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author | Timur Tabi <timur@freescale.com> | 2011-09-23 21:41:35 +0400 |
---|---|---|
committer | Kumar Gala <galak@kernel.crashing.org> | 2011-10-14 11:54:29 +0400 |
commit | 2bcd1c0cfcf53a384159c272c972645e7e822140 (patch) | |
tree | 221e336531b92f2eef53cd48a1c1ad217ccf894b /Documentation/devicetree/bindings/powerpc/fsl | |
parent | 45116806139743cf35baa01a584e5972e5d833f6 (diff) | |
download | linux-2bcd1c0cfcf53a384159c272c972645e7e822140.tar.xz |
powerpc/fsl_msi: add support for "msi-address-64" property
Add support for the msi-address-64 property of a PCI node. This property
specifies the PCI address of MSIIR (message signaled interrupt index
register).
In commit 3da34aae ("powerpc/fsl: Support unique MSI addresses per PCIe Root
Complex"), the msi_addr_hi/msi_addr_lo fields of struct fsl_msi were redefined
from an actual address to just an offset, but the fields were not renamed
accordingly. These fields are replace with a single field, msiir_offset,
to reflect the new meaning.
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Diffstat (limited to 'Documentation/devicetree/bindings/powerpc/fsl')
-rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt b/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt index 70558c3f3682..5d586e1ccaf5 100644 --- a/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt +++ b/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt @@ -25,6 +25,16 @@ Required properties: are routed to IPIC, and for 85xx/86xx cpu the interrupts are routed to MPIC. +Optional properties: +- msi-address-64: 64-bit PCI address of the MSIIR register. The MSIIR register + is used for MSI messaging. The address of MSIIR in PCI address space is + the MSI message address. + + This property may be used in virtualized environments where the hypervisor + has created an alternate mapping for the MSIR block. See below for an + explanation. + + Example: msi@41600 { compatible = "fsl,mpc8610-msi", "fsl,mpic-msi"; @@ -41,3 +51,35 @@ Example: 0xe7 0>; interrupt-parent = <&mpic>; }; + +The Freescale hypervisor and msi-address-64 +------------------------------------------- +Normally, PCI devices have access to all of CCSR via an ATMU mapping. The +Freescale MSI driver calculates the address of MSIIR (in the MSI register +block) and sets that address as the MSI message address. + +In a virtualized environment, the hypervisor may need to create an IOMMU +mapping for MSIIR. The Freescale ePAPR hypervisor has this requirement +because of hardware limitations of the Peripheral Access Management Unit +(PAMU), which is currently the only IOMMU that the hypervisor supports. +The ATMU is programmed with the guest physical address, and the PAMU +intercepts transactions and reroutes them to the true physical address. + +In the PAMU, each PCI controller is given only one primary window. The +PAMU restricts DMA operations so that they can only occur within a window. +Because PCI devices must be able to DMA to memory, the primary window must +be used to cover all of the guest's memory space. + +PAMU primary windows can be divided into 256 subwindows, and each +subwindow can have its own address mapping ("guest physical" to "true +physical"). However, each subwindow has to have the same alignment, which +means they cannot be located at just any address. Because of these +restrictions, it is usually impossible to create a 4KB subwindow that +covers MSIIR where it's normally located. + +Therefore, the hypervisor has to create a subwindow inside the same +primary window used for memory, but mapped to the MSIR block (where MSIIR +lives). The first subwindow after the end of guest memory is used for +this. The address specified in the msi-address-64 property is the PCI +address of MSIIR. The hypervisor configures the PAMU to map that address to +the true physical address of MSIIR. |