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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-15 22:58:58 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-15 22:58:58 +0300
commit486088bc4689f826b80aa317b45ac9e42e8b25ee (patch)
treeadf5847a6119d24da990d9e336f005c4a316e6be /Documentation/men-chameleon-bus.txt
parent52f6c588c77b76d548201470c2a28263a41b462b (diff)
parent43e5f7e1fa66531777c49791014c3124ea9208d8 (diff)
downloadlinux-486088bc4689f826b80aa317b45ac9e42e8b25ee.tar.xz
Merge tag 'standardize-docs' of git://git.lwn.net/linux
Pull documentation format standardization from Jonathan Corbet: "This series converts a number of top-level documents to the RST format without incorporating them into the Sphinx tree. The hope is to bring some uniformity to kernel documentation and, perhaps more importantly, have our existing docs serve as an example of the desired formatting for those that will be added later. Mauro has gone through and fixed up a lot of top-level documentation files to make them conform to the RST format, but without moving or renaming them in any way. This will help when we incorporate the ones we want to keep into the Sphinx doctree, but the real purpose is to bring a bit of uniformity to our documentation and let the top-level docs serve as examples for those writing new ones" * tag 'standardize-docs' of git://git.lwn.net/linux: (84 commits) docs: kprobes.txt: Fix whitespacing tee.txt: standardize document format cgroup-v2.txt: standardize document format dell_rbu.txt: standardize document format zorro.txt: standardize document format xz.txt: standardize document format xillybus.txt: standardize document format vfio.txt: standardize document format vfio-mediated-device.txt: standardize document format unaligned-memory-access.txt: standardize document format this_cpu_ops.txt: standardize document format svga.txt: standardize document format static-keys.txt: standardize document format smsc_ece1099.txt: standardize document format SM501.txt: standardize document format siphash.txt: standardize document format sgi-ioc4.txt: standardize document format SAK.txt: standardize document format rpmsg.txt: standardize document format robust-futexes.txt: standardize document format ...
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- MEN Chameleon Bus
- =================
-
-Table of Contents
=================
-1 Introduction
- 1.1 Scope of this Document
- 1.2 Limitations of the current implementation
-2 Architecture
- 2.1 MEN Chameleon Bus
- 2.2 Carrier Devices
- 2.3 Parser
-3 Resource handling
- 3.1 Memory Resources
- 3.2 IRQs
-4 Writing an MCB driver
- 4.1 The driver structure
- 4.2 Probing and attaching
- 4.3 Initializing the driver
-
-
-1 Introduction
-===============
- This document describes the architecture and implementation of the MEN
- Chameleon Bus (called MCB throughout this document).
-
-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 the complete possibilities of MCB
- based devices.
-
-1.2 Limitations of the current implementation
-----------------------------------------------
- The current implementation is limited to PCI and PCIe based carrier devices
- that only use a single memory resource and share the PCI legacy IRQ. Not
- implemented are:
- - Multi-resource MCB devices like the VME Controller or M-Module carrier.
- - MCB devices that need another MCB device, like SRAM for a DMA Controller's
- buffer descriptors or a video controller's video memory.
- - A per-carrier IRQ domain for carrier devices that have one (or more) IRQs
- per MCB device like PCIe based carriers with MSI or MSI-X support.
-
-2 Architecture
-===============
- 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
+MEN Chameleon Bus
+=================
+
+.. Table of Contents
+ =================
+ 1 Introduction
+ 1.1 Scope of this Document
+ 1.2 Limitations of the current implementation
+ 2 Architecture
+ 2.1 MEN Chameleon Bus
+ 2.2 Carrier Devices
+ 2.3 Parser
+ 3 Resource handling
+ 3.1 Memory Resources
+ 3.2 IRQs
+ 4 Writing an MCB driver
+ 4.1 The driver structure
+ 4.2 Probing and attaching
+ 4.3 Initializing the driver
+
+
+Introduction
+============
+
+This document describes the architecture and implementation of the MEN
+Chameleon Bus (called MCB throughout this document).
+
+Scope of this Document
----------------------
- 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
+
+This document is intended to be a short overview of the current
+implementation and does by no means describe the complete possibilities of MCB
+based devices.
+
+Limitations of the current implementation
+-----------------------------------------
+
+The current implementation is limited to PCI and PCIe based carrier devices
+that only use a single memory resource and share the PCI legacy IRQ. Not
+implemented are:
+
+- Multi-resource MCB devices like the VME Controller or M-Module carrier.
+- MCB devices that need another MCB device, like SRAM for a DMA Controller's
+ buffer descriptors or a video controller's video memory.
+- A per-carrier IRQ domain for carrier devices that have one (or more) IRQs
+ per MCB device like PCIe based carriers with MSI or MSI-X support.
