tmk
11 years ago
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/*
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Copyright 2010,2011,2012,2013 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 <util/delay.h>
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#include "ps2.h"
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#include "debug.h"
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/*
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* PS/2 protocol busywait version
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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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// POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
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_delay_ms(2500);
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inhibit();
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}
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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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/* terminate a transmission if we have */
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inhibit();
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_delay_us(200); // at least 100us
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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, 20000, 10); // may take 15ms at most until device starts clocking
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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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inhibit();
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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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// TODO:
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// Command might take 20ms to response([3]p.21)
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// TrackPoint might take 25ms ([5]2.7)
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uint8_t data = 0;
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uint8_t try = 200;
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while (try-- && (data = ps2_host_recv())) ;
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return data;
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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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uint8_t ps2_host_recv(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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/* release lines(idle state) */
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idle();
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/* start bit [1] */
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WAIT(clock_lo, 100, 1); // TODO: this is enough?
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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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inhibit();
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return data;
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ERROR:
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if (ps2_error > PS2_ERR_STARTBIT3) {
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printf("x%02X\n", ps2_error);
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}
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inhibit();
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return 0;
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}
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