da9dc13289
hvc_console is setting low_latency unconditionally, but some clients are interrupt driven and will call hvc_poll from irq context. This will cause tty_flip_buffer_push to be called from irq context, and it very clearly states it must not be called from IRQ when low_latency is specified. Looking back through history: v2.6.16-rc1 via33f0f88f1c
[PATCH] TTY layer buffering revamp added this new api. v2.6.16-rc3 via8977d929e4
[PATCH] tty buffering stall fix claims to fix a stall discovered with hvc_console v2.6.16-rc5 viafb5c594c2a
[PATCH] Fix race condition in hvc console. said set this flag to avoid a stall problem, and was merged through the powerpc arch tree. Without searching for email discussions, it would appear to be an overlapping "fix", but one that did not consider all users. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
912 lines
22 KiB
C
912 lines
22 KiB
C
/*
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* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
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* Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
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* Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
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* Copyright (C) 2004 IBM Corporation
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*
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* Additional Author(s):
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* Ryan S. Arnold <rsa@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/console.h>
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#include <linux/cpumask.h>
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#include <linux/init.h>
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#include <linux/kbd_kern.h>
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#include <linux/kernel.h>
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#include <linux/kthread.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/major.h>
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#include <linux/sysrq.h>
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/delay.h>
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#include <linux/freezer.h>
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#include <asm/uaccess.h>
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#include "hvc_console.h"
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#define HVC_MAJOR 229
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#define HVC_MINOR 0
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/*
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* Wait this long per iteration while trying to push buffered data to the
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* hypervisor before allowing the tty to complete a close operation.
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*/
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#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
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/*
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* These sizes are most efficient for vio, because they are the
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* native transfer size. We could make them selectable in the
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* future to better deal with backends that want other buffer sizes.
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*/
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#define N_OUTBUF 16
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#define N_INBUF 16
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#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
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static struct tty_driver *hvc_driver;
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static struct task_struct *hvc_task;
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/* Picks up late kicks after list walk but before schedule() */
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static int hvc_kicked;
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static int hvc_init(void);
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#ifdef CONFIG_MAGIC_SYSRQ
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static int sysrq_pressed;
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#endif
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/* dynamic list of hvc_struct instances */
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static LIST_HEAD(hvc_structs);
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/*
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* Protect the list of hvc_struct instances from inserts and removals during
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* list traversal.
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*/
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static DEFINE_SPINLOCK(hvc_structs_lock);
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/*
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* This value is used to assign a tty->index value to a hvc_struct based
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* upon order of exposure via hvc_probe(), when we can not match it to
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* a console candidate registered with hvc_instantiate().
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*/
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static int last_hvc = -1;
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/*
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* Do not call this function with either the hvc_structs_lock or the hvc_struct
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* lock held. If successful, this function increments the kref reference
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* count against the target hvc_struct so it should be released when finished.
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*/
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static struct hvc_struct *hvc_get_by_index(int index)
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{
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struct hvc_struct *hp;
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unsigned long flags;
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spin_lock(&hvc_structs_lock);
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list_for_each_entry(hp, &hvc_structs, next) {
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spin_lock_irqsave(&hp->lock, flags);
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if (hp->index == index) {
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kref_get(&hp->kref);
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spin_unlock_irqrestore(&hp->lock, flags);
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spin_unlock(&hvc_structs_lock);
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return hp;
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}
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spin_unlock_irqrestore(&hp->lock, flags);
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}
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hp = NULL;
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spin_unlock(&hvc_structs_lock);
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return hp;
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}
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/*
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* Initial console vtermnos for console API usage prior to full console
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* initialization. Any vty adapter outside this range will not have usable
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* console interfaces but can still be used as a tty device. This has to be
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* static because kmalloc will not work during early console init.
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*/
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static struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
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static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
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{[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
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/*
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* Console APIs, NOT TTY. These APIs are available immediately when
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* hvc_console_setup() finds adapters.
