/* * Copyright (C) 2001 Anton Blanchard , IBM * Copyright (C) 2001 Paul Mackerras , IBM * Copyright (C) 2004 Benjamin Herrenschmidt , IBM Corp. * Copyright (C) 2004 IBM Corporation * * Additional Author(s): * Ryan S. Arnold * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define HVC_MAJOR 229 #define HVC_MINOR 0 #define TIMEOUT (10) /* * Wait this long per iteration while trying to push buffered data to the * hypervisor before allowing the tty to complete a close operation. */ #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */ /* * The Linux TTY code does not support dynamic addition of tty derived devices * so we need to know how many tty devices we might need when space is allocated * for the tty device. Since this driver supports hotplug of vty adapters we * need to make sure we have enough allocated. */ #define HVC_ALLOC_TTY_ADAPTERS 8 #define N_OUTBUF 16 #define N_INBUF 16 #define __ALIGNED__ __attribute__((__aligned__(8))) static struct tty_driver *hvc_driver; static struct task_struct *hvc_task; /* Picks up late kicks after list walk but before schedule() */ static int hvc_kicked; #ifdef CONFIG_MAGIC_SYSRQ static int sysrq_pressed; #endif struct hvc_struct { spinlock_t lock; int index; struct tty_struct *tty; unsigned int count; int do_wakeup; char outbuf[N_OUTBUF] __ALIGNED__; int n_outbuf; uint32_t vtermno; int irq_requested; int irq; struct list_head next; struct kobject kobj; /* ref count & hvc_struct lifetime */ }; /* dynamic list of hvc_struct instances */ static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs); /* * Protect the list of hvc_struct instances from inserts and removals during * list traversal. */ static DEFINE_SPINLOCK(hvc_structs_lock); /* * This value is used to assign a tty->index value to a hvc_struct based * upon order of exposure via hvc_probe(), when we can not match it to * a console canidate registered with hvc_instantiate(). */ static int last_hvc = -1; /* * Do not call this function with either the hvc_strucst_lock or the hvc_struct * lock held. If successful, this function increments the kobject reference * count against the target hvc_struct so it should be released when finished. */ struct hvc_struct *hvc_get_by_index(int index) { struct hvc_struct *hp; unsigned long flags; spin_lock(&hvc_structs_lock); list_for_each_entry(hp, &hvc_structs, next) { spin_lock_irqsave(&hp->lock, flags); if (hp->index == index) { kobject_get(&hp->kobj); spin_unlock_irqrestore(&hp->lock, flags); spin_unlock(&hvc_structs_lock); return hp; } spin_unlock_irqrestore(&hp->lock, flags); } hp = NULL; spin_unlock(&hvc_structs_lock); return hp; } /* * Initial console vtermnos for console API usage prior to full console * initialization. Any vty adapter outside this range will not have usable * console interfaces but can still be used as a tty device. This has to be * static because kmalloc will not work during early console init. */ static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] = {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1}; /* * Console APIs, NOT TTY. These APIs are available immediately when * hvc_console_setup() finds adapters. */ void hvc_console_print(struct console *co, const char *b, unsigned count) { char c[16] __ALIGNED__; unsigned i = 0, n = 0; int r, donecr = 0; /* Console access attempt outside of acceptable console range. */ if (co->index >= MAX_NR_HVC_CONSOLES) return; /* This console adapter was removed so it is not useable. */ if (vtermnos[co->index] < 0) return; while (count > 0 || i > 0) { if (count > 0 && i < sizeof(c)) { if (b[n] == '\n' && !donecr) { c[i++] = '\r'; donecr = 1; } else { c[i++] = b[n++]; donecr = 0; --count; } } else { r = hvc_put_chars(vtermnos[co->index], c, i); if (r < 0) { /* throw away chars on error */ i = 0; } else if (r > 0) { i -= r; if (i > 0) memmove(c, c+r, i); } } } } static struct tty_driver *hvc_console_device(struct console *c, int *index) { if (vtermnos[c->index] == -1) return NULL; *index = c->index; return hvc_driver; } static int __init hvc_console_setup(struct console *co, char *options) { if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES) return -ENODEV; if (vtermnos[co->index] == -1) return -ENODEV; return 0; } struct console