Merge tag 'tty-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty / serial updates from Greg KH:
 "Here is the big set of tty/serial driver changes for 6.10-rc1.
  Included in here are:

   - Usual good set of api cleanups and evolution by Jiri Slaby to make
     the serial interfaces move out of the 1990's by using kfifos
     instead of hand-rolling their own logic.

   - 8250_exar driver updates

   - max3100 driver updates

   - sc16is7xx driver updates

   - exar driver updates

   - sh-sci driver updates

   - tty ldisc api addition to help refuse bindings

   - other smaller serial driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (113 commits)
  serial: Clear UPF_DEAD before calling tty_port_register_device_attr_serdev()
  serial: imx: Raise TX trigger level to 8
  serial: 8250_pnp: Simplify "line" related code
  serial: sh-sci: simplify locking when re-issuing RXDMA fails
  serial: sh-sci: let timeout timer only run when DMA is scheduled
  serial: sh-sci: describe locking requirements for invalidating RXDMA
  serial: sh-sci: protect invalidating RXDMA on shutdown
  tty: add the option to have a tty reject a new ldisc
  serial: core: Call device_set_awake_path() for console port
  dt-bindings: serial: brcm,bcm2835-aux-uart: convert to dtschema
  tty: serial: uartps: Add support for uartps controller reset
  arm64: zynqmp: Add resets property for UART nodes
  dt-bindings: serial: cdns,uart: Add optional reset property
  serial: 8250_pnp: Switch to DEFINE_SIMPLE_DEV_PM_OPS()
  serial: 8250_exar: Keep the includes sorted
  serial: 8250_exar: Make type of bit the same in exar_ee_*_bit()
  serial: 8250_exar: Use BIT() in exar_ee_read()
  serial: 8250_exar: Switch to use dev_err_probe()
  serial: 8250_exar: Return directly from switch-cases
  serial: 8250_exar: Decrease indentation level
  ...

6 files changed, 158 insertions, 101 deletions

diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
index 6b28d642f332..564868bdce89 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -37,6 +37,7 @@
  */
 
 #include <linux/array_size.h>
+#include <linux/dma-mapping.h>
 #include <linux/spinlock.h>
 #include <linux/stddef.h>
 #include <linux/types.h>
@@ -309,19 +310,25 @@ __kfifo_uint_must_check_helper( \
 )
 
 /**
- * kfifo_skip - skip output data
+ * kfifo_skip_count - skip output data
  * @fifo: address of the fifo to be used
+ * @count: count of data to skip
  */
-#define	kfifo_skip(fifo) \
-(void)({ \
+#define	kfifo_skip_count(fifo, count) do { \
 	typeof((fifo) + 1) __tmp = (fifo); \
 	const size_t __recsize = sizeof(*__tmp->rectype); \
 	struct __kfifo *__kfifo = &__tmp->kfifo; \
 	if (__recsize) \
 		__kfifo_skip_r(__kfifo, __recsize); \
 	else \
-		__kfifo->out++; \
-})
+		__kfifo->out += (count); \
+} while(0)
+
+/**
+ * kfifo_skip - skip output data
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_skip(fifo)	kfifo_skip_count(fifo, 1)
 
 /**
  * kfifo_peek_len - gets the size of the next fifo record
@@ -583,7 +590,7 @@ __kfifo_uint_must_check_helper( \
  * @buf: pointer to the storage buffer
  * @n: max. number of elements to get
  *
- * This macro get some data from the fifo and return the numbers of elements
+ * This macro gets some data from the fifo and returns the numbers of elements
  * copied.
  *
  * Note that with only one concurrent reader and one concurrent
@@ -610,7 +617,7 @@ __kfifo_uint_must_check_helper( \
  * @n: max. number of elements to get
  * @lock: pointer to the spinlock to use for locking
  *
- * This macro get the data from the fifo and return the numbers of elements
+ * This macro gets the data from the fifo and returns the numbers of elements
  * copied.
  */
 #define	kfifo_out_spinlocked(fifo, buf, n, lock) \
@@ -708,11 +715,12 @@ __kfifo_int_must_check_helper( \
 )
 
