[U-Boot] [PATCH v5 5/9] arm: serial: Add ability to use pre-initialized UARTs

[Simon Glass]

Hi Sergey,

On 7 September 2015 at 09:18, Sergey Temerkhanov
<s.temerkhanov at gmail.com> wrote:
> On some systems, UART initialization is performed before running U-Boot.
> This commit allows to skip UART re-initializaion on those systems
>
> Signed-off-by: Sergey Temerkhanov <s.temerkhanov at gmail.com>
> Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla at cavium.com>
>
> ---
>
> Changes in v5:
> - Added OF control support
>
> Changes in v4:
> - Fixed build warnings
> - Moved to DM_SERIAL
>
> Changes in v3:
> - Added __used keyword
>
> Changes in v2: None
>
>  drivers/serial/serial_pl01x.c           | 13 +++++++------
>  include/dm/platform_data/serial_pl01x.h |  6 ++++++
>  2 files changed, 13 insertions(+), 6 deletions(-)

Reviewed-by: Simon Glass <sjg at chromium.org>

But please see one issue below. Also you might consider implementing
the debug UART for this driver so you get early debugging,

>
> diff --git a/drivers/serial/serial_pl01x.c b/drivers/serial/serial_pl01x.c
> index ecf3bc0..83151e0 100644
> --- a/drivers/serial/serial_pl01x.c
> +++ b/drivers/serial/serial_pl01x.c
> @@ -125,7 +125,7 @@ static int pl011_set_line_control(struct pl01x_regs *regs)
>  }
>
>  static int pl01x_generic_setbrg(struct pl01x_regs *regs, enum pl01x_type type,
> -                               int clock, int baudrate)
> +                                      int clock, int baudrate)
>  {
>         switch (type) {
>         case TYPE_PL010: {
> @@ -295,7 +295,6 @@ __weak struct serial_device *default_serial_console(void)
>  #endif /* nCONFIG_DM_SERIAL */
>
>  #ifdef CONFIG_DM_SERIAL
> -
>  struct pl01x_priv {
>         struct pl01x_regs *regs;
>         enum pl01x_type type;
> @@ -306,9 +305,9 @@ static int pl01x_serial_setbrg(struct udevice *dev, int baudrate)
>         struct pl01x_serial_platdata *plat = dev_get_platdata(dev);
>         struct pl01x_priv *priv = dev_get_priv(dev);
>
> -       pl01x_generic_setbrg(priv->regs, priv->type, plat->clock, baudrate);
> -
> -       return 0;
> +       return (plat->flags & PL0X_PREINITIALIZED) ? 0 :
> +               pl01x_generic_setbrg(priv->regs, priv->type,
> +                                    plat->clock, baudrate);
>  }
>
>  static int pl01x_serial_probe(struct udevice *dev)
> @@ -318,7 +317,8 @@ static int pl01x_serial_probe(struct udevice *dev)
>
>         priv->regs = (struct pl01x_regs *)plat->base;
>         priv->type = plat->type;
> -       return pl01x_generic_serial_init(priv->regs, priv->type);
> +       return (plat->flags & PL0X_PREINITIALIZED) ? 0 :
> +               pl01x_generic_serial_init(priv->regs, priv->type);
>  }
>
>  static int pl01x_serial_getc(struct udevice *dev)
> @@ -372,6 +372,7 @@ static int pl01x_serial_ofdata_to_platdata(struct udevice *dev)
>         plat->base = addr;
>         plat->clock = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "clock", 1);
>         plat->type = dev_get_driver_data(dev);
> +       plat->flags = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "flags", 0);

Can I suggest a boolean option here, like u-boot,skip-init? You can
use fdtdec_get_bool() to read it. Also please add it to
doc/device-tree-bindings/serial/pl01x.txt.

>         return 0;
>  }
>  #endif
> diff --git a/include/dm/platform_data/serial_pl01x.h b/include/dm/platform_data/serial_pl01x.h
> index 5e068f3..73e1be0 100644
> --- a/include/dm/platform_data/serial_pl01x.h
> +++ b/include/dm/platform_data/serial_pl01x.h
> @@ -11,17 +11,23 @@ enum pl01x_type {
>         TYPE_PL011,
>  };
>
> +enum pl01x_flags {
> +       PL0X_PREINITIALIZED = 1 << 0, /* Skip port initialization */
> +};
> +
>  /*
>   *Information about a serial port
>   *
>   * @base: Register base address
>   * @type: Port type
>   * @clock: Input clock rate, used for calculating the baud rate divisor
> + * @flags: Port flags
>   */
>  struct pl01x_serial_platdata {
>         unsigned long base;
>         enum pl01x_type type;
>         unsigned int clock;
> +       unsigned long flags;
>  };
>
>  #endif
> --
> 2.2.0
>

Regards,
Simon