+
+Architecture
+============
+
+MCB is divided into 3 functional blocks:
+
+- The MEN Chameleon Bus itself,
+- drivers for MCB Carrier Devices and
+- the parser for the Chameleon table.
+
+MEN Chameleon Bus
+-----------------
+
+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.
+
+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
+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 translated into a hardware bus
+query for the IRQ number the device should use.
+
+Parser
+------
+
+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
+MCB devices are registered at the MCB and thus at the driver core of the
+Linux kernel.
+
+Resource handling
+=================
+
+The current implementation assigns exactly one memory and one IRQ resource
+per MCB device. But this is likely going to change in the future.
+
+Memory Resources
+----------------
+
+Each MCB device has exactly one memory resource, which can be requested from
+the MCB bus. This memory resource is the physical address of the MCB device
+inside the carrier and is intended to be passed to ioremap() and friends. It
+is already requested from the kernel by calling request_mem_region().
+
+IRQs
+----
+
+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
+number is suitable to be passed to request_irq().
+
+Writing an MCB driver
+=====================
+
+The driver structure
--------------------
- 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
- 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 translated into a hardware bus
- query for the IRQ number the device should use.
-
-2.3 Parser
------------
- 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
- MCB devices are registered at the MCB and thus at the driver core of the
- Linux kernel.
-
-3 Resource handling
-====================
- The current implementation assigns exactly one memory and one IRQ resource
- per MCB device. But this is likely going to change in the future.
-
-3.1 Memory Resources
+
+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 contains callback methods which get executed on driver probe and
+removal from the system::
+
+ static const struct mcb_device_id foo_ids[] = {
+ { .device = 0x123 },
+ { }
+ };
+ MODULE_DEVICE_TABLE(mcb, foo_ids);
+
+ static struct mcb_driver foo_driver = {
+ driver = {
+ .name = "foo-bar",
+ .owner = THIS_MODULE,
+ },
+ .probe = foo_probe,
+ .remove = foo_remove,
+ .id_table = foo_ids,
+ };
+
+Probing and attaching
---------------------
- Each MCB device has exactly one memory resource, which can be requested from
- the MCB bus. This memory resource is the physical address of the MCB device
- inside the carrier and is intended to be passed to ioremap() and friends. It
- is already requested from the kernel by calling request_mem_region().
-
-3.2 IRQs
----------
- 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
- number is suitable to be passed to request_irq().
-
-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 contains callback methods which get executed on driver probe and
- removal from the system.
-
-
- static const struct mcb_device_id foo_ids[] = {
- { .device = 0x123 },
- { }
- };
- MODULE_DEVICE_TABLE(mcb, foo_ids);
-
- static struct mcb_driver foo_driver = {
- driver = {
- .name = "foo-bar",
- .owner = THIS_MODULE,
- },
- .probe = foo_probe,
- .remove = foo_remove,
- .id_table = foo_ids,
- };
-
-4.2 Probing and attaching
---------------------------
- When a driver is loaded and the MCB devices it services are found, the MCB
- core will call the driver's probe callback method. When the driver is removed
- from the system, the MCB core will call the driver's remove callback method.
-
-
- static init foo_probe(struct mcb_device *mdev, const struct mcb_device_id *id);
- static void foo_remove(struct mcb_device *mdev);
-
-4.3 Initializing the driver
-----------------------------
- When the kernel is booted or your foo driver module is inserted, you have to
- perform driver initialization. Usually it is enough to register your driver
- module at the MCB core.
-
-
- static int __init foo_init(void)
- {
- return mcb_register_driver(&foo_driver);
- }
- module_init(foo_init);
-
- static void __exit foo_exit(void)
- {
- mcb_unregister_driver(&foo_driver);
- }
- module_exit(foo_exit);
-
- The module_mcb_driver() macro can be used to reduce the above code.
-
-
- module_mcb_driver(foo_driver);
+
+When a driver is loaded and the MCB devices it services are found, the MCB
+core will call the driver's probe callback method. When the driver is removed
+from the system, the MCB core will call the driver's remove callback method::
+
+ static init foo_probe(struct mcb_device *mdev, const struct mcb_device_id *id);
+ static void foo_remove(struct mcb_device *mdev);
+
+Initializing the driver
+-----------------------
+
+When the kernel is booted or your foo driver module is inserted, you have to
+perform driver initialization. Usually it is enough to register your driver
+module at the MCB core::
+
+ static int __init foo_init(void)
+ {
+ return mcb_register_driver(&foo_driver);
+ }
+ module_init(foo_init);
+
+ static void __exit foo_exit(void)
+ {
+ mcb_unregister_driver(&foo_driver);
+ }
+ module_exit(foo_exit);
+
+The module_mcb_driver() macro can be used to reduce the above code::
+
+ module_mcb_driver(foo_driver);