Some chipsets use the function 0 for DMA on other functions of a
multifunctional device. One of the example is Intel EG20T PCH. This is also
applicable to Lynxpoint PCH when LPSS devices are switched to PCI mode.
This patch exports a useful helper to get a device of the DMA. This device is
needed to request a DMA channel from a proper controller.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/pci/quirks.c | 2 +-
include/linux/pci.h | 9 +++++++++
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 80c2d01..8352e5b 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3517,7 +3517,7 @@ static struct pci_dev *pci_func_0_dma_source(struct pci_dev *dev)
if (!PCI_FUNC(dev->devfn))
return pci_dev_get(dev);
- return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
+ return pci_get_dma_device(dev);
}
static const struct pci_dev_dma_source {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 61978a4..86caab7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1575,6 +1575,15 @@ static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev,
static inline void pci_dev_specific_enable_acs(struct pci_dev *dev) { }
#endif
+/*
+ * Some chipsets use the function 0 for DMA on other functions of a
+ * multifunctional device.
+ */
+static inline struct pci_dev *pci_get_dma_device(struct pci_dev *dev)
+{
+ return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
+}
+
void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
void pcim_iounmap(struct pci_dev *pdev, void __iomem *addr);
void __iomem * const *pcim_iomap_table(struct pci_dev *pdev);
--
2.0.1
--
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