1 files changed, 248 insertions, 0 deletions

diff --git a/ps2.c b/ps2.c
new file mode 100644
index 000000000..adb425ae3
--- /dev/null
+++ b/ps2.c
@@ -0,0 +1,248 @@
+/*
+Copyright (c) 2010 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,
+GPL-compatible, and OK to use in both free and proprietary applications.
+Additions and corrections to this file are welcome.
+
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+
+* 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.
+
+* Neither the name of the copyright holders nor the names of
+  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.
+*/
+#include <stdbool.h>
+#include <avr/io.h>
+#include <util/delay.h>
+#include "ps2.h"
+#include "print.h"
+#include "debug.h"
+
+
+static inline void clock_lo(void);
+static inline void clock_hi(void);
+static inline bool clock_in(void);
+static inline void data_lo(void);
+static inline void data_hi(void);
+static inline bool data_in(void);
+static inline uint16_t wait_clock_lo(uint16_t us);
+static inline uint16_t wait_clock_hi(uint16_t us);
+static inline uint16_t wait_data_lo(uint16_t us);
+static inline uint16_t wait_data_hi(uint16_t us);
+
+
+/*
+Primitive PS/2 Library for AVR
+==============================
+Host side is only supported now.
+
+
+I/O control
+-----------
+High state is asserted by input with pull up.
+
+
+PS/2 References
+---------------
+http://www.computer-engineering.org/ps2protocol/
+http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
+*/
+
+
+#define WAIT(stat, us, err) do { \
+    if (!wait_##stat(us)) { \
+        ps2_error = err; \
+        goto ERROR; \
+    } \
+} while (0)
+
+#define WAIT_NORETRY(stat, us, err) do { \
+    if (!wait_##stat(us)) { \
+        ps2_error = err; \
+        return 0; \
+    } \
+} while (0)
+
+
+uint8_t ps2_error = PS2_ERR_NONE;
+
+
+void ps2_host_init(void)
+{
+    /* inhibit */
+    clock_lo();
+    data_hi();
+}
+
+uint8_t ps2_host_send(uint8_t data)
+{
+    bool parity = true;
+    ps2_error = 0;
+
+    /* request to send */
+    clock_lo();
+    data_lo();
+    _delay_us(100);
+    /* start bit [1] */
+    clock_hi();
+    WAIT(clock_lo, 15000, 1);
+    /* data [2-9] */
+    for (uint8_t i = 0; i < 8; i++) {
+        if (data&(1<<i)) {
+            parity = !parity;
+            data_hi();
+        } else {
+            data_lo();
+        }
+        WAIT(clock_hi, 50, 2);
+        WAIT(clock_lo, 50, 3);
+    }
+    /* parity [10] */
+    if (parity) { data_hi(); } else { data_lo(); }
+    WAIT(clock_hi, 50, 4);
+    WAIT(clock_lo, 50, 5);
+    /* stop bit [11] */
+    data_hi();
+    /* ack [12] */
+    WAIT(data_lo, 50, 6);
+    WAIT(clock_lo, 50, 7);
+    WAIT(clock_hi, 50, 8);
+    WAIT(data_hi, 50, 9);
+
+    /* inhibit device to send */
+    clock_lo();
+
+    return 1;
+ERROR:
+    return 0;
+}
+
+uint8_t ps2_host_recv(void)
+{
+    uint8_t data = 0;
+    bool parity = true;
+    ps2_error = 0;
+
+    /* cancel to sync */
+    clock_lo();
+    _delay_us(100);
+
+    /* release lines(idle state) */
+    clock_hi();
+    data_hi();
+
+    /* start bit [1] */
+    WAIT(clock_lo, 20000, 1);
+    WAIT(data_lo, 1, 2);
+    WAIT(clock_hi, 50, 3);
+
+    /* data [2-9] */
+    for (uint8_t i = 0; i < 8; i++) {
+        WAIT(clock_lo, 50, 4);
+        if (data_in()) {
+            parity = !parity;
+            data |= (1<<i);
+        }
+        WAIT(clock_hi, 50, 5);
+    }
+
+    /* parity [10] */
+    WAIT(clock_lo, 50, 6);
+    if (data_in() != parity) {
+        ps2_error = PS2_ERR_PARITY;
+        goto ERROR;
+    }
+    WAIT(clock_hi, 50, 7);
+
+    /* stop bit [11] */
+    WAIT(clock_lo, 50, 8);
+    WAIT(data_hi, 1, 9);
+    WAIT(clock_hi, 50, 10);
+
+    /* inhibit device to send */
+    clock_lo();
+
+    return data;
+ERROR:
+    return 0;
+}
+
+
+static inline void clock_lo()
+{
+    PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
+    PS2_CLOCK_DDR  |=  (1<<PS2_CLOCK_BIT);
+}
+static inline void clock_hi()
+{
+    /* input with pull up */
+    PS2_CLOCK_DDR  &= ~(1<<PS2_CLOCK_BIT);
+    PS2_CLOCK_PORT |=  (1<<PS2_CLOCK_BIT);
+}
+static inline bool clock_in()
+{
+    PS2_CLOCK_DDR  &= ~(1<<PS2_CLOCK_BIT);
+    PS2_CLOCK_PORT |=  (1<<PS2_CLOCK_BIT);
+    return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT);
+}
+static inline void data_lo()
+{
+    PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
+    PS2_DATA_DDR  |=  (1<<PS2_DATA_BIT);
+}
+static inline void data_hi()
+{
+    /* input with pull up */
+    PS2_DATA_DDR  &= ~(1<<PS2_DATA_BIT);
+    PS2_DATA_PORT |=  (1<<PS2_DATA_BIT);
+}
+static inline bool data_in()
+{
+    PS2_DATA_DDR  &= ~(1<<PS2_DATA_BIT);
+    PS2_DATA_PORT |=  (1<<PS2_DATA_BIT);
+    return PS2_DATA_PIN&(1<<PS2_DATA_BIT);
+}
+
+static inline uint16_t wait_clock_lo(uint16_t us)
+{
+    while (clock_in()  && us) { asm(""); _delay_us(1); us--; }
+    return us;
+}
+static inline uint16_t wait_clock_hi(uint16_t us)
+{
+    while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
+    return us;
+}
+static inline uint16_t wait_data_lo(uint16_t us)
+{
+    while (data_in() && us)  { asm(""); _delay_us(1); us--; }
+    return us;
+}
+static inline uint16_t wait_data_hi(uint16_t us)
+{
+    while (!data_in() && us)  { asm(""); _delay_us(1); us--; }
+    return us;
+}