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*/
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static void hvc_console_print(struct console *co, const char *b,
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unsigned count)
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{
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char c[N_OUTBUF] __ALIGNED__;
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unsigned i = 0, n = 0;
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int r, donecr = 0, index = co->index;
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/* Console access attempt outside of acceptable console range. */
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if (index >= MAX_NR_HVC_CONSOLES)
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return;
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/* This console adapter was removed so it is not usable. */
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if (vtermnos[index] < 0)
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return;
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while (count > 0 || i > 0) {
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if (count > 0 && i < sizeof(c)) {
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if (b[n] == '\n' && !donecr) {
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c[i++] = '\r';
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donecr = 1;
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} else {
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c[i++] = b[n++];
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donecr = 0;
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--count;
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}
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} else {
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r = cons_ops[index]->put_chars(vtermnos[index], c, i);
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if (r <= 0) {
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/* throw away chars on error */
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i = 0;
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} else if (r > 0) {
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i -= r;
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if (i > 0)
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memmove(c, c+r, i);
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}
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}
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}
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}
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static struct tty_driver *hvc_console_device(struct console *c, int *index)
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{
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if (vtermnos[c->index] == -1)
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return NULL;
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*index = c->index;
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return hvc_driver;
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}
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static int __init hvc_console_setup(struct console *co, char *options)
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{
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if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
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return -ENODEV;
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if (vtermnos[co->index] == -1)
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return -ENODEV;
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return 0;
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}
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static struct console hvc_con_driver = {
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.name = "hvc",
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.write = hvc_console_print,
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.device = hvc_console_device,
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.setup = hvc_console_setup,
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.flags = CON_PRINTBUFFER,
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.index = -1,
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};
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/*
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* Early console initialization. Precedes driver initialization.
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*
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* (1) we are first, and the user specified another driver
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* -- index will remain -1
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* (2) we are first and the user specified no driver
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* -- index will be set to 0, then we will fail setup.
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* (3) we are first and the user specified our driver
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* -- index will be set to user specified driver, and we will fail
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* (4) we are after driver, and this initcall will register us
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* -- if the user didn't specify a driver then the console will match
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*
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* Note that for cases 2 and 3, we will match later when the io driver
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* calls hvc_instantiate() and call register again.
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*/
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static int __init hvc_console_init(void)
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{
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register_console(&hvc_con_driver);
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return 0;
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}
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console_initcall(hvc_console_init);
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/* callback when the kboject ref count reaches zero. */
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static void destroy_hvc_struct(struct kref *kref)
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{
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struct hvc_struct *hp = container_of(kref, struct hvc_struct, kref);
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unsigned long flags;
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spin_lock(&hvc_structs_lock);
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spin_lock_irqsave(&hp->lock, flags);
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list_del(&(hp->next));
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spin_unlock_irqrestore(&hp->lock, flags);
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spin_unlock(&hvc_structs_lock);
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kfree(hp);
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}
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/*
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* hvc_instantiate() is an early console discovery method which locates
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* consoles * prior to the vio subsystem discovering them. Hotplugged
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* vty adapters do NOT get an hvc_instantiate() callback since they
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* appear after early console init.
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*/
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int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
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{
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struct hvc_struct *hp;
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if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
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return -1;
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if (vtermnos[index] != -1)
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return -1;
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/* make sure no no tty has been registered in this index */
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hp = hvc_get_by_index(index);
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if (hp) {
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kref_put(&hp->kref, destroy_hvc_struct);
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return -1;
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}
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vtermnos[index] = vtermno;
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cons_ops[index] = ops;
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/* reserve all indices up to and including this index */
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if (last_hvc < index)
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last_hvc = index;
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/* if this index is what the user requested, then register
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* now (setup won't fail at this point). It's ok to just
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* call register again if previously .setup failed.
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*/
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if (index == hvc_con_driver.index)
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register_console(&hvc_con_driver);
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return 0;
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}
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EXPORT_SYMBOL_GPL(hvc_instantiate);
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/* Wake the sleeping khvcd */
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void hvc_kick(void)
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{
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hvc_kicked = 1;
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wake_up_process(hvc_task);
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}
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EXPORT_SYMBOL_GPL(hvc_kick);
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static void hvc_unthrottle(struct tty_struct *tty)
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{
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hvc_kick();
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}
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/*
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* The TTY interface won't be used until after the vio layer has exposed the vty
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* adapter to the kernel.
