[U-Boot] [PATCH v2 5/7] rpi: Properly detect which serial device is active

[Simon Glass]

Hi Alex,

On 17 January 2018 at 00:54, Alexander Graf <agraf at suse.de> wrote:
> Now that we have all infrastructure in place to dynamically determine whether
> a serial device is actually usable (read: routed to user accessible pins), we
> can wire it up to the board.
>
> This patch adds support to determine whether the pl011 or mini-uart or no serial
> is routed to the UART RX/TX pins on the Raspberry Pi family of boards.
>
> Signed-off-by: Alexander Graf <agraf at suse.de>
> ---
>  board/raspberrypi/rpi/rpi.c | 69 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
>
> diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
> index a96d5d8952..b0cdad70f7 100644
> --- a/board/raspberrypi/rpi/rpi.c
> +++ b/board/raspberrypi/rpi/rpi.c
> @@ -24,9 +24,16 @@
>  #include <asm/armv8/mmu.h>
>  #endif
>  #include <watchdog.h>
> +#include <asm/io.h>
>
>  DECLARE_GLOBAL_DATA_PTR;
>
> +/*
> + * This is the GPIO pin that the user facing UART RX line is attached to.
> + * We use this pin to determine which serial device is available.
> + */
> +#define BCM2835_GPIO_RX                15
> +
>  /* From lowlevel_init.S */
>  extern unsigned long fw_dtb_pointer;
>
> @@ -419,6 +426,68 @@ static void get_board_rev(void)
>         printf("RPI %s (0x%x)\n", model->name, revision);
>  }
>
> +/*
> + * We may get called before the device model is initialized, so we can not
> + * rely on the GPIO driver.
> + */
> +int get_func_id(unsigned gpio)
> +{
> +       u32 val;
> +       u32 node;
> +       u32 *gpfsel;
> +       fdt_addr_t addr;
> +       fdt_size_t size;
> +
> +       node = fdt_node_offset_by_compatible(gd->fdt_blob, -1, "brcm,bcm2835-gpio");
> +       if (node < 0)
> +               return -EINVAL;
> +
> +       addr = fdtdec_get_addr_size_auto_noparent(gd->fdt_blob, node, "reg",
> +                                                 0, &size, true);
> +       gpfsel = (void*)addr;
> +
> +       val = readl(&gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
> +
> +       return (val >> BCM2835_GPIO_FSEL_SHIFT(gpio) & BCM2835_GPIO_FSEL_MASK);
> +}

Ick, this should be done in the GPIO driver and use gpio_get_function().

Regards,
Simon