2015-08-22 02:01:03 +08:00
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.. _basic_atom:
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Platform Configuration: basic_atom
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##################################
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Overview
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********
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The basic_atom platform configuration is used by Zephyr applications
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that run on QEMU emulating the Atom N28xx platform. This platform
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configuration provides support for an x86 Atom CPU and the following devices:
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* HPET
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* Advanced Programmed Interrupt Controller (APIC)
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* NS16550 UART
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.. note::
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This platform configuration makes no claims about its suitability for use
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with an actual Atom N28xx hardware system, or any other hardware system.
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Supported Boards
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****************
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The basic_atom platform configuration has been tested on QEMU 2.1.
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Supported Features
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******************
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The basic_atom platform configuration supports the following
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hardware features:
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+--------------+------------+-----------------------+
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| Interface | Controller | Driver/Component |
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+==============+============+=======================+
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| HPET | on-chip | system clock |
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+--------------+------------+-----------------------+
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| APIC | on-chip | interrupt controller |
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+--------------+------------+-----------------------+
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| NS16550 | on-chip | serial port |
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| UART | | |
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+--------------+------------+-----------------------+
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2015-09-17 06:04:00 +08:00
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The kernel currently does not support other hardware features on this platform.
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2015-08-22 02:01:03 +08:00
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Interrupt Controller
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====================
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2015-09-17 06:04:00 +08:00
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Refer to the :ref:`galileo`.
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2015-08-22 02:01:03 +08:00
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.. note::
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The basic_atom platform configuration does not support PCI.
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HPET System Clock Support
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=========================
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The basic_atom platform configuration uses a system
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clock frequency of 25 MHz.
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.. note::
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2015-09-17 06:04:00 +08:00
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The LOAPIC timer may be used instead of the HPET. To do so,
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set SYS_CLOCK_HW_CYCLES_PER_SEC to a custom value that is tied to the host system speed.
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2015-08-22 02:01:03 +08:00
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Serial Port
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===========
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2015-09-17 06:04:00 +08:00
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The basic_atom platform configuration uses a single serial communication channel
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with a NS16550 serial driver that operates in polling mode.
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For an interrupt-driven driver, enable the UART_INTERRUPT_DRIVEN kernel configuration option.
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2015-08-22 02:01:03 +08:00
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Known Problems or Limitations
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*****************************
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2015-09-17 06:04:00 +08:00
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The following platform features are unsupported:
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2015-08-22 02:01:03 +08:00
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* Isolated Memory Regions
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* Serial port in Direct Memory Access (DMA) mode
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* Serial Peripheral Interface (SPI) flash
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* General-Purpose Input/Output (GPIO)
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* Inter-Integrated Circuit (I2C)
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* Ethernet
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* Supervisor Mode Execution Protection (SMEP)
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