 /**
- * kfifo_dma_in_prepare - setup a scatterlist for DMA input
+ * kfifo_dma_in_prepare_mapped - setup a scatterlist for DMA input
  * @fifo: address of the fifo to be used
  * @sgl: pointer to the scatterlist array
  * @nents: number of entries in the scatterlist array
  * @len: number of elements to transfer
+ * @dma: mapped dma address to fill into @sgl
  *
  * This macro fills a scatterlist for DMA input.
  * It returns the number entries in the scatterlist array.
@@ -720,7 +728,7 @@ __kfifo_int_must_check_helper( \
  * Note that with only one concurrent reader and one concurrent
  * writer, you don't need extra locking to use these macros.
  */
-#define	kfifo_dma_in_prepare(fifo, sgl, nents, len) \
+#define	kfifo_dma_in_prepare_mapped(fifo, sgl, nents, len, dma) \
 ({ \
 	typeof((fifo) + 1) __tmp = (fifo); \
 	struct scatterlist *__sgl = (sgl); \
@@ -729,16 +737,20 @@ __kfifo_int_must_check_helper( \
 	const size_t __recsize = sizeof(*__tmp->rectype); \
 	struct __kfifo *__kfifo = &__tmp->kfifo; \
 	(__recsize) ? \
-	__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
-	__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len); \
+	__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize, \
+				 dma) : \
+	__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len, dma); \
 })
 
+#define kfifo_dma_in_prepare(fifo, sgl, nents, len) \
+	kfifo_dma_in_prepare_mapped(fifo, sgl, nents, len, DMA_MAPPING_ERROR)
+
 /**
  * kfifo_dma_in_finish - finish a DMA IN operation
  * @fifo: address of the fifo to be used
  * @len: number of bytes to received
  *
- * This macro finish a DMA IN operation. The in counter will be updated by
+ * This macro finishes a DMA IN operation. The in counter will be updated by
  * the len parameter. No error checking will be done.
  *
  * Note that with only one concurrent reader and one concurrent
@@ -757,11 +769,12 @@ __kfifo_int_must_check_helper( \
 })
 
 /**
- * kfifo_dma_out_prepare - setup a scatterlist for DMA output
+ * kfifo_dma_out_prepare_mapped - setup a scatterlist for DMA output
  * @fifo: address of the fifo to be used
  * @sgl: pointer to the scatterlist array
  * @nents: number of entries in the scatterlist array
  * @len: number of elements to transfer
+ * @dma: mapped dma address to fill into @sgl
  *
  * This macro fills a scatterlist for DMA output which at most @len bytes
  * to transfer.
@@ -771,7 +784,7 @@ __kfifo_int_must_check_helper( \
  * Note that with only one concurrent reader and one concurrent
  * writer, you don't need extra locking to use these macros.
  */
-#define	kfifo_dma_out_prepare(fifo, sgl, nents, len) \
+#define	kfifo_dma_out_prepare_mapped(fifo, sgl, nents, len, dma) \
 ({ \
 	typeof((fifo) + 1) __tmp = (fifo);  \
 	struct scatterlist *__sgl = (sgl); \
@@ -780,32 +793,29 @@ __kfifo_int_must_check_helper( \
 	const size_t __recsize = sizeof(*__tmp->rectype); \
 	struct __kfifo *__kfifo = &__tmp->kfifo; \
 	(__recsize) ? \
-	__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
-	__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len); \
+	__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize, \
+				  dma) : \
+	__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len, dma); \
 })
 
+#define	kfifo_dma_out_prepare(fifo, sgl, nents, len) \
+	kfifo_dma_out_prepare_mapped(fifo, sgl, nents, len, DMA_MAPPING_ERROR)
+
 /**
  * kfifo_dma_out_finish - finish a DMA OUT operation
  * @fifo: address of the fifo to be used
  * @len: number of bytes transferred
  *
- * This macro finish a DMA OUT operation. The out counter will be updated by
+ * This macro finishes a DMA OUT operation. The out counter will be updated by
  * the len parameter. No error checking will be done.
  *
  * Note that with only one concurrent reader and one concurrent
  * writer, you don't need extra locking to use these macros.
  */
-#define kfifo_dma_out_finish(fifo, len) \
-(void)({ \
-	typeof((fifo) + 1) __tmp = (fifo); \
-	unsigned int __len = (len); \
-	const size_t __recsize = sizeof(*__tmp->rectype); \
-	struct __kfifo *__kfifo = &__tmp->kfifo; \
-	if (__recsize) \
-		__kfifo_dma_out_finish_r(__kfifo, __recsize); \
-	else \
-		__kfifo->out += __len / sizeof(*__tmp->type); \
-})
+#define kfifo_dma_out_finish(fifo, len) do { \
+	typeof((fifo) + 1) ___tmp = (fifo); \
+	kfifo_skip_count(___tmp, (len) / sizeof(*___tmp->type)); \
+} while (0)
 