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*/
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static int hvc_open(struct tty_struct *tty, struct file * filp)
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{
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struct hvc_struct *hp;
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unsigned long flags;
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int rc = 0;
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/* Auto increments kref reference if found. */
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if (!(hp = hvc_get_by_index(tty->index)))
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return -ENODEV;
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spin_lock_irqsave(&hp->lock, flags);
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/* Check and then increment for fast path open. */
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if (hp->count++ > 0) {
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spin_unlock_irqrestore(&hp->lock, flags);
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hvc_kick();
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return 0;
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} /* else count == 0 */
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tty->driver_data = hp;
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if (!hp->irq_requested)
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tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
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hp->tty = tty;
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spin_unlock_irqrestore(&hp->lock, flags);
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if (hp->ops->notifier_add)
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rc = hp->ops->notifier_add(hp, hp->data);
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/*
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* If the notifier fails we return an error. The tty layer
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* will call hvc_close() after a failed open but we don't want to clean
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* up there so we'll clean up here and clear out the previously set
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* tty fields and return the kref reference.
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*/
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if (rc) {
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spin_lock_irqsave(&hp->lock, flags);
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hp->tty = NULL;
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spin_unlock_irqrestore(&hp->lock, flags);
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tty->driver_data = NULL;
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kref_put(&hp->kref, destroy_hvc_struct);
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printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
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}
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/* Force wakeup of the polling thread */
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hvc_kick();
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return rc;
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}
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static void hvc_close(struct tty_struct *tty, struct file * filp)
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{
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struct hvc_struct *hp;
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unsigned long flags;
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if (tty_hung_up_p(filp))
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return;
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/*
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* No driver_data means that this close was issued after a failed
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* hvc_open by the tty layer's release_dev() function and we can just
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* exit cleanly because the kref reference wasn't made.
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*/
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if (!tty->driver_data)
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return;
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hp = tty->driver_data;
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spin_lock_irqsave(&hp->lock, flags);
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if (--hp->count == 0) {
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/* We are done with the tty pointer now. */
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hp->tty = NULL;
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spin_unlock_irqrestore(&hp->lock, flags);
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if (hp->ops->notifier_del)
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hp->ops->notifier_del(hp, hp->data);
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/* cancel pending tty resize work */
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cancel_work_sync(&hp->tty_resize);
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/*
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* Chain calls chars_in_buffer() and returns immediately if
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* there is no buffered data otherwise sleeps on a wait queue
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* waking periodically to check chars_in_buffer().
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*/
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tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
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} else {
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if (hp->count < 0)
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printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
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hp->vtermno, hp->count);
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spin_unlock_irqrestore(&hp->lock, flags);
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}
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kref_put(&hp->kref, destroy_hvc_struct);
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}
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static void hvc_hangup(struct tty_struct *tty)
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{
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struct hvc_struct *hp = tty->driver_data;
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unsigned long flags;
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int temp_open_count;
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if (!hp)
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return;
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/* cancel pending tty resize work */
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cancel_work_sync(&hp->tty_resize);
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spin_lock_irqsave(&hp->lock, flags);
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/*
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* The N_TTY line discipline has problems such that in a close vs
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* open->hangup case this can be called after the final close so prevent
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* that from happening for now.
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*/
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if (hp->count <= 0) {
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spin_unlock_irqrestore(&hp->lock, flags);
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return;
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}
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temp_open_count = hp->count;
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hp->count = 0;
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hp->n_outbuf = 0;
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hp->tty = NULL;
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spin_unlock_irqrestore(&hp->lock, flags);
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if (hp->ops->notifier_hangup)
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hp->ops->notifier_hangup(hp, hp->data);
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while(temp_open_count) {
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--temp_open_count;
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kref_put(&hp->kref, destroy_hvc_struct);
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}
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}
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/*
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* Push buffered characters whether they were just recently buffered or waiting
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* on a blocked hypervisor. Call this function with hp->lock held.
