sa1100.c

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/*
 *  linux/drivers/char/serial_sa1100.c
 *
 *  Driver for SA11x0 serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  $Id: sa1100.c,v 1.14.2.4 2002/10/24 09:53:25 rmk Exp $
 *
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/circ_buf.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/bitops.h>
#include <asm/hardware.h>
#include <asm/mach/serial_sa1100.h>

#if defined(CONFIG_SERIAL_SA1100_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>

/* We've been assigned a range on the "Low-density serial ports" major */
#define SERIAL_SA1100_MAJOR	204
#define CALLOUT_SA1100_MAJOR	205
#define MINOR_START		5

#define NR_PORTS		3

#define SA1100_ISR_PASS_LIMIT	256

/*
 * Convert from ignore_status_mask or read_status_mask to UTSR[01]
 */
#define SM_TO_UTSR0(x)	((x) & 0xff)
#define SM_TO_UTSR1(x)	((x) >> 8)
#define UTSR0_TO_SM(x)	((x))
#define UTSR1_TO_SM(x)	((x) << 8)

#define UART_GET_UTCR0(port)		__raw_readl((port)->membase + UTCR0)
#define UART_GET_UTCR1(port)		__raw_readl((port)->membase + UTCR1)
#define UART_GET_UTCR2(port)		__raw_readl((port)->membase + UTCR2)
#define UART_GET_UTCR3(port)		__raw_readl((port)->membase + UTCR3)
#define UART_GET_UTSR0(port)		__raw_readl((port)->membase + UTSR0)
#define UART_GET_UTSR1(port)		__raw_readl((port)->membase + UTSR1)
#define UART_GET_CHAR(port)		__raw_readl((port)->membase + UTDR)

#define UART_PUT_UTCR0(port,v)		__raw_writel((v),(port)->membase + UTCR0)
#define UART_PUT_UTCR1(port,v)		__raw_writel((v),(port)->membase + UTCR1)
#define UART_PUT_UTCR2(port,v)		__raw_writel((v),(port)->membase + UTCR2)
#define UART_PUT_UTCR3(port,v)		__raw_writel((v),(port)->membase + UTCR3)
#define UART_PUT_UTSR0(port,v)		__raw_writel((v),(port)->membase + UTSR0)
#define UART_PUT_UTSR1(port,v)		__raw_writel((v),(port)->membase + UTSR1)
#define UART_PUT_CHAR(port,v)		__raw_writel((v),(port)->membase + UTDR)

/*
 * This is the size of our serial port register set.
 */
#define UART_PORT_SIZE	0x24

static struct tty_driver normal, callout;
static struct tty_struct *sa1100_table[NR_PORTS];
static struct termios *sa1100_termios[NR_PORTS], *sa1100_termios_locked[NR_PORTS];
static int (*sa1100_open)(struct uart_port *, struct uart_info *);
static void (*sa1100_close)(struct uart_port *, struct uart_info *);
#ifdef SUPPORT_SYSRQ
static struct console sa1100_console;
#endif

/*
 * interrupts disabled on entry
 */
static void sa1100_stop_tx(struct uart_port *port, u_int from_tty)
{
	u32 utcr3 = UART_GET_UTCR3(port);
	UART_PUT_UTCR3(port, utcr3 & ~UTCR3_TIE);
	port->read_status_mask &= ~UTSR0_TO_SM(UTSR0_TFS);
}

/*
 * interrupts may not be disabled on entry
 */
static void sa1100_start_tx(struct uart_port *port, u_int nonempty, u_int from_tty)
{
	if (nonempty) {
		unsigned long flags;
		u32 utcr3;

		local_irq_save(flags);
		utcr3 = UART_GET_UTCR3(port);
		port->read_status_mask |= UTSR0_TO_SM(UTSR0_TFS);
		UART_PUT_UTCR3(port, utcr3 | UTCR3_TIE);
		local_irq_restore(flags);
	}
}

/*
 * Interrupts enabled
 */
static void sa1100_stop_rx(struct uart_port *port)
{
	u32 utcr3 = UART_GET_UTCR3(port);
	UART_PUT_UTCR3(port, utcr3 & ~UTCR3_RIE);
}

/*
 * No modem control lines
 */
static void sa1100_enable_ms(struct uart_port *port)
{
}

static void
sa1100_rx_chars(struct uart_info *info, struct pt_regs *regs)
{
	struct tty_struct *tty = info->tty;
	unsigned int status, ch, flg, ignored = 0;
	struct uart_port *port = info->port;

	status = UTSR1_TO_SM(UART_GET_UTSR1(port)) | UTSR0_TO_SM(UART_GET_UTSR0(port));
	while (status & UTSR1_TO_SM(UTSR1_RNE)) {
		ch = UART_GET_CHAR(port);

		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			goto ignore_char;
		port->icount.rx++;

		flg = TTY_NORMAL;

