LibrePilot/flight/pios/stm32f0x/pios_usart.c

/**
 ******************************************************************************
 * @addtogroup PIOS PIOS Core hardware abstraction layer
 * @{
 * @addtogroup   PIOS_USART USART Functions
 * @brief PIOS interface for USART port
 * @{
 *
 * @file       pios_usart.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      USART commands. Inits USARTs, controls USARTs & Interupt handlers. (STM32 dependent)
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * 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, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "pios.h"

#ifdef PIOS_INCLUDE_USART

#include <pios_usart_priv.h>

/* Provide a COM driver */
static void PIOS_USART_ChangeBaud(uint32_t usart_id, uint32_t baud);
static void PIOS_USART_RegisterRxCallback(uint32_t usart_id, pios_com_callback rx_in_cb, uint32_t context);
static void PIOS_USART_RegisterTxCallback(uint32_t usart_id, pios_com_callback tx_out_cb, uint32_t context);
static void PIOS_USART_TxStart(uint32_t usart_id, uint16_t tx_bytes_avail);
static void PIOS_USART_RxStart(uint32_t usart_id, uint16_t rx_bytes_avail);

const struct pios_com_driver pios_usart_com_driver = {
    .set_baud   = PIOS_USART_ChangeBaud,
    .tx_start   = PIOS_USART_TxStart,
    .rx_start   = PIOS_USART_RxStart,
    .bind_tx_cb = PIOS_USART_RegisterTxCallback,
    .bind_rx_cb = PIOS_USART_RegisterRxCallback,
};

enum pios_usart_dev_magic {
    PIOS_USART_DEV_MAGIC = 0x11223344,
};

struct pios_usart_dev {
    enum pios_usart_dev_magic   magic;
    const struct pios_usart_cfg *cfg;

    pios_com_callback rx_in_cb;
    uint32_t rx_in_context;
    pios_com_callback tx_out_cb;
    uint32_t tx_out_context;

    uint32_t rx_dropped;
};

static bool PIOS_USART_validate(struct pios_usart_dev *usart_dev)
{
    return usart_dev->magic == PIOS_USART_DEV_MAGIC;
}

#if defined(PIOS_INCLUDE_FREERTOS)
static struct pios_usart_dev *PIOS_USART_alloc(void)
{
    struct pios_usart_dev *usart_dev;

    usart_dev = (struct pios_usart_dev *)pvPortMalloc(sizeof(struct pios_usart_dev));
    if (!usart_dev) {
        return NULL;
    }

    memset(usart_dev, 0, sizeof(struct pios_usart_dev));
    usart_dev->magic = PIOS_USART_DEV_MAGIC;
    return usart_dev;
}
#else
static struct pios_usart_dev pios_usart_devs[PIOS_USART_MAX_DEVS];
static uint8_t pios_usart_num_devs;
static struct pios_usart_dev *PIOS_USART_alloc(void)
{
    struct pios_usart_dev *usart_dev;

    if (pios_usart_num_devs >= PIOS_USART_MAX_DEVS) {
        return NULL;
    }

    usart_dev = &pios_usart_devs[pios_usart_num_devs++];

    memset(usart_dev, 0, sizeof(struct pios_usart_dev));
    usart_dev->magic = PIOS_USART_DEV_MAGIC;

    return usart_dev;
}
#endif /* if defined(PIOS_INCLUDE_FREERTOS) */

/* Bind Interrupt Handlers
 *
 * Map all valid USART IRQs to the common interrupt handler
 * and provide storage for a 32-bit device id IRQ to map
 * each physical IRQ to a specific registered device instance.
 */
static void PIOS_USART_generic_irq_handler(uint32_t usart_id);

static uint32_t PIOS_USART_1_id;
void USART1_IRQHandler(void) __attribute__((alias("PIOS_USART_1_irq_handler")));
static void PIOS_USART_1_irq_handler(void)
{
    PIOS_USART_generic_irq_handler(PIOS_USART_1_id);
}

static uint32_t PIOS_USART_2_id;
void USART2_IRQHandler(void) __attribute__((alias("PIOS_USART_2_irq_handler")));
static void PIOS_USART_2_irq_handler(void)
{
    PIOS_USART_generic_irq_handler(PIOS_USART_2_id);
}

static uint32_t PIOS_USART_3_id;
void USART3_IRQHandler(void) __attribute__((alias("PIOS_USART_3_irq_handler")));
static void PIOS_USART_3_irq_handler(void)
{
    PIOS_USART_generic_irq_handler(PIOS_USART_3_id);
}

