From 26615e1b2f4ca9d476f48425474b3b860963ebc2 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Thu, 14 Sep 2023 20:43:53 +0206 Subject: [PATCH 062/204] serial: men_z135_uart: 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> Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20230914183831.587273-37-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/men_z135_uart.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) Index: linux-6.6.58-rt45/drivers/tty/serial/men_z135_uart.c =================================================================== @ linux-6.6.58-rt45/drivers/tty/serial/men_z135_uart.c:395 @ static irqreturn_t men_z135_intr(int irq if (!irq_id) goto out; - spin_lock(&port->lock); + uart_port_lock(port); /* It's save to write to IIR[7:6] RXC[9:8] */ iowrite8(irq_id, port->membase + MEN_Z135_STAT_REG); @ linux-6.6.58-rt45/drivers/tty/serial/men_z135_uart.c:421 @ static irqreturn_t men_z135_intr(int irq handled = true; } - spin_unlock(&port->lock); + uart_port_unlock(port); out: return IRQ_RETVAL(handled); } @ linux-6.6.58-rt45/drivers/tty/serial/men_z135_uart.c:711 @ static void men_z135_set_termios(struct baud = uart_get_baud_rate(port, termios, old, 0, uart_freq / 16); - spin_lock_irq(&port->lock); + uart_port_lock_irq(port); if (tty_termios_baud_rate(termios)) tty_termios_encode_baud_rate(termios, baud, baud); @ linux-6.6.58-rt45/drivers/tty/serial/men_z135_uart.c:719 @ static void men_z135_set_termios(struct iowrite32(bd_reg, port->membase + MEN_Z135_BAUD_REG); uart_update_timeout(port, termios->c_cflag, baud); - spin_unlock_irq(&port->lock); + uart_port_unlock_irq(port); } static const char *men_z135_type(struct uart_port *port)