apbuart.c

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/*
 *  Driver for GRLIB serial ports (APBUART)
 *
 *  Based on linux/drivers/serial/amba.c
 *
 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
 *  Copyright (C) 2003 Konrad Eisele <[email protected]>
 *  Copyright (C) 2006 Daniel Hellstrom <[email protected]>, Aeroflex Gaisler AB
 *  Copyright (C) 2008 Gilead Kutnick <[email protected]>
 *  Copyright (C) 2009 Kristoffer Glembo <[email protected]>, Aeroflex Gaisler AB
 */

#if defined(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/kthread.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/serial_core.h>
#include <asm/irq.h>

#include "apbuart.h"

#define SERIAL_APBUART_MAJOR    TTY_MAJOR
#define SERIAL_APBUART_MINOR    64
#define UART_DUMMY_RSR_RX   0x8000  /* for ignore all read */

static void apbuart_tx_chars(struct uart_port *port);

static void apbuart_stop_tx(struct uart_port *port)
{
    unsigned int cr;

    cr = UART_GET_CTRL(port);
    cr &= ~UART_CTRL_TI;
    UART_PUT_CTRL(port, cr);
}

static void apbuart_start_tx(struct uart_port *port)
{
    unsigned int cr;

    cr = UART_GET_CTRL(port);
    cr |= UART_CTRL_TI;
    UART_PUT_CTRL(port, cr);

    if (UART_GET_STATUS(port) & UART_STATUS_THE)
        apbuart_tx_chars(port);
}

static void apbuart_stop_rx(struct uart_port *port)
{
    unsigned int cr;

    cr = UART_GET_CTRL(port);
    cr &= ~(UART_CTRL_RI);
    UART_PUT_CTRL(port, cr);
}

static void apbuart_enable_ms(struct uart_port *port)
{
    /* No modem status change interrupts for APBUART */
}

static void apbuart_rx_chars(struct uart_port *port)
{
    struct tty_struct *tty = port->state->port.tty;
    unsigned int status, ch, rsr, flag;
    unsigned int max_chars = port->fifosize;

    status = UART_GET_STATUS(port);

    while (UART_RX_DATA(status) && (max_chars--)) {

        ch = UART_GET_CHAR(port);
        flag = TTY_NORMAL;

        port->icount.rx++;

        rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
        UART_PUT_STATUS(port, 0);
        if (rsr & UART_STATUS_ERR) {

            if (rsr & UART_STATUS_BR) {
                rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
                port->icount.brk++;
                if (uart_handle_break(port))
                    goto ignore_char;
            } else if (rsr & UART_STATUS_PE) {
                port->icount.parity++;
            } else if (rsr & UART_STATUS_FE) {
                port->icount.frame++;
            }
            if (rsr & UART_STATUS_OE)
                port->icount.overrun++;

            rsr &= port->read_status_mask;

            if (rsr & UART_STATUS_PE)
                flag = TTY_PARITY;
            else if (rsr & UART_STATUS_FE)
                flag = TTY_FRAME;
        }

        if (uart_handle_sysrq_char(port, ch))
            goto ignore_char;

        uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);


          ignore_char:
        status = UART_GET_STATUS(port);
    }

    tty_flip_buffer_push(tty);
}

static void apbuart_tx_chars(struct uart_port *port)
{
    struct circ_buf *xmit = &port->state->xmit;
    int count;

    if (port->x_char) {
        UART_PUT_CHAR(port, port->x_char);
        port->icount.tx++;
        port->x_char = 0;
        return;
    }

    if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
        apbuart_stop_tx(port);
        return;
    }

    /* amba: fill FIFO */
    count = port->fifosize >> 1;
    do {
        UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
        xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
        port->icount.tx++;
        if (uart_circ_empty(xmit))
            break;
    } while (--count > 0);

    if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
        uart_write_wakeup(port);

    if (uart_circ_empty(xmit))
        apbuart_stop_tx(port);
}

static irqreturn_t apbuart_int(int irq, void *dev_id)
{
    struct uart_port *port = dev_id;
    unsigned int status;

    spin_lock(&port->lock);

    status = UART_GET_STATUS(port);
    if (status & UART_STATUS_DR)
        apbuart_rx_chars(port);
    if (status & UART_STATUS_THE)
        apbuart_tx_chars(port);

    spin_unlock(&port->lock);

    return IRQ_HANDLED;
}

static unsigned int apbuart_tx_empty(struct uart_port *port)
{
    unsigned int status = UART_GET_STATUS(port);
    return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
}

static unsigned int apbuart_get_mctrl(struct uart_port *port)
{
    /* The GRLIB APBUART handles flow control in hardware */
    return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
}

static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
    /* The GRLIB APBUART handles flow control in hardware */
}

static void apbuart_break_ctl(struct uart_port *port, int break_state)
{
    /* We don't support sending break */
}

static int apbuart_startup(struct uart_port *port)
{
    int retval;
    unsigned int cr;

