circuitpython/ports/raspberrypi/common-hal/busio/UART.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/busio/UART.h"

#include "mpconfigport.h"
#include "lib/utils/interrupt_char.h"
#include "py/gc.h"
#include "py/mperrno.h"
#include "py/runtime.h"
#include "py/stream.h"
#include "supervisor/shared/translate.h"
#include "supervisor/shared/tick.h"

#define UART_DEBUG(...) (void)0
// #define UART_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)

// Do-nothing callback needed so that usart_async code will enable rx interrupts.
// See comment below re usart_async_register_callback()
// static void usart_async_rxc_callback(const struct usart_async_descriptor *const descr) {
//     // Nothing needs to be done by us.
// }

#define NO_PIN 0xff

void common_hal_busio_uart_construct(busio_uart_obj_t *self,
    const mcu_pin_obj_t * tx, const mcu_pin_obj_t * rx,
    const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts,
    const mcu_pin_obj_t * rs485_dir, bool rs485_invert,
    uint32_t baudrate, uint8_t bits, busio_uart_parity_t parity, uint8_t stop,
    mp_float_t timeout, uint16_t receiver_buffer_size, byte* receiver_buffer,
    bool sigint_enabled) {
    mp_raise_NotImplementedError(translate("UART not yet supported"));

//     Sercom* sercom = NULL;
//     uint8_t sercom_index = 255; // Unset index
//     uint32_t rx_pinmux = 0;
//     uint8_t rx_pad = 255; // Unset pad
//     uint32_t tx_pinmux = 0;
//     uint8_t tx_pad = 255; // Unset pad

//     if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
//         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
//     }

//     if (bits > 8) {
//         mp_raise_NotImplementedError(translate("bytes > 8 bits not supported"));
//     }

//     bool have_tx = tx != NULL;
//     bool have_rx = rx != NULL;
//     if (!have_tx && !have_rx) {
//         mp_raise_ValueError(translate("tx and rx cannot both be None"));
//     }

//     self->baudrate = baudrate;
//     self->character_bits = bits;
//     self->timeout_ms = timeout * 1000;

//     // This assignment is only here because the usart_async routines take a *const argument.
//     struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;

//     for (int i = 0; i < NUM_SERCOMS_PER_PIN; i++) {
//         Sercom* potential_sercom = NULL;
//         if (have_tx) {
//             sercom_index = tx->sercom[i].index;
//             if (sercom_index >= SERCOM_INST_NUM) {
//                 continue;
//             }
//             potential_sercom = sercom_insts[sercom_index];
// #ifdef SAMD21
// 	    if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
//                 !(tx->sercom[i].pad == 0 ||
//                   tx->sercom[i].pad == 2)) {
//                 continue;
//             }
// #endif
// #ifdef SAM_D5X_E5X
// 	    if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
//                 !(tx->sercom[i].pad == 0)) {
//                 continue;
//             }
// #endif
//             tx_pinmux = PINMUX(tx->number, (i == 0) ? MUX_C : MUX_D);
//             tx_pad = tx->sercom[i].pad;
//             if (rx == NULL) {
//                 sercom = potential_sercom;
//                 break;
//             }
//         }
//         for (int j = 0; j < NUM_SERCOMS_PER_PIN; j++) {
//             if (((!have_tx && rx->sercom[j].index < SERCOM_INST_NUM &&
//                   sercom_insts[rx->sercom[j].index]->USART.CTRLA.bit.ENABLE == 0) ||
//                  sercom_index == rx->sercom[j].index) &&
//                 rx->sercom[j].pad != tx_pad) {
//                 rx_pinmux = PINMUX(rx->number, (j == 0) ? MUX_C : MUX_D);
//                 rx_pad = rx->sercom[j].pad;
//                 sercom = sercom_insts[rx->sercom[j].index];
//                 sercom_index = rx->sercom[j].index;
//                 break;
//             }
//         }
//         if (sercom != NULL) {
//             break;
//         }
//     }
//     if (sercom == NULL) {
//         mp_raise_ValueError(translate("Invalid pins"));
//     }
//     if (!have_tx) {
//         tx_pad = 0;
//         if (rx_pad == 0) {
//             tx_pad = 2;
//         }
//     }
//     if (!have_rx) {
//         rx_pad = (tx_pad + 1) % 4;
//     }

//     // Set up clocks on SERCOM.
//     samd_peripherals_sercom_clock_init(sercom, sercom_index);

//     if (rx && receiver_buffer_size > 0) {
//         self->buffer_length = receiver_buffer_size;
//         // Initially allocate the UART's buffer in the long-lived part of the
//         // heap.  UARTs are generally long-lived objects, but the "make long-
//         // lived" machinery is incapable of moving internal pointers like
//         // self->buffer, so do it manually.  (However, as long as internal
//         // pointers like this are NOT moved, allocating the buffer
//         // in the long-lived pool is not strictly necessary)
//         self->buffer = (uint8_t *) gc_alloc(self->buffer_length * sizeof(uint8_t), false, true);
//         if (self->buffer == NULL) {
//             common_hal_busio_uart_deinit(self);
//             mp_raise_msg_varg(&mp_type_MemoryError, translate("Failed to allocate RX buffer of %d bytes"), self->buffer_length * sizeof(uint8_t));
//         }
//     } else {
//         self->buffer_length = 0;
//         self->buffer = NULL;
//     }

