From be2e2cb1d28195792539ac2539f8c40c39d3dd4c Mon Sep 17 00:00:00 2001
From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Date: Mon, 6 Jun 2022 13:04:19 +0300
Subject: serial: Sanitize rs485_struct
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Sanitize serial_rs485 struct before calling into rs485_setup. The
drivers provide supported_rs485 to help sanitization of the fields.

If neither of SER_RS485_RTS_ON_SEND or SER_RS485_RTS_AFTER_SEND
supported, don't pretend they can be set to sane settings but clear
them both instead. If only one of them is supported it may look
tempting to use the one driver supports to set the other, however, the
userspace does not have that information readily available so it
wouldn't be helpful.

While adjusting the documentation, remove also the claim that
TIOCGRS485 would call driver specific code. In reality, it does nothing
else than copies the stored serial_rs485 structure from uart_port to
userspace.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-23-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/serial-rs485.rst | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/serial-rs485.rst b/Documentation/driver-api/serial/serial-rs485.rst
index 6bc824f948f9..00b5d333acba 100644
--- a/Documentation/driver-api/serial/serial-rs485.rst
+++ b/Documentation/driver-api/serial/serial-rs485.rst
@@ -38,10 +38,14 @@ RS485 Serial Communications
    the values given by the device tree.
 
    Any driver for devices capable of working both as RS232 and RS485 should
-   implement the rs485_config callback in the uart_port structure. The
-   serial_core calls rs485_config to do the device specific part in response
-   to TIOCSRS485 and TIOCGRS485 ioctls (see below). The rs485_config callback
-   receives a pointer to struct serial_rs485.
+   implement the rs485_config callback and provide rs485_supported in the
+   uart_port structure. The serial core calls rs485_config to do the device
+   specific part in response to TIOCSRS485 ioctl (see below). The rs485_config
+   callback receives a pointer to a sanitizated serial_rs485 structure. The
+   serial_rs485 userspace provides is sanitized before calling rs485_config
+   using rs485_supported that indicates what RS485 features the driver supports
+   for the uart_port. TIOCGRS485 ioctl can be used to read back the
+   serial_rs485 structure matching to the current configuration.
 
 4. Usage from user-level
 ========================
-- 
cgit v1.2.3-59-g8ed1b


From f9008285bb69e4713918a665250ab2d356b731ba Mon Sep 17 00:00:00 2001
From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Date: Mon, 13 Jun 2022 14:39:05 +0300
Subject: serial: Drop timeout from uart_port
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Since commit 31f6bd7fad3b ("serial: Store character timing information
to uart_port"), per frame timing information is available on uart_port.
Uart port's timeout can be derived from frame_time by multiplying with
fifosize.

Most callers of uart_poll_timeout are not made under port's lock. To be
on the safe side, make sure frame_time is only accessed once. As
fifo_size is effectively a constant, it shouldn't cause any issues.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220613113905.22962-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst |  5 +++--
 drivers/tty/serial/mux.c                   |  6 ------
 drivers/tty/serial/serial_core.c           | 25 ++++++++++---------------
 include/linux/serial_core.h                | 16 ++++++++++++++--
 4 files changed, 27 insertions(+), 25 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index 7ef83fd3917b..1e7ab4142d49 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -422,8 +422,9 @@ Other functions
 ---------------
 
 uart_update_timeout(port,cflag,baud)
-	Update the FIFO drain timeout, port->timeout, according to the
-	number of bits, parity, stop bits and baud rate.
+	Update the frame timing information according to the number of bits,
+	parity, stop bits and baud rate. The FIFO drain timeout is derived
+	from the frame timing information.
 
 	Locking: caller is expected to take port->lock
 
diff --git a/drivers/tty/serial/mux.c b/drivers/tty/serial/mux.c
index 643dfbcc43f9..0ba0f4d9459d 100644
--- a/drivers/tty/serial/mux.c
+++ b/drivers/tty/serial/mux.c
@@ -481,12 +481,6 @@ static int __init mux_probe(struct parisc_device *dev)
 		port->line	= port_cnt;
 		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_MUX_CONSOLE);
 
-		/* The port->timeout needs to match what is present in
-		 * uart_wait_until_sent in serial_core.c.  Otherwise
-		 * the time spent in msleep_interruptable will be very
-		 * long, causing the appearance of a console hang.
-		 */
-		port->timeout   = HZ / 50;
 		spin_lock_init(&port->lock);
 
 		status = uart_add_one_port(&mux_driver, port);
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 1368b0ef7d7f..75ece750bedc 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -327,13 +327,14 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 }
 
 /**
- *	uart_update_timeout - update per-port FIFO timeout.
+ *	uart_update_timeout - update per-port frame timing information.
  *	@port:  uart_port structure describing the port
  *	@cflag: termios cflag value
  *	@baud:  speed of the port
  *
- *	Set the port FIFO timeout value.  The @cflag value should
- *	reflect the actual hardware settings.
+ *	Set the port frame timing information from which the FIFO timeout
+ *	value is derived. The @cflag value should reflect the actual hardware
+ *	settings.
  */
 void
 uart_update_timeout(struct uart_port *port, unsigned int cflag,
@@ -343,13 +344,6 @@ uart_update_timeout(struct uart_port *port, unsigned int cflag,
 	u64 frame_time;
 
 	frame_time = (u64)size * NSEC_PER_SEC;
-	size *= port->fifosize;
-
-	/*
-	 * Figure the timeout to send the above number of bits.
-	 * Add .02 seconds of slop
-	 */
-	port->timeout = (HZ * size) / baud + HZ/50;
 	port->frame_time = DIV64_U64_ROUND_UP(frame_time, baud);
 }
 EXPORT_SYMBOL(uart_update_timeout);
@@ -1698,7 +1692,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
 {
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port;
-	unsigned long char_time, expire;
+	unsigned long char_time, expire, fifo_timeout;
 
 	port = uart_port_ref(state);
 	if (!port)
@@ -1728,12 +1722,13 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
 		 * amount of time to send the entire FIFO, it probably won't
 		 * ever clear.  This assumes the UART isn't doing flow
 		 * control, which is currently the case.  Hence, if it ever
-		 * takes longer than port->timeout, this is probably due to a
+		 * takes longer than FIFO timeout, this is probably due to a
 		 * UART bug of some kind.  So, we clamp the timeout parameter at
-		 * 2*port->timeout.
+		 * 2 * FIFO timeout.
 		 */
-		if (timeout == 0 || timeout > 2 * port->timeout)
-			timeout = 2 * port->timeout;
+		fifo_timeout = uart_fifo_timeout(port);
+		if (timeout == 0 || timeout > 2 * fifo_timeout)
+			timeout = 2 * fifo_timeout;
 	}
 
 	expire = jiffies + timeout;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 8032ffa741ed..faaf2372c60d 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -232,7 +232,6 @@ struct uart_port {
 
 	int			hw_stopped;		/* sw-assisted CTS flow state */
 	unsigned int		mctrl;			/* current modem ctrl settings */
-	unsigned int		timeout;		/* character-based timeout */
 	unsigned int		frame_time;		/* frame timing in ns */
 	unsigned int		type;			/* port type */
 	const struct uart_ops	*ops;
@@ -335,10 +334,23 @@ unsigned int uart_get_baud_rate(struct uart_port *port, struct ktermios *termios
 				unsigned int max);
 unsigned int uart_get_divisor(struct uart_port *port, unsigned int baud);
 
+/*
+ * Calculates FIFO drain time.
+ */
+static inline unsigned long uart_fifo_timeout(struct uart_port *port)
+{
+	u64 fifo_timeout = (u64)READ_ONCE(port->frame_time) * port->fifosize;
+
+	/* Add .02 seconds of slop */
+	fifo_timeout += 20 * NSEC_PER_MSEC;
+
+	return max(nsecs_to_jiffies(fifo_timeout), 1UL);
+}
+
 /* Base timer interval for polling */
 static inline int uart_poll_timeout(struct uart_port *port)
 {
-	int timeout = port->timeout;
+	int timeout = uart_fifo_timeout(port);
 
 	return timeout > 6 ? (timeout / 2 - 2) : 1;
 }
-- 
cgit v1.2.3-59-g8ed1b


From 4f768e94774c58c9f7f54ebd38dadf172970046a Mon Sep 17 00:00:00 2001
From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Date: Fri, 24 Jun 2022 23:42:09 +0300
Subject: serial: Support for RS-485 multipoint addresses
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().

ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.

Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().

[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst       |  2 ++
 Documentation/driver-api/serial/serial-rs485.rst | 26 +++++++++++++++++++++++-
 drivers/tty/serial/serial_core.c                 | 22 +++++++++++++++++++-
 drivers/tty/tty_ioctl.c                          |  4 ++++
 include/uapi/asm-generic/termbits-common.h       |  1 +
 include/uapi/linux/serial.h                      | 20 ++++++++++++++++--
 6 files changed, 71 insertions(+), 4 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index 1e7ab4142d49..ee1679858aa2 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -261,6 +261,8 @@ hardware.
 			- parity enable
 		PARODD
 			- odd parity (when PARENB is in force)
+		ADDRB
+			- address bit (changed through .rs485_config()).
 		CREAD
 			- enable reception of characters (if not set,
 			  still receive characters from the port, but
diff --git a/Documentation/driver-api/serial/serial-rs485.rst b/Documentation/driver-api/serial/serial-rs485.rst
index 00b5d333acba..6ebad75c74ed 100644
--- a/Documentation/driver-api/serial/serial-rs485.rst
+++ b/Documentation/driver-api/serial/serial-rs485.rst
@@ -99,7 +99,31 @@ RS485 Serial Communications
 		/* Error handling. See errno. */
 	}
 
-5. References
+5. Multipoint Addressing
+========================
+
+   The Linux kernel provides addressing mode for multipoint RS-485 serial
+   communications line. The addressing mode is enabled with SER_RS485_ADDRB
+   flag in serial_rs485. Struct serial_rs485 has two additional flags and
+   fields for enabling receive and destination addresses.
+
+   Address mode flags:
+	- SER_RS485_ADDRB: Enabled addressing mode (sets also ADDRB in termios).
+	- SER_RS485_ADDR_RECV: Receive (filter) address enabled.
+	- SER_RS485_ADDR_DEST: Set destination address.
+
+   Address fields (enabled with corresponding SER_RS485_ADDR_* flag):
+	- addr_recv: Receive address.
+	- addr_dest: Destination address.
+
+   Once a receive address is set, the communication can occur only with the
+   particular device and other peers are filtered out. It is left up to the
+   receiver side to enforce the filtering. Receive address will be cleared
+   if SER_RS485_ADDR_RECV is not set.
+
+   Note: not all devices supporting RS485 support multipoint addressing.
+
+6. References
 =============
 
  [1]	include/uapi/linux/serial.h
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 2529153c8979..85ef7ef00b82 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1288,6 +1288,17 @@ static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *r
 	if (flags & ~port->rs485_supported->flags)
 		return -EINVAL;
 
+	/* Asking for address w/o addressing mode? */
+	if (!(rs485->flags & SER_RS485_ADDRB) &&
+	    (rs485->flags & (SER_RS485_ADDR_RECV|SER_RS485_ADDR_DEST)))
+		return -EINVAL;
+
+	/* Address given but not enabled? */
+	if (!(rs485->flags & SER_RS485_ADDR_RECV) && rs485->addr_recv)
+		return -EINVAL;
+	if (!(rs485->flags & SER_RS485_ADDR_DEST) && rs485->addr_dest)
+		return -EINVAL;
+
 	return 0;
 }
 
@@ -1343,7 +1354,8 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
 	rs485->flags &= supported_flags;
 
 	/* Return clean padding area to userspace */
-	memset(rs485->padding, 0, sizeof(rs485->padding));
+	memset(rs485->padding0, 0, sizeof(rs485->padding0));
+	memset(rs485->padding1, 0, sizeof(rs485->padding1));
 }
 
 int uart_rs485_config(struct uart_port *port)
@@ -3402,5 +3414,13 @@ int uart_get_rs485_mode(struct uart_port *port)
 }
 EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
 
+/* Compile-time assertions for serial_rs485 layout */
+static_assert(offsetof(struct serial_rs485, padding) ==
+              (offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
+static_assert(offsetof(struct serial_rs485, padding1) ==
+	      offsetof(struct serial_rs485, padding[1]));
+static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
+	      sizeof(struct serial_rs485));
+
 MODULE_DESCRIPTION("Serial driver core");
 MODULE_LICENSE("GPL");
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index adae687f654b..2a76b330e108 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -319,6 +319,8 @@ unsigned char tty_get_frame_size(unsigned int cflag)
 		bits++;
 	if (cflag & PARENB)
 		bits++;
+	if (cflag & ADDRB)
+		bits++;
 
 	return bits;
 }
@@ -353,6 +355,8 @@ int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
 	old_termios = tty->termios;
 	tty->termios = *new_termios;
 	unset_locked_termios(tty, &old_termios);
+	/* Reset any ADDRB changes, ADDRB is changed through ->rs485_config() */
+	tty->termios.c_cflag ^= (tty->termios.c_cflag ^ old_termios.c_cflag) & ADDRB;
 
 	if (tty->ops->set_termios)
 		tty->ops->set_termios(tty, &old_termios);
diff --git a/include/uapi/asm-generic/termbits-common.h b/include/uapi/asm-generic/termbits-common.h
index 4d084fe8def5..4a6a79f28b21 100644
--- a/include/uapi/asm-generic/termbits-common.h
+++ b/include/uapi/asm-generic/termbits-common.h
@@ -46,6 +46,7 @@ typedef unsigned int	speed_t;
 #define EXTA		B19200
 #define EXTB		B38400
 
+#define ADDRB		0x20000000	/* address bit */
 #define CMSPAR		0x40000000	/* mark or space (stick) parity */
 #define CRTSCTS		0x80000000	/* flow control */
 
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index fa6b16e5fdd8..cea06924b295 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -126,10 +126,26 @@ struct serial_rs485 {
 #define SER_RS485_TERMINATE_BUS		(1 << 5)	/* Enable bus
 							   termination
 							   (if supported) */
+
+/* RS-485 addressing mode */
+#define SER_RS485_ADDRB			(1 << 6)	/* Enable addressing mode */
+#define SER_RS485_ADDR_RECV		(1 << 7)	/* Receive address filter */
+#define SER_RS485_ADDR_DEST		(1 << 8)	/* Destination address */
+
 	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
 	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
-	__u32	padding[5];		/* Memory is cheap, new structs
-					   are a royal PITA .. */
+
+	/* The fields below are defined by flags */
+	union {
+		__u32	padding[5];		/* Memory is cheap, new structs are a pain */
+
+		struct {
+			__u8	addr_recv;
+			__u8	addr_dest;
+			__u8	padding0[2];
+			__u32	padding1[4];
+		};
+	};
 };
 
 /*
-- 
cgit v1.2.3-59-g8ed1b


From e60a7233684aa8bbe9090537720fe6a1e901d823 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 28 Jul 2022 08:10:51 +0200
Subject: Documentation: serial: move uart_ops documentation to the struct

While it's a lot of text, it always helps to keep it up to date when
it's by the source. (And not in a separate file.)

The documentation tooling also makes sure that all members of the
structure are documented. (If not, it complains loudly.)

Finally, there needs to be no comments inlined in the structure, so they
are dropped as they are superfluous now.

