148 lines
5.0 KiB
C
148 lines
5.0 KiB
C
/**
|
|
* Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
|
|
*
|
|
* SPDX-License-Identifier: BSD-3-Clause
|
|
*/
|
|
|
|
#include "pio_i2c.h"
|
|
|
|
const int PIO_I2C_ICOUNT_LSB = 10;
|
|
const int PIO_I2C_FINAL_LSB = 9;
|
|
const int PIO_I2C_DATA_LSB = 1;
|
|
const int PIO_I2C_NAK_LSB = 0;
|
|
|
|
|
|
bool pio_i2c_check_error(PIO pio, uint sm) {
|
|
return !!(pio->irq & (1u << sm));
|
|
}
|
|
|
|
void pio_i2c_resume_after_error(PIO pio, uint sm) {
|
|
pio_sm_drain_tx_fifo(pio, sm);
|
|
pio_sm_exec(pio, sm, (pio->sm[sm].execctrl & PIO_SM0_EXECCTRL_WRAP_BOTTOM_BITS) >> PIO_SM0_EXECCTRL_WRAP_BOTTOM_LSB);
|
|
pio->irq = 1u << sm;
|
|
}
|
|
|
|
void pio_i2c_rx_enable(PIO pio, uint sm, bool en) {
|
|
if (en)
|
|
hw_set_bits(&pio->sm[sm].shiftctrl, PIO_SM0_SHIFTCTRL_AUTOPUSH_BITS);
|
|
else
|
|
hw_clear_bits(&pio->sm[sm].shiftctrl, PIO_SM0_SHIFTCTRL_AUTOPUSH_BITS);
|
|
}
|
|
|
|
static inline void pio_i2c_put16(PIO pio, uint sm, uint16_t data) {
|
|
while (pio_sm_is_tx_fifo_full(pio, sm))
|
|
;
|
|
// some versions of GCC dislike this
|
|
#pragma GCC diagnostic push
|
|
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
|
|
*(io_rw_16 *)&pio->txf[sm] = data;
|
|
#pragma GCC diagnostic pop
|
|
}
|
|
|
|
|
|
// If I2C is ok, block and push data. Otherwise fall straight through.
|
|
void pio_i2c_put_or_err(PIO pio, uint sm, uint16_t data) {
|
|
while (pio_sm_is_tx_fifo_full(pio, sm))
|
|
if (pio_i2c_check_error(pio, sm))
|
|
return;
|
|
if (pio_i2c_check_error(pio, sm))
|
|
return;
|
|
// some versions of GCC dislike this
|
|
#pragma GCC diagnostic push
|
|
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
|
|
*(io_rw_16 *)&pio->txf[sm] = data;
|
|
#pragma GCC diagnostic pop
|
|
}
|
|
|
|
uint8_t pio_i2c_get(PIO pio, uint sm) {
|
|
return (uint8_t)pio_sm_get(pio, sm);
|
|
}
|
|
|
|
void pio_i2c_start(PIO pio, uint sm) {
|
|
pio_i2c_put_or_err(pio, sm, 1u << PIO_I2C_ICOUNT_LSB); // Escape code for 2 instruction sequence
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC1_SD0]); // We are already in idle state, just pull SDA low
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC0_SD0]); // Also pull clock low so we can present data
|
|
}
|
|
|
|
void pio_i2c_stop(PIO pio, uint sm) {
|
|
pio_i2c_put_or_err(pio, sm, 2u << PIO_I2C_ICOUNT_LSB);
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC0_SD0]); // SDA is unknown; pull it down
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC1_SD0]); // Release clock
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC1_SD1]); // Release SDA to return to idle state
|
|
};
|
|
|
|
void pio_i2c_repstart(PIO pio, uint sm) {
|
|
pio_i2c_put_or_err(pio, sm, 3u << PIO_I2C_ICOUNT_LSB);
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC0_SD1]);
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC1_SD1]);
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC1_SD0]);
|
|
pio_i2c_put_or_err(pio, sm, set_scl_sda_program_instructions[I2C_SC0_SD0]);
|
|
}
|
|
|
|
static void pio_i2c_wait_idle(PIO pio, uint sm) {
|
|
// Finished when TX runs dry or SM hits an IRQ
|
|
pio->fdebug = 1u << (PIO_FDEBUG_TXSTALL_LSB + sm);
|
|
while (!(pio->fdebug & 1u << (PIO_FDEBUG_TXSTALL_LSB + sm) || pio_i2c_check_error(pio, sm)))
|
|
tight_loop_contents();
|
|
}
|
|
|
|
int pio_i2c_write_blocking(PIO pio, uint sm, uint8_t addr, uint8_t *txbuf, uint len) {
|
|
int err = 0;
|
|
pio_i2c_start(pio, sm);
|
|
pio_i2c_rx_enable(pio, sm, false);
|
|
pio_i2c_put16(pio, sm, (addr << 2) | 1u);
|
|
while (len && !pio_i2c_check_error(pio, sm)) {
|
|
if (!pio_sm_is_tx_fifo_full(pio, sm)) {
|
|
--len;
|
|
pio_i2c_put_or_err(pio, sm, (*txbuf++ << PIO_I2C_DATA_LSB) | ((len == 0) << PIO_I2C_FINAL_LSB) | 1u);
|
|
}
|
|
}
|
|
pio_i2c_stop(pio, sm);
|
|
pio_i2c_wait_idle(pio, sm);
|
|
if (pio_i2c_check_error(pio, sm)) {
|
|
err = -1;
|
|
pio_i2c_resume_after_error(pio, sm);
|
|
pio_i2c_stop(pio, sm);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
int pio_i2c_read_blocking(PIO pio, uint sm, uint8_t addr, uint8_t *rxbuf, uint len) {
|
|
int err = 0;
|
|
pio_i2c_start(pio, sm);
|
|
pio_i2c_rx_enable(pio, sm, true);
|
|
while (!pio_sm_is_rx_fifo_empty(pio, sm))
|
|
(void)pio_i2c_get(pio, sm);
|
|
pio_i2c_put16(pio, sm, (addr << 2) | 3u);
|
|
uint32_t tx_remain = len; // Need to stuff 0xff bytes in to get clocks
|
|
|
|
bool first = true;
|
|
|
|
while ((tx_remain || len) && !pio_i2c_check_error(pio, sm)) {
|
|
if (tx_remain && !pio_sm_is_tx_fifo_full(pio, sm)) {
|
|
--tx_remain;
|
|
pio_i2c_put16(pio, sm, (0xffu << 1) | (tx_remain ? 0 : (1u << PIO_I2C_FINAL_LSB) | (1u << PIO_I2C_NAK_LSB)));
|
|
}
|
|
if (!pio_sm_is_rx_fifo_empty(pio, sm)) {
|
|
if (first) {
|
|
// Ignore returned address byte
|
|
(void)pio_i2c_get(pio, sm);
|
|
first = false;
|
|
}
|
|
else {
|
|
--len;
|
|
*rxbuf++ = pio_i2c_get(pio, sm);
|
|
}
|
|
}
|
|
}
|
|
pio_i2c_stop(pio, sm);
|
|
pio_i2c_wait_idle(pio, sm);
|
|
if (pio_i2c_check_error(pio, sm)) {
|
|
err = -1;
|
|
pio_i2c_resume_after_error(pio, sm);
|
|
pio_i2c_stop(pio, sm);
|
|
}
|
|
return err;
|
|
}
|
|
|