WSL2-Linux-Kernel/drivers/char/dtlk.c

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16 KiB
C
Исходник Обычный вид История

/* -*- linux-c -*-
* dtlk.c - DoubleTalk PC driver for Linux
*
* Original author: Chris Pallotta <chris@allmedia.com>
* Current maintainer: Jim Van Zandt <jrv@vanzandt.mv.com>
*
* 2000-03-18 Jim Van Zandt: Fix polling.
* Eliminate dtlk_timer_active flag and separate dtlk_stop_timer
* function. Don't restart timer in dtlk_timer_tick. Restart timer
* in dtlk_poll after every poll. dtlk_poll returns mask (duh).
* Eliminate unused function dtlk_write_byte. Misc. code cleanups.
*/
/* This driver is for the DoubleTalk PC, a speech synthesizer
manufactured by RC Systems (http://www.rcsys.com/). It was written
based on documentation in their User's Manual file and Developer's
Tools disk.
The DoubleTalk PC contains four voice synthesizers: text-to-speech
(TTS), linear predictive coding (LPC), PCM/ADPCM, and CVSD. It
also has a tone generator. Output data for LPC are written to the
LPC port, and output data for the other modes are written to the
TTS port.
Two kinds of data can be read from the DoubleTalk: status
information (in response to the "\001?" interrogation command) is
read from the TTS port, and index markers (which mark the progress
of the speech) are read from the LPC port. Not all models of the
DoubleTalk PC implement index markers. Both the TTS and LPC ports
can also display status flags.
The DoubleTalk PC generates no interrupts.
These characteristics are mapped into the Unix stream I/O model as
follows:
"write" sends bytes to the TTS port. It is the responsibility of
the user program to switch modes among TTS, PCM/ADPCM, and CVSD.
This driver was written for use with the text-to-speech
synthesizer. If LPC output is needed some day, other minor device
numbers can be used to select among output modes.
"read" gets index markers from the LPC port. If the device does
not implement index markers, the read will fail with error EINVAL.
Status information is available using the DTLK_INTERROGATE ioctl.
*/
#include <linux/module.h>
#define KERNEL
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/errno.h> /* for -EBUSY */
#include <linux/ioport.h> /* for request_region */
#include <linux/delay.h> /* for loops_per_jiffy */
#include <linux/sched.h>
#include <linux/mutex.h>
#include <asm/io.h> /* for inb_p, outb_p, inb, outb, etc. */
#include <asm/uaccess.h> /* for get_user, etc. */
#include <linux/wait.h> /* for wait_queue */
#include <linux/init.h> /* for __init, module_{init,exit} */
#include <linux/poll.h> /* for POLLIN, etc. */
#include <linux/dtlk.h> /* local header file for DoubleTalk values */
#ifdef TRACING
#define TRACE_TEXT(str) printk(str);
#define TRACE_RET printk(")")
#else /* !TRACING */
#define TRACE_TEXT(str) ((void) 0)
#define TRACE_RET ((void) 0)
#endif /* TRACING */
static DEFINE_MUTEX(dtlk_mutex);
static void dtlk_timer_tick(unsigned long data);
static int dtlk_major;
static int dtlk_port_lpc;
static int dtlk_port_tts;
static int dtlk_busy;
static int dtlk_has_indexing;
static unsigned int dtlk_portlist[] =
