sunhv.c

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/* sunhv.c: Serial driver for SUN4V hypervisor console.
 *
 * Copyright (C) 2006, 2007 David S. Miller ([email protected])
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/circ_buf.h>
#include <linux/serial.h>
#include <linux/sysrq.h>
#include <linux/console.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/of_device.h>

#include <asm/hypervisor.h>
#include <asm/spitfire.h>
#include <asm/prom.h>
#include <asm/irq.h>
#include <asm/setup.h>

#if defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>
#include <linux/sunserialcore.h>

#define CON_BREAK   ((long)-1)
#define CON_HUP     ((long)-2)

#define IGNORE_BREAK    0x1
#define IGNORE_ALL  0x2

static char *con_write_page;
static char *con_read_page;

static int hung_up = 0;

static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
{
    while (!uart_circ_empty(xmit)) {
        long status = sun4v_con_putchar(xmit->buf[xmit->tail]);

        if (status != HV_EOK)
            break;

        xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
        port->icount.tx++;
    }
}

static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
{
    while (!uart_circ_empty(xmit)) {
        unsigned long ra = __pa(xmit->buf + xmit->tail);
        unsigned long len, status, sent;

        len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
                      UART_XMIT_SIZE);
        status = sun4v_con_write(ra, len, &sent);
        if (status != HV_EOK)
            break;
        xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
        port->icount.tx += sent;
    }
}

static int receive_chars_getchar(struct uart_port *port, struct tty_struct *tty)
{
    int saw_console_brk = 0;
    int limit = 10000;

    while (limit-- > 0) {
        long status;
        long c = sun4v_con_getchar(&status);

        if (status == HV_EWOULDBLOCK)
            break;

        if (c == CON_BREAK) {
            if (uart_handle_break(port))
                continue;
            saw_console_brk = 1;
            c = 0;
        }

        if (c == CON_HUP) {
            hung_up = 1;
            uart_handle_dcd_change(port, 0);
        } else if (hung_up) {
            hung_up = 0;
            uart_handle_dcd_change(port, 1);
        }

        if (tty == NULL) {
            uart_handle_sysrq_char(port, c);
            continue;
        }

        port->icount.rx++;

        if (uart_handle_sysrq_char(port, c))
            continue;

        tty_insert_flip_char(tty, c, TTY_NORMAL);
    }

    return saw_console_brk;
}

static int receive_chars_read(struct uart_port *port, struct tty_struct *tty)
{
    int saw_console_brk = 0;
    int limit = 10000;

    while (limit-- > 0) {
        unsigned long ra = __pa(con_read_page);
        unsigned long bytes_read, i;
        long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);

        if (stat != HV_EOK) {
            bytes_read = 0;

            if (stat == CON_BREAK) {
                if (uart_handle_break(port))
                    continue;
                saw_console_brk = 1;
                *con_read_page = 0;
                bytes_read = 1;
            } else if (stat == CON_HUP) {
                hung_up = 1;
                uart_handle_dcd_change(port, 0);
                continue;
            } else {
                /* HV_EWOULDBLOCK, etc.  */
                break;
            }
        }

        if (hung_up) {
            hung_up = 0;
            uart_handle_dcd_change(port, 1);
        }

        for (i = 0; i < bytes_read; i++)
            uart_handle_sysrq_char(port, con_read_page[i]);

        if (tty == NULL)
            continue;

        port->icount.rx += bytes_read;

        tty_insert_flip_string(tty, con_read_page, bytes_read);
    }

    return saw_console_brk;
}

struct sunhv_ops {
    void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
    int (*receive_chars)(struct uart_port *port, struct tty_struct *tty);
};

static struct sunhv_ops bychar_ops = {
    .transmit_chars = transmit_chars_putchar,
    .receive_chars = receive_chars_getchar,
};

static struct sunhv_ops bywrite_ops = {
    .transmit_chars = transmit_chars_write,
    .receive_chars = receive_chars_read,
};

static struct sunhv_ops *sunhv_ops = &bychar_ops;

static struct tty_struct *receive_chars(struct uart_port *port)
{
    struct tty_struct *tty = NULL;

    if (port->state != NULL)        /* Unopened serial console */
        tty = port->state->port.tty;

    if (sunhv_ops->receive_chars(port, tty))
        sun_do_break();

    return tty;
}

static void transmit_chars(struct uart_port *port)
{
    struct circ_buf *xmit;

    if (!port->state)
        return;

    xmit = &port->state->xmit;
    if (uart_circ_empty(xmit) || uart_tx_stopped(port))
        return;

    sunhv_ops->transmit_chars(port, xmit);

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

static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
{
    struct uart_port *port = dev_id;
    struct tty_struct *tty;
    unsigned long flags;

    spin_lock_irqsave(&port->lock, flags);
    tty = receive_chars(port);
    transmit_chars(port);
    spin_unlock_irqrestore(&port->lock, flags);

    if (tty)
        tty_flip_buffer_push(tty);

    return IRQ_HANDLED;
}

/* port->lock is not held.  */
static unsigned int sunhv_tx_empty(struct uart_port *port)
{
    /* Transmitter is always empty for us.  If the circ buffer
     * is non-empty or there is an x_char pending, our caller
     * will do the right thing and ignore what we return here.
     */
    return TIOCSER_TEMT;
}

