8250.c

linux 2.6内核下8250串口设备驱动程序

	if (ret < 0)
		probeflags &= ~PROBE_RSA;

	if (flags & UART_CONFIG_TYPE)
		autoconfig(up, probeflags);
	if (up->port.type != PORT_UNKNOWN && flags & UART_CONFIG_IRQ)
		autoconfig_irq(up);

	if (up->port.type != PORT_RSA && probeflags & PROBE_RSA)
		serial8250_release_rsa_resource(up);
	if (up->port.type == PORT_UNKNOWN)
		serial8250_release_std_resource(up);
}

static int
serial8250_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	if (ser->irq >= NR_IRQS || ser->irq < 0 ||
	    ser->baud_base < 9600 || ser->type < PORT_UNKNOWN ||
	    ser->type >= ARRAY_SIZE(uart_config) || ser->type == PORT_CIRRUS ||
	    ser->type == PORT_STARTECH)
		return -EINVAL;
	return 0;
}

static const char *
serial8250_type(struct uart_port *port)
{
	int type = port->type;

	if (type >= ARRAY_SIZE(uart_config))
		type = 0;
	return uart_config[type].name;
}

static struct uart_ops serial8250_pops = {
	.tx_empty	= serial8250_tx_empty,
	.set_mctrl	= serial8250_set_mctrl,
	.get_mctrl	= serial8250_get_mctrl,
	.stop_tx	= serial8250_stop_tx,
	.start_tx	= serial8250_start_tx,
	.stop_rx	= serial8250_stop_rx,
	.enable_ms	= serial8250_enable_ms,
	.break_ctl	= serial8250_break_ctl,
	.startup	= serial8250_startup,
	.shutdown	= serial8250_shutdown,
	.set_termios	= serial8250_set_termios,
	.pm		= serial8250_pm,
	.type		= serial8250_type,
	.release_port	= serial8250_release_port,
	.request_port	= serial8250_request_port,
	.config_port	= serial8250_config_port,
	.verify_port	= serial8250_verify_port,
};

static struct uart_8250_port serial8250_ports[UART_NR];

static void __init serial8250_isa_init_ports(void)
{
	struct uart_8250_port *up;
	static int first = 1;
	int i;

	if (!first)
		return;
	first = 0;

	for (i = 0; i < nr_uarts; i++) {
		struct uart_8250_port *up = &serial8250_ports[i];

		up->port.line = i;
		spin_lock_init(&up->port.lock);

		init_timer(&up->timer);
		up->timer.function = serial8250_timeout;

		/*
		 * ALPHA_KLUDGE_MCR needs to be killed.
		 */
		up->mcr_mask = ~ALPHA_KLUDGE_MCR;
		up->mcr_force = ALPHA_KLUDGE_MCR;

		up->port.ops = &serial8250_pops;
	}

	for (i = 0, up = serial8250_ports;
	     i < ARRAY_SIZE(old_serial_port) && i < nr_uarts;
	     i++, up++) {
		up->port.iobase   = old_serial_port[i].port;
		up->port.irq      = irq_canonicalize(old_serial_port[i].irq);
		up->port.uartclk  = old_serial_port[i].baud_base * 16;
		up->port.flags    = old_serial_port[i].flags;
		up->port.hub6     = old_serial_port[i].hub6;
		up->port.membase  = old_serial_port[i].iomem_base;
		up->port.iotype   = old_serial_port[i].io_type;
		up->port.regshift = old_serial_port[i].iomem_reg_shift;
		if (share_irqs)
			up->port.flags |= UPF_SHARE_IRQ;
	}
}

static void __init
serial8250_register_ports(struct uart_driver *drv, struct device *dev)
{
	int i;

	serial8250_isa_init_ports();

	for (i = 0; i < nr_uarts; i++) {
		struct uart_8250_port *up = &serial8250_ports[i];

		up->port.dev = dev;
		uart_add_one_port(drv, &up->port);
	}
}

#ifdef CONFIG_SERIAL_8250_CONSOLE

#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)

/*
 *	Wait for transmitter & holding register to empty
 */
static inline void wait_for_xmitr(struct uart_8250_port *up, int bits)
{
	unsigned int status, tmout = 10000;

	/* Wait up to 10ms for the character(s) to be sent. */
	do {
		status = serial_in(up, UART_LSR);

		if (status & UART_LSR_BI)
			up->lsr_break_flag = UART_LSR_BI;

		if (--tmout == 0)
			break;
		udelay(1);
	} while ((status & bits) != bits);

