/*
 *  linux/drivers/char/serial_amba.c
 *
 *  Driver for AMBA serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright 1999 ARM Limited
 *  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
 *
 *
 * This is a generic driver for ARM AMBA-type serial ports.  They
 * have a lot of 16550-like features, but are not register compatable.
 * Note that although they do have CTS, DCD and DSR inputs, they do
 * not have an RI input, nor do they have DTR or RTS outputs.  If
 * required, these have to be supplied via some other means (eg, GPIO)
 * and hooked into this driver.
 *
 * This could very easily become a generic serial driver for dumb UARTs
 * (eg, {82,16x}50, 21285, SA1100).
 */
#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 "serial_core.h"

#include <asm/hardware/serial_amba.h>

#define UART_NR		2

#define SERIAL_AMBA_NAME	"ttyAM"
#define SERIAL_AMBA_MAJOR	204
#define SERIAL_AMBA_MINOR	16
#define SERIAL_AMBA_NR		UART_NR

#define CALLOUT_AMBA_NAME	"cuaam"
#define CALLOUT_AMBA_MAJOR	205
#define CALLOUT_AMBA_MINOR	16
#define CALLOUT_AMBA_NR		UART_NR

static struct tty_driver normal, callout;
static struct tty_struct *amba_table[UART_NR];
static struct termios *amba_termios[UART_NR], *amba_termios_locked[UART_NR];
static struct uart_state amba_state[UART_NR];

#define AMBA_ISR_PASS_LIMIT	256

/*
 * Access macros for the AMBA UARTs
 */
#define UART_GET_INT_STATUS(p)	readb((p)->base + AMBA_UARTIIR)
#define UART_PUT_ICR(p, c)	writel((c), (p)->base + AMBA_UARTICR)
#define UART_GET_FR(p)		readb((p)->base + AMBA_UARTFR)
#define UART_GET_CHAR(p)	readb((p)->base + AMBA_UARTDR)
#define UART_PUT_CHAR(p, c)	writel((c), (p)->base + AMBA_UARTDR)
#define UART_GET_RSR(p)		readb((p)->base + AMBA_UARTRSR)
#define UART_GET_CR(p)		readb((p)->base + AMBA_UARTCR)
#define UART_PUT_CR(p,c)	writel((c), (p)->base + AMBA_UARTCR)
#define UART_GET_LCRL(p)	readb((p)->base + AMBA_UARTLCR_L)
#define UART_PUT_LCRL(p,c)	writel((c), (p)->base + AMBA_UARTLCR_L)
#define UART_GET_LCRM(p)	readb((p)->base + AMBA_UARTLCR_M)
#define UART_PUT_LCRM(p,c)	writel((c), (p)->base + AMBA_UARTLCR_M)
#define UART_GET_LCRH(p)	readb((p)->base + AMBA_UARTLCR_H)
#define UART_PUT_LCRH(p,c)	writel((c), (p)->base + AMBA_UARTLCR_H)
#define UART_RX_DATA(s)		(((s) & AMBA_UARTFR_RXFE) == 0)
#define UART_TX_READY(s)	(((s) & AMBA_UARTFR_TXFF) == 0)
#define UART_TX_EMPTY(p)	((UART_GET_FR(p) & AMBA_UARTFR_TMSK) == 0)

static void ambauart_stop_tx(struct uart_port *port, u_int from_tty)
{
	unsigned int cr;

	cr = UART_GET_CR(port);
	cr &= ~AMBA_UARTCR_TIE;
	UART_PUT_CR(port, cr);
}

static void ambauart_start_tx(struct uart_port *port, u_int nonempty, u_int from_tty)
{
	if (nonempty) {
		unsigned int cr;

		cr = UART_GET_CR(port);
		cr |= AMBA_UARTCR_TIE;
		UART_PUT_CR(port, cr);
	}
}

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

	cr = UART_GET_CR(port);
	cr &= ~(AMBA_UARTCR_RIE | AMBA_UARTCR_RTIE);
	UART_PUT_CR(port, cr);
}

