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linux/drivers/serial/clps711x.c
Alan Cox 33f0f88f1c [PATCH] TTY layer buffering revamp 
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.

This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.

When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.

For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).

Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.

The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.

I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.

Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real.  That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.

Description:

tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification].  It
does now also return the number of chars inserted

There are also

tty_buffer_request_room(tty, len)

which asks for a buffer block of the length requested and returns the space
found.  This improves efficiency with hardware that knows how much to
transfer.

and tty_insert_flip_string_flags(tty, str, flags, len)

to insert a string of characters and flags

For a smart interface the usual code is

    len = tty_request_buffer_room(tty, amount_hardware_says);
    tty_insert_flip_string(tty, buffer_from_card, len);

More description!

At the moment tty buffers are attached directly to the tty.  This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)

I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers.  This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.

So far so good.  Lots of drivers reference tty->flip.*.  Several of them also
call directly and unsafely into function pointers it provides.  This will all
break.  Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.

At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say

 int tty_buffer_request_room(tty, size)

Try and ensure at least size bytes are available, returns actual room (may be
zero).  At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative.  (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space.  The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.

 int tty_insert_flip_char(tty, ch, flag)

As before insert a character if there is room.  Now returns 1 for success, 0
for failure.

 int tty_insert_flip_string(tty, str, len)

Insert a block of non error characters.  Returns the number inserted.

 int tty_prepare_flip_string(tty, strptr, len)

Adjust the buffer to allow len characters to be added.  Returns a buffer
pointer in strptr and the length available.  This allows for hardware that
needs to use functions like insl or mencpy_fromio.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:59 -08:00

