dz.c

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/*
 * dz.c: Serial port driver for DECstations equipped
 *       with the DZ chipset.
 *
 * Copyright (C) 1998 Olivier A. D. Lebaillif
 *
 * Email: [e-mail]
 *
 * Copyright (C) 2004, 2006  Maciej W. Rozycki
 *
 * [31-AUG-98] triemer
 * Changed IRQ to use Harald's dec internals interrupts.h
 * removed base_addr code - moving address assignment to setup.c
 * Changed name of dz_init to rs_init to be consistent with tc code
 * [13-NOV-98] triemer fixed code to receive characters
 *    after patches by harald to irq code.
 * [09-JAN-99] triemer minor fix for schedule - due to removal of timeout
 *            field from "current" - somewhere between 2.1.121 and 2.1.131
 Qua Jun 27 15:02:26 BRT 2001
 * [27-JUN-2001] Arnaldo Carvalho de Melo <[e-mail]> - cleanups
 *
 * Parts (C) 1999 David Airlie, [e-mail]
 * [07-SEP-99] Bugfixes
 *
 * [06-Jan-2002] Russell King <[e-mail]>
 * Converted to new serial core
 */

#undef DEBUG_DZ

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

#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>

#include <asm/bootinfo.h>
#include <asm/dec/interrupts.h>
#include <asm/dec/kn01.h>
#include <asm/dec/kn02.h>
#include <asm/dec/machtype.h>
#include <asm/dec/prom.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include "dz.h"

static char *dz_name = "DECstation DZ serial driver version ";
static char *dz_version = "1.03";

struct dz_port {
	struct uart_port	port;
	unsigned int		cflag;
};

static struct dz_port dz_ports[DZ_NB_PORT];

/*
 * ------------------------------------------------------------
 * dz_in () and dz_out ()
 *
 * These routines are used to access the registers of the DZ
 * chip, hiding relocation differences between implementation.
 * ------------------------------------------------------------
 */

static inline unsigned short dz_in(struct dz_port *dport, unsigned offset)
{
	volatile unsigned short *addr =
		(volatile unsigned short *) (dport->port.membase + offset);

	return *addr;
}

static inline void dz_out(struct dz_port *dport, unsigned offset,
                          unsigned short value)
{
	volatile unsigned short *addr =
		(volatile unsigned short *) (dport->port.membase + offset);

	*addr = value;
}

/*
 * ------------------------------------------------------------
 * rs_stop () and rs_start ()
 *
 * These routines are called before setting or resetting
 * tty->stopped. They enable or disable transmitter interrupts,
 * as necessary.
 * ------------------------------------------------------------
 */

static void dz_stop_tx(struct uart_port *uport)
{
	struct dz_port *dport = (struct dz_port *)uport;
	unsigned short tmp, mask = 1 << dport->port.line;
	unsigned long flags;

	spin_lock_irqsave(&dport->port.lock, flags);
	tmp = dz_in(dport, DZ_TCR);	/* read the TX flag */
	tmp &= ~mask;			/* clear the TX flag */
	dz_out(dport, DZ_TCR, tmp);
	spin_unlock_irqrestore(&dport->port.lock, flags);
}

static void dz_start_tx(struct uart_port *uport)
{
	struct dz_port *dport = (struct dz_port *)uport;
	unsigned short tmp, mask = 1 << dport->port.line;
	unsigned long flags;

	spin_lock_irqsave(&dport->port.lock, flags);
	tmp = dz_in(dport, DZ_TCR);	/* read the TX flag */
	tmp |= mask;			/* set the TX flag */
	dz_out(dport, DZ_TCR, tmp);
	spin_unlock_irqrestore(&dport->port.lock, flags);
}

static void dz_stop_rx(struct uart_port *uport)
{
	struct dz_port *dport = (struct dz_port *)uport;
	unsigned long flags;

	spin_lock_irqsave(&dport->port.lock, flags);
	dport->cflag &= ~DZ_CREAD;
	dz_out(dport, DZ_LPR, dport->cflag | dport->port.line);
	spin_unlock_irqrestore(&dport->port.lock, flags);
}

static void dz_enable_ms(struct uart_port *port)
{
	/* nothing to do */
}

/*
 * ------------------------------------------------------------
 *
 * Here start the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * dz_interrupt.  They were separated out for readability's sake.
 *
 * Note: dz_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * dz_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 *
 *	make drivers/serial/dz.s
 *
 * and look at the resulting assemble code in dz.s.
 *
 * ------------------------------------------------------------
 */

