From 59dc33252ee777e02332774fbdf3381b1d5d5f5d Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 24 Aug 2021 16:43:55 +0200 Subject: [PATCH] PCI: VMD: ACPI: Make ACPI companion lookup work for VMD bus On some systems, in order to get to the deepest low-power state of the platform (which may be necessary to save significant enough amounts of energy while suspended to idle. for example), devices on the PCI bus exposed by the VMD driver need to be power-managed via ACPI. However, the layout of the ACPI namespace below the VMD controller device object does not reflect the layout of the PCI bus under the VMD host bridge, so in order to identify the ACPI companion objects for the devices on that bus, it is necessary to use a special _ADR encoding on the ACPI side. In other words, acpi_pci_find_companion() does not work for these devices, so it needs to be amended with a special lookup logic specific to the VMD bus. Address this issue by allowing the VMD driver to temporarily install an ACPI companion lookup hook containing the code matching the devices on the VMD PCI bus with the corresponding objects in the ACPI namespace. Signed-off-by: Rafael J. Wysocki Acked-by: Jon Derrick --- drivers/pci/controller/vmd.c | 55 +++++++++++++++++++++++++++ drivers/pci/host-bridge.c | 1 + drivers/pci/pci-acpi.c | 74 ++++++++++++++++++++++++++++++++++++ include/linux/pci-acpi.h | 3 ++ 4 files changed, 133 insertions(+) diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index e3fcdfec58b332..a5987e52700e3a 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -447,6 +448,56 @@ static struct pci_ops vmd_ops = { .write = vmd_pci_write, }; +#ifdef CONFIG_ACPI +static struct acpi_device *vmd_acpi_find_companion(struct pci_dev *pci_dev) +{ + struct pci_host_bridge *bridge; + u32 busnr, addr; + + if (pci_dev->bus->ops != &vmd_ops) + return NULL; + + bridge = pci_find_host_bridge(pci_dev->bus); + busnr = pci_dev->bus->number - bridge->bus->number; + /* + * The address computation below is only applicable to relative bus + * numbers below 32. + */ + if (busnr > 31) + return NULL; + + addr = (busnr << 24) | ((u32)pci_dev->devfn << 16) | 0x8000FFFFU; + + dev_dbg(&pci_dev->dev, "Looking for ACPI companion (address 0x%x)\n", + addr); + + return acpi_find_child_device(ACPI_COMPANION(bridge->dev.parent), addr, + false); +} + +static bool hook_installed; + +static void vmd_acpi_begin(void) +{ + if (pci_acpi_set_companion_lookup_hook(vmd_acpi_find_companion)) + return; + + hook_installed = true; +} + +static void vmd_acpi_end(void) +{ + if (!hook_installed) + return; + + pci_acpi_clear_companion_lookup_hook(); + hook_installed = false; +} +#else +static inline void vmd_acpi_begin(void) { } +static inline void vmd_acpi_end(void) { } +#endif /* CONFIG_ACPI */ + static void vmd_attach_resources(struct vmd_dev *vmd) { vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[1]; @@ -747,6 +798,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) if (vmd->irq_domain) dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain); + vmd_acpi_begin(); + pci_scan_child_bus(vmd->bus); pci_assign_unassigned_bus_resources(vmd->bus); @@ -760,6 +813,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) pci_bus_add_devices(vmd->bus); + vmd_acpi_end(); + WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj, "domain"), "Can't create symlink to domain\n"); return 0; diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c index e01d53f5b32f6f..afa50b446567f7 100644 --- a/drivers/pci/host-bridge.c +++ b/drivers/pci/host-bridge.c @@ -23,6 +23,7 @@ struct pci_host_bridge *pci_find_host_bridge(struct