Revert "pktcdvd: remove driver."

This reverts commit f40eb99897af665f11858dd7b56edcb62c3f3c67.

There are apparently still users out there of this driver. While we'd
love to remove it to ease the maintenance burden, let's reinstate it
for now until better (userspace) solutions can be developed.

Link: https://lore.kernel.org/lkml/20230104190115.ceglfefco475ev6c@pali/
Reported-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 309 insertions, 0 deletions

diff --git a/include/linux/pktcdvd.h b/include/linux/pktcdvd.h
new file mode 100644
index 000000000000..f9c5ac80d59b
--- /dev/null
+++ b/include/linux/pktcdvd.h
@@ -0,0 +1,197 @@
+/*
+ * Copyright (C) 2000 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2001-2004 Peter Osterlund <petero2@telia.com>
+ *
+ * May be copied or modified under the terms of the GNU General Public
+ * License.  See linux/COPYING for more information.
+ *
+ * Packet writing layer for ATAPI and SCSI CD-R, CD-RW, DVD-R, and
+ * DVD-RW devices.
+ *
+ */
+#ifndef __PKTCDVD_H
+#define __PKTCDVD_H
+
+#include <linux/blkdev.h>
+#include <linux/completion.h>
+#include <linux/cdrom.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/mempool.h>
+#include <uapi/linux/pktcdvd.h>
+
+/* default bio write queue congestion marks */
+#define PKT_WRITE_CONGESTION_ON    10000
+#define PKT_WRITE_CONGESTION_OFF   9000
+
+
+struct packet_settings
+{
+	__u32			size;		/* packet size in (512 byte) sectors */
+	__u8			fp;		/* fixed packets */
+	__u8			link_loss;	/* the rest is specified
+						 * as per Mt Fuji */
+	__u8			write_type;
+	__u8			track_mode;
+	__u8			block_mode;
+};
+
+/*
+ * Very crude stats for now
+ */
+struct packet_stats
+{
+	unsigned long		pkt_started;
+	unsigned long		pkt_ended;
+	unsigned long		secs_w;
+	unsigned long		secs_rg;
+	unsigned long		secs_r;
+};
+
+struct packet_cdrw
+{
+	struct list_head	pkt_free_list;
+	struct list_head	pkt_active_list;
+	spinlock_t		active_list_lock; /* Serialize access to pkt_active_list */
+	struct task_struct	*thread;
+	atomic_t		pending_bios;
+};
+
+/*
+ * Switch to high speed reading after reading this many kilobytes
+ * with no interspersed writes.
+ */
+#define HI_SPEED_SWITCH 512
+
+struct packet_iosched
+{
+	atomic_t		attention;	/* Set to non-zero when queue processing is needed */
+	int			writing;	/* Non-zero when writing, zero when reading */
+	spinlock_t		lock;		/* Protecting read/write queue manipulations */
+	struct bio_list		read_queue;
+	struct bio_list		write_queue;
+	sector_t		last_write;	/* The sector where the last write ended */
+	int			successive_reads;
+};
+
+/*
+ * 32 buffers of 2048 bytes
+ */
+#if (PAGE_SIZE % CD_FRAMESIZE) != 0
+#error "PAGE_SIZE must be a multiple of CD_FRAMESIZE"
+#endif
+#define PACKET_MAX_SIZE		128
+#define FRAMES_PER_PAGE		(PAGE_SIZE / CD_FRAMESIZE)
+#define PACKET_MAX_SECTORS	(PACKET_MAX_SIZE * CD_FRAMESIZE >> 9)
+
+enum packet_data_state {
+	PACKET_IDLE_STATE,			/* Not used at the moment */
+	PACKET_WAITING_STATE,			/* Waiting for more bios to arrive, so */
+						/* we don't have to do as much */
+						/* data gathering */
+	PACKET_READ_WAIT_STATE,			/* Waiting for reads to fill in holes */
+	PACKET_WRITE_WAIT_STATE,		/* Waiting for the write to complete */
+	PACKET_RECOVERY_STATE,			/* Recover after read/write errors */
+	PACKET_FINISHED_STATE,			/* After write has finished */
+
+	PACKET_NUM_STATES			/* Number of possible states */
+};
+
+/*
+ * Information needed for writing a single packet
+ */
+struct pktcdvd_device;
+
+struct packet_data
+{
