diff options
Diffstat (limited to 'drivers/tty/tty_port.c')
| -rw-r--r-- | drivers/tty/tty_port.c | 223 |
1 files changed, 144 insertions, 79 deletions
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c index 2f1061a9d926..7709ce655f44 100644 --- a/drivers/tty/tty_port.c +++ b/drivers/tty/tty_port.c @@ -59,6 +59,15 @@ const struct tty_port_client_operations tty_port_default_client_ops = { }; EXPORT_SYMBOL_GPL(tty_port_default_client_ops); +/** + * tty_port_init -- initialize tty_port + * @port: tty_port to initialize + * + * Initializes the state of struct tty_port. When a port was initialized using + * this function, one has to destroy the port by tty_port_destroy(). Either + * indirectly by using &tty_port refcounting (tty_port_put()) or directly if + * refcounting is not used. + */ void tty_port_init(struct tty_port *port) { memset(port, 0, sizeof(*port)); @@ -82,9 +91,9 @@ EXPORT_SYMBOL(tty_port_init); * @index: index of the tty * * Provide the tty layer with a 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. + * 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) @@ -102,9 +111,9 @@ EXPORT_SYMBOL_GPL(tty_port_link_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. + * 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, @@ -123,9 +132,9 @@ EXPORT_SYMBOL_GPL(tty_port_register_device); * @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. + * 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, @@ -240,9 +249,9 @@ EXPORT_SYMBOL(tty_port_free_xmit_buf); * tty_port_destroy -- destroy inited port * @port: tty port to be destroyed * - * 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. + * 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) { @@ -267,6 +276,13 @@ static void tty_port_destructor(struct kref *kref) kfree(port); } +/** + * tty_port_put -- drop a reference to tty_port + * @port: port to drop a reference of (can be NULL) + * + * The final put will destroy and free up the @port using + * @port->ops->destruct() hook, or using kfree() if not provided. + */ void tty_port_put(struct tty_port *port) { if (port) @@ -275,11 +291,11 @@ void tty_port_put(struct tty_port *port) EXPORT_SYMBOL(tty_port_put); /** - * tty_port_tty_get - get a tty reference - * @port: tty port + * 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) + * 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) { @@ -294,12 +310,12 @@ struct tty_struct *tty_port_tty_get(struct tty_port *port) EXPORT_SYMBOL(tty_port_tty_get); /** - * tty_port_tty_set - set the tty of a port - * @port: tty port - * @tty: the tty + * 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 + * 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) { @@ -312,6 +328,16 @@ void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty) } EXPORT_SYMBOL(tty_port_tty_set); +/** + * tty_port_shutdown - internal helper to shutdown the device + * @port: tty port to be shut down + * @tty: the associated tty + * + * It is used by tty_port_hangup() and tty_port_close(). Its task is to + * shutdown the device if it was initialized (note consoles remain + * functioning). It lowers DTR/RTS (if @tty has HUPCL set) and invokes + * @port->ops->shutdown(). + */ static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty) { mutex_lock(&port->mutex); @@ -335,13 +361,13 @@ out: } /** - * tty_port_hangup - hangup helper - * @port: tty port + * tty_port_hangup - hangup helper + * @port: tty port * - * Perform port level tty hangup flag and count changes. Drop the tty - * reference. + * Perform port level tty hangup flag and count changes. Drop the tty + * reference. * - * Caller holds tty lock. + * Caller holds tty lock. */ void tty_port_hangup(struct tty_port *port) { @@ -365,9 +391,8 @@ 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? + * @check_clocal: hang only ttys with %CLOCAL unset? */ void tty_port_tty_hangup(struct tty_port *port, bool check_clocal) { @@ -381,7 +406,6 @@ 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) @@ -391,12 +415,12 @@ void tty_port_tty_wakeup(struct tty_port *port) EXPORT_SYMBOL_GPL(tty_port_tty_wakeup); /** - * tty_port_carrier_raised - carrier raised check - * @port: tty port + * 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. + * 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) { @@ -407,12 +431,12 @@ int