392 lines
12 KiB
C
392 lines
12 KiB
C
/*
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Copyright 2010,2011,2012,2013,2019 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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/*
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* IBM PC keyboard protocol
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*/
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#include <stdbool.h>
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#include <avr/interrupt.h>
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#include <util/atomic.h>
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#include "ibmpc.h"
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#include "debug.h"
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#include "timer.h"
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#include "wait.h"
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#include "ringbuf.h"
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#define WAIT(stat, us, err) do { \
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if (!wait_##stat(us)) { \
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ibmpc_error = err; \
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goto ERROR; \
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} \
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} while (0)
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volatile uint16_t ibmpc_isr_debug = 0;
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volatile uint8_t ibmpc_protocol = IBMPC_PROTOCOL_NO;
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volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
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/* buffer for data received from device */
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#define RINGBUF_SIZE 16
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static uint8_t rbuf[RINGBUF_SIZE];
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static ringbuf_t rb = {};
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/* internal state of receiving data */
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static volatile uint16_t isr_state = 0x8000;
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static uint8_t timer_start = 0;
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void ibmpc_host_init(void)
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{
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// initialize reset pin to HiZ
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IBMPC_RST_HIZ();
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inhibit();
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IBMPC_INT_INIT();
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IBMPC_INT_OFF();
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ringbuf_init(&rb, rbuf, RINGBUF_SIZE);
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}
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void ibmpc_host_enable(void)
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{
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IBMPC_INT_ON();
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idle();
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}
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void ibmpc_host_disable(void)
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{
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IBMPC_INT_OFF();
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inhibit();
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}
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int16_t ibmpc_host_send(uint8_t data)
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{
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bool parity = true;
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ibmpc_error = IBMPC_ERR_NONE;
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uint8_t retry = 0;
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dprintf("w%02X ", data);
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// Not receiving data
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if (isr_state != 0x8000) dprintf("isr:%04X ", isr_state);
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while (isr_state != 0x8000) ;
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// Not clock Lo
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if (!clock_in()) dprintf("c:%u ", wait_clock_hi(1000));
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// Not data Lo
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if (!data_in()) dprintf("d:%u ", wait_data_hi(1000));
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IBMPC_INT_OFF();
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RETRY:
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/* terminate a transmission if we have */
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inhibit();
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wait_us(200); // [5]p.54
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/* 'Request to Send' and Start bit */
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data_lo();
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wait_us(200);
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clock_hi(); // [5]p.54 [clock low]>100us [5]p.50
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WAIT(clock_lo, 10000, 1); // [5]p.53, -10ms [5]p.50
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/* Data bit[2-9] */
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for (uint8_t i = 0; i < 8; i++) {
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wait_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 bit */
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wait_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 */
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wait_us(15);
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data_hi();
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/* Ack */
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WAIT(data_lo, 300, 6);
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WAIT(data_hi, 300, 7);
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WAIT(clock_hi, 300, 8);
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// clear buffer to get response correctly
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ibmpc_host_isr_clear();
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idle();
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IBMPC_INT_ON();
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return ibmpc_host_recv_response();
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ERROR:
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// Retry for Z-150 AT start bit error
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if (ibmpc_error == 1 && retry++ < 10) {
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ibmpc_error = IBMPC_ERR_NONE;
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dprintf("R ");
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goto RETRY;
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}
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ibmpc_error |= IBMPC_ERR_SEND;
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inhibit();
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wait_ms(2);
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idle();
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IBMPC_INT_ON();
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return -1;
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}
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/*
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* Receive data from keyboard
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*/
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int16_t ibmpc_host_recv(void)
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{
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int16_t ret = -1;
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// Enable ISR if buffer was full
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if (ringbuf_is_full(&rb)) {
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ibmpc_host_isr_clear();
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IBMPC_INT_ON();
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idle();
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}
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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ret = ringbuf_get(&rb);
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}
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if (ret != -1) dprintf("r%02X ", ret&0xFF);
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return ret;
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}
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int16_t ibmpc_host_recv_response(void)
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{
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// Command may take 25ms/20ms at most([5]p.46, [3]p.21)
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uint8_t retry = 25;
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int16_t data = -1;
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while (retry-- && (data = ibmpc_host_recv()) == -1) {
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wait_ms(1);
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}
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return data;
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}
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void ibmpc_host_isr_clear(void)
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{
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ibmpc_isr_debug = 0;
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ibmpc_protocol = 0;
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ibmpc_error = 0;
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isr_state = 0x8000;
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ringbuf_reset(&rb);
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}
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#define LO8(w) (*((uint8_t *)&(w)))
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#define HI8(w) (*(((uint8_t *)&(w))+1))
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// NOTE: With this ISR data line can be read within 2us after clock falling edge.
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// To read data line early as possible:
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// write naked ISR with asembly code to read the line and call C func to do other job?
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ISR(IBMPC_INT_VECT)
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{
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uint8_t dbit;
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dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
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// Timeout check
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uint8_t t;
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// use only the least byte of millisecond timer
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asm("lds %0, %1" : "=r" (t) : "p" (&timer_count));
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//t = (uint8_t)timer_count; // compiler uses four registers instead of one
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if (isr_state == 0x8000) {
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timer_start = t;
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} else {
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// This gives 2.0ms at least before timeout
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if ((uint8_t)(t - timer_start) >= 3) {
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ibmpc_isr_debug = isr_state;
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ibmpc_error = IBMPC_ERR_TIMEOUT;
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goto ERROR;
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// timeout error recovery - start receiving new data
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// it seems to work somehow but may not under unstable situation
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//timer_start = t;
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//isr_state = 0x8000;
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}
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}
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isr_state = isr_state>>1;
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if (dbit) isr_state |= 0x8000;
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// isr_state: state of receiving data from keyboard
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//
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// This should be initialized with 0x8000 before receiving data and
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// the MSB '*1' works as marker to discrimitate between protocols.
