RIOT/cpu/cc2538/periph/uart.c

/*
 * Copyright (C) 2014 Loci Controls Inc.
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @ingroup     driver_periph
 * @{
 *
 * @file        uart.c
 * @brief       Low-level UART driver implementation
 *
 * @author      Ian Martin <ian@locicontrols.com>
 *
 * @}
 */

#include <stddef.h>

#include "board.h"
#include "cpu.h"
#include "sched.h"
#include "thread.h"
#include "periph/uart.h"
#include "periph_conf.h"

/* guard file in case no UART device was specified */
#if UART_NUMOF

#undef BIT
#define BIT(n) ( 1 << (n) )

#define UART_WORD_LENGTH        8

enum {
    FIFO_LEVEL_1_8TH = 0,
    FIFO_LEVEL_2_8TH = 1,
    FIFO_LEVEL_4_8TH = 2,
    FIFO_LEVEL_6_8TH = 3,
    FIFO_LEVEL_7_8TH = 4,
};

/* Bit masks for the UART Masked Interrupt Status (MIS) Register: */
#define OEMIS BIT(10) /**< UART overrun error masked status */
#define BEMIS BIT( 9) /**< UART break error masked status */
#define FEMIS BIT( 7) /**< UART framing error masked status */
#define RTMIS BIT( 6) /**< UART RX time-out masked status */
#define RXMIS BIT( 4) /**< UART RX masked interrupt status */

#define UART_CTL_HSE_VALUE    0
#define DIVFRAC_NUM_BITS      6
#define DIVFRAC_MASK          ( (1 << DIVFRAC_NUM_BITS) - 1 )

/** @brief Indicates if there are bytes available in the UART0 receive FIFO */
#define uart0_rx_avail() ( UART0->FRbits.RXFE == 0 )

/** @brief Indicates if there are bytes available in the UART1 receive FIFO */
#define uart1_rx_avail() ( UART1->FRbits.RXFE == 0 )

/** @brief Read one byte from the UART0 receive FIFO */
#define uart0_read()     ( UART0->DR )

/** @brief Read one byte from the UART1 receive FIFO */
#define uart1_read()     ( UART1->DR )

/*---------------------------------------------------------------------------*/

/**
 * @brief Each UART device has to store two callbacks.
 */
typedef struct {
    uart_rx_cb_t rx_cb;
    uart_tx_cb_t tx_cb;
    void *arg;
} uart_conf_t;

/**
 * @brief Allocate memory to store the callback functions.
 */
static uart_conf_t uart_config[UART_NUMOF];

cc2538_uart_t * const UART0 = (cc2538_uart_t *)0x4000c000;
cc2538_uart_t * const UART1 = (cc2538_uart_t *)0x4000d000;

/*---------------------------------------------------------------------------*/
static void reset(cc2538_uart_t *u)
{
    /* Make sure the UART is disabled before trying to configure it */
    u->CTL = 0;

    u->CTLbits.RXE = 1;
    u->CTLbits.TXE = 1;
    u->CTLbits.HSE = UART_CTL_HSE_VALUE;

    /* Clear error status */
    u->ECR = 0xFF;

    /* Flush FIFOs by clearing LCHR.FEN */
    u->LCRHbits.FEN = 0;

    /* Restore LCHR configuration */
    u->LCRHbits.FEN = 1;

    /* UART Enable */
    u->CTLbits.UARTEN = 1;
}
/*---------------------------------------------------------------------------*/

#if UART_0_EN
__attribute__((naked))
void isr_uart0(void)
{
    uint_fast16_t mis;

    ISR_ENTER();
    asm("push {r4}");

    /* Store the current MIS and clear all flags early, except the RTM flag.
     * This will clear itself when we read out the entire FIFO contents */
    mis = UART_0_DEV->MIS;

    UART_0_DEV->ICR = 0x0000FFBF;

    while (UART_0_DEV->FRbits.RXFE == 0) {
        uart_config[0].rx_cb(uart_config[0].arg, UART_0_DEV->DR);
    }

    if (mis & (OEMIS | BEMIS | FEMIS)) {
        /* ISR triggered due to some error condition */
        reset(UART_0_DEV);
    }

    if (sched_context_switch_request) {
        thread_yield();
    }

    asm("pop {r4}");
    ISR_EXIT();
}
#endif /* UART_0_EN */

#if UART_1_EN
__attribute__((naked))
void isr_uart1(void)
{
    uint_fast16_t mis;

