Platforms supporting the DDW option starting with LoPAR level 2.7 implement
ibm,ddw-extensions. The first extension available (index 2) carries the
token for ibm,reset-pe-dma-windows rtas call, which is used to restore
the default DMA window for a device, if it has been deleted.
It does so by resetting the TCE table allocation for the PE to it's
boot time value, available in "ibm,dma-window" device tree node.
Signed-off-by: Leonardo Bras <leobra...@gmail.com>
---
arch/powerpc/platforms/pseries/iommu.c | 33 ++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index e5a617738c8b..5e1fbc176a37 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1012,6 +1012,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
return max_addr;
}
+/*
+ * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
+ * ibm,ddw-extensions, which carries the rtas token for
+ * ibm,reset-pe-dma-windows.
+ * That rtas-call can be used to restore the default DMA window for the device.
+ */
+static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
+{
+ int ret;
+ u32 cfg_addr, ddw_ext[3];
+ u64 buid;
+ struct device_node *dn;
+ struct pci_dn *pdn;
+
+ ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
+ &ddw_ext[0], 3);
+ if (ret)
+ return;
+
+ dn = pci_device_to_OF_node(dev);
+ pdn = PCI_DN(dn);
+ buid = pdn->phb->buid;
+ cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
+
+ ret = rtas_call(ddw_ext[1], 3, 1, NULL, cfg_addr,
+ BUID_HI(buid), BUID_LO(buid));
+ if (ret)
+ dev_info(&dev->dev,
+ "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
+ ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),
+ ret);
+}
+
/*
* If the PE supports dynamic dma windows, and there is space for a table
* that can map all pages in a linear offset, then setup such a table,
--
2.25.4
