 
diff --git a/protocol/ps2.c b/protocol/ps2.c
index ed4560910..e5873a9bf 100644
--- a/protocol/ps2.c
+++ b/protocol/ps2.c
@@ -1,5 +1,5 @@
 /*
-Copyright 2010,2011 Jun WAKO <wakojun@gmail.com>
+Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
 
 This software is licensed with a Modified BSD License.
 All of this is supposed to be Free Software, Open Source, DFSG-free,
@@ -43,7 +43,9 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "debug.h"
 
 
+#ifndef PS2_USE_INT
 static uint8_t recv_data(void);
+#endif
 static inline void clock_lo(void);
 static inline void clock_hi(void);
 static inline bool clock_in(void);
@@ -109,12 +111,12 @@ uint8_t ps2_host_send(uint8_t data)
 #endif
     /* terminate a transmission if we have */
     inhibit();
-    _delay_us(100);
+    _delay_us(200); // at least 100us
 
     /* start bit [1] */
     data_lo();
     clock_hi();
-    WAIT(clock_lo, 15000, 1);
+    WAIT(clock_lo, 20000, 10);   // may take 15ms at most until device starts clocking
     /* data [2-9] */
     for (uint8_t i = 0; i < 8; i++) {
         _delay_us(15);
@@ -143,6 +145,9 @@ uint8_t ps2_host_send(uint8_t data)
     WAIT(clock_hi, 50, 8);
     WAIT(data_hi, 50, 9);
 
+#ifdef PS2_USE_INT
+    PS2_INT_ON();
+#endif
     res = ps2_host_recv_response();
 ERROR:
 #ifdef PS2_USE_INT
@@ -154,11 +159,15 @@ ERROR:
     return res;
 }
 
+#ifndef PS2_USE_INT
 /* receive data when host want else inhibit communication */
 uint8_t ps2_host_recv_response(void)
 {
     uint8_t data = 0;
 
+#ifdef PS2_USE_INT
+    PS2_INT_OFF();
+#endif
     /* terminate a transmission if we have */
     inhibit();
     _delay_us(100);
@@ -167,12 +176,13 @@ uint8_t ps2_host_recv_response(void)
     idle();
 
     /* wait start bit */
-    wait_clock_lo(2000);
+    wait_clock_lo(25000);    // command response may take 20 ms at most
     data = recv_data();
 
     inhibit();
     return data;
 }
+#endif
 
 #ifndef PS2_USE_INT
 uint8_t ps2_host_recv(void)
@@ -187,9 +197,6 @@ static uint8_t pbuf_head = 0;
 static uint8_t pbuf_tail = 0;
 static inline void pbuf_enqueue(uint8_t data)
 {
-    if (!data)
-        return;
-
     uint8_t sreg = SREG;
     cli();
     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
@@ -215,6 +222,21 @@ static inline uint8_t pbuf_dequeue(void)
 
     return val;
 }
+static inline bool pbuf_has_data(void)
+{
+    uint8_t sreg = SREG;
+    cli();
+    bool has_data = (pbuf_head != pbuf_tail);
+    SREG = sreg;
+    return has_data;
+}
+static inline void pbuf_clear(void)
+{
+    uint8_t sreg = SREG;
+    cli();
+    pbuf_head = pbuf_tail = 0;
+    SREG = sreg;
+}
 
 /* get data received by interrupt */
 uint8_t ps2_host_recv(void)
@@ -229,13 +251,12 @@ uint8_t ps2_host_recv(void)
     return pbuf_dequeue();
 }
 
