Re: [PATCH 01/28] serial: earlycon: allow MEM32 I/O for DT earlycon

[Rob Herring]

On Mon, Nov 30, 2015 at 10:21 AM, Paul Burton <paul.burton@xxxxxxxxxx> wrote:
> Read the reg-io-width property when earlycon is setup via device tree,
> and set the I/O type to UPIO_MEM32 when 4 is read. This behaviour
> matches that of the of_serial driver, and is needed for DT configured
> earlycon on the MIPS Boston board.
>
> Note that this is only possible when CONFIG_LIBFDT is enabled, but
> enabling it everywhere seems like overkill. Thus systems that need this
> functionality should select CONFIG_LIBFDT for themselves.

libfdt is enabled if you are booting from DT, so checking this
property should not add anything.

>
> Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
> ---
>
>  drivers/of/fdt.c              |  2 +-
>  drivers/tty/serial/Makefile   |  1 +
>  drivers/tty/serial/earlycon.c | 15 ++++++++++++++-
>  include/linux/serial_core.h   |  2 +-
>  4 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index d243029..71c7f0d 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -833,7 +833,7 @@ static int __init early_init_dt_scan_chosen_serial(void)
>                 if (addr == OF_BAD_ADDR)
>                         return -ENXIO;
>
> -               of_setup_earlycon(addr, match->data);
> +               of_setup_earlycon(fdt, offset, addr, match->data);
>                 return 0;
>         }
>         return -ENODEV;
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index 5ab4111..1d290d6 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_SERIAL_21285) += 21285.o
>
>  obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
>  obj-$(CONFIG_SERIAL_EARLYCON_ARM_SEMIHOST) += earlycon-arm-semihost.o
> +CFLAGS_earlycon.o += -I$(srctree)/scripts/dtc/libfdt

This is no longer necessary.

>
>  # These Sparc drivers have to appear before others such as 8250
>  # which share ttySx minor node space.  Otherwise console device
> diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> index f096360..2b936a7 100644
> --- a/drivers/tty/serial/earlycon.c
> +++ b/drivers/tty/serial/earlycon.c
> @@ -17,6 +17,7 @@
>  #include <linux/kernel.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> +#include <linux/libfdt.h>
>  #include <linux/serial_core.h>
>  #include <linux/sizes.h>
>  #include <linux/mod_devicetable.h>
> @@ -196,17 +197,29 @@ static int __init param_setup_earlycon(char *buf)
>  }
>  early_param("earlycon", param_setup_earlycon);
>
> -int __init of_setup_earlycon(unsigned long addr,
> +int __init of_setup_earlycon(const void *fdt, int offset, unsigned long addr,

I would add iotype as a parameter instead, and then...

>                              int (*setup)(struct earlycon_device *, const char *))
>  {
>         int err;
>         struct uart_port *port = &early_console_dev.port;
> +       const __be32 *prop;
>
>         port->iotype = UPIO_MEM;
>         port->mapbase = addr;
>         port->uartclk = BASE_BAUD * 16;
>         port->membase = earlycon_map(addr, SZ_4K);
>
> +       if (config_enabled(CONFIG_LIBFDT)) {
> +               prop = fdt_getprop(fdt, offset, "reg-io-width", NULL);
> +               if (prop) {
> +                       switch (be32_to_cpup(prop)) {
> +                       case 4:
> +                               port->iotype = UPIO_MEM32;
> +                               break;
> +                       }
> +               }

...move this parsing into fdt.c where we parse the address.

Rob
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