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-rw-r--r--freebsd/sys/kern/tty_outq.c347
1 files changed, 347 insertions, 0 deletions
diff --git a/freebsd/sys/kern/tty_outq.c b/freebsd/sys/kern/tty_outq.c
new file mode 100644
index 00000000..b6bc96d5
--- /dev/null
+++ b/freebsd/sys/kern/tty_outq.c
@@ -0,0 +1,347 @@
+#include <machine/rtems-bsd-kernel-space.h>
+
+/*-
+ * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Portions of this software were developed under sponsorship from Snow
+ * B.V., the Netherlands.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <rtems/bsd/sys/param.h>
+#include <sys/kernel.h>
+#include <rtems/bsd/sys/lock.h>
+#include <sys/queue.h>
+#include <sys/systm.h>
+#include <sys/tty.h>
+#include <sys/uio.h>
+
+#include <vm/uma.h>
+
+/*
+ * TTY output queue buffering.
+ *
+ * The previous design of the TTY layer offered the so-called clists.
+ * These clists were used for both the input queues and the output
+ * queue. We don't use certain features on the output side, like quoting
+ * bits for parity marking and such. This mechanism is similar to the
+ * old clists, but only contains the features we need to buffer the
+ * output.
+ */
+
+struct ttyoutq_block {
+ struct ttyoutq_block *tob_next;
+ char tob_data[TTYOUTQ_DATASIZE];
+};
+
+static uma_zone_t ttyoutq_zone;
+
+#define TTYOUTQ_INSERT_TAIL(to, tob) do { \
+ if (to->to_end == 0) { \
+ tob->tob_next = to->to_firstblock; \
+ to->to_firstblock = tob; \
+ } else { \
+ tob->tob_next = to->to_lastblock->tob_next; \
+ to->to_lastblock->tob_next = tob; \
+ } \
+ to->to_nblocks++; \
+} while (0)
+
+#define TTYOUTQ_REMOVE_HEAD(to) do { \
+ to->to_firstblock = to->to_firstblock->tob_next; \
+ to->to_nblocks--; \
+} while (0)
+
+#define TTYOUTQ_RECYCLE(to, tob) do { \
+ if (to->to_quota <= to->to_nblocks) \
+ uma_zfree(ttyoutq_zone, tob); \
+ else \
+ TTYOUTQ_INSERT_TAIL(to, tob); \
+} while(0)
+
+void
+ttyoutq_flush(struct ttyoutq *to)
+{
+
+ to->to_begin = 0;
+ to->to_end = 0;
+}
+
+int
+ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size)
+{
+ struct ttyoutq_block *tob;
+
+ to->to_quota = howmany(size, TTYOUTQ_DATASIZE);
+
+ while (to->to_quota > to->to_nblocks) {
+ /*
+ * List is getting bigger.
+ * Add new blocks to the tail of the list.
+ *
+ * We must unlock the TTY temporarily, because we need
+ * to allocate memory. This won't be a problem, because
+ * in the worst case, another thread ends up here, which
+ * may cause us to allocate too many blocks, but this
+ * will be caught by the loop below.
+ */
+ tty_unlock(tp);
+ tob = uma_zalloc(ttyoutq_zone, M_WAITOK);
+ tty_lock(tp);
+
+ if (tty_gone(tp)) {
+ uma_zfree(ttyoutq_zone, tob);
+ return (ENXIO);
+ }
+
+ TTYOUTQ_INSERT_TAIL(to, tob);
+ }
+ return (0);
+}
+
+void
+ttyoutq_free(struct ttyoutq *to)
+{
+ struct ttyoutq_block *tob;
+
+ ttyoutq_flush(to);
+ to->to_quota = 0;
+
+ while ((tob = to->to_firstblock) != NULL) {
+ TTYOUTQ_REMOVE_HEAD(to);
+ uma_zfree(ttyoutq_zone, tob);
+ }
+
+ MPASS(to->to_nblocks == 0);
+}
+
+size_t
+ttyoutq_read(struct ttyoutq *to, void *buf, size_t len)
+{
+ char *cbuf = buf;
+
+ while (len > 0) {
+ struct ttyoutq_block *tob;
+ size_t cbegin, cend, clen;
+
+ /* See if there still is data. */
+ if (to->to_begin == to->to_end)
+ break;
+ tob = to->to_firstblock;
+ if (tob == NULL)
+ break;
+
+ /*
+ * The end address should be the lowest of these three:
+ * - The write pointer
+ * - The blocksize - we can't read beyond the block
+ * - The end address if we could perform the full read
+ */
+ cbegin = to->to_begin;
+ cend = MIN(MIN(to->to_end, to->to_begin + len),
+ TTYOUTQ_DATASIZE);
+ clen = cend - cbegin;
+
+ /* Copy the data out of the buffers. */
+ memcpy(cbuf, tob->tob_data + cbegin, clen);
+ cbuf += clen;
+ len -= clen;
+
+ if (cend == to->to_end) {
+ /* Read the complete queue. */
+ to->to_begin = 0;
+ to->to_end = 0;
+ } else if (cend == TTYOUTQ_DATASIZE) {
+ /* Read the block until the end. */
+ TTYOUTQ_REMOVE_HEAD(to);
+ to->to_begin = 0;
+ to->to_end -= TTYOUTQ_DATASIZE;
+ TTYOUTQ_RECYCLE(to, tob);
+ } else {
+ /* Read the block partially. */
+ to->to_begin += clen;
+ }
+ }
+
+ return (cbuf - (char *)buf);
+}
+
+/*
+ * An optimized version of ttyoutq_read() which can be used in pseudo
+ * TTY drivers to directly copy data from the outq to userspace, instead
+ * of buffering it.
