au1x00_uart.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,391 行 · 第 1/3 页

/*
 *  Driver for 8250/16550-type serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright (C) 2001 Russell King.
 *
 * 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.
 *
 * A note about mapbase / membase
 *
 *  mapbase is the physical address of the IO port.  Currently, we don't
 *  support this very well, and it may well be dropped from this driver
 *  in future.  As such, mapbase should be NULL.
 *
 *  membase is an 'ioremapped' cookie.  This is compatible with the old
 *  serial.c driver, and is currently the preferred form.
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/delay.h>

#include <asm/serial.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/mach-au1x00/au1000.h>

#if defined(CONFIG_SERIAL_AU1X00_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>
#include "8250.h"

/*
 * Debugging.
 */
#if 0
#define DEBUG_AUTOCONF(fmt...)	printk(fmt)
#else
#define DEBUG_AUTOCONF(fmt...)	do { } while (0)
#endif

#if 0
#define DEBUG_INTR(fmt...)	printk(fmt)
#else
#define DEBUG_INTR(fmt...)	do { } while (0)
#endif

#define PASS_LIMIT	256

/*
 * We default to IRQ0 for the "no irq" hack.   Some
 * machine types want others as well - they're free
 * to redefine this in their header file.
 */
#define is_real_interrupt(irq)	((irq) != 0)

static struct old_serial_port old_serial_port[] = {
	{	.baud_base = 0,
		.iomem_base = (u8 *)UART0_ADDR,
		.irq = AU1000_UART0_INT,
		.flags = STD_COM_FLAGS,
		.iomem_reg_shift = 2,
	}, {
		.baud_base = 0,
		.iomem_base = (u8 *)UART1_ADDR,
		.irq = AU1000_UART1_INT,
		.flags = STD_COM_FLAGS,
		.iomem_reg_shift = 2
	}, {
		.baud_base = 0,
		.iomem_base = (u8 *)UART2_ADDR,
		.irq = AU1000_UART2_INT,
		.flags = STD_COM_FLAGS,
		.iomem_reg_shift = 2
	}, {
		.baud_base = 0,
		.iomem_base = (u8 *)UART3_ADDR,
		.irq = AU1000_UART3_INT,
		.flags = STD_COM_FLAGS,
		.iomem_reg_shift = 2
	}
};

#define UART_NR	ARRAY_SIZE(old_serial_port)

struct uart_8250_port {
	struct uart_port	port;
	struct timer_list	timer;		/* "no irq" timer */
	struct list_head	list;		/* ports on this IRQ */
	unsigned short		rev;
	unsigned char		acr;
	unsigned char		ier;
	unsigned char		lcr;
	unsigned char		mcr_mask;	/* mask of user bits */
	unsigned char		mcr_force;	/* mask of forced bits */
	unsigned char		lsr_break_flag;

	/*
	 * We provide a per-port pm hook.
	 */
	void			(*pm)(struct uart_port *port,
				      unsigned int state, unsigned int old);
};

struct irq_info {
	spinlock_t		lock;
	struct list_head	*head;
};

static struct irq_info irq_lists[NR_IRQS];

/*
 * Here we define the default xmit fifo size used for each type of UART.
 */
static const struct serial_uart_config uart_config[PORT_MAX_8250+1] = {
	{ "unknown",	1,	0 },
	{ "8250",	1,	0 },
	{ "16450",	1,	0 },
	{ "16550",	1,	0 },
	/* PORT_16550A */
	{ "AU1X00_UART",16,	UART_CLEAR_FIFO | UART_USE_FIFO },
};

static _INLINE_ unsigned int serial_in(struct uart_8250_port *up, int offset)
{
	return au_readl((unsigned long)up->port.membase + offset);
}

static _INLINE_ void
serial_out(struct uart_8250_port *up, int offset, int value)
{
	au_writel(value, (unsigned long)up->port.membase + offset);
}

#define serial_inp(up, offset)		serial_in(up, offset)
#define serial_outp(up, offset, value)	serial_out(up, offset, value)

/*
 * This routine is called by rs_init() to initialize a specific serial
 * port.  It determines what type of UART chip this serial port is
 * using: 8250, 16450, 16550, 16550A.  The important question is
 * whether or not this UART is a 16550A or not, since this will
 * determine whether or not we can use its FIFO features or not.
 */
static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
{
	unsigned char save_lcr, save_mcr;
	unsigned long flags;

	if (!up->port.iobase && !up->port.mapbase && !up->port.membase)
		return;

	DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04x, 0x%08lx): ",
			up->port.line, up->port.iobase, up->port.membase);

	/*
	 * We really do need global IRQs disabled here - we're going to
	 * be frobbing the chips IRQ enable register to see if it exists.
	 */
	spin_lock_irqsave(&up->port.lock, flags);
//	save_flags(flags); cli();

	save_mcr = serial_in(up, UART_MCR);
	save_lcr = serial_in(up, UART_LCR);

	up->port.type = PORT_16550A;
	serial_outp(up, UART_LCR, save_lcr);

	up->port.fifosize = uart_config[up->port.type].dfl_xmit_fifo_size;

	if (up->port.type == PORT_UNKNOWN)
		goto out;

	/*
	 * Reset the UART.
	 */
	serial_outp(up, UART_MCR, save_mcr);
	serial_outp(up, UART_FCR, (UART_FCR_ENABLE_FIFO |
				     UART_FCR_CLEAR_RCVR |
				     UART_FCR_CLEAR_XMIT));
	serial_outp(up, UART_FCR, 0);
	(void)serial_in(up, UART_RX);
	serial_outp(up, UART_IER, 0);

 out:	
	spin_unlock_irqrestore(&up->port.lock, flags);
//	restore_flags(flags);
	DEBUG_AUTOCONF("type=%s\n", uart_config[up->port.type].name);
}

static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
{
	struct uart_8250_port *up = (struct uart_8250_port *)port;

	if (up->ier & UART_IER_THRI) {
		up->ier &= ~UART_IER_THRI;
		serial_out(up, UART_IER, up->ier);
	}
}

static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
{
	struct uart_8250_port *up = (struct uart_8250_port *)port;

	if (!(up->ier & UART_IER_THRI)) {
		up->ier |= UART_IER_THRI;
		serial_out(up, UART_IER, up->ier);
	}
}

static void serial8250_stop_rx(struct uart_port *port)
{
	struct uart_8250_port *up = (struct uart_8250_port *)port;

	up->ier &= ~UART_IER_RLSI;
	up->port.read_status_mask &= ~UART_LSR_DR;
	serial_out(up, UART_IER, up->ier);
}

static void serial8250_enable_ms(struct uart_port *port)
{
	struct uart_8250_port *up = (struct uart_8250_port *)port;

	up->ier |= UART_IER_MSI;
	serial_out(up, UART_IER, up->ier);
}

static _INLINE_ void
receive_chars(struct uart_8250_port *up, int *status, struct pt_regs *regs)
{
	struct tty_struct *tty = up->port.info->tty;
	unsigned char ch;
	int max_count = 256;

	do {
		if (unlikely(tty->flip.count >= TTY_FLIPBUF_SIZE)) {
			tty->flip.work.func((void *)tty);
			if (tty->flip.count >= TTY_FLIPBUF_SIZE)
				return; // if TTY_DONT_FLIP is set
		}
		ch = serial_inp(up, UART_RX);
		*tty->flip.char_buf_ptr = ch;
		*tty->flip.flag_buf_ptr = TTY_NORMAL;
		up->port.icount.rx++;

		if (unlikely(*status & (UART_LSR_BI | UART_LSR_PE |
				       UART_LSR_FE | UART_LSR_OE))) {
			/*
			 * For statistics only
			 */
			if (*status & UART_LSR_BI) {
				*status &= ~(UART_LSR_FE | UART_LSR_PE);
				up->port.icount.brk++;
				/*
				 * We do the SysRQ and SAK checking
				 * here because otherwise the break
				 * may get masked by ignore_status_mask
				 * or read_status_mask.
				 */
				if (uart_handle_break(&up->port))
					goto ignore_char;
			} else if (*status & UART_LSR_PE)
				up->port.icount.parity++;
			else if (*status & UART_LSR_FE)
				up->port.icount.frame++;
			if (*status & UART_LSR_OE)
				up->port.icount.overrun++;

			/*
			 * Mask off conditions which should be ingored.
			 */
			*status &= up->port.read_status_mask;