/*
 * ------------------------------------------------------------
 * receive_char ()
 *
 * This routine deals with inputs from any lines.
 * ------------------------------------------------------------
 */
static inline void dz_receive_chars(struct dz_port *dport_in)
{
	struct dz_port *dport;
	struct tty_struct *tty = NULL;
	struct uart_icount *icount;
	int lines_rx[DZ_NB_PORT] = { [0 ... DZ_NB_PORT - 1] = 0 };
	unsigned short status;
	unsigned char ch, flag;
	int i;

	while ((status = dz_in(dport_in, DZ_RBUF)) & DZ_DVAL) {
		dport = &dz_ports[LINE(status)];
		tty = dport->port.info->tty;	/* point to the proper dev */

		ch = UCHAR(status);		/* grab the char */

		icount = &dport->port.icount;
		icount->rx++;

		flag = TTY_NORMAL;
		if (status & DZ_FERR) {		/* frame error */
			/*
			 * There is no separate BREAK status bit, so
			 * treat framing errors as BREAKs for Magic SysRq
			 * and SAK; normally, otherwise.
			 */
			if (uart_handle_break(&dport->port))
				continue;
			if (dport->port.flags & UPF_SAK)
				flag = TTY_BREAK;
			else
				flag = TTY_FRAME;
		} else if (status & DZ_OERR)	/* overrun error */
			flag = TTY_OVERRUN;
		else if (status & DZ_PERR)	/* parity error */
			flag = TTY_PARITY;

		/* keep track of the statistics */
		switch (flag) {
		case TTY_FRAME:
			icount->frame++;
			break;
		case TTY_PARITY:
			icount->parity++;
			break;
		case TTY_OVERRUN:
			icount->overrun++;
			break;
		case TTY_BREAK:
			icount->brk++;
			break;
		default:
			break;
		}

		if (uart_handle_sysrq_char(&dport->port, ch))
			continue;

		if ((status & dport->port.ignore_status_mask) == 0) {
			uart_insert_char(&dport->port,
					 status, DZ_OERR, ch, flag);
			lines_rx[LINE(status)] = 1;
		}
	}
	for (i = 0; i < DZ_NB_PORT; i++)
		if (lines_rx[i])
			tty_flip_buffer_push(dz_ports[i].port.info->tty);
}

/*
 * ------------------------------------------------------------
 * transmit_char ()
 *
 * This routine deals with outputs to any lines.
 * ------------------------------------------------------------
 */
static inline void dz_transmit_chars(struct dz_port *dport_in)
{
	struct dz_port *dport;
	struct circ_buf *xmit;
	unsigned short status;
	unsigned char tmp;

	status = dz_in(dport_in, DZ_CSR);
	dport = &dz_ports[LINE(status)];
	xmit = &dport->port.info->xmit;

	if (dport->port.x_char) {		/* XON/XOFF chars */
		dz_out(dport, DZ_TDR, dport->port.x_char);
		dport->port.icount.tx++;
		dport->port.x_char = 0;
		return;
	}
	/* If nothing to do or stopped or hardware stopped. */
	if (uart_circ_empty(xmit) || uart_tx_stopped(&dport->port)) {
		dz_stop_tx(&dport->port);
		return;
	}