The compilation time of this header (tested with serial_core.c) didn't
change in my testing at all.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst | 358 +----------------------------
 include/linux/serial_core.h                | 345 +++++++++++++++++++++++++--
 2 files changed, 331 insertions(+), 372 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index ee1679858aa2..cb0ec6db4f1e 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -63,362 +63,8 @@ commonly referred to as the port mutex.
 uart_ops
 --------
 
-The uart_ops structure is the main interface between serial_core and the
-hardware specific driver.  It contains all the methods to control the
-hardware.
-
-  tx_empty(port)
-	This function tests whether the transmitter fifo and shifter
-	for the port described by 'port' is empty.  If it is empty,
-	this function should return TIOCSER_TEMT, otherwise return 0.
-	If the port does not support this operation, then it should
-	return TIOCSER_TEMT.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-	This call must not sleep
-
-  set_mctrl(port, mctrl)
-	This function sets the modem control lines for port described
-	by 'port' to the state described by mctrl.  The relevant bits
-	of mctrl are:
-
-		- TIOCM_RTS	RTS signal.
-		- TIOCM_DTR	DTR signal.
-		- TIOCM_OUT1	OUT1 signal.
-		- TIOCM_OUT2	OUT2 signal.
-		- TIOCM_LOOP	Set the port into loopback mode.
-
-	If the appropriate bit is set, the signal should be driven
-	active.  If the bit is clear, the signal should be driven
-	inactive.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  get_mctrl(port)
-	Returns the current state of modem control inputs.  The state
-	of the outputs should not be returned, since the core keeps
-	track of their state.  The state information should include:
-
-		- TIOCM_CAR	state of DCD signal
-		- TIOCM_CTS	state of CTS signal
-		- TIOCM_DSR	state of DSR signal
-		- TIOCM_RI	state of RI signal
-
-	The bit is set if the signal is currently driven active.  If
-	the port does not support CTS, DCD or DSR, the driver should
-	indicate that the signal is permanently active.  If RI is
-	not available, the signal should not be indicated as active.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  stop_tx(port)
-	Stop transmitting characters.  This might be due to the CTS
-	line becoming inactive or the tty layer indicating we want
-	to stop transmission due to an XOFF character.
-
-	The driver should stop transmitting characters as soon as
-	possible.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  start_tx(port)
-	Start transmitting characters.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  throttle(port)
-	Notify the serial driver that input buffers for the line discipline are
-	close to full, and it should somehow signal that no more characters
-	should be sent to the serial port.
-	This will be called only if hardware assisted flow control is enabled.
-
-	Locking: serialized with .unthrottle() and termios modification by the
-	tty layer.
-
-  unthrottle(port)
-	Notify the serial driver that characters can now be sent to the serial
-	port without fear of overrunning the input buffers of the line
-	disciplines.
-
-	This will be called only if hardware assisted flow control is enabled.
-
-	Locking: serialized with .throttle() and termios modification by the
-	tty layer.
-
-  send_xchar(port,ch)
-	Transmit a high priority character, even if the port is stopped.
-	This is used to implement XON/XOFF flow control and tcflow().  If
-	the serial driver does not implement this function, the tty core
-	will append the character to the circular buffer and then call
-	start_tx() / stop_tx() to flush the data out.
-
-	Do not transmit if ch == '\0' (__DISABLED_CHAR).
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  stop_rx(port)
-	Stop receiving characters; the port is in the process of
-	being closed.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  enable_ms(port)
-	Enable the modem status interrupts.
-
-	This method may be called multiple times.  Modem status
-	interrupts should be disabled when the shutdown method is
-	called.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  break_ctl(port,ctl)
-	Control the transmission of a break signal.  If ctl is
-	nonzero, the break signal should be transmitted.  The signal
-	should be terminated when another call is made with a zero
-	ctl.
-
-	Locking: caller holds tty_port->mutex
-
-  startup(port)
-	Grab any interrupt resources and initialise any low level driver
-	state.  Enable the port for reception.  It should not activate
-	RTS nor DTR; this will be done via a separate call to set_mctrl.
-
-	This method will only be called when the port is initially opened.
-
-	Locking: port_sem taken.
-
-	Interrupts: globally disabled.
-
-  shutdown(port)
-	Disable the port, disable any break condition that may be in
-	effect, and free any interrupt resources.  It should not disable
-	RTS nor DTR; this will have already been done via a separate
-	call to set_mctrl.
-
-	Drivers must not access port->state once this call has completed.
-
-	This method will only be called when there are no more users of
-	this port.
-
-	Locking: port_sem taken.
-
-	Interrupts: caller dependent.
-
-  flush_buffer(port)
-	Flush any write buffers, reset any DMA state and stop any
-	ongoing DMA transfers.
-
-	This will be called whenever the port->state->xmit circular
-	buffer is cleared.
-
-	Locking: port->lock taken.
-
-	Interrupts: locally disabled.
-
-	This call must not sleep
-
-  set_termios(port,termios,oldtermios)
-	Change the port parameters, including word length, parity, stop
-	bits.  Update read_status_mask and ignore_status_mask to indicate
-	the types of events we are interested in receiving.  Relevant
-	termios->c_cflag bits are:
-
-		CSIZE
-			- word size
-		CSTOPB
-			- 2 stop bits
-		PARENB
-			- parity enable
-		PARODD
-			- odd parity (when PARENB is in force)
-		ADDRB
-			- address bit (changed through .rs485_config()).
-		CREAD
-			- enable reception of characters (if not set,
-			  still receive characters from the port, but
-			  throw them away.
-		CRTSCTS
-			- if set, enable CTS status change reporting
-		CLOCAL
-			- if not set, enable modem status change
-			  reporting.
-
-	Relevant termios->c_iflag bits are:
-
-		INPCK
-			- enable frame and parity error events to be
-			  passed to the TTY layer.
-		BRKINT / PARMRK
-			- both of these enable break events to be
-			  passed to the TTY layer.
-
-		IGNPAR
-			- ignore parity and framing errors
-		IGNBRK
-			- ignore break errors,  If IGNPAR is also
-			  set, ignore overrun errors as well.
-
-	The interaction of the iflag bits is as follows (parity error
-	given as an example):
-
-	=============== ======= ======  =============================
-	Parity error	INPCK	IGNPAR
-	=============== ======= ======  =============================
-	n/a		0	n/a	character received, marked as
-					TTY_NORMAL
-	None		1	n/a	character received, marked as
-					TTY_NORMAL
-	Yes		1	0	character received, marked as
-					TTY_PARITY
-	Yes		1	1	character discarded
-	=============== ======= ======  =============================
-
-	Other flags may be used (eg, xon/xoff characters) if your
-	hardware supports hardware "soft" flow control.
-
-	Locking: caller holds tty_port->mutex
-
-	Interrupts: caller dependent.
-
-	This call must not sleep
-
-  set_ldisc(port,termios)
-	Notifier for discipline change. See ../tty/tty_ldisc.rst.
-
-	Locking: caller holds tty_port->mutex
-
-  pm(port,state,oldstate)
-	Perform any power management related activities on the specified
-	port.  State indicates the new state (defined by
-	enum uart_pm_state), oldstate indicates the previous state.
-
-	This function should not be used to grab any resources.
-
-	This will be called when the port is initially opened and finally
-	closed, except when the port is also the system console.  This
-	will occur even if CONFIG_PM is not set.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  type(port)
-	Return a pointer to a string constant describing the specified
-	port, or return NULL, in which case the string 'unknown' is
-	substituted.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  release_port(port)
-	Release any memory and IO region resources currently in use by
-	the port.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  request_port(port)
-	Request any memory and IO region resources required by the port.
-	If any fail, no resources should be registered when this function
-	returns, and it should return -EBUSY on failure.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  config_port(port,type)
-	Perform any autoconfiguration steps required for the port.  `type`
-	contains a bit mask of the required configuration.  UART_CONFIG_TYPE
-	indicates that the port requires detection and identification.
-	port->type should be set to the type found, or PORT_UNKNOWN if
-	no port was detected.
-
-	UART_CONFIG_IRQ indicates autoconfiguration of the interrupt signal,
-	which should be probed using standard kernel autoprobing techniques.
-	This is not necessary on platforms where ports have interrupts
-	internally hard wired (eg, system on a chip implementations).
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  verify_port(port,serinfo)
-	Verify the new serial port information contained within serinfo is
-	suitable for this port type.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  ioctl(port,cmd,arg)
-	Perform any port specific IOCTLs.  IOCTL commands must be defined
-	using the standard numbering system found in <asm/ioctl.h>
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-  poll_init(port)
-	Called by kgdb to perform the minimal hardware initialization needed
-	to support poll_put_char() and poll_get_char().  Unlike ->startup()
-	this should not request interrupts.
-
-	Locking: tty_mutex and tty_port->mutex taken.
-
-	Interrupts: n/a.
-
-  poll_put_char(port,ch)
-	Called by kgdb to write a single character directly to the serial
-	port.  It can and should block until there is space in the TX FIFO.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-	This call must not sleep
-
-  poll_get_char(port)
-	Called by kgdb to read a single character directly from the serial
-	port.  If data is available, it should be returned; otherwise
-	the function should return NO_POLL_CHAR immediately.
-
-	Locking: none.
-
-	Interrupts: caller dependent.
-
-	This call must not sleep
+.. kernel-doc:: include/linux/serial_core.h
+   :identifiers: uart_ops
 
