diff options
Diffstat (limited to 'debian/patches-rt/0021-serial-8250-implement-write_atomic.patch')
| -rw-r--r-- | debian/patches-rt/0021-serial-8250-implement-write_atomic.patch | 938 |
1 files changed, 938 insertions, 0 deletions
diff --git a/debian/patches-rt/0021-serial-8250-implement-write_atomic.patch b/debian/patches-rt/0021-serial-8250-implement-write_atomic.patch new file mode 100644 index 000000000..6a5f5abe2 --- /dev/null +++ b/debian/patches-rt/0021-serial-8250-implement-write_atomic.patch @@ -0,0 +1,938 @@ +From 08b8c0b589806331dc645a8ead6be51c174d93e0 Mon Sep 17 00:00:00 2001 +From: John Ogness <john.ogness@linutronix.de> +Date: Fri, 4 Feb 2022 16:01:17 +0106 +Subject: [PATCH 21/62] serial: 8250: implement write_atomic +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz + +Implement a non-sleeping NMI-safe write_atomic() console function in +order to support atomic console printing during a panic. + +Trasmitting data requires disabling interrupts. Since write_atomic() +can be called from any context, it may be called while another CPU +is executing in console code. In order to maintain the correct state +of the IER register, use the global cpu_sync to synchronize all +access to the IER register. This synchronization is only necessary +for serial ports that are being used as consoles. + +The global cpu_sync is also used to synchronize between the write() +and write_atomic() callbacks. write() synchronizes per character, +write_atomic() synchronizes per line. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/8250/8250.h | 41 ++++- + drivers/tty/serial/8250/8250_aspeed_vuart.c | 2 +- + drivers/tty/serial/8250/8250_bcm7271.c | 21 ++- + drivers/tty/serial/8250/8250_core.c | 24 ++- + drivers/tty/serial/8250/8250_exar.c | 4 +- + drivers/tty/serial/8250/8250_fsl.c | 3 +- + drivers/tty/serial/8250/8250_ingenic.c | 3 +- + drivers/tty/serial/8250/8250_mtk.c | 32 +++- + drivers/tty/serial/8250/8250_omap.c | 18 +-- + drivers/tty/serial/8250/8250_port.c | 158 ++++++++++++++++---- + drivers/tty/serial/8250/Kconfig | 1 + + include/linux/serial_8250.h | 5 + + 12 files changed, 261 insertions(+), 51 deletions(-) + +diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h +index eeb7b43ebe53..b17715d340c3 100644 +--- a/drivers/tty/serial/8250/8250.h ++++ b/drivers/tty/serial/8250/8250.h +@@ -176,12 +176,49 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value) + up->dl_write(up, value); + } + ++static inline int serial8250_in_IER(struct uart_8250_port *up) ++{ ++ struct uart_port *port = &up->port; ++ unsigned long flags; ++ bool is_console; ++ int ier; ++ ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(flags); ++ ++ ier = serial_in(up, UART_IER); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(flags); ++ ++ return ier; ++} ++ ++static inline void serial8250_set_IER(struct uart_8250_port *up, int ier) ++{ ++ struct uart_port *port = &up->port; ++ unsigned long flags; ++ bool is_console; ++ ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(flags); ++ ++ serial_out(up, UART_IER, ier); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(flags); ++} ++ + static inline bool serial8250_set_THRI(struct uart_8250_port *up) + { + if (up->ier & UART_IER_THRI) + return false; + up->ier |= UART_IER_THRI; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + return true; + } + +@@ -190,7 +227,7 @@ static inline bool serial8250_clear_THRI(struct uart_8250_port *up) + if (!