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

[Alexander Graf <agraf@suse.de>]

On 17.01.18 20:46, Simon Glass wrote:
> Hi Alex,
> 
> On 17 January 2018 at 00:54, Alexander Graf <agraf@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@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().

Yes, but what if users specify the serial device to be pre-reloc and
don't do that for the GPIO (or really pinctrl) one? Then we'd not have
the driver around to determine whether serial is active, right?


Alex