//     if (usart_async_init(usart_desc_p, sercom, self->buffer, self->buffer_length, NULL) != ERR_NONE) {
//         mp_raise_ValueError(translate("Could not initialize UART"));
//     }

//     // usart_async_init() sets a number of defaults based on a prototypical SERCOM
//     // which don't necessarily match what we need. After calling it, set the values
//     // specific to this instantiation of UART.

//     // Set pads computed for this SERCOM.
//     // TXPO:
//     // 0x0: TX pad 0; no RTS/CTS
//     // 0x1: TX pad 2; no RTS/CTS
//     // 0x2: TX pad 0; RTS: pad 2, CTS: pad 3 (not used by us right now)
//     // So divide by 2 to map pad to value.
//     // RXPO:
//     // 0x0: RX pad 0
//     // 0x1: RX pad 1
//     // 0x2: RX pad 2
//     // 0x3: RX pad 3

//     // Doing a group mask and set of the registers saves 60 bytes over setting the bitfields individually.

//     sercom->USART.CTRLA.reg &= ~(SERCOM_USART_CTRLA_TXPO_Msk |
//                                  SERCOM_USART_CTRLA_RXPO_Msk |
//                                  SERCOM_USART_CTRLA_FORM_Msk);
//     sercom->USART.CTRLA.reg |= SERCOM_USART_CTRLA_TXPO(tx_pad / 2) |
//                                SERCOM_USART_CTRLA_RXPO(rx_pad) |
//                                (parity == BUSIO_UART_PARITY_NONE ? 0 : SERCOM_USART_CTRLA_FORM(1));

//     // Enable tx and/or rx based on whether the pins were specified.
//     // CHSIZE is 0 for 8 bits, 5, 6, 7 for 5, 6, 7 bits. 1 for 9 bits, but we don't support that.
//     sercom->USART.CTRLB.reg &= ~(SERCOM_USART_CTRLB_TXEN |
//                                  SERCOM_USART_CTRLB_RXEN |
//                                  SERCOM_USART_CTRLB_PMODE |
//                                  SERCOM_USART_CTRLB_SBMODE |
//                                  SERCOM_USART_CTRLB_CHSIZE_Msk);
//     sercom->USART.CTRLB.reg |= (have_tx ? SERCOM_USART_CTRLB_TXEN : 0) |
//                                (have_rx ? SERCOM_USART_CTRLB_RXEN : 0) |
//                                (parity == BUSIO_UART_PARITY_ODD ? SERCOM_USART_CTRLB_PMODE : 0) |
//                                (stop > 1 ? SERCOM_USART_CTRLB_SBMODE : 0) |
//                                SERCOM_USART_CTRLB_CHSIZE(bits % 8);

//     // Set baud rate
//     common_hal_busio_uart_set_baudrate(self, baudrate);

//     // Turn on rx interrupt handling. The UART async driver has its own set of internal callbacks,
//     // which are set up by uart_async_init(). These in turn can call user-specified callbacks.
//     // In fact, the actual interrupts are not enabled unless we set up a user-specified callback.
//     // This is confusing. It's explained in the Atmel START User Guide -> Implementation Description ->
//     // Different read function behavior in some asynchronous drivers. As of this writing:
//     // http://start.atmel.com/static/help/index.html?GUID-79201A5A-226F-4FBB-B0B8-AB0BE0554836
//     // Look at the ASFv4 code example for async USART.
//     usart_async_register_callback(usart_desc_p, USART_ASYNC_RXC_CB, usart_async_rxc_callback);


//     if (have_tx) {
//         gpio_set_pin_direction(tx->number, GPIO_DIRECTION_OUT);
//         gpio_set_pin_pull_mode(tx->number, GPIO_PULL_OFF);
//         gpio_set_pin_function(tx->number, tx_pinmux);
//         self->tx_pin  = tx->number;
//         claim_pin(tx);
//     } else {
//         self->tx_pin = NO_PIN;
//     }

//     if (have_rx) {
//         gpio_set_pin_direction(rx->number, GPIO_DIRECTION_IN);
//         gpio_set_pin_pull_mode(rx->number, GPIO_PULL_OFF);
//         gpio_set_pin_function(rx->number, rx_pinmux);
//         self->rx_pin  = rx->number;
//         claim_pin(rx);
//     } else {
//         self->rx_pin = NO_PIN;
//     }

