From 61848e9799f2543a3ea144e277b17aaec9707566 Mon Sep 17 00:00:00 2001 From: Ethan Nelson-Moore Date: Sun, 3 May 2026 20:14:53 -0700 Subject: tty: synclink_gt: remove broken driver The synclink_gt driver was marked as broken in commit 426263d5fb40 ("tty: synclink_gt: mark as BROKEN") in July 2023 because it had severe structural problems and there had been no evidence of users since 2016. Since then, no meaningful improvements have been made to the driver, and it is unlikely that will ever happen due to the lack of interest. Drop the driver and references to it in comments and documentation. include/uapi/linux/synclink.h is also removed. The only use of this header I have found is the linux-raw-sys Rust crate. It generates bindings for all UAPI headers, but has a hardcoded list of headers and ioctls, including this one, so that does not indicate that anyone is using it. I have sent a pull request to remove the include and ioctl definitions for this header (see the link below). Link: https://github.com/sunfishcode/linux-raw-sys/pull/185 Signed-off-by: Ethan Nelson-Moore Acked-by: Jakub Kicinski Link: https://patch.msgid.link/20260504031519.18877-1-enelsonmoore@gmail.com Signed-off-by: Greg Kroah-Hartman --- include/linux/synclink.h | 37 ------------------------------------- 1 file changed, 37 deletions(-) delete mode 100644 include/linux/synclink.h (limited to 'include/linux') diff --git a/include/linux/synclink.h b/include/linux/synclink.h deleted file mode 100644 index f1405b1c71ba..000000000000 --- a/include/linux/synclink.h +++ /dev/null @@ -1,37 +0,0 @@ -/* - * SyncLink Multiprotocol Serial Adapter Driver - * - * $Id: synclink.h,v 3.14 2006/07/17 20:15:43 paulkf Exp $ - * - * Copyright (C) 1998-2000 by Microgate Corporation - * - * Redistribution of this file is permitted under - * the terms of the GNU Public License (GPL) - */ -#ifndef _SYNCLINK_H_ -#define _SYNCLINK_H_ - -#include - -/* provide 32 bit ioctl compatibility on 64 bit systems */ -#ifdef CONFIG_COMPAT -#include -struct MGSL_PARAMS32 { - compat_ulong_t mode; - unsigned char loopback; - unsigned short flags; - unsigned char encoding; - compat_ulong_t clock_speed; - unsigned char addr_filter; - unsigned short crc_type; - unsigned char preamble_length; - unsigned char preamble; - compat_ulong_t data_rate; - unsigned char data_bits; - unsigned char stop_bits; - unsigned char parity; -}; -#define MGSL_IOCSPARAMS32 _IOW(MGSL_MAGIC_IOC,0,struct MGSL_PARAMS32) -#define MGSL_IOCGPARAMS32 _IOR(MGSL_MAGIC_IOC,1,struct MGSL_PARAMS32) -#endif -#endif /* _SYNCLINK_H_ */ -- cgit v1.2.3 From 430a1386df5c98e65f6b943c15366e4ca92e3328 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Wed, 6 May 2026 14:46:43 +0200 Subject: serial: sh-sci: Remove plat_sci_port.flags The last setter of p->flags was removed in commit 37744feebc086908 ("sh: remove sh5 support") in v5.8. Link: https://lore.kernel.org/CAMuHMdXs94k3-7YD-yO7p2=+u8waYGAz8mpP5LDbMf3szt4V-w@mail.gmail.com Signed-off-by: Geert Uytterhoeven Reviewed-by: John Ogness Reviewed-by: Lad Prabhakar Link: https://patch.msgid.link/20260506124643.128021-1-geert+renesas@glider.be Signed-off-by: Greg Kroah-Hartman --- include/linux/serial_sci.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/serial_sci.h b/include/linux/serial_sci.h index 0f2f50b8d28e..36c795d61f7e 100644 --- a/include/linux/serial_sci.h +++ b/include/linux/serial_sci.h @@ -51,7 +51,6 @@ struct plat_sci_port_ops { */ struct plat_sci_port { unsigned int type; /* SCI / SCIF / IRDA / HSCIF */ - upf_t flags; /* UPF_* flags */ unsigned int sampling_rate; unsigned int scscr; /* SCSCR initialization */ -- cgit v1.2.3 From 9c7eb1c9c3e3bfecb556fc8fa1b68939385444de Mon Sep 17 00:00:00 2001 From: John Ogness Date: Wed, 6 May 2026 14:21:56 +0206 Subject: serial: core: Add dedicated uart_port field for console flow Currently the UPF_CONS_FLOW bit in the uart_port.flags field is used by serial console drivers to identify if a user has configured flow control on the console. Usually this policy is setup during early boot, but can be changed at runtime. The bits in uart_port.flags are either hardware and driver properties that are initialized before usage or are properties