arch/um/kernel/sigio.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
   4  */
   5
   6 #include <linux/interrupt.h>
   7 #include <irq_kern.h>
   8 #include <os.h>
   9 #include <sigio.h>
  10
  11 /* Protected by sigio_lock() called from write_sigio_workaround */
  12 static int sigio_irq_fd = -1;
  13
  14 static irqreturn_t sigio_interrupt(int irq, void *data)
  15 {
  16         char c;
  17
  18         os_read_file(sigio_irq_fd, &c, sizeof(c));
  19         return IRQ_HANDLED;
  20 }
  21
  22 int write_sigio_irq(int fd)
  23 {
  24         int err;
  25
  26         err = um_request_irq(SIGIO_WRITE_IRQ, fd, IRQ_READ, sigio_interrupt,
  27                              0, "write sigio", NULL);
  28         if (err < 0) {
  29                 printk(KERN_ERR "write_sigio_irq : um_request_irq failed, "
  30                        "err = %d\n", err);
  31                 return -1;
  32         }
  33         sigio_irq_fd = fd;
  34         return 0;
  35 }
  36
  37 /* These are called from os-Linux/sigio.c to protect its pollfds arrays. */
  38 static DEFINE_MUTEX(sigio_mutex);
  39
  40 void sigio_lock(void)
  41 {
  42         mutex_lock(&sigio_mutex);
  43 }
  44
  45 void sigio_unlock(void)
  46 {
  47         mutex_unlock(&sigio_mutex);
  48 }