History log of /openbmc/qemu/hw/fsi/fsi-master.c (Results 1 – 7 of 7)
Revision (<<< Hide revision tags) (Show revision tags >>>) Date Author Comments
# 2e50d22b 28-Nov-2023 Ninad Palsule <ninad@linux.ibm.com>

hw/fsi: Introduce IBM's FSI master

This is a part of patchset where IBM's Flexible Service Interface is
introduced.

This commit models the FSI master. CFAM is hanging out of FSI master which is a b

hw/fsi: Introduce IBM's FSI master

This is a part of patchset where IBM's Flexible Service Interface is
introduced.

This commit models the FSI master. CFAM is hanging out of FSI master which is a bus controller.

The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

[ clg: - move FSICFAMState object under FSIMasterState
- introduced fsi_master_init()
- reworked fsi_master_realize()
- dropped FSIBus definition ]

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...


# 37d5505a 16-Aug-2023 Andrew Jeffery <andrew@aj.id.au>

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for some fun with inter-processor buses. FSI allows a service
processor access to the internal busses of a host POWER processor to
perform configuration or debugging.

FSI has long existed in POWER processes and so comes with some baggage,
including how it has been integrated into the ASPEED SoC.

Working backwards from the POWER processor, the fundamental pieces of
interest for the implementation are:

1. The Common FRU Access Macro (CFAM), an address space containing
various "engines" that drive accesses on busses internal and external
to the POWER chip. Examples include the SBEFIFO and I2C masters. The
engines hang off of an internal Local Bus (LBUS) which is described
by the CFAM configuration block.

2. The FSI slave: The slave is the terminal point of the FSI bus for
FSI symbols addressed to it. Slaves can be cascaded off of one
another. The slave's configuration registers appear in address space
of the CFAM to which it is attached.

3. The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

4. The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

5. An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The implementation appears as following in the qemu device tree:

(qemu) info qtree
bus: main-system-bus
type System
...
dev: aspeed.apb2opb, id ""
gpio-out "sysbus-irq" 1
mmio 000000001e79b000/0000000000001000
bus: opb.1
type opb
dev: fsi.master, id ""
bus: fsi.bus.1
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.1
type lbus
dev: scratchpad, id ""
address = 0 (0x0)
bus: opb.0
type opb
dev: fsi.master, id ""
bus: fsi.bus.0
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.0
type lbus
dev: scratchpad, id ""
address = 0 (0x0)

The LBUS is modelled to maintain the qdev bus hierarchy and to take
advantage of the object model to automatically generate the CFAM
configuration block. The configuration block presents engines in the
order they are attached to the CFAM's LBUS. Engine implementations
should subclass the LBusDevice and set the 'config' member of
LBusDeviceClass to match the engine's type.

CFAM designs offer a lot of flexibility, for instance it is possible for
a CFAM to be simultaneously driven from multiple FSI links. The modeling
is not so complete; it's assumed that each CFAM is attached to a single
FSI slave (as a consequence the CFAM subclasses the FSI slave).

As for FSI, its symbols and wire-protocol are not modelled at all. This
is not necessary to get FSI off the ground thanks to the mapping of the
CFAM address space onto the OPB address space - the models follow this
directly and map the CFAM memory region into the OPB's memory region.
Future work includes supporting more advanced accesses that drive the
FSI master directly rather than indirectly via the CFAM mapping, which
will require implementing the FSI state machine and methods for each of
the FSI symbols on the slave. Further down the track we can also look at
supporting the bitbanged SoftFSI drivers in Linux by extending the FSI
slave model to resolve sequences of GPIO IRQs into FSI symbols, and
calling the associated symbol method on the slave to map the access onto
the CFAM.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: tons of fixes, lots of love and care and time.
we need to split this patch ! ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...


Revision tags: v8.0.0
# f69f73e1 13-Apr-2023 Andrew Jeffery <andrew@aj.id.au>

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for some fun with inter-processor buses. FSI allows a service
processor access to the internal busses of a host POWER processor to
perform configuration or debugging.

FSI has long existed in POWER processes and so comes with some baggage,
including how it has been integrated into the ASPEED SoC.

Working backwards from the POWER processor, the fundamental pieces of
interest for the implementation are:

1. The Common FRU Access Macro (CFAM), an address space containing
various "engines" that drive accesses on busses internal and external
to the POWER chip. Examples include the SBEFIFO and I2C masters. The
engines hang off of an internal Local Bus (LBUS) which is described
by the CFAM configuration block.

2. The FSI slave: The slave is the terminal point of the FSI bus for
FSI symbols addressed to it. Slaves can be cascaded off of one
another. The slave's configuration registers appear in address space
of the CFAM to which it is attached.

