drivers/accessibility/speakup/devsynth.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/errno.h>
   3 #include <linux/miscdevice.h>   /* for misc_register, and MISC_DYNAMIC_MINOR */
   4 #include <linux/types.h>
   5 #include <linux/uaccess.h>
   6
   7 #include "speakup.h"
   8 #include "spk_priv.h"
   9
  10 static int misc_registered;
  11 static int dev_opened;
  12
  13 static ssize_t speakup_file_write(struct file *fp, const char __user *buffer,
  14                                   size_t nbytes, loff_t *ppos)
  15 {
  16         size_t count = nbytes;
  17         const char __user *ptr = buffer;
  18         size_t bytes;
  19         unsigned long flags;
  20         u_char buf[256];
  21
  22         if (!synth)
  23                 return -ENODEV;
  24         while (count > 0) {
  25                 bytes = min(count, sizeof(buf));
  26                 if (copy_from_user(buf, ptr, bytes))
  27                         return -EFAULT;
  28                 count -= bytes;
  29                 ptr += bytes;
  30                 spin_lock_irqsave(&speakup_info.spinlock, flags);
  31                 synth_write(buf, bytes);
  32                 spin_unlock_irqrestore(&speakup_info.spinlock, flags);
  33         }
  34         return (ssize_t)nbytes;
  35 }
  36
  37 static ssize_t speakup_file_read(struct file *fp, char __user *buf,
  38                                  size_t nbytes, loff_t *ppos)
  39 {
  40         return 0;
  41 }
  42
  43 static int speakup_file_open(struct inode *ip, struct file *fp)
  44 {
  45         if (!synth)
  46                 return -ENODEV;
  47         if (xchg(&dev_opened, 1))
  48                 return -EBUSY;
  49         return 0;
  50 }
  51
  52 static int speakup_file_release(struct inode *ip, struct file *fp)
  53 {
  54         dev_opened = 0;
  55         return 0;
  56 }
  57
  58 static const struct file_operations synth_fops = {
  59         .read = speakup_file_read,
  60         .write = speakup_file_write,
  61         .open = speakup_file_open,
  62         .release = speakup_file_release,
  63 };
  64
  65 static struct miscdevice synth_device = {
  66         .minor = MISC_DYNAMIC_MINOR,
  67         .name = "synth",
  68         .fops = &synth_fops,
  69 };
  70
  71 void speakup_register_devsynth(void)
  72 {
  73         if (misc_registered != 0)
  74                 return;
  75 /* zero it so if register fails, deregister will not ref invalid ptrs */
  76         if (misc_register(&synth_device)) {
  77                 pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
  78         } else {
  79                 pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",
  80                         MISC_MAJOR, synth_device.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 }