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Diffstat (limited to 'include/linux/tty_port.h')
| -rw-r--r-- | include/linux/tty_port.h | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/include/linux/tty_port.h b/include/linux/tty_port.h new file mode 100644 index 000000000..6b367eb17 --- /dev/null +++ b/include/linux/tty_port.h @@ -0,0 +1,257 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_TTY_PORT_H +#define _LINUX_TTY_PORT_H + +#include <linux/kfifo.h> +#include <linux/kref.h> +#include <linux/mutex.h> +#include <linux/tty_buffer.h> +#include <linux/wait.h> + +struct attribute_group; +struct tty_driver; +struct tty_port; +struct tty_struct; + +/** + * struct tty_port_operations -- operations on tty_port + * @carrier_raised: return true if the carrier is raised on @port + * @dtr_rts: raise the DTR line if @active is true, otherwise lower DTR + * @shutdown: called when the last close completes or a hangup finishes IFF the + * port was initialized. Do not use to free resources. Turn off the device + * only. Called under the port mutex to serialize against @activate and + * @shutdown. + * @activate: called under the port mutex from tty_port_open(), serialized using + * the port mutex. Supposed to turn on the device. + * + * FIXME: long term getting the tty argument *out* of this would be good + * for consoles. + * + * @destruct: called on the final put of a port. Free resources, possibly incl. + * the port itself. + */ +struct tty_port_operations { + bool (*carrier_raised)(struct tty_port *port); + void (*dtr_rts)(struct tty_port *port, bool active); + void (*shutdown)(struct tty_port *port); + int (*activate)(struct tty_port *port, struct tty_struct *tty); + void (*destruct)(struct tty_port *port); +}; + +struct tty_port_client_operations { + size_t (*receive_buf)(struct tty_port *port, const u8 *cp, const u8 *fp, + size_t count); + void (*lookahead_buf)(struct tty_port *port, const u8 *cp, + const u8 *fp, size_t count); + void (*write_wakeup)(struct tty_port *port); +}; + +extern const struct tty_port_client_operations tty_port_default_client_ops; + +/** + * struct tty_port -- port level information + * + * @buf: buffer for this port, locked internally + * @tty: back pointer to &struct tty_struct, valid only if the tty is open. Use + * tty_port_tty_get() to obtain it (and tty_kref_put() to release). + * @itty: internal back pointer to &struct tty_struct. Avoid this. It should be + * eliminated in the long term. + * @ops: tty port operations (like activate, shutdown), see &struct + * tty_port_operations + * @client_ops: tty port client operations (like receive_buf, write_wakeup). + * By default, tty_port_default_client_ops is used. + * @lock: lock protecting @tty + * @blocked_open: # of procs waiting for open in tty_port_block_til_ready() + * @count: usage count + * @open_wait: open waiters queue (waiting e.g. for a carrier) + * @delta_msr_wait: modem status change queue (waiting for MSR changes) + * @flags: user TTY flags (%ASYNC_) + * @iflags: internal flags (%TTY_PORT_) + * @console: when set, the port is a console + * @mutex: locking, for open, shutdown and other port operations + * @buf_mutex: @xmit_buf alloc lock + * @xmit_buf: optional xmit buffer used by some drivers + * @xmit_fifo: optional xmit buffer used by some drivers + * @close_delay: delay in jiffies to wait when closing the port + * @closing_wait: delay in jiffies for output to be sent before closing + * @drain_delay: set to zero if no pure time based drain is needed else set to + * size of fifo + * @kref: references counter. Reaching zero calls @ops->destruct() if non-%NULL + * or frees the port otherwise. + * @client_data: pointer to private data, for @client_ops + * + * Each device keeps its own port level information. &struct tty_port was + * introduced as a common structure for such information. As every TTY device + * shall have a backing tty_port structure, every driver can use these members. + * + * The tty port has a different lifetime to the tty so must be kept apart. + * In addition be careful as tty -> port mappings are valid for the life + * of the tty object but in many cases port -> tty mappings are valid only + * until a hangup so don't use the wrong path. + * + * Tty port shall be initialized by tty_port_init() and shut down either by + * tty_port_destroy() (refcounting not used), or tty_port_put() (refcounting). + * + * There is a lot of helpers around &struct tty_port too. To name the most + * significant ones: tty_port_open(), tty_port_close() (or + * tty_port_close_start() and tty_port_close_end() separately if need be), and + * tty_port_hangup(). These call @ops->activate() and @ops->shutdown() as + * needed. + */ +struct tty_port { + struct tty_bufhead buf; + struct tty_struct *tty; + struct tty_struct *itty; + const struct tty_port_operations *ops; + const struct tty_port_client_operations *client_ops; + spinlock_t