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Documentation / smsc_ece1099.txt




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Based on kernel version 4.13.3. Page generated on 2017-09-23 13:56 EST.

1	=================================================
2	Msc Keyboard Scan Expansion/GPIO Expansion device
3	=================================================
4	
5	What is smsc-ece1099?
6	----------------------
7	
8	The ECE1099 is a 40-Pin 3.3V Keyboard Scan Expansion
9	or GPIO Expansion device. The device supports a keyboard
10	scan matrix of 23x8. The device is connected to a Master
11	via the SMSC BC-Link interface or via the SMBus.
12	Keypad scan Input(KSI) and Keypad Scan Output(KSO) signals
13	are multiplexed with GPIOs.
14	
15	Interrupt generation
16	--------------------
17	
18	Interrupts can be generated by an edge detection on a GPIO
19	pin or an edge detection on one of the bus interface pins.
20	Interrupts can also be detected on the keyboard scan interface.
21	The bus interrupt pin (BC_INT# or SMBUS_INT#) is asserted if
22	any bit in one of the Interrupt Status registers is 1 and
23	the corresponding Interrupt Mask bit is also 1.
24	
25	In order for software to determine which device is the source
26	of an interrupt, it should first read the Group Interrupt Status Register
27	to determine which Status register group is a source for the interrupt.
28	Software should read both the Status register and the associated Mask register,
29	then AND the two values together. Bits that are 1 in the result of the AND
30	are active interrupts. Software clears an interrupt by writing a 1 to the
31	corresponding bit in the Status register.
32	
33	Communication Protocol
34	----------------------
35	
36	- SMbus slave Interface
37		The host processor communicates with the ECE1099 device
38		through a series of read/write registers via the SMBus
39		interface. SMBus is a serial communication protocol between
40		a computer host and its peripheral devices. The SMBus data
41		rate is 10KHz minimum to 400 KHz maximum
42	
43	- Slave Bus Interface
44		The ECE1099 device SMBus implementation is a subset of the
45		SMBus interface to the host. The device is a slave-only SMBus device.
46		The implementation in the device is a subset of SMBus since it
47		only supports four protocols.
48	
49		The Write Byte, Read Byte, Send Byte, and Receive Byte protocols are the
50		only valid SMBus protocols for the device.
51	
52	- BC-LinkTM Interface
53		The BC-Link is a proprietary bus that allows communication
54		between a Master device and a Companion device. The Master
55		device uses this serial bus to read and write registers
56		located on the Companion device. The bus comprises three signals,
57		BC_CLK, BC_DAT and BC_INT#. The Master device always provides the
58		clock, BC_CLK, and the Companion device is the source for an
59		independent asynchronous interrupt signal, BC_INT#. The ECE1099
60		supports BC-Link speeds up to 24MHz.
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