	/* Wait up to 1s for flow control if necessary */
	if (up->port.flags & UPF_CONS_FLOW) {
		tmout = 1000000;
		while (!(serial_in(up, UART_MSR) & UART_MSR_CTS) && --tmout) {
			udelay(1);
			touch_nmi_watchdog();
		}
	}
}

static void serial8250_console_putchar(struct uart_port *port, int ch)
{
	struct uart_8250_port *up = (struct uart_8250_port *)port;

	wait_for_xmitr(up, UART_LSR_THRE);
	serial_out(up, UART_TX, ch);
}

/*
 *	Print a string to the serial port trying not to disturb
 *	any possible real use of the port...
 *
 *	The console_lock must be held when we get here.
 */
static void
serial8250_console_write(struct console *co, const char *s, unsigned int count)
{
	struct uart_8250_port *up = &serial8250_ports[co->index];
	unsigned long flags;
	unsigned int ier;
	int locked = 1;

	touch_nmi_watchdog();

	local_irq_save(flags);
	if (up->port.sysrq) {
		/* serial8250_handle_port() already took the lock */
		locked = 0;
	} else if (oops_in_progress) {
		locked = spin_trylock(&up->port.lock);
	} else
		spin_lock(&up->port.lock);

	/*
	 *	First save the IER then disable the interrupts
	 */
	ier = serial_in(up, UART_IER);

	if (up->capabilities & UART_CAP_UUE)
		serial_out(up, UART_IER, UART_IER_UUE);
	else
		serial_out(up, UART_IER, 0);

	uart_console_write(&up->port, s, count, serial8250_console_putchar);

	/*
	 *	Finally, wait for transmitter to become empty
	 *	and restore the IER
	 */
	wait_for_xmitr(up, BOTH_EMPTY);
	serial_out(up, UART_IER, ier);

	if (locked)
		spin_unlock(&up->port.lock);
	local_irq_restore(flags);
}

static int __init serial8250_console_setup(struct console *co, char *options)
{
	struct uart_port *port;
	int baud = 9600;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	/*
	 * Check whether an invalid uart number has been specified, and
	 * if so, search for the first available port that does have
	 * console support.
	 */
	if (co->index >= nr_uarts)
		co->index = 0;
	port = &serial8250_ports[co->index].port;
	if (!port->iobase && !port->membase)
		return -ENODEV;

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct uart_driver serial8250_reg;
static struct console serial8250_console = {
	.name		= "ttyS",
	.write		= serial8250_console_write,
	.device		= uart_console_device,
	.setup		= serial8250_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &serial8250_reg,
};

static int __init serial8250_console_init(void)
{
	serial8250_isa_init_ports();
	register_console(&serial8250_console);
	return 0;
}
console_initcall(serial8250_console_init);

static int __init find_port(struct uart_port *p)
{
	int line;
	struct uart_port *port;

	for (line = 0; line < nr_uarts; line++) {
		port = &serial8250_ports[line].port;
		if (uart_match_port(p, port))
			return line;
	}
	return -ENODEV;
}

int __init serial8250_start_console(struct uart_port *port, char *options)
{
	int line;

	line = find_port(port);
	if (line < 0)
		return -ENODEV;

	add_preferred_console("ttyS", line, options);
	printk("Adding console on ttyS%d at %s 0x%lx (options '%s')\n",
		line, port->iotype == UPIO_MEM ? "MMIO" : "I/O port",
		port->iotype == UPIO_MEM ? (unsigned long) port->mapbase :
		    (unsigned long) port->iobase, options);
	if (!(serial8250_console.flags & CON_ENABLED)) {
		serial8250_console.flags &= ~CON_PRINTBUFFER;
		register_console(&serial8250_console);
	}
	return line;
}

#define SERIAL8250_CONSOLE	&serial8250_console
#else
#define SERIAL8250_CONSOLE	NULL
#endif

static struct uart_driver serial8250_reg = {
	.owner			= THIS_MODULE,
	.driver_name		= "serial",
	.dev_name		= "ttyS",
	.major			= TTY_MAJOR,
	.minor			= 64,
	.nr			= UART_NR,
	.cons			= SERIAL8250_CONSOLE,
};

/*
 * early_serial_setup - early registration for 8250 ports
 *
 * Setup an 8250 port structure prior to console initialisation.  Use
 * after console initialisation will cause undefined behaviour.
 */
int __init early_serial_setup(struct uart_port *port)
{
	if (port->line >= ARRAY_SIZE(serial8250_ports))
		return -ENODEV;

	serial8250_isa_init_ports();
	serial8250_ports[port->line].port	= *port;
	serial8250_ports[port->line].port.ops	= &serial8250_pops;
	return 0;
}

/**
 *	serial8250_suspend_port - suspend one serial port
 *	@line:  serial line number
 *
 *	Suspend one serial port.
 */
void serial8250_suspend_port(int line)
{
	uart_suspend_port(&serial8250_reg, &serial8250_ports[line].port);
}

/**
 *	serial8250_resume_port - resume one serial port
 *	@line:  serial line number
 *
 *	Resume one serial port.
 */
void serial8250_resume_port(int line)
{
	uart_resume_port(&serial8250_reg, &serial8250_ports[line].port);
}

