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author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-06-27 15:39:22 -0300 |
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committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-07-15 11:03:02 -0300 |
commit | baa293e9544bea71361950d071579f0e4d5713ed (patch) | |
tree | 29e0400c806016783a3fd7a380be40a201956653 /Documentation/driver-api/smsc_ece1099.rst | |
parent | 4f4cfa6c560c93ba180c30675cf845e1597de44c (diff) | |
download | linux-baa293e9544bea71361950d071579f0e4d5713ed.tar.bz2 |
docs: driver-api: add a series of orphaned documents
There are lots of documents under Documentation/*.txt and a few other
orphan documents elsehwere that belong to the driver-API book.
Move them to their right place.
Reviewed-by: Cornelia Huck <cohuck@redhat.com> # vfio-related parts
Acked-by: Logan Gunthorpe <logang@deltatee.com> # switchtec
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/driver-api/smsc_ece1099.rst')
-rw-r--r-- | Documentation/driver-api/smsc_ece1099.rst | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/Documentation/driver-api/smsc_ece1099.rst b/Documentation/driver-api/smsc_ece1099.rst new file mode 100644 index 000000000000..079277421eaf --- /dev/null +++ b/Documentation/driver-api/smsc_ece1099.rst @@ -0,0 +1,60 @@ +================================================= +Msc Keyboard Scan Expansion/GPIO Expansion device +================================================= + +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. |