sn_console.c

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/*
 * C-Brick Serial Port (and console) driver for SGI Altix machines.
 *
 * This driver is NOT suitable for talking to the l1-controller for
 * anything other than 'console activities' --- please use the l1
 * driver for that.
 *
 *
 * Copyright (c) 2004-2006 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/NoticeExplan
 */

#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/module.h>
#include <linux/sysrq.h>
#include <linux/circ_buf.h>
#include <linux/serial_reg.h>
#include <linux/delay.h> /* for mdelay */
#include <linux/miscdevice.h>
#include <linux/serial_core.h>

#include <asm/io.h>
#include <asm/sn/simulator.h>
#include <asm/sn/sn_sal.h>

/* number of characters we can transmit to the SAL console at a time */
#define SN_SAL_MAX_CHARS 120

/* 64K, when we're asynch, it must be at least printk's LOG_BUF_LEN to
 * avoid losing chars, (always has to be a power of 2) */
#define SN_SAL_BUFFER_SIZE (64 * (1 << 10))

#define SN_SAL_UART_FIFO_DEPTH 16
#define SN_SAL_UART_FIFO_SPEED_CPS 9600/10

/* sn_transmit_chars() calling args */
#define TRANSMIT_BUFFERED	0
#define TRANSMIT_RAW		1

/* To use dynamic numbers only and not use the assigned major and minor,
 * define the following.. */
				  /* #define USE_DYNAMIC_MINOR 1 *//* use dynamic minor number */
#define USE_DYNAMIC_MINOR 0	/* Don't rely on misc_register dynamic minor */

/* Device name we're using */
#define DEVICE_NAME "ttySG"
#define DEVICE_NAME_DYNAMIC "ttySG0"	/* need full name for misc_register */
/* The major/minor we are using, ignored for USE_DYNAMIC_MINOR */
#define DEVICE_MAJOR 204
#define DEVICE_MINOR 40

#ifdef CONFIG_MAGIC_SYSRQ
static char sysrq_serial_str[] = "\eSYS";
static char *sysrq_serial_ptr = sysrq_serial_str;
static unsigned long sysrq_requested;
#endif /* CONFIG_MAGIC_SYSRQ */

/*
 * Port definition - this kinda drives it all
 */
struct sn_cons_port {
	struct timer_list sc_timer;
	struct uart_port sc_port;
	struct sn_sal_ops {
		int (*sal_puts_raw) (const char *s, int len);
		int (*sal_puts) (const char *s, int len);
		int (*sal_getc) (void);
		int (*sal_input_pending) (void);
		void (*sal_wakeup_transmit) (struct sn_cons_port *, int);
	} *sc_ops;
	unsigned long sc_interrupt_timeout;
	int sc_is_asynch;
};

static struct sn_cons_port sal_console_port;
static int sn_process_input;

/* Only used if USE_DYNAMIC_MINOR is set to 1 */
static struct miscdevice misc;	/* used with misc_register for dynamic */

extern void early_sn_setup(void);

#undef DEBUG
#ifdef DEBUG
static int sn_debug_printf(const char *fmt, ...);
#define DPRINTF(x...) sn_debug_printf(x)
#else
#define DPRINTF(x...) do { } while (0)
#endif

/* Prototypes */
static int snt_hw_puts_raw(const char *, int);
static int snt_hw_puts_buffered(const char *, int);
static int snt_poll_getc(void);
static int snt_poll_input_pending(void);
static int snt_intr_getc(void);
static int snt_intr_input_pending(void);
static void sn_transmit_chars(struct sn_cons_port *, int);

/* A table for polling:
 */
static struct sn_sal_ops poll_ops = {
	.sal_puts_raw = snt_hw_puts_raw,
	.sal_puts = snt_hw_puts_raw,
	.sal_getc = snt_poll_getc,
	.sal_input_pending = snt_poll_input_pending
};

/* A table for interrupts enabled */
static struct sn_sal_ops intr_ops = {
	.sal_puts_raw = snt_hw_puts_raw,
	.sal_puts = snt_hw_puts_buffered,
	.sal_getc = snt_intr_getc,
	.sal_input_pending = snt_intr_input_pending,
	.sal_wakeup_transmit = sn_transmit_chars
};

/* the console does output in two distinctly different ways:
 * synchronous (raw) and asynchronous (buffered).  initally, early_printk
 * does synchronous output.  any data written goes directly to the SAL
 * to be output (incidentally, it is internally buffered by the SAL)
 * after interrupts and timers are initialized and available for use,
 * the console init code switches to asynchronous output.  this is
 * also the earliest opportunity to begin polling for console input.
 * after console initialization, console output and tty (serial port)
 * output is buffered and sent to the SAL asynchronously (either by
 * timer callback or by UART interrupt) */

