diff options
Diffstat (limited to 'drivers/tty/tty_port.c')
| -rw-r--r-- | drivers/tty/tty_port.c | 620 |
1 files changed, 620 insertions, 0 deletions
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c new file mode 100644 index 000000000..40b31835f --- /dev/null +++ b/drivers/tty/tty_port.c @@ -0,0 +1,620 @@ +/* + * Tty port functions + */ + +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/tty.h> +#include <linux/tty_driver.h> +#include <linux/tty_flip.h> +#include <linux/serial.h> +#include <linux/timer.h> +#include <linux/string.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/wait.h> +#include <linux/bitops.h> +#include <linux/delay.h> +#include <linux/module.h> + +void tty_port_init(struct tty_port *port) +{ + memset(port, 0, sizeof(*port)); + tty_buffer_init(port); + init_waitqueue_head(&port->open_wait); + init_waitqueue_head(&port->close_wait); + init_waitqueue_head(&port->delta_msr_wait); + mutex_init(&port->mutex); + mutex_init(&port->buf_mutex); + spin_lock_init(&port->lock); + port->close_delay = (50 * HZ) / 100; + port->closing_wait = (3000 * HZ) / 100; + kref_init(&port->kref); +} +EXPORT_SYMBOL(tty_port_init); + +/** + * tty_port_link_device - link tty and tty_port + * @port: tty_port of the device + * @driver: tty_driver for this device + * @index: index of the tty + * + * Provide the tty layer wit ha link from a tty (specified by @index) to a + * tty_port (@port). Use this only if neither tty_port_register_device nor + * tty_port_install is used in the driver. If used, this has to be called before + * tty_register_driver. + */ +void tty_port_link_device(struct tty_port *port, + struct tty_driver *driver, unsigned index) +{ + if (WARN_ON(index >= driver->num)) + return; + driver->ports[index] = port; +} +EXPORT_SYMBOL_GPL(tty_port_link_device); + +/** + * tty_port_register_device - register tty device + * @port: tty_port of the device + * @driver: tty_driver for this device + * @index: index of the tty + * @device: parent if exists, otherwise NULL + * + * It is the same as tty_register_device except the provided @port is linked to + * a concrete tty specified by @index. Use this or tty_port_install (or both). + * Call tty_port_link_device as a last resort. + */ +struct device *tty_port_register_device(struct tty_port *port, + struct tty_driver *driver, unsigned index, + struct device *device) +{ + tty_port_link_device(port, driver, index); + return tty_register_device(driver, index, device); +} +EXPORT_SYMBOL_GPL(tty_port_register_device); + +/** + * tty_port_register_device_attr - register tty device + * @port: tty_port of the device + * @driver: tty_driver for this device + * @index: index of the tty + * @device: parent if exists, otherwise NULL + * @drvdata: Driver data to be set to device. + * @attr_grp: Attribute group to be set on device. + * + * It is the same as tty_register_device_attr except the provided @port is + * linked to a concrete tty specified by @index. Use this or tty_port_install + * (or both). Call tty_port_link_device as a last resort. + */ +struct device *tty_port_register_device_attr(struct tty_port *port, + struct tty_driver *driver, unsigned index, + struct device *device, void *drvdata, + const struct attribute_group **attr_grp) +{ + tty_port_link_device(port, driver, index); + return tty_register_device_attr(driver, index, device, drvdata, + attr_grp); +} +EXPORT_SYMBOL_GPL(tty_port_register_device_attr); + +int tty_port_alloc_xmit_buf(struct tty_port *port) +{ + /* We may sleep in get_zeroed_page() */ + mutex_lock(&port->buf_mutex); + if (port->xmit_buf == NULL) + port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL); + mutex_unlock(&port->buf_mutex); + if (port->xmit_buf == NULL) + return -ENOMEM; + return 0; +} +EXPORT_SYMBOL(tty_port_alloc_xmit_buf); + +void tty_port_free_xmit_buf(struct tty_port *port) +{ + mutex_lock(&port->buf_mutex); + if (port->xmit_buf != NULL) { + free_page((unsigned long)port->xmit_buf); + port->xmit_buf = NULL; + } + mutex_unlock(&port->buf_mutex); +} +EXPORT_SYMBOL(tty_port_free_xmit_buf); + +/** + * tty_port_destroy -- destroy inited port + * @port: tty port to be doestroyed + * + * When a port was initialized using tty_port_init, one has to destroy the + * port by this function. Either indirectly by using