 Other functions
 ---------------
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index a6fa7c40c330..35d2f9e8027d 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -31,9 +31,336 @@ struct serial_struct;
 struct device;
 struct gpio_desc;
 
-/*
+/**
+ * struct uart_ops -- interface between serial_core and the driver
+ *
  * This structure describes all the operations that can be done on the
- * physical hardware.  See Documentation/driver-api/serial/driver.rst for details.
+ * physical hardware.
+ *
+ * @tx_empty: ``unsigned int ()(struct uart_port *port)``
+ *
+ *	This function tests whether the transmitter fifo and shifter for the
+ *	@port is empty. If it is empty, this function should return
+ *	%TIOCSER_TEMT, otherwise return 0. If the port does not support this
+ *	operation, then it should return %TIOCSER_TEMT.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *	This call must not sleep
+ *
+ * @set_mctrl: ``void ()(struct uart_port *port, unsigned int mctrl)``
+ *
+ *	This function sets the modem control lines for @port to the state
+ *	described by @mctrl. The relevant bits of @mctrl are:
+ *
+ *		- %TIOCM_RTS	RTS signal.
+ *		- %TIOCM_DTR	DTR signal.
+ *		- %TIOCM_OUT1	OUT1 signal.
+ *		- %TIOCM_OUT2	OUT2 signal.
+ *		- %TIOCM_LOOP	Set the port into loopback mode.
+ *
+ *	If the appropriate bit is set, the signal should be driven
+ *	active.  If the bit is clear, the signal should be driven
+ *	inactive.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @get_mctrl: ``unsigned int ()(struct uart_port *port)``
+ *
+ *	Returns the current state of modem control inputs of @port. The state
+ *	of the outputs should not be returned, since the core keeps track of
+ *	their state. The state information should include:
+ *
+ *		- %TIOCM_CAR	state of DCD signal
+ *		- %TIOCM_CTS	state of CTS signal
+ *		- %TIOCM_DSR	state of DSR signal
+ *		- %TIOCM_RI	state of RI signal
+ *
+ *	The bit is set if the signal is currently driven active.  If
+ *	the port does not support CTS, DCD or DSR, the driver should
+ *	indicate that the signal is permanently active. If RI is
+ *	not available, the signal should not be indicated as active.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @stop_tx: ``void ()(struct uart_port *port)``
+ *
+ *	Stop transmitting characters. This might be due to the CTS line
+ *	becoming inactive or the tty layer indicating we want to stop
+ *	transmission due to an %XOFF character.
+ *
+ *	The driver should stop transmitting characters as soon as possible.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @start_tx: ``void ()(struct uart_port *port)``
+ *
+ *	Start transmitting characters.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @throttle: ``void ()(struct uart_port *port)``
+ *
+ *	Notify the serial driver that input buffers for the line discipline are
+ *	close to full, and it should somehow signal that no more characters
+ *	should be sent to the serial port.
+ *	This will be called only if hardware assisted flow control is enabled.
+ *
+ *	Locking: serialized with @unthrottle() and termios modification by the
+ *	tty layer.
+ *
+ * @unthrottle: ``void ()(struct uart_port *port)``
+ *
+ *	Notify the serial driver that characters can now be sent to the serial
+ *	port without fear of overrunning the input buffers of the line
+ *	disciplines.
+ *
+ *	This will be called only if hardware assisted flow control is enabled.
+ *
+ *	Locking: serialized with @throttle() and termios modification by the
+ *	tty layer.
+ *
+ * @send_xchar: ``void ()(struct uart_port *port, char ch)``
+ *
+ *	Transmit a high priority character, even if the port is stopped. This
+ *	is used to implement XON/XOFF flow control and tcflow(). If the serial
+ *	driver does not implement this function, the tty core will append the
+ *	character to the circular buffer and then call start_tx() / stop_tx()
+ *	to flush the data out.
+ *
+ *	Do not transmit if @ch == '\0' (%__DISABLED_CHAR).
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @stop_rx: ``void ()(struct uart_port *port)``
+ *
+ *	Stop receiving characters; the @port is in the process of being closed.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @enable_ms: ``void ()(struct uart_port *port)``
+ *
+ *	Enable the modem status interrupts.
+ *
+ *	This method may be called multiple times. Modem status interrupts
+ *	should be disabled when the @shutdown() method is called.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @break_ctl: ``void ()(struct uart_port *port, int ctl)``
+ *
+ *	Control the transmission of a break signal. If @ctl is nonzero, the
+ *	break signal should be transmitted. The signal should be terminated
+ *	when another call is made with a zero @ctl.
+ *
+ *	Locking: caller holds tty_port->mutex
+ *
+ * @startup: ``int ()(struct uart_port *port)``
+ *
+ *	Grab any interrupt resources and initialise any low level driver state.
+ *	Enable the port for reception. It should not activate RTS nor DTR;
+ *	this will be done via a separate call to @set_mctrl().
+ *
+ *	This method will only be called when the port is initially opened.
+ *
+ *	Locking: port_sem taken.
+ *	Interrupts: globally disabled.
+ *
+ * @shutdown: ``void ()(struct uart_port *port)``
+ *
+ *	Disable the @port, disable any break condition that may be in effect,
+ *	and free any interrupt resources. It should not disable RTS nor DTR;
+ *	this will have already been done via a separate call to @set_mctrl().
+ *
+ *	Drivers must not access @port->state once this call has completed.
+ *
+ *	This method will only be called when there are no more users of this
+ *	@port.
+ *
+ *	Locking: port_sem taken.
+ *	Interrupts: caller dependent.
+ *
+ * @flush_buffer: ``void ()(struct uart_port *port)``
+ *
+ *	Flush any write buffers, reset any DMA state and stop any ongoing DMA
+ *	transfers.
+ *
+ *	This will be called whenever the @port->state->xmit circular buffer is
+ *	cleared.
+ *
+ *	Locking: @port->lock taken.
+ *	Interrupts: locally disabled.
+ *	This call must not sleep
+ *
+ * @set_termios: ``void ()(struct uart_port *port, struct ktermios *new,
+ *			struct ktermios *old)``
+ *
+ *	Change the @port parameters, including word length, parity, stop bits.
+ *	Update @port->read_status_mask and @port->ignore_status_mask to
+ *	indicate the types of events we are interested in receiving. Relevant
+ *	ktermios::c_cflag bits are:
+ *
+ *	- %CSIZE - word size
+ *	- %CSTOPB - 2 stop bits
+ *	- %PARENB - parity enable
+ *	- %PARODD - odd parity (when %PARENB is in force)
+ *	- %ADDRB - address bit (changed through uart_port::rs485_config()).
+ *	- %CREAD - enable reception of characters (if not set, still receive
+ *	  characters from the port, but throw them away).
+ *	- %CRTSCTS - if set, enable CTS status change reporting.
+ *	- %CLOCAL - if not set, enable modem status change reporting.
+ *
+ *	Relevant ktermios::c_iflag bits are:
+ *
+ *	- %INPCK - enable frame and parity error events to be passed to the TTY
+ *	  layer.
+ *	- %BRKINT / %PARMRK - both of these enable break events to be passed to
+ *	  the TTY layer.
+ *	- %IGNPAR - ignore parity and framing errors.
+ *	- %IGNBRK - ignore break errors. If %IGNPAR is also set, ignore overrun
+ *	  errors as well.
+ *
+ *	The interaction of the ktermios::c_iflag bits is as follows (parity
+ *	error given as an example):
+ *
+ *	============ ======= ======= =========================================
+ *	Parity error INPCK   IGNPAR
+ *	============ ======= ======= =========================================
+ *	n/a	     0	     n/a     character received, marked as %TTY_NORMAL
+ *	None	     1	     n/a     character received, marked as %TTY_NORMAL
+ *	Yes	     1	     0	     character received, marked as %TTY_PARITY
+ *	Yes	     1	     1	     character discarded
+ *	============ ======= ======= =========================================
+ *
+ *	Other flags may be used (eg, xon/xoff characters) if your hardware
+ *	supports hardware "soft" flow control.
+ *
+ *	Locking: caller holds tty_port->mutex
+ *	Interrupts: caller dependent.
+ *	This call must not sleep
+ *
+ * @set_ldisc: ``void ()(struct uart_port *port, struct ktermios *termios)``
+ *
+ *	Notifier for discipline change. See
+ *	Documentation/driver-api/tty/tty_ldisc.rst.
+ *
+ *	Locking: caller holds tty_port->mutex
+ *
+ * @pm: ``void ()(struct uart_port *port, unsigned int state,
+ *		 unsigned int oldstate)``
+ *
+ *	Perform any power management related activities on the specified @port.
+ *	@state indicates the new state (defined by enum uart_pm_state),
+ *	@oldstate indicates the previous state.
+ *
+ *	This function should not be used to grab any resources.
+ *
+ *	This will be called when the @port is initially opened and finally
+ *	closed, except when the @port is also the system console. This will
+ *	occur even if %CONFIG_PM is not set.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @type: ``const char *()(struct uart_port *port)``
+ *
+ *	Return a pointer to a string constant describing the specified @port,
+ *	or return %NULL, in which case the string 'unknown' is substituted.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @release_port: ``void ()(struct uart_port *port)``
+ *
+ *	Release any memory and IO region resources currently in use by the
+ *	@port.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @request_port: ``int ()(struct uart_port *port)``
+ *
+ *	Request any memory and IO region resources required by the port. If any
+ *	fail, no resources should be registered when this function returns, and
+ *	it should return -%EBUSY on failure.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @config_port: ``void ()(struct uart_port *port, int type)``
+ *
+ *	Perform any autoconfiguration steps required for the @port. @type
+ *	contains a bit mask of the required configuration. %UART_CONFIG_TYPE
+ *	indicates that the port requires detection and identification.
+ *	@port->type should be set to the type found, or %PORT_UNKNOWN if no
+ *	port was detected.
+ *
+ *	%UART_CONFIG_IRQ indicates autoconfiguration of the interrupt signal,
+ *	which should be probed using standard kernel autoprobing techniques.
+ *	This is not necessary on platforms where ports have interrupts
+ *	internally hard wired (eg, system on a chip implementations).
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @verify_port: ``int ()(struct uart_port *port,
+ *			struct serial_struct *serinfo)``
+ *
+ *	Verify the new serial port information contained within @serinfo is
+ *	suitable for this port type.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @ioctl: ``int ()(struct uart_port *port, unsigned int cmd,
+ *		unsigned long arg)``
+ *
+ *	Perform any port specific IOCTLs. IOCTL commands must be defined using
+ *	the standard numbering system found in <asm/ioctl.h>.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *
+ * @poll_init: ``int ()(struct uart_port *port)``
+ *
+ *	Called by kgdb to perform the minimal hardware initialization needed to
+ *	support @poll_put_char() and @poll_get_char(). Unlike @startup(), this
+ *	should not request interrupts.
+ *
+ *	Locking: %tty_mutex and tty_port->mutex taken.
+ *	Interrupts: n/a.
+ *
+ * @poll_put_char: ``void ()(struct uart_port *port, unsigned char ch)``
+ *
+ *	Called by kgdb to write a single character @ch directly to the serial
+ *	@port. It can and should block until there is space in the TX FIFO.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *	This call must not sleep
+ *
+ * @poll_get_char: ``int ()(struct uart_port *port)``
+ *
+ *	Called by kgdb to read a single character directly from the serial
+ *	port. If data is available, it should be returned; otherwise the
+ *	function should return %NO_POLL_CHAR immediately.
+ *
+ *	Locking: none.
+ *	Interrupts: caller dependent.
+ *	This call must not sleep
  */
 struct uart_ops {
 	unsigned int	(*tx_empty)(struct uart_port *);
@@ -56,22 +383,8 @@ struct uart_ops {
 	void		(*set_ldisc)(struct uart_port *, struct ktermios *);
 	void		(*pm)(struct uart_port *, unsigned int state,
 			      unsigned int oldstate);
-
-	/*
-	 * Return a string describing the type of the port
-	 */
 	const char	*(*type)(struct uart_port *);
-
-	/*
-	 * Release IO and memory resources used by the port.
-	 * This includes iounmap if necessary.
-	 */
 	void		(*release_port)(struct uart_port *);
-
-	/*
-	 * Request IO and memory resources used by the port.
-	 * This includes iomapping the port if necessary.
-	 */
 	int		(*request_port)(struct uart_port *);
 	void		(*config_port)(struct uart_port *, int);
 	int		(*verify_port)(struct uart_port *, struct serial_struct *);
-- 
cgit v1.2.3-59-g8ed1b