-#if 0
-#define DEBUGP_INIT() do { DDRC = 0xFF; } while (0)
-#define DEBUGP(x) do { PORTC = x; } while (0)
-#else
-#define DEBUGP_INIT()
-#define DEBUGP(x)
-#endif
+uint8_t ps2_host_recv_response(void)
+{
+    while (!pbuf_has_data()) ;
+    return pbuf_dequeue();
+}
+
 ISR(PS2_INT_VECT)
 {
     static enum {
@@ -256,7 +277,6 @@ ISR(PS2_INT_VECT)
     }
 
     state++;
-    DEBUGP(state);
     switch (state) {
         case START:
             if (data_in())
@@ -289,6 +309,7 @@ ISR(PS2_INT_VECT)
             if (!data_in())
                 goto ERROR;
             pbuf_enqueue(data);
+//phex(data);
             goto DONE;
             break;
         default:
@@ -296,7 +317,6 @@ ISR(PS2_INT_VECT)
     }
     goto RETURN;
 ERROR:
-    DEBUGP(0x0F);
     inhibit();
     ps2_error = state;
 DONE:
@@ -309,11 +329,6 @@ RETURN:
 #endif
 
 
-static void ps2_reset(void)
-{
-    ps2_host_send(0xFF);
-}
-
 /* send LED state to keyboard */
 void ps2_host_set_led(uint8_t led)
 {
@@ -322,6 +337,7 @@ void ps2_host_set_led(uint8_t led)
 }
 
 
+#ifndef PS2_USE_INT
 /* called after start bit comes */
 static uint8_t recv_data(void)
 {
@@ -361,6 +377,7 @@ static uint8_t recv_data(void)
 ERROR:
     return 0;
 }
+#endif
 
 static inline void clock_lo()
 {
diff --git a/protocol/ps2_mouse.c b/protocol/ps2_mouse.c
index f796b2b4d..4702f12c4 100644
--- a/protocol/ps2_mouse.c
+++ b/protocol/ps2_mouse.c
@@ -1,5 +1,5 @@
 /*
-Copyright 2011 Jun Wako <wakojun@gmail.com>
+Copyright 2011,2013 Jun Wako <wakojun@gmail.com>
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -20,199 +20,196 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include<util/delay.h>
 #include "ps2.h"
 #include "ps2_mouse.h"
-#include "usb_mouse.h"
+#include "report.h"
+#include "host.h"
+#include "timer.h"
+#include "print.h"
+#include "debug.h"
 
-#define PS2_MOUSE_DEBUG
-#ifdef PS2_MOUSE_DEBUG
-#   include "print.h"
-#   include "debug.h"
-#else
-#   define print(s)
-#   define phex(h)
-#   define phex16(h)
-#endif
 
-// disable when errors occur 255 times.
-#define ERROR_RETURN() do { \
-    if (ps2_error) { \
-        if (ps2_mouse_error_count < 255) { \
-            ps2_mouse_error_count++; \
-        } else { \
-            ps2_mouse_error_count = 0; \
-            ps2_mouse_enable = false; \
-        } \
-        return ps2_error; \
-    } \
-} while (0)
+static report_mouse_t mouse_report = {};
 
 
-/*
-TODO
-----
-- Stream mode
-- Tracpoint command support: needed
-- Middle button + move = Wheel traslation
-*/
-bool ps2_mouse_enable = true;
-uint8_t ps2_mouse_x = 0;
-uint8_t ps2_mouse_y = 0;
-uint8_t ps2_mouse_btn = 0;
-uint8_t ps2_mouse_error_count = 0;
-
-static uint8_t ps2_mouse_btn_prev = 0;
+static void print_usb_data(void);
 
 
+/* supports only 3 button mouse at this time */
 uint8_t ps2_mouse_init(void) {
     uint8_t rcv;
 
-    if (!ps2_mouse_enable) return 1;
-
     ps2_host_init();
 
-    // Reset
-    rcv = ps2_host_send(0xFF);
-    print("ps2_mouse_init: send 0xFF: ");
-    phex(ps2_error); print("\n");
-    ERROR_RETURN();
+    _delay_ms(1000);    // wait for powering up
 
