iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

serial: mcf: Use port lock wrappers

Browse Source 
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 <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230914183831.587273-36-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Gleixner 2023-09-14 20:43:52 +02:06 committed by Greg Kroah-Hartman
parent 1b42626add
commit f78a6f1374
1 changed files with 10 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/tty/serial/mcf.c
View File

@ -135,12 +135,12 @@ static void mcf_break_ctl(struct uart_port *port, int break_state)
{
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
uart_port_lock_irqsave(port, &flags);
if (break_state == -1)
writeb(MCFUART_UCR_CMDBREAKSTART, port->membase + MCFUART_UCR);
else
writeb(MCFUART_UCR_CMDBREAKSTOP, port->membase + MCFUART_UCR);
spin_unlock_irqrestore(&port->lock, flags);
uart_port_unlock_irqrestore(port, flags);
}
/****************************************************************************/
@ -150,7 +150,7 @@ static int mcf_startup(struct uart_port *port)
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
uart_port_lock_irqsave(port, &flags);
/* Reset UART, get it into known state... */
writeb(MCFUART_UCR_CMDRESETRX, port->membase + MCFUART_UCR);
@ -164,7 +164,7 @@ static int mcf_startup(struct uart_port *port)
pp->imr = MCFUART_UIR_RXREADY;
writeb(pp->imr, port->membase + MCFUART_UIMR);
spin_unlock_irqrestore(&port->lock, flags);
uart_port_unlock_irqrestore(port, flags);
return 0;
}
@ -176,7 +176,7 @@ static void mcf_shutdown(struct uart_port *port)
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
uart_port_lock_irqsave(port, &flags);
/* Disable all interrupts now */
pp->imr = 0;
@ -186,7 +186,7 @@ static void mcf_shutdown(struct uart_port *port)
writeb(MCFUART_UCR_CMDRESETRX, port->membase + MCFUART_UCR);
writeb(MCFUART_UCR_CMDRESETTX, port->membase + MCFUART_UCR);
spin_unlock_irqrestore(&port->lock, flags);
uart_port_unlock_irqrestore(port, flags);
}
/****************************************************************************/
@ -252,7 +252,7 @@ static void mcf_set_termios(struct uart_port *port, struct ktermios *termios,
mr2 |= MCFUART_MR2_TXCTS;
}
spin_lock_irqsave(&port->lock, flags);
uart_port_lock_irqsave(port, &flags);
if (port->rs485.flags & SER_RS485_ENABLED) {
dev_dbg(port->dev, "Setting UART to RS485\n");
mr2 |= MCFUART_MR2_TXRTS;
@ -273,7 +273,7 @@ static void mcf_set_termios(struct uart_port *port, struct ktermios *termios,
port->membase + MCFUART_UCSR);
writeb(MCFUART_UCR_RXENABLE | MCFUART_UCR_TXENABLE,
port->membase + MCFUART_UCR);
spin_unlock_irqrestore(&port->lock, flags);
uart_port_unlock_irqrestore(port, flags);
}
/****************************************************************************/
@ -350,7 +350,7 @@ static irqreturn_t mcf_interrupt(int irq, void *data)
isr = readb(port->membase + MCFUART_UISR) & pp->imr;
spin_lock(&port->lock);
uart_port_lock(port);
if (isr & MCFUART_UIR_RXREADY) {
mcf_rx_chars(pp);
ret = IRQ_HANDLED;
@ -359,7 +359,7 @@ static irqreturn_t mcf_interrupt(int irq, void *data)
mcf_tx_chars(pp);
ret = IRQ_HANDLED;
}
spin_unlock(&port->lock);
uart_port_unlock(port);
return ret;
}