From c4bd17a6ddf3b92bf9d7939ae251570ace14bb52 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 28 Jul 2022 08:10:52 +0200
Subject: Documentation: serial: dedup kernel-doc for uart functions

Some of the serial (uart_*) functions are documented twice. Once as
kernel-doc along their sources and once in Documentation. So deduplicate
these texts, merge them into kernel-doc in the sources, and link them
using kernel-doc: from the Documentation.

To be properly linked and rendered, tabulators had to be removed from
the comments.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst |  84 +----------------
 drivers/tty/serial/serial_core.c           | 141 +++++++++++++++++------------
 2 files changed, 87 insertions(+), 138 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index cb0ec6db4f1e..ac9620e97f4b 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -69,85 +69,11 @@ uart_ops
 Other functions
 ---------------
 
-uart_update_timeout(port,cflag,baud)
-	Update the frame timing information according to the number of bits,
-	parity, stop bits and baud rate. The FIFO drain timeout is derived
-	from the frame timing information.
-
-	Locking: caller is expected to take port->lock
-
-	Interrupts: n/a
-
-uart_get_baud_rate(port,termios,old,min,max)
-	Return the numeric baud rate for the specified termios, taking
-	account of the special 38400 baud "kludge".  The B0 baud rate
-	is mapped to 9600 baud.
-
-	If the baud rate is not within min..max, then if old is non-NULL,
-	the original baud rate will be tried.  If that exceeds the
-	min..max constraint, 9600 baud will be returned.  termios will
-	be updated to the baud rate in use.
-
-	Note: min..max must always allow 9600 baud to be selected.
-
-	Locking: caller dependent.
-
-	Interrupts: n/a
-
-uart_get_divisor(port,baud)
-	Return the divisor (baud_base / baud) for the specified baud
-	rate, appropriately rounded.
-
-	If 38400 baud and custom divisor is selected, return the
-	custom divisor instead.
-
-	Locking: caller dependent.
-
-	Interrupts: n/a
-
-uart_match_port(port1,port2)
-	This utility function can be used to determine whether two
-	uart_port structures describe the same port.
-
-	Locking: n/a
-
-	Interrupts: n/a
-
-uart_write_wakeup(port)
-	A driver is expected to call this function when the number of
-	characters in the transmit buffer have dropped below a threshold.
-
-	Locking: port->lock should be held.
-
-	Interrupts: n/a
-
-uart_register_driver(drv)
-	Register a uart driver with the core driver.  We in turn register
-	with the tty layer, and initialise the core driver per-port state.
-
-	drv->port should be NULL, and the per-port structures should be
-	registered using uart_add_one_port after this call has succeeded.
-
-	Locking: none
-
-	Interrupts: enabled
-
-uart_unregister_driver()
-	Remove all references to a driver from the core driver.  The low
-	level driver must have removed all its ports via the
-	uart_remove_one_port() if it registered them with uart_add_one_port().
-
-	Locking: none
-
-	Interrupts: enabled
-
-**uart_suspend_port()**
-
-**uart_resume_port()**
-
-**uart_add_one_port()**
-
-**uart_remove_one_port()**
+.. kernel-doc:: drivers/tty/serial/serial_core.c
+   :identifiers: uart_update_timeout uart_get_baud_rate uart_get_divisor
+           uart_match_port uart_write_wakeup uart_register_driver
+           uart_unregister_driver uart_suspend_port uart_resume_port
+           uart_add_one_port uart_remove_one_port
 
