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alistair23-linux/sound/oss/sh_dac_audio.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

332 lines
6.4 KiB
C
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/*
* sound/oss/sh_dac_audio.c
*
* SH DAC based sound :(
*
* Copyright (C) 2004,2005 Andriy Skulysh
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/linkage.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/sound.h>
#include <linux/soundcard.h>
#include <linux/interrupt.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/clock.h>
#include <asm/cpu/dac.h>
#include <asm/cpu/timer.h>
#include <asm/machvec.h>
#include <asm/hp6xx/hp6xx.h>
#include <asm/hd64461.h>
#define MODNAME "sh_dac_audio"
#define TMU_TOCR_INIT 0x00
#define TMU1_TCR_INIT 0x0020 /* Clock/4, rising edge; interrupt on */
#define TMU1_TSTR_INIT 0x02 /* Bit to turn on TMU1 */
#define BUFFER_SIZE 48000
static int rate;
static int empty;
static char *data_buffer, *buffer_begin, *buffer_end;
static int in_use, device_major;
static void dac_audio_start_timer(void)
{
u8 tstr;
tstr = ctrl_inb(TMU_TSTR);
tstr |= TMU1_TSTR_INIT;
ctrl_outb(tstr, TMU_TSTR);
}
static void dac_audio_stop_timer(void)
{
u8 tstr;
tstr = ctrl_inb(TMU_TSTR);
tstr &= ~TMU1_TSTR_INIT;
ctrl_outb(tstr, TMU_TSTR);
}
static void dac_audio_reset(void)
{
dac_audio_stop_timer();
buffer_begin = buffer_end = data_buffer;
empty = 1;
}
static void dac_audio_sync(void)
{
while (!empty)
schedule();
}
static void dac_audio_start(void)
{
if (mach_is_hp6xx()) {
u16 v = inw(HD64461_GPADR);
v &= ~HD64461_GPADR_SPEAKER;
outw(v, HD64461_GPADR);
}
sh_dac_enable(CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
ctrl_outw(TMU1_TCR_INIT, TMU1_TCR);
}
static void dac_audio_stop(void)
{
dac_audio_stop_timer();
if (mach_is_hp6xx()) {
u16 v = inw(HD64461_GPADR);
v |= HD64461_GPADR_SPEAKER;
outw(v, HD64461_GPADR);
}
sh_dac_output(0, CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
sh_dac_disable(CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
}
static void dac_audio_set_rate(void)
{
unsigned long interval;
struct clk *clk;
clk = clk_get("module_clk");
interval = (clk_get_rate(clk) / 4) / rate;
clk_put(clk);
ctrl_outl(interval, TMU1_TCOR);
ctrl_outl(interval, TMU1_TCNT);
}
static int dac_audio_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
int val;
switch (cmd) {
case OSS_GETVERSION:
return put_user(SOUND_VERSION, (int *)arg);
case SNDCTL_DSP_SYNC:
dac_audio_sync();
return 0;
case SNDCTL_DSP_RESET:
dac_audio_reset();
return 0;
case SNDCTL_DSP_GETFMTS:
return put_user(AFMT_U8, (int *)arg);
case SNDCTL_DSP_SETFMT:
return put_user(AFMT_U8, (int *)arg);
case SNDCTL_DSP_NONBLOCK:
file->f_flags |= O_NONBLOCK;
return 0;
case SNDCTL_DSP_GETCAPS:
return 0;
case SOUND_PCM_WRITE_RATE:
val = *(int *)arg;
if (val > 0) {
rate = val;
dac_audio_set_rate();
}
return put_user(rate, (int *)arg);
case SNDCTL_DSP_STEREO:
return put_user(0, (int *)arg);
case SOUND_PCM_WRITE_CHANNELS:
return put_user(1, (int *)arg);
case SNDCTL_DSP_SETDUPLEX:
return -EINVAL;
case SNDCTL_DSP_PROFILE:
return -EINVAL;
case SNDCTL_DSP_GETBLKSIZE:
return put_user(BUFFER_SIZE, (int *)arg);
case SNDCTL_DSP_SETFRAGMENT:
return 0;
default:
printk(KERN_ERR "sh_dac_audio: unimplemented ioctl=0x%x\n",
cmd);
return -EINVAL;
}
return -EINVAL;
}
static ssize_t dac_audio_write(struct file *file, const char *buf, size_t count,
loff_t * ppos)
{
int free;
int nbytes;
if (count < 0)
return -EINVAL;
if (!count) {
dac_audio_sync();
return 0;
}
free = buffer_begin - buffer_end;
if (free < 0)
free += BUFFER_SIZE;
if ((free == 0) && (empty))
free = BUFFER_SIZE;
if (count > free)
count = free;
if (buffer_begin > buffer_end) {
if (copy_from_user((void *)buffer_end, buf, count))
return -EFAULT;
buffer_end += count;
} else {
nbytes = data_buffer + BUFFER_SIZE - buffer_end;
if (nbytes > count) {
if (copy_from_user((void *)buffer_end, buf, count))
return -EFAULT;
buffer_end += count;
} else {
if (copy_from_user((void *)buffer_end, buf, nbytes))
return -EFAULT;
if (copy_from_user
((void *)data_buffer, buf + nbytes, count - nbytes))
return -EFAULT;
buffer_end = data_buffer + count - nbytes;
}
}
if (empty) {
empty = 0;
dac_audio_start_timer();
}
return count;
}
static ssize_t dac_audio_read(struct file *file, char *buf, size_t count,
loff_t * ppos)
{
return -EINVAL;
}
static int dac_audio_open(struct inode *inode, struct file *file)
{
if (file->f_mode & FMODE_READ)
return -ENODEV;
if (in_use)
return -EBUSY;
in_use = 1;
dac_audio_start();
return 0;
}
static int dac_audio_release(struct inode *inode, struct file *file)
{
dac_audio_sync();
dac_audio_stop();
in_use = 0;
return 0;
}
struct file_operations dac_audio_fops = {
.read = dac_audio_read,
.write = dac_audio_write,
.ioctl = dac_audio_ioctl,
.open = dac_audio_open,
.release = dac_audio_release,
};
static irqreturn_t timer1_interrupt(int irq, void *dev)
{
unsigned long timer_status;
timer_status = ctrl_inw(TMU1_TCR);
timer_status &= ~0x100;
ctrl_outw(timer_status, TMU1_TCR);
if (!empty) {
sh_dac_output(*buffer_begin, CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
buffer_begin++;
if (buffer_begin == data_buffer + BUFFER_SIZE)
buffer_begin = data_buffer;
if (buffer_begin == buffer_end) {
empty = 1;
dac_audio_stop_timer();
}
}
return IRQ_HANDLED;
}
static int __init dac_audio_init(void)
{
int retval;
if ((device_major = register_sound_dsp(&dac_audio_fops, -1)) < 0) {
printk(KERN_ERR "Cannot register dsp device");
return device_major;
}
in_use = 0;
data_buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
if (data_buffer == NULL)
return -ENOMEM;
dac_audio_reset();
rate = 8000;
dac_audio_set_rate();
retval =
request_irq(TIMER1_IRQ, timer1_interrupt, IRQF_DISABLED, MODNAME, 0);
if (retval < 0) {
printk(KERN_ERR "sh_dac_audio: IRQ %d request failed\n",
TIMER1_IRQ);
return retval;
}
return 0;
}
static void __exit dac_audio_exit(void)
{
free_irq(TIMER1_IRQ, 0);
unregister_sound_dsp(device_major);
kfree((void *)data_buffer);
}
module_init(dac_audio_init);
module_exit(dac_audio_exit);
MODULE_AUTHOR("Andriy Skulysh, askulysh@image.kiev.ua");
MODULE_DESCRIPTION("SH DAC sound driver");
MODULE_LICENSE("GPL");
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