 /**
  * kfifo_out_peek - gets some data from the fifo
@@ -813,7 +823,7 @@ __kfifo_int_must_check_helper( \
  * @buf: pointer to the storage buffer
  * @n: max. number of elements to get
  *
- * This macro get the data from the fifo and return the numbers of elements
+ * This macro gets the data from the fifo and returns the numbers of elements
  * copied. The data is not removed from the fifo.
  *
  * Note that with only one concurrent reader and one concurrent
@@ -833,6 +843,63 @@ __kfifo_uint_must_check_helper( \
 }) \
 )
 
+/**
+ * kfifo_out_linear - gets a tail of/offset to available data
+ * @fifo: address of the fifo to be used
+ * @tail: pointer to an unsigned int to store the value of tail
+ * @n: max. number of elements to point at
+ *
+ * This macro obtains the offset (tail) to the available data in the fifo
+ * buffer and returns the
+ * numbers of elements available. It returns the available count till the end
+ * of data or till the end of the buffer. So that it can be used for linear
+ * data processing (like memcpy() of (@fifo->data + @tail) with count
+ * returned).
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define kfifo_out_linear(fifo, tail, n) \
+__kfifo_uint_must_check_helper( \
+({ \
+	typeof((fifo) + 1) __tmp = (fifo); \
+	unsigned int *__tail = (tail); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_out_linear_r(__kfifo, __tail, __n, __recsize) : \
+	__kfifo_out_linear(__kfifo, __tail, __n); \
+}) \
+)
+
+/**
+ * kfifo_out_linear_ptr - gets a pointer to the available data
+ * @fifo: address of the fifo to be used
+ * @ptr: pointer to data to store the pointer to tail
+ * @n: max. number of elements to point at
+ *
+ * Similarly to kfifo_out_linear(), this macro obtains the pointer to the
+ * available data in the fifo buffer and returns the numbers of elements
+ * available. It returns the available count till the end of available data or
+ * till the end of the buffer. So that it can be used for linear data
+ * processing (like memcpy() of @ptr with count returned).
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define kfifo_out_linear_ptr(fifo, ptr, n) \
+__kfifo_uint_must_check_helper( \
+({ \
+	typeof((fifo) + 1) ___tmp = (fifo); \
+	unsigned int ___tail; \
+	unsigned int ___n = kfifo_out_linear(___tmp, &___tail, (n)); \
+	*(ptr) = ___tmp->kfifo.data + ___tail * kfifo_esize(___tmp); \
+	___n; \
+}) \
+)
+
+
 extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
 	size_t esize, gfp_t gfp_mask);
 
@@ -854,14 +921,17 @@ extern int __kfifo_to_user(struct __kfifo *fifo,
 	void __user *to, unsigned long len, unsigned int *copied);
 
 extern unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
-	struct scatterlist *sgl, int nents, unsigned int len);
+	struct scatterlist *sgl, int nents, unsigned int len, dma_addr_t dma);
 
 extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
-	struct scatterlist *sgl, int nents, unsigned int len);
+	struct scatterlist *sgl, int nents, unsigned int len, dma_addr_t dma);
 
 extern unsigned int __kfifo_out_peek(struct __kfifo *fifo,
 	void *buf, unsigned int len);
 
+extern unsigned int __kfifo_out_linear(struct __kfifo *fifo,
+	unsigned int *tail, unsigned int n);
+
 extern unsigned int __kfifo_in_r(struct __kfifo *fifo,
 	const void *buf, unsigned int len, size_t recsize);
 
@@ -876,15 +946,15 @@ extern int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
 	unsigned long len, unsigned int *copied, size_t recsize);
 
 extern unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
-	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
+	dma_addr_t dma);
 
 extern void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
 	unsigned int len, size_t recsize);
 
 extern unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
-	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
-
-extern void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize);
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
+	dma_addr_t dma);
 
 extern unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize);
 
@@ -893,6 +963,9 @@ extern void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize);
 extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo,
 	void *buf, unsigned int len, size_t recsize);
 
+extern unsigned int __kfifo_out_linear_r(struct __kfifo *fifo,
+	unsigned int *tail, unsigned int n, size_t recsize);
+
 extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);
 