 Other notes
 -----------
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index ac198d0d4c80..c302aa34668d 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -97,9 +97,16 @@ static inline struct uart_port *uart_port_check(struct uart_state *state)
 	return state->uart_port;
 }
 
-/*
- * This routine is used by the interrupt handler to schedule processing in
- * the software interrupt portion of the driver.
+/**
+ * uart_write_wakeup - schedule write processing
+ * @port: port to be processed
+ *
+ * This routine is used by the interrupt handler to schedule processing in the
+ * software interrupt portion of the driver. A driver is expected to call this
+ * function when the number of characters in the transmit buffer have dropped
+ * below a threshold.
+ *
+ * Locking: @port->lock should be held
  */
 void uart_write_wakeup(struct uart_port *port)
 {
@@ -327,14 +334,16 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 }
 
 /**
- *	uart_update_timeout - update per-port frame timing information.
- *	@port:  uart_port structure describing the port
- *	@cflag: termios cflag value
- *	@baud:  speed of the port
+ * uart_update_timeout - update per-port frame timing information
+ * @port: uart_port structure describing the port
+ * @cflag: termios cflag value
+ * @baud: speed of the port
  *
- *	Set the port frame timing information from which the FIFO timeout
- *	value is derived. The @cflag value should reflect the actual hardware
- *	settings.
+ * Set the @port frame timing information from which the FIFO timeout value is
+ * derived. The @cflag value should reflect the actual hardware settings as
+ * number of bits, parity, stop bits and baud rate is taken into account here.
+ *
+ * Locking: caller is expected to take @port->lock
  */
 void
 uart_update_timeout(struct uart_port *port, unsigned int cflag,
@@ -349,23 +358,25 @@ uart_update_timeout(struct uart_port *port, unsigned int cflag,
 EXPORT_SYMBOL(uart_update_timeout);
 
 /**
- *	uart_get_baud_rate - return baud rate for a particular port
- *	@port: uart_port structure describing the port in question.
- *	@termios: desired termios settings.
- *	@old: old termios (or NULL)
- *	@min: minimum acceptable baud rate
- *	@max: maximum acceptable baud rate
+ * uart_get_baud_rate - return baud rate for a particular port
+ * @port: uart_port structure describing the port in question.
+ * @termios: desired termios settings
+ * @old: old termios (or %NULL)
+ * @min: minimum acceptable baud rate
+ * @max: maximum acceptable baud rate
+ *
+ * Decode the termios structure into a numeric baud rate, taking account of the
+ * magic 38400 baud rate (with spd_* flags), and mapping the %B0 rate to 9600
+ * baud.
  *
- *	Decode the termios structure into a numeric baud rate,
- *	taking account of the magic 38400 baud rate (with spd_*
- *	flags), and mapping the %B0 rate to 9600 baud.
+ * If the new baud rate is invalid, try the @old termios setting. If it's still
+ * invalid, we try 9600 baud.
  *
- *	If the new baud rate is invalid, try the old termios setting.
- *	If it's still invalid, we try 9600 baud.
+ * The @termios structure is updated to reflect the baud rate we're actually
+ * going to be using. Don't do this for the case where B0 is requested ("hang
+ * up").
  *
- *	Update the @termios structure to reflect the baud rate
- *	we're actually going to be using. Don't do this for the case
- *	where B0 is requested ("hang up").
+ * Locking: caller dependent
  */
 unsigned int
 uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
@@ -450,11 +461,17 @@ uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
 EXPORT_SYMBOL(uart_get_baud_rate);
 
 /**
- *	uart_get_divisor - return uart clock divisor
- *	@port: uart_port structure describing the port.
- *	@baud: desired baud rate
+ * uart_get_divisor - return uart clock divisor
+ * @port: uart_port structure describing the port
+ * @baud: desired baud rate
+ *
+ * Calculate the divisor (baud_base / baud) for the specified @baud,
+ * appropriately rounded.
  *
- *	Calculate the uart clock divisor for the port.
+ * If 38400 baud and custom divisor is selected, return the custom divisor
+ * instead.
+ *
+ * Locking: caller dependent
  */
 unsigned int
 uart_get_divisor(struct uart_port *port, unsigned int baud)
@@ -2683,17 +2700,19 @@ static const struct tty_port_operations uart_port_ops = {
 };
 
 /**
- *	uart_register_driver - register a driver with the uart core layer
- *	@drv: low level driver structure
+ * uart_register_driver - register a driver with the uart core layer
+ * @drv: low level driver structure
+ *
+ * Register a uart driver with the core driver. We in turn register with the
+ * tty layer, and initialise the core driver per-port state.
  *
- *	Register a uart driver with the core driver.  We in turn register
- *	with the tty layer, and initialise the core driver per-port state.
+ * We have a proc file in /proc/tty/driver which is named after the normal
+ * driver.
  *
- *	We have a proc file in /proc/tty/driver which is named after the
- *	normal driver.
+ * @drv->port should be %NULL, and the per-port structures should be registered
+ * using uart_add_one_port() after this call has succeeded.
  *
- *	drv->port should be NULL, and the per-port structures should be
- *	registered using uart_add_one_port after this call has succeeded.
+ * Locking: none, Interrupts: enabled
  */
 int uart_register_driver(struct uart_driver *drv)
 {
@@ -2757,13 +2776,14 @@ out:
 EXPORT_SYMBOL(uart_register_driver);
 
 /**
- *	uart_unregister_driver - remove a driver from the uart core layer
- *	@drv: low level driver structure
+ * uart_unregister_driver - remove a driver from the uart core layer
+ * @drv: low level driver structure
+ *
+ * Remove all references to a driver from the core driver. The low level
+ * driver must have removed all its ports via the uart_remove_one_port() if it
+ * registered them with uart_add_one_port(). (I.e. @drv->port is %NULL.)
  *
- *	Remove all references to a driver from the core driver.  The low
- *	level driver must have removed all its ports via the
- *	uart_remove_one_port() if it registered them with uart_add_one_port().
- *	(ie, drv->port == NULL)
+ * Locking: none, Interrupts: enabled
  */
 void uart_unregister_driver(struct uart_driver *drv)
 {
@@ -3012,16 +3032,15 @@ static const struct attribute_group tty_dev_attr_group = {
 };
 
 /**
- *	uart_add_one_port - attach a driver-defined port structure
- *	@drv: pointer to the uart low level driver structure for this port
- *	@uport: uart port structure to use for this port.
+ * uart_add_one_port - attach a driver-defined port structure
+ * @drv: pointer to the uart low level driver structure for this port
+ * @uport: uart port structure to use for this port.
  *
- *	Context: task context, might sleep
+ * Context: task context, might sleep
  *
- *	This allows the driver to register its own uart_port structure
- *	with the core driver.  The main purpose is to allow the low
- *	level uart drivers to expand uart_port, rather than having yet
- *	more levels of structures.
+ * This allows the driver @drv to register its own uart_port structure with the
+ * core driver. The main purpose is to allow the low level uart drivers to
+ * expand uart_port, rather than having yet more levels of structures.
  */
 int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 {
@@ -3116,15 +3135,14 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 EXPORT_SYMBOL(uart_add_one_port);
 
 /**
- *	uart_remove_one_port - detach a driver defined port structure
- *	@drv: pointer to the uart low level driver structure for this port
- *	@uport: uart port structure for this port
+ * uart_remove_one_port - detach a driver defined port structure
+ * @drv: pointer to the uart low level driver structure for this port
+ * @uport: uart port structure for this port
  *
- *	Context: task context, might sleep
+ * Context: task context, might sleep
  *
- *	This unhooks (and hangs up) the specified port structure from the
- *	core driver.  No further calls will be made to the low-level code
- *	for this port.
+ * This unhooks (and hangs up) the specified port structure from the core
+ * driver. No further calls will be made to the low-level code for this port.
  */
 int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
 {
@@ -3196,8 +3214,13 @@ out:
 }
 EXPORT_SYMBOL(uart_remove_one_port);
 
-/*
- *	Are the two ports equivalent?
+/**
+ * uart_match_port - are the two ports equivalent?
+ * @port1: first port
+ * @port2: second port
+ *
+ * This utility function can be used to determine whether two uart_port
+ * structures describe the same port.
  */
 bool uart_match_port(const struct uart_port *port1,
 		const struct uart_port *port2)
-- 
cgit v1.2.3-59-g8ed1b


From 27940abd555228fdda39a40081ae02450c500f35 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 28 Jul 2022 08:10:53 +0200
Subject: Documentation: serial: move GPIO kernel-doc to the functions

The GPIO uart functions are documented in Documentation. Move and
transform this documentation into kernel-doc directly in the code and
reference it in Documentation using kernel-doc:.

