Based on kernel version 4.2. Page generated on 2015-09-09 12:15 EST.
1 What is smsc-ece1099? 2 ---------------------- 3 4 The ECE1099 is a 40-Pin 3.3V Keyboard Scan Expansion 5 or GPIO Expansion device. The device supports a keyboard 6 scan matrix of 23x8. The device is connected to a Master 7 via the SMSC BC-Link interface or via the SMBus. 8 Keypad scan Input(KSI) and Keypad Scan Output(KSO) signals 9 are multiplexed with GPIOs. 10 11 Interrupt generation 12 -------------------- 13 14 Interrupts can be generated by an edge detection on a GPIO 15 pin or an edge detection on one of the bus interface pins. 16 Interrupts can also be detected on the keyboard scan interface. 17 The bus interrupt pin (BC_INT# or SMBUS_INT#) is asserted if 18 any bit in one of the Interrupt Status registers is 1 and 19 the corresponding Interrupt Mask bit is also 1. 20 21 In order for software to determine which device is the source 22 of an interrupt, it should first read the Group Interrupt Status Register 23 to determine which Status register group is a source for the interrupt. 24 Software should read both the Status register and the associated Mask register, 25 then AND the two values together. Bits that are 1 in the result of the AND 26 are active interrupts. Software clears an interrupt by writing a 1 to the 27 corresponding bit in the Status register. 28 29 Communication Protocol 30 ---------------------- 31 32 - SMbus slave Interface 33 The host processor communicates with the ECE1099 device 34 through a series of read/write registers via the SMBus 35 interface. SMBus is a serial communication protocol between 36 a computer host and its peripheral devices. The SMBus data 37 rate is 10KHz minimum to 400 KHz maximum 38 39 - Slave Bus Interface 40 The ECE1099 device SMBus implementation is a subset of the 41 SMBus interface to the host. The device is a slave-only SMBus device. 42 The implementation in the device is a subset of SMBus since it 43 only supports four protocols. 44 45 The Write Byte, Read Byte, Send Byte, and Receive Byte protocols are the 46 only valid SMBus protocols for the device. 47 48 - BC-LinkTM Interface 49 The BC-Link is a proprietary bus that allows communication 50 between a Master device and a Companion device. The Master 51 device uses this serial bus to read and write registers 52 located on the Companion device. The bus comprises three signals, 53 BC_CLK, BC_DAT and BC_INT#. The Master device always provides the 54 clock, BC_CLK, and the Companion device is the source for an 55 independent asynchronous interrupt signal, BC_INT#. The ECE1099 56 supports BC-Link speeds up to 24MHz.