+ *
+ * We can only copy data directly if we need to read the entire block
+ * back to the user, because we temporarily remove the block from the
+ * queue. Otherwise we need to copy it to a temporary buffer first, to
+ * make sure data remains in the correct order.
+ */
+int
+ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio)
+{
+
+ while (uio->uio_resid > 0) {
+ int error;
+ struct ttyoutq_block *tob;
+ size_t cbegin, cend, clen;
+
+ /* See if there still is data. */
+ if (to->to_begin == to->to_end)
+ return (0);
+ tob = to->to_firstblock;
+ if (tob == NULL)
+ return (0);
+
+ /*
+ * The end address should be the lowest of these three:
+ * - The write pointer
+ * - The blocksize - we can't read beyond the block
+ * - The end address if we could perform the full read
+ */
+ cbegin = to->to_begin;
+ cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid),
+ TTYOUTQ_DATASIZE);
+ clen = cend - cbegin;
+
+ /*
+ * We can prevent buffering in some cases:
+ * - We need to read the block until the end.
+ * - We don't need to read the block until the end, but
+ * there is no data beyond it, which allows us to move
+ * the write pointer to a new block.
+ */
+ if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) {
+ /*
+ * Fast path: zero copy. Remove the first block,
+ * so we can unlock the TTY temporarily.
+ */
+ TTYOUTQ_REMOVE_HEAD(to);
+ to->to_begin = 0;
+ if (to->to_end <= TTYOUTQ_DATASIZE)
+ to->to_end = 0;
+ else
+ to->to_end -= TTYOUTQ_DATASIZE;
+
+ /* Temporary unlock and copy the data to userspace. */
+ tty_unlock(tp);
+ error = uiomove(tob->tob_data + cbegin, clen, uio);
+ tty_lock(tp);
+
+ /* Block can now be readded to the list. */
+ TTYOUTQ_RECYCLE(to, tob);
+ } else {
+ char ob[TTYOUTQ_DATASIZE - 1];
+
+ /*
+ * Slow path: store data in a temporary buffer.
+ */
+ memcpy(ob, tob->tob_data + cbegin, clen);
+ to->to_begin += clen;
+ MPASS(to->to_begin < TTYOUTQ_DATASIZE);
+
+ /* Temporary unlock and copy the data to userspace. */
+ tty_unlock(tp);
+ error = uiomove(ob, clen, uio);
+ tty_lock(tp);
+ }
+
+ if (error != 0)
+ return (error);
+ }
+
+ return (0);
+}
+
+size_t
+ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes)
+{
+ const char *cbuf = buf;
+ struct ttyoutq_block *tob;
+ unsigned int boff;
+ size_t l;
+
+ while (nbytes > 0) {
+ boff = to->to_end % TTYOUTQ_DATASIZE;
+
+ if (to->to_end == 0) {
+ /* First time we're being used or drained. */
+ MPASS(to->to_begin == 0);
+ tob = to->to_firstblock;
+ if (tob == NULL) {
+ /* Queue has no blocks. */
+ break;
+ }
+ to->to_lastblock = tob;
+ } else if (boff == 0) {
+ /* We reached the end of this block on last write. */
+ tob = to->to_lastblock->tob_next;
+ if (tob == NULL) {
+ /* We've reached the watermark. */
+ break;
+ }
+ to->to_lastblock = tob;
+ } else {
+ tob = to->to_lastblock;
+ }
+
+ /* Don't copy more than was requested. */
+ l = MIN(nbytes, TTYOUTQ_DATASIZE - boff);
+ MPASS(l > 0);
+ memcpy(tob->tob_data + boff, cbuf, l);
+
+ cbuf += l;
+ nbytes -= l;
+ to->to_end += l;
+ }
+
+ return (cbuf - (const char *)buf);
+}
+
+int
+ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes)
+{
+ size_t ret;
+
+ if (ttyoutq_bytesleft(to) < nbytes)
+ return (-1);
+
+ /* We should always be able to write it back. */
+ ret = ttyoutq_write(to, buf, nbytes);
+ MPASS(ret == nbytes);
+
+ return (0);
+}
+
+static void
+ttyoutq_startup(void *dummy)
+{
+
+ ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block),
+ NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
+}
+
+SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL);
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