LXR linux/drivers/staging/speakup/devsynth.c

   1#include <linux/errno.h>
   2#include <linux/miscdevice.h>   /* for misc_register, and SYNTH_MINOR */
   3#include <linux/types.h>
   4#include <linux/uaccess.h>
   5
   6#include "speakup.h"
   7#include "spk_priv.h"
   8
   9#ifndef SYNTH_MINOR
  10#define SYNTH_MINOR 25
  11#endif
  12
  13static int misc_registered;
  14static int dev_opened;
  15
  16static ssize_t speakup_file_write(struct file *fp, const char *buffer,
  17                   size_t nbytes, loff_t *ppos)
  18{
  19        size_t count = nbytes;
  20        const char *ptr = buffer;
  21        size_t bytes;
  22        unsigned long flags;
  23        u_char buf[256];
  24
  25        if (synth == NULL)
  26                return -ENODEV;
  27        while (count > 0) {
  28                bytes = min(count, sizeof(buf));
  29                if (copy_from_user(buf, ptr, bytes))
  30                        return -EFAULT;
  31                count -= bytes;
  32                ptr += bytes;
  33                spk_lock(flags);
  34                synth_write(buf, bytes);
  35                spk_unlock(flags);
  36        }
  37        return (ssize_t) nbytes;
  38}
  39
  40static ssize_t speakup_file_read(struct file *fp, char *buf, size_t nbytes,
  41        loff_t *ppos)
  42{
  43        return 0;
  44}
  45
  46static int speakup_file_open(struct inode *ip, struct file *fp)
  47{
  48        if (synth == NULL)
  49                return -ENODEV;
  50        if (xchg(&dev_opened, 1))
  51                return -EBUSY;
  52        return 0;
  53}
  54
  55static int speakup_file_release(struct inode *ip, struct file *fp)
  56{
  57        dev_opened = 0;
  58        return 0;
  59}
  60
  61static const struct file_operations synth_fops = {
  62        .read = speakup_file_read,
  63        .write = speakup_file_write,
  64        .open = speakup_file_open,
  65        .release = speakup_file_release,
  66};
  67
  68static struct miscdevice synth_device = {
  69        .minor = SYNTH_MINOR,
  70        .name = "synth",
  71        .fops = &synth_fops,
  72};
  73
  74void speakup_register_devsynth(void)
  75{
  76        if (misc_registered != 0)
  77                return;
  78/* zero it so if register fails, deregister will not ref invalid ptrs */
  79        if (misc_register(&synth_device))
  80                pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
  81        else {
  82                pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",
  83                        MISC_MAJOR, SYNTH_MINOR);
  84                misc_registered = 1;
  85        }
  86}
  87
  88void speakup_unregister_devsynth(void)
  89{
  90        if (!misc_registered)
  91                return;
  92        pr_info("speakup: unregistering synth device /dev/synth\n");
  93        misc_deregister(&synth_device);
  94        misc_registered = 0;
  95}
  96