mux.c

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/*
** mux.c:
**	serial driver for the Mux console found in some PA-RISC servers.
**
**	(c) Copyright 2002 Ryan Bradetich
**	(c) Copyright 2002 Hewlett-Packard Company
**
** 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 Driver currently only supports the console (port 0) on the MUX.
** Additional work will be needed on this driver to enable the full
** functionality of the MUX.
**
*/

#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/slab.h>
#include <linux/delay.h> /* for udelay */
#include <linux/device.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/parisc-device.h>

#ifdef CONFIG_MAGIC_SYSRQ
#include <linux/sysrq.h>
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>

#define MUX_OFFSET 0x800
#define MUX_LINE_OFFSET 0x80

#define MUX_FIFO_SIZE 255
#define MUX_POLL_DELAY (30 * HZ / 1000)

#define IO_DATA_REG_OFFSET 0x3c
#define IO_DCOUNT_REG_OFFSET 0x40

#define MUX_EOFIFO(status) ((status & 0xF000) == 0xF000)
#define MUX_STATUS(status) ((status & 0xF000) == 0x8000)
#define MUX_BREAK(status) ((status & 0xF000) == 0x2000)

#define MUX_NR 256
static unsigned int port_cnt __read_mostly;
struct mux_port {
	struct uart_port port;
	int enabled;
};
static struct mux_port mux_ports[MUX_NR];

static struct uart_driver mux_driver = {
	.owner = THIS_MODULE,
	.driver_name = "ttyB",
	.dev_name = "ttyB",
	.major = MUX_MAJOR,
	.minor = 0,
	.nr = MUX_NR,
};

static struct timer_list mux_timer;

#define UART_PUT_CHAR(p, c) __raw_writel((c), (p)->membase + IO_DATA_REG_OFFSET)
#define UART_GET_FIFO_CNT(p) __raw_readl((p)->membase + IO_DCOUNT_REG_OFFSET)

/**
 * get_mux_port_count - Get the number of available ports on the Mux.
 * @dev: The parisc device.
 *
 * This function is used to determine the number of ports the Mux
 * supports.  The IODC data reports the number of ports the Mux
 * can support, but there are cases where not all the Mux ports
 * are connected.  This function can override the IODC and
 * return the true port count.
 */
static int __init get_mux_port_count(struct parisc_device *dev)
{
	int status;
	u8 iodc_data[32];
	unsigned long bytecnt;

	/* If this is the built-in Mux for the K-Class (Eole CAP/MUX),
	 * we only need to allocate resources for 1 port since the
	 * other 7 ports are not connected.
	 */
	if(dev->id.hversion == 0x15)
		return 1;

	status = pdc_iodc_read(&bytecnt, dev->hpa.start, 0, iodc_data, 32);
	BUG_ON(status != PDC_OK);

	/* Return the number of ports specified in the iodc data. */
	return ((((iodc_data)[4] & 0xf0) >> 4) * 8) + 8;
}

/**
 * mux_tx_empty - Check if the transmitter fifo is empty.
 * @port: Ptr to the uart_port.
 *
 * This function test if the transmitter fifo for the port
 * described by 'port' is empty.  If it is empty, this function
 * should return TIOCSER_TEMT, otherwise return 0.
 */
static unsigned int mux_tx_empty(struct uart_port *port)
{
	return UART_GET_FIFO_CNT(port) ? 0 : TIOCSER_TEMT;
} 

/**
 * mux_set_mctrl - Set the current state of the modem control inputs.
 * @ports: Ptr to the uart_port.
 * @mctrl: Modem control bits.
 *
 * The Serial MUX does not support CTS, DCD or DSR so this function
 * is ignored.
 */
static void mux_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

/**
 * mux_get_mctrl - Returns the current state of modem control inputs.
 * @port: Ptr to the uart_port.
 *
 * The Serial MUX does not support CTS, DCD or DSR so these lines are
 * treated as permanently active.
 */
static unsigned int mux_get_mctrl(struct uart_port *port)
{ 
	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
}