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*/
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static int hvc_push(struct hvc_struct *hp)
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{
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int n;
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n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
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if (n <= 0) {
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if (n == 0) {
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hp->do_wakeup = 1;
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return 0;
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}
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/* throw away output on error; this happens when
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there is no session connected to the vterm. */
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hp->n_outbuf = 0;
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} else
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hp->n_outbuf -= n;
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if (hp->n_outbuf > 0)
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memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
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else
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hp->do_wakeup = 1;
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return n;
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}
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static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
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{
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struct hvc_struct *hp = tty->driver_data;
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unsigned long flags;
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int rsize, written = 0;
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/* This write was probably executed during a tty close. */
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if (!hp)
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return -EPIPE;
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if (hp->count <= 0)
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return -EIO;
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spin_lock_irqsave(&hp->lock, flags);
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/* Push pending writes */
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if (hp->n_outbuf > 0)
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hvc_push(hp);
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while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
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if (rsize > count)
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rsize = count;
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memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
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count -= rsize;
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buf += rsize;
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hp->n_outbuf += rsize;
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written += rsize;
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hvc_push(hp);
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}
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spin_unlock_irqrestore(&hp->lock, flags);
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/*
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* Racy, but harmless, kick thread if there is still pending data.
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*/
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if (hp->n_outbuf)
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hvc_kick();
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return written;
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}
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/**
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* hvc_set_winsz() - Resize the hvc tty terminal window.
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* @work: work structure.
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*
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* The routine shall not be called within an atomic context because it
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* might sleep.
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*
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* Locking: hp->lock
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*/
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static void hvc_set_winsz(struct work_struct *work)
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{
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struct hvc_struct *hp;
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unsigned long hvc_flags;
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struct tty_struct *tty;
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struct winsize ws;
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hp = container_of(work, struct hvc_struct, tty_resize);
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if (!hp)
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|
return;
|
|
|
|
spin_lock_irqsave(&hp->lock, hvc_flags);
|
|
if (!hp->tty) {
|
|
spin_unlock_irqrestore(&hp->lock, hvc_flags);
|
|
return;
|
|
}
|
|
ws = hp->ws;
|
|
tty = tty_kref_get(hp->tty);
|
|
spin_unlock_irqrestore(&hp->lock, hvc_flags);
|
|
|
|
tty_do_resize(tty, &ws);
|
|
tty_kref_put(tty);
|
|
}
|
|
|
|
/*
|
|
* This is actually a contract between the driver and the tty layer outlining
|
|
* how much write room the driver can guarantee will be sent OR BUFFERED. This
|
|
* driver MUST honor the return value.
|
|
*/
|
|
static int hvc_write_room(struct tty_struct *tty)
|
|
{
|
|
struct hvc_struct *hp = tty->driver_data;
|
|
|
|
if (!hp)
|
|
return -1;
|
|
|
|
return hp->outbuf_size - hp->n_outbuf;
|
|
}
|
|
|
|
static int hvc_chars_in_buffer(struct tty_struct *tty)
|
|
{
|
|
struct hvc_struct *hp = tty->driver_data;
|
|
|
|
if (!hp)
|
|
return -1;
|
|
return hp->n_outbuf;
|
|
}
|
|
|
|
/*
|
|
* timeout will vary between the MIN and MAX values defined here. By default
|
|
* and during console activity we will use a default MIN_TIMEOUT of 10. When
|
|
* the console is idle, we increase the timeout value on each pass through
|
|
* msleep until we reach the max. This may be noticeable as a brief (average
|
|
* one second) delay on the console before the console responds to input when
|
|
* there has been no input for some time.
