staging: fwserial: delete the driver.

In the years since it was added (2012), no one has stepped up to
maintain this properly and get it merged into the kernel tree.  So
remove it as it's obviously not being used.

If it is being used, we can easily revert this and take the time to get
it out of the staging tree.

Link: https://lore.kernel.org/r/20220924105817.808385-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/Kconfig

@@ -60,8 +60,6 @@ source "drivers/staging/board/Kconfig"
 
 source "drivers/staging/gdm724x/Kconfig"
 
-source "drivers/staging/fwserial/Kconfig"
-
 source "drivers/staging/clocking-wizard/Kconfig"
 
 source "drivers/staging/fbtft/Kconfig"

drivers/staging/Makefile

@@ -20,7 +20,6 @@ obj-$(CONFIG_USB_EMXX)		+= emxx_udc/
 obj-$(CONFIG_MFD_NVEC)		+= nvec/
 obj-$(CONFIG_STAGING_BOARD)	+= board/
 obj-$(CONFIG_LTE_GDM724X)	+= gdm724x/
-obj-$(CONFIG_FIREWIRE_SERIAL)	+= fwserial/
 obj-$(CONFIG_COMMON_CLK_XLNX_CLKWZRD)	+= clocking-wizard/
 obj-$(CONFIG_FB_TFT)		+= fbtft/
 obj-$(CONFIG_MOST)		+= most/

drivers/staging/fwserial/Kconfig

-# SPDX-License-Identifier: GPL-2.0
-config FIREWIRE_SERIAL
-	tristate "TTY over Firewire"
-	depends on FIREWIRE && TTY
-	help
-	  This enables TTY over IEEE 1394, providing high-speed serial
-	  connectivity to cabled peers. This driver implements a
-	  ad-hoc transport protocol and is currently limited to
-	  Linux-to-Linux communication.
-
-	  To compile this driver as a module, say M here:  the module will
-	  be called firewire-serial.
-
-if FIREWIRE_SERIAL
-
-config FWTTY_MAX_TOTAL_PORTS
-	int "Maximum number of serial ports supported"
-	default "64"
-	help
-	  Set this to the maximum number of serial ports you want the
-	  firewire-serial driver to support.
-
-config FWTTY_MAX_CARD_PORTS
-	int "Maximum number of serial ports supported per adapter"
-	range 0 FWTTY_MAX_TOTAL_PORTS
-	default "32"
-	help
-	  Set this to the maximum number of serial ports each firewire
-	  adapter supports. The actual number of serial ports registered
-	  is set with the module parameter "ttys".
-
-endif

drivers/staging/fwserial/Makefile

-# SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_FIREWIRE_SERIAL) += firewire-serial.o
-firewire-serial-objs := fwserial.o dma_fifo.o

drivers/staging/fwserial/TODO

-TODOs prior to this driver moving out of staging
-------------------------------------------------
-1. Implement retries for RCODE_BUSY, RCODE_NO_ACK and RCODE_SEND_ERROR
-   - I/O is handled asynchronously which presents some issues when error
-     conditions occur.
-2. Implement _robust_ console on top of this. The existing prototype console
-   driver is not ready for the big leagues yet.
-3. Expose means of controlling attach/detach of peers via sysfs. Include
-   GUID-to-port matching/whitelist/blacklist.
-
--- Issues with firewire stack --
-1. This driver uses the same unregistered vendor id that the firewire core does
-     (0xd00d1e). Perhaps this could be exposed as a define in
-     firewire.h?