This makes it easier to update, maintain and check by the build.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst | 32 +++-----------------
 drivers/tty/serial/serial_mctrl_gpio.c     | 48 ++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 28 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index ac9620e97f4b..cae280f39189 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -94,31 +94,7 @@ Modem control lines via GPIO
 
 Some helpers are provided in order to set/get modem control lines via GPIO.
 
-mctrl_gpio_init(port, idx):
-	This will get the {cts,rts,...}-gpios from device tree if they are
-	present and request them, set direction etc, and return an
-	allocated structure. `devm_*` functions are used, so there's no need
-	to call mctrl_gpio_free().
-	As this sets up the irq handling make sure to not handle changes to the
-	gpio input lines in your driver, too.
-
-mctrl_gpio_free(dev, gpios):
-	This will free the requested gpios in mctrl_gpio_init().
-	As `devm_*` functions are used, there's generally no need to call
-	this function.
-
-mctrl_gpio_to_gpiod(gpios, gidx)
-	This returns the gpio_desc structure associated to the modem line
-	index.
-
-mctrl_gpio_set(gpios, mctrl):
-	This will sets the gpios according to the mctrl state.
-
-mctrl_gpio_get(gpios, mctrl):
-	This will update mctrl with the gpios values.
-
-mctrl_gpio_enable_ms(gpios):
-	Enables irqs and handling of changes to the ms lines.
-
-mctrl_gpio_disable_ms(gpios):
-	Disables irqs and handling of changes to the ms lines.
+.. kernel-doc:: drivers/tty/serial/serial_mctrl_gpio.c
+   :identifiers: mctrl_gpio_init mctrl_gpio_free mctrl_gpio_to_gpiod
+           mctrl_gpio_set mctrl_gpio_get mctrl_gpio_enable_ms
+           mctrl_gpio_disable_ms
diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index 1663b3afc3a0..7d5aaa8d422b 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -42,6 +42,13 @@ static bool mctrl_gpio_flags_is_dir_out(unsigned int idx)
 	return mctrl_gpios_desc[idx].flags & GPIOD_FLAGS_BIT_DIR_OUT;
 }
 
+/**
+ * mctrl_gpio_set - set gpios according to mctrl state
+ * @gpios: gpios to set
+ * @mctrl: state to set
+ *
+ * Set the gpios according to the mctrl state.
+ */
 void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
 {
 	enum mctrl_gpio_idx i;
@@ -63,6 +70,12 @@ void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 
+/**
+ * mctrl_gpio_to_gpiod - obtain gpio_desc of modem line index
+ * @gpios: gpios to look into
+ * @gidx: index of the modem line
+ * Returns: the gpio_desc structure associated to the modem line index
+ */
 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 				      enum mctrl_gpio_idx gidx)
 {
@@ -73,6 +86,14 @@ struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
 
+/**
+ * mctrl_gpio_get - update mctrl with the gpios values.
+ * @gpios: gpios to get the info from
+ * @mctrl: mctrl to set
+ * Returns: modified mctrl (the same value as in @mctrl)
+ *
+ * Update mctrl with the gpios values.
+ */
 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
 {
 	enum mctrl_gpio_idx i;
@@ -189,6 +210,17 @@ static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
 	return IRQ_HANDLED;
 }
 
+/**
+ * mctrl_gpio_init - initialize uart gpios
+ * @port: port to initialize gpios for
+ * @idx: index of the gpio in the @port's device
+ *
+ * This will get the {cts,rts,...}-gpios from device tree if they are present
+ * and request them, set direction etc, and return an allocated structure.
+ * `devm_*` functions are used, so there's no need to call mctrl_gpio_free().
+ * As this sets up the irq handling, make sure to not handle changes to the
+ * gpio input lines in your driver, too.
+ */
 struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
 {
 	struct mctrl_gpios *gpios;
@@ -235,6 +267,14 @@ struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
 
+/**
+ * mctrl_gpio_free - explicitly free uart gpios
+ * @dev: uart port's device
+ * @gpios: gpios structure to be freed
+ *
+ * This will free the requested gpios in mctrl_gpio_init(). As `devm_*`
+ * functions are used, there's generally no need to call this function.
+ */
 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 {
 	enum mctrl_gpio_idx i;
@@ -253,6 +293,10 @@ void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_free);
 
+/**
+ * mctrl_gpio_enable_ms - enable irqs and handling of changes to the ms lines
+ * @gpios: gpios to enable
+ */
 void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
 {
 	enum mctrl_gpio_idx i;
@@ -278,6 +322,10 @@ void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
 
+/**
+ * mctrl_gpio_disable_ms - disable irqs and handling of changes to the ms lines
+ * @gpios: gpios to disable
+ */
 void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
 {
 	enum mctrl_gpio_idx i;
-- 
cgit v1.2.3-59-g8ed1b


From d34d7c4b774dac1d4be440207ab9e347f599dd30 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 28 Jul 2022 08:10:54 +0200
Subject: Documentation: serial: link uart_ops properly

The syntax to reference a struct in text is "struct XY". So reference
uart_ops properly, so that hyperlinks work.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index cae280f39189..13b580e887b4 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -39,7 +39,7 @@ Locking
 
 It is the responsibility of the low level hardware driver to perform the
 necessary locking using port->lock.  There are some exceptions (which
-are described in the uart_ops listing below.)
+are described in the struct uart_ops listing below.)
 
 There are two locks.  A per-port spinlock, and an overall semaphore.
 
-- 
cgit v1.2.3-59-g8ed1b


From 987233b342b950653d21c5e3e5b78689c995c869 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 28 Jul 2022 08:10:55 +0200
Subject: tty: serial: serial_core, reformat kernel-doc for functions

There are many annotated functions in serial_core.c, but they do not
completely conform to the kernel-doc style. So reformat them and link
them from the Documentation.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst |  11 +--
 drivers/tty/serial/serial_core.c           | 107 ++++++++++++++---------------
 2 files changed, 60 insertions(+), 58 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index 13b580e887b4..e1b440f2c02b 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -25,10 +25,10 @@ Console Support
 ---------------
 
 The serial core provides a few helper functions.  This includes identifing
-the correct port structure (via uart_get_console) and decoding command line
-arguments (uart_parse_options).
+the correct port structure (via uart_get_console()) and decoding command line
+arguments (uart_parse_options()).
 