hvc_con_driver = { .name = "hvc", .write = hvc_console_print, .device = hvc_console_device, .setup = hvc_console_setup, .flags = CON_PRINTBUFFER, .index = -1, }; /* * Early console initialization. Preceeds driver initialization. * * (1) we are first, and the user specified another driver * -- index will remain -1 * (2) we are first and the user specified no driver * -- index will be set to 0, then we will fail setup. * (3) we are first and the user specified our driver * -- index will be set to user specified driver, and we will fail * (4) we are after driver, and this initcall will register us * -- if the user didn't specify a driver then the console will match * * Note that for cases 2 and 3, we will match later when the io driver * calls hvc_instantiate() and call register again. */ static int __init hvc_console_init(void) { register_console(&hvc_con_driver); return 0; } console_initcall(hvc_console_init); /* * hvc_instantiate() is an early console discovery method which locates * consoles * prior to the vio subsystem discovering them. Hotplugged * vty adapters do NOT get an hvc_instantiate() callback since they * appear after early console init. */ int hvc_instantiate(uint32_t vtermno, int index) { struct hvc_struct *hp; if (index < 0 || index >= MAX_NR_HVC_CONSOLES) return -1; if (vtermnos[index] != -1) return -1; /* make sure no no tty has been registerd in this index */ hp = hvc_get_by_index(index); if (hp) { kobject_put(&hp->kobj); return -1; } vtermnos[index] = vtermno; /* reserve all indices upto and including this index */ if (last_hvc < index) last_hvc = index; /* if this index is what the user requested, then register * now (setup won't fail at this point). It's ok to just * call register again if previously .setup failed. */ if (index == hvc_con_driver.index) register_console(&hvc_con_driver); return 0; } EXPORT_SYMBOL(hvc_instantiate); /* Wake the sleeping khvcd */ static void hvc_kick(void) { hvc_kicked = 1; wake_up_process(hvc_task); } static int hvc_poll(struct hvc_struct *hp); /* * NOTE: This API isn't used if the console adapter doesn't support interrupts. * In this case the console is poll driven. */ static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs) { /* if hvc_poll request a repoll, then kick the hvcd thread */ if (hvc_poll(dev_instance)) hvc_kick(); return IRQ_HANDLED; } static void hvc_unthrottle(struct tty_struct *tty) { hvc_kick(); } /* * The TTY interface won't be used until after the vio layer has exposed the vty * adapter to the kernel. */ static int hvc_open(struct tty_struct *tty, struct file * filp) { struct hvc_struct *hp; unsigned long flags; int irq = NO_IRQ; int rc = 0; struct kobject *kobjp; /* Auto increments kobject reference if found. */ if (!(hp = hvc_get_by_index(tty->index))) { printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n"); return -ENODEV; } spin_lock_irqsave(&hp->lock, flags); /* Check and then increment for fast path open. */ if (hp->count++ > 0) { spin_unlock_irqrestore(&hp->lock, flags); hvc_kick(); return 0; } /* else count == 0 */ tty->driver_data = hp; hp->tty = tty; /* Save for request_irq outside of spin_lock. */ irq = hp->irq; if (irq != NO_IRQ) hp->irq_requested = 1; kobjp = &hp->kobj; spin_unlock_irqrestore(&hp->lock, flags); /* check error, fallback to non-irq */ if (irq != NO_IRQ) rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp); /* * If the request_irq() fails and we return an error. The tty layer * will call hvc_close() after a failed open but we don't want to clean * up there so we'll clean up here and clear out the previously set * tty fields and return the kobject reference. */ if (rc) { spin_lock_irqsave(&hp->lock, flags); hp->tty = NULL; hp->irq_requested = 0; spin_unlock_irqrestore(&hp->lock, flags); tty->driver_data = NULL; kobject_put(kobjp); printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc); } /* Force wakeup of the polling thread */ hvc_kick(); return rc; } static void hvc_close(struct tty_struct *tty, struct file * filp) { struct hvc_struct *hp; struct kobject *kobjp; int irq = NO_IRQ; unsigned long flags; if (tty_hung_up_p(filp)) return; /* * No driver_data means that this close was issued after a failed * hvc_open by the tty layer's