3. The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

4. The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

5. An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The implementation appears as following in the qemu device tree:

(qemu) info qtree
bus: main-system-bus
type System
...
dev: aspeed.apb2opb, id ""
gpio-out "sysbus-irq" 1
mmio 000000001e79b000/0000000000001000
bus: opb.1
type opb
dev: fsi.master, id ""
bus: fsi.bus.1
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.1
type lbus
dev: scratchpad, id ""
address = 0 (0x0)
bus: opb.0
type opb
dev: fsi.master, id ""
bus: fsi.bus.0
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.0
type lbus
dev: scratchpad, id ""
address = 0 (0x0)

The LBUS is modelled to maintain the qdev bus hierarchy and to take
advantage of the object model to automatically generate the CFAM
configuration block. The configuration block presents engines in the
order they are attached to the CFAM's LBUS. Engine implementations
should subclass the LBusDevice and set the 'config' member of
LBusDeviceClass to match the engine's type.

CFAM designs offer a lot of flexibility, for instance it is possible for
a CFAM to be simultaneously driven from multiple FSI links. The modeling
is not so complete; it's assumed that each CFAM is attached to a single
FSI slave (as a consequence the CFAM subclasses the FSI slave).

As for FSI, its symbols and wire-protocol are not modelled at all. This
is not necessary to get FSI off the ground thanks to the mapping of the
CFAM address space onto the OPB address space - the models follow this
directly and map the CFAM memory region into the OPB's memory region.
Future work includes supporting more advanced accesses that drive the
FSI master directly rather than indirectly via the CFAM mapping, which
will require implementing the FSI state machine and methods for each of
the FSI symbols on the slave. Further down the track we can also look at
supporting the bitbanged SoftFSI drivers in Linux by extending the FSI
slave model to resolve sequences of GPIO IRQs into FSI symbols, and
calling the associated symbol method on the slave to map the access onto
the CFAM.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: tons of fixes, lots of love and care and time.
we need to split this patch ! ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...


Revision tags: v7.2.0
# 13dc434e 05-Dec-2022 Andrew Jeffery <andrew@aj.id.au>

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for some fun with inter-processor buses. FSI allows a service
processor access to the internal busses of a host POWER processor to
perform configuration or debugging.

FSI has long existed in POWER processes and so comes with some baggage,
including how it has been integrated into the ASPEED SoC.

Working backwards from the POWER processor, the fundamental pieces of
interest for the implementation are:

1. The Common FRU Access Macro (CFAM), an address space containing
various "engines" that drive accesses on busses internal and external
to the POWER chip. Examples include the SBEFIFO and I2C masters. The
engines hang off of an internal Local Bus (LBUS) which is described
by the CFAM configuration block.

2. The FSI slave: The slave is the terminal point of the FSI bus for
FSI symbols addressed to it. Slaves can be cascaded off of one
another. The slave's configuration registers appear in address space
of the CFAM to which it is attached.

3. The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

4. The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

5. An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The implementation appears as following in the qemu device tree:

(qemu) info qtree
bus: main-system-bus
type System
...
dev: aspeed.apb2opb, id ""
gpio-out "sysbus-irq" 1
mmio 000000001e79b000/0000000000001000
bus: opb.1
type opb
dev: fsi.master, id ""
bus: fsi.bus.1
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.1
type lbus
dev: scratchpad, id ""
address = 0 (0x0)
bus: opb.0
type opb
dev: fsi.master, id ""
bus: fsi.bus.0
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.0
type lbus
dev: scratchpad, id ""
address = 0 (0x0)

The LBUS is modelled to maintain the qdev bus hierarchy and to take
advantage of the object model to automatically generate the CFAM
configuration block. The configuration block presents engines in the
order they are attached to the CFAM's LBUS. Engine implementations
should subclass the LBusDevice and set the 'config' member of
LBusDeviceClass to match the engine's type.

CFAM designs offer a lot of flexibility, for instance it is possible for
a CFAM to be simultaneously driven from multiple FSI links. The modeling
is not so complete; it's assumed that each CFAM is attached to a single
FSI slave (as a consequence the CFAM subclasses the FSI slave).

As for FSI, its symbols and wire-protocol are not modelled at all. This
is not necessary to get FSI off the ground thanks to the mapping of the
CFAM address space onto the OPB address space - the models follow this
directly and map the CFAM memory region into the OPB's memory region.
Future work includes supporting more advanced accesses that drive the
FSI master directly rather than indirectly via the CFAM mapping, which
will require implementing the FSI state machine and methods for each of
the FSI symbols on the slave. Further down the track we can also look at
supporting the bitbanged SoftFSI drivers in Linux by extending the FSI
slave model to resolve sequences of GPIO IRQs into FSI symbols, and
calling the associated symbol method on the slave to map the access onto
the CFAM.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: tons of fixes, lots of love and care and time/
we need to split this patch ! ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...