+	struct list_head	list;
+
+	spinlock_t		lock;		/* Lock protecting state transitions and */
+						/* orig_bios list */
+
+	struct bio_list		orig_bios;	/* Original bios passed to pkt_make_request */
+						/* that will be handled by this packet */
+	int			write_size;	/* Total size of all bios in the orig_bios */
+						/* list, measured in number of frames */
+
+	struct bio		*w_bio;		/* The bio we will send to the real CD */
+						/* device once we have all data for the */
+						/* packet we are going to write */
+	sector_t		sector;		/* First sector in this packet */
+	int			frames;		/* Number of frames in this packet */
+
+	enum packet_data_state	state;		/* Current state */
+	atomic_t		run_sm;		/* Incremented whenever the state */
+						/* machine needs to be run */
+	long			sleep_time;	/* Set this to non-zero to make the state */
+						/* machine run after this many jiffies. */
+
+	atomic_t		io_wait;	/* Number of pending IO operations */
+	atomic_t		io_errors;	/* Number of read/write errors during IO */
+
+	struct bio		*r_bios[PACKET_MAX_SIZE]; /* bios to use during data gathering */
+	struct page		*pages[PACKET_MAX_SIZE / FRAMES_PER_PAGE];
+
+	int			cache_valid;	/* If non-zero, the data for the zone defined */
+						/* by the sector variable is completely cached */
+						/* in the pages[] vector. */
+
+	int			id;		/* ID number for debugging */
+	struct pktcdvd_device	*pd;
+};
+
+struct pkt_rb_node {
+	struct rb_node		rb_node;
+	struct bio		*bio;
+};
+
+struct packet_stacked_data
+{
+	struct bio		*bio;		/* Original read request bio */
+	struct pktcdvd_device	*pd;
+};
+#define PSD_POOL_SIZE		64
+
+struct pktcdvd_device
+{
+	struct block_device	*bdev;		/* dev attached */
+	dev_t			pkt_dev;	/* our dev */
+	char			name[20];
+	struct packet_settings	settings;
+	struct packet_stats	stats;
+	int			refcnt;		/* Open count */
+	int			write_speed;	/* current write speed, kB/s */
+	int			read_speed;	/* current read speed, kB/s */
+	unsigned long		offset;		/* start offset */
+	__u8			mode_offset;	/* 0 / 8 */
+	__u8			type;
+	unsigned long		flags;
+	__u16			mmc3_profile;
+	__u32			nwa;		/* next writable address */
+	__u32			lra;		/* last recorded address */
+	struct packet_cdrw	cdrw;
+	wait_queue_head_t	wqueue;
+
+	spinlock_t		lock;		/* Serialize access to bio_queue */
+	struct rb_root		bio_queue;	/* Work queue of bios we need to handle */
+	int			bio_queue_size;	/* Number of nodes in bio_queue */
+	bool			congested;	/* Someone is waiting for bio_queue_size
+						 * to drop. */
+	sector_t		current_sector;	/* Keep track of where the elevator is */
+	atomic_t		scan_queue;	/* Set to non-zero when pkt_handle_queue */
+						/* needs to be run. */
+	mempool_t		rb_pool;	/* mempool for pkt_rb_node allocations */
+
+	struct packet_iosched   iosched;
+	struct gendisk		*disk;
+
+	int			write_congestion_off;
+	int			write_congestion_on;
+
+	struct device		*dev;		/* sysfs pktcdvd[0-7] dev */
+
+	struct dentry		*dfs_d_root;	/* debugfs: devname directory */
+	struct dentry		*dfs_f_info;	/* debugfs: info file */
+};
+
+#endif /* __PKTCDVD_H */
diff --git a/include/uapi/linux/pktcdvd.h b/include/uapi/linux/pktcdvd.h
new file mode 100644
index 000000000000..9cbb55d21c94
--- /dev/null
+++ b/include/uapi/linux/pktcdvd.h
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2000 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2001-2004 Peter Osterlund <petero2@telia.com>
+ *
+ * May be copied or modified under the terms of the GNU General Public
+ * License.  See linux/COPYING for more information.