-    // ACK
-    rcv = ps2_host_recv();
-    print("ps2_mouse_init: read ACK: ");
+    // send Reset
+    rcv = ps2_host_send(0xFF);
+    print("ps2_mouse_init: send Reset: ");
     phex(rcv); phex(ps2_error); print("\n");
-    ERROR_RETURN();
 
-    // BAT takes some time
-    _delay_ms(100);
-    rcv = ps2_host_recv();
+    // read completion code of BAT
+    rcv = ps2_host_recv_response();
     print("ps2_mouse_init: read BAT: ");
     phex(rcv); phex(ps2_error); print("\n");
-    ERROR_RETURN();
 
-    // Device ID
-    rcv = ps2_host_recv();
+    // read Device ID
+    rcv = ps2_host_recv_response();
     print("ps2_mouse_init: read DevID: ");
     phex(rcv); phex(ps2_error); print("\n");
-    ERROR_RETURN();
 
-    // Enable data reporting
-    ps2_host_send(0xF4);
-    print("ps2_mouse_init: send 0xF4: ");
-    phex(ps2_error); print("\n");
-    ERROR_RETURN();
-
-    // ACK
-    rcv = ps2_host_recv();
-    print("ps2_mouse_init: read ACK: ");
-    phex(rcv); phex(ps2_error); print("\n");
-    ERROR_RETURN();
-
-    // Set Remote mode
-    ps2_host_send(0xF0);
+    // send Set Remote mode
+    rcv = ps2_host_send(0xF0);
     print("ps2_mouse_init: send 0xF0: ");
-    phex(ps2_error); print("\n");
-    ERROR_RETURN();
-
-    // ACK
-    rcv = ps2_host_recv();
-    print("ps2_mouse_init: read ACK: ");
     phex(rcv); phex(ps2_error); print("\n");
-    ERROR_RETURN();
 
     return 0;
 }
 
-/*
-Data format:
-    bit: 7       6       5       4       3       2       1       0
------------------------------------------------------------------------
-0   btn: Yovflw  Xovflw  Ysign   Xsign   1       Middle  Right   Left
-1   x:   X movement(0-255)
-2   y:   Y movement(0-255)
-*/
-uint8_t ps2_mouse_read(void)
+#define X_IS_NEG  (mouse_report.buttons & (1<<PS2_MOUSE_X_SIGN))
+#define Y_IS_NEG  (mouse_report.buttons & (1<<PS2_MOUSE_Y_SIGN))
+#define X_IS_OVF  (mouse_report.buttons & (1<<PS2_MOUSE_X_OVFLW))
+#define Y_IS_OVF  (mouse_report.buttons & (1<<PS2_MOUSE_Y_OVFLW))
+void ps2_mouse_task(void)
 {
+    enum { SCROLL_NONE, SCROLL_BTN, SCROLL_SENT };
+    static uint8_t scroll_state = SCROLL_NONE;
+    static uint8_t buttons_prev = 0;
+
+    /* receives packet from mouse */
     uint8_t rcv;
+    rcv = ps2_host_send(PS2_MOUSE_READ_DATA);
+    if (rcv == PS2_ACK) {
+        mouse_report.buttons = ps2_host_recv_response();
+        mouse_report.x = ps2_host_recv_response();
+        mouse_report.y = ps2_host_recv_response();
+    } else {
+        if (!debug_mouse) print("ps2_mouse: fail to get mouse packet\n");
+        return;
+    }
 
-    if (!ps2_mouse_enable) return 1;
+    /* if mouse moves or buttons state changes */
+    if (mouse_report.x || mouse_report.y ||
+            ((mouse_report.buttons ^ buttons_prev) & PS2_MOUSE_BTN_MASK)) {
 
-    ps2_host_send(0xEB);
-    ERROR_RETURN();
+#ifdef PS2_MOUSE_DEBUG
+        print("ps2_mouse raw: [");
+        phex(mouse_report.buttons); print("|");
+        print_hex8((uint8_t)mouse_report.x); print(" ");
+        print_hex8((uint8_t)mouse_report.y); print("]\n");
+#endif
 
