Convert an ACPI CA handle to a struct pci_dev.
Performing this lookup dynamically allows us to get rid of the
ACPI-PCI binding code, which:
- eliminates struct acpi_device vs struct pci_dev lifetime issues
- lays more groundwork for eliminating .start from acpi_device_ops
and thus simplifying ACPI drivers
- whacks out a lot of code
This change also changes the time-space tradeoff ever so slightly.
Looking up the ACPI-PCI binding is never in the performance path, and by
eliminating this caching, we save 24 bytes for each _ADR device in the
ACPI namespace.
Signed-off-by: Alex Chiang <achiang@xxxxxx>
---
drivers/acpi/pci_bind.c | 83 +++++++++++++++++++++++++++++++++++++++++++
include/acpi/acpi_drivers.h | 1 +
2 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/drivers/acpi/pci_bind.c b/drivers/acpi/pci_bind.c
index 236765c..584fa30 100644
--- a/drivers/acpi/pci_bind.c
+++ b/drivers/acpi/pci_bind.c
@@ -56,6 +56,89 @@ static void acpi_pci_data_handler(acpi_handle handle, u32 function,
return;
}
+struct acpi_handle_node {
+ struct list_head node;
+ acpi_handle handle;
+};
+
+/**
+ * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
+ * @handle: the handle in question
+ *
+ * Given an ACPI CA handle, the desired PCI device is located in the
+ * list of PCI devices.
+ *
+ * If the device is found, its reference count is increased and this
+ * function returns a pointer to its data structure. The caller must
+ * decrement the reference count by calling pci_dev_put().
+ * If no device is found, %NULL is returned.
+ */
+struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
+{
+ int dev, fn;
+ unsigned long long adr;
+ acpi_status status;
+ acpi_handle phandle;
+ struct pci_bus *pbus;
+ struct pci_dev *pdev = NULL;
+ struct acpi_handle_node *node, *tmp;
+ struct acpi_pci_root *root;
+ LIST_HEAD(device_list);
+
+ /*
+ * Walk up the ACPI CA namespace until we reach a PCI root bridge.
+ */
+ phandle = handle;
+ while (!acpi_is_root_bridge(phandle)) {
+ node = kzalloc(sizeof(struct acpi_handle_node), GFP_KERNEL);
+ if (!node)
+ goto out;
+
+ INIT_LIST_HEAD(&node->node);
+ node->handle = phandle;
+ list_add(&node->node, &device_list);
+
+ status = acpi_get_parent(phandle, &phandle);
+ if (ACPI_FAILURE(status))
+ goto out;
+ }
+
+ root = acpi_pci_find_root(phandle);
+ if (!root)
+ goto out;
+
+ pbus = pci_find_bus(root->id.segment, root->id.bus);
+ if (!pbus)
+ goto out;
+
+ /*
+ * Now, walk back down the PCI device tree until we return to our
+ * original handle. Assumes that everything between the PCI root
+ * bridge and the device we're looking for must be a P2P bridge.
+ */
+ list_for_each_entry_safe(node, tmp, &device_list, node) {
+ acpi_handle hnd = node->handle;
+ status = acpi_evaluate_integer(hnd, "_ADR", NULL, &adr);
+ if (ACPI_FAILURE(status))
+ goto out;
+ dev = (adr >> 16) & 0xffff;
+ fn = adr & 0xffff;
+
+ list_del(&node->node);
+ kfree(node);
+
+ pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
+ if (hnd == handle)
+ break;
+
+ pbus = pdev->subordinate;
+ pci_dev_put(pdev);
+ }
+out:
+ return pdev;
+}
+EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
+
/**
* acpi_get_pci_id
* ------------------
diff --git a/include/acpi/acpi_drivers.h b/include/acpi/acpi_drivers.h
index bbe9207..1ef529b 100644
--- a/include/acpi/acpi_drivers.h
+++ b/include/acpi/acpi_drivers.h
@@ -97,6 +97,7 @@ void acpi_pci_irq_del_prt(int segment, int bus);
struct pci_bus;
+struct pci_dev *acpi_get_pci_dev(acpi_handle);
acpi_status acpi_get_pci_id(acpi_handle handle, struct acpi_pci_id *id);
int acpi_pci_bind_root(struct acpi_device *device, struct acpi_pci_id *id,
struct pci_bus *bus);
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