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
  13 static int misc_registered;
  14 static int dev_opened;
  15
  16 static 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
  39 static ssize_t speakup_file_read(struct file *fp, char *buf, size_t nbytes, loff_t *ppos)
  40 {
  41         return 0;
  42 }
  43
  44 static int speakup_file_open(struct inode *ip, struct file *fp)
  45 {
  46         if (synth == NULL)
  47                 return -ENODEV;
  48         if (xchg(&dev_opened, 1))
  49                 return -EBUSY;
  50         return 0;
  51 }
  52
  53 static int speakup_file_release(struct inode *ip, struct file *fp)
  54 {
  55         dev_opened = 0;
  56         return 0;
  57 }
  58
  59 static struct file_operations synth_fops = {
  60         .read = speakup_file_read,
  61         .write = speakup_file_write,
  62         .open = speakup_file_open,
  63         .release = speakup_file_release,
  64 };
  65
  66 static struct miscdevice synth_device = {
  67         .minor = SYNTH_MINOR,
  68         .name = "synth",
  69         .fops = &synth_fops,
  70 };
  71
  72 void speakup_register_devsynth(void)
  73 {
  74         if (misc_registered != 0)
  75                 return;
  76 /* zero it so if register fails, deregister will not ref invalid ptrs */
  77         if (misc_register(&synth_device))
  78                 pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
  79         else {
  80                 pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n", MISC_MAJOR, SYNTH_MINOR);
  81                 misc_registered = 1;
  82         }
  83 }
  84
  85 void speakup_unregister_devsynth(void)
  86 {
  87         if (!misc_registered)
  88                 return;
  89         pr_info("speakup: unregistering synth device /dev/synth\n");
  90         misc_deregister(&synth_device);
  91         misc_registered = 0;
  92 }