netx-serial.c

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/*
 * drivers/serial/netx-serial.c
 *
 * Copyright (c) 2005 Sascha Hauer <[e-mail]>, Pengutronix
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 *
 * 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
 */

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

#include <linux/device.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/hardware.h>
#include <asm/arch/netx-regs.h>

/* We've been assigned a range on the "Low-density serial ports" major */
#define SERIAL_NX_MAJOR	204
#define MINOR_START	170

#ifdef CONFIG_SERIAL_NETX_CONSOLE

enum uart_regs {
	UART_DR              = 0x00,
	UART_SR              = 0x04,
	UART_LINE_CR         = 0x08,
	UART_BAUDDIV_MSB     = 0x0c,
	UART_BAUDDIV_LSB     = 0x10,
	UART_CR              = 0x14,
	UART_FR              = 0x18,
	UART_IIR             = 0x1c,
	UART_ILPR            = 0x20,
	UART_RTS_CR          = 0x24,
	UART_RTS_LEAD        = 0x28,
	UART_RTS_TRAIL       = 0x2c,
	UART_DRV_ENABLE      = 0x30,
	UART_BRM_CR          = 0x34,
	UART_RXFIFO_IRQLEVEL = 0x38,
	UART_TXFIFO_IRQLEVEL = 0x3c,
};

#define SR_FE (1<<0)
#define SR_PE (1<<1)
#define SR_BE (1<<2)
#define SR_OE (1<<3)

#define LINE_CR_BRK       (1<<0)
#define LINE_CR_PEN       (1<<1)
#define LINE_CR_EPS       (1<<2)
#define LINE_CR_STP2      (1<<3)
#define LINE_CR_FEN       (1<<4)
#define LINE_CR_5BIT      (0<<5)
#define LINE_CR_6BIT      (1<<5)
#define LINE_CR_7BIT      (2<<5)
#define LINE_CR_8BIT      (3<<5)
#define LINE_CR_BITS_MASK (3<<5)

#define CR_UART_EN (1<<0)
#define CR_SIREN   (1<<1)
#define CR_SIRLP   (1<<2)
#define CR_MSIE    (1<<3)
#define CR_RIE     (1<<4)
#define CR_TIE     (1<<5)
#define CR_RTIE    (1<<6)
#define CR_LBE     (1<<7)

#define FR_CTS  (1<<0)
#define FR_DSR  (1<<1)
#define FR_DCD  (1<<2)
#define FR_BUSY (1<<3)
#define FR_RXFE (1<<4)
#define FR_TXFF (1<<5)
#define FR_RXFF (1<<6)
#define FR_TXFE (1<<7)

#define IIR_MIS (1<<0)
#define IIR_RIS (1<<1)
#define IIR_TIS (1<<2)
#define IIR_RTIS (1<<3)
#define IIR_MASK 0xf

#define RTS_CR_AUTO (1<<0)
#define RTS_CR_RTS  (1<<1)
#define RTS_CR_COUNT (1<<2)
#define RTS_CR_MOD2  (1<<3)
#define RTS_CR_RTS_POL (1<<4)
#define RTS_CR_CTS_CTR (1<<5)
#define RTS_CR_CTS_POL (1<<6)
#define RTS_CR_STICK   (1<<7)

#define UART_PORT_SIZE 0x40
#define DRIVER_NAME "netx-uart"

struct netx_port {
	struct uart_port	port;
};

static void netx_stop_tx(struct uart_port *port)
{
	unsigned int val;
	val = readl(port->membase + UART_CR);
	writel(val & ~CR_TIE,  port->membase + UART_CR);
}

static void netx_stop_rx(struct uart_port *port)
{
	unsigned int val;
	val = readl(port->membase + UART_CR);
	writel(val & ~CR_RIE,  port->membase + UART_CR);
}

static void netx_enable_ms(struct uart_port *port)
{
	unsigned int val;
	val = readl(port->membase + UART_CR);
	writel(val | CR_MSIE, port->membase + UART_CR);
}

static inline void netx_transmit_buffer(struct uart_port *port)
{
	struct circ_buf *xmit = &port->info->xmit;

	if (port->x_char) {
		writel(port->x_char, port->membase + UART_DR);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}

	if (uart_tx_stopped(port) || uart_circ_empty(xmit)) {
		netx_stop_tx(port);
		return;
	}

	do {
		/* send xmit->buf[xmit->tail]
		 * out the port here */
		writel(xmit->buf[xmit->tail], port->membase + UART_DR);
		xmit->tail = (xmit->tail + 1) &
		         (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if (uart_circ_empty(xmit))
			break;
	} while (!(readl(port->membase + UART_FR) & FR_TXFF));

	if (uart_circ_empty(xmit))
		netx_stop_tx(port);
}

static void netx_start_tx(struct uart_port *port)
{
	writel(
	    readl(port->membase + UART_CR) | CR_TIE, port->membase + UART_CR);

	if (!(readl(port->membase + UART_FR) & FR_TXFF))
		netx_transmit_buffer(port);
}

static unsigned int netx_tx_empty(struct uart_port *port)
{
	return readl(port->membase + UART_FR) & FR_BUSY ? 0 : TIOCSER_TEMT;
}

static void netx_txint(struct uart_port *port)
{
	struct circ_buf *xmit = &port->info->xmit;

