path: root/Documentation/smsc_ece1099.txt
diff options
authorSourav Poddar <sourav.poddar@ti.com>2012-10-01 16:31:22 +0530
committerSamuel Ortiz <sameo@linux.intel.com>2012-10-01 15:27:48 +0200
commit8284328cd98b9ac9eebf646e6fcb9047bc12bf55 (patch)
tree1c7ab08de0e003d300ab194512cb2847a971b45a /Documentation/smsc_ece1099.txt
parentc6bed9deb6047179a6c58ace847f8b2129085e37 (diff)
mfd: smsc: Add support for smsc gpio io/keypad driver
smsc ece1099 is a keyboard scan or gpio expansion device. The patch create keypad and gpio expander child for this multi function smsc driver. Cc: Benoit Cousson <b-cousson@ti.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Santosh Shilimkar <santosh.shilimkar@ti.com> Signed-off-by: Sourav Poddar <sourav.poddar@ti.com> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
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+What is smsc-ece1099?
+The ECE1099 is a 40-Pin 3.3V Keyboard Scan Expansion
+or GPIO Expansion device. The device supports a keyboard
+scan matrix of 23x8. The device is connected to a Master
+via the SMSC BC-Link interface or via the SMBus.
+Keypad scan Input(KSI) and Keypad Scan Output(KSO) signals
+are multiplexed with GPIOs.
+Interrupt generation
+Interrupts can be generated by an edge detection on a GPIO
+pin or an edge detection on one of the bus interface pins.
+Interrupts can also be detected on the keyboard scan interface.
+The bus interrupt pin (BC_INT# or SMBUS_INT#) is asserted if
+any bit in one of the Interrupt Status registers is 1 and
+the corresponding Interrupt Mask bit is also 1.
+In order for software to determine which device is the source
+of an interrupt, it should first read the Group Interrupt Status Register
+to determine which Status register group is a source for the interrupt.
+Software should read both the Status register and the associated Mask register,
+then AND the two values together. Bits that are 1 in the result of the AND
+are active interrupts. Software clears an interrupt by writing a 1 to the
+corresponding bit in the Status register.
+Communication Protocol
+- SMbus slave Interface
+ The host processor communicates with the ECE1099 device
+ through a series of read/write registers via the SMBus
+ interface. SMBus is a serial communication protocol between
+ a computer host and its peripheral devices. The SMBus data
+ rate is 10KHz minimum to 400 KHz maximum
+- Slave Bus Interface
+ The ECE1099 device SMBus implementation is a subset of the
+ SMBus interface to the host. The device is a slave-only SMBus device.
+ The implementation in the device is a subset of SMBus since it
+ only supports four protocols.
+ The Write Byte, Read Byte, Send Byte, and Receive Byte protocols are the
+ only valid SMBus protocols for the device.
+- BC-LinkTM Interface
+ The BC-Link is a proprietary bus that allows communication
+ between a Master device and a Companion device. The Master
+ device uses this serial bus to read and write registers
+ located on the Companion device. The bus comprises three signals,
+ BC_CLK, BC_DAT and BC_INT#. The Master device always provides the
+ clock, BC_CLK, and the Companion device is the source for an
+ independent asynchronous interrupt signal, BC_INT#. The ECE1099
+ supports BC-Link speeds up to 24MHz.

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