/*
 * Register a set of serial devices attached to a platform device.  The
 * list is terminated with a zero flags entry, which means we expect
 * all entries to have at least UPF_BOOT_AUTOCONF set.
 */
static int __devinit serial8250_probe(struct platform_device *dev)
{
	struct plat_serial8250_port *p = dev->dev.platform_data;
	struct uart_port port;
	int ret, i;

	memset(&port, 0, sizeof(struct uart_port));

	for (i = 0; p && p->flags != 0; p++, i++) {
		port.iobase	= p->iobase;
		port.membase	= p->membase;
		port.irq	= p->irq;
		port.uartclk	= p->uartclk;
		port.regshift	= p->regshift;
		port.iotype	= p->iotype;
		port.flags	= p->flags;
		port.mapbase	= p->mapbase;
		port.hub6	= p->hub6;
		port.dev	= &dev->dev;
		if (share_irqs)
			port.flags |= UPF_SHARE_IRQ;
		ret = serial8250_register_port(&port);
		if (ret < 0) {
			dev_err(&dev->dev, "unable to register port at index %d "
				"(IO%lx MEM%lx IRQ%d): %d\n", i,
				p->iobase, p->mapbase, p->irq, ret);
		}
	}
	return 0;
}

/*
 * Remove serial ports registered against a platform device.
 */
static int __devexit serial8250_remove(struct platform_device *dev)
{
	int i;

	for (i = 0; i < nr_uarts; i++) {
		struct uart_8250_port *up = &serial8250_ports[i];

		if (up->port.dev == &dev->dev)
			serial8250_unregister_port(i);
	}
	return 0;
}

static int serial8250_suspend(struct platform_device *dev, pm_message_t state)
{
	int i;

	for (i = 0; i < UART_NR; i++) {
		struct uart_8250_port *up = &serial8250_ports[i];

		if (up->port.type != PORT_UNKNOWN && up->port.dev == &dev->dev)
			uart_suspend_port(&serial8250_reg, &up->port);
	}

	return 0;
}

static int serial8250_resume(struct platform_device *dev)
{
	int i;

	for (i = 0; i < UART_NR; i++) {
		struct uart_8250_port *up = &serial8250_ports[i];

		if (up->port.type != PORT_UNKNOWN && up->port.dev == &dev->dev)
			uart_resume_port(&serial8250_reg, &up->port);
	}

	return 0;
}

static struct platform_driver serial8250_isa_driver = {
	.probe		= serial8250_probe,
	.remove		= __devexit_p(serial8250_remove),
	.suspend	= serial8250_suspend,
	.resume		= serial8250_resume,
	.driver		= {
		.name	= "serial8250",
		.owner	= THIS_MODULE,
	},
};

/*
 * This "device" covers _all_ ISA 8250-compatible serial devices listed
 * in the table in include/asm/serial.h
 */
static struct platform_device *serial8250_isa_devs;

/*
 * serial8250_register_port and serial8250_unregister_port allows for
 * 16x50 serial ports to be configured at run-time, to support PCMCIA
 * modems and PCI multiport cards.
 */
static DEFINE_MUTEX(serial_mutex);

static struct uart_8250_port *serial8250_find_match_or_unused(struct uart_port *port)
{
	int i;

	/*
	 * First, find a port entry which matches.
	 */
	for (i = 0; i < nr_uarts; i++)
		if (uart_match_port(&serial8250_ports[i].port, port))
			return &serial8250_ports[i];

	/*
	 * We didn't find a matching entry, so look for the first
	 * free entry.  We look for one which hasn't been previously
	 * used (indicated by zero iobase).
	 */
	for (i = 0; i < nr_uarts; i++)
		if (serial8250_ports[i].port.type == PORT_UNKNOWN &&
		    serial8250_ports[i].port.iobase == 0)
			return &serial8250_ports[i];

	/*
	 * That also failed.  Last resort is to find any entry which
	 * doesn't have a real port associated with it.
	 */
	for (i = 0; i < nr_uarts; i++)
		if (serial8250_ports[i].port.type == PORT_UNKNOWN)
			return &serial8250_ports[i];

	return NULL;
}

/**
 *	serial8250_register_port - register a serial port
 *	@port: serial port template
 *
 *	Configure the serial port specified by the request. If the
 *	port exists and is in use, it is hung up and unregistered
 *	first.
 *
 *	The port is then probed and if necessary the IRQ is autodetected
 *	If this fails an error is returned.
 *
 *	On success the port is ready to use and the line number is returned.
 */
int serial8250_register_port(struct uart_port *port)
{
	struct uart_8250_port *uart;
	int ret = -ENOSPC;

	if (port->uartclk == 0)
		return -EINVAL;

	mutex_lock(&serial_mutex);

	uart = serial8250_find_match_or_unused(port);
	if (uart) {
		uart_remove_one_port(&serial8250_reg, &uart->port);

		uart->port.iobase   = port->iobase;
		uart->port.membase  = port->membase;
		uart->port.irq      = port->irq;
		uart->port.uartclk  = port->uartclk;
		uart->port.fifosize = port->fifosize;
		uart->port.regshift = port->regshift;
		uart->port.iotype   = port->iotype;
		uart->port.flags    = port->flags | UPF_BOOT_AUTOCONF;
		uart->port.mapbase  = port->mapbase;
		if (port->dev)
			uart->port.dev = port->dev;

		ret = uart_add_one_port(&serial8250_reg, &uart->port);
		if (ret == 0)
			ret = uart->port.line;
	}
	mutex_unlock(&serial_mutex);