-    rcv=ps2_host_recv();
-    ERROR_RETURN();
+        buttons_prev = mouse_report.buttons;
+
+        // PS/2 mouse data is '9-bit integer'(-256 to 255) which is comprised of sign-bit and 8-bit value.
+        // bit: 8    7 ... 0
+        //      sign \8-bit/
+        //
+        // Meanwhile USB HID mouse indicates 8bit data(-127 to 127), note that -128 is not used.
+        //
+        // This converts PS/2 data into HID value. Use only -127-127 out of PS/2 9-bit.
+        mouse_report.x = X_IS_NEG ?
+                          ((!X_IS_OVF && -127 <= mouse_report.x && mouse_report.x <= -1) ?  mouse_report.x : -127) :
+                          ((!X_IS_OVF && 0 <= mouse_report.x && mouse_report.x <= 127) ? mouse_report.x : 127);
+        mouse_report.y = Y_IS_NEG ?
+                          ((!Y_IS_OVF && -127 <= mouse_report.y && mouse_report.y <= -1) ?  mouse_report.y : -127) :
+                          ((!Y_IS_OVF && 0 <= mouse_report.y && mouse_report.y <= 127) ? mouse_report.y : 127);
+
+        // remove sign and overflow flags
+        mouse_report.buttons &= PS2_MOUSE_BTN_MASK;
+
+        // invert coordinate of y to conform to USB HID mouse
+        mouse_report.y = -mouse_report.y;
+
+
+#if PS2_MOUSE_SCROLL_BTN_MASK
+        static uint16_t scroll_button_time = 0;
+        if ((mouse_report.buttons & (PS2_MOUSE_SCROLL_BTN_MASK)) == (PS2_MOUSE_SCROLL_BTN_MASK)) {
+            if (scroll_state == SCROLL_NONE) {
+                scroll_button_time = timer_read();
+                scroll_state = SCROLL_BTN;
+            }
 
-    if(rcv==0xFA) {
-        ps2_mouse_btn = ps2_host_recv();
-        ERROR_RETURN();
-        ps2_mouse_x = ps2_host_recv();
-        ERROR_RETURN();
-        ps2_mouse_y = ps2_host_recv();
-        ERROR_RETURN();
-    }
-    return 0;
-}
+            // doesn't send Scroll Button
+            //mouse_report.buttons &= ~(PS2_MOUSE_SCROLL_BTN_MASK);
 
-bool ps2_mouse_changed(void)
-{
-    return (ps2_mouse_x || ps2_mouse_y || (ps2_mouse_btn & PS2_MOUSE_BTN_MASK) != ps2_mouse_btn_prev);
-}
+            if (mouse_report.x || mouse_report.y) {
+                scroll_state = SCROLL_SENT;
 