/* port->lock held by caller.  */
static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
    return;
}

/* port->lock is held by caller and interrupts are disabled.  */
static unsigned int sunhv_get_mctrl(struct uart_port *port)
{
    return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
}

/* port->lock held by caller.  */
static void sunhv_stop_tx(struct uart_port *port)
{
    return;
}

/* port->lock held by caller.  */
static void sunhv_start_tx(struct uart_port *port)
{
    transmit_chars(port);
}

/* port->lock is not held.  */
static void sunhv_send_xchar(struct uart_port *port, char ch)
{
    unsigned long flags;
    int limit = 10000;

    spin_lock_irqsave(&port->lock, flags);

    while (limit-- > 0) {
        long status = sun4v_con_putchar(ch);
        if (status == HV_EOK)
            break;
        udelay(1);
    }

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

/* port->lock held by caller.  */
static void sunhv_stop_rx(struct uart_port *port)
{
}

/* port->lock held by caller.  */
static void sunhv_enable_ms(struct uart_port *port)
{
}

/* port->lock is not held.  */
static void sunhv_break_ctl(struct uart_port *port, int break_state)
{
    if (break_state) {
        unsigned long flags;
        int limit = 10000;

        spin_lock_irqsave(&port->lock, flags);

        while (limit-- > 0) {
            long status = sun4v_con_putchar(CON_BREAK);
            if (status == HV_EOK)
                break;
            udelay(1);
        }

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

/* port->lock is not held.  */
static int sunhv_startup(struct uart_port *port)
{
    return 0;
}

/* port->lock is not held.  */
static void sunhv_shutdown(struct uart_port *port)
{
}

/* port->lock is not held.  */
static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
                  struct ktermios *old)
{
    unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
    unsigned int quot = uart_get_divisor(port, baud);
    unsigned int iflag, cflag;
    unsigned long flags;

    spin_lock_irqsave(&port->lock, flags);

    iflag = termios->c_iflag;
    cflag = termios->c_cflag;

    port->ignore_status_mask = 0;
    if (iflag & IGNBRK)
        port->ignore_status_mask |= IGNORE_BREAK;
    if ((cflag & CREAD) == 0)
        port->ignore_status_mask |= IGNORE_ALL;

    /* XXX */
    uart_update_timeout(port, cflag,
                (port->uartclk / (16 * quot)));

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

static const char *sunhv_type(struct uart_port *port)
{
    return "SUN4V HCONS";
}

static void sunhv_release_port(struct uart_port *port)
{
}

static int sunhv_request_port(struct uart_port *port)
{
    return 0;
}

static void sunhv_config_port(struct uart_port *port, int flags)
{
}

static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
{
    return -EINVAL;
}

static struct uart_ops sunhv_pops = {
    .tx_empty   = sunhv_tx_empty,
    .set_mctrl  = sunhv_set_mctrl,
    .get_mctrl  = sunhv_get_mctrl,
    .stop_tx    = sunhv_stop_tx,
    .start_tx   = sunhv_start_tx,
    .send_xchar = sunhv_send_xchar,
    .stop_rx    = sunhv_stop_rx,
    .enable_ms  = sunhv_enable_ms,
    .break_ctl  = sunhv_break_ctl,
    .startup    = sunhv_startup,
    .shutdown   = sunhv_shutdown,
    .set_termios    = sunhv_set_termios,
    .type       = sunhv_type,
    .release_port   = sunhv_release_port,
    .request_port   = sunhv_request_port,
    .config_port    = sunhv_config_port,
    .verify_port    = sunhv_verify_port,
};

static struct uart_driver sunhv_reg = {
    .owner          = THIS_MODULE,
    .driver_name        = "sunhv",
    .dev_name       = "ttyS",
    .major          = TTY_MAJOR,
};

static struct uart_port *sunhv_port;

/* Copy 's' into the con_write_page, decoding "\n" into
 * "\r\n" along the way.  We have to return two lengths
 * because the caller needs to know how much to advance
 * 's' and also how many bytes to output via con_write_page.
 */
static int fill_con_write_page(const char *s, unsigned int n,
                   unsigned long *page_bytes)
{
    const char *orig_s = s;
    char *p = con_write_page;
    int left = PAGE_SIZE;

    while (n--) {
        if (*s == '\n') {
            if (left < 2)
                break;
            *p++ = '\r';
            left--;
        } else if (left < 1)
            break;
        *p++ = *s++;
        left--;
    }
    *page_bytes = p - con_write_page;
    return s - orig_s;
}

static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
{
    struct uart_port *port = sunhv_port;
    unsigned long flags;
    int locked = 1;

    local_irq_save(flags);
    if (port->sysrq) {
        locked = 0;
    } else if (oops_in_progress) {
        locked = spin_trylock(&port->lock);
    } else
        spin_lock(&port->lock);