tty_port refcounting + * (tty_port_put) or directly if refcounting is not used. + */ +void tty_port_destroy(struct tty_port *port) +{ + cancel_work_sync(&port->buf.work); + tty_buffer_free_all(port); +} +EXPORT_SYMBOL(tty_port_destroy); + +static void tty_port_destructor(struct kref *kref) +{ + struct tty_port *port = container_of(kref, struct tty_port, kref); + + /* check if last port ref was dropped before tty release */ + if (WARN_ON(port->itty)) + return; + if (port->xmit_buf) + free_page((unsigned long)port->xmit_buf); + tty_port_destroy(port); + if (port->ops && port->ops->destruct) + port->ops->destruct(port); + else + kfree(port); +} + +void tty_port_put(struct tty_port *port) +{ + if (port) + kref_put(&port->kref, tty_port_destructor); +} +EXPORT_SYMBOL(tty_port_put); + +/** + * tty_port_tty_get - get a tty reference + * @port: tty port + * + * Return a refcount protected tty instance or NULL if the port is not + * associated with a tty (eg due to close or hangup) + */ + +struct tty_struct *tty_port_tty_get(struct tty_port *port) +{ + unsigned long flags; + struct tty_struct *tty; + + spin_lock_irqsave(&port->lock, flags); + tty = tty_kref_get(port->tty); + spin_unlock_irqrestore(&port->lock, flags); + return tty; +} +EXPORT_SYMBOL(tty_port_tty_get); + +/** + * tty_port_tty_set - set the tty of a port + * @port: tty port + * @tty: the tty + * + * Associate the port and tty pair. Manages any internal refcounts. + * Pass NULL to deassociate a port + */ + +void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty) +{ + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + tty_kref_put(port->tty); + port->tty = tty_kref_get(tty); + spin_unlock_irqrestore(&port->lock, flags); +} +EXPORT_SYMBOL(tty_port_tty_set); + +static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty) +{ + mutex_lock(&port->mutex); + if (port->console) + goto out; + + if (test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags)) { + /* + * Drop DTR/RTS if HUPCL is set. This causes any attached + * modem to hang up the line. + */ + if (tty && C_HUPCL(tty)) + tty_port_lower_dtr_rts(port); + + if (port->ops->shutdown) + port->ops->shutdown(port); + } +out: + mutex_unlock(&port->mutex); +} + +/** + * tty_port_hangup - hangup helper + * @port: tty port + * + * Perform port level tty hangup flag and count changes. Drop the tty + * reference. + * + * Caller holds tty lock. + */ + +void tty_port_hangup(struct tty_port *port) +{ + struct tty_struct *tty; + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + port->count = 0; + port->flags &= ~ASYNC_NORMAL_ACTIVE; + tty = port->tty; + if (tty) + set_bit(TTY_IO_ERROR, &tty->flags); + port->tty = NULL; + spin_unlock_irqrestore(&port->lock, flags); + tty_port_shutdown(port, tty); + tty_kref_put(tty); + wake_up_interruptible(&port->open_wait); + wake_up_interruptible(&port->delta_msr_wait); +} +EXPORT_SYMBOL(tty_port_hangup); + +/** + * tty_port_tty_hangup - helper to hang up a tty + * + * @port: tty port + * @check_clocal: hang only ttys with CLOCAL unset? + */ +void tty_port_tty_hangup(struct tty_port *port, bool check_clocal) +{ + struct tty_struct *tty = tty_port_tty_get(port); + + if (tty && (!check_clocal || !C_CLOCAL(tty))) + tty_hangup(tty); + tty_kref_put(tty); +} +EXPORT_SYMBOL_GPL(tty_port_tty_hangup); + +/** + * tty_port_tty_wakeup - helper to wake up a tty + * + * @port: tty port + */ +void tty_port_tty_wakeup(struct tty_port *port) +{ + struct tty_struct *tty = tty_port_tty_get(port); + + if (tty) { + tty_wakeup(tty); + tty_kref_put(tty); + } +} +EXPORT_SYMBOL_GPL(tty_port_tty_wakeup); + +/** + * tty_port_carrier_raised - carrier raised check + * @port: tty port + * + * Wrapper for the carrier detect logic. For the moment this is used + * to hide some internal details. This will eventually become entirely + * internal to the tty port. + */ + +int tty_port_carrier_raised(struct tty_port *port) +{ + if (port->ops->carrier_raised == NULL) + return 1; + return port->ops->carrier_raised(port); +} +EXPORT_SYMBOL(tty_port_carrier_raised); + +/** + * tty_port_raise_dtr_rts - Raise DTR/RTS + * @port: tty port + * + * Wrapper for the DTR/RTS raise logic. For the moment this is used + * to hide some internal details. This will eventually become entirely + * internal to the