{0x25e, 0x29e, 0x2de, 0x31e, 0x35e, 0x39e, 0};
static wait_queue_head_t dtlk_process_list;
static DEFINE_TIMER(dtlk_timer, dtlk_timer_tick, 0, 0);
/* prototypes for file_operations struct */
static ssize_t dtlk_read(struct file *, char __user *,
size_t nbytes, loff_t * ppos);
static ssize_t dtlk_write(struct file *, const char __user *,
size_t nbytes, loff_t * ppos);
static unsigned int dtlk_poll(struct file *, poll_table *);
static int dtlk_open(struct inode *, struct file *);
static int dtlk_release(struct inode *, struct file *);
static long dtlk_ioctl(struct file *file,
unsigned int cmd, unsigned long arg);
static const struct file_operations dtlk_fops =
{
.owner = THIS_MODULE,
.read = dtlk_read,
.write = dtlk_write,
.poll = dtlk_poll,
.unlocked_ioctl = dtlk_ioctl,
.open = dtlk_open,
.release = dtlk_release,
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 20:52:59 +04:00
.llseek = no_llseek,
};
/* local prototypes */
static int dtlk_dev_probe(void);
static struct dtlk_settings *dtlk_interrogate(void);
static int dtlk_readable(void);
static char dtlk_read_lpc(void);
static char dtlk_read_tts(void);
static int dtlk_writeable(void);
static char dtlk_write_bytes(const char *buf, int n);
static char dtlk_write_tts(char);
/*
static void dtlk_handle_error(char, char, unsigned int);
*/
static ssize_t dtlk_read(struct file *file, char __user *buf,
size_t count, loff_t * ppos)
{
unsigned int minor = iminor(file_inode(file));
char ch;
int i = 0, retries;
TRACE_TEXT("(dtlk_read");
/* printk("DoubleTalk PC - dtlk_read()\n"); */
if (minor != DTLK_MINOR || !dtlk_has_indexing)
return -EINVAL;
for (retries = 0; retries < loops_per_jiffy; retries++) {
while (i < count && dtlk_readable()) {
ch = dtlk_read_lpc();
/* printk("dtlk_read() reads 0x%02x\n", ch); */
if (put_user(ch, buf++))
return -EFAULT;
i++;
}
if (i)
return i;
if (file->f_flags & O_NONBLOCK)
break;
msleep_interruptible(100);
}
if (retries == loops_per_jiffy)
printk(KERN_ERR "dtlk_read times out\n");
TRACE_RET;
return -EAGAIN;
}
static ssize_t dtlk_write(struct file *file, const char __user *buf,
size_t count, loff_t * ppos)
{
int i = 0, retries = 0, ch;
TRACE_TEXT("(dtlk_write");
#ifdef TRACING
printk(" \"");
{
int i, ch;
for (i = 0; i < count; i++) {
if (get_user(ch, buf + i))
return -EFAULT;
if (' ' <= ch && ch <= '~')
printk("%c", ch);
else
printk("\\%03o", ch);
}
printk("\"");
}
#endif
if (iminor(file_inode(file)) != DTLK_MINOR)
return -EINVAL;
while (1) {
while (i < count && !get_user(ch, buf) &&
(ch == DTLK_CLEAR || dtlk_writeable())) {
dtlk_write_tts(ch);
buf++;
i++;
if (i % 5 == 0)
/* We yield our time until scheduled
again. This reduces the transfer
rate to 500 bytes/sec, but that's
still enough to keep up with the
speech synthesizer. */
msleep_interruptible(1);
else {
/* the RDY bit goes zero 2-3 usec
after writing, and goes 1 again
180-190 usec later. Here, we wait
up to 250 usec for the RDY bit to
go nonzero. */
for (retries = 0;
retries < loops_per_jiffy / (4000/HZ);
retries++)
if (inb_p(dtlk_port_tts) &
TTS_WRITABLE)
break;
}
retries = 0;
}
if (i == count)
