diff options
Diffstat (limited to 'debian/patches-rt/0047-serial-8250-Switch-to-nbcon-console.patch')
| -rw-r--r-- | debian/patches-rt/0047-serial-8250-Switch-to-nbcon-console.patch | 335 |
1 files changed, 335 insertions, 0 deletions
diff --git a/debian/patches-rt/0047-serial-8250-Switch-to-nbcon-console.patch b/debian/patches-rt/0047-serial-8250-Switch-to-nbcon-console.patch new file mode 100644 index 0000000000..015a996d2c --- /dev/null +++ b/debian/patches-rt/0047-serial-8250-Switch-to-nbcon-console.patch @@ -0,0 +1,335 @@ +From: John Ogness <john.ogness@linutronix.de> +Date: Wed, 13 Sep 2023 15:30:36 +0000 +Subject: [PATCH 47/50] serial: 8250: Switch to nbcon console +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.7/older/patches-6.7-rt6.tar.xz + +Implement the necessary callbacks to switch the 8250 console driver +to perform as an nbcon console. + +Add implementations for the nbcon consoles (write_atomic, write_thread, +driver_enter, driver_exit) and add CON_NBCON to the initial flags. + +The legacy code is kept in order to easily switch back to legacy mode +by defining CONFIG_SERIAL_8250_LEGACY_CONSOLE. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/8250/8250_core.c | 42 +++++++++ + drivers/tty/serial/8250/8250_port.c | 156 +++++++++++++++++++++++++++++++++++- + include/linux/serial_8250.h | 6 + + 3 files changed, 201 insertions(+), 3 deletions(-) + +--- a/drivers/tty/serial/8250/8250_core.c ++++ b/drivers/tty/serial/8250/8250_core.c +@@ -592,6 +592,7 @@ serial8250_register_ports(struct uart_dr + + #ifdef CONFIG_SERIAL_8250_CONSOLE + ++#ifdef CONFIG_SERIAL_8250_LEGACY_CONSOLE + static void univ8250_console_write(struct console *co, const char *s, + unsigned int count) + { +@@ -599,6 +600,37 @@ static void univ8250_console_write(struc + + serial8250_console_write(up, s, count); + } ++#else ++static bool univ8250_console_write_atomic(struct console *co, ++ struct nbcon_write_context *wctxt) ++{ ++ struct uart_8250_port *up = &serial8250_ports[co->index]; ++ ++ return serial8250_console_write_atomic(up, wctxt); ++} ++ ++static bool univ8250_console_write_thread(struct console *co, ++ struct nbcon_write_context *wctxt) ++{ ++ struct uart_8250_port *up = &serial8250_ports[co->index]; ++ ++ return serial8250_console_write_thread(up, wctxt); ++} ++ ++static void univ8250_console_driver_enter(struct console *con, unsigned long *flags) ++{ ++ struct uart_port *up = &serial8250_ports[con->index].port; ++ ++ __uart_port_lock_irqsave(up, flags); ++} ++ ++static void univ8250_console_driver_exit(struct console *con, unsigned long flags) ++{ ++ struct uart_port *up = &serial8250_ports[con->index].port; ++ ++ __uart_port_unlock_irqrestore(up, flags); ++} ++#endif /* CONFIG_SERIAL_8250_LEGACY_CONSOLE */ + + static int univ8250_console_setup(struct console *co, char *options) + { +@@ -698,12 +730,20 @@ static int univ8250_console_match(struct + + static struct console univ8250_console = { + .name = "ttyS", ++#ifdef CONFIG_SERIAL_8250_LEGACY_CONSOLE + .write = univ8250_console_write, ++ .flags = CON_PRINTBUFFER | CON_ANYTIME, ++#else ++ .write_atomic = univ8250_console_write_atomic, ++ .write_thread = univ8250_console_write_thread, ++ .driver_enter = univ8250_console_driver_enter, ++ .driver_exit = univ8250_console_driver_exit, ++ .flags = CON_PRINTBUFFER | CON_ANYTIME | CON_NBCON, ++#endif + .device = uart_console_device, + .setup = univ8250_console_setup, + .exit = univ8250_console_exit, + .match = univ8250_console_match, +- .flags = CON_PRINTBUFFER | CON_ANYTIME, + .index = -1, + .data = &serial8250_reg, + }; +--- a/drivers/tty/serial/8250/8250_port.c ++++ b/drivers/tty/serial/8250/8250_port.c +@@ -550,6 +550,11 @@ static int serial8250_em485_init(struct + if (!p->em485) + return -ENOMEM; + ++#ifndef CONFIG_SERIAL_8250_LEGACY_CONSOLE ++ if (uart_console(&p->port)) ++ dev_warn(p->port.dev, "no atomic printing for rs485 consoles\n"); ++#endif ++ + hrtimer_init(&p->em485->stop_tx_timer, CLOCK_MONOTONIC, + HRTIMER_MODE_REL); + hrtimer_init(&p->em485->start_tx_timer, CLOCK_MONOTONIC, +@@ -702,7 +707,11 @@ static void serial8250_set_sleep(struct + serial8250_rpm_put(p); + } + +-static void serial8250_clear_IER(struct uart_8250_port *up) ++/* ++ * Only to be used by write_atomic() and the legacy write(), which do not ++ * require port lock. ++ */ ++static void __serial8250_clear_IER(struct uart_8250_port *up) + { + if (up->capabilities & UART_CAP_UUE) + serial_out(up, UART_IER, UART_IER_UUE); +@@ -710,6 +719,11 @@ static void serial8250_clear_IER(struct + serial_out(up, UART_IER, 0); + } + ++static inline void serial8250_clear_IER(struct uart_8250_port *up) ++{ ++ __serial8250_clear_IER(up); ++} ++ + #ifdef CONFIG_SERIAL_8250_RSA + /* + * Attempts to turn on the RSA FIFO. Returns zero on failure. +@@ -3320,6 +3334,11 @@ static void serial8250_console_putchar(s + + wait_for_xmitr(up, UART_LSR_THRE); + serial_port_out(port, UART_TX, ch); ++ ++ if (ch == '\n') ++ up->console_newline_needed = false; ++ else ++ up->console_newline_needed = true; + } + + /* +@@ -3348,6 +3367,7 @@ static void serial8250_console_restore(s + serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS); + } + ++#ifdef CONFIG_SERIAL_8250_LEGACY_CONSOLE + /* + * Print a string to the serial port using the device FIFO + * +@@ -3406,7 +3426,7 @@ void serial8250_console_write(struct uar + * First save the IER then disable the interrupts + */ + ier = serial_port_in(port, UART_IER); +- serial8250_clear_IER(up); ++ __serial8250_clear_IER(up); + + /* check scratch reg to see if port powered off during system sleep */ + if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) { +@@ -3472,6 +3492,135 @@ void serial8250_console_write(struct uar + if (locked) + uart_port_unlock_irqrestore(port, flags); + } ++#else ++bool serial8250_console_write_thread(struct uart_8250_port *up, ++ struct nbcon_write_context *wctxt) ++{ ++ struct uart_8250_em485 *em485 = up->em485; ++ struct uart_port *port = &up->port; ++ bool done = false; ++ unsigned int ier; ++ ++ touch_nmi_watchdog(); ++ ++ if (!nbcon_enter_unsafe(wctxt)) ++ return false; ++ ++ /* First save IER then disable the interrupts. */ ++ ier = serial_port_in(port, UART_IER); ++ serial8250_clear_IER(up); ++ ++ /* Check scratch reg if port powered off during system sleep. */ ++ if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) { ++ serial8250_console_restore(up); ++ up->canary = 0; ++ } ++ ++ if (em485) { ++ if (em485->tx_stopped) ++ up->rs485_start_tx(up); ++ mdelay(port->rs485.delay_rts_before_send); ++ } ++ ++ if (nbcon_exit_unsafe(wctxt)) { ++ int len = READ_ONCE(wctxt->len); ++ int i; ++ ++ /* ++ * Write out the message. Toggle unsafe for each byte in order ++ * to give another (higher priority) context the opportunity ++ * for a friendly takeover. If such a takeover occurs, this ++ * context must reacquire ownership in order to perform final ++ * actions (such as re-enabling the interrupts). ++ * ++ * IMPORTANT: wctxt->outbuf and wctxt->len are no longer valid ++ * after a reacquire so writing the message must be ++ * aborted. ++ */ ++ for (i = 0; i < len; i++) { ++ if (!nbcon_enter_unsafe(wctxt)) { ++ nbcon_reacquire(wctxt); ++ break; ++ } ++ ++ uart_console_write(port, wctxt->outbuf + i, 1, serial8250_console_putchar); ++ ++ if (!nbcon_exit_unsafe(wctxt)) { ++ nbcon_reacquire(wctxt); ++ break; ++ } ++ } ++ done = (i == len); ++ } else { ++ nbcon_reacquire(wctxt); ++ } ++ ++ while (!nbcon_enter_unsafe(wctxt)) ++ nbcon_reacquire(wctxt); ++ ++ /* Finally, wait for transmitter to become empty and restore IER. */ ++ wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); ++ if (em485) { ++ mdelay(port->rs485.delay_rts_after_send); ++ if (em485->tx_stopped) ++ up->rs485_stop_tx(up); ++ } ++ serial_port_out(port, UART_IER, ier); ++ ++ /* ++ * The receive handling will happen properly because the receive ready ++ * bit will still be set; it is not cleared on read. However, modem ++ * control will not, we must call it if we have saved something in the ++ * saved flags while processing with interrupts off. ++ */ ++ if (up->msr_saved_flags) ++ serial8250_modem_status(up); ++ ++ /* Success if no handover/takeover and message fully printed. */ ++ return (nbcon_exit_unsafe(wctxt) && done); ++} ++ ++bool serial8250_console_write_atomic(struct uart_8250_port *up, ++ struct nbcon_write_context *wctxt) ++{ ++ struct uart_port *port = &up->port; ++ unsigned int ier; ++ ++ /* Atomic console not supported for rs485 mode. */ ++ if (up->em485) ++ return false; ++ ++ touch_nmi_watchdog(); ++ ++ if (!nbcon_enter_unsafe(wctxt)) ++ return false; ++ ++ /* ++ * First save IER then disable the interrupts. The special variant to ++ * clear IER is used because atomic printing may occur without holding ++ * the port lock. ++ */ ++ ier = serial_port_in(port, UART_IER); ++ __serial8250_clear_IER(up); ++ ++ /* Check scratch reg if port powered off during system sleep. */ ++ if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) { ++ serial8250_console_restore(up); ++ up->canary = 0; ++ } ++ ++ if (up->console_newline_needed) ++ uart_console_write(port, "\n", 1, serial8250_console_putchar); ++ uart_console_write(port, wctxt->outbuf, wctxt->len, serial8250_console_putchar); ++ ++ /* Finally, wait for transmitter to become empty and restore IER. */ ++ wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); ++ serial_port_out(port, UART_IER, ier); ++ ++ /* Success if no handover/takeover. */ ++ return nbcon_exit_unsafe(wctxt); ++} ++#endif /* CONFIG_SERIAL_8250_LEGACY_CONSOLE */ + + static unsigned int probe_baud(struct uart_port *port) + { +@@ -3490,6 +3639,7 @@ static unsigned int probe_baud(struct ua + + int serial8250_console_setup(struct uart_port *port, char *options, bool probe) + { ++ struct uart_8250_port *up = up_to_u8250p(port); + int baud = 9600; + int bits = 8; + int parity = 'n'; +@@ -3499,6 +3649,8 @@ int serial8250_console_setup(struct uart + if (!port->iobase && !port->membase) + return -ENODEV; + ++ up->console_newline_needed = false; ++ + if (options) + uart_parse_options(options, &baud, &parity, &bits, &flow); + else if (probe) +--- a/include/linux/serial_8250.h ++++ b/include/linux/serial_8250.h +@@ -153,6 +153,8 @@ struct uart_8250_port { + #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA + unsigned char msr_saved_flags; + ++ bool console_newline_needed; ++ + struct uart_8250_dma *dma; + const struct uart_8250_ops *ops; + +@@ -204,6 +206,10 @@ void serial8250_init_port(struct uart_82 + void serial8250_set_defaults(struct uart_8250_port *up); + void serial8250_console_write(struct uart_8250_port *up, const char *s, + unsigned int count); ++bool serial8250_console_write_atomic(struct uart_8250_port *up, ++ struct nbcon_write_context *wctxt); ++bool serial8250_console_write_thread(struct uart_8250_port *up, ++ struct nbcon_write_context *wctxt); + int serial8250_console_setup(struct uart_port *port, char *options, bool probe); + int serial8250_console_exit(struct uart_port *port); + |