diff options
Diffstat (limited to 'drivers/pci/setup-irq.c')
| -rw-r--r-- | drivers/pci/setup-irq.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c new file mode 100644 index 000000000..712949475 --- /dev/null +++ b/drivers/pci/setup-irq.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Support routines for initializing a PCI subsystem + * + * Extruded from code written by + * Dave Rusling (david.rusling@reo.mts.dec.com) + * David Mosberger (davidm@cs.arizona.edu) + * David Miller (davem@redhat.com) + */ + + +#include <linux/kernel.h> +#include <linux/pci.h> +#include <linux/errno.h> +#include <linux/ioport.h> +#include <linux/cache.h> +#include "pci.h" + +void pci_assign_irq(struct pci_dev *dev) +{ + u8 pin; + u8 slot = -1; + int irq = 0; + struct pci_host_bridge *hbrg = pci_find_host_bridge(dev->bus); + + if (!(hbrg->map_irq)) { + pci_dbg(dev, "runtime IRQ mapping not provided by arch\n"); + return; + } + + /* If this device is not on the primary bus, we need to figure out + which interrupt pin it will come in on. We know which slot it + will come in on 'cos that slot is where the bridge is. Each + time the interrupt line passes through a PCI-PCI bridge we must + apply the swizzle function. */ + + pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin); + /* Cope with illegal. */ + if (pin > 4) + pin = 1; + + if (pin) { + /* Follow the chain of bridges, swizzling as we go. */ + if (hbrg->swizzle_irq) + slot = (*(hbrg->swizzle_irq))(dev, &pin); + + /* + * If a swizzling function is not used map_irq must + * ignore slot + */ + irq = (*(hbrg->map_irq))(dev, slot, pin); + if (irq == -1) + irq = 0; + } + dev->irq = irq; + + pci_dbg(dev, "assign IRQ: got %d\n", dev->irq); + + /* Always tell the device, so the driver knows what is + the real IRQ to use; the device does not use it. */ + pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq); +} |