lock; + int blocked_open; + int count; + wait_queue_head_t open_wait; + wait_queue_head_t delta_msr_wait; + unsigned long flags; + unsigned long iflags; + unsigned char console:1; + struct mutex mutex; + struct mutex buf_mutex; + unsigned char *xmit_buf; + DECLARE_KFIFO_PTR(xmit_fifo, unsigned char); + unsigned int close_delay; + unsigned int closing_wait; + int drain_delay; + struct kref kref; + void *client_data; +}; + +/* tty_port::iflags bits -- use atomic bit ops */ +#define TTY_PORT_INITIALIZED 0 /* device is initialized */ +#define TTY_PORT_SUSPENDED 1 /* device is suspended */ +#define TTY_PORT_ACTIVE 2 /* device is open */ + +/* + * uart drivers: use the uart_port::status field and the UPSTAT_* defines + * for s/w-based flow control steering and carrier detection status + */ +#define TTY_PORT_CTS_FLOW 3 /* h/w flow control enabled */ +#define TTY_PORT_CHECK_CD 4 /* carrier detect enabled */ +#define TTY_PORT_KOPENED 5 /* device exclusively opened by + kernel */ + +void tty_port_init(struct tty_port *port); +void tty_port_link_device(struct tty_port *port, struct tty_driver *driver, + unsigned index); +struct device *tty_port_register_device(struct tty_port *port, + struct tty_driver *driver, unsigned index, + struct device *device); +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); +struct device *tty_port_register_device_serdev(struct tty_port *port, + struct tty_driver *driver, unsigned index, + struct device *device); +struct device *tty_port_register_device_attr_serdev(struct tty_port *port, + struct tty_driver *driver, unsigned index, + struct device *device, void *drvdata, + const struct attribute_group **attr_grp); +void tty_port_unregister_device(struct tty_port *port, + struct tty_driver *driver, unsigned index); +int tty_port_alloc_xmit_buf(struct tty_port *port); +void tty_port_free_xmit_buf(struct tty_port *port); +void tty_port_destroy(struct tty_port *port); +void tty_port_put(struct tty_port *port); + +static inline struct tty_port *tty_port_get(struct tty_port *port) +{ + if (port && kref_get_unless_zero(&port->kref)) + return port; + return NULL; +} + +/* If the cts flow control is enabled, return true. */ +static inline bool tty_port_cts_enabled(const struct tty_port *port) +{ + return test_bit(TTY_PORT_CTS_FLOW, &port->iflags); +} + +static inline void tty_port_set_cts_flow(struct tty_port *port, bool val) +{ + assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val); +} + +static inline bool tty_port_active(const struct tty_port *port) +{ + return test_bit(TTY_PORT_ACTIVE, &port->iflags); +} + +static inline void tty_port_set_active(struct tty_port *port, bool val) +{ + assign_bit(TTY_PORT_ACTIVE, &port->iflags, val); +} + +static inline bool tty_port_check_carrier(const struct tty_port *port) +{ + return test_bit(TTY_PORT_CHECK_CD, &port->iflags); +} + +static inline void tty_port_set_check_carrier(struct tty_port *port, bool val) +{ + assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val); +} + +static inline bool tty_port_suspended(const struct tty_port *port) +{ + return test_bit(TTY_PORT_SUSPENDED, &port->iflags); +} + +static inline void tty_port_set_suspended(struct tty_port *port, bool val) +{ + assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val); +} + +static inline bool tty_port_initialized(const struct tty_port *port) +{ + return test_bit(TTY_PORT_INITIALIZED, &port->iflags); +} + +static inline void tty_port_set_initialized(struct tty_port *port, bool val) +{ + assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val); +} + +static inline bool tty_port_kopened(const struct tty_port *port) +{ + return test_bit(TTY_PORT_KOPENED, &port->iflags); +} + +static inline void tty_port_set_kopened(struct tty_port *port, bool val) +{ + assign_bit(TTY_PORT_KOPENED, &port->iflags, val); +} + +struct tty_struct *tty_port_tty_get(struct tty_port *port); +void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty); +bool tty_port_carrier_raised(struct tty_port *port); +void tty_port_raise_dtr_rts(struct tty_port *port); +void tty_port_lower_dtr_rts(struct tty_port *port); +void tty_port_hangup(struct tty_port *port); +void tty_port_tty_hangup(struct tty_port *port, bool check_clocal); +void tty_port_tty_wakeup(struct tty_port *port); +int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty, + struct file *filp); +int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, + struct file *filp); +void tty_port_close_end(struct tty_port *port, struct tty_struct *tty); +void tty_port_close(struct tty_port *port, struct tty_struct *tty, + struct file *filp); +int tty_port_install(struct tty_port *port, struct tty_driver *driver, + struct tty_struct *tty); +int tty_port_open(struct tty_port *port, struct tty_struct *tty, + struct file *filp); + +static inline int tty_port_users(struct tty_port *port) +{ + return port->count + port->blocked_open; +} + +#endif |