short.c

LINUX设备驱动程序第二版配套源码 LINUX设备驱动程序第二版配套源码 Alessandro rubini&Jonathan corbet著 中国电力出版社 魏永明 骆刚 姜君译 69元

/*
 * short.c -- Simple Hardware Operations and Raw Tests
 * short.c -- also a brief example of interrupt handling ("short int")
 *
 * untested (by now) the hardware r/w
 *
 * Tested with 2.0.18 (intel & alpha -- but no irq available for me)
 * This module won't work on the sparc, where there's no concept of I/O space
 * 
 *********/

#ifndef __KERNEL__
#  define __KERNEL__
#endif
#ifndef MODULE
#  define MODULE
#endif

#ifdef __sparc__
#  error "This module can't compile on the Sparc platform"
#else

#include <linux/module.h>

#include <linux/sched.h>
#include <linux/kernel.h> /* printk() */
#include <linux/fs.h>     /* everything... */
#include <linux/errno.h>  /* error codes */
#include <linux/malloc.h>
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/tqueue.h>

#include <asm/io.h>
#include <asm/segment.h>

#include "sysdep.h"

int short_major = 0;
#ifdef __alpha__
int short_base = 0x3bc; /* Hmm.... FIXME */
#else
int short_base = 0x378; /* intel: default to lp0 */
#endif
int short_irq = -1;
unsigned long short_buffer = 0;
unsigned long volatile short_head;
volatile unsigned long short_tail;
struct wait_queue *short_queue;

static int probe = 0; /* select at load time how to probe irq line */
static int bh = 0; /* select at load time whether a bottom-half is used */
static int share = 0; /* select at load time whether install a shared irq */

/*
 * 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;
    MOD_INC_USE_COUNT;
    if (MINOR(inode->i_rdev) & 0x80) {
        filp->f_op = &short_i_fops; /* the interrupt-driven node */
    }
    return 0;
}

void short_release (struct inode *inode, struct file *filp)
{
    MOD_DEC_USE_COUNT;
}


/* first, the port-oriented device */

enum short_modes {SHORT_DEFAULT=0, SHORT_PAUSE, SHORT_STRING};

read_write_t short_read (struct inode *inode, struct file *filp,
                char *buf, count_t count)
{
    int retval = count;
    unsigned port = short_base + (MINOR(inode->i_rdev)&0x0f);
    int mode = (MINOR(inode->i_rdev)&0x70) >> 4;
    unsigned char *kbuf=kmalloc(count, GFP_KERNEL), *ptr;
    
    if (!kbuf) return -ENOMEM;
    ptr=kbuf;

    switch(mode) {
      case SHORT_STRING:
#ifndef __alpha__ /* Alpha doesn'e export insb: fall through */
        insb(port, ptr, count);
        break;
#endif

      case SHORT_DEFAULT:
        while (count--)
            *(ptr++) = inb(port);
        break;

      case SHORT_PAUSE:
        while (count--)
            *(ptr++) = inb_p(port);
        break;

      default: /* no more modes defined by now */
        retval = -EINVAL;
        break;
    }
    if (retval > 0)
        memcpy_tofs(buf, kbuf, retval);
    kfree(kbuf);
    return retval;
}

read_write_t short_write (struct inode *inode, struct file *filp,
                const char *buf, count_t count)
{
    int retval = count;
    unsigned port = short_base + (MINOR(inode->i_rdev)&0x0f);
    int mode = (MINOR(inode->i_rdev)&0x70) >> 4;
    unsigned char *kbuf=kmalloc(count, GFP_KERNEL), *ptr;

    if (!kbuf) return -ENOMEM;
    memcpy_fromfs(kbuf, buf, count);
    ptr=kbuf;

    switch(mode) {
      case SHORT_PAUSE:
        while (count--)
            outb_p(*(ptr++), port);
        break;

      case SHORT_STRING:
#ifndef __alpha__ /* Alpha doesn't export insb: fall through  */
        outsb(port, ptr, count);
        break;
#endif

      case SHORT_DEFAULT:
        while (count--)
            outb(*(ptr++), port);
        break;

      default: /* no more modes defined by now */
        retval = -EINVAL;
        break;
    }
    kfree(kbuf);
    return retval;
}

int short_select (struct inode *inode, struct file *filp,
                  int mode, select_table *table)
{
    return mode==SEL_EX ? 0 : 1; /* readable, writable, not-exceptionable */
}

struct file_operations short_fops = {
    NULL,          /* short_lseek */
    short_read,
    short_write,
    NULL,          /* short_readdir */
    short_select,
    NULL,          /* short_ioctl */
    NULL,          /* short_mmap */
    short_open,
    short_release,
    NULL,          /* short_fsync */
    NULL,          /* short_fasync */
                   /* nothing more, fill with NULLs */
};

/* then,  the interrupt-related device */

read_write_t short_i_read (struct inode *inode, struct file *filp,
                char *buf, count_t count)
{
    int count0;

    while (short_head == short_tail) {
        interruptible_sleep_on(&short_queue);
        if (current->signal & ~current->blocked) /* a signal arrived */
          return -ERESTARTSYS; /* tell the fs layer to handle it */
        /* else, loop */
    }
    /* 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;

    memcpy_tofs(buf, (char *)short_tail, count);
    short_tail += count;
    if (short_tail == short_buffer + PAGE_SIZE)
        short_tail = short_buffer;
    return count;
}

read_write_t short_i_write (struct inode *inode, struct file *filp,
                const char *buf, count_t count)
{
    int written = 0, odd = filp->f_pos & 1;
    unsigned port = short_base; /* output to the parallel data latch */

    while (written < count)
        outb(0xff * ((++written + odd) & 1), port);

    filp->f_pos += count;
    return written;
}

struct file_operations short_i_fops = {
    NULL,          /* short_i_lseek */
    short_i_read,
    short_i_write,
    NULL,          /* short_i_readdir */
    NULL,          /* short_i_select */
    NULL,          /* short_i_ioctl */
    NULL,          /* short_i_mmap */
    short_open,
    short_release,
    NULL,          /* short_i_fsync */
    NULL,          /* short_i_fasync */
                   /* nothing more, fill with NULLs */
};

/*
 * The interrupt handler has a different prototype whether it
 * is compiled with kernels older or newer than 1.3.70
 */

#if LINUX_VERSION_CODE < VERSION_CODE(1,3,70)
void short_interrupt(int irq, struct pt_regs *regs)
#else
void short_interrupt(int irq, void *dev_id, struct pt_regs *regs)
#endif
{
    struct timeval tv;
    do_gettimeofday(&tv);

    /* Write a 16 byte record. Assume PAGE_SIZE is a multiple of 16 */
    short_head += sprintf((char *)short_head,"%08u.%06u\n",
                          (int)(tv.tv_sec % 100000000), (int)(tv.tv_usec));
    if (short_head == short_buffer + PAGE_SIZE)
        short_head = short_buffer; /* wrap */

    wake_up_interruptible(&short_queue); /* awake any reading process */
}

/*
 * 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;
struct timeval *tv_tail=tv_data;

static struct tq_struct short_task; /* 0 by now, filled by init_module code */

int short_bh_count = 0;

void short_bottom_half(void *unused)
{
    int savecount = short_bh_count;
    short_bh_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 */

    short_head += sprintf((char *)short_head,"bh after %6i\n",savecount);
    if (short_head == short_buffer + PAGE_SIZE)
        short_head = short_buffer; /* wrap */