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| author | Jonathan Corbet <corbet@lwn.net> | 2016-08-20 22:24:56 +0300 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2016-09-06 17:48:07 +0300 |
| commit | 70fc1f547a91c137913a23a0f7a4a89c33930c6a (patch) | |
| tree | 3bd2d3cd3af7ba92d129dc6648f698ce5314f7d0 /Documentation/hsi.txt | |
| parent | dcec3c8c9aea9e779c59f420465381c0f3322913 (diff) | |
| download | linux-70fc1f547a91c137913a23a0f7a4a89c33930c6a.tar.xz | |
docs: Pull the HSI documentation together
The HSI subsystem documentation was split across hsi.txt and the
device-drivers docbook. Now that the latter has been converted to Sphinx,
pull in the HSI document so that it's all in one place.
Acked-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/hsi.txt')
| -rw-r--r-- | Documentation/hsi.txt | 75 |
1 files changed, 0 insertions, 75 deletions
diff --git a/Documentation/hsi.txt b/Documentation/hsi.txt deleted file mode 100644 index 6ac6cd51852a..000000000000 --- a/Documentation/hsi.txt +++ /dev/null @@ -1,75 +0,0 @@ -HSI - High-speed Synchronous Serial Interface - -1. Introduction -~~~~~~~~~~~~~~~ - -High Speed Syncronous Interface (HSI) is a fullduplex, low latency protocol, -that is optimized for die-level interconnect between an Application Processor -and a Baseband chipset. It has been specified by the MIPI alliance in 2003 and -implemented by multiple vendors since then. - -The HSI interface supports full duplex communication over multiple channels -(typically 8) and is capable of reaching speeds up to 200 Mbit/s. - -The serial protocol uses two signals, DATA and FLAG as combined data and clock -signals and an additional READY signal for flow control. An additional WAKE -signal can be used to wakeup the chips from standby modes. The signals are -commonly prefixed by AC for signals going from the application die to the -cellular die and CA for signals going the other way around. - -+------------+ +---------------+ -| Cellular | | Application | -| Die | | Die | -| | - - - - - - CAWAKE - - - - - - >| | -| T|------------ CADATA ------------>|R | -| X|------------ CAFLAG ------------>|X | -| |<----------- ACREADY ------------| | -| | | | -| | | | -| |< - - - - - ACWAKE - - - - - - -| | -| R|<----------- ACDATA -------------|T | -| X|<----------- ACFLAG -------------|X | -| |------------ CAREADY ----------->| | -| | | | -| | | | -+------------+ +---------------+ - -2. HSI Subsystem in Linux -~~~~~~~~~~~~~~~~~~~~~~~~~ - -In the Linux kernel the hsi subsystem is supposed to be used for HSI devices. -The hsi subsystem contains drivers for hsi controllers including support for -multi-port controllers and provides a generic API for using the HSI ports. - -It also contains HSI client drivers, which make use of the generic API to -implement a protocol used on the HSI interface. These client drivers can -use an arbitrary number of channels. - -3. hsi-char Device -~~~~~~~~~~~~~~~~~~ - -Each port automatically registers a generic client driver called hsi_char, -which provides a charecter device for userspace representing the HSI port. -It can be used to communicate via HSI from userspace. Userspace may -configure the hsi_char device using the following ioctl commands: - -* HSC_RESET: - - flush the HSI port - -* HSC_SET_PM - - enable or disable the client. - -* HSC_SEND_BREAK - - send break - -* HSC_SET_RX - - set RX configuration - -* HSC_GET_RX - - get RX configuration - -* HSC_SET_TX - - set TX configuration - -* HSC_GET_TX - - get TX configuration |