# 606987e4 20-Apr-2022 Andrew Jeffery <andrew@aj.id.au>

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for some fun with inter-processor buses. FSI allows a service
processor access to the internal busses of a host POWER processor to
perform configuration or debugging.

FSI has long existed in POWER processes and so comes with some baggage,
including how it has been integrated into the ASPEED SoC.

Working backwards from the POWER processor, the fundamental pieces of
interest for the implementation are:

1. The Common FRU Access Macro (CFAM), an address space containing
various "engines" that drive accesses on busses internal and external
to the POWER chip. Examples include the SBEFIFO and I2C masters. The
engines hang off of an internal Local Bus (LBUS) which is described
by the CFAM configuration block.

2. The FSI slave: The slave is the terminal point of the FSI bus for
FSI symbols addressed to it. Slaves can be cascaded off of one
another. The slave's configuration registers appear in address space
of the CFAM to which it is attached.

3. The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

4. The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

5. An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The implementation appears as following in the qemu device tree:

(qemu) info qtree
bus: main-system-bus
type System
...
dev: aspeed.apb2opb, id ""
gpio-out "sysbus-irq" 1
mmio 000000001e79b000/0000000000001000
bus: opb.1
type opb
dev: fsi.master, id ""
bus: fsi.bus.1
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.1
type lbus
dev: scratchpad, id ""
address = 0 (0x0)
bus: opb.0
type opb
dev: fsi.master, id ""
bus: fsi.bus.0
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.0
type lbus
dev: scratchpad, id ""
address = 0 (0x0)

The LBUS is modelled to maintain the qdev bus hierarchy and to take
advantage of the object model to automatically generate the CFAM
configuration block. The configuration block presents engines in the
order they are attached to the CFAM's LBUS. Engine implementations
should subclass the LBusDevice and set the 'config' member of
LBusDeviceClass to match the engine's type.

CFAM designs offer a lot of flexibility, for instance it is possible for
a CFAM to be simultaneously driven from multiple FSI links. The modeling
is not so complete; it's assumed that each CFAM is attached to a single
FSI slave (as a consequence the CFAM subclasses the FSI slave).

As for FSI, its symbols and wire-protocol are not modelled at all. This
is not necessary to get FSI off the ground thanks to the mapping of the
CFAM address space onto the OPB address space - the models follow this
directly and map the CFAM memory region into the OPB's memory region.
Future work includes supporting more advanced accesses that drive the
FSI master directly rather than indirectly via the CFAM mapping, which
will require implementing the FSI state machine and methods for each of
the FSI symbols on the slave. Further down the track we can also look at
supporting the bitbanged SoftFSI drivers in Linux by extending the FSI
slave model to resolve sequences of GPIO IRQs into FSI symbols, and
calling the associated symbol method on the slave to map the access onto
the CFAM.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: tons of fixes, lots of love and care and time/
we need to split this patch ! ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...


Revision tags: v7.0.0, v6.2.0
# dbfd61ce 21-Sep-2021 Andrew Jeffery <andrew@aj.id.au>

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anywa

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for some fun with inter-processor buses. FSI allows a service
processor access to the internal busses of a host POWER processor to
perform configuration or debugging.

FSI has long existed in POWER processes and so comes with some baggage,
including how it has been integrated into the ASPEED SoC.

Working backwards from the POWER processor, the fundamental pieces of
interest for the implementation are:

1. The Common FRU Access Macro (CFAM), an address space containing
various "engines" that drive accesses on busses internal and external
to the POWER chip. Examples include the SBEFIFO and I2C masters. The
engines hang off of an internal Local Bus (LBUS) which is described
by the CFAM configuration block.

2. The FSI slave: The slave is the terminal point of the FSI bus for
FSI symbols addressed to it. Slaves can be cascaded off of one
another. The slave's configuration registers appear in address space
of the CFAM to which it is attached.

3. The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

4. The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

5. An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The implementation appears as following in the qemu device tree:

(qemu) info qtree
bus: main-system-bus
type System
...
dev: aspeed.apb2opb, id ""
gpio-out "sysbus-irq" 1
mmio 000000001e79b000/0000000000001000
bus: opb.1
type opb
dev: fsi.master, id ""
bus: fsi.bus.1
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.1
type lbus
dev: scratchpad, id ""
address = 0 (0x0)
bus: opb.0
type opb
dev: fsi.master, id ""
bus: fsi.bus.0
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.0
type lbus
dev: scratchpad, id ""
address = 0 (0x0)

The LBUS is modelled to maintain the qdev bus hierarchy and to take
advantage of the object model to automatically generate the CFAM
configuration block. The configuration block presents engines in the
order they are attached to the CFAM's LBUS. Engine implementations
should subclass the LBusDevice and set the 'config' member of
LBusDeviceClass to match the engine's type.

