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linux/drivers/serial/21285.c
Russell King b129a8ccd5 [SERIAL] Clean up and fix tty transmission start/stoping 
The start_tx and stop_tx methods were passed a flag to indicate
whether the start/stop was from the tty start/stop callbacks, and
some drivers used this flag to decide whether to ask the UART to
immediately stop transmission (where the UART supports such a
feature.)

There are other cases when we wish this to occur - when CTS is
lowered, or if we change from soft to hard flow control and CTS
is inactive.  In these cases, this flag was false, and we would
allow the transmitter to drain before stopping.

There is really only one case where we want to let the transmitter
drain before disabling, and that's when we run out of characters
to send.

Hence, re-jig the start_tx and stop_tx methods to eliminate this
flag, and introduce new functions for the special "disable and
allow transmitter to drain" case.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-08-31 10:12:14 +01:00

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/*
* linux/drivers/char/21285.c
*
* Driver for the serial port on the 21285 StrongArm-110 core logic chip.
*
* Based on drivers/char/serial.c
*
* $Id: 21285.c,v 1.37 2002/07/28 10:03:27 rmk Exp $
*/
#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/device.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/mach-types.h>
#include <asm/hardware/dec21285.h>
#include <asm/hardware.h>
#define BAUD_BASE (mem_fclk_21285/64)
#define SERIAL_21285_NAME "ttyFB"
#define SERIAL_21285_MAJOR 204
#define SERIAL_21285_MINOR 4
#define RXSTAT_DUMMY_READ 0x80000000
#define RXSTAT_FRAME (1 << 0)
#define RXSTAT_PARITY (1 << 1)
#define RXSTAT_OVERRUN (1 << 2)
#define RXSTAT_ANYERR (RXSTAT_FRAME|RXSTAT_PARITY|RXSTAT_OVERRUN)
#define H_UBRLCR_BREAK (1 << 0)
#define H_UBRLCR_PARENB (1 << 1)
#define H_UBRLCR_PAREVN (1 << 2)
#define H_UBRLCR_STOPB (1 << 3)
#define H_UBRLCR_FIFO (1 << 4)
static const char serial21285_name[] = "Footbridge UART";
#define tx_enabled(port) ((port)->unused[0])
#define rx_enabled(port) ((port)->unused[1])
/*
* The documented expression for selecting the divisor is:
* BAUD_BASE / baud - 1
* However, typically BAUD_BASE is not divisible by baud, so
* we want to select the divisor that gives us the minimum
* error. Therefore, we want:
* int(BAUD_BASE / baud - 0.5) ->
* int(BAUD_BASE / baud - (baud >> 1) / baud) ->
* int((BAUD_BASE - (baud >> 1)) / baud)
*/
static void serial21285_stop_tx(struct uart_port *port)
{
if (tx_enabled(port)) {
disable_irq(IRQ_CONTX);
tx_enabled(port) = 0;
}
}
static void serial21285_start_tx(struct uart_port *port)
{
if (!tx_enabled(port)) {
enable_irq(IRQ_CONTX);
tx_enabled(port) = 1;
}
}
static void serial21285_stop_rx(struct uart_port *port)
{
if (rx_enabled(port)) {
disable_irq(IRQ_CONRX);
rx_enabled(port) = 0;
}
}
static void serial21285_enable_ms(struct uart_port *port)
{
}
static irqreturn_t serial21285_rx_chars(int irq, void *dev_id, struct pt_regs *regs)
{
struct uart_port *port = dev_id;
struct tty_struct *tty = port->info->tty;
unsigned int status, ch, flag, rxs, max_count = 256;
status = *CSR_UARTFLG;
while (!(status & 0x10) && max_count--) {
if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
if (tty->low_latency)
tty_flip_buffer_push(tty);
/*
* If this failed then we will throw away the
* bytes but must do so to clear interrupts
*/
}
ch = *CSR_UARTDR;
flag = TTY_NORMAL;
port->icount.rx++;
rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
if (unlikely(rxs & RXSTAT_ANYERR)) {
if (rxs & RXSTAT_PARITY)
port->icount.parity++;
else if (rxs & RXSTAT_FRAME)
port->icount.frame++;
if (rxs & RXSTAT_OVERRUN)
port->icount.overrun++;
rxs &= port->read_status_mask;
if (rxs & RXSTAT_PARITY)
flag = TTY_PARITY;
else if (rxs & RXSTAT_FRAME)
flag = TTY_FRAME;
}
uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
status = *CSR_UARTFLG;
}
tty_flip_buffer_push(tty);
return IRQ_HANDLED;
}