		/*
		 * note that the error handling code is
		 * out of the main execution path
		 */
		if (status & UTSR1_TO_SM(UTSR1_PRE | UTSR1_FRE | UTSR1_ROR))
			goto handle_error;

		if (uart_handle_sysrq_char(info, ch, regs))
			goto ignore_char;

	error_return:
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
	ignore_char:
		status = UTSR1_TO_SM(UART_GET_UTSR1(port)) | UTSR0_TO_SM(UART_GET_UTSR0(port));
	}
out:
	tty_flip_buffer_push(tty);
	return;

handle_error:
	if (status & UTSR1_TO_SM(UTSR1_PRE))
		port->icount.parity++;
	else if (status & UTSR1_TO_SM(UTSR1_FRE))
		port->icount.frame++;
	if (status & UTSR1_TO_SM(UTSR1_ROR))
		port->icount.overrun++;

	if (status & port->ignore_status_mask) {
		if (++ignored > 100)
			goto out;
		goto ignore_char;
	}

	status &= port->read_status_mask;

	if (status & UTSR1_TO_SM(UTSR1_PRE))
		flg = TTY_PARITY;
	else if (status & UTSR1_TO_SM(UTSR1_FRE))
		flg = TTY_FRAME;

	if (status & UTSR1_TO_SM(UTSR1_ROR)) {
		/*
		 * overrun does *not* affect the character
		 * we read from the FIFO
		 */
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			goto ignore_char;
		ch = 0;
		flg = TTY_OVERRUN;
	}
#ifdef SUPPORT_SYSRQ
	info->sysrq = 0;
#endif
	goto error_return;
}

static void sa1100_tx_chars(struct uart_info *info)
{
	struct uart_port *port = info->port;

	if (port->x_char) {
		UART_PUT_CHAR(port, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}
	if (info->xmit.head == info->xmit.tail
	    || info->tty->stopped
	    || info->tty->hw_stopped) {
		sa1100_stop_tx(info->port, 0);
		return;
	}

	/*
	 * Tried using FIFO (not checking TNF) for fifo fill:
	 * still had the '4 bytes repeated' problem.
	 */
	while (UART_GET_UTSR1(port) & UTSR1_TNF) {
		UART_PUT_CHAR(port, info->xmit.buf[info->xmit.tail]);
		info->xmit.tail = (info->xmit.tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if (info->xmit.head == info->xmit.tail)
			break;
	}

	if (CIRC_CNT(info->xmit.head, info->xmit.tail, UART_XMIT_SIZE) <
			WAKEUP_CHARS)
		uart_event(info, EVT_WRITE_WAKEUP);

	if (info->xmit.head == info->xmit.tail)
		sa1100_stop_tx(info->port, 0);
}

static void sa1100_int(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_info *info = dev_id;
	struct uart_port *port = info->port;
	unsigned int status, pass_counter = 0;

	status = UART_GET_UTSR0(port);
	status &= (SM_TO_UTSR0(port->read_status_mask) | ~UTSR0_TFS);
	do {
		if (status & (UTSR0_RFS | UTSR0_RID)) {
			/* Clear the receiver idle bit, if set */
			if (status & UTSR0_RID)
				UART_PUT_UTSR0(port, UTSR0_RID);
			sa1100_rx_chars(info, regs);
		}

		/* Clear the relevent break bits */
		if (status & (UTSR0_RBB | UTSR0_REB))
			UART_PUT_UTSR0(port, status & (UTSR0_RBB | UTSR0_REB));

		if (status & UTSR0_RBB)
			port->icount.brk++;

		if (status & UTSR0_REB) {
#ifdef SUPPORT_SYSRQ
			if (port->line == sa1100_console.index &&
			    !info->sysrq) {
				info->sysrq = jiffies + HZ*5;
			}
#endif
		}
		if (status & UTSR0_TFS)
			sa1100_tx_chars(info);
		if (pass_counter++ > SA1100_ISR_PASS_LIMIT)
			break;
		status = UART_GET_UTSR0(port);
		status &= (SM_TO_UTSR0(port->read_status_mask) | ~UTSR0_TFS);
	} while (status & (UTSR0_TFS | UTSR0_RFS | UTSR0_RID));
}

/*
 * Return TIOCSER_TEMT when transmitter is not busy.
 */
static u_int sa1100_tx_empty(struct uart_port *port)
{
	return UART_GET_UTSR1(port) & UTSR1_TBY ? 0 : TIOCSER_TEMT;
}

static u_int sa1100_get_mctrl(struct uart_port *port)
{
	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
}

static void sa1100_set_mctrl(struct uart_port *port, u_int mctrl)
{
}

/*
 * Interrupts always disabled.
 */
static void sa1100_break_ctl(struct uart_port *port, int break_state)
{
	u_int utcr3;

	utcr3 = UART_GET_UTCR3(port);
	if (break_state == -1)
		utcr3 |= UTCR3_BRK;
	else
		utcr3 &= ~UTCR3_BRK;
	UART_PUT_UTCR3(port, utcr3);
}

static int sa1100_startup(struct uart_port *port, struct uart_info *info)
{
	int retval;

	/*
	 * Allocate the IRQ
	 */
	retval = request_irq(port->irq, sa1100_int, 0, "serial_sa1100", info);
	if (retval)
		return retval;

	/*
	 * If there is a specific "open" function (to register
	 * control line interrupts)
	 */
	if (sa1100_open) {
		retval = sa1100_open(port, info);
		if (retval) {
			free_irq(port->irq, info);
			return retval;
		}
	}

	/*
	 * Finally, clear and enable interrupts
	 */
	UART_PUT_UTSR0(port, -1);
	UART_PUT_UTCR3(port, UTCR3_RXE | UTCR3_TXE | UTCR3_RIE);

	return 0;
}

static void sa1100_shutdown(struct uart_port *port, struct uart_info *info)
{
	/*
	 * Free the interrupt
	 */
	free_irq(port->irq, info);

	/*
	 * If there is a specific "close" function (to unregister
	 * control line interrupts)
	 */
	if (sa1100_close)
		sa1100_close(port, info);

	/*
	 * Disable all interrupts, port and break condition.
	 */
	UART_PUT_UTCR3(port, 0);
}

static void sa1100_change_speed(struct uart_port *port, u_int cflag, u_int iflag, u_int quot)
{
	unsigned long flags;
	u_int utcr0, old_utcr3;