Merge tag 'pci-v4.1-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

[sfrench/cifs-2.6.git] / drivers / pci / pci-acpi.c

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index c93fbe76d281c4b4822ceddae79feab984cfb576..6f6f175f51f78003524e96c046fb58b7298407ad 100644 (file)
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -18,6 +18,15 @@
 #include <linux/pm_qos.h>
 #include "pci.h"
 
+/*
+ * The UUID is defined in the PCI Firmware Specification available here:
+ * https://www.pcisig.com/members/downloads/pcifw_r3_1_13Dec10.pdf
+ */
+const u8 pci_acpi_dsm_uuid[] = {
+       0xd0, 0x37, 0xc9, 0xe5, 0x53, 0x35, 0x7a, 0x4d,
+       0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
+};
+
 phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
 {
        acpi_status status = AE_NOT_EXIST;
@@ -531,11 +540,32 @@ static struct pci_platform_pm_ops acpi_pci_platform_pm = {
 
 void acpi_pci_add_bus(struct pci_bus *bus)
 {
+       union acpi_object *obj;
+       struct pci_host_bridge *bridge;
+
        if (acpi_pci_disabled || !bus->bridge)
                return;
 
        acpi_pci_slot_enumerate(bus);
        acpiphp_enumerate_slots(bus);
+
+       /*
+        * For a host bridge, check its _DSM for function 8 and if
+        * that is available, mark it in pci_host_bridge.
+        */
+       if (!pci_is_root_bus(bus))
+               return;
+
+       obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), pci_acpi_dsm_uuid, 3,
+                               RESET_DELAY_DSM, NULL);
+       if (!obj)
+               return;
+
+       if (obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 1) {
+               bridge = pci_find_host_bridge(bus);
+               bridge->ignore_reset_delay = 1;
+       }
+       ACPI_FREE(obj);
 }
 
 void acpi_pci_remove_bus(struct pci_bus *bus)
@@ -561,6 +591,57 @@ static struct acpi_device *acpi_pci_find_companion(struct device *dev)
                                      check_children);
 }
 
+/**
+ * pci_acpi_optimize_delay - optimize PCI D3 and D3cold delay from ACPI
+ * @pdev: the PCI device whose delay is to be updated
+ * @adev: the companion ACPI device of this PCI device
+ *
+ * Update the d3_delay and d3cold_delay of a PCI device from the ACPI _DSM
+ * control method of either the device itself or the PCI host bridge.
+ *
+ * Function 8, "Reset Delay," applies to the entire hierarchy below a PCI
+ * host bridge.  If it returns one, the OS may assume that all devices in
+ * the hierarchy have already completed power-on reset delays.
+ *
+ * Function 9, "Device Readiness Durations," applies only to the object
+ * where it is located.  It returns delay durations required after various
+ * events if the device requires less time than the spec requires.  Delays
+ * from this function take precedence over the Reset Delay function.
+ *
+ * These _DSM functions are defined by the draft ECN of January 28, 2014,
+ * titled "ACPI additions for FW latency optimizations."
+ */
+static void pci_acpi_optimize_delay(struct pci_dev *pdev,
+                                   acpi_handle handle)
+{
+       struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
+       int value;
+       union acpi_object *obj, *elements;
+
+       if (bridge->ignore_reset_delay)
+               pdev->d3cold_delay = 0;
+
+       obj = acpi_evaluate_dsm(handle, pci_acpi_dsm_uuid, 3,
+                               FUNCTION_DELAY_DSM, NULL);
+       if (!obj)
+               return;
+
+       if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 5) {
+               elements = obj->package.elements;
+               if (elements[0].type == ACPI_TYPE_INTEGER) {
+                       value = (int)elements[0].integer.value / 1000;
+                       if (value < PCI_PM_D3COLD_WAIT)
+                               pdev->d3cold_delay = value;
+               }
+               if (elements[3].type == ACPI_TYPE_INTEGER) {
+                       value = (int)elements[3].integer.value / 1000;
+                       if (value < PCI_PM_D3_WAIT)
+                               pdev->d3_delay = value;
+               }
+       }
+       ACPI_FREE(obj);
+}
+
 static void pci_acpi_setup(struct device *dev)
 {
        struct pci_dev *pci_dev = to_pci_dev(dev);
@@ -569,6 +650,8 @@ static void pci_acpi_setup(struct device *dev)
        if (!adev)
                return;
 
+       pci_acpi_optimize_delay(pci_dev, adev->handle);
+
        pci_acpi_add_pm_notifier(adev, pci_dev);
        if (!adev->wakeup.flags.valid)
                return;