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

	cr = UART_GET_CR(port);
	cr |= AMBA_UARTCR_MSIE;
	UART_PUT_CR(port, cr);
}

static void
#ifdef SUPPORT_SYSRQ
ambauart_rx_chars(struct uart_info *info, struct pt_regs *regs)
#else
ambauart_rx_chars(struct uart_info *info)
#endif
{
	struct tty_struct *tty = info->tty;
	unsigned int status, ch, rsr, flg, ignored = 0;
	struct uart_icount *icount = &info->state->icount;
	struct uart_port *port = info->port;

	status = UART_GET_FR(port);
	while (UART_RX_DATA(status)) {
		ch = UART_GET_CHAR(port);

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

		flg = TTY_NORMAL;

		/*
		 * Note that the error handling code is
		 * out of the main execution path
		 */
		rsr = UART_GET_RSR(port);
		if (rsr & AMBA_UARTRSR_ANY)
			goto handle_error;
#ifdef SUPPORT_SYSRQ
		if (info->sysrq) {
			if (ch && time_before(jiffies, info->sysrq)) {
				handle_sysrq(ch, regs, NULL, NULL);
				info->sysrq = 0;
				goto ignore_char;
			}
			info->sysrq = 0;
		}
#endif
	error_return:
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
	ignore_char:
		status = UART_GET_FR(port);
	}
out:
	tty_flip_buffer_push(tty);
	return;

handle_error:
	if (rsr & AMBA_UARTRSR_BE) {
		rsr &= ~(AMBA_UARTRSR_FE | AMBA_UARTRSR_PE);
		icount->brk++;

#ifdef SUPPORT_SYSRQ
		if (info->state->line == uart_cons.index) {
			if (!info->sysrq) {
				info->sysrq = jiffies + HZ*5;
				goto ignore_char;
			}
		}
#endif
	} else if (rsr & AMBA_UARTRSR_PE)
		icount->parity++;
	else if (rsr & AMBA_UARTRSR_FE)
		icount->frame++;
	if (rsr & AMBA_UARTRSR_OE)
		icount->overrun++;

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

	if (rsr & AMBA_UARTRSR_BE)
		flg = TTY_BREAK;
	else if (rsr & AMBA_UARTRSR_PE)
		flg = TTY_PARITY;
	else if (rsr & AMBA_UARTRSR_FE)
		flg = TTY_FRAME;

	if (rsr & AMBA_UARTRSR_OE) {
		/*
		 * CHECK: does overrun affect the current character?
		 * ASSUMPTION: it does not.
		 */
		*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 ambauart_tx_chars(struct uart_info *info)
{
	struct uart_port *port = info->port;
	int count;

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

	count = port->fifosize >> 1;
	do {
		UART_PUT_CHAR(port, info->xmit.buf[info->xmit.tail]);
		info->xmit.tail = (info->xmit.tail + 1) & (UART_XMIT_SIZE - 1);
		info->state->icount.tx++;
		if (info->xmit.head == info->xmit.tail)
			break;
	} while (--count > 0);

	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)
		ambauart_stop_tx(info->port, 0);
}

static void ambauart_modem_status(struct uart_info *info)
{
	unsigned int status, delta;
	struct uart_icount *icount = &info->state->icount;

	UART_PUT_ICR(info->port, 0);

	status = UART_GET_FR(info->port) & AMBA_UARTFR_MODEM_ANY;

	delta = status ^ info->port->old_status;
	info->port->old_status = status;

	if (!delta)
		return;

	if (delta & AMBA_UARTFR_DCD) {
		icount->dcd++;
#ifdef CONFIG_HARD_PPS
		if ((info->flags & ASYNC_HARDPPS_CD) &&
		    (status & AMBA_UARTFR_DCD)
			hardpps();
#endif
		if (info->flags & ASYNC_CHECK_CD) {
			if (status & AMBA_UARTFR_DCD)
				wake_up_interruptible(&info->open_wait);
			else if (!((info->flags & ASYNC_CALLOUT_ACTIVE) &&
				   (info->flags & ASYNC_CALLOUT_NOHUP))) {
				if (info->tty)
					tty_hangup(info->tty);
			}
		}
	}

