Re: [PATCH v9 12/16] serial: amba-pl011: Pass FIQ information to KGDB.

[Peter Hurley <peter@hurleysoftware.com>]

Hi Daniel,

On 08/18/2014 10:28 AM, Daniel Thompson wrote:
> Speculatively register a FIQ resource with KGDB. KGDB will only
> accept it if the kgdb/fiq feature is enabled (both with compile time and
> runtime switches) and the interrupt controller supports FIQ.
> 
> By providing this information to KGDB the serial driver offers
> "permission" for KGDB to route the UART interrupt signal from the
> drivers own handler to KGDBs FIQ handler (which will eventually use the
> UART's polled I/O callbacks to interact with the user). This permission
> also implies the amba-pl011 driver has already unmasked RX interrupts
> (otherwise the FIQ handler will never trigger).
> 
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Jiri Slaby <jslaby@suse.cz>
> Cc: linux-serial@vger.kernel.org
> ---
>  drivers/tty/serial/amba-pl011.c | 94 ++++++++++++++++++++++++-----------------
>  1 file changed, 55 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 8572f2a..ec8ddc7 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -58,6 +58,7 @@
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/sizes.h>
>  #include <linux/io.h>
> +#include <linux/kgdb.h>
>  
>  #define UART_NR			14
>  
> @@ -1416,8 +1417,61 @@ static void pl011_break_ctl(struct uart_port *port, int break_state)
>  	spin_unlock_irqrestore(&uap->port.lock, flags);
>  }
>  

Is pl011_hwinit() just being relocated in source to avoid the forward
declaration? If so, this is usually split into its own commit.

> +static int pl011_hwinit(struct uart_port *port)
> +{
> +	struct uart_amba_port *uap = (struct uart_amba_port *)port;
> +	int retval;
> +
> +	/* Optionaly enable pins to be muxed in and configured */
> +	pinctrl_pm_select_default_state(port->dev);
> +
> +	/*
> +	 * Try to enable the clock producer.
> +	 */
> +	retval = clk_prepare_enable(uap->clk);
> +	if (retval)
> +		return retval;
> +
> +	uap->port.uartclk = clk_get_rate(uap->clk);
> +
> +	/* Clear pending error and receive interrupts */
> +	writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS |
> +	       UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
> +
> +	/*
> +	 * Save interrupts enable mask, and enable RX interrupts in case if
> +	 * the interrupt is used for NMI entry.
> +	 */
> +	uap->im = readw(uap->port.membase + UART011_IMSC);
> +	writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
> +
> +	if (dev_get_platdata(uap->port.dev)) {
> +		struct amba_pl011_data *plat;
> +
> +		plat = dev_get_platdata(uap->port.dev);
> +		if (plat->init)
> +			plat->init();
> +	}
> +	return 0;
> +}
> +
>  #ifdef CONFIG_CONSOLE_POLL
>  
> +static int pl011_poll_init(struct uart_port *port)
> +{
> +	struct uart_amba_port *uap = (struct uart_amba_port *)port;

Please use container_of() in new code.

> +	int retval;
> +
> +	retval = pl011_hwinit(port);
> +
> +#ifdef CONFIG_KGDB_FIQ
> +	if (retval == 0)
> +		kgdb_register_fiq(uap->port.irq);

The uap->port dereference is unnecessary since the port parameter
is the same thing.

		kgdb_register_fiq(port->irq);

Regards,
Peter Hurley

> +#endif
> +
> +	return retval;
> +}
> +
>  static void pl011_quiesce_irqs(struct uart_port *port)
>  {
>  	struct uart_amba_port *uap = (struct uart_amba_port *)port;
> @@ -1471,44 +1525,6 @@ static void pl011_put_poll_char(struct uart_port *port,
>  
>  #endif /* CONFIG_CONSOLE_POLL */
>  
> -static int pl011_hwinit(struct uart_port *port)
> -{
> -	struct uart_amba_port *uap = (struct uart_amba_port *)port;
> -	int retval;
> -
> -	/* Optionaly enable pins to be muxed in and configured */
> -	pinctrl_pm_select_default_state(port->dev);
> -
> -	/*
> -	 * Try to enable the clock producer.
> -	 */
> -	retval = clk_prepare_enable(uap->clk);
> -	if (retval)
> -		return retval;
> -
> -	uap->port.uartclk = clk_get_rate(uap->clk);
> -
> -	/* Clear pending error and receive interrupts */
> -	writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS |
> -	       UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
> -
> -	/*
> -	 * Save interrupts enable mask, and enable RX interrupts in case if
> -	 * the interrupt is used for NMI entry.
> -	 */
> -	uap->im = readw(uap->port.membase + UART011_IMSC);
> -	writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
> -
> -	if (dev_get_platdata(uap->port.dev)) {
> -		struct amba_pl011_data *plat;
> -
> -		plat = dev_get_platdata(uap->port.dev);
> -		if (plat->init)
> -			plat->init();
> -	}
> -	return 0;
> -}
> -
>  static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
>  {
>  	writew(lcr_h, uap->port.membase + uap->lcrh_rx);
> @@ -1888,7 +1904,7 @@ static struct uart_ops amba_pl011_pops = {
>  	.config_port	= pl011_config_port,
>  	.verify_port	= pl011_verify_port,
>  #ifdef CONFIG_CONSOLE_POLL
> -	.poll_init     = pl011_hwinit,
> +	.poll_init     = pl011_poll_init,
>  	.poll_get_char = pl011_get_poll_char,
>  	.poll_put_char = pl011_put_poll_char,
>  #endif
>