/**
 * Initialise a single USART device
 */
int32_t PIOS_USART_Init(uint32_t *usart_id, const struct pios_usart_cfg *cfg)
{
    PIOS_DEBUG_Assert(usart_id);
    PIOS_DEBUG_Assert(cfg);

    struct pios_usart_dev *usart_dev;

    usart_dev = (struct pios_usart_dev *)PIOS_USART_alloc();
    if (!usart_dev) {
        goto out_fail;
    }

    /* Bind the configuration to the device instance */
    usart_dev->cfg = cfg;

    /* Enable the USART Pins Software Remapping */
    if (usart_dev->cfg->remap) {
        GPIO_PinAFConfig(usart_dev->cfg->rx.gpio,
                         __builtin_ctz(usart_dev->cfg->rx.init.GPIO_Pin),
                         usart_dev->cfg->remap);
        GPIO_PinAFConfig(usart_dev->cfg->tx.gpio,
                         __builtin_ctz(usart_dev->cfg->tx.init.GPIO_Pin),
                         usart_dev->cfg->remap);
    }

    /* Initialize the USART Rx and Tx pins */
    GPIO_Init(usart_dev->cfg->rx.gpio, (GPIO_InitTypeDef*)&usart_dev->cfg->rx.init);
    GPIO_Init(usart_dev->cfg->tx.gpio, (GPIO_InitTypeDef*)&usart_dev->cfg->tx.init);

    /* Enable USART clock */
    switch ((uint32_t)usart_dev->cfg->regs) {
    case (uint32_t)USART1:
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
        break;
    case (uint32_t)USART2:
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
        break;
    case (uint32_t)USART3:
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
        break;
    }

    /* Configure the USART */
    USART_Init(usart_dev->cfg->regs, (USART_InitTypeDef*)&usart_dev->cfg->init);

    *usart_id = (uint32_t)usart_dev;

    /* Configure USART Interrupts */
    switch ((uint32_t)usart_dev->cfg->regs) {
    case (uint32_t)USART1:
        PIOS_USART_1_id = (uint32_t)usart_dev;
        break;
    case (uint32_t)USART2:
        PIOS_USART_2_id = (uint32_t)usart_dev;
        break;
    case (uint32_t)USART3:
        PIOS_USART_3_id = (uint32_t)usart_dev;
        break;
    }
    NVIC_Init((NVIC_InitTypeDef*)&usart_dev->cfg->irq.init);
    USART_ITConfig(usart_dev->cfg->regs, USART_IT_RXNE, ENABLE);
    USART_ITConfig(usart_dev->cfg->regs, USART_IT_TXE, ENABLE);

    /* Enable USART */
    USART_Cmd(usart_dev->cfg->regs, ENABLE);

    return 0;

out_fail:
    return -1;
}

static void PIOS_USART_RxStart(uint32_t usart_id, __attribute__((unused)) uint16_t rx_bytes_avail)
{
    struct pios_usart_dev *usart_dev = (struct pios_usart_dev *)usart_id;

    bool valid = PIOS_USART_validate(usart_dev);

    PIOS_Assert(valid);

    USART_ITConfig(usart_dev->cfg->regs, USART_IT_RXNE, ENABLE);
}
static void PIOS_USART_TxStart(uint32_t usart_id, __attribute__((unused)) uint16_t tx_bytes_avail)
{
    struct pios_usart_dev *usart_dev = (struct pios_usart_dev *)usart_id;

    bool valid = PIOS_USART_validate(usart_dev);

    PIOS_Assert(valid);