	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		netx_stop_tx(port);
		return;
	}

	netx_transmit_buffer(port);

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

static void netx_rxint(struct uart_port *port)
{
	unsigned char rx, flg, status;
	struct tty_struct *tty = port->info->tty;

	while (!(readl(port->membase + UART_FR) & FR_RXFE)) {
		rx = readl(port->membase + UART_DR);
		flg = TTY_NORMAL;
		port->icount.rx++;
		status = readl(port->membase + UART_SR);
		if (status & SR_BE) {
			writel(0, port->membase + UART_SR);
			if (uart_handle_break(port))
				continue;
		}

		if (unlikely(status & (SR_FE | SR_PE | SR_OE))) {

			if (status & SR_PE)
				port->icount.parity++;
			else if (status & SR_FE)
				port->icount.frame++;
			if (status & SR_OE)
				port->icount.overrun++;

			status &= port->read_status_mask;

			if (status & SR_BE)
				flg = TTY_BREAK;
			else if (status & SR_PE)
				flg = TTY_PARITY;
			else if (status & SR_FE)
				flg = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(port, rx))
			continue;

		uart_insert_char(port, status, SR_OE, rx, flg);
	}

	tty_flip_buffer_push(tty);
	return;
}

static irqreturn_t netx_int(int irq, void *dev_id)
{
	struct uart_port *port = dev_id;
	unsigned long flags;
	unsigned char status;

	spin_lock_irqsave(&port->lock,flags);

	status = readl(port->membase + UART_IIR) & IIR_MASK;
	while (status) {
		if (status & IIR_RIS)
			netx_rxint(port);
		if (status & IIR_TIS)
			netx_txint(port);
		if (status & IIR_MIS) {
			if (readl(port->membase + UART_FR) & FR_CTS)
				uart_handle_cts_change(port, 1);
			else
				uart_handle_cts_change(port, 0);
		}
		writel(0, port->membase + UART_IIR);
		status = readl(port->membase + UART_IIR) & IIR_MASK;
	}

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

static unsigned int netx_get_mctrl(struct uart_port *port)
{
	unsigned int ret = TIOCM_DSR | TIOCM_CAR;

	if (readl(port->membase + UART_FR) & FR_CTS)
		ret |= TIOCM_CTS;

	return ret;
}

static void netx_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	unsigned int val;

	if (mctrl & TIOCM_RTS) {
		val = readl(port->membase + UART_RTS_CR);
		writel(val | RTS_CR_RTS, port->membase + UART_RTS_CR);
	}
}

static void netx_break_ctl(struct uart_port *port, int break_state)
{
	unsigned int line_cr;
	spin_lock_irq(&port->lock);

	line_cr = readl(port->membase + UART_LINE_CR);
	if (break_state != 0)
		line_cr |= LINE_CR_BRK;
	else
		line_cr &= ~LINE_CR_BRK;
	writel(line_cr, port->membase + UART_LINE_CR);

	spin_unlock_irq(&port->lock);
}

static int netx_startup(struct uart_port *port)
{
	int ret;

	ret = request_irq(port->irq, netx_int, 0,
			     DRIVER_NAME, port);
	if (ret) {
		dev_err(port->dev, "unable to grab irq%d\n",port->irq);
		goto exit;
	}

	writel(readl(port->membase + UART_LINE_CR) | LINE_CR_FEN,
		port->membase + UART_LINE_CR);

	writel(CR_MSIE | CR_RIE | CR_TIE | CR_RTIE | CR_UART_EN,
		port->membase + UART_CR);

exit:
	return ret;
}

static void netx_shutdown(struct uart_port *port)
{
	writel(0, port->membase + UART_CR) ;

	free_irq(port->irq, port);
}

static void
netx_set_termios(struct uart_port *port, struct ktermios *termios,
		   struct ktermios *old)
{
	unsigned int baud, quot;
	unsigned char old_cr;
	unsigned char line_cr = LINE_CR_FEN;
	unsigned char rts_cr = 0;

	switch (termios->c_cflag & CSIZE) {
	case CS5:
		line_cr |= LINE_CR_5BIT;
		break;
	case CS6:
		line_cr |= LINE_CR_6BIT;
		break;
	case CS7:
		line_cr |= LINE_CR_7BIT;
		break;
	case CS8:
		line_cr |= LINE_CR_8BIT;
		break;
	}

	if (termios->c_cflag & CSTOPB)
		line_cr |= LINE_CR_STP2;

	if (termios->c_cflag & PARENB) {
		line_cr |= LINE_CR_PEN;
		if (!(termios->c_cflag & PARODD))
			line_cr |= LINE_CR_EPS;
	}

	if (termios->c_cflag & CRTSCTS)
		rts_cr = RTS_CR_AUTO | RTS_CR_CTS_CTR | RTS_CR_RTS_POL;