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,
  40         loff_t *ppos)
  41 {
  42         return 0;
  43 }
  44
  45 static 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
  54 static int speakup_file_release(struct inode *ip, struct file *fp)
  55 {
  56         dev_opened = 0;
  57         return 0;
  58 }
  59
  60 static 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
  67 static struct miscdevice synth_device = {
  68         .minor = SYNTH_MINOR,
  69         .name = "synth",
  70         .fops = &synth_fops,
  71 };
  72
  73 void 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
  87 void 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 }