    ISR_ENTER();
    asm("push {r4}");

    /* Store the current MIS and clear all flags early, except the RTM flag.
     * This will clear itself when we read out the entire FIFO contents */
    mis = UART_1_DEV->MIS;

    UART_1_DEV->ICR = 0x0000FFBF;

    while (UART_1_DEV->FRbits.RXFE == 0) {
        uart_config[1].rx_cb(uart_config[1].arg, UART_1_DEV->DR);
    }

    if (mis & (OEMIS | BEMIS | FEMIS)) {
        /* ISR triggered due to some error condition */
        reset(UART_1_DEV);
    }

    if (sched_context_switch_request) {
        thread_yield();
    }

    asm("pop {r4}");
    ISR_EXIT();
}
#endif /* UART_1_EN */

int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, uart_tx_cb_t tx_cb, void *arg)
{
    /* initialize basic functionality */
    int res = uart_init_blocking(uart, baudrate);

    if (res != 0) {
        return res;
    }

    /* register callbacks */
    uart_config[uart].rx_cb = rx_cb;
    uart_config[uart].tx_cb = tx_cb;
    uart_config[uart].arg = arg;

    /* configure interrupts and enable RX interrupt */
    switch (uart) {
#if UART_0_EN
        case UART_0:
            NVIC_SetPriority(UART0_IRQn, UART_IRQ_PRIO);
            NVIC_EnableIRQ(UART0_IRQn);
            break;
#endif
#if UART_1_EN
        case UART_1:
            NVIC_SetPriority(UART1_IRQn, UART_IRQ_PRIO);
            NVIC_EnableIRQ(UART1_IRQn);
            break;
#endif
    }

    return 0;
}

int uart_init_blocking(uart_t uart, uint32_t baudrate)
{
    cc2538_uart_t *u;
    unsigned int uart_num;
    uint32_t divisor;

    switch (uart) {
#if UART_0_EN
        case UART_0:
            u = UART_0_DEV;

            /* Run on SYS_DIV */
            u->CC = 0;

            /*
             * Select the UARTx RX pin by writing to the IOC_UARTRXD_UARTn register
             */
            IOC_UARTRXD_UART0 = UART_0_RX_PIN;

            /*
             * Pad Control for the TX pin:
             * - Set function to UARTn TX
             * - Output Enable
             */
            IOC_PXX_SEL[UART_0_TX_PIN] = UART0_TXD;
            IOC_PXX_OVER[UART_0_TX_PIN] = IOC_OVERRIDE_OE;

            /* Set RX and TX pins to peripheral mode */
            gpio_hardware_control(UART_0_TX_PIN);
            gpio_hardware_control(UART_0_RX_PIN);
            break;
#endif
#if UART_1_EN
        case UART_1:
            u = UART_1_DEV;

            /* Run on SYS_DIV */
            u->CC = 0;

            /*
             * Select the UARTx RX pin by writing to the IOC_UARTRXD_UARTn register
             */
            IOC_UARTRXD_UART1 = UART_1_RX_PIN;

            /*
             * Pad Control for the TX pin:
             * - Set function to UARTn TX
             * - Output Enable
             */
            IOC_PXX_SEL[UART_1_TX_PIN] = UART1_TXD;
            IOC_PXX_OVER[UART_1_TX_PIN] = IOC_OVERRIDE_OE;

            /* Set RX and TX pins to peripheral mode */
            gpio_hardware_control(UART_1_TX_PIN);
            gpio_hardware_control(UART_1_RX_PIN);

#if ( defined(UART_1_RTS_PORT) && defined(UART_1_RTS_PIN) )
            IOC_PXX_SEL[UART_1_RTS_PIN] = UART1_RTS;
            gpio_hardware_control(UART_1_RTS_PIN);
            IOC_PXX_OVER[UART_1_RTS_PIN] = IOC_OVERRIDE_OE;
            u->CTLbits.RTSEN = 1;
#endif

