diff options
Diffstat (limited to 'drivers/ps2/ps2_busywait.c')
| -rw-r--r-- | drivers/ps2/ps2_busywait.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/drivers/ps2/ps2_busywait.c b/drivers/ps2/ps2_busywait.c new file mode 100644 index 0000000000..983194eea8 --- /dev/null +++ b/drivers/ps2/ps2_busywait.c @@ -0,0 +1,187 @@ +/* +Copyright 2010,2011,2012,2013 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. +*/ + +/* + * PS/2 protocol busywait version + */ + +#include <stdbool.h> +#include "wait.h" +#include "ps2.h" +#include "ps2_io.h" +#include "debug.h" + +#define WAIT(stat, us, err) \ + do { \ + if (!wait_##stat(us)) { \ + ps2_error = err; \ + goto ERROR; \ + } \ + } while (0) + +uint8_t ps2_error = PS2_ERR_NONE; + +void ps2_host_init(void) { + clock_init(); + data_init(); + + // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20) + wait_ms(2500); + + inhibit(); +} + +uint8_t ps2_host_send(uint8_t data) { + bool parity = true; + ps2_error = PS2_ERR_NONE; + + /* terminate a transmission if we have */ + inhibit(); + wait_us(100); // 100us [4]p.13, [5]p.50 + + /* 'Request to Send' and Start bit */ + data_lo(); + clock_hi(); + WAIT(clock_lo, 10000, 10); // 10ms [5]p.50 + + /* Data bit */ + 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, 50, 6); + WAIT(clock_lo, 50, 7); + + /* wait for idle state */ + WAIT(clock_hi, 50, 8); + WAIT(data_hi, 50, 9); + + inhibit(); + return ps2_host_recv_response(); +ERROR: + inhibit(); + return 0; +} + +/* receive data when host want else inhibit communication */ +uint8_t ps2_host_recv_response(void) { + // Command may take 25ms/20ms at most([5]p.46, [3]p.21) + // 250 * 100us(wait for start bit in ps2_host_recv) + uint8_t data = 0; + uint8_t try + = 250; + do { + data = ps2_host_recv(); + } while (try --&&ps2_error); + return data; +} + +/* called after start bit comes */ +uint8_t ps2_host_recv(void) { + uint8_t data = 0; + bool parity = true; + ps2_error = PS2_ERR_NONE; + + /* release lines(idle state) */ + idle(); + + /* start bit [1] */ + WAIT(clock_lo, 100, 1); // TODO: this is enough? + WAIT(data_lo, 1, 2); + WAIT(clock_hi, 50, 3); + + /* data [2-9] */ + for (uint8_t i = 0; i < 8; i++) { + WAIT(clock_lo, 50, 4); + if (data_in()) { + parity = !parity; + data |= (1 << i); + } + WAIT(clock_hi, 50, 5); + } + + /* parity [10] */ + WAIT(clock_lo, 50, 6); + if (data_in() != parity) { + ps2_error = PS2_ERR_PARITY; + goto ERROR; + } + WAIT(clock_hi, 50, 7); + + /* stop bit [11] */ + WAIT(clock_lo, 50, 8); + WAIT(data_hi, 1, 9); + WAIT(clock_hi, 50, 10); + + inhibit(); + return data; +ERROR: + if (ps2_error > PS2_ERR_STARTBIT3) { + xprintf("x%02X\n", ps2_error); + } + inhibit(); + return 0; +} + +/* send LED state to keyboard */ +void ps2_host_set_led(uint8_t led) { + ps2_host_send(0xED); + ps2_host_send(led); +} |