592 lines
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/*
* linux/drivers/char/clps711x.c
*
* Driver for CLPS711x 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: clps711x.c,v 1.42 2002/07/28 10:03:28 rmk Exp $
*
*/
#include <linux/config.h>
#if defined(CONFIG_SERIAL_CLPS711X_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/hardware/clps7111.h>
#define UART_NR 2
#define SERIAL_CLPS711X_MAJOR 204
#define SERIAL_CLPS711X_MINOR 40
#define SERIAL_CLPS711X_NR UART_NR
/*
* We use the relevant SYSCON register as a base address for these ports.
*/
#define UBRLCR(port) ((port)->iobase + UBRLCR1 - SYSCON1)
#define UARTDR(port) ((port)->iobase + UARTDR1 - SYSCON1)
#define SYSFLG(port) ((port)->iobase + SYSFLG1 - SYSCON1)
#define SYSCON(port) ((port)->iobase + SYSCON1 - SYSCON1)
#define TX_IRQ(port) ((port)->irq)
#define RX_IRQ(port) ((port)->irq + 1)
#define UART_ANY_ERR (UARTDR_FRMERR | UARTDR_PARERR | UARTDR_OVERR)
#define tx_enabled(port) ((port)->unused[0])
static void clps711xuart_stop_tx(struct uart_port *port)
{
if (tx_enabled(port)) {
disable_irq(TX_IRQ(port));
tx_enabled(port) = 0;
}
}
static void clps711xuart_start_tx(struct uart_port *port)
{
if (!tx_enabled(port)) {
enable_irq(TX_IRQ(port));
tx_enabled(port) = 1;
}
}
static void clps711xuart_stop_rx(struct uart_port *port)
{
disable_irq(RX_IRQ(port));
}
static void clps711xuart_enable_ms(struct uart_port *port)
{
}
static irqreturn_t clps711xuart_int_rx(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, flg;
status = clps_readl(SYSFLG(port));
while (!(status & SYSFLG_URXFE)) {
ch = clps_readl(UARTDR(port));
port->icount.rx++;
flg = TTY_NORMAL;
/*
* Note that the error handling code is
* out of the main execution path
*/
if (unlikely(ch & UART_ANY_ERR)) {
if (ch & UARTDR_PARERR)
port->icount.parity++;
else if (ch & UARTDR_FRMERR)
port->icount.frame++;
if (ch & UARTDR_OVERR)
port->icount.overrun++;
ch &= port->read_status_mask;
if (ch & UARTDR_PARERR)
flg = TTY_PARITY;
else if (ch & UARTDR_FRMERR)
flg = TTY_FRAME;
#ifdef SUPPORT_SYSRQ
port->sysrq = 0;
#endif
}
if (uart_handle_sysrq_char(port, ch, regs))
goto ignore_char;
/*
* CHECK: does overrun affect the current character?
* ASSUMPTION: it does not.
*/
uart_insert_char(port, ch, UARTDR_OVERR, ch, flg);
ignore_char:
status = clps_readl(SYSFLG(port));
}
tty_flip_buffer_push(tty);
return IRQ_HANDLED;
}
static irqreturn_t clps711xuart_int_tx(int irq, void *dev_id, struct pt_regs *regs)
{
struct uart_port *port = dev_id;
struct circ_buf *xmit = &port->info->xmit;
int count;
if (port->x_char) {
clps_writel(port->x_char, UARTDR(port));
port->icount.tx++;
port->x_char = 0;
return IRQ_HANDLED;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
clps711xuart_stop_tx(port);
return IRQ_HANDLED;
}
count = port->fifosize >> 1;
do {
clps_writel(xmit->buf[xmit->tail], UARTDR(port));
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
port->icount.tx++;
if (uart_circ_empty(xmit))
break;
} while (--count > 0);
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
if (uart_circ_empty(xmit))
clps711xuart_stop_tx(port);
return IRQ_HANDLED;
}
static unsigned int clps711xuart_tx_empty(struct uart_port *port)
{
unsigned int status = clps_readl(SYSFLG(port));
return status & SYSFLG_UBUSY ? 0 : TIOCSER_TEMT;
}
static unsigned int clps711xuart_get_mctrl(struct uart_port *port)
{
unsigned int port_addr;
unsigned int result = 0;
unsigned int status;
port_addr = SYSFLG(port);
if (port_addr == SYSFLG1) {
status = clps_readl(SYSFLG1);
if (status & SYSFLG1_DCD)
result |= TIOCM_CAR;
if (status & SYSFLG1_DSR)
result |= TIOCM_DSR;
if (status & SYSFLG1_CTS)
result |= TIOCM_CTS;
}
return result;
}
static void
clps711xuart_set_mctrl_null(struct uart_port *port, unsigned int mctrl)
{
}
