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linux/drivers/serial/amba-pl010.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

767 lines
18 KiB
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/*
* linux/drivers/char/amba.c
*
* Driver for AMBA 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: amba.c,v 1.41 2002/07/28 10:03:27 rmk Exp $
*
* This is a generic driver for ARM AMBA-type serial ports. They
* have a lot of 16550-like features, but are not register compatible.
* Note that although they do have CTS, DCD and DSR inputs, they do
* not have an RI input, nor do they have DTR or RTS outputs. If
* required, these have to be supplied via some other means (eg, GPIO)
* and hooked into this driver.
*/
#if defined(CONFIG_SERIAL_AMBA_PL010_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/device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/amba/bus.h>
#include <linux/amba/serial.h>
#include <asm/io.h>
#define UART_NR 8
#define SERIAL_AMBA_MAJOR 204
#define SERIAL_AMBA_MINOR 16
#define SERIAL_AMBA_NR UART_NR
#define AMBA_ISR_PASS_LIMIT 256
#define UART_RX_DATA(s) (((s) & UART01x_FR_RXFE) == 0)
#define UART_TX_READY(s) (((s) & UART01x_FR_TXFF) == 0)
#define UART_DUMMY_RSR_RX 256
#define UART_PORT_SIZE 64
/*
* We wrap our port structure around the generic uart_port.
*/
struct uart_amba_port {
struct uart_port port;
struct amba_device *dev;
struct amba_pl010_data *data;
unsigned int old_status;
};
static void pl010_stop_tx(struct uart_port *port)
{
unsigned int cr;
cr = readb(port->membase + UART010_CR);
cr &= ~UART010_CR_TIE;
writel(cr, port->membase + UART010_CR);
}
static void pl010_start_tx(struct uart_port *port)
{
unsigned int cr;
cr = readb(port->membase + UART010_CR);
cr |= UART010_CR_TIE;
writel(cr, port->membase + UART010_CR);
}
static void pl010_stop_rx(struct uart_port *port)
{
unsigned int cr;
cr = readb(port->membase + UART010_CR);
cr &= ~(UART010_CR_RIE | UART010_CR_RTIE);
writel(cr, port->membase + UART010_CR);
}
static void pl010_enable_ms(struct uart_port *port)
{
unsigned int cr;
cr = readb(port->membase + UART010_CR);
cr |= UART010_CR_MSIE;
writel(cr, port->membase + UART010_CR);
}
static void pl010_rx_chars(struct uart_port *port)
{
struct tty_struct *tty = port->info->tty;
unsigned int status, ch, flag, rsr, max_count = 256;
status = readb(port->membase + UART01x_FR);
while (UART_RX_DATA(status) && max_count--) {
ch = readb(port->membase + UART01x_DR);
flag = TTY_NORMAL;
port->icount.rx++;
/*
* Note that the error handling code is
* out of the main execution path
*/
rsr = readb(port->membase + UART01x_RSR) | UART_DUMMY_RSR_RX;
if (unlikely(rsr & UART01x_RSR_ANY)) {
if (rsr & UART01x_RSR_BE) {
rsr &= ~(UART01x_RSR_FE | UART01x_RSR_PE);
port->icount.brk++;
if (uart_handle_break(port))
goto ignore_char;
} else if (rsr & UART01x_RSR_PE)
port->icount.parity++;
else if (rsr & UART01x_RSR_FE)
port->icount.frame++;
if (rsr & UART01x_RSR_OE)
port->icount.overrun++;
rsr &= port->read_status_mask;
if (rsr & UART01x_RSR_BE)
flag = TTY_BREAK;
else if (rsr & UART01x_RSR_PE)
flag = TTY_PARITY;
else if (rsr & UART01x_RSR_FE)
flag = TTY_FRAME;
}
if (uart_handle_sysrq_char(port, ch))
goto ignore_char;
uart_insert_char(port, rsr, UART01x_RSR_OE, ch, flag);
ignore_char:
status = readb(port->membase + UART01x_FR);
}
tty_flip_buffer_push(tty);
return;
}
static void pl010_tx_chars(struct uart_port *port)
{
struct circ_buf *xmit = &port->info->xmit;
int count;
if (port->x_char) {
writel(port->x_char, port->membase + UART01x_DR);
port->icount.tx++;
port->x_char = 0;
return;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
pl010_stop_tx(port);
return;
}
count = port->fifosize >> 1;
do {
writel(xmit->buf[xmit->tail], port->membase + UART01x_DR);
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))
pl010_stop_tx(port);
}
static void pl010_modem_status(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status, delta;
writel(0, uap->port.membase + UART010_ICR);
status = readb(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