	if (delta & AMBA_UARTFR_DSR)
		icount->dsr++;

	if (delta & AMBA_UARTFR_CTS) {
		icount->cts++;

		if (info->flags & ASYNC_CTS_FLOW) {
			status &= AMBA_UARTFR_CTS;

			if (info->tty->hw_stopped) {
				if (status) {
					info->tty->hw_stopped = 0;
					info->ops->start_tx(info->port, 1, 0);
					uart_event(info, EVT_WRITE_WAKEUP);
				}
			} else {
				if (!status) {
					info->tty->hw_stopped = 1;
					info->ops->stop_tx(info->port, 0);
				}
			}
		}
	}
	wake_up_interruptible(&info->delta_msr_wait);

}

static void ambauart_int(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_info *info = dev_id;
	unsigned int status, pass_counter = 0;

	status = UART_GET_INT_STATUS(info->port);
	do {
		/*
		 * FIXME: what about clearing the interrupts?
		 */

		if (status & (AMBA_UARTIIR_RTIS | AMBA_UARTIIR_RIS))
#ifdef SUPPORT_SYSRQ
			ambauart_rx_chars(info, regs);
#else
			ambauart_rx_chars(info);
#endif
		if (status & AMBA_UARTIIR_TIS)
			ambauart_tx_chars(info);
		if (status & AMBA_UARTIIR_MIS)
			ambauart_modem_status(info);
		if (pass_counter++ > AMBA_ISR_PASS_LIMIT)
			break;

		status = UART_GET_INT_STATUS(info->port);
	} while (status & (AMBA_UARTIIR_RTIS | AMBA_UARTIIR_RIS | AMBA_UARTIIR_TIS));
}

static u_int ambauart_tx_empty(struct uart_port *port)
{
	return UART_GET_FR(port) & AMBA_UARTFR_BUSY ? 0 : TIOCSER_TEMT;
}

static int ambauart_get_mctrl(struct uart_port *port)
{
	unsigned int result = 0;
	unsigned int status;

	status = UART_GET_FR(port);
	if (status & AMBA_UARTFR_DCD)
		result |= TIOCM_CAR;
	if (status & AMBA_UARTFR_DSR)
		result |= TIOCM_DSR;
	if (status & AMBA_UARTFR_CTS)
		result |= TIOCM_CTS;

	return result;
}

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

static void ambauart_break_ctl(struct uart_port *port, int break_state)
{
	unsigned int lcr_h;

	lcr_h = UART_GET_LCRH(port);
	if (break_state == -1)
		lcr_h |= AMBA_UARTLCR_H_BRK;
	else
		lcr_h &= ~AMBA_UARTLCR_H_BRK;
	UART_PUT_LCRH(port, lcr_h);
}

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

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

	port->ops->set_mctrl(port, info->mctrl);

	/*
	 * initialise the old status of the modem signals
	 */
	port->old_status = UART_GET_FR(port) & AMBA_UARTFR_MODEM_ANY;

	/*
	 * Finally, enable interrupts
	 */
	UART_PUT_CR(port, AMBA_UARTCR_UARTEN | AMBA_UARTCR_RIE |
			  AMBA_UARTCR_RTIE);

	return 0;
}

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

	/*
	 * disable all interrupts, disable the port
	 */
	UART_PUT_CR(port, 0);

	/* disable break condition and fifos */
	UART_PUT_LCRH(port, UART_GET_LCRH(port) &
		~(AMBA_UARTLCR_H_BRK | AMBA_UARTLCR_H_FEN));
}

static void ambauart_change_speed(struct uart_port *port, u_int cflag, u_int iflag, u_int quot)
{
	u_int lcr_h, old_cr;
	unsigned long flags;

