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tmk_keyboard/tmk_core/protocol/ibmpc.c
tmk 22b6e87f37 ibmpc: Revert 2a0471fd on ibmpc_host_send() 
Restoring old recv_data can overwrite response data when the response is
multi-byte. This can happen when device responds with multiple bytes quickly,
for example Logitech MX518(PS/2) sends FA 00 in short period to F2 command
while most of devices doesn't send second byte that fast.

recv_data is cleared when calling ibmpc_host_send() you will have to
retain the data yourself before calling it. Or you have to make sure
that recv_data is empty as possible before calling the function.

Alternatively, ibmpc_host_send() can be changed to check if recv_data is
empty before seding command.
2021-06-22 00:33:40 +09:00

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/*
Copyright 2010,2011,2012,2013,2019 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.
*/
/*
* IBM PC keyboard protocol
*/
#include <stdbool.h>
#include <avr/interrupt.h>
#include <util/atomic.h>
#include "ibmpc.h"
#include "debug.h"
#include "timer.h"
#include "wait.h"
#define WAIT(stat, us, err) do { \
if (!wait_##stat(us)) { \
ibmpc_error = err; \
goto ERROR; \
} \
} while (0)
volatile uint16_t ibmpc_isr_debug = 0;
volatile uint8_t ibmpc_protocol = IBMPC_PROTOCOL_NO;
volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
/* 2-byte buffer for data received from keyboard
* buffer states:
* FFFF: empty
* FFss: one data
* sstt: two data
* eeFF: error
* where ss, tt and ee are 0x00-0xFE. 0xFF means empty or no data in buffer.
*/
static volatile uint16_t recv_data = 0xFFFF;
/* internal state of receiving data */
static volatile uint16_t isr_state = 0x8000;
static uint8_t timer_start = 0;
void ibmpc_host_init(void)
{
// initialize reset pin to HiZ
IBMPC_RST_HIZ();
inhibit();
IBMPC_INT_INIT();
IBMPC_INT_OFF();
}
void ibmpc_host_enable(void)
{
IBMPC_INT_ON();
idle();
}
void ibmpc_host_disable(void)
{
IBMPC_INT_OFF();
inhibit();
}
int16_t ibmpc_host_send(uint8_t data)
{
bool parity = true;
ibmpc_error = IBMPC_ERR_NONE;
uint8_t retry = 0;
dprintf("w%02X ", data);
// Not receiving data
if (isr_state != 0x8000) dprintf("isr:%04X ", isr_state);
while (isr_state != 0x8000) ;
// Not clock Lo
if (!clock_in()) dprintf("c:%u ", wait_clock_hi(1000));
// Not data Lo
if (!data_in()) dprintf("d:%u ", wait_data_hi(1000));
IBMPC_INT_OFF();
RETRY:
/* terminate a transmission if we have */
inhibit();
wait_us(200); // [5]p.54
/* 'Request to Send' and Start bit */
data_lo();
wait_us(200);
clock_hi(); // [5]p.54 [clock low]>100us [5]p.50
WAIT(clock_lo, 10000, 1); // [5]p.53, -10ms [5]p.50
/* Data bit[2-9] */
for (uint8_t i = 0; i < 8; i++) {
wait_us(15);
if (data&(1<<i)) {
parity = !parity;
data_hi();
} else {
data_lo();
}
WAIT(clock_hi, 50, 2);
WAIT(clock_lo, 50, 3);
}
/* Parity bit */
wait_us(15);
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_hi, 50, 4);
WAIT(clock_lo, 50, 5);
/* Stop bit */
wait_us(15);
data_hi();
/* Ack */
WAIT(data_lo, 300, 6);
WAIT(data_hi, 300, 7);
WAIT(clock_hi, 300, 8);
// clear buffer to get response correctly
