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path: root/drivers/pci/irq.c
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-rw-r--r--drivers/pci/irq.c204
1 files changed, 204 insertions, 0 deletions
diff --git a/drivers/pci/irq.c b/drivers/pci/irq.c
index 0050e8f6814e..4555630be9ec 100644
--- a/drivers/pci/irq.c
+++ b/drivers/pci/irq.c
@@ -8,9 +8,13 @@
#include <linux/device.h>
#include <linux/kernel.h>
+#include <linux/errno.h>
#include <linux/export.h>
+#include <linux/interrupt.h>
#include <linux/pci.h>
+#include "pci.h"
+
/**
* pci_request_irq - allocate an interrupt line for a PCI device
* @dev: PCI device to operate on
@@ -74,3 +78,203 @@ void pci_free_irq(struct pci_dev *dev, unsigned int nr, void *dev_id)
kfree(free_irq(pci_irq_vector(dev, nr), dev_id));
}
EXPORT_SYMBOL(pci_free_irq);
+
+/**
+ * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge
+ * @dev: the PCI device
+ * @pin: the INTx pin (1=INTA, 2=INTB, 3=INTC, 4=INTD)
+ *
+ * Perform INTx swizzling for a device behind one level of bridge. This is
+ * required by section 9.1 of the PCI-to-PCI bridge specification for devices
+ * behind bridges on add-in cards. For devices with ARI enabled, the slot
+ * number is always 0 (see the Implementation Note in section 2.2.8.1 of
+ * the PCI Express Base Specification, Revision 2.1)
+ */
+u8 pci_swizzle_interrupt_pin(const struct pci_dev *dev, u8 pin)
+{
+ int slot;
+
+ if (pci_ari_enabled(dev->bus))
+ slot = 0;
+ else
+ slot = PCI_SLOT(dev->devfn);
+
+ return (((pin - 1) + slot) % 4) + 1;
+}
+
+int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge)
+{
+ u8 pin;
+
+ pin = dev->pin;
+ if (!pin)
+ return -1;
+
+ while (!pci_is_root_bus(dev->bus)) {
+ pin = pci_swizzle_interrupt_pin(dev, pin);
+ dev = dev->bus->self;
+ }
+ *bridge = dev;
+ return pin;
+}
+
+/**
+ * pci_common_swizzle - swizzle INTx all the way to root bridge
+ * @dev: the PCI device
+ * @pinp: pointer to the INTx pin value (1=INTA, 2=INTB, 3=INTD, 4=INTD)
+ *
+ * Perform INTx swizzling for a device. This traverses through all PCI-to-PCI
+ * bridges all the way up to a PCI root bus.
+ */
+u8 pci_common_swizzle(struct pci_dev *dev, u8 *pinp)
+{
+ u8 pin = *pinp;
+
+ while (!pci_is_root_bus(dev->bus)) {
+ pin = pci_swizzle_interrupt_pin(dev, pin);
+ dev = dev->bus->self;
+ }
+ *pinp = pin;
+ return PCI_SLOT(dev->devfn);
+}
+EXPORT_SYMBOL_GPL(pci_common_swizzle);
+
+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 because 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);
+}
+
+static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask)
+{
+ struct pci_bus *bus = dev->bus;
+ bool mask_updated = true;
+ u32 cmd_status_dword;
+ u16 origcmd, newcmd;
+ unsigned long flags;
+ bool irq_pending;
+
+ /*
+ * We do a single dword read to retrieve both command and status.
+ * Document assumptions that make this possible.
+ */
+ BUILD_BUG_ON(PCI_COMMAND % 4);
+ BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS);
+
+ raw_spin_lock_irqsave(&pci_lock, flags);
+
+ bus->ops->read(bus, dev->devfn, PCI_COMMAND, 4, &cmd_status_dword);
+
+ irq_pending = (cmd_status_dword >> 16) & PCI_STATUS_INTERRUPT;
+
+ /*
+ * Check interrupt status register to see whether our device
+ * triggered the interrupt (when masking) or the next IRQ is
+ * already pending (when unmasking).
+ */
+ if (mask != irq_pending) {
+ mask_updated = false;
+ goto done;
+ }
+
+ origcmd = cmd_status_dword;
+ newcmd = origcmd & ~PCI_COMMAND_INTX_DISABLE;
+ if (mask)
+ newcmd |= PCI_COMMAND_INTX_DISABLE;
+ if (newcmd != origcmd)
+ bus->ops->write(bus, dev->devfn, PCI_COMMAND, 2, newcmd);
+
+done:
+ raw_spin_unlock_irqrestore(&pci_lock, flags);
+
+ return mask_updated;
+}
+
+/**
+ * pci_check_and_mask_intx - mask INTx on pending interrupt
+ * @dev: the PCI device to operate on
+ *
+ * Check if the device dev has its INTx line asserted, mask it and return
+ * true in that case. False is returned if no interrupt was pending.
+ */
+bool pci_check_and_mask_intx(struct pci_dev *dev)
+{
+ return pci_check_and_set_intx_mask(dev, true);
+}
+EXPORT_SYMBOL_GPL(pci_check_and_mask_intx);
+
+/**
+ * pci_check_and_unmask_intx - unmask INTx if no interrupt is pending
+ * @dev: the PCI device to operate on
+ *
+ * Check if the device dev has its INTx line asserted, unmask it if not and
+ * return true. False is returned and the mask remains active if there was
+ * still an interrupt pending.
+ */
+bool pci_check_and_unmask_intx(struct pci_dev *dev)
+{
+ return pci_check_and_set_intx_mask(dev, false);
+}
+EXPORT_SYMBOL_GPL(pci_check_and_unmask_intx);
+
+/**
+ * pcibios_penalize_isa_irq - penalize an ISA IRQ
+ * @irq: ISA IRQ to penalize
+ * @active: IRQ active or not
+ *
+ * Permits the platform to provide architecture-specific functionality when
+ * penalizing ISA IRQs. This is the default implementation. Architecture
+ * implementations can override this.
+ */
+void __weak pcibios_penalize_isa_irq(int irq, int active) {}
+
+int __weak pcibios_alloc_irq(struct pci_dev *dev)
+{
+ return 0;
+}
+
+void __weak pcibios_free_irq(struct pci_dev *dev)
+{
+}