CFAM designs offer a lot of flexibility, for instance it is possible for
a CFAM to be simultaneously driven from multiple FSI links. The modeling
is not so complete; it's assumed that each CFAM is attached to a single
FSI slave (as a consequence the CFAM subclasses the FSI slave).

As for FSI, its symbols and wire-protocol are not modelled at all. This
is not necessary to get FSI off the ground thanks to the mapping of the
CFAM address space onto the OPB address space - the models follow this
directly and map the CFAM memory region into the OPB's memory region.
Future work includes supporting more advanced accesses that drive the
FSI master directly rather than indirectly via the CFAM mapping, which
will require implementing the FSI state machine and methods for each of
the FSI symbols on the slave. Further down the track we can also look at
supporting the bitbanged SoftFSI drivers in Linux by extending the FSI
slave model to resolve sequences of GPIO IRQs into FSI symbols, and
calling the associated symbol method on the slave to map the access onto
the CFAM.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: tons of fixes, lots of love and care and time/
we need to split this patch ! ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...


Revision tags: v6.1.0
# 9d287d6e 09-Dec-2020 Andrew Jeffery <andrew@aj.id.au>

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anywa

hw: Introduce models for IBM's Flexible Service Interface

Firstly, I'll split this patch up in the future, but wanted to get the
integrated setup sent out for any initial thoughts. Anyway:

Time for some fun with inter-processor buses. FSI allows a service
processor access to the internal busses of a host POWER processor to
perform configuration or debugging.

FSI has long existed in POWER processes and so comes with some baggage,
including how it has been integrated into the ASPEED SoC.

Working backwards from the POWER processor, the fundamental pieces of
interest for the implementation are:

1. The Common FRU Access Macro (CFAM), an address space containing
various "engines" that drive accesses on busses internal and external
to the POWER chip. Examples include the SBEFIFO and I2C masters. The
engines hang off of an internal Local Bus (LBUS) which is described
by the CFAM configuration block.

2. The FSI slave: The slave is the terminal point of the FSI bus for
FSI symbols addressed to it. Slaves can be cascaded off of one
another. The slave's configuration registers appear in address space
of the CFAM to which it is attached.

3. The FSI master: A controller in the platform service processor (e.g.
BMC) driving CFAM engine accesses into the POWER chip. At the
hardware level FSI is a bit-based protocol supporting synchronous and
DMA-driven accesses of engines in a CFAM.

4. The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

5. An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The implementation appears as following in the qemu device tree:

(qemu) info qtree
bus: main-system-bus
type System
...
dev: aspeed.apb2opb, id ""
gpio-out "sysbus-irq" 1
mmio 000000001e79b000/0000000000001000
bus: opb.1
type opb
dev: fsi.master, id ""
bus: fsi.bus.1
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.1
type lbus
dev: scratchpad, id ""
address = 0 (0x0)
bus: opb.0
type opb
dev: fsi.master, id ""
bus: fsi.bus.0
type fsi.bus
dev: cfam.config, id ""
dev: cfam, id ""
bus: lbus.0
type lbus
dev: scratchpad, id ""
address = 0 (0x0)

The LBUS is modelled to maintain the qdev bus hierarchy and to take
advantage of the object model to automatically generate the CFAM
configuration block. The configuration block presents engines in the
order they are attached to the CFAM's LBUS. Engine implementations
should subclass the LBusDevice and set the 'config' member of
LBusDeviceClass to match the engine's type.

CFAM designs offer a lot of flexibility, for instance it is possible for
a CFAM to be simultaneously driven from multiple FSI links. The modeling
is not so complete; it's assumed that each CFAM is attached to a single
FSI slave (as a consequence the CFAM subclasses the FSI slave).

As for FSI, its symbols and wire-protocol are not modelled at all. This
is not necessary to get FSI off the ground thanks to the mapping of the
CFAM address space onto the OPB address space - the models follow this
directly and map the CFAM memory region into the OPB's memory region.
Future work includes supporting more advanced accesses that drive the
FSI master directly rather than indirectly via the CFAM mapping, which
will require implementing the FSI state machine and methods for each of
the FSI symbols on the slave. Further down the track we can also look at
supporting the bitbanged SoftFSI drivers in Linux by extending the FSI
slave model to resolve sequences of GPIO IRQs into FSI symbols, and
calling the associated symbol method on the slave to map the access onto
the CFAM.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: tons of fixes, lots of love and care and time/
we need to split this patch ! ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

show more ...