ibmpc_host_isr_clear();
idle();
IBMPC_INT_ON();
return ibmpc_host_recv_response();
ERROR:
// Retry for Z-150 AT start bit error
if (ibmpc_error == 1 && retry++ < 10) {
ibmpc_error = IBMPC_ERR_NONE;
dprintf("R ");
goto RETRY;
}
ibmpc_error |= IBMPC_ERR_SEND;
inhibit();
wait_ms(2);
idle();
IBMPC_INT_ON();
return -1;
}
/*
* Receive data from keyboard
*/
int16_t ibmpc_host_recv(void)
{
uint16_t data = 0;
uint8_t ret = 0xFF;
ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
data = recv_data;
// remove data from buffer:
// FFFF(empty) -> FFFF
// FFss(one data) -> FFFF
// sstt(two data) -> FFtt
// eeFF(errror) -> FFFF
recv_data = data | (((data&0xFF00) == 0xFF00) ? 0x00FF : 0xFF00);
}
if ((data&0x00FF) == 0x00FF) {
// error: eeFF
switch (data>>8) {
case IBMPC_ERR_FF:
// 0xFF(Overrun/Error) from keyboard
dprintf("!FF! ");
ret = 0xFF;
break;
case IBMPC_ERR_FULL:
// buffer full
dprintf("!FULL! ");
ret = 0xFF;
break;
case 0xFF:
// empty: FFFF
return -1;
default:
// other errors
dprintf("e%02X ", data>>8);
return -1;
}
} else {
if ((data | 0x00FF) != 0xFFFF) {
// two data: sstt
dprintf("b:%04X ", data);
ret = (data>>8);
} else {
// one data: FFss
ret = (data&0x00FF);
}
}
//dprintf("i%04X ", ibmpc_isr_debug); ibmpc_isr_debug = 0;
dprintf("r%02X ", ret);
return ret;
}
int16_t ibmpc_host_recv_response(void)
{
// Command may take 25ms/20ms at most([5]p.46, [3]p.21)
uint8_t retry = 25;
int16_t data = -1;
while (retry-- && (data = ibmpc_host_recv()) == -1) {
wait_ms(1);
}
return data;
}
void ibmpc_host_isr_clear(void)
{
ibmpc_isr_debug = 0;
ibmpc_protocol = 0;
ibmpc_error = 0;
isr_state = 0x8000;
recv_data = 0xFFFF;
}
#define LO8(w) (*((uint8_t *)&(w)))
#define HI8(w) (*(((uint8_t *)&(w))+1))
// NOTE: With this ISR data line can be read within 2us after clock falling edge.
// To read data line early as possible:
// write naked ISR with asembly code to read the line and call C func to do other job?
ISR(IBMPC_INT_VECT)
{
uint8_t dbit;
dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
// Timeout check
uint8_t t;
// use only the least byte of millisecond timer
asm("lds %0, %1" : "=r" (t) : "p" (&timer_count));
//t = (uint8_t)timer_count; // compiler uses four registers instead of one
if (isr_state == 0x8000) {
timer_start = t;
} else {
// This gives 2.0ms at least before timeout
if ((uint8_t)(t - timer_start) >= 3) {
ibmpc_isr_debug = isr_state;
ibmpc_error = IBMPC_ERR_TIMEOUT;
goto ERROR;
// timeout error recovery - start receiving new data
// it seems to work somehow but may not under unstable situation
//timer_start = t;
//isr_state = 0x8000;
}
}
isr_state = isr_state>>1;
if (dbit) isr_state |= 0x8000;
// isr_state: state of receiving data from keyboard
//
// This should be initialized with 0x8000 before receiving data and
// the MSB '*1' works as marker to discrimitate between protocols.
// It stores sampled bit at MSB after right shift on each clock falling edge.
//
// XT protocol has two variants of signaling; XT_IBM and XT_Clone.
// XT_IBM uses two start bits 0 and 1 while XT_Clone uses just start bit 1.