release_dev() function and we can just * exit cleanly because the kobject reference wasn't made. */ if (!tty->driver_data) return; hp = tty->driver_data; spin_lock_irqsave(&hp->lock, flags); kobjp = &hp->kobj; if (--hp->count == 0) { if (hp->irq_requested) irq = hp->irq; hp->irq_requested = 0; /* We are done with the tty pointer now. */ hp->tty = NULL; spin_unlock_irqrestore(&hp->lock, flags); /* * Chain calls chars_in_buffer() and returns immediately if * there is no buffered data otherwise sleeps on a wait queue * waking periodically to check chars_in_buffer(). */ tty_wait_until_sent(tty, HVC_CLOSE_WAIT); if (irq != NO_IRQ) free_irq(irq, hp); } else { if (hp->count < 0) printk(KERN_ERR "hvc_close %X: oops, count is %d\n", hp->vtermno, hp->count); spin_unlock_irqrestore(&hp->lock, flags); } kobject_put(kobjp); } static void hvc_hangup(struct tty_struct *tty) { struct hvc_struct *hp = tty->driver_data; unsigned long flags; int irq = NO_IRQ; int temp_open_count; struct kobject *kobjp; if (!hp) return; spin_lock_irqsave(&hp->lock, flags); /* * The N_TTY line discipline has problems such that in a close vs * open->hangup case this can be called after the final close so prevent * that from happening for now. */ if (hp->count <= 0) { spin_unlock_irqrestore(&hp->lock, flags); return; } kobjp = &hp->kobj; temp_open_count = hp->count; hp->count = 0; hp->n_outbuf = 0; hp->tty = NULL; if (hp->irq_requested) /* Saved for use outside of spin_lock. */ irq = hp->irq; hp->irq_requested = 0; spin_unlock_irqrestore(&hp->lock, flags); if (irq != NO_IRQ) free_irq(irq, hp); while(temp_open_count) { --temp_open_count; kobject_put(kobjp); } } /* * Push buffered characters whether they were just recently buffered or waiting * on a blocked hypervisor. Call this function with hp->lock held. */ static void hvc_push(struct hvc_struct *hp) { int n; n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf); if (n <= 0) { if (n == 0) return; /* throw away output on error; this happens when there is no session connected to the vterm. */ hp->n_outbuf = 0; } else hp->n_outbuf -= n; if (hp->n_outbuf > 0) memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf); else hp->do_wakeup = 1; } static inline int __hvc_write_kernel(struct hvc_struct *hp, const unsigned char *buf, int count) { unsigned long flags; int rsize, written = 0; spin_lock_irqsave(&hp->lock, flags); /* Push pending writes */ if (hp->n_outbuf > 0) hvc_push(hp); while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) { if (rsize > count) rsize = count; memcpy(hp->outbuf + hp->n_outbuf, buf, rsize); count -= rsize; buf += rsize; hp->n_outbuf += rsize; written += rsize; hvc_push(hp); } spin_unlock_irqrestore(&hp->lock, flags); return written; } static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count) { struct hvc_struct *hp = tty->driver_data; int written; /* This write was probably executed during a tty close. */ if (!hp) return -EPIPE; if (hp->count <= 0) return -EIO; written = __hvc_write_kernel(hp, buf, count); /* * Racy, but harmless, kick thread if there is still pending data. * There really is nothing wrong with kicking the thread, even if there * is no buffered data. */ if (hp->n_outbuf) hvc_kick(); return written; } /* * This is actually a contract between the driver and the tty layer outlining * how much write room the driver can guarentee 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 N_OUTBUF - 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; } #define HVC_POLL_READ 0x00000001 #define HVC_POLL_WRITE 0x00000002 #define HVC_POLL_QUICK 0x00000004 static 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; spin_lock_irqsave(&hp->lock, flags); /* Push pending writes */ if (hp->n_outbuf > 0) hvc_push(hp); /* Reschedule us if still some write pending */ if (hp->n_outbuf > 0) poll_mask |= HVC_POLL_WRITE; /* 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 interrupt driven and aren't throttled, we always * request a reschedule */ if (hp->irq == NO_IRQ) poll_mask |= HVC_POLL_READ; /* Read data if any */ for (;;) { int count = N_INBUF; if (count > (TTY_FLIPBUF_SIZE - tty->flip.count)) count = TTY_FLIPBUF_SIZE - tty->flip.count; /* If flip is full, just reschedule a later read */ if (count == 0) { poll_mask |= HVC_POLL_READ; break; } n = hvc_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); } 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 */ sysrq_pressed = 1; continue; } else if (sysrq_pressed) { handle_sysrq(buf[i], NULL, tty); sysrq_pressed = 0; continue; } } #endif /* CONFIG_MAGIC_SYSRQ */ tty_insert_flip_char(tty, buf[i], 0); } if (tty->flip.count) tty_schedule_flip(tty); /* * Account for the total amount read in one loop, and if above * 64 bytes, we do a quick schedule loop to let the tty grok * the data and eventually throttle us. */ read_total += n; if (read_total >= 64) { poll_mask |= HVC_POLL_QUICK; break; } } throttled: /* Wakeup write queue if necessary */ if (hp->do_wakeup) { hp->do_wakeup = 0; tty_wakeup(tty); } bail: spin_unlock_irqrestore(&hp->lock, flags); return poll_mask; } #if defined(CONFIG_XMON) && defined(CONFIG_SMP) extern cpumask_t cpus_in_xmon; #else static const cpumask_t cpus_in_xmon = CPU_MASK_NONE; #endif /* * This kthread is either polling or interrupt driven. This is determined by * calling hvc_poll() who determines whether a console adapter support * interrupts. */ int khvcd(void *unused) { int poll_mask; struct hvc_struct *hp; __set_current_state(TASK_RUNNING); do { poll_mask = 0; hvc_kicked = 0; wmb(); if (cpus_empty(cpus_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; if (poll_mask & HVC_POLL_QUICK) { yield(); continue; } set_current_state(TASK_INTERRUPTIBLE); if (!hvc_kicked) { if (poll_mask == 0) schedule(); else msleep_interruptible(TIMEOUT); } __set_current_state(TASK_RUNNING); } while (!kthread_should_stop()); return 0; } static 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, }; /* callback when the kboject ref count reaches zero. */ static void destroy_hvc_struct(struct kobject *kobj) { struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj); unsigned long flags; spin_lock(&hvc_structs_lock); spin_lock_irqsave(&hp->lock, flags); list_del(&(hp->next)); spin_unlock_irqrestore(&hp->lock, flags); spin_unlock(&hvc_structs_lock); kfree(hp); } static struct kobj_type hvc_kobj_type = { .release = destroy_hvc_struct, }; struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq) { struct hvc_struct *hp; int i; hp = kmalloc(sizeof(*hp), GFP_KERNEL); if (!hp) return ERR_PTR(-ENOMEM); memset(hp, 0x00, sizeof(*hp)); hp->vtermno = vtermno; hp->irq = irq; kobject_init(&hp->kobj); hp->kobj.ktype = &hvc_kobj_type; 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) 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(hvc_alloc); int __devexit hvc_remove(struct hvc_struct *hp) { unsigned long flags; struct kobject *kobjp; struct tty_struct *tty; spin_lock_irqsave(&hp->lock, flags); tty = hp->tty; kobjp = &hp->kobj; 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 kobject instance * was intialized using kobject_init(). Let the last holder of this * kobject cause it to be removed, which will probably be the tty_hangup * below. */ kobject_put(kobjp); /* * 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; } EXPORT_SYMBOL(hvc_remove); /* Driver initialization. Follow console initialization. This is where the TTY * interfaces start to become available. */ int __init hvc_init(void) { /* We need more than hvc_count adapters due to hotplug additions. */ hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS); if (!hvc_driver) return -ENOMEM; hvc_driver->owner = THIS_MODULE; hvc_driver->devfs_name = "hvc/"; hvc_driver->driver_name = "hvc"; hvc_driver->name = "hvc"; hvc_driver->major = HVC_MAJOR; hvc_driver->minor_start = HVC_MINOR; hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM; hvc_driver->init_termios = tty_std_termios; hvc_driver->flags = TTY_DRIVER_REAL_RAW; tty_set_operations(hvc_driver, &hvc_ops); if (tty_register_driver(hvc_driver)) panic("Couldn't register hvc console driver\n"); /* 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)) { panic("Couldn't create kthread for console.\n"); put_tty_driver(hvc_driver); return -EIO; } return 0; } module_init(hvc_init); /* This isn't particularily necessary due to this being a console driver * but it is nice to be thorough. */ static void __exit hvc_exit(void) { 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);