#ifdef CONFIG_SERIAL_AU1X00_CONSOLE
			if (up->port.line == up->port.cons->index) {
				/* Recover the break flag from console xmit */
				*status |= up->lsr_break_flag;
				up->lsr_break_flag = 0;
			}
#endif
			if (*status & UART_LSR_BI) {
				DEBUG_INTR("handling break....");
				*tty->flip.flag_buf_ptr = TTY_BREAK;
			} else if (*status & UART_LSR_PE)
				*tty->flip.flag_buf_ptr = TTY_PARITY;
			else if (*status & UART_LSR_FE)
				*tty->flip.flag_buf_ptr = TTY_FRAME;
		}
		if (uart_handle_sysrq_char(&up->port, ch, regs))
			goto ignore_char;
		if ((*status & up->port.ignore_status_mask) == 0) {
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}
		if ((*status & UART_LSR_OE) &&
		    tty->flip.count < TTY_FLIPBUF_SIZE) {
			/*
			 * Overrun is special, since it's reported
			 * immediately, and doesn't affect the current
			 * character.
			 */
			*tty->flip.flag_buf_ptr = TTY_OVERRUN;
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}
	ignore_char:
		*status = serial_inp(up, UART_LSR);
	} while ((*status & UART_LSR_DR) && (max_count-- > 0));
	tty_flip_buffer_push(tty);
}

static _INLINE_ void transmit_chars(struct uart_8250_port *up)
{
	struct circ_buf *xmit = &up->port.info->xmit;
	int count;

	if (up->port.x_char) {
		serial_outp(up, UART_TX, up->port.x_char);
		up->port.icount.tx++;
		up->port.x_char = 0;
		return;
	}
	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
		serial8250_stop_tx(&up->port, 0);
		return;
	}

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

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

	DEBUG_INTR("THRE...");

	if (uart_circ_empty(xmit))
		serial8250_stop_tx(&up->port, 0);
}

static _INLINE_ void check_modem_status(struct uart_8250_port *up)
{
	int status;

	status = serial_in(up, UART_MSR);

	if ((status & UART_MSR_ANY_DELTA) == 0)
		return;

	if (status & UART_MSR_TERI)
		up->port.icount.rng++;
	if (status & UART_MSR_DDSR)
		up->port.icount.dsr++;
	if (status & UART_MSR_DDCD)
		uart_handle_dcd_change(&up->port, status & UART_MSR_DCD);
	if (status & UART_MSR_DCTS)
		uart_handle_cts_change(&up->port, status & UART_MSR_CTS);

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

/*
 * This handles the interrupt from one port.
 */
static inline void
serial8250_handle_port(struct uart_8250_port *up, struct pt_regs *regs)
{
	unsigned int status = serial_inp(up, UART_LSR);

	DEBUG_INTR("status = %x...", status);

	if (status & UART_LSR_DR)
		receive_chars(up, &status, regs);
	check_modem_status(up);
	if (status & UART_LSR_THRE)
		transmit_chars(up);
}

/*
 * This is the serial driver's interrupt routine.
 *
 * Arjan thinks the old way was overly complex, so it got simplified.
 * Alan disagrees, saying that need the complexity to handle the weird
 * nature of ISA shared interrupts.  (This is a special exception.)
 *
 * In order to handle ISA shared interrupts properly, we need to check
 * that all ports have been serviced, and therefore the ISA interrupt
 * line has been de-asserted.
 *
 * This means we need to loop through all ports. checking that they
 * don't have an interrupt pending.
 */
static irqreturn_t serial8250_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct irq_info *i = dev_id;
	struct list_head *l, *end = NULL;
	int pass_counter = 0;

	DEBUG_INTR("serial8250_interrupt(%d)...", irq);

	spin_lock(&i->lock);

	l = i->head;
	do {
		struct uart_8250_port *up;
		unsigned int iir;

		up = list_entry(l, struct uart_8250_port, list);

		iir = serial_in(up, UART_IIR);
		if (!(iir & UART_IIR_NO_INT)) {
			spin_lock(&up->port.lock);
			serial8250_handle_port(up, regs);
			spin_unlock(&up->port.lock);

			end = NULL;
		} else if (end == NULL)
			end = l;

		l = l->next;

		if (l == i->head && pass_counter++ > PASS_LIMIT) {
			/* If we hit this, we're dead. */
			printk(KERN_ERR "serial8250: too much work for "
				"irq%d\n", irq);
			break;
		}
	} while (l != end);

	spin_unlock(&i->lock);

	DEBUG_INTR("end.\n");
	/* FIXME! Was it really ours? */
	return IRQ_HANDLED;
}

/*
 * To support ISA shared interrupts, we need to have one interrupt
 * handler that ensures that the IRQ line has been deasserted
 * before returning.  Failing to do this will result in the IRQ
 * line being stuck active, and, since ISA irqs are edge triggered,
 * no more IRQs will be seen.
 */
static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
{