static irqreturn_t serial21285_tx_chars(int irq, void *dev_id, struct pt_regs *regs)
{
struct uart_port *port = dev_id;
struct circ_buf *xmit = &port->info->xmit;
int count = 256;
if (port->x_char) {
*CSR_UARTDR = port->x_char;
port->icount.tx++;
port->x_char = 0;
goto out;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
serial21285_stop_tx(port);
goto out;
}
do {
*CSR_UARTDR = 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 && !(*CSR_UARTFLG & 0x20));
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
if (uart_circ_empty(xmit))
serial21285_stop_tx(port);
out:
return IRQ_HANDLED;
}
static unsigned int serial21285_tx_empty(struct uart_port *port)
{
return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
}
/* no modem control lines */
static unsigned int serial21285_get_mctrl(struct uart_port *port)
{
return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
}
static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}
static void serial21285_break_ctl(struct uart_port *port, int break_state)
{
unsigned long flags;
unsigned int h_lcr;
spin_lock_irqsave(&port->lock, flags);
h_lcr = *CSR_H_UBRLCR;
if (break_state)
h_lcr |= H_UBRLCR_BREAK;
else
h_lcr &= ~H_UBRLCR_BREAK;
*CSR_H_UBRLCR = h_lcr;
spin_unlock_irqrestore(&port->lock, flags);
}
static int serial21285_startup(struct uart_port *port)
{
int ret;
tx_enabled(port) = 1;
rx_enabled(port) = 1;
ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
serial21285_name, port);
if (ret == 0) {
ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
serial21285_name, port);
if (ret)
free_irq(IRQ_CONRX, port);
}
return ret;
}
static void serial21285_shutdown(struct uart_port *port)
{
free_irq(IRQ_CONTX, port);
free_irq(IRQ_CONRX, port);
}
static void
serial21285_set_termios(struct uart_port *port, struct termios *termios,
struct termios *old)
{
unsigned long flags;
unsigned int baud, quot, h_lcr;
/*
* We don't support modem control lines.
*/
termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
termios->c_cflag |= CLOCAL;
/*
* We don't support BREAK character recognition.
*/
termios->c_iflag &= ~(IGNBRK | BRKINT);
/*
* Ask the core to calculate the divisor for us.
*/
baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
quot = uart_get_divisor(port, baud);
switch (termios->c_cflag & CSIZE) {
case CS5:
h_lcr = 0x00;
break;
case CS6:
h_lcr = 0x20;
break;
case CS7:
h_lcr = 0x40;
break;
default: /* CS8 */
h_lcr = 0x60;
break;
}
if (termios->c_cflag & CSTOPB)
h_lcr |= H_UBRLCR_STOPB;
if (termios->c_cflag & PARENB) {
h_lcr |= H_UBRLCR_PARENB;
if (!(termios->c_cflag & PARODD))
h_lcr |= H_UBRLCR_PAREVN;
}
if (port->fifosize)
h_lcr |= H_UBRLCR_FIFO;
spin_lock_irqsave(&port->lock, flags);
/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud);
/*
* Which character status flags are we interested in?
*/
port->read_status_mask = RXSTAT_OVERRUN;
if (termios->c_iflag & INPCK)
port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
/*
* Which character status flags should we ignore?
*/
port->ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
port->ignore_status_mask |= RXSTAT_OVERRUN;
/*
* Ignore all characters if CREAD is not set.
*/
if ((termios->c_cflag & CREAD) == 0)
port->ignore_status_mask |= RXSTAT_DUMMY_READ;
quot -= 1;
*CSR_UARTCON = 0;
*CSR_L_UBRLCR = quot & 0xff;
*CSR_M_UBRLCR = (quot >> 8) & 0x0f;
*CSR_H_UBRLCR = h_lcr;
*CSR_UARTCON = 1;
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *serial21285_type(struct uart_port *port)
{
return port->type == PORT_21285 ? "DC21285" : NULL;
}
static void serial21285_release_port(struct uart_port *port)
{
release_mem_region(port->mapbase, 32);
}
static int serial21285_request_port(struct uart_port *port)
{
return request_mem_region(port->mapbase, 32, serial21285_name)
!= NULL ? 0 : -EBUSY;
}
static void serial21285_config_port(struct uart_port *port, int flags)
{
if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
port->type = PORT_21285;
}
/*
* verify the new serial_struct (for TIOCSSERIAL).