/* routines for running the console in polling mode */

/**
 * snt_poll_getc - Get a character from the console in polling mode
 *
 */
static int snt_poll_getc(void)
{
	int ch;

	ia64_sn_console_getc(&ch);
	return ch;
}

/**
 * snt_poll_input_pending - Check if any input is waiting - polling mode.
 *
 */
static int snt_poll_input_pending(void)
{
	int status, input;

	status = ia64_sn_console_check(&input);
	return !status && input;
}

/* routines for an interrupt driven console (normal) */

/**
 * snt_intr_getc - Get a character from the console, interrupt mode
 *
 */
static int snt_intr_getc(void)
{
	return ia64_sn_console_readc();
}

/**
 * snt_intr_input_pending - Check if input is pending, interrupt mode
 *
 */
static int snt_intr_input_pending(void)
{
	return ia64_sn_console_intr_status() & SAL_CONSOLE_INTR_RECV;
}

/* these functions are polled and interrupt */

/**
 * snt_hw_puts_raw - Send raw string to the console, polled or interrupt mode
 * @s: String
 * @len: Length
 *
 */
static int snt_hw_puts_raw(const char *s, int len)
{
	/* this will call the PROM and not return until this is done */
	return ia64_sn_console_putb(s, len);
}

/**
 * snt_hw_puts_buffered - Send string to console, polled or interrupt mode
 * @s: String
 * @len: Length
 *
 */
static int snt_hw_puts_buffered(const char *s, int len)
{
	/* queue data to the PROM */
	return ia64_sn_console_xmit_chars((char *)s, len);
}

/* uart interface structs
 * These functions are associated with the uart_port that the serial core
 * infrastructure calls.
 *
 * Note: Due to how the console works, many routines are no-ops.
 */

/**
 * snp_type - What type of console are we?
 * @port: Port to operate with (we ignore since we only have one port)
 *
 */
static const char *snp_type(struct uart_port *port)
{
	return ("SGI SN L1");
}

/**
 * snp_tx_empty - Is the transmitter empty?  We pretend we're always empty
 * @port: Port to operate on (we ignore since we only have one port)
 *
 */
static unsigned int snp_tx_empty(struct uart_port *port)
{
	return 1;
}

/**
 * snp_stop_tx - stop the transmitter - no-op for us
 * @port: Port to operat eon - we ignore - no-op function
 *
 */
static void snp_stop_tx(struct uart_port *port)
{
}

/**
 * snp_release_port - Free i/o and resources for port - no-op for us
 * @port: Port to operate on - we ignore - no-op function
 *
 */
static void snp_release_port(struct uart_port *port)
{
}

/**
 * snp_enable_ms - Force modem status interrupts on - no-op for us
 * @port: Port to operate on - we ignore - no-op function
 *
 */
static void snp_enable_ms(struct uart_port *port)
{
}

/**
 * snp_shutdown - shut down the port - free irq and disable - no-op for us
 * @port: Port to shut down - we ignore
 *
 */
static void snp_shutdown(struct uart_port *port)
{
}

/**
 * snp_set_mctrl - set control lines (dtr, rts, etc) - no-op for our console
 * @port: Port to operate on - we ignore
 * @mctrl: Lines to set/unset - we ignore
 *
 */
static void snp_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

/**
 * snp_get_mctrl - get contorl line info, we just return a static value
 * @port: port to operate on - we only have one port so we ignore this
 *
 */
static unsigned int snp_get_mctrl(struct uart_port *port)
{
	return TIOCM_CAR | TIOCM_RNG | TIOCM_DSR | TIOCM_CTS;
}

/**
 * snp_stop_rx - Stop the receiver - we ignor ethis
 * @port: Port to operate on - we ignore
 *
 */
static void snp_stop_rx(struct uart_port *port)
{
}

/**
 * snp_start_tx - Start transmitter
 * @port: Port to operate on
 *
 */
static void snp_start_tx(struct uart_port *port)
{
	if (sal_console_port.sc_ops->sal_wakeup_transmit)
		sal_console_port.sc_ops->sal_wakeup_transmit(&sal_console_port,
							     TRANSMIT_BUFFERED);

}

/**
 * snp_break_ctl - handle breaks - ignored by us
 * @port: Port to operate on
 * @break_state: Break state
 *
 */
static void snp_break_ctl(struct uart_port *port, int break_state)
{
}

/**
 * snp_startup - Start up the serial port - always return 0 (We're always on)
 * @port: Port to operate on
 *
 */
static int snp_startup(struct uart_port *port)
{
	return 0;
}

/**
 * snp_set_termios - set termios stuff - we ignore these
 * @port: port to operate on
 * @termios: New settings
 * @termios: Old
 *
 */
static void
snp_set_termios(struct uart_port *port, struct ktermios *termios,
		struct ktermios *old)
{
}

/**
 * snp_request_port - allocate resources for port - ignored by us
 * @port: port to operate on
 *
 */
static int snp_request_port(struct uart_port *port)
{
	return 0;
}