static void clps711xuart_break_ctl(struct uart_port *port, int break_state)
{
unsigned long flags;
unsigned int ubrlcr;
spin_lock_irqsave(&port->lock, flags);
ubrlcr = clps_readl(UBRLCR(port));
if (break_state == -1)
ubrlcr |= UBRLCR_BREAK;
else
ubrlcr &= ~UBRLCR_BREAK;
clps_writel(ubrlcr, UBRLCR(port));
spin_unlock_irqrestore(&port->lock, flags);
}
static int clps711xuart_startup(struct uart_port *port)
{
unsigned int syscon;
int retval;
tx_enabled(port) = 1;
/*
* Allocate the IRQs
*/
retval = request_irq(TX_IRQ(port), clps711xuart_int_tx, 0,
"clps711xuart_tx", port);
if (retval)
return retval;
retval = request_irq(RX_IRQ(port), clps711xuart_int_rx, 0,
"clps711xuart_rx", port);
if (retval) {
free_irq(TX_IRQ(port), port);
return retval;
}
/*
* enable the port
*/
syscon = clps_readl(SYSCON(port));
syscon |= SYSCON_UARTEN;
clps_writel(syscon, SYSCON(port));
return 0;
}
static void clps711xuart_shutdown(struct uart_port *port)
{
unsigned int ubrlcr, syscon;
/*
* Free the interrupt
*/
free_irq(TX_IRQ(port), port); /* TX interrupt */
free_irq(RX_IRQ(port), port); /* RX interrupt */
/*
* disable the port
*/
syscon = clps_readl(SYSCON(port));
syscon &= ~SYSCON_UARTEN;
clps_writel(syscon, SYSCON(port));
/*
* disable break condition and fifos
*/
ubrlcr = clps_readl(UBRLCR(port));
ubrlcr &= ~(UBRLCR_FIFOEN | UBRLCR_BREAK);
clps_writel(ubrlcr, UBRLCR(port));
}
static void
clps711xuart_set_termios(struct uart_port *port, struct termios *termios,
struct termios *old)
{
unsigned int ubrlcr, baud, quot;
unsigned long flags;
/*
* We don't implement CREAD.
*/
termios->c_cflag |= CREAD;
/*
* 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:
ubrlcr = UBRLCR_WRDLEN5;
break;
case CS6:
ubrlcr = UBRLCR_WRDLEN6;
break;
case CS7:
ubrlcr = UBRLCR_WRDLEN7;
break;
default: // CS8
ubrlcr = UBRLCR_WRDLEN8;
break;
}
if (termios->c_cflag & CSTOPB)
ubrlcr |= UBRLCR_XSTOP;
if (termios->c_cflag & PARENB) {
ubrlcr |= UBRLCR_PRTEN;
if (!(termios->c_cflag & PARODD))
ubrlcr |= UBRLCR_EVENPRT;
}
if (port->fifosize > 1)
ubrlcr |= UBRLCR_FIFOEN;
spin_lock_irqsave(&port->lock, flags);
/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud);
port->read_status_mask = UARTDR_OVERR;
if (termios->c_iflag & INPCK)
port->read_status_mask |= UARTDR_PARERR | UARTDR_FRMERR;
/*
* Characters to ignore
*/
port->ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= UARTDR_FRMERR | UARTDR_PARERR;
if (termios->c_iflag & IGNBRK) {
/*
* If we're ignoring parity and break indicators,
* ignore overruns to (for real raw support).
*/
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= UARTDR_OVERR;
}
quot -= 1;
clps_writel(ubrlcr | quot, UBRLCR(port));
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *clps711xuart_type(struct uart_port *port)
{
return port->type == PORT_CLPS711X ? "CLPS711x" : NULL;
}
/*
* Configure/autoconfigure the port.
*/
static void clps711xuart_config_port(struct uart_port *port, int flags)
{
if (flags & UART_CONFIG_TYPE)
port->type = PORT_CLPS711X;
}
static void clps711xuart_release_port(struct uart_port *port)
{
}
static int clps711xuart_request_port(struct uart_port *port)
{
return 0;
}
static struct uart_ops clps711x_pops = {
.tx_empty = clps711xuart_tx_empty,
.set_mctrl = clps711xuart_set_mctrl_null,
.get_mctrl = clps711xuart_get_mctrl,
.stop_tx = clps711xuart_stop_tx,
.start_tx = clps711xuart_start_tx,
.stop_rx = clps711xuart_stop_rx,
.enable_ms = clps711xuart_enable_ms,
.break_ctl = clps711xuart_break_ctl,
.startup = clps711xuart_startup,
.shutdown = clps711xuart_shutdown,
.set_termios = clps711xuart_set_termios,
.type = clps711xuart_type,
.config_port = clps711xuart_config_port,
.release_port = clps711xuart_release_port,
.request_port = clps711xuart_request_port,
};
static struct uart_port clps711x_ports[UART_NR] = {
