From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:44:03 +0206 Subject: [PATCH 046/134] serial: pic32: 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/20230914183831.587273-47-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/pic32_uart.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/drivers/tty/serial/pic32_uart.c +++ b/drivers/tty/serial/pic32_uart.c @@ -243,7 +243,7 @@ static void pic32_uart_break_ctl(struct struct pic32_sport *sport = to_pic32_sport(port); unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); if (ctl) pic32_uart_writel(sport, PIC32_SET(PIC32_UART_STA), @@ -252,7 +252,7 @@ static void pic32_uart_break_ctl(struct pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA), PIC32_UART_STA_UTXBRK); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } /* get port type in string format */ @@ -274,7 +274,7 @@ static void pic32_uart_do_rx(struct uart */ max_count = PIC32_UART_RX_FIFO_DEPTH; - spin_lock(&port->lock); + uart_port_lock(port); tty = &port->state->port; @@ -331,7 +331,7 @@ static void pic32_uart_do_rx(struct uart } while (--max_count); - spin_unlock(&port->lock); + uart_port_unlock(port); tty_flip_buffer_push(tty); } @@ -410,9 +410,9 @@ static irqreturn_t pic32_uart_tx_interru struct uart_port *port = dev_id; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); pic32_uart_do_tx(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return IRQ_HANDLED; } @@ -580,9 +580,9 @@ static void pic32_uart_shutdown(struct u unsigned long flags; /* disable uart */ - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); pic32_uart_dsbl_and_mask(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); clk_disable_unprepare(sport->clk); /* free all 3 interrupts for this UART */ @@ -604,7 +604,7 @@ static void pic32_uart_set_termios(struc unsigned int quot; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* disable uart and mask all interrupts while changing speed */ pic32_uart_dsbl_and_mask(port); @@ -672,7 +672,7 @@ static void pic32_uart_set_termios(struc /* enable uart */ pic32_uart_en_and_unmask(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } /* serial core request to claim uart iomem */