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/*****************************************************************************
# #
# KVMD - The main PiKVM daemon. #
# #
# Copyright (C) 2018-2023 Maxim Devaev <[email protected]> #
# #
# This program is free software: you can redistribute it and/or modify #
# it under the terms of the GNU General Public License as published by #
# the Free Software Foundation, either version 3 of the License, or #
# (at your option) any later version. #
# #
# This program is distributed in the hope that it will be useful, #
# but WITHOUT ANY WARRANTY; without even the implied warranty of #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
# GNU General Public License for more details. #
# #
# You should have received a copy of the GNU General Public License #
# along with this program. If not, see <https://www.gnu.org/licenses/>. #
# #
*****************************************************************************/
#include "ph_spi.h"
#include "hardware/gpio.h"
#include "hardware/irq.h"
#include "hardware/spi.h"
#include "hardware/regs/spi.h"
#include "ph_types.h"
#define _BUS spi0
#define _IRQ SPI0_IRQ
#define _FREQ (2 * 1000 * 1000)
#define _CS_PIN 21
#define _RX_PIN 20
#define _TX_PIN 19
#define _CLK_PIN 18
static volatile u8 _in_buf[8] = {0};
static volatile u8 _in_index = 0;
static volatile u8 _out_buf[8] = {0};
static volatile u8 _out_index = 0;
static void (*_data_cb)(const u8 *) = NULL;
static void _xfer_isr(void);
void ph_spi_init(void (*data_cb)(const u8 *), void (*timeout_cb)(void)) {
_data_cb = data_cb;
(void)timeout_cb;
spi_init(_BUS, _FREQ);
spi_set_slave(_BUS, true);
spi_set_format(_BUS, 8, SPI_CPOL_0, SPI_CPHA_0, SPI_MSB_FIRST);
gpio_set_function(_CS_PIN, GPIO_FUNC_SPI);
gpio_set_function(_RX_PIN, GPIO_FUNC_SPI);
gpio_set_function(_TX_PIN, GPIO_FUNC_SPI);
gpio_set_function(_CLK_PIN, GPIO_FUNC_SPI);
// https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2040/hardware_regs/include/hardware/regs/spi.h
irq_set_exclusive_handler(_IRQ, _xfer_isr);
spi_get_hw(_BUS)->imsc = SPI_SSPIMSC_RXIM_BITS | SPI_SSPIMSC_TXIM_BITS;
irq_set_enabled(_IRQ, true);
}
void ph_spi_task(void) {
if (!_out_buf[0] && _in_index == 8) {
_data_cb((const u8 *)_in_buf);
}
}
void ph_spi_write(const u8 *data) {
// Меджик в нулевом байте разрешает начать ответ
for (s8 i = 7; i >= 0; --i) {
_out_buf[i] = data[i];
}
}
void __isr __not_in_flash_func(_xfer_isr)(void) {
# define SR (spi_get_hw(_BUS)->sr)
# define DR (spi_get_hw(_BUS)->dr)
while (SR & SPI_SSPSR_TNF_BITS) {
if (_out_buf[0] && _out_index < 8) {
DR = (u32)_out_buf[_out_index];
++_out_index;
if (_out_index == 8) {
_out_index = 0;
_in_index = 0;
_out_buf[0] = 0;
}
} else {
DR = (u32)0;
}
}
while (SR & SPI_SSPSR_RNE_BITS) {
static bool receiving = false;
const u8 in = DR;
if (!receiving && in != 0) {
receiving = true;
}
if (receiving && _in_index < 8) {
_in_buf[_in_index] = in;
++_in_index;
}
if (_in_index == 8) {
receiving = false;
}
}
# undef DR
# undef SR
}
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