that can be changed via the tty layer. The UPF_CONS_FLOW bit is an exception because it is a console-only policy that can change at runtime and its setting and usage have nothing to do with the tty layer. This actually causes a problem for its usage because uart_port.flags is synchronized by a related tty_port.mutex, but a console has no relation to a tty (other than sharing the port). This is probably why console flow control is not properly available for most serial drivers. And it is hindering being able to provide a proper implementation. Commit d01f4d181c92 ("serial: core: Privatize tty->hw_stopped") addressed a similar issue to deal with software assisted CTS flow state tracking. Add a new uart_port boolean field "cons_flow" to store the user configuration for console flow control. Add getter/setter wrappers to allow for adding more policies later and/or locking constraint validation. Mark UPF_CONS_FLOW as deprecated. Signed-off-by: John Ogness Link: https://patch.msgid.link/20260506121606.5805-2-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman --- include/linux/serial_core.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux') diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 666430b47899..4f7bbdd90017 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -533,6 +533,7 @@ struct uart_port { #define UPF_HARD_FLOW ((__force upf_t) (UPF_AUTO_CTS | UPF_AUTO_RTS)) /* Port has hardware-assisted s/w flow control */ #define UPF_SOFT_FLOW ((__force upf_t) BIT_ULL(22)) +/* Deprecated: use uart_set_cons_flow_enabled()/uart_cons_flow_enabled() instead. */ #define UPF_CONS_FLOW ((__force upf_t) BIT_ULL(23)) #define UPF_SHARE_IRQ ((__force upf_t) BIT_ULL(24)) #define UPF_EXAR_EFR ((__force upf_t) BIT_ULL(25)) @@ -567,6 +568,7 @@ struct uart_port { #define UPSTAT_SYNC_FIFO ((__force upstat_t) (1 << 5)) bool hw_stopped; /* sw-assisted CTS flow state */ + bool cons_flow; /* user specified console flow control */ unsigned int mctrl; /* current modem ctrl settings */ unsigned int frame_time; /* frame timing in ns */ unsigned int type; /* port type */ @@ -1163,6 +1165,16 @@ static inline bool uart_softcts_mode(struct uart_port *uport) return ((uport->status & mask) == UPSTAT_CTS_ENABLE); } +static inline void uart_set_cons_flow_enabled(struct uart_port *uport, bool enabled) +{ + uport->cons_flow = enabled; +} + +static inline bool uart_cons_flow_enabled(const struct uart_port *uport) +{ + return uport->cons_flow; +} + /* * The following are helper functions for the low level drivers. */ -- cgit v1.2.3 From 5e6dfb87b191f34b1bb7cfb4d668665e5b70687b Mon Sep 17 00:00:00 2001 From: John Ogness Date: Mon, 11 May 2026 17:33:02 +0206 Subject: serial: 8250: Add support for console flow control The kernel documentation specifies that the console option 'r' can be used to enable hardware flow control for console writes. The 8250 driver does include code for hardware flow control on the console if cons_flow is set, but there is no code path that actually sets this. However, that is not the only issue. The problems are: 1. Specifying the console option 'r' does not lead to cons_flow being set. 2. Even if cons_flow would be set, serial8250_register_8250_port() clears it. 3. When the console option 'r' is specified, uart_set_options() attempts to initialize the port for CRTSCTS. However, afterwards it does not set the UPSTAT_CTS_ENABLE status bit and therefore on boot, uart_cts_enabled() is always false. This policy bit is important for console drivers as a criteria if they may poll CTS. 4. Even though uart_set_options() attempts to initialize the port for CRTSCTS, the 8250 set_termios() callback does not enable the RTS signal (TIOCM_RTS) and thus the hardware is not properly initialized for CTS polling. 5. Even if modem control was properly setup for CTS polling (TIOCM_RTS), uart_configure_port() clears TIOCM_RTS, thus breaking CTS polling. 