    USART_ITConfig(usart_dev->cfg->regs, USART_IT_TXE, ENABLE);
}

/**
 * Changes the baud rate of the USART peripheral without re-initialising.
 * \param[in] usart_id USART name (GPS, TELEM, AUX)
 * \param[in] baud Requested baud rate
 */
static void PIOS_USART_ChangeBaud(uint32_t usart_id, uint32_t baud)
{
    struct pios_usart_dev *usart_dev = (struct pios_usart_dev *)usart_id;

    bool valid = PIOS_USART_validate(usart_dev);

    PIOS_Assert(valid);

    USART_InitTypeDef USART_InitStructure;

    /* Start with a copy of the default configuration for the peripheral */
    USART_InitStructure = usart_dev->cfg->init;

    /* Adjust the baud rate */
    USART_InitStructure.USART_BaudRate = baud;

    /* Write back the new configuration */
    USART_Init(usart_dev->cfg->regs, &USART_InitStructure);
}

static void PIOS_USART_RegisterRxCallback(uint32_t usart_id, pios_com_callback rx_in_cb, uint32_t context)
{
    struct pios_usart_dev *usart_dev = (struct pios_usart_dev *)usart_id;

    bool valid = PIOS_USART_validate(usart_dev);

    PIOS_Assert(valid);

    /*
     * Order is important in these assignments since ISR uses _cb
     * field to determine if it's ok to dereference _cb and _context
     */
    usart_dev->rx_in_context = context;
    usart_dev->rx_in_cb = rx_in_cb;
}

static void PIOS_USART_RegisterTxCallback(uint32_t usart_id, pios_com_callback tx_out_cb, uint32_t context)
{
    struct pios_usart_dev *usart_dev = (struct pios_usart_dev *)usart_id;

    bool valid = PIOS_USART_validate(usart_dev);

    PIOS_Assert(valid);

    /*
     * Order is important in these assignments since ISR uses _cb
     * field to determine if it's ok to dereference _cb and _context
     */
    usart_dev->tx_out_context = context;
    usart_dev->tx_out_cb = tx_out_cb;
}

static void PIOS_USART_generic_irq_handler(uint32_t usart_id)
{
    struct pios_usart_dev *usart_dev = (struct pios_usart_dev *)usart_id;

    bool valid = PIOS_USART_validate(usart_dev);

    PIOS_Assert(valid);

    /* Force read of dr after sr to make sure to clear error flags */
    volatile uint16_t sr = usart_dev->cfg->regs->ISR;
    volatile uint8_t dr  = usart_dev->cfg->regs->RDR;

    /* Check if RXNE flag is set */
    bool rx_need_yield   = false;
    if (sr & USART_ISR_RXNE) {
        uint8_t byte = dr;
        if (usart_dev->rx_in_cb) {
            uint16_t rc;
            rc = (usart_dev->rx_in_cb)(usart_dev->rx_in_context, &byte, 1, NULL, &rx_need_yield);
            if (rc < 1) {
                /* Lost bytes on rx */
                usart_dev->rx_dropped += 1;
            }
        }
    }

    /* Check if TXE flag is set */
    bool tx_need_yield = false;
    if (sr & USART_ISR_TXE) {
        if (usart_dev->tx_out_cb) {
            uint8_t b;
            uint16_t bytes_to_send;

            bytes_to_send = (usart_dev->tx_out_cb)(usart_dev->tx_out_context, &b, 1, NULL, &tx_need_yield);

            if (bytes_to_send > 0) {
                /* Send the byte we've been given */
                usart_dev->cfg->regs->TDR = b;
            } else {
                /* No bytes to send, disable TXE interrupt */
                USART_ITConfig(usart_dev->cfg->regs, USART_IT_TXE, DISABLE);
            }
        } else {
            /* No bytes to send, disable TXE interrupt */
            USART_ITConfig(usart_dev->cfg->regs, USART_IT_TXE, DISABLE);
        }
    }

#if defined(PIOS_INCLUDE_FREERTOS)
    if (rx_need_yield || tx_need_yield) {
        vPortYield();
    }
#endif /* PIOS_INCLUDE_FREERTOS */
}

#endif /* PIOS_INCLUDE_USART */

/**
 * @}
 * @}
 */