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DEFINITIONS
This source file includes following definitions.
- short_incr_bp
- short_open
- short_release
- do_short_read
- short_read
- do_short_write
- short_write
- short_poll
- short_i_read
- short_i_write
- short_interrupt
- short_incr_tv
- short_do_tasklet
- short_wq_interrupt
- short_tl_interrupt
- short_sh_interrupt
- short_kernelprobe
- short_probing
- short_selfprobe
- short_init
- short_cleanup
/*
* short.c -- Simple Hardware Operations and Raw Tests
* short.c -- also a brief example of interrupt handling ("short int")
*
* Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
* Copyright (C) 2001 O'Reilly & Associates
*
* The source code in this file can be freely used, adapted,
* and redistributed in source or binary form, so long as an
* acknowledgment appears in derived source files. The citation
* should list that the code comes from the book "Linux Device
* Drivers" by Alessandro Rubini and Jonathan Corbet, published
* by O'Reilly & Associates. No warranty is attached;
* we cannot take responsibility for errors or fitness for use.
*
* $Id: short.c,v 1.16 2004/10/29 16:45:40 corbet Exp $
*/
/*
* FIXME: this driver is not safe with concurrent readers or
* writers.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/kernel.h> /* printk() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/delay.h> /* udelay */
#include <linux/kdev_t.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <asm/io.h>
#define SHORT_NR_PORTS 8 /* use 8 ports by default */
/*
* all of the parameters have no "short_" prefix, to save typing when
* specifying them at load time
*/
static int major = 0; /* dynamic by default */
module_param(major, int, 0);
static int use_mem = 0; /* default is I/O-mapped */
module_param(use_mem, int, 0);
/* default is the first printer port on PC's. "short_base" is there too
because it's what we want to use in the code */
static unsigned long base = 0x378;
unsigned long short_base = 0;
module_param(base, long, 0);
/* The interrupt line is undefined by default. "short_irq" is as above */
static int irq = -1;
volatile int short_irq = -1;
module_param(irq, int, 0);
static int probe = 0; /* select at load time how to probe irq line */
module_param(probe, int, 0);
static int wq = 0; /* select at load time whether a workqueue is used */
module_param(wq, int, 0);
static int tasklet = 0; /* select whether a tasklet is used */
module_param(tasklet, int, 0);
static int share = 0; /* select at load time whether install a shared irq */
module_param(share, int, 0);
MODULE_AUTHOR ("Alessandro Rubini");
MODULE_LICENSE("Dual BSD/GPL");
unsigned long short_buffer = 0;
unsigned long volatile short_head;
volatile unsigned long short_tail;
DECLARE_WAIT_QUEUE_HEAD(short_queue);
/* Set up our tasklet if we're doing that. */
void short_do_tasklet(unsigned long);
DECLARE_TASKLET(short_tasklet, short_do_tasklet, 0);
/*
* Atomicly increment an index into short_buffer
*/
static inline void short_incr_bp(volatile unsigned long *index, int delta)
{
unsigned long new = *index + delta;
barrier(); /* Don't optimize these two together */
*index = (new >= (short_buffer + PAGE_SIZE)) ? short_buffer : new;
}
/*
* The devices with low minor numbers write/read burst of data to/from
* specific I/O ports (by default the parallel ones).
*
* The device with 128 as minor number returns ascii strings telling
* when interrupts have been received. Writing to the device toggles
* 00/FF on the parallel data lines. If there is a loopback wire, this
* generates interrupts.
*/
int short_open (struct inode *inode, struct file *filp)
{
extern struct file_operations short_i_fops;
if (iminor (inode) & 0x80)
filp->f_op = &short_i_fops; /* the interrupt-driven node */
return 0;
}
int short_release (struct inode *inode, struct file *filp)
{
return 0;
}
/* first, the port-oriented device */
enum short_modes {SHORT_DEFAULT=0, SHORT_PAUSE, SHORT_STRING, SHORT_MEMORY};
ssize_t do_short_read (struct inode *inode, struct file *filp, char __user *buf,
size_t count, loff_t *f_pos)
{
int retval = count, minor = iminor (inode);
unsigned long port = short_base + (minor&0x0f);
void *address = (void *) short_base + (minor&0x0f);
int mode = (minor&0x70) >> 4;
unsigned char *kbuf = kmalloc(count, GFP_KERNEL), *ptr;
if (!kbuf)
return -ENOMEM;
ptr = kbuf;
if (use_mem)
mode = SHORT_MEMORY;
switch(mode) {
case SHORT_STRING:
insb(port, ptr, count);
rmb();
break;
case SHORT_DEFAULT:
while (count--) {
*(ptr++) = inb(port);
rmb();
}
break;
case SHORT_MEMORY:
while (count--) {
*ptr++ = ioread8(address);
rmb();
}
break;
case SHORT_PAUSE:
while (count--) {
*(ptr++) = inb_p(port);
rmb();
}
break;
default: /* no more modes defined by now */
retval = -EINVAL;
break;
}
if ((retval > 0) && copy_to_user(buf, kbuf, retval))
retval = -EFAULT;
kfree(kbuf);
return retval;
}
/*
* Version-specific methods for the fops structure. FIXME don't need anymore.
