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