source: mainline/kernel/genarch/src/drivers/am335x/uart.c@ 954b6458

/*
 * Copyright (c) 2012 Jan Vesely
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/** @addtogroup genarch
 * @{
 */
/**
 * @file
 * @brief Texas Instruments AM335x on-chip uart serial line driver.
 */

#include <genarch/drivers/am335x/uart.h>
#include <ddi/device.h>
#include <str.h>
#include <mm/km.h>

static void am335x_uart_txb(am335x_uart_t *uart, uint8_t b)
{
        /* Wait for buffer */
        while (uart->regs->ssr & AM335x_UART_SSR_TX_FIFO_FULL_FLAG);
        /* Write to the outgoing fifo */
        uart->regs->thr = b;
}

static void am335x_uart_putchar(outdev_t *dev, wchar_t ch)
{
        am335x_uart_t *uart = dev->data;
        if (!ascii_check(ch)) {
                am335x_uart_txb(uart, U_SPECIAL);
        } else {
                if (ch == '\n')
                        am335x_uart_txb(uart, '\r');
                am335x_uart_txb(uart, ch);
        }
}

static outdev_operations_t am335x_uart_ops = {
        .redraw = NULL,
        .write = am335x_uart_putchar,
};

static irq_ownership_t am335x_uart_claim(irq_t *irq)
{
        return IRQ_ACCEPT;
}

static void am335x_uart_handler(irq_t *irq)
{
        am335x_uart_t *uart = irq->instance;
        while ((uart->regs->rx_fifo_lvl)) {
                const uint8_t val = uart->regs->rhr;
                if (uart->indev && val) {
                        indev_push_character(uart->indev, val);
                }
        }
}

bool am335x_uart_init(
    am335x_uart_t *uart, inr_t interrupt, uintptr_t addr, size_t size)
{
        ASSERT(uart);
        uart->regs = (void *)km_map(addr, size, PAGE_NOT_CACHEABLE);

        ASSERT(uart->regs);

        /* Soft reset the port */
        uart->regs->sysc = AM335x_UART_SYSC_SOFTRESET_FLAG;
        while (!(uart->regs->syss & AM335x_UART_SYSS_RESETDONE_FLAG)) ;

        /* Enable access to EFR register */
        const uint8_t lcr = uart->regs->lcr; /* Save old value */
        uart->regs->lcr = 0xbf;              /* Sets config mode B */

        /* Enable access to TCL_TLR register */
        const bool enhanced = uart->regs->efr & AM335x_UART_EFR_ENH_FLAG;
        uart->regs->efr |= AM335x_UART_EFR_ENH_FLAG; /* Turn on enh. */
        uart->regs->lcr = 0x80;              /* Config mode A */

        /* Set default (val 0) triggers, disable DMA enable FIFOs */
        const bool tcl_tlr = uart->regs->mcr & AM335x_UART_MCR_TCR_TLR_FLAG;
        /* Enable access to tcr and tlr registers */
        uart->regs->mcr |= AM335x_UART_MCR_TCR_TLR_FLAG;

        /* Enable FIFOs */
        uart->regs->fcr = AM335x_UART_FCR_FIFO_EN_FLAG;

        /* Enable fine granularity for RX FIFO and set trigger level to 1,
         * TX FIFO, trigger level is irrilevant*/
        uart->regs->lcr = 0xbf;              /* Sets config mode B */
        uart->regs->scr = AM335x_UART_SCR_RX_TRIG_GRANU1_FLAG;
        uart->regs->tlr = 1 << AM335x_UART_TLR_RX_FIFO_TRIG_SHIFT;

        /* Restore enhanced */
        if (!enhanced)
                uart->regs->efr &= ~AM335x_UART_EFR_ENH_FLAG;

        uart->regs->lcr = 0x80;              /* Config mode A */
        /* Restore tcl_lcr access flag*/
        if (!tcl_tlr)
                uart->regs->mcr &= ~AM335x_UART_MCR_TCR_TLR_FLAG;

        /* Restore lcr */
        uart->regs->lcr = lcr;

        /* Disable interrupts */
        uart->regs->ier = 0;

        /* Setup outdev */
        outdev_initialize("am335x_uart_dev", &uart->outdev, &am335x_uart_ops);
        uart->outdev.data = uart;

        /* Initialize IRQ */
        irq_initialize(&uart->irq);
        uart->irq.devno = device_assign_devno();
        uart->irq.inr = interrupt;
        uart->irq.claim = am335x_uart_claim;
        uart->irq.handler = am335x_uart_handler;
        uart->irq.instance = uart;

        return true;
}

void am335x_uart_input_wire(am335x_uart_t *uart, indev_t *indev)
{
        ASSERT(uart);
        /* Set indev */
        uart->indev = indev;
        /* Register interrupt. */
        irq_register(&uart->irq);
        /* Enable interrupt on receive */
        uart->regs->ier |= AM335x_UART_IER_RHR_IRQ_FLAG;
}

/**
 * @}
 */