*/
ssize_t short_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
return do_short_read(filp->f_dentry->d_inode, filp, buf, count, f_pos);
}
ssize_t do_short_write (struct inode *inode, struct file *filp, const char __user *buf,
size_t count, loff_t *f_pos)
{
int retval = count, minor = iminor(inode);
unsigned long port = short_base + (minor&0x0f);
void *address = (void *) short_base + (minor&0x0f);
int mode = (minor&0x70) >> 4;
unsigned char *kbuf = kmalloc(count, GFP_KERNEL), *ptr;
if (!kbuf)
return -ENOMEM;
if (copy_from_user(kbuf, buf, count))
return -EFAULT;
ptr = kbuf;
if (use_mem)
mode = SHORT_MEMORY;
switch(mode) {
case SHORT_PAUSE:
while (count--) {
outb_p(*(ptr++), port);
wmb();
}
break;
case SHORT_STRING:
outsb(port, ptr, count);
wmb();
break;
case SHORT_DEFAULT:
while (count--) {
outb(*(ptr++), port);
wmb();
}
break;
case SHORT_MEMORY:
while (count--) {
iowrite8(*ptr++, address);
wmb();
}
break;
default: /* no more modes defined by now */
retval = -EINVAL;
break;
}
kfree(kbuf);
return retval;
}
ssize_t short_write(struct file *filp, const char __user *buf, size_t count,
loff_t *f_pos)
{
return do_short_write(filp->f_dentry->d_inode, filp, buf, count, f_pos);
}
unsigned int short_poll(struct file *filp, poll_table *wait)
{
return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM;
}
struct file_operations short_fops = {
.owner = THIS_MODULE,
.read = short_read,
.write = short_write,
.poll = short_poll,
.open = short_open,
.release = short_release,
};
/* then, the interrupt-related device */
ssize_t short_i_read (struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
int count0;
DEFINE_WAIT(wait);
while (short_head == short_tail) {
prepare_to_wait(&short_queue, &wait, TASK_INTERRUPTIBLE);
if (short_head == short_tail)
schedule();
finish_wait(&short_queue, &wait);
if (signal_pending (current)) /* a signal arrived */
return -ERESTARTSYS; /* tell the fs layer to handle it */
}
/* count0 is the number of readable data bytes */
count0 = short_head - short_tail;
if (count0 < 0) /* wrapped */
count0 = short_buffer + PAGE_SIZE - short_tail;
if (count0 < count) count = count0;
if (copy_to_user(buf, (char *)short_tail, count))
return -EFAULT;
short_incr_bp (&short_tail, count);
return count;
}
ssize_t short_i_write (struct file *filp, const char __user *buf, size_t count,
loff_t *f_pos)
{
int written = 0, odd = *f_pos & 1;
unsigned long port = short_base; /* output to the parallel data latch */
void *address = (void *) short_base;
if (use_mem) {
while (written < count)
iowrite8(0xff * ((++written + odd) & 1), address);
} else {
while (written < count)
outb(0xff * ((++written + odd) & 1), port);
}
*f_pos += count;
return written;
}
struct file_operations short_i_fops = {
.owner = THIS_MODULE,
.read = short_i_read,
.write = short_i_write,
.open = short_open,
.release = short_release,
};
irqreturn_t short_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
struct timeval tv;
int written;
do_gettimeofday(&tv);
/* Write a 16 byte record. Assume PAGE_SIZE is a multiple of 16 */
written = sprintf((char *)short_head,"%08u.%06u\n",
(int)(tv.tv_sec % 100000000), (int)(tv.tv_usec));
BUG_ON(written != 16);
short_incr_bp(&short_head, written);
wake_up_interruptible(&short_queue); /* awake any reading process */
return IRQ_HANDLED;
}
/*
* The following two functions are equivalent to the previous one,
* but split in top and bottom half. First, a few needed variables
*/
#define NR_TIMEVAL 512 /* length of the array of time values */
struct timeval tv_data[NR_TIMEVAL]; /* too lazy to allocate it */
volatile struct timeval *tv_head=tv_data;
volatile struct timeval *tv_tail=tv_data;
static struct work_struct short_wq;
int short_wq_count = 0;
/*
* Increment a circular buffer pointer in a way that nobody sees
* an intermediate value.