tty port. + */ + +void tty_port_raise_dtr_rts(struct tty_port *port) +{ + if (port->ops->dtr_rts) + port->ops->dtr_rts(port, 1); +} +EXPORT_SYMBOL(tty_port_raise_dtr_rts); + +/** + * tty_port_lower_dtr_rts - Lower DTR/RTS + * @port: tty port + * + * Wrapper for the DTR/RTS raise logic. For the moment this is used + * to hide some internal details. This will eventually become entirely + * internal to the tty port. + */ + +void tty_port_lower_dtr_rts(struct tty_port *port) +{ + if (port->ops->dtr_rts) + port->ops->dtr_rts(port, 0); +} +EXPORT_SYMBOL(tty_port_lower_dtr_rts); + +/** + * tty_port_block_til_ready - Waiting logic for tty open + * @port: the tty port being opened + * @tty: the tty device being bound + * @filp: the file pointer of the opener + * + * Implement the core POSIX/SuS tty behaviour when opening a tty device. + * Handles: + * - hangup (both before and during) + * - non blocking open + * - rts/dtr/dcd + * - signals + * - port flags and counts + * + * The passed tty_port must implement the carrier_raised method if it can + * do carrier detect and the dtr_rts method if it supports software + * management of these lines. Note that the dtr/rts raise is done each + * iteration as a hangup may have previously dropped them while we wait. + * + * Caller holds tty lock. + * + * NB: May drop and reacquire tty lock when blocking, so tty and tty_port + * may have changed state (eg., may have been hung up). + */ + +int tty_port_block_til_ready(struct tty_port *port, + struct tty_struct *tty, struct file *filp) +{ + int do_clocal = 0, retval; + unsigned long flags; + DEFINE_WAIT(wait); + + /* block if port is in the process of being closed */ + if (port->flags & ASYNC_CLOSING) { + wait_event_interruptible_tty(tty, port->close_wait, + !(port->flags & ASYNC_CLOSING)); + if (port->flags & ASYNC_HUP_NOTIFY) + return -EAGAIN; + else + return -ERESTARTSYS; + } + + /* if non-blocking mode is set we can pass directly to open unless + the port has just hung up or is in another error state */ + if (tty->flags & (1 << TTY_IO_ERROR)) { + port->flags |= ASYNC_NORMAL_ACTIVE; + return 0; + } + if (filp->f_flags & O_NONBLOCK) { + /* Indicate we are open */ + if (tty->termios.c_cflag & CBAUD) + tty_port_raise_dtr_rts(port); + port->flags |= ASYNC_NORMAL_ACTIVE; + return 0; + } + + if (C_CLOCAL(tty)) + do_clocal = 1; + + /* Block waiting until we can proceed. We may need to wait for the + carrier, but we must also wait for any close that is in progress + before the next open may complete */ + + retval = 0; + + /* The port lock protects the port counts */ + spin_lock_irqsave(&port->lock, flags); + port->count--; + port->blocked_open++; + spin_unlock_irqrestore(&port->lock, flags); + + while (1) { + /* Indicate we are open */ + if (C_BAUD(tty) && test_bit(ASYNCB_INITIALIZED, &port->flags)) + tty_port_raise_dtr_rts(port); + + prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE); + /* Check for a hangup or uninitialised port. + Return accordingly */ + if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) { + if (port->flags & ASYNC_HUP_NOTIFY) + retval = -EAGAIN; + else + retval = -ERESTARTSYS; + break; + } + /* + * Probe the carrier. For devices with no carrier detect + * tty_port_carrier_raised will always return true. + * Never ask drivers if CLOCAL is set, this causes troubles + * on some hardware. + */ + if (!(port->flags & ASYNC_CLOSING) && + (do_clocal || tty_port_carrier_raised(port))) + break; + if (signal_pending(current)) { + retval = -ERESTARTSYS; + break; + } + tty_unlock(tty); + schedule(); + tty_lock(tty); + } + finish_wait(&port->open_wait, &wait); + + /* Update counts. A parallel hangup will have set count to zero and + we must not mess that up further */ + spin_lock_irqsave(&port->lock, flags); + if (!tty_hung_up_p(filp)) + port->count++; + port->blocked_open--; + if (retval == 0) + port->flags |= ASYNC_NORMAL_ACTIVE; + spin_unlock_irqrestore(&port->lock, flags); + return retval; +} +EXPORT_SYMBOL(tty_port_block_til_ready); + +static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty) +{ + unsigned int bps = tty_get_baud_rate(tty); + long timeout; + + if (bps > 1200) { + timeout = (HZ * 10 * port->drain_delay) / bps; + timeout = max_t(long, timeout, HZ / 10); + } else { + timeout = 2 * HZ; + } + schedule_timeout_interruptible(timeout); +} + +/* Caller holds tty lock. + * NB: may drop and reacquire tty lock (in tty_wait_until_sent_from_close()) + * so tty and tty port may have changed state (but not hung up or reopened). + */ +int tty_port_close_start(struct tty_port *port, + struct tty_struct *tty, struct file *filp) +{ + unsigned long flags; + + if (tty_hung_up_p(filp)) + return 0; + + spin_lock_irqsave(&port->lock, flags); + if (tty->count == 1 && port->count != 1) { + printk(KERN_WARNING + "tty_port_close_start: tty->count = 1 port count = %d.