 #endif
diff --git a/include/linux/pnp.h b/include/linux/pnp.h
index ddbe7c3ca4ce..82561242cda4 100644
--- a/include/linux/pnp.h
+++ b/include/linux/pnp.h
@@ -469,6 +469,8 @@ int compare_pnp_id(struct pnp_id *pos, const char *id);
 int pnp_register_driver(struct pnp_driver *drv);
 void pnp_unregister_driver(struct pnp_driver *drv);
 
+#define dev_is_pnp(d) ((d)->bus == &pnp_bus_type)
+
 #else
 
 /* device management */
@@ -500,6 +502,8 @@ static inline int compare_pnp_id(struct pnp_id *pos, const char *id) { return -E
 static inline int pnp_register_driver(struct pnp_driver *drv) { return -ENODEV; }
 static inline void pnp_unregister_driver(struct pnp_driver *drv) { }
 
+#define dev_is_pnp(d) false
+
 #endif /* CONFIG_PNP */
 
 /**
diff --git a/include/linux/printk.h b/include/linux/printk.h
index dbbd202b1cb3..40afab23881a 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -60,6 +60,9 @@ static inline const char *printk_skip_headers(const char *buffer)
 #define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT
 #define CONSOLE_LOGLEVEL_QUIET	 CONFIG_CONSOLE_LOGLEVEL_QUIET
 
+int add_preferred_console_match(const char *match, const char *name,
+				const short idx);
+
 extern int console_printk[];
 
 #define console_loglevel (console_printk[0])
@@ -192,6 +195,7 @@ void show_regs_print_info(const char *log_lvl);
 extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold;
 extern asmlinkage void dump_stack(void) __cold;
 void printk_trigger_flush(void);
+void console_replay_all(void);
 #else
 static inline __printf(1, 0)
 int vprintk(const char *s, va_list args)
@@ -271,6 +275,9 @@ static inline void dump_stack(void)
 static inline void printk_trigger_flush(void)
 {
 }
+static inline void console_replay_all(void)
+{
+}
 #endif
 
 bool this_cpu_in_panic(void);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 0a0f6e21d40e..8cb65f50e830 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -11,7 +11,6 @@
 #include <linux/compiler.h>
 #include <linux/console.h>
 #include <linux/interrupt.h>
-#include <linux/circ_buf.h>
 #include <linux/spinlock.h>
 #include <linux/sched.h>
 #include <linux/tty.h>
@@ -699,7 +698,6 @@ struct uart_state {
 	struct tty_port		port;
 
 	enum uart_pm_state	pm_state;
-	struct circ_buf		xmit;
 
 	atomic_t		refcount;
 	wait_queue_head_t	remove_wait;
@@ -723,12 +721,35 @@ struct uart_state {
  */
 static inline void uart_xmit_advance(struct uart_port *up, unsigned int chars)
 {
-	struct circ_buf *xmit = &up->state->xmit;
+	struct tty_port *tport = &up->state->port;
 
-	xmit->tail = (xmit->tail + chars) & (UART_XMIT_SIZE - 1);
+	kfifo_skip_count(&tport->xmit_fifo, chars);
 	up->icount.tx += chars;
 }
 
+static inline unsigned int uart_fifo_out(struct uart_port *up,
+		unsigned char *buf, unsigned int chars)
+{
+	struct tty_port *tport = &up->state->port;
+
+	chars = kfifo_out(&tport->xmit_fifo, buf, chars);
+	up->icount.tx += chars;
+
+	return chars;
+}
+
+static inline unsigned int uart_fifo_get(struct uart_port *up,
+		unsigned char *ch)
+{
+	struct tty_port *tport = &up->state->port;
+	unsigned int chars;
+
+	chars = kfifo_get(&tport->xmit_fifo, ch);
+	up->icount.tx += chars;
+
+	return chars;
+}
+
 struct module;
 struct tty_driver;
 
