From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:22 +0206 Subject: [PATCH 005/134] serial: 8250_bcm7271: 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/20230914183831.587273-6-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/8250/8250_bcm7271.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) --- a/drivers/tty/serial/8250/8250_bcm7271.c +++ b/drivers/tty/serial/8250/8250_bcm7271.c @@ -567,7 +567,7 @@ static irqreturn_t brcmuart_isr(int irq, if (interrupts == 0) return IRQ_NONE; - spin_lock_irqsave(&up->lock, flags); + uart_port_lock_irqsave(up, &flags); /* Clear all interrupts */ udma_writel(priv, REGS_DMA_ISR, UDMA_INTR_CLEAR, interrupts); @@ -581,7 +581,7 @@ static irqreturn_t brcmuart_isr(int irq, if ((rval | tval) == 0) dev_warn(dev, "Spurious interrupt: 0x%x\n", interrupts); - spin_unlock_irqrestore(&up->lock, flags); + uart_port_unlock_irqrestore(up, flags); return IRQ_HANDLED; } @@ -608,10 +608,10 @@ static int brcmuart_startup(struct uart_ * * Synchronize UART_IER access against the console. */ - spin_lock_irq(&port->lock); + uart_port_lock_irq(port); up->ier &= ~UART_IER_RDI; serial_port_out(port, UART_IER, up->ier); - spin_unlock_irq(&port->lock); + uart_port_unlock_irq(port); priv->tx_running = false; priv->dma.rx_dma = NULL; @@ -629,7 +629,7 @@ static void brcmuart_shutdown(struct uar struct brcmuart_priv *priv = up->port.private_data; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); priv->shutdown = true; if (priv->dma_enabled) { stop_rx_dma(up); @@ -645,7 +645,7 @@ static void brcmuart_shutdown(struct uar */ up->dma = NULL; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); serial8250_do_shutdown(port); } @@ -788,7 +788,7 @@ static int brcmuart_handle_irq(struct ua * interrupt but there is no data ready. */ if (((iir & UART_IIR_ID) == UART_IIR_RX_TIMEOUT) && !(priv->shutdown)) { - spin_lock_irqsave(&p->lock, flags); + uart_port_lock_irqsave(p, &flags); status = serial_port_in(p, UART_LSR); if ((status & UART_LSR_DR) == 0) { @@ -813,7 +813,7 @@ static int brcmuart_handle_irq(struct ua handled = 1; } - spin_unlock_irqrestore(&p->lock, flags); + uart_port_unlock_irqrestore(p, flags); if (handled) return 1; } @@ -831,7 +831,7 @@ static enum hrtimer_restart brcmuart_hrt if (priv->shutdown) return HRTIMER_NORESTART; - spin_lock_irqsave(&p->lock, flags); + uart_port_lock_irqsave(p, &flags); status = serial_port_in(p, UART_LSR); /* @@ -855,7 +855,7 @@ static enum hrtimer_restart brcmuart_hrt status |= UART_MCR_RTS; serial_port_out(p, UART_MCR, status); } - spin_unlock_irqrestore(&p->lock, flags); + uart_port_unlock_irqrestore(p, flags); return HRTIMER_NORESTART; } @@ -1154,10 +1154,10 @@ static int __maybe_unused brcmuart_suspe * This will prevent resume from enabling RTS before the * baud rate has been restored. */ - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); priv->saved_mctrl = port->mctrl; port->mctrl &= ~TIOCM_RTS; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); serial8250_suspend_port(priv->line); clk_disable_unprepare(priv->baud_mux_clk); @@ -1196,10 +1196,10 @@ static int __maybe_unused brcmuart_resum if (priv->saved_mctrl & TIOCM_RTS) { /* Restore RTS */ - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); port->mctrl |= TIOCM_RTS; port->ops->set_mctrl(port, port->mctrl); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } return 0;