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c: df2634f
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Sebastian Andrzej Siewior authored and Thomas Gleixner committed Feb 23, 2011
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: da6b737b9ab768dd06bb4b0395131d10e524cf83
refs/heads/master: df2634f43f5106947f3735a0b61a6527a4b278cd
93 changes: 93 additions & 0 deletions trunk/Documentation/devicetree/bindings/i2c/ce4100-i2c.txt
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CE4100 I2C
----------

CE4100 has one PCI device which is described as the I2C-Controller. This
PCI device has three PCI-bars, each bar contains a complete I2C
controller. So we have a total of three independent I2C-Controllers
which share only an interrupt line.
The driver is probed via the PCI-ID and is gathering the information of
attached devices from the devices tree.
Grant Likely recommended to use the ranges property to map the PCI-Bar
number to its physical address and to use this to find the child nodes
of the specific I2C controller. This were his exact words:

Here's where the magic happens. Each entry in
ranges describes how the parent pci address space
(middle group of 3) is translated to the local
address space (first group of 2) and the size of
each range (last cell). In this particular case,
the first cell of the local address is chosen to be
1:1 mapped to the BARs, and the second is the
offset from be base of the BAR (which would be
non-zero if you had 2 or more devices mapped off
the same BAR)

ranges allows the address mapping to be described
in a way that the OS can interpret without
requiring custom device driver code.

This is an example which is used on FalconFalls:
------------------------------------------------
i2c-controller@b,2 {
#address-cells = <2>;
#size-cells = <1>;
compatible = "pci8086,2e68.2",
"pci8086,2e68",
"pciclass,ff0000",
"pciclass,ff00";

reg = <0x15a00 0x0 0x0 0x0 0x0>;
interrupts = <16 1>;

/* as described by Grant, the first number in the group of
* three is the bar number followed by the 64bit bar address
* followed by size of the mapping. The bar address
* requires also a valid translation in parents ranges
* property.
*/
ranges = <0 0 0x02000000 0 0xdffe0500 0x100
1 0 0x02000000 0 0xdffe0600 0x100
2 0 0x02000000 0 0xdffe0700 0x100>;

i2c@0 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "intel,ce4100-i2c-controller";

/* The first number in the reg property is the
* number of the bar
*/
reg = <0 0 0x100>;

/* This I2C controller has no devices */
};

i2c@1 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "intel,ce4100-i2c-controller";
reg = <1 0 0x100>;

/* This I2C controller has one gpio controller */
gpio@26 {
#gpio-cells = <2>;
compatible = "ti,pcf8575";
reg = <0x26>;
gpio-controller;
};
};

i2c@2 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "intel,ce4100-i2c-controller";
reg = <2 0 0x100>;

gpio@26 {
#gpio-cells = <2>;
compatible = "ti,pcf8575";
reg = <0x26>;
gpio-controller;
};
};
};
38 changes: 38 additions & 0 deletions trunk/Documentation/devicetree/bindings/x86/ce4100.txt
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CE4100 Device Tree Bindings
---------------------------

The CE4100 SoC uses for in core peripherals the following compatible
format: <vendor>,<chip>-<device>.
Many of the "generic" devices like HPET or IO APIC have the ce4100
name in their compatible property because they first appeared in this
SoC.

The CPU node
------------
cpu@0 {
device_type = "cpu";
compatible = "intel,ce4100";
reg = <0>;
lapic = <&lapic0>;
};

The reg property describes the CPU number. The lapic property points to
the local APIC timer.

The SoC node
------------

This node describes the in-core peripherals. Required property:
compatible = "intel,ce4100-cp";

The PCI node
------------
This node describes the PCI bus on the SoC. Its property should be
compatible = "intel,ce4100-pci", "pci";

If the OS is using the IO-APIC for interrupt routing then the reported
interrupt numbers for devices is no longer true. In order to obtain the
correct interrupt number, the child node which represents the device has
to contain the interrupt property. Besides the interrupt property it has
to contain at least the reg property containing the PCI bus address and
compatible property according to "PCI Bus Binding Revision 2.1".
29 changes: 29 additions & 0 deletions trunk/Documentation/devicetree/bindings/x86/interrupt.txt
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Interrupt chips
---------------

* Intel I/O Advanced Programmable Interrupt Controller (IO APIC)

Required properties:
--------------------
compatible = "intel,ce4100-ioapic";
#interrupt-cells = <2>;

Device's interrupt property:

interrupts = <P S>;

The first number (P) represents the interrupt pin which is wired to the
IO APIC. The second number (S) represents the sense of interrupt which
should be configured and can be one of:
0 - Edge Rising
1 - Level Low
2 - Level High
3 - Edge Falling

* Local APIC
Required property:

compatible = "intel,ce4100-lapic";

This node is currently unused by Linux as the address of the local APIC
read from a MSR.
6 changes: 6 additions & 0 deletions trunk/Documentation/devicetree/bindings/x86/timer.txt
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Timers
------

* High Precision Event Timer (HPET)
Required property:
compatible = "intel,ce4100-hpet";
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