-There is also a helper function (uart_console_write) which performs a
+There is also a helper function (uart_console_write()) which performs a
 character by character write, translating newlines to CRLF sequences.
 Driver writers are recommended to use this function rather than implementing
 their own version.
@@ -73,7 +73,10 @@ Other functions
    :identifiers: uart_update_timeout uart_get_baud_rate uart_get_divisor
            uart_match_port uart_write_wakeup uart_register_driver
            uart_unregister_driver uart_suspend_port uart_resume_port
-           uart_add_one_port uart_remove_one_port
+           uart_add_one_port uart_remove_one_port uart_console_write
+           uart_parse_earlycon uart_parse_options uart_set_options
+           uart_get_lsr_info uart_handle_dcd_change uart_handle_cts_change
+           uart_try_toggle_sysrq
 
 Other notes
 -----------
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index c302aa34668d..b2943da2d32c 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1034,10 +1034,10 @@ static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
 }
 
 /**
- *	uart_get_lsr_info	-	get line status register info
- *	@tty: tty associated with the UART
- *	@state: UART being queried
- *	@value: returned modem value
+ * uart_get_lsr_info - get line status register info
+ * @tty: tty associated with the UART
+ * @state: UART being queried
+ * @value: returned modem value
  */
 static int uart_get_lsr_info(struct tty_struct *tty,
 			struct uart_state *state, unsigned int __user *value)
@@ -2072,11 +2072,11 @@ static void uart_port_spin_lock_init(struct uart_port *port)
 
 #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
 /**
- *	uart_console_write - write a console message to a serial port
- *	@port: the port to write the message
- *	@s: array of characters
- *	@count: number of characters in string to write
- *	@putchar: function to write character to port
+ * uart_console_write - write a console message to a serial port
+ * @port: the port to write the message
+ * @s: array of characters
+ * @count: number of characters in string to write
+ * @putchar: function to write character to port
  */
 void uart_console_write(struct uart_port *port, const char *s,
 			unsigned int count,
@@ -2115,24 +2115,23 @@ uart_get_console(struct uart_port *ports, int nr, struct console *co)
 }
 
 /**
- *	uart_parse_earlycon - Parse earlycon options
- *	@p:	  ptr to 2nd field (ie., just beyond '<name>,')
- *	@iotype:  ptr for decoded iotype (out)
- *	@addr:    ptr for decoded mapbase/iobase (out)
- *	@options: ptr for <options> field; NULL if not present (out)
+ * uart_parse_earlycon - Parse earlycon options
+ * @p:	     ptr to 2nd field (ie., just beyond '<name>,')
+ * @iotype:  ptr for decoded iotype (out)
+ * @addr:    ptr for decoded mapbase/iobase (out)
+ * @options: ptr for <options> field; %NULL if not present (out)
  *
- *	Decodes earlycon kernel command line parameters of the form
- *	   earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
- *	   console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
+ * Decodes earlycon kernel command line parameters of the form:
+ *  * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
+ *  * console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
  *
- *	The optional form
+ * The optional form:
+ *  * earlycon=<name>,0x<addr>,<options>
+ *  * console=<name>,0x<addr>,<options>
  *
- *	   earlycon=<name>,0x<addr>,<options>
- *	   console=<name>,0x<addr>,<options>
+ * is also accepted; the returned @iotype will be %UPIO_MEM.
  *
- *	is also accepted; the returned @iotype will be UPIO_MEM.
- *
- *	Returns 0 on success or -EINVAL on failure
+ * Returns: 0 on success or -%EINVAL on failure
  */
 int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
 			char **options)
@@ -2177,16 +2176,16 @@ int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
 EXPORT_SYMBOL_GPL(uart_parse_earlycon);
 
 /**
- *	uart_parse_options - Parse serial port baud/parity/bits/flow control.
- *	@options: pointer to option string
- *	@baud: pointer to an 'int' variable for the baud rate.
- *	@parity: pointer to an 'int' variable for the parity.
- *	@bits: pointer to an 'int' variable for the number of data bits.
- *	@flow: pointer to an 'int' variable for the flow control character.
+ * uart_parse_options - Parse serial port baud/parity/bits/flow control.
+ * @options: pointer to option string
+ * @baud: pointer to an 'int' variable for the baud rate.
+ * @parity: pointer to an 'int' variable for the parity.
+ * @bits: pointer to an 'int' variable for the number of data bits.
+ * @flow: pointer to an 'int' variable for the flow control character.
  *
- *	uart_parse_options decodes a string containing the serial console
- *	options.  The format of the string is <baud><parity><bits><flow>,
- *	eg: 115200n8r
+ * uart_parse_options() decodes a string containing the serial console
+ * options. The format of the string is <baud><parity><bits><flow>,
+ * eg: 115200n8r
  */
 void
 uart_parse_options(const char *options, int *baud, int *parity,
@@ -2207,13 +2206,13 @@ uart_parse_options(const char *options, int *baud, int *parity,
 EXPORT_SYMBOL_GPL(uart_parse_options);
 
 /**
- *	uart_set_options - setup the serial console parameters
- *	@port: pointer to the serial ports uart_port structure
- *	@co: console pointer
- *	@baud: baud rate
- *	@parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
- *	@bits: number of data bits
- *	@flow: flow control character - 'r' (rts)
+ * uart_set_options - setup the serial console parameters
+ * @port: pointer to the serial ports uart_port structure
+ * @co: console pointer
+ * @baud: baud rate
+ * @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
+ * @bits: number of data bits
+ * @flow: flow control character - 'r' (rts)
  */
 int
 uart_set_options(struct uart_port *port, struct console *co,
@@ -3248,11 +3247,11 @@ bool uart_match_port(const struct uart_port *port1,
 EXPORT_SYMBOL(uart_match_port);
 
 /**
- *	uart_handle_dcd_change - handle a change of carrier detect state
- *	@uport: uart_port structure for the open port
- *	@status: new carrier detect status, nonzero if active
+ * uart_handle_dcd_change - handle a change of carrier detect state
+ * @uport: uart_port structure for the open port
+ * @status: new carrier detect status, nonzero if active
  *
- *	Caller must hold uport->lock
+ * Caller must hold uport->lock.
  */
 void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
 {
@@ -3283,11 +3282,11 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
 EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
 
 /**
- *	uart_handle_cts_change - handle a change of clear-to-send state
- *	@uport: uart_port structure for the open port
- *	@status: new clear to send status, nonzero if active
+ * uart_handle_cts_change - handle a change of clear-to-send state
+ * @uport: uart_port structure for the open port
+ * @status: new clear to send status, nonzero if active
  *
- *	Caller must hold uport->lock
+ * Caller must hold uport->lock.
  */
 void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
 {
@@ -3358,15 +3357,15 @@ static void uart_sysrq_on(struct work_struct *w)
 static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
 
 /**
- *	uart_try_toggle_sysrq - Enables SysRq from serial line
- *	@port: uart_port structure where char(s) after BREAK met
- *	@ch: new character in the sequence after received BREAK
+ * uart_try_toggle_sysrq - Enables SysRq from serial line
+ * @port: uart_port structure where char(s) after BREAK met
+ * @ch: new character in the sequence after received BREAK
  *
- *	Enables magic SysRq when the required sequence is met on port
- *	(see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
+ * Enables magic SysRq when the required sequence is met on port
+ * (see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
  *
- *	Returns false if @ch is out of enabling sequence and should be
- *	handled some other way, true if @ch was consumed.
+ * Returns: %false if @ch is out of enabling sequence and should be
+ * handled some other way, %true if @ch was consumed.
  */
 bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
 {
-- 
cgit v1.2.3-59-g8ed1b


From 9e5f399f5c9f62e537735f2f8e42bd2f7c255c1f Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 28 Jul 2022 08:10:56 +0200
Subject: tty: serial: document uart_get_console()

This was the only function mentioned in the text, but was neither linked
nor documented. So document and link it, so that hyperlinking works in
the text.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/driver-api/serial/driver.rst |  2 +-
 drivers/tty/serial/serial_core.c           | 13 +++++++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

(limited to 'Documentation/driver-api')

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index e1b440f2c02b..23c6b956cd90 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -76,7 +76,7 @@ Other functions
            uart_add_one_port uart_remove_one_port uart_console_write
            uart_parse_earlycon uart_parse_options uart_set_options
            uart_get_lsr_info uart_handle_dcd_change uart_handle_cts_change
-           uart_try_toggle_sysrq
+           uart_try_toggle_sysrq uart_get_console
 
 Other notes
 -----------
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index b2943da2d32c..339f4c421503 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2092,10 +2092,15 @@ void uart_console_write(struct uart_port *port, const char *s,
 }
 EXPORT_SYMBOL_GPL(uart_console_write);
 
-/*
- *	Check whether an invalid uart number has been specified, and
- *	if so, search for the first available port that does have
- *	console support.
+/**
+ * uart_get_console - get uart port for console
+ * @ports: ports to search in
+ * @nr: number of @ports
+ * @co: console to search for
+ * Returns: uart_port for the console @co
+ *
+ * Check whether an invalid uart number has been specified (as @co->index), and
+ * if so, search for the first available port that does have console support.
  */
 struct uart_port * __init
 uart_get_console(struct uart_port *ports, int nr, struct console *co)
-- 
cgit v1.2.3-59-g8ed1b