(up->ier & UART_IER_THRI)) + return false; + up->ier &= ~UART_IER_THRI; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + return true; + } + +diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c +index 9d2a7856784f..7cc6b527c088 100644 +--- a/drivers/tty/serial/8250/8250_aspeed_vuart.c ++++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c +@@ -278,7 +278,7 @@ static void __aspeed_vuart_set_throttle(struct uart_8250_port *up, + up->ier &= ~irqs; + if (!throttle) + up->ier |= irqs; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + } + static void aspeed_vuart_set_throttle(struct uart_port *port, bool throttle) + { +diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c +index ffc7f67e27e3..8b211e668bc0 100644 +--- a/drivers/tty/serial/8250/8250_bcm7271.c ++++ b/drivers/tty/serial/8250/8250_bcm7271.c +@@ -609,7 +609,7 @@ static int brcmuart_startup(struct uart_port *port) + * will handle this. + */ + up->ier &= ~UART_IER_RDI; +- serial_port_out(port, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + + priv->tx_running = false; + priv->dma.rx_dma = NULL; +@@ -775,10 +775,12 @@ static int brcmuart_handle_irq(struct uart_port *p) + unsigned int iir = serial_port_in(p, UART_IIR); + struct brcmuart_priv *priv = p->private_data; + struct uart_8250_port *up = up_to_u8250p(p); ++ unsigned long cs_flags; + unsigned int status; + unsigned long flags; + unsigned int ier; + unsigned int mcr; ++ bool is_console; + int handled = 0; + + /* +@@ -789,6 +791,10 @@ static int brcmuart_handle_irq(struct uart_port *p) + spin_lock_irqsave(&p->lock, flags); + status = serial_port_in(p, UART_LSR); + if ((status & UART_LSR_DR) == 0) { ++ is_console = uart_console(p); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(cs_flags); + + ier = serial_port_in(p, UART_IER); + /* +@@ -809,6 +815,9 @@ static int brcmuart_handle_irq(struct uart_port *p) + serial_port_in(p, UART_RX); + } + ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(cs_flags); ++ + handled = 1; + } + spin_unlock_irqrestore(&p->lock, flags); +@@ -823,8 +832,10 @@ static enum hrtimer_restart brcmuart_hrtimer_func(struct hrtimer *t) + struct brcmuart_priv *priv = container_of(t, struct brcmuart_priv, hrt); + struct uart_port *p = priv->up; + struct uart_8250_port *up = up_to_u8250p(p); ++ unsigned long cs_flags; + unsigned int status; + unsigned long flags; ++ bool is_console; + + if (priv->shutdown) + return HRTIMER_NORESTART; +@@ -846,12 +857,20 @@ static enum hrtimer_restart brcmuart_hrtimer_func(struct hrtimer *t) + /* re-enable receive unless upper layer has disabled it */ + if ((up->ier & (UART_IER_RLSI | UART_IER_RDI)) == + (UART_IER_RLSI | UART_IER_RDI)) { ++ is_console = uart_console(p); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(cs_flags); ++ + status = serial_port_in(p, UART_IER); + status |= (UART_IER_RLSI | UART_IER_RDI); + serial_port_out(p, UART_IER, status); + status = serial_port_in(p, UART_MCR); + status |= UART_MCR_RTS; + serial_port_out(p, UART_MCR, status); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(cs_flags); + } + spin_unlock_irqrestore(&p->lock, flags); + return HRTIMER_NORESTART; +diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c +index 81a5dab1a828..536f639ff56c 100644 +--- a/drivers/tty/serial/8250/8250_core.c ++++ b/drivers/tty/serial/8250/8250_core.c +@@ -255,8 +255,11 @@ static void serial8250_timeout(struct timer_list *t) + static void serial8250_backup_timeout(struct timer_list *t) + { + struct uart_8250_port *up = from_timer(up, t, timer); ++ struct uart_port *port = &up->port; + unsigned int iir, ier = 0, lsr; ++ unsigned long cs_flags; + unsigned long flags; ++ bool is_console; + + spin_lock_irqsave(&up->port.lock, flags); + +@@ -265,8 +268,16 @@ static void serial8250_backup_timeout(struct timer_list *t) + * based handler. + */ + if (up->port.irq) { ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(cs_flags); ++ + ier = serial_in(up, UART_IER); + serial_out(up, UART_IER, 0); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(cs_flags); + } + + iir = serial_in(up, UART_IIR); +@@ -289,7 +300,7 @@ static void serial8250_backup_timeout(struct timer_list *t) + serial8250_tx_chars(up); + + if (up->port.irq) +- serial_out(up, UART_IER, ier); ++ serial8250_set_IER(up, ier); + + spin_unlock_irqrestore(&up->port.lock, flags); + +@@ -575,6 +586,14 @@ serial8250_register_ports(struct uart_driver *drv, struct device *dev) + + #ifdef CONFIG_SERIAL_8250_CONSOLE + ++static void univ8250_console_write_atomic(struct console *co, const char *s, ++ unsigned int count) ++{ ++ struct uart_8250_port *up = &serial8250_ports[co->index]; ++ ++ serial8250_console_write_atomic(up, s, count); ++} ++ + static void univ8250_console_write(struct console *co, const char *s, + unsigned int count) + { +@@ -668,6 +687,7 @@ static int univ8250_console_match(struct console *co, char *name, int idx, + + static struct console univ8250_console = { + .name = "ttyS", ++ .write_atomic = univ8250_console_write_atomic, + .write = univ8250_console_write, + .device = uart_console_device, + .setup = univ8250_console_setup, +@@ -961,7 +981,7 @@ static void serial_8250_overrun_backoff_work(struct work_struct *work) + spin_lock_irqsave(&port->lock, flags); + up->ier |= UART_IER_RLSI | UART_IER_RDI; + up->port.read_status_mask |= UART_LSR_DR; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + spin_unlock_irqrestore(&port->lock, flags); + } + +diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c +index b406cba10b0e..246c32c75a4c 100644 +--- a/drivers/tty/serial/8250/8250_exar.c ++++ b/drivers/tty/serial/8250/8250_exar.c +@@ -189,6 +189,8 @@ static void xr17v35x_set_divisor(struct uart_port *p, unsigned int baud, + + static int xr17v35x_startup(struct uart_port *port) + { ++ struct uart_8250_port *up = up_to_u8250p(port); ++ + /* + * First enable access to IER [7:5], ISR [5:4], FCR [5:4], + * MCR [7:5] and MSR [7:0] +@@ -199,7 +201,7 @@ static int xr17v35x_startup(struct uart_port *port) + * Make sure all interrups are masked until initialization is + * complete and the FIFOs are cleared + */ +- serial_port_out(port, UART_IER, 0); ++ serial8250_set_IER(up, 0); + + return serial8250_do_startup(port); + } +diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c +index 8adfaa183f77..eaf148245a10 100644 +--- a/drivers/tty/serial/8250/8250_fsl.c ++++ b/drivers/tty/serial/8250/8250_fsl.c +@@ -58,7 +58,8 @@ int fsl8250_handle_irq(struct uart_port *port) + if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) { + unsigned long delay; + +- up->ier = port->serial_in(port, UART_IER); ++ up->ier = serial8250_in_IER(up); ++ + if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { + port->ops->stop_rx(port); + } else { +diff --git a/drivers/tty/serial/8250/8250_ingenic.c b/drivers/tty/serial/8250/8250_ingenic.c +index 2b2f5d8d24b9..2b78e6c394fb 100644 +--- a/drivers/tty/serial/8250/8250_ingenic.c ++++ b/drivers/tty/serial/8250/8250_ingenic.c +@@ -146,6 +146,7 @@ OF_EARLYCON_DECLARE(x1000_uart, "ingenic,x1000-uart", + + static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value) + { ++ struct uart_8250_port *up = up_to_u8250p(p); + int ier; + + switch (offset) { +@@ -167,7 +168,7 @@ static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value) + * If we have enabled modem status IRQs we should enable + * modem mode. + */ +- ier = p->serial_in(p, UART_IER); ++ ier = serial8250_in_IER(up); + + if (ier & UART_IER_MSI) + value |= UART_MCR_MDCE | UART_MCR_FCM; +diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c +index fb1d5ec0940e..3e7203909d6a 100644 +--- a/drivers/tty/serial/8250/8250_mtk.c ++++ b/drivers/tty/serial/8250/8250_mtk.c +@@ -222,12 +222,40 @@ static void mtk8250_shutdown(struct uart_port *port) + + static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask) + { +- serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask)); ++ struct uart_port *port = &up->port; ++ unsigned long flags; ++ bool is_console; ++ int ier; ++ ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(flags); ++ ++ ier = serial_in(up, UART_IER); ++ serial_out(up, UART_IER, ier & (~mask)); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(flags); + } + + static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask) + { +- serial_out(up, UART_IER, serial_in(up, UART_IER) | mask); ++ struct uart_port *port = &up->port; ++ unsigned long flags; ++ bool is_console; ++ int ier; ++ ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(flags); ++ ++ ier = serial_in(up, UART_IER); ++ serial_out(up, UART_IER, ier | mask); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(flags); + } + + static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode) +diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c +index 0b04d810b3e6..2b8ad5176399 100644 +--- a/drivers/tty/serial/8250/8250_omap.c ++++ b/drivers/tty/serial/8250/8250_omap.c +@@ -330,7 +330,7 @@ static void omap8250_restore_regs(struct uart_8250_port *up) + /* drop TCR + TLR access, we setup XON/XOFF later */ + serial8250_out_MCR(up, mcr); + +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + + serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); + serial_dl_write(up, priv->quot); +@@ -520,7 +520,7 @@ static void omap_8250_pm(struct uart_port *port, unsigned int state, + serial_out(up, UART_EFR, efr | UART_EFR_ECB); + serial_out(up, UART_LCR, 0); + +- serial_out(up, UART_IER, (state != 0) ? UART_IERX_SLEEP : 0); ++ serial8250_set_IER(up, (state != 0) ? UART_IERX_SLEEP : 0); + serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); + serial_out(up, UART_EFR, efr); + serial_out(up, UART_LCR, 0); +@@ -703,7 +703,7 @@ static int omap_8250_startup(struct uart_port *port) + goto err; + + up->ier = UART_IER_RLSI | UART_IER_RDI; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + + #ifdef CONFIG_PM + up->capabilities |= UART_CAP_RPM; +@@ -744,7 +744,7 @@ static void omap_8250_shutdown(struct uart_port *port) + serial_out(up, UART_OMAP_EFR2, 0x0); + + up->ier = 0; +- serial_out(up, UART_IER, 0); ++ serial8250_set_IER(up, 0); + + if (up->dma) + serial8250_release_dma(up); +@@ -792,7 +792,7 @@ static void omap_8250_unthrottle(struct uart_port *port) + up->dma->rx_dma(up); + up->ier |= UART_IER_RLSI | UART_IER_RDI; + port->read_status_mask |= UART_LSR_DR; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + spin_unlock_irqrestore(&port->lock, flags); + + pm_runtime_mark_last_busy(port->dev); +@@ -883,7 +883,7 @@ static void __dma_rx_complete(void *param) + __dma_rx_do_complete(p); + if (!priv->throttled) { + p->ier |= UART_IER_RLSI | UART_IER_RDI; +- serial_out(p, UART_IER, p->ier); ++ serial8250_set_IER(p, p->ier); + if (!(priv->habit & UART_HAS_EFR2)) + omap_8250_rx_dma(p); + } +@@ -940,7 +940,7 @@ static int omap_8250_rx_dma(struct uart_8250_port *p) + * callback to run. + */ + p->ier &= ~(UART_IER_RLSI | UART_IER_RDI); +- serial_out(p, UART_IER, p->ier); ++ serial8250_set_IER(p, p->ier); + } + goto out; + } +@@ -1153,12 +1153,12 @@ static void am654_8250_handle_rx_dma(struct uart_8250_port *up, u8 iir, + * periodic timeouts, re-enable interrupts. + */ + up->ier &= ~(UART_IER_RLSI | UART_IER_RDI); +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + omap_8250_rx_dma_flush(up); + serial_in(up, UART_IIR); + serial_out(up, UART_OMAP_EFR2, 