From 21620ba2a3e2d1adb81a40fd2a3b7c2bdda4258f Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Thu, 14 Sep 2023 20:43:54 +0206 Subject: [PATCH 063/204] 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 <tglx@linutronix.de> Acked-by: Neil Armstrong <neil.armstrong@linaro.org> Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20230914183831.587273-38-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/tty/serial/meson_uart.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) Index: linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c =================================================================== @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:132 @ static void meson_uart_shutdown(struct u 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) @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:241 @ static irqreturn_t meson_uart_interrupt( { 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); @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:251 @ static irqreturn_t meson_uart_interrupt( meson_uart_start_tx(port); } - spin_unlock(&port->lock); + uart_port_unlock(port); return IRQ_HANDLED; } @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:287 @ static int meson_uart_startup(struct uar 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; @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:304 @ static int meson_uart_startup(struct uar 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); @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:344 @ static void meson_uart_set_termios(struc 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; @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:408 @ static void meson_uart_set_termios(struc 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, @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:467 @ static int meson_uart_poll_get_char(stru 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; } @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:485 @ static void meson_uart_poll_put_char(str 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, @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:509 @ static void meson_uart_poll_put_char(str 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 */ @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:566 @ static void meson_serial_port_write(stru 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; } @ linux-6.6.58-rt45/drivers/tty/serial/meson_uart.c:580 @ static void meson_serial_port_write(stru writel(val, port->membase + AML_UART_CONTROL); if (locked) - spin_unlock(&port->lock); + uart_port_unlock(port); local_irq_restore(flags); }