src/rp2_common/hardware_pio/pio.c

/*
 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include "hardware/claim.h"
#include "hardware/pio.h"
#include "hardware/pio_instructions.h"

// sanity check
check_hw_layout(pio_hw_t, sm[0].clkdiv, PIO_SM0_CLKDIV_OFFSET);
check_hw_layout(pio_hw_t, sm[1].clkdiv, PIO_SM1_CLKDIV_OFFSET);
check_hw_layout(pio_hw_t, instr_mem[0], PIO_INSTR_MEM0_OFFSET);
check_hw_layout(pio_hw_t, inte0, PIO_IRQ0_INTE_OFFSET);
check_hw_layout(pio_hw_t, txf[1], PIO_TXF1_OFFSET);
check_hw_layout(pio_hw_t, rxf[3], PIO_RXF3_OFFSET);
check_hw_layout(pio_hw_t, ints1, PIO_IRQ1_INTS_OFFSET);

static_assert(NUM_PIO_STATE_MACHINES * NUM_PIOS <= 8, "");
static uint8_t claimed;

void pio_sm_claim(PIO pio, uint sm) {
    check_sm_param(sm);
    uint which = pio_get_index(pio);
    if (which) {
        hw_claim_or_assert(&claimed, NUM_PIO_STATE_MACHINES + sm, "PIO 1 SM %d already claimed");
    } else {
        hw_claim_or_assert(&claimed, sm, "PIO 0 SM %d already claimed");
    }
}

void pio_claim_sm_mask(PIO pio, uint sm_mask) {
    for(uint i = 0; sm_mask; i++, sm_mask >>= 1u) {
        if (sm_mask & 1u) pio_sm_claim(pio, i);
    }
}
void pio_sm_unclaim(PIO pio, uint sm) {
    check_sm_param(sm);
    uint which = pio_get_index(pio);
    hw_claim_clear(&claimed, which * NUM_PIO_STATE_MACHINES + sm);
}

int pio_claim_unused_sm(PIO pio, bool required) {
    uint which = pio_get_index(pio);
    uint base = which * NUM_PIO_STATE_MACHINES;
    int index = hw_claim_unused_from_range((uint8_t*)&claimed, required, base,
                                      base + NUM_PIO_STATE_MACHINES - 1, "No PIO state machines are available");
    return index >= base ? index - base : -1;
}

void pio_load_program(PIO pio, const uint16_t *prog, uint8_t prog_len, uint8_t load_offset) {
    // instructions are only 16 bits, but instruction memory locations are spaced 32 bits apart
    // Adjust the addresses of any jump instructions to respect load offset
    assert(load_offset + prog_len <= PIO_INSTRUCTION_COUNT);

}

static_assert(PIO_INSTRUCTION_COUNT <= 32, "");
static uint32_t _used_instruction_space[2];

static int _pio_find_offset_for_program(PIO pio, const pio_program_t *program) {
    assert(program->length < PIO_INSTRUCTION_COUNT);
    uint32_t used_mask = _used_instruction_space[pio_get_index(pio)];
    uint32_t program_mask = (1u << program->length) - 1;
    if (program->origin >= 0) {
        if (program->origin > 32 - program->length) return -1;
        return used_mask & (program_mask << program->origin) ? -1 : program->origin;
    } else {
        // work down from the top always
        for (int i = 32 - program->length; i >= 0; i--) {
            if (!(used_mask & (program_mask << (uint) i))) {
                return i;
            }
        }
        return -1;
    }
}

bool pio_can_add_program(PIO pio, const pio_program_t *program) {
    uint32_t save = hw_claim_lock();
    bool rc =  -1 != _pio_find_offset_for_program(pio, program);
    hw_claim_unlock(save);
    return rc;
}

static bool _pio_can_add_program_at_offset(PIO pio, const pio_program_t *program, uint offset) {
    assert(offset < PIO_INSTRUCTION_COUNT);
    assert(offset + program->length <= PIO_INSTRUCTION_COUNT);
    if (program->origin >= 0 && program->origin != offset) return false;
    uint32_t used_mask = _used_instruction_space[pio_get_index(pio)];
    uint32_t program_mask = (1u << program->length) - 1;
    return !(used_mask & (program_mask << offset));
}

bool pio_can_add_program_at_offset(PIO pio, const pio_program_t *program, uint offset) {
    uint32_t save = hw_claim_lock();
    bool rc = _pio_can_add_program_at_offset(pio, program, offset);
    hw_claim_unlock(save);
    return rc;
}

static void _pio_add_program_at_offset(PIO pio, const pio_program_t *program, uint offset) {
    if (!_pio_can_add_program_at_offset(pio, program, offset)) {
        panic("No program space");
    }
    for (uint i = 0; i < program->length; ++i) {
        uint16_t instr = program->instructions[i];
        pio->instr_mem[offset + i] = pio_instr_bits_jmp != _pio_major_instr_bits(instr) ? instr : instr + offset;
    }
    uint32_t program_mask = (1u << program->length) - 1;
    _used_instruction_space[pio_get_index(pio)] |= program_mask << offset;
}