    /* Allocate the IRQ */
    retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
    if (retval)
        return retval;

    /* Finally, enable interrupts */
    cr = UART_GET_CTRL(port);
    UART_PUT_CTRL(port,
              cr | UART_CTRL_RE | UART_CTRL_TE |
              UART_CTRL_RI | UART_CTRL_TI);

    return 0;
}

static void apbuart_shutdown(struct uart_port *port)
{
    unsigned int cr;

    /* disable all interrupts, disable the port */
    cr = UART_GET_CTRL(port);
    UART_PUT_CTRL(port,
              cr & ~(UART_CTRL_RE | UART_CTRL_TE |
                 UART_CTRL_RI | UART_CTRL_TI));

    /* Free the interrupt */
    free_irq(port->irq, port);
}

static void apbuart_set_termios(struct uart_port *port,
                struct ktermios *termios, struct ktermios *old)
{
    unsigned int cr;
    unsigned long flags;
    unsigned int baud, quot;

    /* Ask the core to calculate the divisor for us. */
    baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
    if (baud == 0)
        panic("invalid baudrate %i\n", port->uartclk / 16);

    /* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
    quot = (uart_get_divisor(port, baud)) * 2;
    cr = UART_GET_CTRL(port);
    cr &= ~(UART_CTRL_PE | UART_CTRL_PS);

    if (termios->c_cflag & PARENB) {
        cr |= UART_CTRL_PE;
        if ((termios->c_cflag & PARODD))
            cr |= UART_CTRL_PS;
    }

    /* Enable flow control. */
    if (termios->c_cflag & CRTSCTS)
        cr |= UART_CTRL_FL;

    spin_lock_irqsave(&port->lock, flags);

    /* Update the per-port timeout. */
    uart_update_timeout(port, termios->c_cflag, baud);

    port->read_status_mask = UART_STATUS_OE;
    if (termios->c_iflag & INPCK)
        port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;

    /* Characters to ignore */
    port->ignore_status_mask = 0;
    if (termios->c_iflag & IGNPAR)
        port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;

    /* Ignore all characters if CREAD is not set. */
    if ((termios->c_cflag & CREAD) == 0)
        port->ignore_status_mask |= UART_DUMMY_RSR_RX;

    /* Set baud rate */
    quot -= 1;
    UART_PUT_SCAL(port, quot);
    UART_PUT_CTRL(port, cr);

    spin_unlock_irqrestore(&port->lock, flags);
}

static const char *apbuart_type(struct uart_port *port)
{
    return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
}

static void apbuart_release_port(struct uart_port *port)
{
    release_mem_region(port->mapbase, 0x100);
}

static int apbuart_request_port(struct uart_port *port)
{
    return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
        != NULL ? 0 : -EBUSY;
    return 0;
}

/* Configure/autoconfigure the port */
static void apbuart_config_port(struct uart_port *port, int flags)
{
    if (flags & UART_CONFIG_TYPE) {
        port->type = PORT_APBUART;
        apbuart_request_port(port);
    }
}

/* Verify the new serial_struct (for TIOCSSERIAL) */
static int apbuart_verify_port(struct uart_port *port,
                   struct serial_struct *ser)
{
    int ret = 0;
    if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
        ret = -EINVAL;
    if (ser->irq < 0 || ser->irq >= NR_IRQS)
        ret = -EINVAL;
    if (ser->baud_base < 9600)
        ret = -EINVAL;
    return ret;
}

static struct uart_ops grlib_apbuart_ops = {
    .tx_empty = apbuart_tx_empty,
    .set_mctrl = apbuart_set_mctrl,
    .get_mctrl = apbuart_get_mctrl,
    .stop_tx = apbuart_stop_tx,
    .start_tx = apbuart_start_tx,
    .stop_rx = apbuart_stop_rx,
    .enable_ms = apbuart_enable_ms,
    .break_ctl = apbuart_break_ctl,
    .startup = apbuart_startup,
    .shutdown = apbuart_shutdown,
    .set_termios = apbuart_set_termios,
    .type = apbuart_type,
    .release_port = apbuart_release_port,
    .request_port = apbuart_request_port,
    .config_port = apbuart_config_port,
    .verify_port = apbuart_verify_port,
};

static struct uart_port grlib_apbuart_ports[UART_NR];
static struct device_node *grlib_apbuart_nodes[UART_NR];

static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
{
    int ctrl, loop = 0;
    int status;
    int fifosize;
    unsigned long flags;

    ctrl = UART_GET_CTRL(port);

