amba-pl011.c

Linux Kernel 2.6.9 for OMAP1710

/*
 *  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
 *
 *  $Id: amba.c,v 1.41 2002/07/28 10:03:27 rmk Exp $
 *
 * 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.
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/device.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/hardware/amba.h>
#include <asm/hardware/clock.h>

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

#include <linux/serial_core.h>

#include <asm/hardware/amba_serial.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_DUMMY_RSR_RX	256

/*
 * 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, unsigned int tty_stop)
{
	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, unsigned int tty_start)
{
	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
#ifdef SUPPORT_SYSRQ
pl011_rx_chars(struct uart_amba_port *uap, struct pt_regs *regs)
#else
pl011_rx_chars(struct uart_amba_port *uap)
#endif
{
	struct tty_struct *tty = uap->port.info->tty;
	unsigned int status, ch, rsr, max_count = 256;

	status = readw(uap->port.membase + UART01x_FR);
	while ((status & UART01x_FR_RXFE) == 0 && max_count--) {
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			tty->flip.work.func((void *)tty);
			if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
				printk(KERN_WARNING "TTY_DONT_FLIP set\n");
				return;
			}
		}

		ch = readw(uap->port.membase + UART01x_DR);

		*tty->flip.char_buf_ptr = ch;
		*tty->flip.flag_buf_ptr = TTY_NORMAL;
		uap->port.icount.rx++;

		/*
		 * Note that the error handling code is
		 * out of the main execution path
		 */
		rsr = readw(uap->port.membase + UART01x_RSR) | UART_DUMMY_RSR_RX;
		if (rsr & UART01x_RSR_ANY) {
			if (rsr & UART01x_RSR_BE) {
				rsr &= ~(UART01x_RSR_FE | UART01x_RSR_PE);
				uap->port.icount.brk++;
				if (uart_handle_break(&uap->port))
					goto ignore_char;
			} else if (rsr & UART01x_RSR_PE)
				uap->port.icount.parity++;
			else if (rsr & UART01x_RSR_FE)
				uap->port.icount.frame++;
			if (rsr & UART01x_RSR_OE)
				uap->port.icount.overrun++;

			rsr &= uap->port.read_status_mask;

			if (rsr & UART01x_RSR_BE)
				*tty->flip.flag_buf_ptr = TTY_BREAK;
			else if (rsr & UART01x_RSR_PE)
				*tty->flip.flag_buf_ptr = TTY_PARITY;
			else if (rsr & UART01x_RSR_FE)
				*tty->flip.flag_buf_ptr = TTY_FRAME;
		}

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

		if ((rsr & uap->port.ignore_status_mask) == 0) {
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}
		if ((rsr & UART01x_RSR_OE) &&
		    tty->flip.count < TTY_FLIPBUF_SIZE) {
			/*
			 * Overrun is special, since it's reported
			 * immediately, and doesn't affect the current
			 * character
			 */
			*tty->flip.char_buf_ptr++ = 0;
			*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
			tty->flip.count++;
		}
	ignore_char:
		status = readw(uap->port.membase + UART01x_FR);
	}
	tty_flip_buffer_push(tty);
	return;
}

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)) {
		pl011_stop_tx(&uap->port, 0);
		return;
	}

	count = uap->port.fifosize >> 1;
	do {
		writew(xmit->buf[xmit->tail], uap->port.membase + UART01x_DR);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		uap->port.icount.tx++;
		if (uart_circ_empty(xmit))
			break;
	} while (--count > 0);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&uap->port);

	if (uart_circ_empty(xmit))
		pl011_stop_tx(&uap->port, 0);
}

static void pl011_modem_status(struct uart_amba_port *uap)
{
	unsigned int status, delta;

	status = readw(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;

	delta = status ^ uap->old_status;
	uap->old_status = status;

	if (!delta)
		return;

	if (delta & UART01x_FR_DCD)
		uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);

	if (delta & UART01x_FR_DSR)
		uap->port.icount.dsr++;

	if (delta & UART01x_FR_CTS)
		uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);

	wake_up_interruptible(&uap->port.info->delta_msr_wait);
}

static irqreturn_t pl011_int(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_amba_port *uap = dev_id;
	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
	int handled = 0;

	spin_lock(&uap->port.lock);

	status = readw(uap->port.membase + UART011_MIS);
	if (status) {
		do {
			writew(status & ~(UART011_TXIS|UART011_RTIS|
					  UART011_RXIS),
			       uap->port.membase + UART011_ICR);

			if (status & (UART011_RTIS|UART011_RXIS))
#ifdef SUPPORT_SYSRQ
				pl011_rx_chars(uap, regs);
#else
				pl011_rx_chars(uap);
#endif
			if (status & (UART011_DSRMIS|UART011_DCDMIS|
				      UART011_CTSMIS|UART011_RIMIS))
				pl011_modem_status(uap);
			if (status & UART011_TXIS)
				pl011_tx_chars(uap);

			if (pass_counter-- == 0)
				break;

			status = readw(uap->port.membase + UART011_MIS);
		} while (status != 0);
		handled = 1;
	}

	spin_unlock(&uap->port.lock);

	return IRQ_RETVAL(handled);
}

static unsigned int pl01x_tx_empty(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;
	unsigned int status = readw(uap->port.membase + UART01x_FR);
	return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
}

static unsigned int pl01x_get_mctrl(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;
	unsigned int result = 0;
	unsigned int status = readw(uap->port.membase + UART01x_FR);

