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author | Ingo Molnar <mingo@kernel.org> | 2021-03-18 15:27:03 +0100 |
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committer | Ingo Molnar <mingo@kernel.org> | 2021-03-18 15:27:03 +0100 |
commit | 14ff3ed86e2c1700345f411b90a78f62867f217e (patch) | |
tree | 0eec583be82296fa6359edb59f2921095eef0dc2 /drivers/usb/core | |
parent | 81519f778830d1ab02274eeaaeab6797fdc4ec52 (diff) | |
parent | 1e28eed17697bcf343c6743f0028cc3b5dd88bf0 (diff) | |
download | linux-14ff3ed86e2c1700345f411b90a78f62867f217e.tar.gz |
Merge tag 'v5.12-rc3' into x86/cleanups, to refresh the tree
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/usb/core')
-rw-r--r-- | drivers/usb/core/usb.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index 8f07b0516100..a566bb494e24 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -748,6 +748,38 @@ void usb_put_intf(struct usb_interface *intf) } EXPORT_SYMBOL_GPL(usb_put_intf); +/** + * usb_intf_get_dma_device - acquire a reference on the usb interface's DMA endpoint + * @intf: the usb interface + * + * While a USB device cannot perform DMA operations by itself, many USB + * controllers can. A call to usb_intf_get_dma_device() returns the DMA endpoint + * for the given USB interface, if any. The returned device structure must be + * released with put_device(). + * + * See also usb_get_dma_device(). + * + * Returns: A reference to the usb interface's DMA endpoint; or NULL if none + * exists. + */ +struct device *usb_intf_get_dma_device(struct usb_interface *intf) +{ + struct usb_device *udev = interface_to_usbdev(intf); + struct device *dmadev; + + if (!udev->bus) + return NULL; + + dmadev = get_device(udev->bus->sysdev); + if (!dmadev || !dmadev->dma_mask) { + put_device(dmadev); + return NULL; + } + + return dmadev; +} +EXPORT_SYMBOL_GPL(usb_intf_get_dma_device); + /* USB device locking * * USB devices and interfaces are locked using the semaphore in their |