|
|
*/
|
|
#define MIN_TIMEOUT (10)
|
|
#define MAX_TIMEOUT (2000)
|
|
static u32 timeout = MIN_TIMEOUT;
|
|
|
|
#define HVC_POLL_READ 0x00000001
|
|
#define HVC_POLL_WRITE 0x00000002
|
|
|
|
int hvc_poll(struct hvc_struct *hp)
|
|
{
|
|
struct tty_struct *tty;
|
|
int i, n, poll_mask = 0;
|
|
char buf[N_INBUF] __ALIGNED__;
|
|
unsigned long flags;
|
|
int read_total = 0;
|
|
int written_total = 0;
|
|
|
|
spin_lock_irqsave(&hp->lock, flags);
|
|
|
|
/* Push pending writes */
|
|
if (hp->n_outbuf > 0)
|
|
written_total = hvc_push(hp);
|
|
|
|
/* Reschedule us if still some write pending */
|
|
if (hp->n_outbuf > 0) {
|
|
poll_mask |= HVC_POLL_WRITE;
|
|
/* If hvc_push() was not able to write, sleep a few msecs */
|
|
timeout = (written_total) ? 0 : MIN_TIMEOUT;
|
|
}
|
|
|
|
/* No tty attached, just skip */
|
|
tty = hp->tty;
|
|
if (tty == NULL)
|
|
goto bail;
|
|
|
|
/* Now check if we can get data (are we throttled ?) */
|
|
if (test_bit(TTY_THROTTLED, &tty->flags))
|
|
goto throttled;
|
|
|
|
/* If we aren't notifier driven and aren't throttled, we always
|
|
* request a reschedule
|
|
*/
|
|
if (!hp->irq_requested)
|
|
poll_mask |= HVC_POLL_READ;
|
|
|
|
/* Read data if any */
|
|
for (;;) {
|
|
int count = tty_buffer_request_room(tty, N_INBUF);
|
|
|
|
/* If flip is full, just reschedule a later read */
|
|
if (count == 0) {
|
|
poll_mask |= HVC_POLL_READ;
|
|
break;
|
|
}
|
|
|
|
n = hp->ops->get_chars(hp->vtermno, buf, count);
|
|
if (n <= 0) {
|
|
/* Hangup the tty when disconnected from host */
|
|
if (n == -EPIPE) {
|
|
spin_unlock_irqrestore(&hp->lock, flags);
|
|
tty_hangup(tty);
|
|
spin_lock_irqsave(&hp->lock, flags);
|
|
} else if ( n == -EAGAIN ) {
|
|
/*
|
|
* Some back-ends can only ensure a certain min
|
|
* num of bytes read, which may be > 'count'.
|
|
* Let the tty clear the flip buff to make room.
|
|
*/
|
|
poll_mask |= HVC_POLL_READ;
|
|
}
|
|
break;
|
|
}
|
|
for (i = 0; i < n; ++i) {
|
|
#ifdef CONFIG_MAGIC_SYSRQ
|
|
if (hp->index == hvc_con_driver.index) {
|
|
/* Handle the SysRq Hack */
|
|
/* XXX should support a sequence */
|
|
if (buf[i] == '\x0f') { /* ^O */
|
|
/* if ^O is pressed again, reset
|
|
* sysrq_pressed and flip ^O char */
|
|
sysrq_pressed = !sysrq_pressed;
|
|
if (sysrq_pressed)
|
|
continue;
|
|
} else if (sysrq_pressed) {
|
|
handle_sysrq(buf[i], tty);
|
|
sysrq_pressed = 0;
|
|
continue;
|
|
}
|
|
}
|
|
#endif /* CONFIG_MAGIC_SYSRQ */
|
|
tty_insert_flip_char(tty, buf[i], 0);
|
|
}
|
|
|
|
read_total += n;
|
|
}
|
|
throttled:
|
|
/* Wakeup write queue if necessary */
|
|
if (hp->do_wakeup) {
|
|
hp->do_wakeup = 0;
|
|
tty_wakeup(tty);
|
|
}
|
|
bail:
|
|
spin_unlock_irqrestore(&hp->lock, flags);
|
|
|
|
if (read_total) {
|
|
/* Activity is occurring, so reset the polling backoff value to
|
|
a minimum for performance. */
|
|
timeout = MIN_TIMEOUT;
|
|
|
|
tty_flip_buffer_push(tty);
|
|
}
|
|
|
|
return poll_mask;
|
|
}
|
|
EXPORT_SYMBOL_GPL(hvc_poll);
|
|
|
|
/**
|
|
* hvc_resize() - Update terminal window size information.
