xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

PCI/MSI: Add pci_msi_vec_count()

Browse Source 
Device drivers can use this interface to obtain the maximum number of MSI
interrupts the device supports and use that number, e.g., in a subsequent
call to pci_enable_msi_block().

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Alexander Gordeev
2013-12-30 08:28:13 +01:00
committed by Bjorn Helgaas
parent 52179dc9ed
commit d1ac1d2622
3 changed files with 54 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
drivers/pci/msi.c
View File

@@ -842,6 +842,31 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type)
return 0;
}
/**
* pci_msi_vec_count - Return the number of MSI vectors a device can send
* @dev: device to report about
*
* This function returns the number of MSI vectors a device requested via
* Multiple Message Capable register. It returns a negative errno if the
* device is not capable sending MSI interrupts. Otherwise, the call succeeds
* and returns a power of two, up to a maximum of 2^5 (32), according to the
* MSI specification.
**/
int pci_msi_vec_count(struct pci_dev *dev)
{
int ret;
u16 msgctl;
if (!dev->msi_cap)
return -EINVAL;
pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
return ret;
}
EXPORT_SYMBOL(pci_msi_vec_count);
/**
* pci_enable_msi_block - configure device's MSI capability structure
* @dev: device to configure
@@ -858,13 +883,13 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type)
int pci_enable_msi_block(struct pci_dev *dev, int nvec)
{
int status, maxvec;
u16 msgctl;
if (!dev->msi_cap || dev->current_state != PCI_D0)
if (dev->current_state != PCI_D0)
return -EINVAL;
pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
maxvec = pci_msi_vec_count(dev);
if (maxvec < 0)
return maxvec;
if (nvec > maxvec)
return maxvec;
@@ -889,13 +914,13 @@ EXPORT_SYMBOL(pci_enable_msi_block);
int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec)
{
int ret, nvec;
u16 msgctl;
if (!dev->msi_cap || dev->current_state != PCI_D0)
if (dev->current_state != PCI_D0)
return -EINVAL;
pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
ret = pci_msi_vec_count(dev);
if (ret < 0)
return ret;
if (maxvec)
*maxvec = ret;