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Documentation: Minor changes to men-chameleon-bus.txt

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Change men-chameleon-bus.txt according to the comments made by Randy Dunlap in
https://lkml.org/lkml/2015/7/17/691.

These are:
* Some minor gramatical changes
* Spelling fixes
* Write the word "Chameleon" capitalized throughout the whole document
* Explain MEN as MEN Mikro Elektronik GmbH.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Johannes Thumshirn 2015-07-23 11:17:26 +02:00 committed by Jonathan Corbet
parent 013542caa8
commit 7c97211b61
1 changed files with 20 additions and 19 deletions
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Documentation/men-chameleon-bus.txt
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@ -13,7 +13,7 @@ Table of Contents
3 Resource handling
3.1 Memory Resources
3.2 IRQs
4 Writing a MCB driver
4 Writing an MCB driver
4.1 The driver structure
4.2 Probing and attaching
4.3 Initializing the driver
@ -27,7 +27,7 @@ Table of Contents
1.1 Scope of this Document
---------------------------
This document is intended to be a short overview of the current
implementation and does by no means describe to complete possibilities of MCB
implementation and does by no means describe the complete possibilities of MCB
based devices.
1.2 Limitations of the current implementation
@ -43,40 +43,41 @@ Table of Contents
2 Architecture
===============
MCB is divided in 3 functional blocks:
MCB is divided into 3 functional blocks:
- The MEN Chameleon Bus itself,
- drivers for MCB Carrier Devices and
- the parser for the Chameleon table.
2.1 MEN Chameleon Bus
----------------------
The MEN Chameleon Bus is an artificial bus system that attaches to an MEN
Chameleon FPGA device. These devices are multi-function devices implemented
in a single FPGA and usually attached via some sort of PCI or PCIe link. Each
FPGA contains a header section describing the content of the FPGA. The header
lists the device id, PCI BAR, offset from the beginning of the PCI BAR, size
in the FPGA, interrupt number and some other properties currently not handled
by the MCB implementation.
The MEN Chameleon Bus is an artificial bus system that attaches to a so
called Chameleon FPGA device found on some hardware produced my MEN Mikro
Elektronik GmbH. These devices are multi-function devices implemented in a
single FPGA and usually attached via some sort of PCI or PCIe link. Each
FPGA contains a header section describing the content of the FPGA. The
header lists the device id, PCI BAR, offset from the beginning of the PCI
BAR, size in the FPGA, interrupt number and some other properties currently
not handled by the MCB implementation.
2.2 Carrier Devices
--------------------
A carrier device is just an abstraction for the real world physical bus the
chameleon FPGA is attached to. Some IP Core drivers may need to interact with
Chameleon FPGA is attached to. Some IP Core drivers may need to interact with
properties of the carrier device (like querying the IRQ number of a PCI
device). To provide abstraction from the real hardware bus, an MCB carrier
device provides callback methods to translate the driver's MCB function calls
to hardware related function calls. For example a carrier device may
implement the get_irq() method which can be translate into a hardware bus
implement the get_irq() method which can be translated into a hardware bus
query for the IRQ number the device should use.
2.3 Parser
-----------
The parser reads the 1st 512 bytes of a chameleon device and parses the
chameleon table. Currently the parser only supports the Chameleon v2 variant
of the chameleon table but can easily be adopted to support an older or
The parser reads the first 512 bytes of a Chameleon device and parses the
Chameleon table. Currently the parser only supports the Chameleon v2 variant
of the Chameleon table but can easily be adopted to support an older or
possible future variant. While parsing the table's entries new MCB devices
are allocated and their resources are assigned according to the resource
assignment in the chameleon table. After resource assignment is finished, the
assignment in the Chameleon table. After resource assignment is finished, the
MCB devices are registered at the MCB and thus at the driver core of the
Linux kernel.
@ -97,17 +98,17 @@ Table of Contents
Each MCB device has exactly one IRQ resource, which can be requested from the
MCB bus. If a carrier device driver implements the ->get_irq() callback
method, the IRQ number assigned by the carrier device will be returned,
otherwise the IRQ number inside the chameleon table will be returned. This
otherwise the IRQ number inside the Chameleon table will be returned. This
number is suitable to be passed to request_irq().
4 Writing a MCB driver
4 Writing an MCB driver
=======================
4.1 The driver structure
-------------------------
Each MCB driver has a structure to identify the device driver as well as
device ids which identify the IP Core inside the FPGA. The driver structure
also contaings callback methods which get executed on driver probe and
also contains callback methods which get executed on driver probe and
removal from the system.