#define BIT(uartbit, tiocmbit)		\
	if (status & uartbit)		\
		result |= tiocmbit

	BIT(UART01x_FR_DCD, TIOCM_CAR);
	BIT(UART01x_FR_DSR, TIOCM_DSR);
	BIT(UART01x_FR_CTS, TIOCM_CTS);
	BIT(UART011_FR_RI, TIOCM_RNG);
#undef BIT
	return result;
}

static void pl011_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;
	unsigned int cr;

	cr = readw(uap->port.membase + UART011_CR);

#define	BIT(tiocmbit, uartbit)		\
	if (mctrl & tiocmbit)		\
		cr |= uartbit;		\
	else				\
		cr &= ~uartbit

	BIT(TIOCM_RTS, UART011_CR_RTS);
	BIT(TIOCM_DTR, UART011_CR_DTR);
	BIT(TIOCM_OUT1, UART011_CR_OUT1);
	BIT(TIOCM_OUT2, UART011_CR_OUT2);
	BIT(TIOCM_LOOP, UART011_CR_LBE);
#undef BIT

	writew(cr, uap->port.membase + UART011_CR);
}

static void pl011_break_ctl(struct uart_port *port, int break_state)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;
	unsigned long flags;
	unsigned int lcr_h;

	spin_lock_irqsave(&uap->port.lock, flags);
	lcr_h = readw(uap->port.membase + UART011_LCRH);
	if (break_state == -1)
		lcr_h |= UART01x_LCRH_BRK;
	else
		lcr_h &= ~UART01x_LCRH_BRK;
	writew(lcr_h, uap->port.membase + UART011_LCRH);
	spin_unlock_irqrestore(&uap->port.lock, flags);
}

static int pl011_startup(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;
	unsigned int cr;
	int retval;

	/*
	 * Try to enable the clock producer.
	 */
	retval = clk_enable(uap->clk);
	if (retval)
		goto out;

	uap->port.uartclk = clk_get_rate(uap->clk);

	/*
	 * Allocate the IRQ
	 */
	retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
	if (retval)
		goto clk_dis;

	writew(UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
	       uap->port.membase + UART011_IFLS);

	/*
	 * Provoke TX FIFO interrupt into asserting.
	 */
	cr = UART01x_CR_UARTEN | UART011_CR_TXE | UART011_CR_LBE;
	writew(cr, uap->port.membase + UART011_CR);
	writew(0, uap->port.membase + UART011_FBRD);
	writew(1, uap->port.membase + UART011_IBRD);
	writew(0, uap->port.membase + UART011_LCRH);
	writew(0, uap->port.membase + UART01x_DR);
	while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_BUSY)
		barrier();

	cr = UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;
	writew(cr, uap->port.membase + UART011_CR);

	/*
	 * initialise the old status of the modem signals
	 */
	uap->old_status = readw(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;

	/*
	 * Finally, enable interrupts
	 */
	spin_lock_irq(&uap->port.lock);
	uap->im = UART011_RXIM | UART011_RTIM;
	writew(uap->im, uap->port.membase + UART011_IMSC);
	spin_unlock_irq(&uap->port.lock);

	return 0;

 clk_dis:
	clk_disable(uap->clk);
 out:
	return retval;
}

static void pl011_shutdown(struct uart_port *port)
{
	struct uart_amba_port *uap = (struct uart_amba_port *)port;
	unsigned long val;

	/*
	 * disable all interrupts
	 */
	spin_lock_irq(&uap->port.lock);
	uap->im = 0;
	writew(uap->im, uap->port.membase + UART011_IMSC);
	writew(0xffff, uap->port.membase + UART011_ICR);
	spin_unlock_irq(&uap->port.lock);

	/*
	 * Free the interrupt
	 */
	free_irq(uap->port.irq, uap);

	/*
	 * disable the port
	 */
	writew(UART01x_CR_UARTEN | UART011_CR_TXE, uap->port.membase + UART011_CR);

	/*
	 * disable break condition and fifos
	 */
	val = readw(uap->port.membase + UART011_LCRH);