\n", + port->count); + port->count = 1; + } + if (--port->count < 0) { + printk(KERN_WARNING "tty_port_close_start: count = %d\n", + port->count); + port->count = 0; + } + + if (port->count) { + spin_unlock_irqrestore(&port->lock, flags); + return 0; + } + set_bit(ASYNCB_CLOSING, &port->flags); + spin_unlock_irqrestore(&port->lock, flags); + + tty->closing = 1; + + if (test_bit(ASYNCB_INITIALIZED, &port->flags)) { + /* Don't block on a stalled port, just pull the chain */ + if (tty->flow_stopped) + tty_driver_flush_buffer(tty); + if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE) + tty_wait_until_sent_from_close(tty, port->closing_wait); + if (port->drain_delay) + tty_port_drain_delay(port, tty); + } + /* Flush the ldisc buffering */ + tty_ldisc_flush(tty); + + /* Report to caller this is the last port reference */ + return 1; +} +EXPORT_SYMBOL(tty_port_close_start); + +/* Caller holds tty lock */ +void tty_port_close_end(struct tty_port *port, struct tty_struct *tty) +{ + unsigned long flags; + + tty_ldisc_flush(tty); + tty->closing = 0; + + spin_lock_irqsave(&port->lock, flags); + + if (port->blocked_open) { + spin_unlock_irqrestore(&port->lock, flags); + if (port->close_delay) { + msleep_interruptible( + jiffies_to_msecs(port->close_delay)); + } + spin_lock_irqsave(&port->lock, flags); + wake_up_interruptible(&port->open_wait); + } + port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING); + wake_up_interruptible(&port->close_wait); + spin_unlock_irqrestore(&port->lock, flags); +} +EXPORT_SYMBOL(tty_port_close_end); + +/** + * tty_port_close + * + * Caller holds tty lock + * + * NB: may drop and reacquire tty lock (in tty_port_close_start()-> + * tty_wait_until_sent_from_close()) so tty and tty_port may have changed + * state (but not hung up or reopened). + */ +void tty_port_close(struct tty_port *port, struct tty_struct *tty, + struct file *filp) +{ + if (tty_port_close_start(port, tty, filp) == 0) + return; + tty_port_shutdown(port, tty); + set_bit(TTY_IO_ERROR, &tty->flags); + tty_port_close_end(port, tty); + tty_port_tty_set(port, NULL); +} +EXPORT_SYMBOL(tty_port_close); + +/** + * tty_port_install - generic tty->ops->install handler + * @port: tty_port of the device + * @driver: tty_driver for this device + * @tty: tty to be installed + * + * It is the same as tty_standard_install except the provided @port is linked + * to a concrete tty specified by @tty. Use this or tty_port_register_device + * (or both). Call tty_port_link_device as a last resort. + */ +int tty_port_install(struct tty_port *port, struct tty_driver *driver, + struct tty_struct *tty) +{ + tty->port = port; + return tty_standard_install(driver, tty); +} +EXPORT_SYMBOL_GPL(tty_port_install); + +/** + * tty_port_open + * + * Caller holds tty lock. + * + * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so + * tty and tty_port may have changed state (eg., may be hung up now) + */ +int tty_port_open(struct tty_port *port, struct tty_struct *tty, + struct file *filp) +{ + spin_lock_irq(&port->lock); + ++port->count; + spin_unlock_irq(&port->lock); + tty_port_tty_set(port, tty); + + /* + * Do the device-specific open only if the hardware isn't + * already initialized. Serialize open and shutdown using the + * port mutex. + */ + + mutex_lock(&port->mutex); + + if (!test_bit(ASYNCB_INITIALIZED, &port->flags)) { + clear_bit(TTY_IO_ERROR, &tty->flags); + if (port->ops->activate) { + int retval = port->ops->activate(port, tty); + if (retval) { + mutex_unlock(&port->mutex); + return retval; + } + } + set_bit(ASYNCB_INITIALIZED, &port->flags); + } + mutex_unlock(&port->mutex); + return tty_port_block_til_ready(port, tty, filp); +} + +EXPORT_SYMBOL(tty_port_open); |