*/
static inline void short_incr_tv(volatile struct timeval **tvp)
{
if (*tvp == (tv_data + NR_TIMEVAL - 1))
*tvp = tv_data; /* Wrap */
else
(*tvp)++;
}
void short_do_tasklet (unsigned long unused)
{
int savecount = short_wq_count, written;
short_wq_count = 0; /* we have already been removed from the queue */
/*
* The bottom half reads the tv array, filled by the top half,
* and prints it to the circular text buffer, which is then consumed
* by reading processes
*/
/* First write the number of interrupts that occurred before this bh */
written = sprintf((char *)short_head,"bh after %6i\n",savecount);
short_incr_bp(&short_head, written);
/*
* Then, write the time values. Write exactly 16 bytes at a time,
* so it aligns with PAGE_SIZE
*/
do {
written = sprintf((char *)short_head,"%08u.%06u\n",
(int)(tv_tail->tv_sec % 100000000),
(int)(tv_tail->tv_usec));
short_incr_bp(&short_head, written);
short_incr_tv(&tv_tail);
} while (tv_tail != tv_head);
wake_up_interruptible(&short_queue); /* awake any reading process */
}
irqreturn_t short_wq_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
/* Grab the current time information. */
do_gettimeofday((struct timeval *) tv_head);
short_incr_tv(&tv_head);
/* Queue the bh. Don't worry about multiple enqueueing */
schedule_work(&short_wq);
short_wq_count++; /* record that an interrupt arrived */
return IRQ_HANDLED;
}
/*
* Tasklet top half
*/
irqreturn_t short_tl_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
do_gettimeofday((struct timeval *) tv_head); /* cast to stop 'volatile' warning */
short_incr_tv(&tv_head);
tasklet_schedule(&short_tasklet);
short_wq_count++; /* record that an interrupt arrived */
return IRQ_HANDLED;
}
irqreturn_t short_sh_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
int value, written;
struct timeval tv;
/* If it wasn't short, return immediately */
value = inb(short_base);
if (!(value & 0x80))
return IRQ_NONE;
/* clear the interrupting bit */
outb(value & 0x7F, short_base);
/* the rest is unchanged */
do_gettimeofday(&tv);
written = sprintf((char *)short_head,"%08u.%06u\n",
(int)(tv.tv_sec % 100000000), (int)(tv.tv_usec));
short_incr_bp(&short_head, written);
wake_up_interruptible(&short_queue); /* awake any reading process */
return IRQ_HANDLED;
}
void short_kernelprobe(void)
{
int count = 0;
do {
unsigned long mask;
mask = probe_irq_on();
outb_p(0x10,short_base+2); /* enable reporting */
outb_p(0x00,short_base); /* clear the bit */
outb_p(0xFF,short_base); /* set the bit: interrupt! */
outb_p(0x00,short_base+2); /* disable reporting */
udelay(5); /* give it some time */
short_irq = probe_irq_off(mask);
if (short_irq == 0) { /* none of them? */
printk(KERN_INFO "short: no irq reported by probe\n");
short_irq = -1;
}
/*
* if more than one line has been activated, the result is
* negative. We should service the interrupt (no need for lpt port)
* and loop over again. Loop at most five times, then give up
*/
} while (short_irq < 0 && count++ < 5);
if (short_irq < 0)
printk("short: probe failed %i times, giving up\n", count);
}
irqreturn_t short_probing(int irq, void *dev_id, struct pt_regs *regs)
{
if (short_irq == 0) short_irq = irq; /* found */
if (short_irq != irq) short_irq = -irq; /* ambiguous */
return IRQ_HANDLED;
}
void short_selfprobe(void)
{
int trials[] = {3, 5, 7, 9, 0};
int tried[] = {0, 0, 0, 0, 0};
int i, count = 0;
/*
* install the probing handler for all possible lines. Remember
* the result (0 for success, or -EBUSY) in order to only free
* what has been acquired
*/
for (i = 0; trials[i]; i++)
tried[i] = request_irq(trials[i], short_probing,
SA_INTERRUPT, "short probe", NULL);
do {
short_irq = 0; /* none got, yet */
outb_p(0x10,short_base+2); /* enable */
outb_p(0x00,short_base);
outb_p(0xFF,short_base); /* toggle the bit */
outb_p(0x00,short_base+2); /* disable */
udelay(5); /* give it some time */
/* the value has been set by the handler */
if (short_irq == 0) { /* none of them? */
printk(KERN_INFO "short: no irq reported by probe\n");
}
/*
* If more than one line has been activated, the result is
* negative. We should service the interrupt (but the lpt port
* doesn't need it) and loop over again. Do it at most 5 times
*/
} while (short_irq <=0 && count++ < 5);
/* end of loop, uninstall the handler */
for (i = 0; trials[i]; i++)
if (tried[i] == 0)
free_irq(trials[i], NULL);
if (short_irq < 0)
printk("short: probe failed %i times, giving up\n", count);
}
/* Finally, init and cleanup */
int short_init(void)
{
int result;
/*
* first, sort out the base/short_base ambiguity: we'd better
* use short_base in the code, for clarity, but allow setting
* just "base" at load time. Same for "irq".