    while (n > 0) {
        unsigned long ra = __pa(con_write_page);
        unsigned long page_bytes;
        unsigned int cpy = fill_con_write_page(s, n,
                               &page_bytes);

        n -= cpy;
        s += cpy;
        while (page_bytes > 0) {
            unsigned long written;
            int limit = 1000000;

            while (limit--) {
                unsigned long stat;

                stat = sun4v_con_write(ra, page_bytes,
                               &written);
                if (stat == HV_EOK)
                    break;
                udelay(1);
            }
            if (limit < 0)
                break;
            page_bytes -= written;
            ra += written;
        }
    }

    if (locked)
        spin_unlock(&port->lock);
    local_irq_restore(flags);
}

static inline void sunhv_console_putchar(struct uart_port *port, char c)
{
    int limit = 1000000;

    while (limit-- > 0) {
        long status = sun4v_con_putchar(c);
        if (status == HV_EOK)
            break;
        udelay(1);
    }
}

static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
{
    struct uart_port *port = sunhv_port;
    unsigned long flags;
    int i, locked = 1;

    local_irq_save(flags);
    if (port->sysrq) {
        locked = 0;
    } else if (oops_in_progress) {
        locked = spin_trylock(&port->lock);
    } else
        spin_lock(&port->lock);

    for (i = 0; i < n; i++) {
        if (*s == '\n')
            sunhv_console_putchar(port, '\r');
        sunhv_console_putchar(port, *s++);
    }

    if (locked)
        spin_unlock(&port->lock);
    local_irq_restore(flags);
}

static struct console sunhv_console = {
    .name   =   "ttyHV",
    .write  =   sunhv_console_write_bychar,
    .device =   uart_console_device,
    .flags  =   CON_PRINTBUFFER,
    .index  =   -1,
    .data   =   &sunhv_reg,
};

static int __devinit hv_probe(struct platform_device *op)
{
    struct uart_port *port;
    unsigned long minor;
    int err;

    if (op->archdata.irqs[0] == 0xffffffff)
        return -ENODEV;

    port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
    if (unlikely(!port))
        return -ENOMEM;

    minor = 1;
    if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
        minor >= 1) {
        err = -ENOMEM;
        con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
        if (!con_write_page)
            goto out_free_port;

        con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
        if (!con_read_page)
            goto out_free_con_write_page;

        sunhv_console.write = sunhv_console_write_paged;
        sunhv_ops = &bywrite_ops;
    }

    sunhv_port = port;

    port->line = 0;
    port->ops = &sunhv_pops;
    port->type = PORT_SUNHV;
    port->uartclk = ( 29491200 / 16 ); /* arbitrary */

    port->membase = (unsigned char __iomem *) __pa(port);

    port->irq = op->archdata.irqs[0];

    port->dev = &op->dev;

    err = sunserial_register_minors(&sunhv_reg, 1);
    if (err)
        goto out_free_con_read_page;

    sunserial_console_match(&sunhv_console, op->dev.of_node,
                &sunhv_reg, port->line, false);

    err = uart_add_one_port(&sunhv_reg, port);
    if (err)
        goto out_unregister_driver;

    err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
    if (err)
        goto out_remove_port;

    dev_set_drvdata(&op->dev, port);

    return 0;

out_remove_port:
    uart_remove_one_port(&sunhv_reg, port);

out_unregister_driver:
    sunserial_unregister_minors(&sunhv_reg, 1);

out_free_con_read_page:
    kfree(con_read_page);

out_free_con_write_page:
    kfree(con_write_page);

out_free_port:
    kfree(port);
    sunhv_port = NULL;
    return err;
}

static int __devexit hv_remove(struct platform_device *dev)
{
    struct uart_port *port = dev_get_drvdata(&dev->dev);

    free_irq(port->irq, port);

    uart_remove_one_port(&sunhv_reg, port);

    sunserial_unregister_minors(&sunhv_reg, 1);

    kfree(port);
    sunhv_port = NULL;

    dev_set_drvdata(&dev->dev, NULL);

    return 0;
}

static const struct of_device_id hv_match[] = {
    {
        .name = "console",
        .compatible = "qcn",
    },
    {
        .name = "console",
        .compatible = "SUNW,sun4v-console",
    },
    {},
};
MODULE_DEVICE_TABLE(of, hv_match);

static struct platform_driver hv_driver = {
    .driver = {
        .name = "hv",
        .owner = THIS_MODULE,
        .of_match_table = hv_match,
    },
    .probe      = hv_probe,
    .remove     = __devexit_p(hv_remove),
};

static int __init sunhv_init(void)
{
    if (tlb_type != hypervisor)
        return -ENODEV;

    return platform_driver_register(&hv_driver);
}

static void __exit sunhv_exit(void)
{
    platform_driver_unregister(&hv_driver);
}

module_init(sunhv_init);
module_exit(sunhv_exit);

MODULE_AUTHOR("David S. Miller");
MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
MODULE_VERSION("2.0");
MODULE_LICENSE("GPL");