return i;
if (file->f_flags & O_NONBLOCK)
break;
msleep_interruptible(1);
if (++retries > 10 * HZ) { /* wait no more than 10 sec
from last write */
printk("dtlk: write timeout. "
"inb_p(dtlk_port_tts) = 0x%02x\n",
inb_p(dtlk_port_tts));
TRACE_RET;
return -EBUSY;
}
}
TRACE_RET;
return -EAGAIN;
}
static unsigned int dtlk_poll(struct file *file, poll_table * wait)
{
int mask = 0;
unsigned long expires;
TRACE_TEXT(" dtlk_poll");
/*
static long int j;
printk(".");
printk("<%ld>", jiffies-j);
j=jiffies;
*/
poll_wait(file, &dtlk_process_list, wait);
if (dtlk_has_indexing && dtlk_readable()) {
del_timer(&dtlk_timer);
mask = POLLIN | POLLRDNORM;
}
if (dtlk_writeable()) {
del_timer(&dtlk_timer);
mask |= POLLOUT | POLLWRNORM;
}
/* there are no exception conditions */
/* There won't be any interrupts, so we set a timer instead. */
expires = jiffies + 3*HZ / 100;
mod_timer(&dtlk_timer, expires);
return mask;
}
static void dtlk_timer_tick(unsigned long data)
{
TRACE_TEXT(" dtlk_timer_tick");
wake_up_interruptible(&dtlk_process_list);
}
static long dtlk_ioctl(struct file *file,
unsigned int cmd,
unsigned long arg)
{
char __user *argp = (char __user *)arg;
struct dtlk_settings *sp;
char portval;
TRACE_TEXT(" dtlk_ioctl");
switch (cmd) {
case DTLK_INTERROGATE:
mutex_lock(&dtlk_mutex);
sp = dtlk_interrogate();
mutex_unlock(&dtlk_mutex);
if (copy_to_user(argp, sp, sizeof(struct dtlk_settings)))
return -EINVAL;
return 0;
case DTLK_STATUS:
portval = inb_p(dtlk_port_tts);
return put_user(portval, argp);
default:
return -EINVAL;
}
}
/* Note that nobody ever sets dtlk_busy... */
static int dtlk_open(struct inode *inode, struct file *file)
{
TRACE_TEXT("(dtlk_open");
nonseekable_open(inode, file);
switch (iminor(inode)) {
case DTLK_MINOR:
if (dtlk_busy)
return -EBUSY;
return nonseekable_open(inode, file);
default:
return -ENXIO;
}
}
static int dtlk_release(struct inode *inode, struct file *file)
{
TRACE_TEXT("(dtlk_release");
switch (iminor(inode)) {
case DTLK_MINOR:
break;
default:
break;
}
TRACE_RET;
del_timer_sync(&dtlk_timer);
return 0;
}
static int __init dtlk_init(void)
{
int err;
dtlk_port_lpc = 0;
dtlk_port_tts = 0;
dtlk_busy = 0;
dtlk_major = register_chrdev(0, "dtlk", &dtlk_fops);
if (dtlk_major < 0) {
printk(KERN_ERR "DoubleTalk PC - cannot register device\n");
return dtlk_major;
}
err = dtlk_dev_probe();
if (err) {
unregister_chrdev(dtlk_major, "dtlk");
return err;
}
printk(", MAJOR %d\n", dtlk_major);
init_waitqueue_head(&dtlk_process_list);
return 0;
}
static void __exit dtlk_cleanup (void)
{
dtlk_write_bytes("goodbye", 8);
msleep_interruptible(500); /* nap 0.50 sec but
could be awakened
earlier by
signals... */
dtlk_write_tts(DTLK_CLEAR);
unregister_chrdev(dtlk_major, "dtlk");
release_region(dtlk_port_lpc, DTLK_IO_EXTENT);
}
module_init(dtlk_init);
module_exit(dtlk_cleanup);
/* ------------------------------------------------------------------------ */
static int dtlk_readable(void)
{
#ifdef TRACING
printk(" dtlk_readable=%u@%u", inb_p(dtlk_port_lpc) != 0x7f, jiffies);
#endif
return inb_p(dtlk_port_lpc) != 0x7f;
}
static int dtlk_writeable(void)