delta = status ^ uap->old_status;
uap->old_status = status;
if (!delta)
return;
if (delta & UART01x_FR_DCD)
uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
if (delta & UART01x_FR_DSR)
uap->port.icount.dsr++;
if (delta & UART01x_FR_CTS)
uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
wake_up_interruptible(&uap->port.info->delta_msr_wait);
}
static irqreturn_t pl010_int(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
int handled = 0;
spin_lock(&port->lock);
status = readb(port->membase + UART010_IIR);
if (status) {
do {
if (status & (UART010_IIR_RTIS | UART010_IIR_RIS))
pl010_rx_chars(port);
if (status & UART010_IIR_MIS)
pl010_modem_status(port);
if (status & UART010_IIR_TIS)
pl010_tx_chars(port);
if (pass_counter-- == 0)
break;
status = readb(port->membase + UART010_IIR);
} while (status & (UART010_IIR_RTIS | UART010_IIR_RIS |
UART010_IIR_TIS));
handled = 1;
}
spin_unlock(&port->lock);
return IRQ_RETVAL(handled);
}
static unsigned int pl010_tx_empty(struct uart_port *port)
{
return readb(port->membase + UART01x_FR) & UART01x_FR_BUSY ? 0 : TIOCSER_TEMT;
}
static unsigned int pl010_get_mctrl(struct uart_port *port)
{
unsigned int result = 0;
unsigned int status;
status = readb(port->membase + UART01x_FR);
if (status & UART01x_FR_DCD)
result |= TIOCM_CAR;
if (status & UART01x_FR_DSR)
result |= TIOCM_DSR;
if (status & UART01x_FR_CTS)
result |= TIOCM_CTS;
return result;
}
static void pl010_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
if (uap->data)
uap->data->set_mctrl(uap->dev, uap->port.membase, mctrl);
}
static void pl010_break_ctl(struct uart_port *port, int break_state)
{
unsigned long flags;
unsigned int lcr_h;
spin_lock_irqsave(&port->lock, flags);
lcr_h = readb(port->membase + UART010_LCRH);
if (break_state == -1)
lcr_h |= UART01x_LCRH_BRK;
else
lcr_h &= ~UART01x_LCRH_BRK;
writel(lcr_h, port->membase + UART010_LCRH);
spin_unlock_irqrestore(&port->lock, flags);
}
static int pl010_startup(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
int retval;
/*
* Allocate the IRQ
*/
retval = request_irq(port->irq, pl010_int, 0, "uart-pl010", port);
if (retval)
return retval;
/*
* initialise the old status of the modem signals
*/
uap->old_status = readb(port->membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
/*
* Finally, enable interrupts
*/
writel(UART01x_CR_UARTEN | UART010_CR_RIE | UART010_CR_RTIE,
port->membase + UART010_CR);
return 0;
}
static void pl010_shutdown(struct uart_port *port)
{
/*
* Free the interrupt
*/
free_irq(port->irq, port);
/*
* disable all interrupts, disable the port
*/
writel(0, port->membase + UART010_CR);
/* disable break condition and fifos */
writel(readb(port->membase + UART010_LCRH) &
~(UART01x_LCRH_BRK | UART01x_LCRH_FEN),
port->membase + UART010_LCRH);
}
static void
pl010_set_termios(struct uart_port *port, struct termios *termios,
struct termios *old)
{
unsigned int lcr_h, old_cr;
unsigned long flags;
unsigned int baud, quot;
/*
* 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:
lcr_h = UART01x_LCRH_WLEN_5;
break;
case CS6:
lcr_h = UART01x_LCRH_WLEN_6;
break;
case CS7:
lcr_h = UART01x_LCRH_WLEN_7;
break;
default: // CS8
lcr_h = UART01x_LCRH_WLEN_8;
break;
}
if (termios->c_cflag & CSTOPB)
lcr_h |= UART01x_LCRH_STP2;
if (termios->c_cflag & PARENB) {
lcr_h |= UART01x_LCRH_PEN;
if (!(termios->c_cflag & PARODD))
lcr_h |= UART01x_LCRH_EPS;
}
if (port->fifosize > 1)
lcr_h |= UART01x_LCRH_FEN;
spin_lock_irqsave(&port->lock, flags);
/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud);
port->read_status_mask = UART01x_RSR_OE;
if (termios->c_iflag & INPCK)
port->read_status_mask |= UART01x_RSR_FE | UART01x_RSR_PE;
if (termios->c_iflag & (BRKINT | PARMRK))
port->read_status_mask |= UART01x_RSR_BE;
/*
* Characters to ignore
*/
port->ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= UART01x_RSR_FE | UART01x_RSR_PE;
if (termios->c_iflag & IGNBRK) {
port->ignore_status_mask |= UART01x_RSR_BE;
/*
* If we're ignoring parity and break indicators,
* ignore overruns too (for real raw support).
