diff options
Diffstat (limited to 'include/linux/serial_core.h')
| -rw-r--r-- | include/linux/serial_core.h | 83 |
1 files changed, 65 insertions, 18 deletions
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 21c2e05c1bc3..46647f7ae47a 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -155,6 +155,9 @@ struct uart_port { struct console *cons; /* struct console, if any */ #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(SUPPORT_SYSRQ) unsigned long sysrq; /* sysrq timeout */ +#ifdef CONFIG_MAGIC_SYSRQ_BREAK_EMULATION + char sysrq_emul; /* sysrq break emulation */ +#endif #endif /* flags must be updated while holding port mutex */ @@ -382,24 +385,6 @@ extern void uart_handle_cts_change(struct uart_port *uport, extern void uart_insert_char(struct uart_port *port, unsigned int status, unsigned int overrun, unsigned int ch, unsigned int flag); -#ifdef SUPPORT_SYSRQ -static inline int -uart_handle_sysrq_char(struct uart_port *port, unsigned int ch) -{ - if (port->sysrq) { - if (ch && time_before(jiffies, port->sysrq)) { - handle_sysrq(ch); - port->sysrq = 0; - return 1; - } - port->sysrq = 0; - } - return 0; -} -#else -#define uart_handle_sysrq_char(port,ch) ({ (void)port; 0; }) -#endif - /* * We do the SysRQ and SAK checking like this... */ @@ -424,6 +409,68 @@ static inline int uart_handle_break(struct uart_port *port) return 0; } +#if defined(SUPPORT_SYSRQ) && defined(CONFIG_MAGIC_SYSRQ_BREAK_EMULATION) +/* + * Emulate a break if we are the serial console and receive ^B, ^R, ^K. + */ +static inline int +uart_handle_sysrq_break_emulation(struct uart_port *port, unsigned int ch) +{ + const unsigned int ctrlb = 'B' & 31; + const unsigned int ctrlr = 'R' & 31; + const unsigned int ctrlk = 'K' & 31; + + if (uart_console(port)) { + if ((port->sysrq_emul == 0 && ch == ctrlb) || + (port->sysrq_emul == ctrlb && ch == ctrlr)) { + /* for either of the first two trigger characters + * update the state variable and move on. + */ + port->sysrq_emul = ch; + return 1; + } else if (port->sysrq_emul == ctrlr && + ch == ctrlk && uart_handle_break(port)) { + /* the break has already been emulated whilst + * evaluating the condition, tidy up and move on + */ + port->sysrq_emul = 0; + return 1; + } + } + + if (port->sysrq_emul) { + /* received a partial (false) trigger, tidy up and move on */ + uart_insert_char(port, 0, 0, ctrlb, TTY_NORMAL); + if (port->sysrq_emul == ctrlr) + uart_insert_char(port, 0, 0, ctrlr, TTY_NORMAL); + port->sysrq_emul = 0; + } + + return 0; +} +#else +#define uart_handle_sysrq_break_emulation(port,ch) ({ (void)port; 0; }) +#endif + +#ifdef SUPPORT_SYSRQ +static inline int +uart_handle_sysrq_char(struct uart_port *port, unsigned int ch) +{ + if (port->sysrq) { + if (ch && time_before(jiffies, port->sysrq)) { + handle_sysrq(ch); + port->sysrq = 0; + return 1; + } + port->sysrq = 0; + } + + return uart_handle_sysrq_break_emulation(port, ch); +} +#else +#define uart_handle_sysrq_char(port,ch) ({ (void)port; 0; }) +#endif + /* * UART_ENABLE_MS - determine if port should enable modem status irqs */ |