/**
 * snp_config_port - allocate resources, set up - we ignore,  we're always on
 * @port: Port to operate on
 * @flags: flags used for port setup
 *
 */
static void snp_config_port(struct uart_port *port, int flags)
{
}

/* Associate the uart functions above - given to serial core */

static struct uart_ops sn_console_ops = {
	.tx_empty = snp_tx_empty,
	.set_mctrl = snp_set_mctrl,
	.get_mctrl = snp_get_mctrl,
	.stop_tx = snp_stop_tx,
	.start_tx = snp_start_tx,
	.stop_rx = snp_stop_rx,
	.enable_ms = snp_enable_ms,
	.break_ctl = snp_break_ctl,
	.startup = snp_startup,
	.shutdown = snp_shutdown,
	.set_termios = snp_set_termios,
	.pm = NULL,
	.type = snp_type,
	.release_port = snp_release_port,
	.request_port = snp_request_port,
	.config_port = snp_config_port,
	.verify_port = NULL,
};

/* End of uart struct functions and defines */

#ifdef DEBUG

/**
 * sn_debug_printf - close to hardware debugging printf
 * @fmt: printf format
 *
 * This is as "close to the metal" as we can get, used when the driver
 * itself may be broken.
 *
 */
static int sn_debug_printf(const char *fmt, ...)
{
	static char printk_buf[1024];
	int printed_len;
	va_list args;

	va_start(args, fmt);
	printed_len = vsnprintf(printk_buf, sizeof(printk_buf), fmt, args);

	if (!sal_console_port.sc_ops) {
		sal_console_port.sc_ops = &poll_ops;
		early_sn_setup();
	}
	sal_console_port.sc_ops->sal_puts_raw(printk_buf, printed_len);

	va_end(args);
	return printed_len;
}
#endif				/* DEBUG */

/*
 * Interrupt handling routines.
 */

/**
 * sn_receive_chars - Grab characters, pass them to tty layer
 * @port: Port to operate on
 * @flags: irq flags
 *
 * Note: If we're not registered with the serial core infrastructure yet,
 * we don't try to send characters to it...
 *
 */
static void
sn_receive_chars(struct sn_cons_port *port, unsigned long flags)
{
	int ch;
	struct tty_struct *tty;

	if (!port) {
		printk(KERN_ERR "sn_receive_chars - port NULL so can't receieve\n");
		return;
	}

	if (!port->sc_ops) {
		printk(KERN_ERR "sn_receive_chars - port->sc_ops  NULL so can't receieve\n");
		return;
	}

	if (port->sc_port.info) {
		/* The serial_core stuffs are initilized, use them */
		tty = port->sc_port.info->tty;
	}
	else {
		/* Not registered yet - can't pass to tty layer.  */
		tty = NULL;
	}

	while (port->sc_ops->sal_input_pending()) {
		ch = port->sc_ops->sal_getc();
		if (ch < 0) {
			printk(KERN_ERR "sn_console: An error occured while "
			       "obtaining data from the console (0x%0x)\n", ch);
			break;
		}
#ifdef CONFIG_MAGIC_SYSRQ
                if (sysrq_requested) {
                        unsigned long sysrq_timeout = sysrq_requested + HZ*5;

                        sysrq_requested = 0;
                        if (ch && time_before(jiffies, sysrq_timeout)) {
                                spin_unlock_irqrestore(&port->sc_port.lock, flags);
                                handle_sysrq(ch, NULL);
                                spin_lock_irqsave(&port->sc_port.lock, flags);
                                /* ignore actual sysrq command char */
                                continue;
                        }
                }
                if (ch == *sysrq_serial_ptr) {
                        if (!(*++sysrq_serial_ptr)) {
                                sysrq_requested = jiffies;
                                sysrq_serial_ptr = sysrq_serial_str;
                        }
			/*
			 * ignore the whole sysrq string except for the
			 * leading escape
			 */
			if (ch != '\e')
				continue;
                }
                else
			sysrq_serial_ptr = sysrq_serial_str;
#endif /* CONFIG_MAGIC_SYSRQ */

		/* record the character to pass up to the tty layer */
		if (tty) {
			if(tty_insert_flip_char(tty, ch, TTY_NORMAL) == 0)
				break;
		}
		port->sc_port.icount.rx++;
	}

	if (tty)
		tty_flip_buffer_push(tty);
}

/**
 * sn_transmit_chars - grab characters from serial core, send off
 * @port: Port to operate on
 * @raw: Transmit raw or buffered
 *
 * Note: If we're early, before we're registered with serial core, the
 * writes are going through sn_sal_console_write because that's how
 * register_console has been set up.  We currently could have asynch
 * polls calling this function due to sn_sal_switch_to_asynch but we can
 * ignore them until we register with the serial core stuffs.
 *
 */
static void sn_transmit_chars(struct sn_cons_port *port, int raw)
{
	int xmit_count, tail, head, loops, ii;