*/
short_base = base;
short_irq = irq;
/* Get our needed resources. */
if (!use_mem) {
if (! request_region(short_base, SHORT_NR_PORTS, "short")) {
printk(KERN_INFO "short: can't get I/O port address 0x%lx\n",
short_base);
return -ENODEV;
}
} else {
if (! request_mem_region(short_base, SHORT_NR_PORTS, "short")) {
printk(KERN_INFO "short: can't get I/O mem address 0x%lx\n",
short_base);
return -ENODEV;
}
/* also, ioremap it */
short_base = (unsigned long) ioremap(short_base, SHORT_NR_PORTS);
/* Hmm... we should check the return value */
}
/* Here we register our device - should not fail thereafter */
result = register_chrdev(major, "short", &short_fops);
if (result < 0) {
printk(KERN_INFO "short: can't get major number\n");
release_region(short_base,SHORT_NR_PORTS); /* FIXME - use-mem case? */
return result;
}
if (major == 0) major = result; /* dynamic */
short_buffer = __get_free_pages(GFP_KERNEL,0); /* never fails */ /* FIXME */
short_head = short_tail = short_buffer;
/*
* Fill the workqueue structure, used for the bottom half handler.
* The cast is there to prevent warnings about the type of the
* (unused) argument.
*/
/* this line is in short_init() */
INIT_WORK(&short_wq, (void (*)(void *)) short_do_tasklet, NULL);
/*
* Now we deal with the interrupt: either kernel-based
* autodetection, DIY detection or default number
*/
if (short_irq < 0 && probe == 1)
short_kernelprobe();
if (short_irq < 0 && probe == 2)
short_selfprobe();
if (short_irq < 0) /* not yet specified: force the default on */
switch(short_base) {
case 0x378: short_irq = 7; break;
case 0x278: short_irq = 2; break;
case 0x3bc: short_irq = 5; break;
}
/*
* If shared has been specified, installed the shared handler
* instead of the normal one. Do it first, before a -EBUSY will
* force short_irq to -1.
*/
if (short_irq >= 0 && share > 0) {
result = request_irq(short_irq, short_sh_interrupt,
SA_SHIRQ | SA_INTERRUPT,"short",
short_sh_interrupt);
if (result) {
printk(KERN_INFO "short: can't get assigned irq %i\n", short_irq);
short_irq = -1;
}
else { /* actually enable it -- assume this *is* a parallel port */
outb(0x10, short_base+2);
}
return 0; /* the rest of the function only installs handlers */
}
if (short_irq >= 0) {
result = request_irq(short_irq, short_interrupt,
SA_INTERRUPT, "short", NULL);
if (result) {
printk(KERN_INFO "short: can't get assigned irq %i\n",
short_irq);
short_irq = -1;
}
else { /* actually enable it -- assume this *is* a parallel port */
outb(0x10,short_base+2);
}
}
/*
* Ok, now change the interrupt handler if using top/bottom halves
* has been requested
*/
if (short_irq >= 0 && (wq + tasklet) > 0) {
free_irq(short_irq,NULL);
result = request_irq(short_irq,
tasklet ? short_tl_interrupt :
short_wq_interrupt,
SA_INTERRUPT,"short-bh", NULL);
if (result) {
printk(KERN_INFO "short-bh: can't get assigned irq %i\n",
short_irq);
short_irq = -1;
}
}
return 0;
}
void short_cleanup(void)
{
if (short_irq >= 0) {
outb(0x0, short_base + 2); /* disable the interrupt */
if (!share) free_irq(short_irq, NULL);
else free_irq(short_irq, short_sh_interrupt);
}
/* Make sure we don't leave work queue/tasklet functions running */
if (tasklet)
tasklet_disable(&short_tasklet);
else
flush_scheduled_work();
unregister_chrdev(major, "short");
if (use_mem) {
iounmap((void __iomem *)short_base);
release_mem_region(short_base, SHORT_NR_PORTS);
} else {
release_region(short_base,SHORT_NR_PORTS);
}
if (short_buffer) free_page(short_buffer);
}
module_init(short_init);
module_exit(short_cleanup);