{
/* TRACE_TEXT(" dtlk_writeable"); */
#ifdef TRACINGMORE
printk(" dtlk_writeable=%u", (inb_p(dtlk_port_tts) & TTS_WRITABLE)!=0);
#endif
return inb_p(dtlk_port_tts) & TTS_WRITABLE;
}
static int __init dtlk_dev_probe(void)
{
unsigned int testval = 0;
int i = 0;
struct dtlk_settings *sp;
if (dtlk_port_lpc | dtlk_port_tts)
return -EBUSY;
for (i = 0; dtlk_portlist[i]; i++) {
#if 0
printk("DoubleTalk PC - Port %03x = %04x\n",
dtlk_portlist[i], (testval = inw_p(dtlk_portlist[i])));
#endif
if (!request_region(dtlk_portlist[i], DTLK_IO_EXTENT,
"dtlk"))
continue;
testval = inw_p(dtlk_portlist[i]);
if ((testval &= 0xfbff) == 0x107f) {
dtlk_port_lpc = dtlk_portlist[i];
dtlk_port_tts = dtlk_port_lpc + 1;
sp = dtlk_interrogate();
printk("DoubleTalk PC at %03x-%03x, "
"ROM version %s, serial number %u",
dtlk_portlist[i], dtlk_portlist[i] +
DTLK_IO_EXTENT - 1,
sp->rom_version, sp->serial_number);
/* put LPC port into known state, so
dtlk_readable() gives valid result */
outb_p(0xff, dtlk_port_lpc);
/* INIT string and index marker */
dtlk_write_bytes("\036\1@\0\0012I\r", 8);
/* posting an index takes 18 msec. Here, we
wait up to 100 msec to see whether it
appears. */
msleep_interruptible(100);
dtlk_has_indexing = dtlk_readable();
#ifdef TRACING
printk(", indexing %d\n", dtlk_has_indexing);
#endif
#ifdef INSCOPE
{
/* This macro records ten samples read from the LPC port, for later display */
#define LOOK \
for (i = 0; i < 10; i++) \
{ \
buffer[b++] = inb_p(dtlk_port_lpc); \
__delay(loops_per_jiffy/(1000000/HZ)); \
}
char buffer[1000];
int b = 0, i, j;
LOOK
outb_p(0xff, dtlk_port_lpc);
buffer[b++] = 0;
LOOK
dtlk_write_bytes("\0012I\r", 4);
buffer[b++] = 0;
__delay(50 * loops_per_jiffy / (1000/HZ));
outb_p(0xff, dtlk_port_lpc);
buffer[b++] = 0;
LOOK
printk("\n");
for (j = 0; j < b; j++)
printk(" %02x", buffer[j]);
printk("\n");
}
#endif /* INSCOPE */
#ifdef OUTSCOPE
{
/* This macro records ten samples read from the TTS port, for later display */
#define LOOK \
for (i = 0; i < 10; i++) \
{ \
buffer[b++] = inb_p(dtlk_port_tts); \
__delay(loops_per_jiffy/(1000000/HZ)); /* 1 us */ \
}
char buffer[1000];
int b = 0, i, j;
mdelay(10); /* 10 ms */
LOOK
outb_p(0x03, dtlk_port_tts);
buffer[b++] = 0;
LOOK
LOOK
printk("\n");
for (j = 0; j < b; j++)
printk(" %02x", buffer[j]);
printk("\n");
}
#endif /* OUTSCOPE */
dtlk_write_bytes("Double Talk found", 18);
return 0;
}
release_region(dtlk_portlist[i], DTLK_IO_EXTENT);
}
printk(KERN_INFO "DoubleTalk PC - not found\n");
return -ENODEV;
}
/*
static void dtlk_handle_error(char op, char rc, unsigned int minor)
{
printk(KERN_INFO"\nDoubleTalk PC - MINOR: %d, OPCODE: %d, ERROR: %d\n",
minor, op, rc);
return;
}
*/
/* interrogate the DoubleTalk PC and return its settings */
static struct dtlk_settings *dtlk_interrogate(void)
{
unsigned char *t;
static char buf[sizeof(struct dtlk_settings) + 1];
int total, i;
static struct dtlk_settings status;
TRACE_TEXT("(dtlk_interrogate");
dtlk_write_bytes("\030\001?", 3);
for (total = 0, i = 0; i < 50; i++) {
buf[total] = dtlk_read_tts();
if (total > 2 && buf[total] == 0x7f)
break;