pci_bus *bus) return to_pci_host_bridge(root_bus->bridge); } +EXPORT_SYMBOL_GPL(pci_find_host_bridge); struct device *pci_get_host_bridge_device(struct pci_dev *dev) { diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index 36bc23e2175927..825988a5c074ce 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "pci.h" /* @@ -1159,6 +1160,69 @@ void acpi_pci_remove_bus(struct pci_bus *bus) } /* ACPI bus type */ + + +static DECLARE_RWSEM(pci_acpi_companion_lookup_sem); +static struct acpi_device *(*pci_acpi_find_companion_hook)(struct pci_dev *); + +/** + * pci_acpi_set_companion_lookup_hook - Set ACPI companion lookup callback. + * @func: ACPI companion lookup callback pointer or NULL. + * + * Set a special ACPI companion lookup callback for PCI devices whose companion + * objects in the ACPI namespace have _ADR with non-standard bus-device-function + * encodings. + * + * Return 0 on success or a negative error code on failure (in which case no + * changes are made). + * + * The caller is responsible for the appropriate ordering of the invocations of + * this function with respect to the enumeration of the PCI devices needing the + * callback installed by it. + */ +int pci_acpi_set_companion_lookup_hook(struct acpi_device *(*func)(struct pci_dev *)) +{ + int ret; + + if (!func) + return -EINVAL; + + down_write(&pci_acpi_companion_lookup_sem); + + if (pci_acpi_find_companion_hook) { + ret = -EBUSY; + } else { + pci_acpi_find_companion_hook = func; + ret = 0; + } + + up_write(&pci_acpi_companion_lookup_sem); + + return ret; +} +EXPORT_SYMBOL_GPL(pci_acpi_set_companion_lookup_hook); + +/** + * pci_acpi_clear_companion_lookup_hook - Clear ACPI companion lookup callback. + * + * Clear the special ACPI companion lookup callback previously set by + * pci_acpi_set_companion_lookup_hook(). Block until the last running instance + * of the callback returns before clearing it. + * + * The caller is responsible for the appropriate ordering of the invocations of + * this function with respect to the enumeration of the PCI devices needing the + * callback cleared by it. + */ +void pci_acpi_clear_companion_lookup_hook(void) +{ + down_write(&pci_acpi_companion_lookup_sem); + + pci_acpi_find_companion_hook = NULL; + + up_write(&pci_acpi_companion_lookup_sem); +} +EXPORT_SYMBOL_GPL(pci_acpi_clear_companion_lookup_hook); + static struct acpi_device *acpi_pci_find_companion(struct device *dev) { struct pci_dev *pci_dev = to_pci_dev(dev); @@ -1166,6 +1230,16 @@ static struct acpi_device *acpi_pci_find_companion(struct device *dev) bool check_children; u64 addr; + down_read(&pci_acpi_companion_lookup_sem); + + adev = pci_acpi_find_companion_hook ? + pci_acpi_find_companion_hook(pci_dev) : NULL; + + up_read(&pci_acpi_companion_lookup_sem); + + if (adev) + return adev; + check_children = pci_is_bridge(pci_dev); /* Please ref to ACPI spec for the syntax of _ADR */ addr = (PCI_SLOT(pci_dev->devfn) << 16) | PCI_FUNC(pci_dev->devfn); diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h index 5ba475ca907825..f16de399d2de20 100644 --- a/include/linux/pci-acpi.h +++ b/include/linux/pci-acpi.h @@ -122,6 +122,9 @@ static inline void pci_acpi_add_edr_notifier(struct pci_dev *pdev) { } static inline void pci_acpi_remove_edr_notifier(struct pci_dev *pdev) { } #endif /* CONFIG_PCIE_EDR */ +int pci_acpi_set_companion_lookup_hook(struct acpi_device *(*func)(struct pci_dev *)); +void pci_acpi_clear_companion_lookup_hook(void); + #else /* CONFIG_ACPI */ static inline void acpi_pci_add_bus(struct pci_bus *bus) { } static inline void acpi_pci_remove_bus(struct pci_bus *bus) { }