// https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
//
// 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
// -----------------------------------------------------
// *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 Initial state(0x8000)
//
// x x x x x x x x | 0 0 0 0 0 0 0 0 midway(0-7 bits received)
// x x x x x x x x | *1 0 0 0 0 0 0 0 midway(8 bits received)
// b6 b5 b4 b3 b2 b1 b0 1 | 0 *1 0 0 0 0 0 0 XT_IBM-midway ^1
// b7 b6 b5 b4 b3 b2 b1 b0 | 0 *1 0 0 0 0 0 0 AT-midway ^1
// b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 XT_Clone-done ^3
// b6 b5 b4 b3 b2 b1 b0 1 | 1 *1 0 0 0 0 0 0 XT_IBM-error ^3
// pr b7 b6 b5 b4 b3 b2 b1 | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
// b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 XT_IBM-done ^2
// pr b7 b6 b5 b4 b3 b2 b1 | 1 0 *1 0 0 0 0 0 AT-midway[b0=1] ^2
// b7 b6 b5 b4 b3 b2 b1 b0 | 1 1 *1 0 0 0 0 0 XT_IBM-error-done
// x x x x x x x x | x 1 1 0 0 0 0 0 illegal
// st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 AT-done
// x x x x x x x x | x x 1 *1 0 0 0 0 illegal
// all other states than above illegal
//
// ^1: AT and XT_IBM takes same state.
// ^2: AT and XT_IBM takes same state in case that AT b0 is 1,
// we have to check AT stop bit to discriminate between the two protocol.
switch (isr_state & 0xFF) {
case 0b00000000:
case 0b10000000:
case 0b01000000: // ^1
case 0b00100000:
// midway
goto NEXT;
break;
case 0b11000000: // ^3
{
uint8_t us = 100;
// wait for rising and falling edge of b7 of XT_IBM
while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
if (us) {
// XT_IBM-error: read start(0) as 1
goto NEXT;
} else {
// XT_Clone-done
ibmpc_isr_debug = isr_state;
isr_state = isr_state>>8;
ibmpc_protocol = IBMPC_PROTOCOL_XT_CLONE;
goto DONE;
}
}
break;
case 0b11100000:
// XT_IBM-error-done
ibmpc_isr_debug = isr_state;
isr_state = isr_state>>8;
ibmpc_protocol = IBMPC_PROTOCOL_XT_ERROR;
goto DONE;
break;
case 0b10100000: // ^2
{
uint8_t us = 100;
// wait for rising and falling edge of AT stop bit to discriminate between XT and AT
while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
if (us) {
// found stop bit: AT-midway - process the stop bit in next ISR
goto NEXT;
} else {
// no stop bit: XT_IBM-done
ibmpc_isr_debug = isr_state;
isr_state = isr_state>>8;
ibmpc_protocol = IBMPC_PROTOCOL_XT_IBM;
goto DONE;
}
}
break;
case 0b00010000:
case 0b10010000:
case 0b01010000:
case 0b11010000:
// AT-done
// TODO: parity check?
ibmpc_isr_debug = isr_state;
// stop bit check
if (isr_state & 0x8000) {
ibmpc_protocol = IBMPC_PROTOCOL_AT;
} else {
// Zenith Z-150 AT(beige/white lable) asserts stop bit as low
// https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#zenith-z-150-beige
ibmpc_protocol = IBMPC_PROTOCOL_AT_Z150;
}
isr_state = isr_state>>6;
goto DONE;
break;
case 0b01100000:
case 0b00110000:
case 0b10110000:
case 0b01110000:
case 0b11110000:
default: // xxxx_oooo(any 1 in low nibble)
// Illegal
ibmpc_isr_debug = isr_state;
ibmpc_error = IBMPC_ERR_ILLEGAL;
goto ERROR;
break;
}
ERROR:
// error: eeFF
recv_data = (ibmpc_error<<8) | 0x00FF;
goto CLEAR;
DONE:
if ((isr_state & 0x00FF) == 0x00FF) {
// receive error code 0xFF
ibmpc_error = IBMPC_ERR_FF;
goto ERROR;
}
if (HI8(recv_data) != 0xFF && LO8(recv_data) != 0xFF) {
// buffer full
ibmpc_error = IBMPC_ERR_FULL;
goto ERROR;
}
// store data
recv_data = recv_data<<8;
recv_data |= isr_state & 0xFF;
CLEAR:
// clear for next data
isr_state = 0x8000;
NEXT:
return;
}
/* send LED state to keyboard */
void ibmpc_host_set_led(uint8_t led)
{
if (0xFA == ibmpc_host_send(0xED)) {
ibmpc_host_send(led);
}
}
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