if (total < sizeof(struct dtlk_settings))
total++;
}
/*
if (i==50) printk("interrogate() read overrun\n");
for (i=0; i<sizeof(buf); i++)
printk(" %02x", buf[i]);
printk("\n");
*/
t = buf;
status.serial_number = t[0] + t[1] * 256; /* serial number is
little endian */
t += 2;
i = 0;
while (*t != '\r') {
status.rom_version[i] = *t;
if (i < sizeof(status.rom_version) - 1)
i++;
t++;
}
status.rom_version[i] = 0;
t++;
status.mode = *t++;
status.punc_level = *t++;
status.formant_freq = *t++;
status.pitch = *t++;
status.speed = *t++;
status.volume = *t++;
status.tone = *t++;
status.expression = *t++;
status.ext_dict_loaded = *t++;
status.ext_dict_status = *t++;
status.free_ram = *t++;
status.articulation = *t++;
status.reverb = *t++;
status.eob = *t++;
status.has_indexing = dtlk_has_indexing;
TRACE_RET;
return &status;
}
static char dtlk_read_tts(void)
{
int portval, retries = 0;
char ch;
TRACE_TEXT("(dtlk_read_tts");
/* verify DT is ready, read char, wait for ACK */
do {
portval = inb_p(dtlk_port_tts);
} while ((portval & TTS_READABLE) == 0 &&
retries++ < DTLK_MAX_RETRIES);
if (retries > DTLK_MAX_RETRIES)
printk(KERN_ERR "dtlk_read_tts() timeout\n");
ch = inb_p(dtlk_port_tts); /* input from TTS port */
ch &= 0x7f;
outb_p(ch, dtlk_port_tts);
retries = 0;
do {
portval = inb_p(dtlk_port_tts);
} while ((portval & TTS_READABLE) != 0 &&
retries++ < DTLK_MAX_RETRIES);
if (retries > DTLK_MAX_RETRIES)
printk(KERN_ERR "dtlk_read_tts() timeout\n");
TRACE_RET;
return ch;
}
static char dtlk_read_lpc(void)
{
int retries = 0;
char ch;
TRACE_TEXT("(dtlk_read_lpc");
/* no need to test -- this is only called when the port is readable */
ch = inb_p(dtlk_port_lpc); /* input from LPC port */
outb_p(0xff, dtlk_port_lpc);
/* acknowledging a read takes 3-4
usec. Here, we wait up to 20 usec
for the acknowledgement */
retries = (loops_per_jiffy * 20) / (1000000/HZ);
while (inb_p(dtlk_port_lpc) != 0x7f && --retries > 0);
if (retries == 0)
printk(KERN_ERR "dtlk_read_lpc() timeout\n");
TRACE_RET;
return ch;
}
/* write n bytes to tts port */
static char dtlk_write_bytes(const char *buf, int n)
{
char val = 0;
/* printk("dtlk_write_bytes(\"%-*s\", %d)\n", n, buf, n); */
TRACE_TEXT("(dtlk_write_bytes");
while (n-- > 0)
val = dtlk_write_tts(*buf++);
TRACE_RET;
return val;
}
static char dtlk_write_tts(char ch)
{
int retries = 0;
#ifdef TRACINGMORE
printk(" dtlk_write_tts(");
if (' ' <= ch && ch <= '~')
printk("'%c'", ch);
else
printk("0x%02x", ch);
#endif
if (ch != DTLK_CLEAR) /* no flow control for CLEAR command */
while ((inb_p(dtlk_port_tts) & TTS_WRITABLE) == 0 &&
retries++ < DTLK_MAX_RETRIES) /* DT ready? */
;
if (retries > DTLK_MAX_RETRIES)
printk(KERN_ERR "dtlk_write_tts() timeout\n");
outb_p(ch, dtlk_port_tts); /* output to TTS port */
/* the RDY bit goes zero 2-3 usec after writing, and goes
1 again 180-190 usec later. Here, we wait up to 10
usec for the RDY bit to go zero. */
for (retries = 0; retries < loops_per_jiffy / (100000/HZ); retries++)
if ((inb_p(dtlk_port_tts) & TTS_WRITABLE) == 0)
break;
#ifdef TRACINGMORE
printk(")\n");
#endif
return 0;
}
MODULE_LICENSE("GPL");