    /*
     * Enable the transceiver and wait for it to be ready to send data.
     * Clear interrupts so that this process will not be externally
     * interrupted in the middle (which can cause the transceiver to
     * drain prematurely).
     */

    local_irq_save(flags);

    UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);

    while (!UART_TX_READY(UART_GET_STATUS(port)))
        loop++;

    /*
     * Disable the transceiver so data isn't actually sent during the
     * actual test.
     */

    UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));

    fifosize = 1;
    UART_PUT_CHAR(port, 0);

    /*
     * So long as transmitting a character increments the tranceivier FIFO
     * length the FIFO must be at least that big. These bytes will
     * automatically drain off of the FIFO.
     */

    status = UART_GET_STATUS(port);
    while (((status >> 20) & 0x3F) == fifosize) {
        fifosize++;
        UART_PUT_CHAR(port, 0);
        status = UART_GET_STATUS(port);
    }

    fifosize--;

    UART_PUT_CTRL(port, ctrl);
    local_irq_restore(flags);

    if (fifosize == 0)
        fifosize = 1;

    return fifosize;
}

static void apbuart_flush_fifo(struct uart_port *port)
{
    int i;

    for (i = 0; i < port->fifosize; i++)
        UART_GET_CHAR(port);
}


/* ======================================================================== */
/* Console driver, if enabled                                               */
/* ======================================================================== */

#ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE

static void apbuart_console_putchar(struct uart_port *port, int ch)
{
    unsigned int status;
    do {
        status = UART_GET_STATUS(port);
    } while (!UART_TX_READY(status));
    UART_PUT_CHAR(port, ch);
}

static void
apbuart_console_write(struct console *co, const char *s, unsigned int count)
{
    struct uart_port *port = &grlib_apbuart_ports[co->index];
    unsigned int status, old_cr, new_cr;

    /* First save the CR then disable the interrupts */
    old_cr = UART_GET_CTRL(port);
    new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
    UART_PUT_CTRL(port, new_cr);

    uart_console_write(port, s, count, apbuart_console_putchar);

    /*
     *      Finally, wait for transmitter to become empty
     *      and restore the TCR
     */
    do {
        status = UART_GET_STATUS(port);
    } while (!UART_TX_READY(status));
    UART_PUT_CTRL(port, old_cr);
}

static void __init
apbuart_console_get_options(struct uart_port *port, int *baud,
                int *parity, int *bits)
{
    if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {

        unsigned int quot, status;
        status = UART_GET_STATUS(port);

        *parity = 'n';
        if (status & UART_CTRL_PE) {
            if ((status & UART_CTRL_PS) == 0)
                *parity = 'e';
            else
                *parity = 'o';
        }

        *bits = 8;
        quot = UART_GET_SCAL(port) / 8;
        *baud = port->uartclk / (16 * (quot + 1));
    }
}

static int __init apbuart_console_setup(struct console *co, char *options)
{
    struct uart_port *port;
    int baud = 38400;
    int bits = 8;
    int parity = 'n';
    int flow = 'n';

    pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
         co, co->index, options);

    /*
     * Check whether an invalid uart number has been specified, and
     * if so, search for the first available port that does have
     * console support.
     */
    if (co->index >= grlib_apbuart_port_nr)
        co->index = 0;

    port = &grlib_apbuart_ports[co->index];

    spin_lock_init(&port->lock);

    if (options)
        uart_parse_options(options, &baud, &parity, &bits, &flow);
    else
        apbuart_console_get_options(port, &baud, &parity, &bits);

    return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct uart_driver grlib_apbuart_driver;

static struct console grlib_apbuart_console = {
    .name = "ttyS",
    .write = apbuart_console_write,
    .device = uart_console_device,
    .setup = apbuart_console_setup,
    .flags = CON_PRINTBUFFER,
    .index = -1,
    .data = &grlib_apbuart_driver,
};


static int grlib_apbuart_configure(void);

static int __init apbuart_console_init(void)
{
    if (grlib_apbuart_configure())
        return -ENODEV;
    register_console(&grlib_apbuart_console);
    return 0;
}

console_initcall(apbuart_console_init);