0x0); + up->ier |= UART_IER_RLSI | UART_IER_RDI; +- serial_out(up, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + } + } + +diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c +index 8efe31448df3..975c16267196 100644 +--- a/drivers/tty/serial/8250/8250_port.c ++++ b/drivers/tty/serial/8250/8250_port.c +@@ -744,7 +744,7 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) + serial_out(p, UART_EFR, UART_EFR_ECB); + serial_out(p, UART_LCR, 0); + } +- serial_out(p, UART_IER, sleep ? UART_IERX_SLEEP : 0); ++ serial8250_set_IER(p, sleep ? UART_IERX_SLEEP : 0); + if (p->capabilities & UART_CAP_EFR) { + serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B); + serial_out(p, UART_EFR, efr); +@@ -755,12 +755,29 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) + serial8250_rpm_put(p); + } + +-static void serial8250_clear_IER(struct uart_8250_port *up) ++static unsigned int serial8250_clear_IER(struct uart_8250_port *up) + { ++ struct uart_port *port = &up->port; ++ unsigned int clearval = 0; ++ unsigned long flags; ++ bool is_console; ++ unsigned int prior; ++ ++ is_console = uart_console(port); ++ + if (up->capabilities & UART_CAP_UUE) +- serial_out(up, UART_IER, UART_IER_UUE); +- else +- serial_out(up, UART_IER, 0); ++ clearval = UART_IER_UUE; ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(flags); ++ ++ prior = serial_in(up, UART_IER); ++ serial_out(up, UART_IER, clearval); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(flags); ++ ++ return prior; + } + + #ifdef CONFIG_SERIAL_8250_RSA +@@ -1026,8 +1043,11 @@ static int broken_efr(struct uart_8250_port *up) + */ + static void autoconfig_16550a(struct uart_8250_port *up) + { ++ struct uart_port *port = &up->port; + unsigned char status1, status2; + unsigned int iersave; ++ unsigned long flags; ++ bool is_console; + + up->port.type = PORT_16550A; + up->capabilities |= UART_CAP_FIFO; +@@ -1139,6 +1159,11 @@ static void autoconfig_16550a(struct uart_8250_port *up) + return; + } + ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(flags); ++ + /* + * Try writing and reading the UART_IER_UUE bit (b6). + * If it works, this is probably one of the Xscale platform's +@@ -1174,6 +1199,9 @@ static void autoconfig_16550a(struct uart_8250_port *up) + } + serial_out(up, UART_IER, iersave); + ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(flags); ++ + /* + * We distinguish between 16550A and U6 16550A by counting + * how many bytes are in the FIFO. +@@ -1196,8 +1224,10 @@ static void autoconfig(struct uart_8250_port *up) + unsigned char status1, scratch, scratch2, scratch3; + unsigned char save_lcr, save_mcr; + struct uart_port *port = &up->port; ++ unsigned long cs_flags; + unsigned long flags; + unsigned int old_capabilities; ++ bool is_console; + + if (!port->iobase && !port->mapbase && !port->membase) + return; +@@ -1215,6 +1245,11 @@ static void autoconfig(struct uart_8250_port *up) + up->bugs = 0; + + if (!(port->flags & UPF_BUGGY_UART)) { ++ is_console = uart_console(port); ++ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(cs_flags); ++ + /* + * Do a simple existence test first; if we fail this, + * there's no point trying anything else. +@@ -1244,6 +1279,10 @@ static void autoconfig(struct uart_8250_port *up) + #endif + scratch3 = serial_in(up, UART_IER) & 0x0f; + serial_out(up, UART_IER, scratch); ++ ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(cs_flags); ++ + if (scratch2 != 0 || scratch3 != 0x0F) { + /* + * We failed; there's nothing here +@@ -1367,7 +1406,9 @@ static void autoconfig_irq(struct uart_8250_port *up) + unsigned char save_mcr, save_ier; + unsigned char save_ICP = 0; + unsigned int ICP = 0; ++ unsigned long