421 lines
9.4 KiB
C
421 lines
9.4 KiB
C
/*
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Copyright (c) 2010,2011 Jun WAKO <wakojun@gmail.com>
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This software is licensed with a Modified BSD License.
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All of this is supposed to be Free Software, Open Source, DFSG-free,
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GPL-compatible, and OK to use in both free and proprietary applications.
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Additions and corrections to this file are welcome.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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distribution.
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* Neither the name of the copyright holders nor the names of
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdbool.h>
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/delay.h>
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#include "ps2.h"
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#include "debug.h"
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static uint8_t recv_data(void);
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static inline void clock_lo(void);
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static inline void clock_hi(void);
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static inline bool clock_in(void);
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static inline void data_lo(void);
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static inline void data_hi(void);
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static inline bool data_in(void);
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static inline uint16_t wait_clock_lo(uint16_t us);
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static inline uint16_t wait_clock_hi(uint16_t us);
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static inline uint16_t wait_data_lo(uint16_t us);
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static inline uint16_t wait_data_hi(uint16_t us);
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static inline void idle(void);
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static inline void inhibit(void);
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/*
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Primitive PS/2 Library for AVR
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==============================
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Host side is only supported now.
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I/O control
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-----------
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High state is asserted by input with pull up.
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PS/2 References
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---------------
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http://www.computer-engineering.org/ps2protocol/
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http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
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*/
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#define WAIT(stat, us, err) do { \
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if (!wait_##stat(us)) { \
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ps2_error = err; \
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goto ERROR; \
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} \
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} while (0)
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uint8_t ps2_error = PS2_ERR_NONE;
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void ps2_host_init(void)
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{
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#ifdef PS2_INT_ENABLE
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PS2_INT_ENABLE();
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idle();
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#else
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inhibit();
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#endif
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}
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// TODO: send using interrupt if available
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uint8_t ps2_host_send(uint8_t data)
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{
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uint8_t res = 0;
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bool parity = true;
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ps2_error = PS2_ERR_NONE;
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#ifdef PS2_INT_DISABLE
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PS2_INT_DISABLE();
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#endif
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/* terminate a transmission if we have */
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inhibit();
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_delay_us(100);
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/* start bit [1] */
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data_lo();
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clock_hi();
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WAIT(clock_lo, 15000, 1);
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/* data [2-9] */
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for (uint8_t i = 0; i < 8; i++) {
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_delay_us(15);
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if (data&(1<<i)) {
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parity = !parity;
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data_hi();
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} else {
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data_lo();
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}
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WAIT(clock_hi, 50, 2);
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WAIT(clock_lo, 50, 3);
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}
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/* parity [10] */
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_delay_us(15);
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if (parity) { data_hi(); } else { data_lo(); }
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WAIT(clock_hi, 50, 4);
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WAIT(clock_lo, 50, 5);
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/* stop bit [11] */
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_delay_us(15);
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data_hi();
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/* ack [12] */
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WAIT(data_lo, 50, 6);
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WAIT(clock_lo, 50, 7);
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/* wait for idle state */
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WAIT(clock_hi, 50, 8);
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WAIT(data_hi, 50, 9);
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res = ps2_host_recv_response();
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ERROR:
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#ifdef PS2_INT_ENABLE
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PS2_INT_ENABLE();
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idle();
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#else
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inhibit();
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#endif
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return res;
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}
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/* receive data when host want else inhibit communication */
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uint8_t ps2_host_recv_response(void)
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{
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uint8_t data = 0;
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/* terminate a transmission if we have */
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inhibit();
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_delay_us(100);
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/* release lines(idle state) */
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idle();
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/* wait start bit */
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wait_clock_lo(2000);
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data = recv_data();
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inhibit();
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return data;
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}
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#ifndef PS2_INT_VECT
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uint8_t ps2_host_recv(void)
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{
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return ps2_host_recv_response();
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}
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#else
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/* ring buffer to store ps/2 key data */
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#define PBUF_SIZE 8
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static uint8_t pbuf[PBUF_SIZE];
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static uint8_t pbuf_head = 0;
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static uint8_t pbuf_tail = 0;
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static inline void pbuf_enqueue(uint8_t data)
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{
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if (!data)
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return;
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uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
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if (next != pbuf_tail) {
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pbuf[pbuf_head] = data;
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pbuf_head = next;
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} else {
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debug("pbuf: full\n");
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}
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}
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static inline uint8_t pbuf_dequeue(void)
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{
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uint8_t val = 0;
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uint8_t sreg = SREG;
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cli();
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if (pbuf_head != pbuf_tail) {
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val = pbuf[pbuf_tail];
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pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
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}
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SREG = sreg;
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return val;
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}
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/* get data received by interrupt */
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uint8_t ps2_host_recv(void)
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{
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// TODO: release clock line after 100us when inhibited by error
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if (ps2_error) {
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ps2_host_send(0xFE); // request to resend
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ps2_error = PS2_ERR_NONE;
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}
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return pbuf_dequeue();
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}
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#define DEBUGP_INIT() do { DDRC = 0xFF; } while (0)
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#define DEBUGP(x) do { PORTC = x; } while (0)
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ISR(PS2_INT_VECT)
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{