|
|
* @hp: HVC console pointer
|
|
* @ws: Terminal window size structure
|
|
*
|
|
* Stores the specified window size information in the hvc structure of @hp.
|
|
* The function schedule the tty resize update.
|
|
*
|
|
* Locking: Locking free; the function MUST be called holding hp->lock
|
|
*/
|
|
void hvc_resize(struct hvc_struct *hp, struct winsize ws)
|
|
{
|
|
hp->ws = ws;
|
|
schedule_work(&hp->tty_resize);
|
|
}
|
|
EXPORT_SYMBOL_GPL(hvc_resize);
|
|
|
|
/*
|
|
* This kthread is either polling or interrupt driven. This is determined by
|
|
* calling hvc_poll() who determines whether a console adapter support
|
|
* interrupts.
|
|
*/
|
|
static int khvcd(void *unused)
|
|
{
|
|
int poll_mask;
|
|
struct hvc_struct *hp;
|
|
|
|
set_freezable();
|
|
__set_current_state(TASK_RUNNING);
|
|
do {
|
|
poll_mask = 0;
|
|
hvc_kicked = 0;
|
|
try_to_freeze();
|
|
wmb();
|
|
if (!cpus_are_in_xmon()) {
|
|
spin_lock(&hvc_structs_lock);
|
|
list_for_each_entry(hp, &hvc_structs, next) {
|
|
poll_mask |= hvc_poll(hp);
|
|
}
|
|
spin_unlock(&hvc_structs_lock);
|
|
} else
|
|
poll_mask |= HVC_POLL_READ;
|
|
if (hvc_kicked)
|
|
continue;
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
if (!hvc_kicked) {
|
|
if (poll_mask == 0)
|
|
schedule();
|
|
else {
|
|
if (timeout < MAX_TIMEOUT)
|
|
timeout += (timeout >> 6) + 1;
|
|
|
|
msleep_interruptible(timeout);
|
|
}
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
} while (!kthread_should_stop());
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct tty_operations hvc_ops = {
|
|
.open = hvc_open,
|
|
.close = hvc_close,
|
|
.write = hvc_write,
|
|
.hangup = hvc_hangup,
|
|
.unthrottle = hvc_unthrottle,
|
|
.write_room = hvc_write_room,
|
|
.chars_in_buffer = hvc_chars_in_buffer,
|
|
};
|
|
|
|
struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int data,
|
|
struct hv_ops *ops, int outbuf_size)
|
|
{
|
|
struct hvc_struct *hp;
|
|
int i;
|
|
|
|
/* We wait until a driver actually comes along */
|
|
if (!hvc_driver) {
|
|
int err = hvc_init();
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
hp = kmalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
|
|
GFP_KERNEL);
|
|
if (!hp)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
memset(hp, 0x00, sizeof(*hp));
|
|
|
|
hp->vtermno = vtermno;
|
|
hp->data = data;
|
|
hp->ops = ops;
|
|
hp->outbuf_size = outbuf_size;
|
|
hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
|
|
|
|
kref_init(&hp->kref);
|
|
|
|
INIT_WORK(&hp->tty_resize, hvc_set_winsz);
|
|
spin_lock_init(&hp->lock);
|
|
spin_lock(&hvc_structs_lock);
|
|
|
|
/*
|
|
* find index to use:
|
|
* see if this vterm id matches one registered for console.