drivers/staging/fwserial/dma_fifo.c

-// SPDX-License-Identifier: GPL-2.0+
-/*
- * DMA-able FIFO implementation
- *
- * Copyright (C) 2012 Peter Hurley <peter@hurleysoftware.com>
- */
-
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/list.h>
-#include <linux/bug.h>
-
-#include "dma_fifo.h"
-
-#ifdef DEBUG_TRACING
-#define df_trace(s, args...) pr_debug(s, ##args)
-#else
-#define df_trace(s, args...)
-#endif
-
-#define FAIL(fifo, condition, format...) ({				\
-	fifo->corrupt = !!(condition);					\
-	WARN(fifo->corrupt, format);					\
-})
-
-/*
- * private helper fn to determine if check is in open interval (lo,hi)
- */
-static bool addr_check(unsigned int check, unsigned int lo, unsigned int hi)
-{
-	return check - (lo + 1) < (hi - 1) - lo;
-}
-
-/**
- * dma_fifo_init: initialize the fifo to a valid but inoperative state
- * @fifo: address of in-place "struct dma_fifo" object
- */
-void dma_fifo_init(struct dma_fifo *fifo)
-{
-	memset(fifo, 0, sizeof(*fifo));
-	INIT_LIST_HEAD(&fifo->pending);
-}
-
-/**
- * dma_fifo_alloc - initialize and allocate dma_fifo
- * @fifo: address of in-place "struct dma_fifo" object
- * @size: 'apparent' size, in bytes, of fifo
- * @align: dma alignment to maintain (should be at least cpu cache alignment),
- *         must be power of 2
- * @tx_limit: maximum # of bytes transmissible per dma (rounded down to
- *            multiple of alignment, but at least align size)
- * @open_limit: maximum # of outstanding dma transactions allowed
- * @gfp_mask: get_free_pages mask, passed to kmalloc()
- *
- * The 'apparent' size will be rounded up to next greater aligned size.
- * Returns 0 if no error, otherwise an error code
- */
-int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned int align,
-		   int tx_limit, int open_limit, gfp_t gfp_mask)
-{
-	int capacity;
-
-	if (!is_power_of_2(align) || size < 0)
-		return -EINVAL;
-
-	size = round_up(size, align);
-	capacity = size + align * open_limit + align * DMA_FIFO_GUARD;
-	fifo->data = kmalloc(capacity, gfp_mask);
-	if (!fifo->data)
-		return -ENOMEM;
-
-	fifo->in = 0;
-	fifo->out = 0;
-	fifo->done = 0;
-	fifo->size = size;
-	fifo->avail = size;
-	fifo->align = align;
-	fifo->tx_limit = max_t(int, round_down(tx_limit, align), align);
-	fifo->open = 0;
-	fifo->open_limit = open_limit;
-	fifo->guard = size + align * open_limit;
-	fifo->capacity = capacity;
-	fifo->corrupt = 0;
-
-	return 0;
-}
-
-/**
- * dma_fifo_free - frees the fifo
- * @fifo: address of in-place "struct dma_fifo" to free
- *
- * Also reinits the fifo to a valid but inoperative state. This
- * allows the fifo to be reused with a different target requiring
- * different fifo parameters.
- */
-void dma_fifo_free(struct dma_fifo *fifo)
-{
-	struct dma_pending *pending, *next;
-
-	if (!fifo->data)
-		return;
-
-	list_for_each_entry_safe(pending, next, &fifo->pending, link)
-		list_del_init(&pending->link);
-	kfree(fifo->data);
-	fifo->data = NULL;
-}
-
-/**
- * dma_fifo_reset - dumps the fifo contents and reinits for reuse
- * @fifo: address of in-place "struct dma_fifo" to reset
- */
-void dma_fifo_reset(struct dma_fifo *fifo)
-{
-	struct dma_pending *pending, *next;
-
-	if (!fifo->data)
-		return;
-
-	list_for_each_entry_safe(pending, next, &fifo->pending, link)
-		list_del_init(&pending->link);
-	fifo->in = 0;
-	fifo->out = 0;
-	fifo->done = 0;
-	fifo->avail = fifo->size;
-	fifo->open = 0;
-	fifo->corrupt = 0;
-}
-
-/**
- * dma_fifo_in - copies data into the fifo
- * @fifo: address of in-place "struct dma_fifo" to write to
- * @src: buffer to copy from
- * @n: # of bytes to copy
- *
- * Returns the # of bytes actually copied, which can be less than requested if
- * the fifo becomes full. If < 0, return is error code.
- */
-int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n)
-{
-	int ofs, l;
-
-	if (!fifo->data)
-		return -ENOENT;
-	if (fifo->corrupt)
-		return -ENXIO;
-
-	if (n > fifo->avail)
-		n = fifo->avail;
-	if (n <= 0)
-		return 0;
-
