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linux-next/drivers/serial/21285.c
David Howells 7d12e780e0 IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 15:10:12 +01:00

514 lines
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/*
* linux/drivers/serial/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/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 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--) {
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 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 = UPIO_MEM,
.irq = NO_IRQ,
.fifosize = 16,
.ops = &serial21285_ops,
.flags = UPF_BOOT_AUTOCONF,
};
static void serial21285_setup_ports(void)
{
serial21285_port.uartclk = mem_fclk_21285 / 4;
}
#ifdef CONFIG_SERIAL_21285_CONSOLE
static void serial21285_console_putchar(struct uart_port *port, int ch)
{
while (*CSR_UARTFLG & 0x20)
barrier();
*CSR_UARTDR = ch;
}
static void
serial21285_console_write(struct console *co, const char *s,
unsigned int count)
{
uart_console_write(&serial21285_port, s, count, serial21285_console_putchar);
}
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);
}
static 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",
.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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