*/
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= UART01x_RSR_OE;
}
/*
* Ignore all characters if CREAD is not set.
*/
if ((termios->c_cflag & CREAD) == 0)
port->ignore_status_mask |= UART_DUMMY_RSR_RX;
/* first, disable everything */
old_cr = readb(port->membase + UART010_CR) & ~UART010_CR_MSIE;
if (UART_ENABLE_MS(port, termios->c_cflag))
old_cr |= UART010_CR_MSIE;
writel(0, port->membase + UART010_CR);
/* Set baud rate */
quot -= 1;
writel((quot & 0xf00) >> 8, port->membase + UART010_LCRM);
writel(quot & 0xff, port->membase + UART010_LCRL);
/*
* ----------v----------v----------v----------v-----
* NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
* ----------^----------^----------^----------^-----
*/
writel(lcr_h, port->membase + UART010_LCRH);
writel(old_cr, port->membase + UART010_CR);
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *pl010_type(struct uart_port *port)
{
return port->type == PORT_AMBA ? "AMBA" : NULL;
}
/*
* Release the memory region(s) being used by 'port'
*/
static void pl010_release_port(struct uart_port *port)
{
release_mem_region(port->mapbase, UART_PORT_SIZE);
}
/*
* Request the memory region(s) being used by 'port'
*/
static int pl010_request_port(struct uart_port *port)
{
return request_mem_region(port->mapbase, UART_PORT_SIZE, "uart-pl010")
!= NULL ? 0 : -EBUSY;
}
/*
* Configure/autoconfigure the port.
*/
static void pl010_config_port(struct uart_port *port, int flags)
{
if (flags & UART_CONFIG_TYPE) {
port->type = PORT_AMBA;
pl010_request_port(port);
}
}
/*
* verify the new serial_struct (for TIOCSSERIAL).
*/
static int pl010_verify_port(struct uart_port *port, struct serial_struct *ser)
{
int ret = 0;
if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMBA)
ret = -EINVAL;
if (ser->irq < 0 || ser->irq >= NR_IRQS)
ret = -EINVAL;
if (ser->baud_base < 9600)
ret = -EINVAL;
return ret;
}
static struct uart_ops amba_pl010_pops = {
.tx_empty = pl010_tx_empty,
.set_mctrl = pl010_set_mctrl,
.get_mctrl = pl010_get_mctrl,
.stop_tx = pl010_stop_tx,
.start_tx = pl010_start_tx,
.stop_rx = pl010_stop_rx,
.enable_ms = pl010_enable_ms,
.break_ctl = pl010_break_ctl,
.startup = pl010_startup,
.shutdown = pl010_shutdown,
.set_termios = pl010_set_termios,
.type = pl010_type,
.release_port = pl010_release_port,
.request_port = pl010_request_port,
.config_port = pl010_config_port,
.verify_port = pl010_verify_port,
};
static struct uart_amba_port *amba_ports[UART_NR];
#ifdef CONFIG_SERIAL_AMBA_PL010_CONSOLE
static void pl010_console_putchar(struct uart_port *port, int ch)
{
unsigned int status;
do {
status = readb(port->membase + UART01x_FR);
barrier();
} while (!UART_TX_READY(status));
writel(ch, port->membase + UART01x_DR);
}
static void
pl010_console_write(struct console *co, const char *s, unsigned int count)
{
struct uart_port *port = &amba_ports[co->index]->port;
unsigned int status, old_cr;
/*
* First save the CR then disable the interrupts
*/
old_cr = readb(port->membase + UART010_CR);
writel(UART01x_CR_UARTEN, port->membase + UART010_CR);
uart_console_write(port, s, count, pl010_console_putchar);
/*
* Finally, wait for transmitter to become empty
* and restore the TCR
*/
do {
status = readb(port->membase + UART01x_FR);
barrier();
} while (status & UART01x_FR_BUSY);
writel(old_cr, port->membase + UART010_CR);
}
static void __init
pl010_console_get_options(struct uart_port *port, int *baud,
int *parity, int *bits)
{
if (readb(port->membase + UART010_CR) & UART01x_CR_UARTEN) {
unsigned int lcr_h, quot;
lcr_h = readb(port->membase + UART010_LCRH);
*parity = 'n';
if (lcr_h & UART01x_LCRH_PEN) {
if (lcr_h & UART01x_LCRH_EPS)
*parity = 'e';
else
*parity = 'o';
}
if ((lcr_h & 0x60) == UART01x_LCRH_WLEN_7)
*bits = 7;
else
*bits = 8;
quot = readb(port->membase + UART010_LCRL) | readb(port->membase + UART010_LCRM) << 8;
*baud = port->uartclk / (16 * (quot + 1));
}
}
static int __init pl010_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.