tty_port_carrier_raised(struct tty_port *port) EXPORT_SYMBOL(tty_port_carrier_raised); /** - * tty_port_raise_dtr_rts - Raise DTR/RTS - * @port: tty port + * 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. + * 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) { @@ -422,12 +446,12 @@ void tty_port_raise_dtr_rts(struct tty_port *port) EXPORT_SYMBOL(tty_port_raise_dtr_rts); /** - * tty_port_lower_dtr_rts - Lower DTR/RTS - * @port: tty port + * 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. + * 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) { @@ -437,28 +461,29 @@ void tty_port_lower_dtr_rts(struct tty_port *port) 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 or NULL - * - * 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). + * 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 or %NULL + * + * 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 @port must implement the @port->ops->carrier_raised method if it + * can do carrier detect and the @port->ops->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. + * + * Note: May drop and reacquire tty lock when blocking, so @tty and @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) @@ -560,7 +585,21 @@ static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty) schedule_timeout_interruptible(timeout); } -/* Caller holds tty lock. */ +/** + * tty_port_close_start - helper for tty->ops->close, part 1/2 + * @port: tty_port of the device + * @tty: tty being closed + * @filp: passed file pointer + * + * Decrements and checks open count. Flushes the port if this is the last + * close. That means, dropping the data from the outpu buffer on the device and + * waiting for sending logic to finish. The rest of close handling is performed + * in tty_port_close_end(). + * + * Locking: Caller holds tty lock. + * + * Return: 1 if this is the last close, otherwise 0 + */ int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, struct file *filp) { @@ -606,7 +645,17 @@ int tty_port_close_start(struct tty_port *port, } EXPORT_SYMBOL(tty_port_close_start); -/* Caller holds tty lock */ +/** + * tty_port_close_end - helper for tty->ops->close, part 2/2 + * @port: tty_port of the device + * @tty: tty being closed + * + * This is a continuation of the first part: tty_port_close_start(). This + * should be called after turning off the device. It flushes the data from the + * line discipline and delays the close by @port->close_delay. + * + * Locking: Caller holds tty lock. + */ void tty_port_close_end(struct tty_port *port, struct tty_struct *tty) { unsigned long flags; @@ -628,10 +677,18 @@ void tty_port_close_end(struct tty_port *port, struct tty_struct *tty) } EXPORT_SYMBOL(tty_port_close_end); -/* - * tty_port_close +/** + * tty_port_close - generic tty->ops->close handler + * @port: tty_port of the device + * @tty: tty being closed + * @filp: passed file pointer + * + * It is a generic helper to be used in driver's @tty->ops->close. It wraps a + * sequence of tty_port_close_start(), tty_port_shutdown(), and + * tty_port_close_end(). The latter two are called only if this is the last + * close. See the respective functions for the details. * - * Caller holds tty lock + * Locking: Caller holds tty lock */ void tty_port_close(struct tty_port *port, struct tty_struct *tty, struct file *filp) @@ -652,9 +709,9 @@ EXPORT_SYMBOL(tty_port_close); * @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. + * 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) @@ -664,13 +721,21 @@ int tty_port_install(struct tty_port *port, struct tty_driver *driver, } EXPORT_SYMBOL_GPL(tty_port_install); -/* - * tty_port_open +/** + * tty_port_open - generic tty->ops->open handler + * @port: tty_port of the device + * @tty: tty to be opened + * @filp: passed file pointer * - * Caller holds tty lock. + * It is a generic helper to be used in driver's @tty->ops->open. It activates + * the devices using @port->ops->activate if not active already. And waits for + * the device to be ready using tty_port_block_til_ready() (e.g. raises + * DTR/CTS and waits for carrier). + * + * Locking: 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) + * Note: may drop and reacquire tty lock (in tty_port_block_til_ready()) so + * @tty and @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) |