//     usart_async_enable(usart_desc_p);
}

bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
    return self->rx_pin == NO_PIN && self->tx_pin == NO_PIN;
}

void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
    if (common_hal_busio_uart_deinited(self)) {
        return;
    }
    // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
    // usart_async_disable(usart_desc_p);
    // usart_async_deinit(usart_desc_p);
    reset_pin_number(self->rx_pin);
    reset_pin_number(self->tx_pin);
    self->rx_pin = NO_PIN;
    self->tx_pin = NO_PIN;
}

// Read characters.
size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t len, int *errcode) {
    if (self->rx_pin == NO_PIN) {
        mp_raise_ValueError(translate("No RX pin"));
    }

    // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;

    if (len == 0) {
        // Nothing to read.
        return 0;
    }

    // struct io_descriptor *io;
    // usart_async_get_io_descriptor(usart_desc_p, &io);

    size_t total_read = 0;
    // uint64_t start_ticks = supervisor_ticks_ms64();

    // // Busy-wait until timeout or until we've read enough chars.
    // while (supervisor_ticks_ms64() - start_ticks <= self->timeout_ms) {
    //     // Read as many chars as we can right now, up to len.
    //     size_t num_read = io_read(io, data, len);

    //     // Advance pointer in data buffer, and decrease how many chars left to read.
    //     data += num_read;
    //     len -= num_read;
    //     total_read += num_read;
    //     if (len == 0) {
    //         // Don't need to read any more: data buf is full.
    //         break;
    //     }
    //     if (num_read > 0) {
    //         // Reset the timeout on every character read.
    //         start_ticks = supervisor_ticks_ms64();
    //     }
    //     RUN_BACKGROUND_TASKS;
    //     // Allow user to break out of a timeout with a KeyboardInterrupt.
    //     if (mp_hal_is_interrupted()) {
    //         break;
    //     }
    //     // If we are zero timeout, make sure we don't loop again (in the event
    //     // we read in under 1ms)
    //     if (self->timeout_ms == 0) {
    //         break;
    //     }
    // }

    // if (total_read == 0) {
    //     *errcode = EAGAIN;
    //     return MP_STREAM_ERROR;
    // }

    return total_read;
}

// Write characters.
size_t common_hal_busio_uart_write(busio_uart_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
    if (self->tx_pin == NO_PIN) {
        mp_raise_ValueError(translate("No TX pin"));
    }

    // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;

    // struct io_descriptor *io;
    // usart_async_get_io_descriptor(usart_desc_p, &io);

    // // Start writing characters. This is non-blocking and will
    // // return immediately after setting up the write.
    // if (io_write(io, data, len) < 0) {
    //     *errcode = MP_EAGAIN;
    //     return MP_STREAM_ERROR;
    // }

    // // Busy-wait until all characters transmitted.
    // struct usart_async_status async_status;
    // while (true) {
    //     usart_async_get_status(usart_desc_p, &async_status);
    //     if (async_status.txcnt >= len) {
    //         break;
    //     }
    //     RUN_BACKGROUND_TASKS;
    // }

    return len;
}

uint32_t common_hal_busio_uart_get_baudrate(busio_uart_obj_t *self) {
    return self->baudrate;
}

void common_hal_busio_uart_set_baudrate(busio_uart_obj_t *self, uint32_t baudrate) {
    // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
    // usart_async_set_baud_rate(usart_desc_p,
    //                           // Samples and ARITHMETIC vs FRACTIONAL must correspond to USART_SAMPR in
    //                           // hpl_sercom_config.h.
    //                           _usart_async_calculate_baud_rate(baudrate,  // e.g. 9600 baud
    //                                                            PROTOTYPE_SERCOM_USART_ASYNC_CLOCK_FREQUENCY,
    //                                                            16,   // samples
    //                                                            USART_BAUDRATE_ASYNCH_ARITHMETIC,
    //                                                            0  // fraction - not used for ARITHMETIC
    //                                                            ));
    self->baudrate = baudrate;
}

mp_float_t common_hal_busio_uart_get_timeout(busio_uart_obj_t *self) {
    return (mp_float_t) (self->timeout_ms / 1000.0f);
}

void common_hal_busio_uart_set_timeout(busio_uart_obj_t *self, mp_float_t timeout) {
    self->timeout_ms = timeout * 1000;
}

uint32_t common_hal_busio_uart_rx_characters_available(busio_uart_obj_t *self) {
    // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
    // struct usart_async_status async_status;
    // usart_async_get_status(usart_desc_p, &async_status);
    // return async_status.rxcnt;
    return 0;
}

void common_hal_busio_uart_clear_rx_buffer(busio_uart_obj_t *self) {
    // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
    // usart_async_flush_rx_buffer(usart_desc_p);

}

// True if there are no characters still to be written.
bool common_hal_busio_uart_ready_to_tx(busio_uart_obj_t *self) {
    if (self->tx_pin == NO_PIN) {
        return false;
    }
    return false;
    // // This assignment is only here because the usart_async routines take a *const argument.
    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
    // struct usart_async_status async_status;
    // usart_async_get_status(usart_desc_p, &async_status);
    // return !(async_status.flags & USART_ASYNC_STATUS_BUSY);
}