flags; + unsigned long irqs; ++ bool is_console; + int irq; + + if (port->flags & UPF_FOURPORT) { +@@ -1377,8 +1418,12 @@ static void autoconfig_irq(struct uart_8250_port *up) + inb_p(ICP); + } + +- if (uart_console(port)) ++ is_console = uart_console(port); ++ ++ if (is_console) { + console_lock(); ++ printk_cpu_sync_get_irqsave(flags); ++ } + + /* forget possible initially masked and pending IRQ */ + probe_irq_off(probe_irq_on()); +@@ -1410,8 +1455,10 @@ static void autoconfig_irq(struct uart_8250_port *up) + if (port->flags & UPF_FOURPORT) + outb_p(save_ICP, ICP); + +- if (uart_console(port)) ++ if (is_console) { ++ printk_cpu_sync_put_irqrestore(flags); + console_unlock(); ++ } + + port->irq = (irq > 0) ? irq : 0; + } +@@ -1424,7 +1471,7 @@ static void serial8250_stop_rx(struct uart_port *port) + + up->ier &= ~(UART_IER_RLSI | UART_IER_RDI); + up->port.read_status_mask &= ~UART_LSR_DR; +- serial_port_out(port, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + + serial8250_rpm_put(up); + } +@@ -1454,7 +1501,7 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p) + serial8250_clear_and_reinit_fifos(p); + + p->ier |= UART_IER_RLSI | UART_IER_RDI; +- serial_port_out(&p->port, UART_IER, p->ier); ++ serial8250_set_IER(p, p->ier); + } + } + EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx); +@@ -1703,7 +1750,7 @@ static void serial8250_disable_ms(struct uart_port *port) + mctrl_gpio_disable_ms(up->gpios); + + up->ier &= ~UART_IER_MSI; +- serial_port_out(port, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + } + + static void serial8250_enable_ms(struct uart_port *port) +@@ -1719,7 +1766,7 @@ static void serial8250_enable_ms(struct uart_port *port) + up->ier |= UART_IER_MSI; + + serial8250_rpm_get(up); +- serial_port_out(port, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + serial8250_rpm_put(up); + } + +@@ -2174,8 +2221,7 @@ static void serial8250_put_poll_char(struct uart_port *port, + /* + * First save the IER then disable the interrupts + */ +- ier = serial_port_in(port, UART_IER); +- serial8250_clear_IER(up); ++ ier = serial8250_clear_IER(up); + + wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); + /* +@@ -2188,7 +2234,7 @@ static void serial8250_put_poll_char(struct uart_port *port, + * and restore the IER + */ + wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); +- serial_port_out(port, UART_IER, ier); ++ serial8250_set_IER(up, ier); + serial8250_rpm_put(up); + } + +@@ -2197,8 +2243,10 @@ static void serial8250_put_poll_char(struct uart_port *port, + int serial8250_do_startup(struct uart_port *port) + { + struct uart_8250_port *up = up_to_u8250p(port); ++ unsigned long cs_flags; + unsigned long flags; + unsigned char iir; ++ bool is_console; + int retval; + u16 lsr; + +@@ -2219,7 +2267,7 @@ int serial8250_do_startup(struct uart_port *port) + up->acr = 0; + serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B); + serial_port_out(port, UART_EFR, UART_EFR_ECB); +- serial_port_out(port, UART_IER, 0); ++ serial8250_set_IER(up, 0); + serial_port_out(port, UART_LCR, 0); + serial_icr_write(up, UART_CSR, 0); /* Reset the UART */ + serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B); +@@ -2229,7 +2277,7 @@ int serial8250_do_startup(struct uart_port *port) + + if (port->type == PORT_DA830) { + /* Reset the port */ +- serial_port_out(port, UART_IER, 0); ++ serial8250_set_IER(up, 0); + serial_port_out(port, UART_DA830_PWREMU_MGMT, 0); + mdelay(10); + +@@ -2328,6 +2376,8 @@ int serial8250_do_startup(struct uart_port *port) + if (retval) + goto out; + ++ is_console = uart_console(port); ++ + if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { + unsigned char iir1; + +@@ -2344,6 +2394,9 @@ int serial8250_do_startup(struct uart_port *port) + */ + spin_lock_irqsave(&port->lock, flags); + ++ if (is_console) ++ printk_cpu_sync_get_irqsave(cs_flags); ++ + wait_for_xmitr(up, UART_LSR_THRE); + serial_port_out_sync(port, UART_IER, UART_IER_THRI); + udelay(1); /* allow THRE to set */ +@@ -2354,6 +2407,9 @@ int serial8250_do_startup(struct uart_port *port) + iir = serial_port_in(port, UART_IIR); + serial_port_out(port, UART_IER, 0); + ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(cs_flags); ++ + spin_unlock_irqrestore(&port->lock, flags); + + if (port->irqflags & IRQF_SHARED) +@@ -2408,10 +2464,14 @@ int serial8250_do_startup(struct uart_port *port) + * Do a quick test to see if we receive an interrupt when we enable + * the TX irq. + */ ++ if (is_console) ++ printk_cpu_sync_get_irqsave(cs_flags); + serial_port_out(port, UART_IER, UART_IER_THRI); + lsr = serial_port_in(port, UART_LSR); + iir = serial_port_in(port, UART_IIR); + serial_port_out(port, UART_IER, 0); ++ if (is_console) ++ printk_cpu_sync_put_irqrestore(cs_flags); + + if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) { + if (!(up->bugs & UART_BUG_TXEN)) { +@@ -2443,7 +2503,7 @@ int serial8250_do_startup(struct uart_port *port) + if (up->dma) { + const char *msg = NULL; + +- if (uart_console(port)) ++ if (is_console) + msg = "forbid DMA for kernel console"; + else if (serial8250_request_dma(up)) + msg = "failed to request DMA"; +@@ -2494,7 +2554,7 @@ void serial8250_do_shutdown(struct uart_port *port) + */ + spin_lock_irqsave(&port->lock, flags); + up->ier = 0; +- serial_port_out(port, UART_IER, 0); ++ serial8250_set_IER(up, 0); + spin_unlock_irqrestore(&port->lock, flags); + + synchronize_irq(port->irq); +@@ -2856,7 +2916,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, + if (up->capabilities & UART_CAP_RTOIE) + up->ier |= UART_IER_RTOIE; + +- serial_port_out(port, UART_IER, up->ier); ++ serial8250_set_IER(up, up->ier); + + if (up->capabilities & UART_CAP_EFR) { + unsigned char efr = 0; +@@ -3321,7 +3381,7 @@ EXPORT_SYMBOL_GPL(serial8250_set_defaults); + + #ifdef CONFIG_SERIAL_8250_CONSOLE + +-static void serial8250_console_putchar(struct uart_port *port, unsigned char ch) ++static void serial8250_console_putchar_locked(struct uart_port *port, unsigned char ch) + { + struct uart_8250_port *up = up_to_u8250p(port); + +@@ -3329,6 +3389,18 @@ static void serial8250_console_putchar(struct uart_port *port, unsigned char ch) + serial_port_out(port, UART_TX, ch); + } + ++static void serial8250_console_putchar(struct uart_port *port, unsigned char ch) ++{ ++ struct uart_8250_port *up = up_to_u8250p(port); ++ unsigned long flags; ++ ++ wait_for_xmitr(up, UART_LSR_THRE); ++ ++ printk_cpu_sync_get_irqsave(flags); ++ serial8250_console_putchar_locked(port, ch); ++ printk_cpu_sync_put_irqrestore(flags); ++} ++ + /* + * Restore serial console when h/w power-off detected + */ +@@ -3355,6 +3427,32 @@ static void serial8250_console_restore(struct uart_8250_port *up) + serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS); + } + ++void serial8250_console_write_atomic(struct uart_8250_port *up, ++ const char *s, unsigned int count) ++{ ++ struct uart_port *port = &up->port; ++ unsigned long flags; ++ unsigned int ier; ++ ++ printk_cpu_sync_get_irqsave(flags); ++ ++ touch_nmi_watchdog(); ++ ++ ier = serial8250_clear_IER(up); ++ ++ if (atomic_fetch_inc(&up->console_printing)) { ++ uart_console_write(port, "\n", 1, ++ serial8250_console_putchar_locked); ++ } ++ uart_console_write(port, s, count, serial8250_console_putchar_locked); ++ atomic_dec(&up->console_printing); ++ ++ wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); ++ serial8250_set_IER(up, ier); ++ ++ printk_cpu_sync_put_irqrestore(flags); ++} ++ + /* + * Print a string to the serial port using the device FIFO + * +@@ -3400,20 +3498,15 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, + struct uart_port *port = &up->port; + unsigned long flags; + unsigned int ier, use_fifo; +- int locked = 1; + + touch_nmi_watchdog(); + +- if (oops_in_progress) +- locked = spin_trylock_irqsave(&port->lock, flags); +- else +- spin_lock_irqsave(&port->lock, flags); ++ spin_lock_irqsave(&port->lock, flags); + + /* + * First save the IER then disable the interrupts + */ +- ier = serial_port_in(port, UART_IER); +- serial8250_clear_IER(up); ++ ier = 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))) { +@@ -3447,10 +3540,12 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, + */ + !(up->port.flags & UPF_CONS_FLOW); + ++ atomic_inc(&up->console_printing); + if (likely(use_fifo)) + serial8250_console_fifo_write(up, s, count); + else + uart_console_write(port, s, count, serial8250_console_putchar); ++ atomic_dec(&up->console_printing); + + /* + * Finally, wait for transmitter to become empty +@@ -3463,8 +3558,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, + if (em485->tx_stopped) + up->rs485_stop_tx(up); + } +- +- serial_port_out(port, UART_IER, ier); ++ serial8250_set_IER(up, ier); + + /* + * The receive handling will happen properly because the +@@ -3476,8 +3570,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, + if (up->msr_saved_flags) + serial8250_modem_status(up); + +- if (locked) +- spin_unlock_irqrestore(&port->lock, flags); ++ spin_unlock_irqrestore(&port->lock, flags); + } + + static unsigned int probe_baud(struct uart_port *port) +@@ -3497,6 +3590,7 @@ static unsigned int probe_baud(struct uart_port *port) + + 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'; +@@ -3506,6 +3600,8 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe) + if (!port->iobase && !port->membase) + return -ENODEV; + ++ atomic_set(&up->console_printing, 0); ++ + if (options) + uart_parse_options(options, &baud, &parity, &bits, &flow); + else if (probe) +diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig +index 583a340f9934..1f31320820a6 100644 +--- a/drivers/tty/serial/8250/Kconfig ++++ b/drivers/tty/serial/8250/Kconfig +@@ -9,6 +9,7 @@ config SERIAL_8250 + depends on !S390 + select SERIAL_CORE + select SERIAL_MCTRL_GPIO if GPIOLIB ++ select HAVE_ATOMIC_CONSOLE + help + This selects whether you want to include the driver for the standard + serial ports. The standard answer is Y. People who might say N +diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h +index 79b328861c5f..35f44352e641 100644 +--- a/include/linux/serial_8250.h ++++ b/include/linux/serial_8250.h +@@ -7,6 +7,7 @@ + #ifndef _LINUX_SERIAL_8250_H + #define _LINUX_SERIAL_8250_H + ++#include <linux/atomic.h> + #include <linux/serial_core.h> + #include <linux/serial_reg.h> + #include <linux/platform_device.h> +@@ -124,6 +125,8 @@ struct uart_8250_port { + #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA + unsigned char msr_saved_flags; + ++ atomic_t console_printing; ++ + struct uart_8250_dma *dma; + const struct uart_8250_ops *ops; + +@@ -179,6 +182,8 @@ void serial8250_init_port(struct uart_8250_port *up); + void serial8250_set_defaults(struct uart_8250_port *up); + void serial8250_console_write(struct uart_8250_port *up, const char *s, + unsigned int count); ++void serial8250_console_write_atomic(struct uart_8250_port *up, const char *s, ++ unsigned int count); + int serial8250_console_setup(struct uart_port *port, char *options, bool probe); + int serial8250_console_exit(struct uart_port *port); + +-- +2.43.0 + |