From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:44:01 +0206 Subject: [PATCH 044/134] serial: owl: Use port lock wrappers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz 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 Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-45-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/owl-uart.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) --- a/drivers/tty/serial/owl-uart.c +++ b/drivers/tty/serial/owl-uart.c @@ -125,12 +125,12 @@ static unsigned int owl_uart_tx_empty(st u32 val; unsigned int ret; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = owl_uart_read(port, OWL_UART_STAT); ret = (val & OWL_UART_STAT_TFES) ? TIOCSER_TEMT : 0; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return ret; } @@ -232,7 +232,7 @@ static irqreturn_t owl_uart_irq(int irq, unsigned long flags; u32 stat; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); stat = owl_uart_read(port, OWL_UART_STAT); @@ -246,7 +246,7 @@ static irqreturn_t owl_uart_irq(int irq, stat |= OWL_UART_STAT_RIP | OWL_UART_STAT_TIP; owl_uart_write(port, stat, OWL_UART_STAT); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return IRQ_HANDLED; } @@ -256,14 +256,14 @@ static void owl_uart_shutdown(struct uar u32 val; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = owl_uart_read(port, OWL_UART_CTL); val &= ~(OWL_UART_CTL_TXIE | OWL_UART_CTL_RXIE | OWL_UART_CTL_TXDE | OWL_UART_CTL_RXDE | OWL_UART_CTL_EN); owl_uart_write(port, val, OWL_UART_CTL); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); free_irq(port->irq, port); } @@ -279,7 +279,7 @@ static int owl_uart_startup(struct uart_ if (ret) return ret; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = owl_uart_read(port, OWL_UART_STAT); val |= OWL_UART_STAT_RIP | OWL_UART_STAT_TIP @@ -291,7 +291,7 @@ static int owl_uart_startup(struct uart_ val |= OWL_UART_CTL_EN; owl_uart_write(port, val, OWL_UART_CTL); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return 0; } @@ -311,7 +311,7 @@ static void owl_uart_set_termios(struct u32 ctl; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); ctl = owl_uart_read(port, OWL_UART_CTL); @@ -371,7 +371,7 @@ static void owl_uart_set_termios(struct uart_update_timeout(port, termios->c_cflag, baud); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static void owl_uart_release_port(struct uart_port *port) @@ -515,9 +515,9 @@ static void owl_uart_port_write(struct u 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; } @@ -541,7 +541,7 @@ static void owl_uart_port_write(struct u owl_uart_write(port, old_ctl, OWL_UART_CTL); if (locked) - spin_unlock(&port->lock); + uart_port_unlock(port); local_irq_restore(flags); }