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// It stores sampled bit at MSB after right shift on each clock falling edge.
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//
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// XT protocol has two variants of signaling; XT_IBM and XT_Clone.
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// XT_IBM uses two start bits 0 and 1 while XT_Clone uses just start bit 1.
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// https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
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//
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// 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
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// -----------------------------------------------------
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// *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 Initial state(0x8000)
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//
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// x x x x x x x x | 0 0 0 0 0 0 0 0 midway(0-7 bits received)
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// x x x x x x x x | *1 0 0 0 0 0 0 0 midway(8 bits received)
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// b6 b5 b4 b3 b2 b1 b0 1 | 0 *1 0 0 0 0 0 0 XT_IBM-midway ^1
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// b7 b6 b5 b4 b3 b2 b1 b0 | 0 *1 0 0 0 0 0 0 AT-midway ^1
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// b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 XT_Clone-done ^3
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// b6 b5 b4 b3 b2 b1 b0 1 | 1 *1 0 0 0 0 0 0 XT_IBM-error ^3
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// pr b7 b6 b5 b4 b3 b2 b1 | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
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// b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 XT_IBM-done ^2
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// pr b7 b6 b5 b4 b3 b2 b1 | 1 0 *1 0 0 0 0 0 AT-midway[b0=1] ^2
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// b7 b6 b5 b4 b3 b2 b1 b0 | 1 1 *1 0 0 0 0 0 XT_IBM-error-done
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// x x x x x x x x | x 1 1 0 0 0 0 0 illegal
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// st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 AT-done
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// x x x x x x x x | x x 1 *1 0 0 0 0 illegal
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// all other states than above illegal
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//
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// ^1: AT and XT_IBM takes same state.
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// ^2: AT and XT_IBM takes same state in case that AT b0 is 1,
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// we have to check AT stop bit to discriminate between the two protocol.
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switch (isr_state & 0xFF) {
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case 0b00000000:
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case 0b10000000:
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case 0b01000000: // ^1
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case 0b00100000:
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// midway
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goto NEXT;
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break;
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case 0b11000000: // ^3
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{
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uint8_t us = 100;
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// wait for rising and falling edge of b7 of XT_IBM
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while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
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while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
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if (us) {
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// XT_IBM-error: read start(0) as 1
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goto NEXT;
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} else {
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// XT_Clone-done
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ibmpc_isr_debug = isr_state;
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isr_state = isr_state>>8;
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ibmpc_protocol = IBMPC_PROTOCOL_XT_CLONE;
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goto DONE;
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}
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}
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break;
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case 0b11100000:
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// XT_IBM-error-done
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ibmpc_isr_debug = isr_state;
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isr_state = isr_state>>8;
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ibmpc_protocol = IBMPC_PROTOCOL_XT_ERROR;
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goto DONE;
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break;
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case 0b10100000: // ^2
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{
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uint8_t us = 100;
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// wait for rising and falling edge of AT stop bit to discriminate between XT and AT
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while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
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while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
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if (us) {
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// found stop bit: AT-midway - process the stop bit in next ISR
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goto NEXT;
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} else {
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// no stop bit: XT_IBM-done
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ibmpc_isr_debug = isr_state;
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isr_state = isr_state>>8;
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ibmpc_protocol = IBMPC_PROTOCOL_XT_IBM;
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goto DONE;
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}
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}
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break;
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case 0b00010000:
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case 0b10010000:
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case 0b01010000:
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case 0b11010000:
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// AT-done
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// TODO: parity check?
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ibmpc_isr_debug = isr_state;
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// stop bit check
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if (isr_state & 0x8000) {
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ibmpc_protocol = IBMPC_PROTOCOL_AT;
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} else {
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// Zenith Z-150 AT(beige/white lable) asserts stop bit as low
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// https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#zenith-z-150-beige
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ibmpc_protocol = IBMPC_PROTOCOL_AT_Z150;
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}
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isr_state = isr_state>>6;
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goto DONE;
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break;
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case 0b01100000:
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case 0b00110000:
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case 0b10110000:
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case 0b01110000:
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case 0b11110000:
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default: // xxxx_oooo(any 1 in low nibble)
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// Illegal
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ibmpc_isr_debug = isr_state;
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ibmpc_error = IBMPC_ERR_ILLEGAL;
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goto ERROR;
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break;
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}
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DONE:
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// store data
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if (!ringbuf_put(&rb, isr_state & 0xFF)) {
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// buffer overflow
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ibmpc_error = IBMPC_ERR_FULL;
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// Disable ISR if buffer is full
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IBMPC_INT_OFF();
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// inhibit: clock_lo
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IBMPC_CLOCK_PORT &= ~(1<<IBMPC_CLOCK_BIT);
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IBMPC_CLOCK_DDR |= (1<<IBMPC_CLOCK_BIT);
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}
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ERROR:
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// clear for next data
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isr_state = 0x8000;
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NEXT:
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return;
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}
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/* send LED state to keyboard */
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void ibmpc_host_set_led(uint8_t led)
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{
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if (0xFA == ibmpc_host_send(0xED)) {
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ibmpc_host_send(led);
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}
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}
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