#if DEBUG
	printk("ambauart_set_cflag(0x%x) called\n", cflag);
#endif
	/* byte size and parity */
	switch (cflag & CSIZE) {
	case CS5: lcr_h = AMBA_UARTLCR_H_WLEN_5; break;
	case CS6: lcr_h = AMBA_UARTLCR_H_WLEN_6; break;
	case CS7: lcr_h = AMBA_UARTLCR_H_WLEN_7; break;
	default:  lcr_h = AMBA_UARTLCR_H_WLEN_8; break; // CS8
	}
	if (cflag & CSTOPB)
		lcr_h |= AMBA_UARTLCR_H_STP2;
	if (cflag & PARENB) {
		lcr_h |= AMBA_UARTLCR_H_PEN;
		if (!(cflag & PARODD))
			lcr_h |= AMBA_UARTLCR_H_EPS;
	}
	if (port->fifosize > 1)
		lcr_h |= AMBA_UARTLCR_H_FEN;

	port->read_status_mask = AMBA_UARTRSR_OE;
	if (iflag & INPCK)
		port->read_status_mask |= AMBA_UARTRSR_FE | AMBA_UARTRSR_PE;
	if (iflag & (BRKINT | PARMRK))
		port->read_status_mask |= AMBA_UARTRSR_BE;

	/*
	 * Characters to ignore
	 */
	port->ignore_status_mask = 0;
	if (iflag & IGNPAR)
		port->ignore_status_mask |= AMBA_UARTRSR_FE | AMBA_UARTRSR_PE;
	if (iflag & IGNBRK) {
		port->ignore_status_mask |= AMBA_UARTRSR_BE;
		/*
		 * If we're ignoring parity and break indicators,
		 * ignore overruns to (for real raw support).
		 */
		if (iflag & IGNPAR)
			port->ignore_status_mask |= AMBA_UARTRSR_OE;
	}

	/* first, disable everything */
	save_flags(flags); cli();
	old_cr = UART_GET_CR(port) &= ~AMBA_UARTCR_MSIE;

	if ((port->flags & ASYNC_HARDPPS_CD) ||
	    (cflag & CRTSCTS) || !(cflag & CLOCAL))
		old_cr |= AMBA_UARTCR_MSIE;

	UART_PUT_CR(port, 0);

	/* Set baud rate */
	UART_PUT_LCRM(port, ((quot & 0xf00) >> 8));
	UART_PUT_LCRL(port, (quot & 0xff));

	/*
	 * ----------v----------v----------v----------v-----
	 * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
	 * ----------^----------^----------^----------^-----
	 */
	UART_PUT_LCRH(port, lcr_h);
	UART_PUT_CR(port, old_cr);

	restore_flags(flags);
}

static struct uart_ops amba_pops = {
	tx_empty:	ambauart_tx_empty,
	set_mctrl:	ambauart_set_mctrl_null,
	get_mctrl:	ambauart_get_mctrl,
	stop_tx:	ambauart_stop_tx,
	start_tx:	ambauart_start_tx,
	stop_rx:	ambauart_stop_rx,
	enable_ms:	ambauart_enable_ms,
	break_ctl:	ambauart_break_ctl,
	startup:	ambauart_startup,
	shutdown:	ambauart_shutdown,
	change_speed:	ambauart_change_speed,
};

static struct uart_port amba_ports[UART_NR] = {
	{
		base:		IO_ADDRESS(INTEGRATOR_UART0_BASE),
		irq:		IRQ_UARTINT0,
		uartclk:	14745600,
		fifosize:	16,
		ops:		&amba_pops,
	},
	{
		base:		IO_ADDRESS(INTEGRATOR_UART1_BASE),
		irq:		IRQ_UARTINT1,
		uartclk:	14745600,
		fifosize:	16,
		ops:		&amba_pops,
	}
};