|
|
*/
|
|
for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
|
|
if (vtermnos[i] == hp->vtermno &&
|
|
cons_ops[i] == hp->ops)
|
|
break;
|
|
|
|
/* no matching slot, just use a counter */
|
|
if (i >= MAX_NR_HVC_CONSOLES)
|
|
i = ++last_hvc;
|
|
|
|
hp->index = i;
|
|
|
|
list_add_tail(&(hp->next), &hvc_structs);
|
|
spin_unlock(&hvc_structs_lock);
|
|
|
|
return hp;
|
|
}
|
|
EXPORT_SYMBOL_GPL(hvc_alloc);
|
|
|
|
int hvc_remove(struct hvc_struct *hp)
|
|
{
|
|
unsigned long flags;
|
|
struct tty_struct *tty;
|
|
|
|
spin_lock_irqsave(&hp->lock, flags);
|
|
tty = hp->tty;
|
|
|
|
if (hp->index < MAX_NR_HVC_CONSOLES)
|
|
vtermnos[hp->index] = -1;
|
|
|
|
/* Don't whack hp->irq because tty_hangup() will need to free the irq. */
|
|
|
|
spin_unlock_irqrestore(&hp->lock, flags);
|
|
|
|
/*
|
|
* We 'put' the instance that was grabbed when the kref instance
|
|
* was initialized using kref_init(). Let the last holder of this
|
|
* kref cause it to be removed, which will probably be the tty_hangup
|
|
* below.
|
|
*/
|
|
kref_put(&hp->kref, destroy_hvc_struct);
|
|
|
|
/*
|
|
* This function call will auto chain call hvc_hangup. The tty should
|
|
* always be valid at this time unless a simultaneous tty close already
|
|
* cleaned up the hvc_struct.
|
|
*/
|
|
if (tty)
|
|
tty_hangup(tty);
|
|
return 0;
|
|
}
|
|
|
|
/* Driver initialization: called as soon as someone uses hvc_alloc(). */
|
|
static int hvc_init(void)
|
|
{
|
|
struct tty_driver *drv;
|
|
int err;
|
|
|
|
/* We need more than hvc_count adapters due to hotplug additions. */
|
|
drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
|
|
if (!drv) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
drv->owner = THIS_MODULE;
|
|
drv->driver_name = "hvc";
|
|
drv->name = "hvc";
|
|
drv->major = HVC_MAJOR;
|
|
drv->minor_start = HVC_MINOR;
|
|
drv->type = TTY_DRIVER_TYPE_SYSTEM;
|
|
drv->init_termios = tty_std_termios;
|
|
drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
|
|
tty_set_operations(drv, &hvc_ops);
|
|
|
|
/* Always start the kthread because there can be hotplug vty adapters
|
|
* added later. */
|
|
hvc_task = kthread_run(khvcd, NULL, "khvcd");
|
|
if (IS_ERR(hvc_task)) {
|
|
printk(KERN_ERR "Couldn't create kthread for console.\n");
|
|
err = PTR_ERR(hvc_task);
|
|
goto put_tty;
|
|
}
|
|
|
|
err = tty_register_driver(drv);
|
|
if (err) {
|
|
printk(KERN_ERR "Couldn't register hvc console driver\n");
|
|
goto stop_thread;
|
|
}
|
|
|
|
/*
|
|
* Make sure tty is fully registered before allowing it to be
|
|
* found by hvc_console_device.
|
|
*/
|
|
smp_mb();
|
|
hvc_driver = drv;
|
|
return 0;
|
|
|
|
stop_thread:
|
|
kthread_stop(hvc_task);
|
|
hvc_task = NULL;
|
|
put_tty:
|
|
put_tty_driver(drv);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/* This isn't particularly necessary due to this being a console driver
|
|
* but it is nice to be thorough.
|
|
*/
|
|
static void __exit hvc_exit(void)
|
|
{
|
|
if (hvc_driver) {
|
|
kthread_stop(hvc_task);
|
|
|
|
tty_unregister_driver(hvc_driver);
|
|
/* return tty_struct instances allocated in hvc_init(). */
|
|
put_tty_driver(hvc_driver);
|
|
unregister_console(&hvc_con_driver);
|
|
}
|
|
}
|
|
module_exit(hvc_exit);
|