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static enum {
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INIT,
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START,
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BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
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PARITY,
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STOP,
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} state = INIT;
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static uint8_t data = 0;
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static uint8_t parity = 1;
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// TODO: abort if elapse 100us from previous interrupt
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// return unless falling edge
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if (clock_in()) {
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goto RETURN;
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}
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state++;
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DEBUGP(state);
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switch (state) {
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case START:
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if (data_in())
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goto ERROR;
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break;
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case BIT0:
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case BIT1:
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case BIT2:
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case BIT3:
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case BIT4:
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case BIT5:
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case BIT6:
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case BIT7:
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data >>= 1;
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if (data_in()) {
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data |= 0x80;
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parity++;
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}
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break;
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case PARITY:
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if (data_in()) {
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if (!(parity & 0x01))
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goto ERROR;
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} else {
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if (parity & 0x01)
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goto ERROR;
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}
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break;
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case STOP:
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if (!data_in())
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goto ERROR;
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pbuf_enqueue(data);
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goto DONE;
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break;
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default:
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goto ERROR;
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}
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goto RETURN;
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ERROR:
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DEBUGP(0xFF);
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inhibit();
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ps2_error = state;
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DONE:
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state = INIT;
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data = 0;
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parity = 1;
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RETURN:
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return;
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}
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#endif
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static void ps2_reset(void)
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{
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ps2_host_send(0xFF);
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}
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/* send LED state to keyboard */
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void ps2_host_set_led(uint8_t led)
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{
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ps2_host_send(0xED);
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ps2_host_send(led);
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}
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/* called after start bit comes */
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static uint8_t recv_data(void)
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{
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uint8_t data = 0;
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bool parity = true;
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ps2_error = PS2_ERR_NONE;
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/* start bit [1] */
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WAIT(clock_lo, 1, 1);
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WAIT(data_lo, 1, 2);
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WAIT(clock_hi, 50, 3);
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/* data [2-9] */
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for (uint8_t i = 0; i < 8; i++) {
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WAIT(clock_lo, 50, 4);
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if (data_in()) {
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parity = !parity;
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data |= (1<<i);
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}
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WAIT(clock_hi, 50, 5);
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}
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/* parity [10] */
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WAIT(clock_lo, 50, 6);
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if (data_in() != parity) {
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ps2_error = PS2_ERR_PARITY;
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goto ERROR;
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}
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WAIT(clock_hi, 50, 7);
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/* stop bit [11] */
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WAIT(clock_lo, 50, 8);
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WAIT(data_hi, 1, 9);
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WAIT(clock_hi, 50, 10);
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return data;
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ERROR:
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return 0;
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}
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static inline void clock_lo()
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{
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PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
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PS2_CLOCK_DDR |= (1<<PS2_CLOCK_BIT);
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}
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static inline void clock_hi()
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{
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/* input with pull up */
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PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
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PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
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}
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static inline bool clock_in()
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{
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PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
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PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
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_delay_us(1);
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return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT);
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}
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static inline void data_lo()
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{
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PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
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PS2_DATA_DDR |= (1<<PS2_DATA_BIT);
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}
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static inline void data_hi()
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{
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/* input with pull up */
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PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
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PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
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}
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static inline bool data_in()
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{
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PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
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PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
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_delay_us(1);
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return PS2_DATA_PIN&(1<<PS2_DATA_BIT);
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}
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static inline uint16_t wait_clock_lo(uint16_t us)
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{
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while (clock_in() && us) { asm(""); _delay_us(1); us--; }
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return us;
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}
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static inline uint16_t wait_clock_hi(uint16_t us)
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{
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while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
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return us;
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}
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static inline uint16_t wait_data_lo(uint16_t us)
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{
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while (data_in() && us) { asm(""); _delay_us(1); us--; }
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return us;
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}
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static inline uint16_t wait_data_hi(uint16_t us)
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{
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while (!data_in() && us) { asm(""); _delay_us(1); us--; }
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return us;
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}
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/* idle state that device can send */
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static inline void idle(void)
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{
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clock_hi();
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data_hi();
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}
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/* inhibit device to send */
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static inline void inhibit(void)
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{
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clock_lo();
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data_hi();
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}
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