From 348c0f05fb287f150e7eaa783c40cb73910f589d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:54 +0206 Subject: [PATCH 064/195] serial: meson: 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: Neil Armstrong Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-38-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/meson_uart.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c index 9388b9ddea3b..4c1d2089a0bb 100644 --- a/drivers/tty/serial/meson_uart.c +++ b/drivers/tty/serial/meson_uart.c @@ -129,14 +129,14 @@ static void meson_uart_shutdown(struct uart_port *port) free_irq(port->irq, port); - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = readl(port->membase + AML_UART_CONTROL); val &= ~AML_UART_RX_EN; val &= ~(AML_UART_RX_INT_EN | AML_UART_TX_INT_EN); writel(val, port->membase + AML_UART_CONTROL); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static void meson_uart_start_tx(struct uart_port *port) @@ -238,7 +238,7 @@ static irqreturn_t meson_uart_interrupt(int irq, void *dev_id) { struct uart_port *port = (struct uart_port *)dev_id; - spin_lock(&port->lock); + uart_port_lock(port); if (!(readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY)) meson_receive_chars(port); @@ -248,7 +248,7 @@ static irqreturn_t meson_uart_interrupt(int irq, void *dev_id) meson_uart_start_tx(port); } - spin_unlock(&port->lock); + uart_port_unlock(port); return IRQ_HANDLED; } @@ -284,7 +284,7 @@ static int meson_uart_startup(struct uart_port *port) u32 val; int ret = 0; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = readl(port->membase + AML_UART_CONTROL); val |= AML_UART_CLEAR_ERR; @@ -301,7 +301,7 @@ static int meson_uart_startup(struct uart_port *port) val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2)); writel(val, port->membase + AML_UART_MISC); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); ret = request_irq(port->irq, meson_uart_interrupt, 0, port->name, port); @@ -341,7 +341,7 @@ static void meson_uart_set_termios(struct uart_port *port, unsigned long flags; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); cflags = termios->c_cflag; iflags = termios->c_iflag; @@ -405,7 +405,7 @@ static void meson_uart_set_termios(struct uart_port *port, AML_UART_FRAME_ERR; uart_update_timeout(port, termios->c_cflag, baud); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int meson_uart_verify_port(struct uart_port *port, @@ -464,14 +464,14 @@ static int meson_uart_poll_get_char(struct uart_port *port) u32 c; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); if (readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY) c = NO_POLL_CHAR; else c = readl(port->membase + AML_UART_RFIFO); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return c; } @@ -482,7 +482,7 @@ static void meson_uart_poll_put_char(struct uart_port *port, unsigned char c) u32 reg; int ret; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* Wait until FIFO is empty or timeout */ ret = readl_poll_timeout_atomic(port->membase + AML_UART_STATUS, reg, @@ -506,7 +506,7 @@ static void meson_uart_poll_put_char(struct uart_port *port, unsigned char c) dev_err(port->dev, "Timeout waiting for UART TX EMPTY\n"); out: - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } #endif /* CONFIG_CONSOLE_POLL */ @@ -563,9 +563,9 @@ static void meson_serial_port_write(struct uart_port *port, const char *s, if (port->sysrq) { locked = 0; } else if (oops_in_progress) { - locked = spin_trylock(&port->lock); + locked = uart_port_trylock(port); } else { - spin_lock(&port->lock); + uart_port_lock(port); locked = 1; } @@ -577,7 +577,7 @@ static void meson_serial_port_write(struct uart_port *port, const char *s, writel(val, port->membase + AML_UART_CONTROL); if (locked) - spin_unlock(&port->lock); + uart_port_unlock(port); local_irq_restore(flags); } -- 2.43.0