From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:33 +0206 Subject: [PATCH 016/134] serial: amba-pl010: 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/20230914183831.587273-17-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/amba-pl010.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/drivers/tty/serial/amba-pl010.c +++ b/drivers/tty/serial/amba-pl010.c @@ -207,7 +207,7 @@ static irqreturn_t pl010_int(int irq, vo unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT; int handled = 0; - spin_lock(&port->lock); + uart_port_lock(port); status = readb(port->membase + UART010_IIR); if (status) { @@ -228,7 +228,7 @@ static irqreturn_t pl010_int(int irq, vo handled = 1; } - spin_unlock(&port->lock); + uart_port_unlock(port); return IRQ_RETVAL(handled); } @@ -270,14 +270,14 @@ static void pl010_break_ctl(struct uart_ unsigned long flags; unsigned int lcr_h; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); lcr_h = readb(port->membase + UART010_LCRH); if (break_state == -1) lcr_h |= UART01x_LCRH_BRK; else lcr_h &= ~UART01x_LCRH_BRK; writel(lcr_h, port->membase + UART010_LCRH); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int pl010_startup(struct uart_port *port) @@ -385,7 +385,7 @@ pl010_set_termios(struct uart_port *port if (port->fifosize > 1) lcr_h |= UART01x_LCRH_FEN; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* * Update the per-port timeout. @@ -438,22 +438,22 @@ pl010_set_termios(struct uart_port *port writel(lcr_h, port->membase + UART010_LCRH); writel(old_cr, port->membase + UART010_CR); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static void pl010_set_ldisc(struct uart_port *port, struct ktermios *termios) { if (termios->c_line == N_PPS) { port->flags |= UPF_HARDPPS_CD; - spin_lock_irq(&port->lock); + uart_port_lock_irq(port); pl010_enable_ms(port); - spin_unlock_irq(&port->lock); + uart_port_unlock_irq(port); } else { port->flags &= ~UPF_HARDPPS_CD; if (!UART_ENABLE_MS(port, termios->c_cflag)) { - spin_lock_irq(&port->lock); + uart_port_lock_irq(port); pl010_disable_ms(port); - spin_unlock_irq(&port->lock); + uart_port_unlock_irq(port); } } }