From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:44:19 +0206 Subject: [PATCH 062/134] serial: sprd: 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/20230914183831.587273-63-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/sprd_serial.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) --- a/drivers/tty/serial/sprd_serial.c +++ b/drivers/tty/serial/sprd_serial.c @@ -247,7 +247,7 @@ static void sprd_complete_tx_dma(void *d struct circ_buf *xmit = &port->state->xmit; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); dma_unmap_single(port->dev, sp->tx_dma.phys_addr, sp->tx_dma.trans_len, DMA_TO_DEVICE); @@ -260,7 +260,7 @@ static void sprd_complete_tx_dma(void *d sprd_tx_dma_config(port)) sp->tx_dma.trans_len = 0; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int sprd_uart_dma_submit(struct uart_port *port, @@ -429,13 +429,13 @@ static void sprd_complete_rx_dma(void *d enum dma_status status; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); status = dmaengine_tx_status(sp->rx_dma.chn, sp->rx_dma.cookie, &state); if (status != DMA_COMPLETE) { sprd_stop_rx(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return; } @@ -449,7 +449,7 @@ static void sprd_complete_rx_dma(void *d if (sprd_start_dma_rx(port)) sprd_stop_rx(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int sprd_start_dma_rx(struct uart_port *port) @@ -638,12 +638,12 @@ static irqreturn_t sprd_handle_irq(int i struct uart_port *port = dev_id; unsigned int ims; - spin_lock(&port->lock); + uart_port_lock(port); ims = serial_in(port, SPRD_IMSR); if (!ims) { - spin_unlock(&port->lock); + uart_port_unlock(port); return IRQ_NONE; } @@ -660,7 +660,7 @@ static irqreturn_t sprd_handle_irq(int i if (ims & SPRD_IMSR_TX_FIFO_EMPTY) sprd_tx(port); - spin_unlock(&port->lock); + uart_port_unlock(port); return IRQ_HANDLED; } @@ -727,13 +727,13 @@ static int sprd_startup(struct uart_port serial_out(port, SPRD_CTL1, fc); /* enable interrupt */ - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); ien = serial_in(port, SPRD_IEN); ien |= SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT; if (!sp->rx_dma.enable) ien |= SPRD_IEN_RX_FULL; serial_out(port, SPRD_IEN, ien); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return 0; } @@ -793,7 +793,7 @@ static void sprd_set_termios(struct uart lcr |= SPRD_LCR_EVEN_PAR; } - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* update the per-port timeout */ uart_update_timeout(port, termios->c_cflag, baud); @@ -837,7 +837,7 @@ static void sprd_set_termios(struct uart fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF; serial_out(port, SPRD_CTL1, fc); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); /* Don't rewrite B0 */ if (tty_termios_baud_rate(termios)) @@ -974,9 +974,9 @@ static void sprd_console_write(struct co if (port->sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock_irqsave(&port->lock, flags); + locked = uart_port_trylock_irqsave(port, &flags); else - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); uart_console_write(port, s, count, sprd_console_putchar); @@ -984,7 +984,7 @@ static void sprd_console_write(struct co wait_for_xmitr(port); if (locked) - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int sprd_console_setup(struct console *co, char *options)