{
.iobase = SYSCON1,
.irq = IRQ_UTXINT1, /* IRQ_URXINT1, IRQ_UMSINT */
.uartclk = 3686400,
.fifosize = 16,
.ops = &clps711x_pops,
.line = 0,
.flags = ASYNC_BOOT_AUTOCONF,
},
{
.iobase = SYSCON2,
.irq = IRQ_UTXINT2, /* IRQ_URXINT2 */
.uartclk = 3686400,
.fifosize = 16,
.ops = &clps711x_pops,
.line = 1,
.flags = ASYNC_BOOT_AUTOCONF,
}
};
#ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
/*
* 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.
*
* Note that this is called with interrupts already disabled
*/
static void
clps711xuart_console_write(struct console *co, const char *s,
unsigned int count)
{
struct uart_port *port = clps711x_ports + co->index;
unsigned int status, syscon;
int i;
/*
* Ensure that the port is enabled.
*/
syscon = clps_readl(SYSCON(port));
clps_writel(syscon | SYSCON_UARTEN, SYSCON(port));
/*
* Now, do each character
*/
for (i = 0; i < count; i++) {
do {
status = clps_readl(SYSFLG(port));
} while (status & SYSFLG_UTXFF);
clps_writel(s[i], UARTDR(port));
if (s[i] == '\n') {
do {
status = clps_readl(SYSFLG(port));
} while (status & SYSFLG_UTXFF);
clps_writel('\r', UARTDR(port));
}
}
/*
* Finally, wait for transmitter to become empty
* and restore the uart state.
*/
do {
status = clps_readl(SYSFLG(port));
} while (status & SYSFLG_UBUSY);
clps_writel(syscon, SYSCON(port));
}
static void __init
clps711xuart_console_get_options(struct uart_port *port, int *baud,
int *parity, int *bits)
{
if (clps_readl(SYSCON(port)) & SYSCON_UARTEN) {
unsigned int ubrlcr, quot;
ubrlcr = clps_readl(UBRLCR(port));
*parity = 'n';
if (ubrlcr & UBRLCR_PRTEN) {
if (ubrlcr & UBRLCR_EVENPRT)
*parity = 'e';
else
*parity = 'o';
}
if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
*bits = 7;
else
*bits = 8;
quot = ubrlcr & UBRLCR_BAUD_MASK;
*baud = port->uartclk / (16 * (quot + 1));
}
}
static int __init clps711xuart_console_setup(struct console *co, char *options)
{
struct uart_port *port;
int baud = 38400;
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.
*/
port = uart_get_console(clps711x_ports, UART_NR, co);
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
clps711xuart_console_get_options(port, &baud, &parity, &bits);
return uart_set_options(port, co, baud, parity, bits, flow);
}
static struct uart_driver clps711x_reg;
static struct console clps711x_console = {
.name = "ttyCL",
.write = clps711xuart_console_write,
.device = uart_console_device,
.setup = clps711xuart_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &clps711x_reg,
};
static int __init clps711xuart_console_init(void)
{
register_console(&clps711x_console);
return 0;
}
console_initcall(clps711xuart_console_init);
#define CLPS711X_CONSOLE &clps711x_console
#else
#define CLPS711X_CONSOLE NULL
#endif
static struct uart_driver clps711x_reg = {
.driver_name = "ttyCL",
.dev_name = "ttyCL",
.major = SERIAL_CLPS711X_MAJOR,
.minor = SERIAL_CLPS711X_MINOR,
.nr = UART_NR,
.cons = CLPS711X_CONSOLE,
};
static int __init clps711xuart_init(void)
{
int ret, i;
printk(KERN_INFO "Serial: CLPS711x driver $Revision: 1.42 $\n");
ret = uart_register_driver(&clps711x_reg);
if (ret)
return ret;
for (i = 0; i < UART_NR; i++)
uart_add_one_port(&clps711x_reg, &clps711x_ports[i]);
return 0;
}
static void __exit clps711xuart_exit(void)
{
int i;
for (i = 0; i < UART_NR; i++)
uart_remove_one_port(&clps711x_reg, &clps711x_ports[i]);
uart_unregister_driver(&clps711x_reg);
}
module_init(clps711xuart_init);
module_exit(clps711xuart_exit);
MODULE_AUTHOR("Deep Blue Solutions Ltd");
MODULE_DESCRIPTION("CLPS-711x generic serial driver $Revision: 1.42 $");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV(SERIAL_CLPS711X_MAJOR, SERIAL_CLPS711X_MINOR);
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