-#define PS2_MOUSE_SCROLL_BUTTON 0x04
-void ps2_mouse_usb_send(void)
-{
-    static bool scrolled = false;
-
-    if (!ps2_mouse_enable) return;
-
-    if (ps2_mouse_changed()) {
-        int8_t x, y, v, h;
-        x = y = v = h = 0;
-
-        // convert scale of X, Y: PS/2(-256/255) -> USB(-127/127)
-        if (ps2_mouse_btn & (1<<PS2_MOUSE_X_SIGN))
-            x = ps2_mouse_x > 128 ? (int8_t)ps2_mouse_x : -127;
-        else
-            x = ps2_mouse_x < 128 ? (int8_t)ps2_mouse_x : 127;
-
-        if (ps2_mouse_btn & (1<<PS2_MOUSE_Y_SIGN))
-            y = ps2_mouse_y > 128 ? (int8_t)ps2_mouse_y : -127;
-        else
-            y = ps2_mouse_y < 128 ? (int8_t)ps2_mouse_y : 127;
-
-        // Y is needed to reverse
-        y = -y;
-
-        if (ps2_mouse_btn & PS2_MOUSE_SCROLL_BUTTON) {
-            // scroll
-            if (x > 0 || x < 0) h = (x > 64 ? 64 : (x < -64 ? -64 :x));
-            if (y > 0 || y < 0) v = (y > 64 ? 64 : (y < -64 ? -64 :y));
-            if (h || v) {
-                scrolled = true;
-                usb_mouse_send(0,0, -v/16, h/16, 0);
+                mouse_report.v = -mouse_report.y/(PS2_MOUSE_SCROLL_DIVISOR_V);
+                mouse_report.h =  mouse_report.x/(PS2_MOUSE_SCROLL_DIVISOR_H);
+                mouse_report.x = 0;
+                mouse_report.y = 0;
+                //host_mouse_send(&mouse_report);
+            }
+        }
+        else if ((mouse_report.buttons & (PS2_MOUSE_SCROLL_BTN_MASK)) == 0) {
+#if PS2_MOUSE_SCROLL_BTN_SEND
+            if (scroll_state == SCROLL_BTN &&
+                    TIMER_DIFF_16(timer_read(), scroll_button_time) < PS2_MOUSE_SCROLL_BTN_SEND) {
+                // send Scroll Button(down and up at once) when not scrolled
+                mouse_report.buttons |= (PS2_MOUSE_SCROLL_BTN_MASK);
+                host_mouse_send(&mouse_report);
                 _delay_ms(100);
+                mouse_report.buttons &= ~(PS2_MOUSE_SCROLL_BTN_MASK);
             }
-        } else if (!scrolled && (ps2_mouse_btn_prev & PS2_MOUSE_SCROLL_BUTTON)) {
-            usb_mouse_send(0,0,0,0, PS2_MOUSE_SCROLL_BUTTON);
-            _delay_ms(100);
-            usb_mouse_send(0,0,0,0, 0);
-        } else { 
-            scrolled = false;
-            usb_mouse_send(x, y, 0, 0, ps2_mouse_btn & PS2_MOUSE_BTN_MASK);
+#endif
+            scroll_state = SCROLL_NONE;
         }
+        // doesn't send Scroll Button
+        mouse_report.buttons &= ~(PS2_MOUSE_SCROLL_BTN_MASK);
+#endif
+
 
-        ps2_mouse_btn_prev = (ps2_mouse_btn & PS2_MOUSE_BTN_MASK);
-        ps2_mouse_print();
+        host_mouse_send(&mouse_report);
+        print_usb_data();
     }
-    ps2_mouse_x = 0;
-    ps2_mouse_y = 0;
-    ps2_mouse_btn = 0;
+    // clear report
+    mouse_report.x = 0;
+    mouse_report.y = 0;
+    mouse_report.v = 0;
+    mouse_report.h = 0;
+    mouse_report.buttons = 0;
 }
 