@@ -764,7 +785,7 @@ enum UART_TX_FLAGS {
 		       for_test, for_post)				      \
 ({									      \
 	struct uart_port *__port = (uport);				      \
-	struct circ_buf *xmit = &__port->state->xmit;			      \
+	struct tty_port *__tport = &__port->state->port;		      \
 	unsigned int pending;						      \
 									      \
 	for (; (for_test) && (tx_ready); (for_post), __port->icount.tx++) {   \
@@ -775,17 +796,18 @@ enum UART_TX_FLAGS {
 			continue;					      \
 		}							      \
 									      \
-		if (uart_circ_empty(xmit) || uart_tx_stopped(__port))	      \
+		if (uart_tx_stopped(__port))				      \
+			break;						      \
+									      \
+		if (!kfifo_get(&__tport->xmit_fifo, &(ch)))		      \
 			break;						      \
 									      \
-		(ch) = xmit->buf[xmit->tail];				      \
 		(put_char);						      \
-		xmit->tail = (xmit->tail + 1) % UART_XMIT_SIZE;		      \
 	}								      \
 									      \
 	(tx_done);							      \
 									      \
-	pending = uart_circ_chars_pending(xmit);			      \
+	pending = kfifo_len(&__tport->xmit_fifo);			      \
 	if (pending < WAKEUP_CHARS) {					      \
 		uart_write_wakeup(__port);				      \
 									      \
@@ -974,15 +996,6 @@ bool uart_match_port(const struct uart_port *port1,
 int uart_suspend_port(struct uart_driver *reg, struct uart_port *port);
 int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
 
-#define uart_circ_empty(circ)		((circ)->head == (circ)->tail)
-#define uart_circ_clear(circ)		((circ)->head = (circ)->tail = 0)
-
-#define uart_circ_chars_pending(circ)	\
-	(CIRC_CNT((circ)->head, (circ)->tail, UART_XMIT_SIZE))
-
-#define uart_circ_chars_free(circ)	\
-	(CIRC_SPACE((circ)->head, (circ)->tail, UART_XMIT_SIZE))
-
 static inline int uart_tx_stopped(struct uart_port *port)
 {
 	struct tty_struct *tty = port->state->port.tty;
diff --git a/include/linux/serial_max3100.h b/include/linux/serial_max3100.h
deleted file mode 100644
index befd55c08a7c..000000000000
--- a/include/linux/serial_max3100.h
+++ /dev/null
@@ -1,48 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/*
- *
- *  Copyright (C) 2007 Christian Pellegrin
- */
-
-
-#ifndef _LINUX_SERIAL_MAX3100_H
-#define _LINUX_SERIAL_MAX3100_H 1
-
-
-/**
- * struct plat_max3100 - MAX3100 SPI UART platform data
- * @loopback:            force MAX3100 in loopback
- * @crystal:             1 for 3.6864 Mhz, 0 for 1.8432
- * @max3100_hw_suspend:  MAX3100 has a shutdown pin. This is a hook
- *                       called on suspend and resume to activate it.
- * @poll_time:           poll time for CTS signal in ms, 0 disables (so no hw
- *                       flow ctrl is possible but you have less CPU usage)
- *
- * You should use this structure in your machine description to specify
- * how the MAX3100 is connected. Example:
- *
- * static struct plat_max3100 max3100_plat_data = {
- *  .loopback = 0,
- *  .crystal = 0,
- *  .poll_time = 100,
- * };
- *
- * static struct spi_board_info spi_board_info[] = {
- * {
- *  .modalias	= "max3100",
- *  .platform_data	= &max3100_plat_data,
- *  .irq		= IRQ_EINT12,
- *  .max_speed_hz	= 5*1000*1000,
- *  .chip_select	= 0,
- * },
- * };
- *
- **/
-struct plat_max3100 {
-	int loopback;
-	int crystal;
-	void (*max3100_hw_suspend) (int suspend);
-	int poll_time;
-};
-
-#endif
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 7372124fbf90..dd4b31ce6d5d 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -154,6 +154,13 @@ struct serial_struct;
  *
  *	Optional. Called under the @tty->termios_rwsem. May sleep.
  *
+ * @ldisc_ok: ``int ()(struct tty_struct *tty, int ldisc)``
+ *
+ *	This routine allows the @tty driver to decide if it can deal
+ *	with a particular @ldisc.
+ *
+ *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
+ *
  * @set_ldisc: ``void ()(struct tty_struct *tty)``
  *
  *	This routine allows the @tty driver to be notified when the device's
@@ -372,6 +379,7 @@ struct tty_operations {
 	void (*hangup)(struct tty_struct *tty);
 	int (*break_ctl)(struct tty_struct *tty, int state);
 	void (*flush_buffer)(struct tty_struct *tty);
+	int (*ldisc_ok)(struct tty_struct *tty, int ldisc);
 	void (*set_ldisc)(struct tty_struct *tty);
 	void (*wait_until_sent)(struct tty_struct *tty, int timeout);
 	void (*send_xchar)(struct tty_struct *tty, u8 ch);