#define APBUART_CONSOLE (&grlib_apbuart_console)
#else
#define APBUART_CONSOLE NULL
#endif

static struct uart_driver grlib_apbuart_driver = {
    .owner = THIS_MODULE,
    .driver_name = "serial",
    .dev_name = "ttyS",
    .major = SERIAL_APBUART_MAJOR,
    .minor = SERIAL_APBUART_MINOR,
    .nr = UART_NR,
    .cons = APBUART_CONSOLE,
};


/* ======================================================================== */
/* OF Platform Driver                                                       */
/* ======================================================================== */

static int __devinit apbuart_probe(struct platform_device *op)
{
    int i;
    struct uart_port *port = NULL;

    for (i = 0; i < grlib_apbuart_port_nr; i++) {
        if (op->dev.of_node == grlib_apbuart_nodes[i])
            break;
    }

    port = &grlib_apbuart_ports[i];
    port->dev = &op->dev;
    port->irq = op->archdata.irqs[0];

    uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);

    apbuart_flush_fifo((struct uart_port *) port);

    printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
           (unsigned long long) port->mapbase, port->irq);
    return 0;
}

static struct of_device_id apbuart_match[] = {
    {
     .name = "GAISLER_APBUART",
     },
    {
     .name = "01_00c",
     },
    {},
};

static struct platform_driver grlib_apbuart_of_driver = {
    .probe = apbuart_probe,
    .driver = {
        .owner = THIS_MODULE,
        .name = "grlib-apbuart",
        .of_match_table = apbuart_match,
    },
};


static int __init grlib_apbuart_configure(void)
{
    struct device_node *np;
    int line = 0;

    for_each_matching_node(np, apbuart_match) {
        const int *ampopts;
        const u32 *freq_hz;
        const struct amba_prom_registers *regs;
        struct uart_port *port;
        unsigned long addr;

        ampopts = of_get_property(np, "ampopts", NULL);
        if (ampopts && (*ampopts == 0))
            continue; /* Ignore if used by another OS instance */
        regs = of_get_property(np, "reg", NULL);
        /* Frequency of APB Bus is frequency of UART */
        freq_hz = of_get_property(np, "freq", NULL);

        if (!regs || !freq_hz || (*freq_hz == 0))
            continue;

        grlib_apbuart_nodes[line] = np;

        addr = regs->phys_addr;

        port = &grlib_apbuart_ports[line];

        port->mapbase = addr;
        port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
        port->irq = 0;
        port->iotype = UPIO_MEM;
        port->ops = &grlib_apbuart_ops;
        port->flags = UPF_BOOT_AUTOCONF;
        port->line = line;
        port->uartclk = *freq_hz;
        port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
        line++;

        /* We support maximum UART_NR uarts ... */
        if (line == UART_NR)
            break;
    }

    grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
    return line ? 0 : -ENODEV;
}

static int __init grlib_apbuart_init(void)
{
    int ret;

    /* Find all APBUARTS in device the tree and initialize their ports */
    ret = grlib_apbuart_configure();
    if (ret)
        return ret;

    printk(KERN_INFO "Serial: GRLIB APBUART driver\n");

    ret = uart_register_driver(&grlib_apbuart_driver);

    if (ret) {
        printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
               __FILE__, ret);
        return ret;
    }

    ret = platform_driver_register(&grlib_apbuart_of_driver);
    if (ret) {
        printk(KERN_ERR
               "%s: platform_driver_register failed (%i)\n",
               __FILE__, ret);
        uart_unregister_driver(&grlib_apbuart_driver);
        return ret;
    }

    return ret;
}

static void __exit grlib_apbuart_exit(void)
{
    int i;

    for (i = 0; i < grlib_apbuart_port_nr; i++)
        uart_remove_one_port(&grlib_apbuart_driver,
                     &grlib_apbuart_ports[i]);

    uart_unregister_driver(&grlib_apbuart_driver);
    platform_driver_unregister(&grlib_apbuart_of_driver);
}

module_init(grlib_apbuart_init);
module_exit(grlib_apbuart_exit);

MODULE_AUTHOR("Aeroflex Gaisler AB");
MODULE_DESCRIPTION("GRLIB APBUART serial driver");
MODULE_VERSION("2.1");
MODULE_LICENSE("GPL");