-void ps2_mouse_print(void)
+static void print_usb_data(void)
 {
     if (!debug_mouse) return;
-    print("ps2_mouse[btn|x y]: ");
-    phex(ps2_mouse_btn); print("|");
-    phex(ps2_mouse_x); print(" ");
-    phex(ps2_mouse_y); print("\n");
+    print("ps2_mouse usb: [");
+    phex(mouse_report.buttons); print("|");
+    print_hex8((uint8_t)mouse_report.x); print(" ");
+    print_hex8((uint8_t)mouse_report.y); print(" ");
+    print_hex8((uint8_t)mouse_report.v); print(" ");
+    print_hex8((uint8_t)mouse_report.h); print("]\n");
 }
+
+
+/* PS/2 Mouse Synopsis
+ * http://www.computer-engineering.org/ps2mouse/
+ *
+ * Command:
+ * 0xFF: Reset
+ * 0xF6: Set Defaults Sampling; rate=100, resolution=4cnt/mm, scaling=1:1, reporting=disabled
+ * 0xF5: Disable Data Reporting
+ * 0xF4: Enable Data Reporting
+ * 0xF3: Set Sample Rate
+ * 0xF2: Get Device ID
+ * 0xF0: Set Remote Mode
+ * 0xEB: Read Data
+ * 0xEA: Set Stream Mode
+ * 0xE9: Status Request
+ * 0xE8: Set Resolution
+ * 0xE7: Set Scaling 2:1
+ * 0xE6: Set Scaling 1:1
+ *
+ * Mode:
+ * Stream Mode: devices sends the data when it changs its state
+ * Remote Mode: host polls the data periodically
+ *
+ * This code uses Remote Mode and polls the data with Read Data(0xEB).
+ *
+ * Data format:
+ * byte|7       6       5       4       3       2       1       0
+ * ----+--------------------------------------------------------------
+ *    0|Yovflw  Xovflw  Ysign   Xsign   1       Middle  Right   Left
+ *    1|                    X movement
+ *    2|                    Y movement
+ */
diff --git a/protocol/ps2_mouse.h b/protocol/ps2_mouse.h
index 4529ce113..27d9790d4 100644
--- a/protocol/ps2_mouse.h
+++ b/protocol/ps2_mouse.h
@@ -20,6 +20,16 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <stdbool.h>
 
+#define PS2_MOUSE_READ_DATA     0xEB
+
+/*
+ * Data format:
+ * byte|7       6       5       4       3       2       1       0
+ * ----+--------------------------------------------------------------
+ *    0|Yovflw  Xovflw  Ysign   Xsign   1       Middle  Right   Left
+ *    1|                    X movement(0-255)
+ *    2|                    Y movement(0-255)
+ */
 #define PS2_MOUSE_BTN_MASK      0x07
 #define PS2_MOUSE_BTN_LEFT      0
 #define PS2_MOUSE_BTN_RIGHT     1
@@ -29,16 +39,28 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define PS2_MOUSE_X_OVFLW       6
 #define PS2_MOUSE_Y_OVFLW       7
 
-bool ps2_mouse_enable;
-extern uint8_t ps2_mouse_x;
-extern uint8_t ps2_mouse_y;
-extern uint8_t ps2_mouse_btn;
-extern uint8_t ps2_mouse_error_count;
+
+/*
+ * Scroll by mouse move with pressing button
+ */
+/* mouse button to start scrolling; set 0 to disable scroll */
+#ifndef PS2_MOUSE_SCROLL_BTN_MASK
+#define PS2_MOUSE_SCROLL_BTN_MASK       (1<<PS2_MOUSE_BTN_MIDDLE)
+#endif
+/* send button event when button is released within this value(ms); set 0 to disable  */
+#ifndef PS2_MOUSE_SCROLL_BTN_SEND
+#define PS2_MOUSE_SCROLL_BTN_SEND       300
+#endif
+/* divide virtical and horizontal mouse move by this to convert to scroll move */
+#ifndef PS2_MOUSE_SCROLL_DIVISOR_V
+#define PS2_MOUSE_SCROLL_DIVISOR_V      2
+#endif
+#ifndef PS2_MOUSE_SCROLL_DIVISOR_H
+#define PS2_MOUSE_SCROLL_DIVISOR_H      2
+#endif
+
 
 uint8_t ps2_mouse_init(void);
-uint8_t ps2_mouse_read(void);
-bool ps2_mouse_changed(void);
-void ps2_mouse_usb_send(void);
-void ps2_mouse_print(void);
+void ps2_mouse_task(void);
 
 #endif
diff --git a/protocol/ps2_usart.c b/protocol/ps2_usart.c
index 9ea6b7786..40c46c497 100644
--- a/protocol/ps2_usart.c
+++ b/protocol/ps2_usart.c
@@ -1,5 +1,5 @@
 /*
-Copyright 2010,2011 Jun WAKO <wakojun@gmail.com>
+Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
 
