Man page 9 : pci_enable_msi_block

pci_enable_msi_block - configure deviceAqs MSI capability structure

int pci_enable_msi_block(struct pci_dev *  dev , unsigned int  nvec );

dev
    device to configure

nvec
    number of interrupts to configure

Allocate IRQs for a device with the MSI capability. This function returns a negative errno if an error occurs. If it is unable to allocate the number of interrupts requested, it returns the number of interrupts it might be able to allocate. If it successfully allocates at least the number of interrupts requested, it returns 0 and updates the devAqs irq member to the lowest new interrupt number; the other interrupt numbers allocated to this device are consecutive.