+ *
+ * Packet writing layer for ATAPI and SCSI CD-R, CD-RW, DVD-R, and
+ * DVD-RW devices.
+ *
+ */
+#ifndef _UAPI__PKTCDVD_H
+#define _UAPI__PKTCDVD_H
+
+#include <linux/types.h>
+
+/*
+ * 1 for normal debug messages, 2 is very verbose. 0 to turn it off.
+ */
+#define PACKET_DEBUG		1
+
+#define	MAX_WRITERS		8
+
+#define PKT_RB_POOL_SIZE	512
+
+/*
+ * How long we should hold a non-full packet before starting data gathering.
+ */
+#define PACKET_WAIT_TIME	(HZ * 5 / 1000)
+
+/*
+ * use drive write caching -- we need deferred error handling to be
+ * able to successfully recover with this option (drive will return good
+ * status as soon as the cdb is validated).
+ */
+#if defined(CONFIG_CDROM_PKTCDVD_WCACHE)
+#define USE_WCACHING		1
+#else
+#define USE_WCACHING		0
+#endif
+
+/*
+ * No user-servicable parts beyond this point ->
+ */
+
+/*
+ * device types
+ */
+#define PACKET_CDR		1
+#define	PACKET_CDRW		2
+#define PACKET_DVDR		3
+#define PACKET_DVDRW		4
+
+/*
+ * flags
+ */
+#define PACKET_WRITABLE		1	/* pd is writable */
+#define PACKET_NWA_VALID	2	/* next writable address valid */
+#define PACKET_LRA_VALID	3	/* last recorded address valid */
+#define PACKET_MERGE_SEGS	4	/* perform segment merging to keep */
+					/* underlying cdrom device happy */
+
+/*
+ * Disc status -- from READ_DISC_INFO
+ */
+#define PACKET_DISC_EMPTY	0
+#define PACKET_DISC_INCOMPLETE	1
+#define PACKET_DISC_COMPLETE	2
+#define PACKET_DISC_OTHER	3
+
+/*
+ * write type, and corresponding data block type
+ */
+#define PACKET_MODE1		1
+#define PACKET_MODE2		2
+#define PACKET_BLOCK_MODE1	8
+#define PACKET_BLOCK_MODE2	10
+
+/*
+ * Last session/border status
+ */
+#define PACKET_SESSION_EMPTY		0
+#define PACKET_SESSION_INCOMPLETE	1
+#define PACKET_SESSION_RESERVED		2
+#define PACKET_SESSION_COMPLETE		3
+
+#define PACKET_MCN			"4a656e734178626f65323030300000"
+
+#undef PACKET_USE_LS
+
+#define PKT_CTRL_CMD_SETUP	0
+#define PKT_CTRL_CMD_TEARDOWN	1
+#define PKT_CTRL_CMD_STATUS	2
+
+struct pkt_ctrl_command {
+	__u32 command;				/* in: Setup, teardown, status */
+	__u32 dev_index;			/* in/out: Device index */
+	__u32 dev;				/* in/out: Device nr for cdrw device */
+	__u32 pkt_dev;				/* in/out: Device nr for packet device */
+	__u32 num_devices;			/* out: Largest device index + 1 */
+	__u32 padding;				/* Not used */
+};
+
+/*
+ * packet ioctls
+ */
+#define PACKET_IOCTL_MAGIC	('X')
+#define PACKET_CTRL_CMD		_IOWR(PACKET_IOCTL_MAGIC, 1, struct pkt_ctrl_command)
+
+
+#endif /* _UAPI__PKTCDVD_H */