6. wait_for_xmitr() and serial8250_console_write() use cons_flow to decide if CTS polling should occur. However, the condition should also include a check that it is not in RS485 mode and CRTSCTS is actually enabled in the hardware. Address all these issues as conservatively as possible by gating them behind checks focussed on the user specifying console hardware flow control support and the hardware being configured for CTS polling at the time of the write to the UART. Since checking the UPSTAT_CTS_ENABLE status bit is a part of the new condition gate, these changes also support runtime termios updates to disable/enable CRTSCTS. Signed-off-by: John Ogness Link: https://patch.msgid.link/20260511152706.151498-4-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman --- include/linux/serial_core.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux') diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 4f7bbdd90017..17fcff466e30 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -1175,6 +1175,14 @@ static inline bool uart_cons_flow_enabled(const struct uart_port *uport) return uport->cons_flow; } +static inline bool uart_console_hwflow_active(struct uart_port *uport) +{ + return uart_console(uport) && + !(uport->rs485.flags & SER_RS485_ENABLED) && + uart_cons_flow_enabled(uport) && + uart_cts_enabled(uport); +} + /* * The following are helper functions for the low level drivers. */ -- cgit v1.2.3 From 255dc0ec0b79c354bff017f6d6202adaa092a1c9 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Thu, 14 May 2026 23:48:57 -0400 Subject: vt: merge ucs_is_zero_width()/ucs_is_double_width() into ucs_get_width() The hot path in vc_process_ucs() asks two independent questions about the same code point -- "is it double-width?" and "is it zero-width?" -- and was answering each with its own bsearch over its own table. For anything past the leading bounds check that meant two scans of the BMP width tables back to back for what is logically a single lookup. Replace both with one ucs_get_width(cp) returning 0, 1, or 2 in a single bsearch, while keeping the total table footprint at the same 2384 B as before. To do so, merge the zero-width and double-width ranges per region into one sorted-by-`first` table. BMP entries stay 4 bytes; per-entry width is hosted in spare bits of the non-BMP table's `last` field. Non-BMP code points use only 20 of 32 bits, so each u32 has 12 unused high bits. Store first/last shifted left by 12 and use the low 12 bits of `last` for metadata: bit 11 is this entry's own width flag, bits 0..7 host an 8-bit chunk of the BMP double-width bitmap. Because the metadata bits sit strictly below the lowest cp-scale bit, the bsearch comparator remains a plain u32 compare on shifted keys with no masking. In vc_process_ucs() the overwhelmingly common single-width path now collapses to a single predicted branch: if (likely(w == 1)) return 1; Note: scripts/checkpatch.pl complains about "Macros with complex values should be enclosed in parentheses" for the BMP_*WIDTH and RANGE_*WIDTH macros. They are deliberately defined to expand to a comma-separated (first, last) pair so they can populate the two adjacent fields of a struct initializer; wrapping them in parentheses would turn that into a comma-expression and defeat the whole construction. Please ignore. Signed-off-by: Nicolas Pitre Link: https://patch.msgid.link/20260515034857.2514225-1-nico@fluxnic.net Signed-off-by: Greg Kroah-Hartman --- include/linux/consolemap.h | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) (limited to 'include/linux') diff --git a/include/linux/consolemap.h b/include/linux/consolemap.h index 6180b803795c..539d488fdc03 100644 --- a/include/linux/consolemap.h +++ b/include/linux/consolemap.h @@ -28,8 +28,7 @@ int conv_uni_to_pc(struct vc_data *conp, long ucs); u32 conv_8bit_to_uni(unsigned char c); int conv_uni_to_8bit(u32 uni); void console_map_init(void); -bool ucs_is_double_width(uint32_t cp); -bool ucs_is_zero_width(uint32_t cp); +unsigned int ucs_get_width(uint32_t cp); u32 ucs_recompose(u32 base, u32 mark); u32 ucs_get_fallback(u32 cp); #else @@ -62,14 +61,9 @@ static inline int conv_uni_to_8bit(u32 uni) static inline void console_map_init(void) { } -static inline bool ucs_is_double_width(uint32_t cp) +static inline unsigned int ucs_get_width(uint32_t cp) { - return false; -} - -static inline bool ucs_is_zero_width(uint32_t cp) -{ - return false; + return 1; } static inline u32 ucs_recompose(u32 base, u32 mark) -- cgit v1.2.3