*/
if (co->index >= UART_NR)
co->index = 0;
port = &amba_ports[co->index]->port;
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
pl010_console_get_options(port, &baud, &parity, &bits);
return uart_set_options(port, co, baud, parity, bits, flow);
}
static struct uart_driver amba_reg;
static struct console amba_console = {
.name = "ttyAM",
.write = pl010_console_write,
.device = uart_console_device,
.setup = pl010_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &amba_reg,
};
#define AMBA_CONSOLE &amba_console
#else
#define AMBA_CONSOLE NULL
#endif
static struct uart_driver amba_reg = {
.owner = THIS_MODULE,
.driver_name = "ttyAM",
.dev_name = "ttyAM",
.major = SERIAL_AMBA_MAJOR,
.minor = SERIAL_AMBA_MINOR,
.nr = UART_NR,
.cons = AMBA_CONSOLE,
};
static int pl010_probe(struct amba_device *dev, void *id)
{
struct uart_amba_port *port;
void __iomem *base;
int i, ret;
for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
if (amba_ports[i] == NULL)
break;
if (i == ARRAY_SIZE(amba_ports)) {
ret = -EBUSY;
goto out;
}
port = kzalloc(sizeof(struct uart_amba_port), GFP_KERNEL);
if (!port) {
ret = -ENOMEM;
goto out;
}
base = ioremap(dev->res.start, PAGE_SIZE);
if (!base) {
ret = -ENOMEM;
goto free;
}
port->port.dev = &dev->dev;
port->port.mapbase = dev->res.start;
port->port.membase = base;
port->port.iotype = UPIO_MEM;
port->port.irq = dev->irq[0];
port->port.uartclk = 14745600;
port->port.fifosize = 16;
port->port.ops = &amba_pl010_pops;
port->port.flags = UPF_BOOT_AUTOCONF;
port->port.line = i;
port->dev = dev;
port->data = dev->dev.platform_data;
amba_ports[i] = port;
amba_set_drvdata(dev, port);
ret = uart_add_one_port(&amba_reg, &port->port);
if (ret) {
amba_set_drvdata(dev, NULL);
amba_ports[i] = NULL;
iounmap(base);
free:
kfree(port);
}
out:
return ret;
}
static int pl010_remove(struct amba_device *dev)
{
struct uart_amba_port *port = amba_get_drvdata(dev);
int i;
amba_set_drvdata(dev, NULL);
uart_remove_one_port(&amba_reg, &port->port);
for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
if (amba_ports[i] == port)
amba_ports[i] = NULL;
iounmap(port->port.membase);
kfree(port);
return 0;
}
static int pl010_suspend(struct amba_device *dev, pm_message_t state)
{
struct uart_amba_port *uap = amba_get_drvdata(dev);
if (uap)
uart_suspend_port(&amba_reg, &uap->port);
return 0;
}
static int pl010_resume(struct amba_device *dev)
{
struct uart_amba_port *uap = amba_get_drvdata(dev);
if (uap)
uart_resume_port(&amba_reg, &uap->port);
return 0;
}
static struct amba_id pl010_ids[] __initdata = {
{
.id = 0x00041010,
.mask = 0x000fffff,
},
{ 0, 0 },
};
static struct amba_driver pl010_driver = {
.drv = {
.name = "uart-pl010",
},
.id_table = pl010_ids,
.probe = pl010_probe,
.remove = pl010_remove,
.suspend = pl010_suspend,
.resume = pl010_resume,
};
static int __init pl010_init(void)
{
int ret;
printk(KERN_INFO "Serial: AMBA driver $Revision: 1.41 $\n");
ret = uart_register_driver(&amba_reg);
if (ret == 0) {
ret = amba_driver_register(&pl010_driver);
if (ret)
uart_unregister_driver(&amba_reg);
}
return ret;
}
static void __exit pl010_exit(void)
{
amba_driver_unregister(&pl010_driver);
uart_unregister_driver(&amba_reg);
}
module_init(pl010_init);
module_exit(pl010_exit);
MODULE_AUTHOR("ARM Ltd/Deep Blue Solutions Ltd");
MODULE_DESCRIPTION("ARM AMBA serial port driver $Revision: 1.41 $");
MODULE_LICENSE("GPL");
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