A recent patch to add CD-ROM emulation to your Android kernel (3.18+).

cdrom-emulation.patch

From 45b0c1da3ed92b232b35cc2922e696a5d0fc5c16 Mon Sep 17 00:00:00 2001
From: MusiKid
Date: Sat, 23 Sep 2017 19:46:02 +0200
Subject: [PATCH] Add CD-ROM emulation support.

# This is a recent patch to add CD-ROM emulation to your kernel 

---
 drivers/usb/gadget/function/f_mass_storage.c | 25 +++++++++++++++++++++++++
 drivers/usb/gadget/function/storage_common.c |  4 ++--
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
index 99d8675483e..bea106f3d00 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -2813,6 +2813,14 @@ static ssize_t file_show(struct device *dev, struct device_attribute *attr,
 	return fsg_show_file(curlun, filesem, buf);
 }
 
+static ssize_t cdrom_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct fsg_lun		*curlun = fsg_lun_from_dev(dev);
+
+	return fsg_show_cdrom(curlun, buf);
+}
+
 static ssize_t ro_store(struct device *dev, struct device_attribute *attr,
 			const char *buf, size_t count)
 {
@@ -2830,6 +2838,16 @@ static ssize_t nofua_store(struct device *dev, struct device_attribute *attr,
 	return fsg_store_nofua(curlun, buf, count);
 }
 
+static ssize_t cdrom_store(struct device *dev, struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	struct fsg_lun		*curlun = fsg_lun_from_dev(dev);
+	struct rw_semaphore	*filesem = dev_get_drvdata(dev);
+
+	return fsg_store_cdrom(curlun, filesem, buf, count);
+}
+
+
 static ssize_t file_store(struct device *dev, struct device_attribute *attr,
 			  const char *buf, size_t count)
 {
@@ -2842,8 +2860,10 @@ static ssize_t file_store(struct device *dev, struct device_attribute *attr,
 static DEVICE_ATTR_RW(ro);
 static DEVICE_ATTR_RW(nofua);
 static DEVICE_ATTR_RW(file);
+static DEVICE_ATTR_RW(cdrom);
 static DEVICE_ATTR(perf, 0644, fsg_show_perf, fsg_store_perf);
 
+
 static struct device_attribute dev_attr_ro_cdrom = __ATTR_RO(ro);
 static struct device_attribute dev_attr_file_nonremovable = __ATTR_RO(file);
 
@@ -2993,6 +3013,7 @@ static inline void fsg_common_remove_sysfs(struct fsg_lun *lun)
 	device_remove_file(&lun->dev, &dev_attr_ro);
 	device_remove_file(&lun->dev, &dev_attr_file);
 	device_remove_file(&lun->dev, &dev_attr_perf);
+	device_remove_file(&lun->dev, &dev_attr_cdrom);
 }
 
 void fsg_common_remove_lun(struct fsg_lun *lun, bool sysfs)
@@ -3115,6 +3136,10 @@ static inline int fsg_common_add_sysfs(struct fsg_common *common,
 		return rc;
 	}
 
+	rc = device_create_file(&lun->dev, &dev_attr_cdrom);
+	if (rc)
+		goto error;
+
 	rc = device_create_file(&lun->dev,
 				lun->cdrom
 			      ? &dev_attr_ro_cdrom
diff --git a/drivers/usb/gadget/function/storage_common.c b/drivers/usb/gadget/function/storage_common.c
index 69796530f2b..1328f32a812 100644
--- a/drivers/usb/gadget/function/storage_common.c
+++ b/drivers/usb/gadget/function/storage_common.c
@@ -498,8 +498,8 @@ EXPORT_SYMBOL_GPL(fsg_store_file);
 ssize_t fsg_store_cdrom(struct fsg_lun *curlun, struct rw_semaphore *filesem,
 			const char *buf, size_t count)
 {
-	bool		cdrom;
-	int		ret;
+	int		cdrom;
+	ssize_t		ret;
 
 	ret = strtobool(buf, &cdrom);
 	if (ret)