drivers/serial/amba-pl011.c



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/*
 *  linux/drivers/char/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 compatible.
 * 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.
 */

#if defined(CONFIG_SERIAL_AMBA_PL011_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

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

#include <asm/io.h>
#include <asm/sizes.h>

#define UART_NR			14

#define SERIAL_AMBA_MAJOR	204
#define SERIAL_AMBA_MINOR	64
#define SERIAL_AMBA_NR		UART_NR

#define AMBA_ISR_PASS_LIMIT	256

#define UART_DR_ERROR		(UART011_DR_OE|UART011_DR_BE|UART011_DR_PE|UART011_DR_FE)
#define UART_DUMMY_DR_RX	(1 << 16)

/*
 * We wrap our port structure around the generic uart_port.
 */
struct uart_amba_port {
	struct uart_port	port;
	struct clk		*clk;
	unsigned int		im;	/* interrupt mask */
	unsigned int		old_status;
};

static void pl011_stop_tx(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;

	uap->im &= ~UART011_TXIM;
	writew(uap->im, uap->port.membase + UART011_IMSC);
}

static void pl011_start_tx(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;

	uap->im |= UART011_TXIM;
	writew(uap->im, uap->port.membase + UART011_IMSC);
}

static void pl011_stop_rx(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;

	uap->im &= ~(UART011_RXIM|UART011_RTIM|UART011_FEIM|
		     UART011_PEIM|UART011_BEIM|UART011_OEIM);
	writew(uap->im, uap->port.membase + UART011_IMSC);
}

static void pl011_enable_ms(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;

	uap->im |= UART011_RIMIM|UART011_CTSMIM|UART011_DCDMIM|UART011_DSRMIM;
	writew(uap->im, uap->port.membase + UART011_IMSC);
}

static void pl011_rx_chars(struct uart_amba_port *uap)
{
	struct tty_struct *tty = uap->port.info->port.tty;
	unsigned int status, ch, flag, max_count = 256;

	status = readw(uap->port.membase + UART01x_FR);
	while ((status & UART01x_FR_RXFE) == 0 && max_count--) {
		ch = readw(uap->port.membase + UART01x_DR) | UART_DUMMY_DR_RX;
		flag = TTY_NORMAL;
		uap->port.icount.rx++;

		/*
		 * Note that the error handling code is
		 * out of the main execution path
		 */
		if (unlikely(ch & UART_DR_ERROR)) {
			if (ch & UART011_DR_BE) {
				ch &= ~(UART011_DR_FE | UART011_DR_PE);
				uap->port.icount.brk++;
				if (uart_handle_break(&uap->port))
					goto ignore_char;
			} else if (ch & UART011_DR_PE)
				uap->port.icount.parity++;
			else if (ch & UART011_DR_FE)
				uap->port.icount.frame++;
			if (ch & UART011_DR_OE)
				uap->port.icount.overrun++;

			ch &= uap->port.read_status_mask;

			if (ch & UART011_DR_BE)
				flag = TTY_BREAK;
			else if (ch & UART011_DR_PE)
				flag = TTY_PARITY;
			else if (ch & UART011_DR_FE)
				flag = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(&uap->port, ch & 255))
			goto ignore_char;

		uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag);

	ignore_char:
		status = readw(uap->port.membase + UART01x_FR);
	}
	spin_unlock(&uap->port.lock);
	tty_flip_buffer_push(tty);
	spin_lock(&uap->port.lock);
}

static void pl011_tx_chars(struct uart_amba_port *uap)
{
	struct circ_buf *xmit = &uap->port.info->xmit;
	int count;

	if (uap->port.x_char) {
		writew(uap->port.x_char, uap->port.membase + UART01x_DR);
		uap->port.icount.tx++;
		uap->port.x_char = 0;
		return;
	}
	if (uart_circ_empty(xmit) || uart_tx_stopped(&uap->port)) {