path: root/drivers/serial/amba-pl011.c

/*
 *  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 <linux/slab.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;
	unsigned int		ifls;		/* vendor-specific */
	unsigned int		lcrh_tx;	/* vendor-specific */
	unsigned int		lcrh_rx;	/* vendor-specific */
	bool			oversampling;   /* vendor-specific */
	bool			autorts;
};

/* There is by now at least one vendor with differing details, so handle it */
struct vendor_data {
	unsigned int		ifls;
	unsigned int		fifosize;
	unsigned int		lcrh_tx;
	unsigned int		lcrh_rx;
	bool			oversampling;
};

static struct vendor_data vendor_arm = {
	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
	.fifosize		= 16,
	.lcrh_tx		= UART011_LCRH,
	.lcrh_rx		= UART011_LCRH,
	.oversampling		= false,
};

static struct vendor_data vendor_st = {
	.ifls			= UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
	.fifosize		= 64,
	.lcrh_tx		= ST_UART011_LCRH_TX,
	.lcrh_rx		= ST_UART011_LCRH_RX,
	.oversampling		= true,
};

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.state->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.icou