diff options
Diffstat (limited to 'drivers/char/hvc_console.c')
| -rw-r--r-- | drivers/char/hvc_console.c | 831 |
1 files changed, 831 insertions, 0 deletions
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c new file mode 100644 index 000000000000..88cd858f74d0 --- /dev/null +++ b/drivers/char/hvc_console.c @@ -0,0 +1,831 @@ +/* + * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM + * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM + * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp. + * Copyright (C) 2004 IBM Corporation + * + * Additional Author(s): + * Ryan S. Arnold <rsa@us.ibm.com> + * + * 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 <linux/console.h> +#include <linux/cpumask.h> +#include <linux/init.h> +#include <linux/kbd_kern.h> +#include <linux/kernel.h> +#include <linux/kobject.h> +#include <linux/kthread.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/major.h> +#include <linux/sysrq.h> +#include <linux/tty.h> +#include <linux/tty_flip.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/delay.h> +#include <asm/uaccess.h> +#include <asm/hvconsole.h> +#include <asm/vio.h> + +#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 + +static struct tty_driver *hvc_driver; +#ifdef CONFIG_MAGIC_SYSRQ +static int sysrq_pressed; +#endif + +#define N_OUTBUF 16 +#define N_INBUF 16 + +#define __ALIGNED__ __attribute__((__aligned__(8))) + +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 */ + struct vio_dev *vdev; +}; + +/* 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); + +/* + * 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]; + +/* Used for accounting purposes */ +static int num_vterms = 0; + +static struct task_struct *hvc_task; + +/* + * This value is used to associate a tty->index value to a hvc_struct based + * upon order of exposure via hvc_probe(). + */ +static int hvc_count = -1; + +/* Picks up late kicks after list walk but before schedule() */ +static int hvc_kicked; + +/* Wake the sleeping khvcd */ +static void hvc_kick(void) +{ + hvc_kicked = 1; + wake_up_process(hvc_task); +} + +/* + * 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) +{ + hvc_kick(); + return IRQ_HANDLED; +} + +static void hvc_unthrottle(struct tty_struct *tty) +{ + hvc_kick(); +} + +/* + * 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; +} + +/* + * 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 + /* Handle the SysRq Hack */ + if (buf[i] == '\x0f') { /* ^O -- should support a sequence */ + 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) { + /*hp = list_entry(node, struct hvc_struct, * 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, +}; + +char hvc_driver_name[] = "hvc_console"; + +static struct vio_device_id hvc_driver_table[] __devinitdata= { + {"serial", "hvterm1"}, + { NULL, } +}; +MODULE_DEVICE_TABLE(vio, hvc_driver_table); + +/* 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, +}; + +static int __devinit hvc_probe( + struct vio_dev *dev, + const struct vio_device_id *id) +{ + struct hvc_struct *hp; + + /* probed with invalid parameters. */ + if (!dev || !id) + return -EPERM; + + hp = kmalloc(sizeof(*hp), GFP_KERNEL); + if (!hp) + return -ENOMEM; + + memset(hp, 0x00, sizeof(*hp)); + hp->vtermno = dev->unit_address; + hp->vdev = dev; + hp->vdev->dev.driver_data = hp; + hp->irq = dev->irq; + + kobject_init(&hp->kobj); + hp->kobj.ktype = &hvc_kobj_type; + + spin_lock_init(&hp->lock); + spin_lock(&hvc_structs_lock); + hp->index = ++hvc_count; + list_add_tail(&(hp->next), &hvc_structs); + spin_unlock(&hvc_structs_lock); + + return 0; +} + +static int __devexit hvc_remove(struct vio_dev *dev) +{ + struct hvc_struct *hp = dev->dev.driver_data; + 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; +} + +static struct vio_driver hvc_vio_driver = { + .name = hvc_driver_name, + .id_table = hvc_driver_table, + .probe = hvc_probe, + .remove = hvc_remove, +}; + +/* Driver initialization. Follow console initialization. This is where the TTY + * interfaces start to become available. */ +int __init hvc_init(void) +{ + int rc; + + /* We need more than num_vterms adapters due to hotplug additions. */ + hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS); + /* hvc_driver = alloc_tty_driver(num_vterms); */ + 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; + } + + /* Register as a vio device to receive callbacks */ + rc = vio_register_driver(&hvc_vio_driver); + + return rc; +} + +/* 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); + + vio_unregister_driver(&hvc_vio_driver); + tty_unregister_driver(hvc_driver); + /* return tty_struct instances allocated in hvc_init(). */ + put_tty_driver(hvc_driver); +} + +/* + * Console APIs, NOT TTY. These APIs are available immediately when + * hvc_console_setup() finds adapters. + */ + +/* + * 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 the appear after early console init. + */ +int hvc_instantiate(uint32_t vtermno, int index) +{ + if (index < 0 || index >= MAX_NR_HVC_CONSOLES) + return -1; + + if (vtermnos[index] != -1) + return -1; + + vtermnos[index] = vtermno; + return 0; +} + +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) +{ + *index = c->index; + return hvc_driver; +} + +static int __init hvc_console_setup(struct console *co, char *options) +{ + 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. */ +static int __init hvc_console_init(void) +{ + int i; + + for (i=0; i<MAX_NR_HVC_CONSOLES; i++) + vtermnos[i] = -1; + num_vterms = hvc_find_vtys(); + register_console(&hvc_con_driver); + return 0; +} +console_initcall(hvc_console_init); + +module_init(hvc_init); +module_exit(hvc_exit); |