-	ofs = fifo->in % fifo->capacity;
-	l = min(n, fifo->capacity - ofs);
-	memcpy(fifo->data + ofs, src, l);
-	memcpy(fifo->data, src + l, n - l);
-
-	if (FAIL(fifo, addr_check(fifo->done, fifo->in, fifo->in + n) ||
-		 fifo->avail < n,
-		 "fifo corrupt: in:%u out:%u done:%u n:%d avail:%d",
-		 fifo->in, fifo->out, fifo->done, n, fifo->avail))
-		return -ENXIO;
-
-	fifo->in += n;
-	fifo->avail -= n;
-
-	df_trace("in:%u out:%u done:%u n:%d avail:%d", fifo->in, fifo->out,
-		 fifo->done, n, fifo->avail);
-
-	return n;
-}
-
-/**
- * dma_fifo_out_pend - gets address/len of next avail read and marks as pended
- * @fifo: address of in-place "struct dma_fifo" to read from
- * @pended: address of structure to fill with read address/len
- *          The data/len fields will be NULL/0 if no dma is pended.
- *
- * Returns the # of used bytes remaining in fifo (ie, if > 0, more data
- * remains in the fifo that was not pended). If < 0, return is error code.
- */
-int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended)
-{
-	unsigned int len, n, ofs, l, limit;
-
-	if (!fifo->data)
-		return -ENOENT;
-	if (fifo->corrupt)
-		return -ENXIO;
-
-	pended->len = 0;
-	pended->data = NULL;
-	pended->out = fifo->out;
-
-	len = fifo->in - fifo->out;
-	if (!len)
-		return -ENODATA;
-	if (fifo->open == fifo->open_limit)
-		return -EAGAIN;
-
-	n = len;
-	ofs = fifo->out % fifo->capacity;
-	l = fifo->capacity - ofs;
-	limit = min_t(unsigned int, l, fifo->tx_limit);
-	if (n > limit) {
-		n = limit;
-		fifo->out += limit;
-	} else if (ofs + n > fifo->guard) {
-		fifo->out += l;
-		fifo->in = fifo->out;
-	} else {
-		fifo->out += round_up(n, fifo->align);
-		fifo->in = fifo->out;
-	}
-
-	df_trace("in: %u out: %u done: %u n: %d len: %u avail: %d", fifo->in,
-		 fifo->out, fifo->done, n, len, fifo->avail);
-
-	pended->len = n;
-	pended->data = fifo->data + ofs;
-	pended->next = fifo->out;
-	list_add_tail(&pended->link, &fifo->pending);
-	++fifo->open;
-
-	if (FAIL(fifo, fifo->open > fifo->open_limit,
-		 "past open limit:%d (limit:%d)",
-		 fifo->open, fifo->open_limit))
-		return -ENXIO;
-	if (FAIL(fifo, fifo->out & (fifo->align - 1),
-		 "fifo out unaligned:%u (align:%u)",
-		 fifo->out, fifo->align))
-		return -ENXIO;
-
-	return len - n;
-}
-
-/**
- * dma_fifo_out_complete - marks pended dma as completed
- * @fifo: address of in-place "struct dma_fifo" which was read from
- * @complete: address of structure for previously pended dma to mark completed
- */
-int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete)
-{
-	struct dma_pending *pending, *next, *tmp;
-
-	if (!fifo->data)
-		return -ENOENT;
-	if (fifo->corrupt)
-		return -ENXIO;
-	if (list_empty(&fifo->pending) && fifo->open == 0)
-		return -EINVAL;
-
-	if (FAIL(fifo, list_empty(&fifo->pending) != (fifo->open == 0),
-		 "pending list disagrees with open count:%d",
-		 fifo->open))
-		return -ENXIO;
-
-	tmp = complete->data;
-	*tmp = *complete;
-	list_replace(&complete->link, &tmp->link);
-	dp_mark_completed(tmp);
-
-	/* Only update the fifo in the original pended order */
-	list_for_each_entry_safe(pending, next, &fifo->pending, link) {
-		if (!dp_is_completed(pending)) {
-			df_trace("still pending: saved out: %u len: %d",
-				 pending->out, pending->len);
-			break;
-		}
-
-		if (FAIL(fifo, pending->out != fifo->done ||
-			 addr_check(fifo->in, fifo->done, pending->next),
-			 "in:%u out:%u done:%u saved:%u next:%u",
-			 fifo->in, fifo->out, fifo->done, pending->out,
-			 pending->next))
-			return -ENXIO;
-
-		list_del_init(&pending->link);
-		fifo->done = pending->next;
-		fifo->avail += pending->len;
-		--fifo->open;
-
-		df_trace("in: %u out: %u done: %u len: %u avail: %d", fifo->in,
-			 fifo->out, fifo->done, pending->len, fifo->avail);
-	}
-
-	if (FAIL(fifo, fifo->open < 0, "open dma:%d < 0", fifo->open))
-		return -ENXIO;
-	if (FAIL(fifo, fifo->avail > fifo->size, "fifo avail:%d > size:%d",
-		 fifo->avail, fifo->size))
-		return -ENXIO;
-
-	return 0;
-}

