- 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);
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