// these assert if unable
uint pio_add_program(PIO pio, const pio_program_t *program) {
    uint32_t save = hw_claim_lock();
    int offset = _pio_find_offset_for_program(pio, program);
    if (offset < 0) {
        panic("No program space");
    }
    _pio_add_program_at_offset(pio, program, offset);
    hw_claim_unlock(save);
    return offset;
}

void pio_remove_program(PIO pio, const pio_program_t *program, uint loaded_offset) {
    uint32_t program_mask = (1u << program->length) - 1;
    program_mask <<= loaded_offset;
    uint32_t save = hw_claim_lock();
    assert(program_mask == (_used_instruction_space[pio_get_index(pio)] & program_mask));
    _used_instruction_space[pio_get_index(pio)] &= ~program_mask;
    hw_claim_unlock(save);
}

void pio_clear_instruction_memory(PIO pio) {
    uint32_t save = hw_claim_lock();
    _used_instruction_space[pio_get_index(pio)] = 0;
    for(uint i=0;i<PIO_INSTRUCTION_COUNT;i++) {
        pio->instr_mem[i] = pio_encode_jmp(i);
    }
    hw_claim_unlock(save);
}

// Set the value of all PIO pins. This is done by forcibly executing
// instructions on a "victim" state machine, sm. Ideally you should choose one
// which is not currently running a program. This is intended for one-time
// setup of initial pin states.
void pio_sm_set_pins(PIO pio, uint sm, uint32_t pins) {
    uint32_t pinctrl_saved = pio->sm[sm].pinctrl;
    uint remaining = 32;
    uint base = 0;
    while (remaining) {
        uint decrement = remaining > 5 ? 5 : remaining;
        pio->sm[sm].pinctrl =
                (decrement << PIO_SM0_PINCTRL_SET_COUNT_LSB) |
                (base << PIO_SM0_PINCTRL_SET_BASE_LSB);
        pio_sm_exec(pio, sm, pio_encode_set(pio_pins, pins & 0x1fu));
        remaining -= decrement;
        base += decrement;
        pins >>= 5;
    }
    pio->sm[sm].pinctrl = pinctrl_saved;
}

void pio_sm_set_pins_with_mask(PIO pio, uint sm, uint32_t pinvals, uint32_t pin_mask) {
    uint32_t pinctrl_saved = pio->sm[sm].pinctrl;
    while (pin_mask) {
        uint base = __builtin_ctz(pin_mask);
        pio->sm[sm].pinctrl =
                (1u << PIO_SM0_PINCTRL_SET_COUNT_LSB) |
                (base << PIO_SM0_PINCTRL_SET_BASE_LSB);
        pio_sm_exec(pio, sm, pio_encode_set(pio_pins, (pinvals >> base) & 0x1u));
        pin_mask &= pin_mask - 1;
    }
    pio->sm[sm].pinctrl = pinctrl_saved;
}

void pio_sm_set_pindirs_with_mask(PIO pio, uint sm, uint32_t pindirs, uint32_t pin_mask) {
    uint32_t pinctrl_saved = pio->sm[sm].pinctrl;
    while (pin_mask) {
        uint base = __builtin_ctz(pin_mask);
        pio->sm[sm].pinctrl =
                (1u << PIO_SM0_PINCTRL_SET_COUNT_LSB) |
                (base << PIO_SM0_PINCTRL_SET_BASE_LSB);
        pio_sm_exec(pio, sm, pio_encode_set(pio_pindirs, (pindirs >> base) & 0x1u));
        pin_mask &= pin_mask - 1;
    }
    pio->sm[sm].pinctrl = pinctrl_saved;
}

void pio_sm_set_consecutive_pindirs(PIO pio, uint sm, uint pin, uint count, bool is_out) {
    assert(pin < 32u);
    uint32_t pinctrl_saved = pio->sm[sm].pinctrl;
    uint pindir_val = is_out ? 0x1f : 0;
    while (count > 5) {
        pio->sm[sm].pinctrl = (5u << PIO_SM0_PINCTRL_SET_COUNT_LSB) | (pin << PIO_SM0_PINCTRL_SET_BASE_LSB);
        pio_sm_exec(pio, sm, pio_encode_set(pio_pindirs, pindir_val));
        count -= 5;
        pin = (pin + 5) & 0x1f;
    }
    pio->sm[sm].pinctrl = (count << PIO_SM0_PINCTRL_SET_COUNT_LSB) | (pin << PIO_SM0_PINCTRL_SET_BASE_LSB);
    pio_sm_exec(pio, sm, pio_encode_set(pio_pindirs, pindir_val));
    pio->sm[sm].pinctrl = pinctrl_saved;
}

void pio_sm_init(PIO pio, uint sm, uint initial_pc, const pio_sm_config *config) {
    // Halt the machine, set some sensible defaults
    pio_sm_set_enabled(pio, sm, false);

    if (config) {
        pio_sm_set_config(pio, sm, config);
    } else {
        pio_sm_config c = pio_get_default_sm_config();
        pio_sm_set_config(pio, sm, &c);
    }

    pio_sm_clear_fifos(pio, sm);

    // Clear FIFO debug flags
    const uint32_t fdebug_sm_mask =
            (1u << PIO_FDEBUG_TXOVER_LSB) |
            (1u << PIO_FDEBUG_RXUNDER_LSB) |
            (1u << PIO_FDEBUG_TXSTALL_LSB) |
            (1u << PIO_FDEBUG_RXSTALL_LSB);
    pio->fdebug = fdebug_sm_mask << sm;

    // Finally, clear some internal SM state
    pio_sm_restart(pio, sm);
    pio_sm_clkdiv_restart(pio, sm);
    pio_sm_exec(pio, sm, pio_encode_jmp(initial_pc));
}

void pio_sm_drain_tx_fifo(PIO pio, uint sm) {
    uint instr = (pio->sm[sm].shiftctrl & PIO_SM0_SHIFTCTRL_AUTOPULL_BITS) ? pio_encode_out(pio_null, 32) :
                 pio_encode_pull(false, false);
    while (!pio_sm_is_tx_fifo_empty(pio, sm)) {
        pio_sm_exec(pio, sm, instr);
    }
}