 This software is licensed with a Modified BSD License.
 All of this is supposed to be Free Software, Open Source, DFSG-free,
@@ -64,14 +64,6 @@ http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
 #include "debug.h"
 
 
-#if 0
-#define DEBUGP_INIT() do { DDRC = 0xFF; } while (0)
-#define DEBUGP(x) do { PORTC = x; } while (0)
-#else
-#define DEBUGP_INIT()
-#define DEBUGP(x)
-#endif
-
 #define WAIT(stat, us, err) do { \
     if (!wait_##stat(us)) { \
         ps2_error = err; \
@@ -97,12 +89,12 @@ static inline void idle(void);
 static inline void inhibit(void);
 static inline uint8_t pbuf_dequeue(void);
 static inline void pbuf_enqueue(uint8_t data);
+static inline bool pbuf_has_data(void);
+static inline void pbuf_clear(void);
 
 
 void ps2_host_init(void)
 {
-    DEBUGP_INIT();
-    DEBUGP(0x1);
     idle();
     PS2_USART_INIT();
     PS2_USART_RX_INT_ON();
@@ -114,7 +106,6 @@ uint8_t ps2_host_send(uint8_t data)
     bool parity = true;
     ps2_error = PS2_ERR_NONE;
 
-    DEBUGP(0x6);
     PS2_USART_OFF();
 
     /* terminate a transmission if we have */
@@ -153,6 +144,8 @@ uint8_t ps2_host_send(uint8_t data)
     WAIT(clock_hi, 50, 8);
     WAIT(data_hi, 50, 9);
 
+    PS2_USART_INIT();
+    PS2_USART_RX_INT_ON();
     res = ps2_host_recv_response();
 ERROR:
     idle();
@@ -164,15 +157,10 @@ ERROR:
 // Do polling data from keyboard to get response to last command.
 uint8_t ps2_host_recv_response(void)
 {
-    uint8_t data = 0;
-    PS2_USART_INIT();
-    PS2_USART_RX_POLL_ON();
-    while (!PS2_USART_RX_READY)
-        ;
-    data = PS2_USART_RX_DATA;
-    PS2_USART_OFF();
-    DEBUGP(0x9);
-    return data;
+    while (!pbuf_has_data()) {
+        _delay_ms(1);   // without this delay it seems to fall into deadlock
+    }
+    return pbuf_dequeue();
 }
 
 uint8_t ps2_host_recv(void)
@@ -182,15 +170,11 @@ uint8_t ps2_host_recv(void)
 
 ISR(PS2_USART_RX_VECT)
 {
-    DEBUGP(0x7);
     uint8_t error = PS2_USART_ERROR;
     uint8_t data = PS2_USART_RX_DATA;
-    if (error) {
-        DEBUGP(error>>2);
-    } else {
+    if (!error) {
         pbuf_enqueue(data);
     }
-    DEBUGP(0x8);
 }
 
 /* send LED state to keyboard */
@@ -293,9 +277,6 @@ static uint8_t pbuf_head = 0;
 static uint8_t pbuf_tail = 0;
 static inline void pbuf_enqueue(uint8_t data)
 {
-    if (!data)
-        return;
-
     uint8_t sreg = SREG;
     cli();
     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
@@ -322,3 +303,18 @@ static inline uint8_t pbuf_dequeue(void)
 
     return val;
 }
+static inline bool pbuf_has_data(void)
+{
+    uint8_t sreg = SREG;
+    cli();
+    bool has_data = (pbuf_head != pbuf_tail);
+    SREG = sreg;
+    return has_data;
+}
+static inline void pbuf_clear(void)
+{
+    uint8_t sreg = SREG;
+    cli();
+    pbuf_head = pbuf_tail = 0;
+    SREG = sreg;
+}