1 files changed, 92 insertions, 0 deletions
diff --git a/drivers/accessibility/speakup/devsynth.c b/drivers/accessibility/speakup/devsynth.c
new file mode 100644
index 000000000000..d30571663585
--- /dev/null
+++ b/drivers/accessibility/speakup/devsynth.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/errno.h>
+#include <linux/miscdevice.h>	/* for misc_register, and MISC_DYNAMIC_MINOR */
+#include <linux/types.h>
+#include <linux/uaccess.h>
+
+#include "speakup.h"
+#include "spk_priv.h"
+
+static int misc_registered;
+static int dev_opened;
+
+static ssize_t speakup_file_write(struct file *fp, const char __user *buffer,
+				  size_t nbytes, loff_t *ppos)
+{
+	size_t count = nbytes;
+	const char __user *ptr = buffer;
+	size_t bytes;
+	unsigned long flags;
+	u_char buf[256];
+
+	if (!synth)
+		return -ENODEV;
+	while (count > 0) {
+		bytes = min(count, sizeof(buf));
+		if (copy_from_user(buf, ptr, bytes))
+			return -EFAULT;
+		count -= bytes;
+		ptr += bytes;
+		spin_lock_irqsave(&speakup_info.spinlock, flags);
+		synth_write(buf, bytes);
+		spin_unlock_irqrestore(&speakup_info.spinlock, flags);
+	}
+	return (ssize_t)nbytes;
+}
+
+static ssize_t speakup_file_read(struct file *fp, char __user *buf,
+				 size_t nbytes, loff_t *ppos)
+{
+	return 0;
+}
+
+static int speakup_file_open(struct inode *ip, struct file *fp)
+{
+	if (!synth)
+		return -ENODEV;
+	if (xchg(&dev_opened, 1))
+		return -EBUSY;
+	return 0;
+}
+
+static int speakup_file_release(struct inode *ip, struct file *fp)
+{
+	dev_opened = 0;
+	return 0;
+}
+
+static const struct file_operations synth_fops = {
+	.read = speakup_file_read,
+	.write = speakup_file_write,
+	.open = speakup_file_open,
+	.release = speakup_file_release,
+};
+
+static struct miscdevice synth_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "synth",
+	.fops = &synth_fops,
+};
+
+void speakup_register_devsynth(void)
+{
+	if (misc_registered != 0)
+		return;
+/* zero it so if register fails, deregister will not ref invalid ptrs */
+	if (misc_register(&synth_device)) {
+		pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
+	} else {
+		pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",
+			MISC_MAJOR, synth_device.minor);
+		misc_registered = 1;
+	}
+}
+
+void speakup_unregister_devsynth(void)
+{
+	if (!misc_registered)
+		return;
+	pr_info("speakup: unregistering synth device /dev/synth\n");
+	misc_deregister(&synth_device);
+	misc_registered = 0;
+}