From 0d58e6c1b19b30623b5f0a053818bd2c32d61166 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Tue, 15 Aug 2017 12:02:17 -0700 Subject: [PATCH] PCI: Add pci_irqd_intx_xlate() Legacy PCI INTx interrupts are represented in the PCI_INTERRUPT_PIN register using the range 1-4, which matches our enum pci_interrupt_pin. This is however not ideal for an IRQ domain, where with 4 interrupts we would ideally have a domain of size 4 & hwirq numbers in the range 0-3. Different PCI host controller drivers have handled this in different ways. Of those under drivers/pci/ which register an INTx IRQ domain, we have: - pcie-altera uses the range 1-4 in device trees and an IRQ domain of size 5 to cover that range, with entry 0 wasted. - pcie-xilinx & pcie-xilinx-nwl use the range 1-4 in device trees but register an IRQ domain of size 4, which doesn't cover the hwirq=4/INTD case leading to that interrupt being broken. - pci-ftpci100 & pci-aardvark use the range 0-3 in both device trees & as hwirq numbering in the driver & IRQ domain. In order to introduce some level of consistency in at least the hwirq numbering used by the drivers & IRQ domains, this patch introduces a new pci_irqd_intx_xlate() helper function which drivers using the 1-4 range in device trees can assign as the xlate callback for their INTx IRQ domain. This translates the 1-4 range into a 0-3 range, allowing us to use an IRQ domain of size 4 & avoid a wasted entry. Further patches will make use of this in drivers to allow them to use an IRQ domain of size 4 for legacy INTx interrupts without breaking INTD. Signed-off-by: Paul Burton Signed-off-by: Bjorn Helgaas --- include/linux/pci.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/include/linux/pci.h b/include/linux/pci.h index bb9c367c85f0..bbc2a991b63f 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1416,6 +1416,38 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs, NULL); } +/** + * pci_irqd_intx_xlate() - Translate PCI INTx value to an IRQ domain hwirq + * @d: the INTx IRQ domain + * @node: the DT node for the device whose interrupt we're translating + * @intspec: the interrupt specifier data from the DT + * @intsize: the number of entries in @intspec + * @out_hwirq: pointer at which to write the hwirq number + * @out_type: pointer at which to write the interrupt type + * + * Translate a PCI INTx interrupt number from device tree in the range 1-4, as + * stored in the standard PCI_INTERRUPT_PIN register, to a value in the range + * 0-3 suitable for use in a 4 entry IRQ domain. That is, subtract one from the + * INTx value to obtain the hwirq number. + * + * Returns 0 on success, or -EINVAL if the interrupt specifier is out of range. + */ +static inline int pci_irqd_intx_xlate(struct irq_domain *d, + struct device_node *node, + const u32 *intspec, + unsigned int intsize, + unsigned long *out_hwirq, + unsigned int *out_type) +{ + const u32 intx = intspec[0]; + + if (intx < PCI_INTERRUPT_INTA || intx > PCI_INTERRUPT_INTD) + return -EINVAL; + + *out_hwirq = intx - PCI_INTERRUPT_INTA; + return 0; +} + #ifdef CONFIG_PCIEPORTBUS extern bool pcie_ports_disabled; extern bool pcie_ports_auto; -- 2.11.0