#ifdef CONFIG_SERIAL_AMBA_CONSOLE
#ifdef used_and_not_const_char_pointer
static int ambauart_console_read(struct uart_port *port, char *s, u_int count)
{
	unsigned int status;
	int c;
#if DEBUG
	printk("ambauart_console_read() called\n");
#endif

	c = 0;
	while (c < count) {
		status = UART_GET_FR(port);
		if (UART_RX_DATA(status)) {
			*s++ = UART_GET_CHAR(port);
			c++;
		} else {
			// nothing more to get, return
			return c;
		}
	}
	// return the count
	return c;
}
#endif

static void ambauart_console_write(struct console *co, const char *s, u_int count)
{
	struct uart_port *port = amba_ports + co->index;
	unsigned int status, old_cr;
	int i;

	/*
	 *	First save the CR then disable the interrupts
	 */
	old_cr = UART_GET_CR(port);
	UART_PUT_CR(port, AMBA_UARTCR_UARTEN);

	/*
	 *	Now, do each character
	 */
	for (i = 0; i < count; i++) {
		do {
			status = UART_GET_FR(port);
		} while (!UART_TX_READY(status));
		UART_PUT_CHAR(port, s[i]);
		if (s[i] == '\n') {
			do {
				status = UART_GET_FR(port);
			} while (!UART_TX_READY(status));
			UART_PUT_CHAR(port, '\r');
		}
	}

	/*
	 *	Finally, wait for transmitter to become empty
	 *	and restore the TCR
	 */
	do {
		status = UART_GET_FR(port);
	} while (status & AMBA_UARTFR_BUSY);
	UART_PUT_CR(port, old_cr);
}

static kdev_t ambauart_console_device(struct console *co)
{
	return MKDEV(SERIAL_AMBA_MAJOR, SERIAL_AMBA_MINOR + co->index);
}

static int ambauart_console_wait_key(struct console *co)
{
	struct uart_port *port = amba_ports + co->index;
	unsigned int status;

	do {
		status = UART_GET_FR(port);
	} while (!UART_RX_DATA(status));
	return UART_GET_CHAR(port);
}

static void __init
ambauart_console_get_options(struct uart_port *port, int *baud, int *parity, int *bits)
{
	if (UART_GET_CR(port) & AMBA_UARTCR_UARTEN) {
		u_int lcr_h, quot;
		lcr_h = UART_GET_LCRH(port);

		*parity = 'n';
		if (lcr_h & AMBA_UARTLCR_H_PEN) {
			if (lcr_h & AMBA_UARTLCR_H_EPS)
				*parity = 'e';
			else
				*parity = 'o';
		}

		if ((lcr_h & 0x60) == AMBA_UARTLCR_H_WLEN_7)
			*bits = 7;
		else
			*bits = 8;

		quot = UART_GET_LCRL(port) | UART_GET_LCRM(port) << 8;
		*baud = port->uartclk / (16 * (quot + 1));
	}
}

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

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

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

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

static struct console amba_console = {
	write:		ambauart_console_write,
#ifdef used_and_not_const_char_pointer
	read:		ambauart_console_read,
#endif
	device:		ambauart_console_device,
	wait_key:	ambauart_console_wait_key,
	setup:		ambauart_console_setup,
	flags:		CON_PRINTBUFFER,
	index:		-1,
};

void __init ambauart_console_init(void)
{
	register_console(&amba_console);
}

#define AMBA_CONSOLE	&amba_console
#else
#define AMBA_CONSOLE	NULL
#endif

static struct uart_register amba_reg = {
	normal_major:		SERIAL_AMBA_MAJOR,
	normal_name:		SERIAL_AMBA_NAME,
	normal_driver:		&normal,
	callout_major:		CALLOUT_AMBA_MAJOR,
	callout_name:		CALLOUT_AMBA_NAME,
	callout_driver:		&callout,
	table:			amba_table,
	termios:		amba_termios,
	termios_locked:		amba_termios_locked,
	minor:			SERIAL_AMBA_MINOR,
	nr:			UART_NR,
	state:			amba_state,
	port:			amba_ports,
	cons:			AMBA_CONSOLE,
};

static int __init ambauart_init(void)
{
	return uart_register_port(&amba_reg);
}

__initcall(ambauart_init);