	/*
	 * If something to do... (remember the dz has no output fifo,
	 * so we go one char at a time) :-<
	 */
	tmp = xmit->buf[xmit->tail];
	xmit->tail = (xmit->tail + 1) & (DZ_XMIT_SIZE - 1);
	dz_out(dport, DZ_TDR, tmp);
	dport->port.icount.tx++;

	if (uart_circ_chars_pending(xmit) < DZ_WAKEUP_CHARS)
		uart_write_wakeup(&dport->port);

	/* Are we are done. */
	if (uart_circ_empty(xmit))
		dz_stop_tx(&dport->port);
}

/*
 * ------------------------------------------------------------
 * check_modem_status()
 *
 * DS 3100 & 5100: Only valid for the MODEM line, duh!
 * DS 5000/200: Valid for the MODEM and PRINTER line.
 * ------------------------------------------------------------
 */
static inline void check_modem_status(struct dz_port *dport)
{
	/*
	 * FIXME:
	 * 1. No status change interrupt; use a timer.
	 * 2. Handle the 3100/5000 as appropriate. --macro
	 */
	unsigned short status;

	/* If not the modem line just return.  */
	if (dport->port.line != DZ_MODEM)
		return;

	status = dz_in(dport, DZ_MSR);

	/* it's easy, since DSR2 is the only bit in the register */
	if (status)
		dport->port.icount.dsr++;
}

/*
 * ------------------------------------------------------------
 * dz_interrupt ()
 *
 * this is the main interrupt routine for the DZ chip.
 * It deals with the multiple ports.
 * ------------------------------------------------------------
 */
static irqreturn_t dz_interrupt(int irq, void *dev)
{
	struct dz_port *dport = (struct dz_port *)dev;
	unsigned short status;

	/* get the reason why we just got an irq */
	status = dz_in(dport, DZ_CSR);

	if ((status & (DZ_RDONE | DZ_RIE)) == (DZ_RDONE | DZ_RIE))
		dz_receive_chars(dport);

	if ((status & (DZ_TRDY | DZ_TIE)) == (DZ_TRDY | DZ_TIE))
		dz_transmit_chars(dport);

	return IRQ_HANDLED;
}

/*
 * -------------------------------------------------------------------
 * Here ends the DZ interrupt routines.
 * -------------------------------------------------------------------
 */

static unsigned int dz_get_mctrl(struct uart_port *uport)
{
	/*
	 * FIXME: Handle the 3100/5000 as appropriate. --macro
	 */
	struct dz_port *dport = (struct dz_port *)uport;
	unsigned int mctrl = TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;

	if (dport->port.line == DZ_MODEM) {
		if (dz_in(dport, DZ_MSR) & DZ_MODEM_DSR)
			mctrl &= ~TIOCM_DSR;
	}

	return mctrl;
}

static void dz_set_mctrl(struct uart_port *uport, unsigned int mctrl)
{
	/*
	 * FIXME: Handle the 3100/5000 as appropriate. --macro
	 */
	struct dz_port *dport = (struct dz_port *)uport;
	unsigned short tmp;

	if (dport->port.line == DZ_MODEM) {
		tmp = dz_in(dport, DZ_TCR);
		if (mctrl & TIOCM_DTR)
			tmp &= ~DZ_MODEM_DTR;
		else
			tmp |= DZ_MODEM_DTR;
		dz_out(dport, DZ_TCR, tmp);
	}
}

/*
 * -------------------------------------------------------------------
 * startup ()
 *
 * various initialization tasks
 * -------------------------------------------------------------------
 */
static int dz_startup(struct uart_port *uport)
{
	struct dz_port *dport = (struct dz_port *)uport;
	unsigned long flags;
	unsigned short tmp;

	spin_lock_irqsave(&dport->port.lock, flags);

	/* enable the interrupt and the scanning */
	tmp = dz_in(dport, DZ_CSR);
	tmp |= DZ_RIE | DZ_TIE | DZ_MSE;
	dz_out(dport, DZ_CSR, tmp);

	spin_unlock_irqrestore(&dport->port.lock, flags);

	return 0;
}

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