Recent microbit firmwares panic if the TWI magnetometer/accelerometer
devices are not detected during startup.  We don't implement TWI (I2C)
so let's stub out these devices just to let the firmware boot.

Signed-off by: Steffen Görtz <contrib@steffen-goertz.de>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190110094020.18354-2-stefanha@redhat.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: fixed comment style]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Wire up nRF51 UART in the corresponding SoC.
Signed-off-by: NJulia Suvorova <jusual@mail.ru>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NAlistair Francis <alistair.francis@wdc.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

This adds the base for a machine model of the BBC micro:bit:

  https://en.wikipedia.org/wiki/Micro_Bit

This is a system with a nRF51 SoC containing the main processor, with
various peripherals on board.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NJoel Stanley <joel@jms.id.au>
Message-id: 20180831220920.27113-4-joel@jms.id.au
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>