307 lines
9.4 KiB
C
307 lines
9.4 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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#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 uint8_t ibmpc_protocol = IBMPC_PROTOCOL_AT;
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volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
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/* 2-byte buffer for data received from keyhboard
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* buffer states:
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* FFFF: empty
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* FFss: one data
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* sstt: two data(full)
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* 0xFF can not be stored as data in buffer because it means empty or no data.
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*/
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static volatile uint16_t recv_data = 0xFFFF;
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/* internal state of receiving data */
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static volatile uint16_t isr_state = 0x8000;
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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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}
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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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if (ibmpc_protocol == IBMPC_PROTOCOL_XT) return -1;
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dprintf("w%02X ", data);
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IBMPC_INT_OFF();
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/* terminate a transmission if we have */
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inhibit();
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wait_us(100); // 100us [4]p.13, [5]p.50
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/* 'Request to Send' and Start bit */
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data_lo();
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clock_hi();
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WAIT(clock_lo, 10000, 1); // 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, 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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// clear buffer to get response correctly
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recv_data = 0xFFFF;
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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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ibmpc_error |= IBMPC_ERR_SEND;
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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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uint16_t data = 0;
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uint8_t ret = 0xFF;
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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data = recv_data;
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if ((data&0xFF00) != 0xFF00) { // recv_data:sstt -> recv_data:FFtt, ret:ss
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ret = (data>>8)&0x00FF;
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recv_data = data | 0xFF00;
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} else if (data != 0xFFFF) { // recv_data:FFss -> recv_data:FFFF, ret:ss
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ret = data&0x00FF;
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recv_data = data | 0x00FF;
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}
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}
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if (ret != 0xFF) dprintf("r%02X ", ret);
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if (recv_data != 0xFFFF) dprintf("b%04X ", recv_data);
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return ((ret != 0xFF) ? ret : -1);
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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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isr_state = 0x8000;
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recv_data = 0xFFFF;
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}
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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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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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// This is initialized with 0x8000 before start receiving data and MSB '1' of
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// the initial value is marker bit 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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// 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
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// -----------------------------------------------------
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// Initial: *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 with MSB marker *1
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// XT_Type-1: b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 start bit 0 and 1 **
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// XT_Type-2: b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 start bit 1
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// AT: st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 start bit 0
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// AT**: pr b7 b6 b5 b4 b3 b2 b1 | b0 0 *1 0 0 0 0 0 before stop bit **
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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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// x x x x x x x x | 0 *1 0 0 0 0 0 0 XT_Type1-midway or AT-midway
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// x x x x x x x x | 1 *1 0 0 0 0 0 0 XT_Type2-done
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// x x x x x x x x | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
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// x x x x x x x x | 1 0 *1 0 0 0 0 0 XT_Type1-done or AT-midway[b0=1]
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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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// x x x x x x x x | x x 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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// other states than above illegal
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//
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// **: AT takes same state as XT_Type1-done(1010 000) in case that AT b0 is 1,
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// to discriminate between the two protocol we will have to wait a while for AT stop bit.
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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:
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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:
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// XT_Type2-done
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recv_data = recv_data<<8;
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recv_data |= (isr_state>>8) & 0xFF;
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goto DONE;
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break;
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case 0b10100000:
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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
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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_Type1-done
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recv_data = recv_data<<8;
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recv_data |= (isr_state>>8) & 0xFF;
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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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recv_data = recv_data<<8;
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recv_data |= (isr_state>>6) & 0xFF;
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goto DONE;
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break;
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case 0b01100000:
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case 0b11100000:
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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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goto ERROR;
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break;
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}
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ERROR:
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isr_state = 0x8000;
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recv_data = 0xFF00; // clear data and scancode of error 0x00
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ibmpc_error = 0xFF;
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return;
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DONE:
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// TODO: process error code: 0x00(AT), 0xFF(XT) in particular
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isr_state = 0x8000; // clear to next data
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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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ibmpc_host_send(0xED);
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ibmpc_host_send(led);
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}
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