#if ( defined(UART_1_CTS_PORT) && defined(UART_1_CTS_PIN) )
            IOC_UARTCTS_UART1 = UART_1_CTS_PIN;
            gpio_hardware_control(UART_1_CTS_PIN);
            IOC_PXX_OVER[UART_1_CTS_PIN] = IOC_OVERRIDE_DIS;
            u->CTLbits.CTSEN = 1;
#endif

            break;
#endif

        default:
            return -1;
    }

    /* Enable clock for the UART while Running, in Sleep and Deep Sleep */
    uart_num = ( (uintptr_t)u - (uintptr_t)UART0 ) / 0x1000;
    SYS_CTRL_RCGCUART |= (1 << uart_num);
    SYS_CTRL_SCGCUART |= (1 << uart_num);
    SYS_CTRL_DCGCUART |= (1 << uart_num);

    /*
     * UART Interrupt Masks:
     * Acknowledge RX and RX Timeout
     * Acknowledge Framing, Overrun and Break Errors
     */
    u->IM = 0;
    u->IMbits.RXIM = 1; /**< UART receive interrupt mask */
    u->IMbits.RTIM = 1; /**< UART receive time-out interrupt mask */
    u->IMbits.OEIM = 1; /**< UART overrun error interrupt mask */
    u->IMbits.BEIM = 1; /**< UART break error interrupt mask */
    u->IMbits.FEIM = 1; /**< UART framing error interrupt mask */

    /* Set FIFO interrupt levels: */
    u->IFLSbits.RXIFLSEL = FIFO_LEVEL_1_8TH;
    u->IFLSbits.TXIFLSEL = FIFO_LEVEL_4_8TH;

    /* Make sure the UART is disabled before trying to configure it */
    u->CTL = 0;

    u->CTLbits.RXE = 1;
    u->CTLbits.TXE = 1;
    u->CTLbits.HSE = UART_CTL_HSE_VALUE;

    /* Set the divisor for the baud rate generator */
    divisor = sys_clock_freq();
    divisor <<= UART_CTL_HSE_VALUE + 2;
    divisor /= baudrate;
    u->IBRD = divisor >> DIVFRAC_NUM_BITS;
    u->FBRD = divisor & DIVFRAC_MASK;

    /* Configure line control for 8-bit, no parity, 1 stop bit and enable  */
    u->LCRH = 0;
    u->LCRHbits.WLEN = UART_WORD_LENGTH - 5;
    u->LCRHbits.FEN  = 1;                    /**< Enable FIFOs */
    u->LCRHbits.PEN  = 0;                    /**< No parity */

    /* UART Enable */
    u->CTLbits.UARTEN = 1;

    return 0;
}

void uart_tx_begin(uart_t uart)
{

}

void uart_tx_end(uart_t uart)
{

}

int uart_write(uart_t uart, char data)
{
    cc2538_uart_t *u;

    switch (uart) {
#if UART_0_EN
        case UART_0:
            u = UART_0_DEV;
            break;
#endif
#if UART_1_EN
        case UART_1:
            u = UART_1_DEV;
            break;
#endif

        default:
            return -1;
    }

    if (u->FRbits.TXFF) {
        return 0;
    }

    u->DR = data;

    return 1;
}

int uart_read_blocking(uart_t uart, char *data)
{
    cc2538_uart_t *u;

    switch (uart) {
#if UART_0_EN
        case UART_0:
            u = UART_0_DEV;
            break;
#endif
#if UART_1_EN
        case UART_1:
            u = UART_1_DEV;
            break;
#endif

        default:
            return -1;
    }

    while (u->FRbits.RXFE);

    *data = u->DR;

    return 1;
}

int uart_write_blocking(uart_t uart, char data)
{
    cc2538_uart_t *u;

    switch (uart) {
#if UART_0_EN
        case UART_0:
            u = UART_0_DEV;
            break;
#endif
#if UART_1_EN
        case UART_1:
            u = UART_1_DEV;
            break;
#endif

        default:
            return -1;
    }

    /* Block if the TX FIFO is full */
    while (u->FRbits.TXFF);

    u->DR = data;

    return 1;
}

void uart_poweron(uart_t uart)
{

}

void uart_poweroff(uart_t uart)
{

}

#endif /* UART_NUMOF */