From f874ed9f1662ee8fabfebd26a21932420fe8519b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:49 +0206 Subject: [PATCH 059/195] serial: liteuart: Use port lock wrappers When a serial port is used for kernel console output, then all modifications to the UART registers which are done from other contexts, e.g. getty, termios, are interference points for the kernel console. So far this has been ignored and the printk output is based on the principle of hope. The rework of the console infrastructure which aims to support threaded and atomic consoles, requires to mark sections which modify the UART registers as unsafe. This allows the atomic write function to make informed decisions and eventually to restore operational state. It also allows to prevent the regular UART code from modifying UART registers while printk output is in progress. All modifications of UART registers are guarded by the UART port lock, which provides an obvious synchronization point with the console infrastructure. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner Acked-by: Gabriel Somlo Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-33-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/liteuart.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c index d881cdd2a58f..a25ab1efe38f 100644 --- a/drivers/tty/serial/liteuart.c +++ b/drivers/tty/serial/liteuart.c @@ -139,13 +139,13 @@ static irqreturn_t liteuart_interrupt(int irq, void *data) * if polling, the context would be "in_serving_softirq", so use * irq[save|restore] spin_lock variants to cover all possibilities */ - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); isr = litex_read8(port->membase + OFF_EV_PENDING) & uart->irq_reg; if (isr & EV_RX) liteuart_rx_chars(port); if (isr & EV_TX) liteuart_tx_chars(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return IRQ_RETVAL(isr); } @@ -195,10 +195,10 @@ static int liteuart_startup(struct uart_port *port) } } - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* only enabling rx irqs during startup */ liteuart_update_irq_reg(port, true, EV_RX); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); if (!port->irq) { timer_setup(&uart->timer, liteuart_timer, 0); @@ -213,9 +213,9 @@ static void liteuart_shutdown(struct uart_port *port) struct liteuart_port *uart = to_liteuart_port(port); unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); liteuart_update_irq_reg(port, false, EV_RX | EV_TX); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); if (port->irq) free_irq(port->irq, port); @@ -229,13 +229,13 @@ static void liteuart_set_termios(struct uart_port *port, struct ktermios *new, unsigned int baud; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* update baudrate */ baud = uart_get_baud_rate(port, new, old, 0, 460800); uart_update_timeout(port, new->c_cflag, baud); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static const char *liteuart_type(struct uart_port *port) @@ -382,9 +382,9 @@ static void liteuart_console_write(struct console *co, const char *s, uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index); port = &uart->port; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); uart_console_write(port, s, count, liteuart_putchar); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int liteuart_console_setup(struct console *co, char *options) -- 2.43.0