[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/Documentation/spi/butterfly b/src/kernel/linux/v4.14/Documentation/spi/butterfly
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+spi_butterfly - parport-to-butterfly adapter driver
+===================================================
+
+This is a hardware and software project that includes building and using
+a parallel port adapter cable, together with an "AVR Butterfly" to run
+firmware for user interfacing and/or sensors. A Butterfly is a $US20
+battery powered card with an AVR microcontroller and lots of goodies:
+sensors, LCD, flash, toggle stick, and more. You can use AVR-GCC to
+develop firmware for this, and flash it using this adapter cable.
+
+You can make this adapter from an old printer cable and solder things
+directly to the Butterfly. Or (if you have the parts and skills) you
+can come up with something fancier, providing ciruit protection to the
+Butterfly and the printer port, or with a better power supply than two
+signal pins from the printer port. Or for that matter, you can use
+similar cables to talk to many AVR boards, even a breadboard.
+
+This is more powerful than "ISP programming" cables since it lets kernel
+SPI protocol drivers interact with the AVR, and could even let the AVR
+issue interrupts to them. Later, your protocol driver should work
+easily with a "real SPI controller", instead of this bitbanger.
+
+
+The first cable connections will hook Linux up to one SPI bus, with the
+AVR and a DataFlash chip; and to the AVR reset line. This is all you
+need to reflash the firmware, and the pins are the standard Atmel "ISP"
+connector pins (used also on non-Butterfly AVR boards). On the parport
+side this is like "sp12" programming cables.
+
+ Signal Butterfly Parport (DB-25)
+ ------ --------- ---------------
+ SCK = J403.PB1/SCK = pin 2/D0
+ RESET = J403.nRST = pin 3/D1
+ VCC = J403.VCC_EXT = pin 8/D6
+ MOSI = J403.PB2/MOSI = pin 9/D7
+ MISO = J403.PB3/MISO = pin 11/S7,nBUSY
+ GND = J403.GND = pin 23/GND
+
+Then to let Linux master that bus to talk to the DataFlash chip, you must
+(a) flash new firmware that disables SPI (set PRR.2, and disable pullups
+by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and
+(c) cable in the chipselect.
+
+ Signal Butterfly Parport (DB-25)
+ ------ --------- ---------------
+ VCC = J400.VCC_EXT = pin 7/D5
+ SELECT = J400.PB0/nSS = pin 17/C3,nSELECT
+ GND = J400.GND = pin 24/GND
+
+Or you could flash firmware making the AVR into an SPI slave (keeping the
+DataFlash in reset) and tweak the spi_butterfly driver to make it bind to
+the driver for your custom SPI-based protocol.
+
+The "USI" controller, using J405, can also be used for a second SPI bus.
+That would let you talk to the AVR using custom SPI-with-USI firmware,
+while letting either Linux or the AVR use the DataFlash. There are plenty
+of spare parport pins to wire this one up, such as:
+
+ Signal Butterfly Parport (DB-25)
+ ------ --------- ---------------
+ SCK = J403.PE4/USCK = pin 5/D3
+ MOSI = J403.PE5/DI = pin 6/D4
+ MISO = J403.PE6/DO = pin 12/S5,nPAPEROUT
+ GND = J403.GND = pin 22/GND
+
+ IRQ = J402.PF4 = pin 10/S6,ACK
+ GND = J402.GND(P2) = pin 25/GND
+