*/
static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
{
int ret = 0;
if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
ret = -EINVAL;
if (ser->irq != NO_IRQ)
ret = -EINVAL;
if (ser->baud_base != port->uartclk / 16)
ret = -EINVAL;
return ret;
}
static struct uart_ops serial21285_ops = {
.tx_empty = serial21285_tx_empty,
.get_mctrl = serial21285_get_mctrl,
.set_mctrl = serial21285_set_mctrl,
.stop_tx = serial21285_stop_tx,
.start_tx = serial21285_start_tx,
.stop_rx = serial21285_stop_rx,
.enable_ms = serial21285_enable_ms,
.break_ctl = serial21285_break_ctl,
.startup = serial21285_startup,
.shutdown = serial21285_shutdown,
.set_termios = serial21285_set_termios,
.type = serial21285_type,
.release_port = serial21285_release_port,
.request_port = serial21285_request_port,
.config_port = serial21285_config_port,
.verify_port = serial21285_verify_port,
};
static struct uart_port serial21285_port = {
.mapbase = 0x42000160,
.iotype = SERIAL_IO_MEM,
.irq = NO_IRQ,
.fifosize = 16,
.ops = &serial21285_ops,
.flags = ASYNC_BOOT_AUTOCONF,
};
static void serial21285_setup_ports(void)
{
serial21285_port.uartclk = mem_fclk_21285 / 4;
}
#ifdef CONFIG_SERIAL_21285_CONSOLE
static void
serial21285_console_write(struct console *co, const char *s,
unsigned int count)
{
int i;
for (i = 0; i < count; i++) {
while (*CSR_UARTFLG & 0x20)
barrier();
*CSR_UARTDR = s[i];
if (s[i] == '\n') {
while (*CSR_UARTFLG & 0x20)
barrier();
*CSR_UARTDR = '\r';
}
}
}
static void __init
serial21285_get_options(struct uart_port *port, int *baud,
int *parity, int *bits)
{
if (*CSR_UARTCON == 1) {
unsigned int tmp;
tmp = *CSR_H_UBRLCR;
switch (tmp & 0x60) {
case 0x00:
*bits = 5;
break;
case 0x20:
*bits = 6;
break;
case 0x40:
*bits = 7;
break;
default:
case 0x60:
*bits = 8;
break;
}
if (tmp & H_UBRLCR_PARENB) {
*parity = 'o';
if (tmp & H_UBRLCR_PAREVN)
*parity = 'e';
}
tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
*baud = port->uartclk / (16 * (tmp + 1));
}
}
static int __init serial21285_console_setup(struct console *co, char *options)
{
struct uart_port *port = &serial21285_port;
int baud = 9600;
int bits = 8;
int parity = 'n';
int flow = 'n';
if (machine_is_personal_server())
baud = 57600;
/*
* Check whether an invalid uart number has been specified, and
* if so, search for the first available port that does have
* console support.
*/
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
serial21285_get_options(port, &baud, &parity, &bits);
return uart_set_options(port, co, baud, parity, bits, flow);
}
extern struct uart_driver serial21285_reg;
static struct console serial21285_console =
{
.name = SERIAL_21285_NAME,
.write = serial21285_console_write,
.device = uart_console_device,
.setup = serial21285_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &serial21285_reg,
};
static int __init rs285_console_init(void)
{
serial21285_setup_ports();
register_console(&serial21285_console);
return 0;
}
console_initcall(rs285_console_init);
#define SERIAL_21285_CONSOLE &serial21285_console
#else
#define SERIAL_21285_CONSOLE NULL
#endif
static struct uart_driver serial21285_reg = {
.owner = THIS_MODULE,
.driver_name = "ttyFB",
.dev_name = "ttyFB",
.devfs_name = "ttyFB",
.major = SERIAL_21285_MAJOR,
.minor = SERIAL_21285_MINOR,
.nr = 1,
.cons = SERIAL_21285_CONSOLE,
};
static int __init serial21285_init(void)
{
int ret;
printk(KERN_INFO "Serial: 21285 driver $Revision: 1.37 $\n");
serial21285_setup_ports();
ret = uart_register_driver(&serial21285_reg);
if (ret == 0)
uart_add_one_port(&serial21285_reg, &serial21285_port);
return ret;
}
static void __exit serial21285_exit(void)
{
uart_remove_one_port(&serial21285_reg, &serial21285_port);
uart_unregister_driver(&serial21285_reg);
}
module_init(serial21285_init);
module_exit(serial21285_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver $Revision: 1.37 $");
MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);
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