Re: [PATCH] serial: 8250_uniphier: add earlycon support

Peter Hurley
2015-10-28T15:21:08Z

Hi Masahiro,

On 10/22/2015 04:39 AM, Masahiro Yamada wrote:
> This reuses the code of drivers/tty/serial/8250/8250_early.c except
>
> - Overwrite device->port.iotype and device->port.regshift for
> UPIO_MEM32 because of_setup_earlycon() has set them for UPIO_MEM.
>
> - Set device->baud to zero to prevent early8250_setup() from
> initializing the divisor register because port->uartclk does not
> match the frequency expected by this hardware.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
> drivers/tty/serial/8250/8250_uniphier.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
> index 245edbb..c1075c5 100644
> --- a/drivers/tty/serial/8250/8250_uniphier.c
> +++ b/drivers/tty/serial/8250/8250_uniphier.c
> @@ -13,6 +13,7 @@
> */
>
> #include <linux/clk.h>
> +#include <linux/console.h>
> #include <linux/io.h>
> #include <linux/module.h>
> #include <linux/of.h>
> @@ -34,6 +35,29 @@ struct uniphier8250_priv {
> spinlock_t atomic_write_lock;
> };
>
> +#if IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE)

#ifdef CONFIG_SERIAL_8250_CONSOLE

Customarily, IS_ENABLED() is only used in-function with control flow
statements; eg.,

if (IS_ENABLED() && .... )
....

> +static int __init uniphier_early_console_setup(struct earlycon_device *device,
> + const char *options)
> +{
> + if (!device->port.membase)
> + return -ENODEV;
> +
> + /* This hardware always expects MMIO32 register interface. */
> + device->port.iotype = UPIO_MEM32;
> + device->port.regshift = 2;
> +
> + /*
> + * Do not touch the divisor register in early_serial8250_setup();
> + * we assume it has been initialized by a boot loader.
> + */
> + device->baud = 0;
> +
> + return early_serial8250_setup(device, options);
> +}
> +OF_EARLYCON_DECLARE(uniphier_uart, "socionext,uniphier-uart",
> + uniphier_early_console_setup);

Please change the earlycon name to just "uniphier" or "uniphier8250"; eg.,

OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
uniphier_early_console_setup);

My earlycon series merges OF_EARLYCON_DECLARE() => EARLYCON_DECLARE()
and "uniphier" is simpler on the command line.

Regards,
Peter Hurley

> +#endif
> +
> /*
> * The register map is slightly different from that of 8250.
> * IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
>