/**
 * mux_stop_tx - Stop transmitting characters.
 * @port: Ptr to the uart_port.
 *
 * The Serial MUX does not support this function.
 */
static void mux_stop_tx(struct uart_port *port)
{
}

/**
 * mux_start_tx - Start transmitting characters.
 * @port: Ptr to the uart_port.
 *
 * The Serial Mux does not support this function.
 */
static void mux_start_tx(struct uart_port *port)
{
}

/**
 * mux_stop_rx - Stop receiving characters.
 * @port: Ptr to the uart_port.
 *
 * The Serial Mux does not support this function.
 */
static void mux_stop_rx(struct uart_port *port)
{
}

/**
 * mux_enable_ms - Enable modum status interrupts.
 * @port: Ptr to the uart_port.
 *
 * The Serial Mux does not support this function.
 */
static void mux_enable_ms(struct uart_port *port)
{
}

/**
 * mux_break_ctl - Control the transmitssion of a break signal.
 * @port: Ptr to the uart_port.
 * @break_state: Raise/Lower the break signal.
 *
 * The Serial Mux does not support this function.
 */
static void mux_break_ctl(struct uart_port *port, int break_state)
{
}

/**
 * mux_write - Write chars to the mux fifo.
 * @port: Ptr to the uart_port.
 *
 * This function writes all the data from the uart buffer to
 * the mux fifo.
 */
static void mux_write(struct uart_port *port)
{
	int count;
	struct circ_buf *xmit = &port->info->xmit;

	if(port->x_char) {
		UART_PUT_CHAR(port, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}

	if(uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		mux_stop_tx(port);
		return;
	}

	count = (port->fifosize) - UART_GET_FIFO_CNT(port);
	do {
		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if(uart_circ_empty(xmit))
			break;

	} while(--count > 0);

	while(UART_GET_FIFO_CNT(port)) 
		udelay(1);

	if(uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(port);

	if (uart_circ_empty(xmit))
		mux_stop_tx(port);
}

/**
 * mux_read - Read chars from the mux fifo.
 * @port: Ptr to the uart_port.
 *
 * This reads all available data from the mux's fifo and pushes
 * the data to the tty layer.
 */
static void mux_read(struct uart_port *port)
{
	int data;
	struct tty_struct *tty = port->info->tty;
	__u32 start_count = port->icount.rx;

	while(1) {
		data = __raw_readl(port->membase + IO_DATA_REG_OFFSET);

		if (MUX_STATUS(data))
			continue;

		if (MUX_EOFIFO(data))
			break;

		port->icount.rx++;

		if (MUX_BREAK(data)) {
			port->icount.brk++;
			if(uart_handle_break(port))
				continue;
		}

		if (uart_handle_sysrq_char(port, data & 0xffu))
			continue;

		tty_insert_flip_char(tty, data & 0xFF, TTY_NORMAL);
	}
	
	if (start_count != port->icount.rx) {
		tty_flip_buffer_push(tty);
	}
}

/**
 * mux_startup - Initialize the port.
 * @port: Ptr to the uart_port.
 *
 * Grab any resources needed for this port and start the
 * mux timer.
 */
static int mux_startup(struct uart_port *port)
{
	mux_ports[port->line].enabled = 1;
	return 0;
}

/**
 * mux_shutdown - Disable the port.
 * @port: Ptr to the uart_port.
 *
 * Release any resources needed for the port.
 */
static void mux_shutdown(struct uart_port *port)
{
	mux_ports[port->line].enabled = 0;
}

/**
 * mux_set_termios - Chane port parameters.
 * @port: Ptr to the uart_port.
 * @termios: new termios settings.
 * @old: old termios settings.
 *
 * The Serial Mux does not support this function.
 */
static void
mux_set_termios(struct uart_port *port, struct ktermios *termios,
	        struct ktermios *old)
{
}

/**
 * mux_type - Describe the port.
 * @port: Ptr to the uart_port.
 *