drivers/staging/fwserial/dma_fifo.h

-/* SPDX-License-Identifier: GPL-2.0+ */
-/*
- * DMA-able FIFO interface
- *
- * Copyright (C) 2012 Peter Hurley <peter@hurleysoftware.com>
- */
-
-#ifndef _DMA_FIFO_H_
-#define _DMA_FIFO_H_
-
-/**
- * The design basis for the DMA FIFO is to provide an output side that
- * complies with the streaming DMA API design that can be DMA'd from directly
- * (without additional copying), coupled with an input side that maintains a
- * logically consistent 'apparent' size (ie, bytes in + bytes avail is static
- * for the lifetime of the FIFO).
- *
- * DMA output transactions originate on a cache line boundary and can be
- * variably-sized. DMA output transactions can be retired out-of-order but
- * the FIFO will only advance the output in the original input sequence.
- * This means the FIFO will eventually stall if a transaction is never retired.
- *
- * Chunking the output side into cache line multiples means that some FIFO
- * memory is unused. For example, if all the avail input has been pended out,
- * then the in and out markers are re-aligned to the next cache line.
- * The maximum possible waste is
- *     (cache line alignment - 1) * (max outstanding dma transactions)
- * This potential waste requires additional hidden capacity within the FIFO
- * to be able to accept input while the 'apparent' size has not been reached.
- *
- * Additional cache lines (ie, guard area) are used to minimize DMA
- * fragmentation when wrapping at the end of the FIFO. Input is allowed into the
- * guard area, but the in and out FIFO markers are wrapped when DMA is pended.
- */
-
-#define DMA_FIFO_GUARD 3   /* # of cache lines to reserve for the guard area */
-
-struct dma_fifo {
-	unsigned int	 in;
-	unsigned int	 out;		/* updated when dma is pended         */
-	unsigned int	 done;		/* updated upon dma completion        */
-	struct {
-		unsigned corrupt:1;
-	};
-	int		 size;		/* 'apparent' size of fifo	      */
-	int		 guard;		/* ofs of guard area		      */
-	int		 capacity;	/* size + reserved                    */
-	int		 avail;		/* # of unused bytes in fifo          */
-	unsigned int	 align;		/* must be power of 2                 */
-	int		 tx_limit;	/* max # of bytes per dma transaction */
-	int		 open_limit;	/* max # of outstanding allowed       */
-	int		 open;		/* # of outstanding dma transactions  */
-	struct list_head pending;	/* fifo markers for outstanding dma   */
-	void		 *data;
-};
-
-struct dma_pending {
-	struct list_head link;
-	void		 *data;
-	unsigned int	 len;
-	unsigned int	 next;
-	unsigned int	 out;
-};
-
-static inline void dp_mark_completed(struct dma_pending *dp)
-{
-	dp->data += 1;
-}
-
-static inline bool dp_is_completed(struct dma_pending *dp)
-{
-	return (unsigned long)dp->data & 1UL;
-}
-
-void dma_fifo_init(struct dma_fifo *fifo);
-int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned int align,
-		   int tx_limit, int open_limit, gfp_t gfp_mask);
-void dma_fifo_free(struct dma_fifo *fifo);
-void dma_fifo_reset(struct dma_fifo *fifo);
-int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n);
-int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended);
-int dma_fifo_out_complete(struct dma_fifo *fifo,
-			  struct dma_pending *complete);
-
-/* returns the # of used bytes in the fifo */
-static inline int dma_fifo_level(struct dma_fifo *fifo)
-{
-	return fifo->size - fifo->avail;
-}
-
-/* returns the # of bytes ready for output in the fifo */
-static inline int dma_fifo_out_level(struct dma_fifo *fifo)
-{
-	return fifo->in - fifo->out;
-}
-
-/* returns the # of unused bytes in the fifo */
-static inline int dma_fifo_avail(struct dma_fifo *fifo)
-{
-	return fifo->avail;
-}
-
-/* returns true if fifo has max # of outstanding dmas */
-static inline bool dma_fifo_busy(struct dma_fifo *fifo)
-{
-	return fifo->open == fifo->open_limit;
-}
-
-/* changes the max size of dma returned from dma_fifo_out_pend() */
-static inline int dma_fifo_change_tx_limit(struct dma_fifo *fifo, int tx_limit)
-{
-	tx_limit = round_down(tx_limit, fifo->align);
-	fifo->tx_limit = max_t(int, tx_limit, fifo->align);
-	return 0;
-}
-
-#endif /* _DMA_FIFO_H_ */