shpchp: check firmware before taking control

Fix the following problems of shpchp driver about getting hotplug
control from firmware.

  - The shpchp driver must not control the hotplug controller if it
    fails to get control from the firmware. But current shpchp
    controls the hotplug controller regardless the result, because it
    doesn't check the return value of get_hp_hw_control_from_firmware().

  - Current shpchp driver doesn't support _OSC.

The pciehp driver already have the code for evaluating _OSC and OSHP
and shpchp and pciehp can share it. So this patch move that code from
pciehp to acpi_pcihp.c.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 81 insertions, 4 deletions

diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
index f8c187a763bd..93e37f0666ab 100644
--- a/drivers/pci/hotplug/acpi_pcihp.c
+++ b/drivers/pci/hotplug/acpi_pcihp.c
@@ -30,6 +30,7 @@
 #include <linux/types.h>
 #include <linux/pci.h>
 #include <linux/pci_hotplug.h>
+#include <linux/pci-acpi.h>
 #include <acpi/acpi.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/actypes.h>
@@ -299,7 +300,7 @@ free_and_return:
  *
  * @handle - the handle of the hotplug controller.
  */
-acpi_status acpi_run_oshp(acpi_handle handle)
+static acpi_status acpi_run_oshp(acpi_handle handle)
 {
 	acpi_status		status;
 	struct acpi_buffer	string = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -322,9 +323,6 @@ acpi_status acpi_run_oshp(acpi_handle handle)
 	kfree(string.pointer);
 	return status;
 }
-EXPORT_SYMBOL_GPL(acpi_run_oshp);
-
-
 
 /* acpi_get_hp_params_from_firmware
  *
@@ -374,6 +372,85 @@ acpi_status acpi_get_hp_params_from_firmware(struct pci_bus *bus,
 }
 EXPORT_SYMBOL_GPL(acpi_get_hp_params_from_firmware);
 
+/**
+ * acpi_get_hp_hw_control_from_firmware
+ * @dev: the pci_dev of the bridge that has a hotplug controller
+ * @flags: requested control bits for _OSC
+ *
+ * Attempt to take hotplug control from firmware.
+ */
+int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags)
+{
+	acpi_status status;
+	acpi_handle chandle, handle = DEVICE_ACPI_HANDLE(&(dev->dev));
+	struct pci_dev *pdev = dev;
+	struct pci_bus *parent;
+	struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
+
+	flags &= (OSC_PCI_EXPRESS_NATIVE_HP_CONTROL |
+		  OSC_SHPC_NATIVE_HP_CONTROL |
+		  OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
+	if (!flags) {
+		err("Invalid flags %u specified!\n", flags);
+		return -EINVAL;
+	}
+
+	/*
+	 * Per PCI firmware specification, we should run the ACPI _OSC
+	 * method to get control of hotplug hardware before using it. If
+	 * an _OSC is missing, we look for an OSHP to do the same thing.
+	 * To handle different BIOS behavior, we look for _OSC and OSHP
+	 * within the scope of the hotplug controller and its parents,
+	 * upto the host bridge under which this controller exists.
+	 */
+	while (!handle) {
+		/*
+		 * This hotplug controller was not listed in the ACPI name
+		 * space at all. Try to get acpi handle of parent pci bus.
+		 */
+		if (!pdev || !pdev->bus->parent)
+			break;
+		parent = pdev->bus->parent;
+		dbg("Could not find %s in acpi namespace, trying parent\n",
+		    pci_name(pdev));
+		if (!parent->self)
+			/* Parent must be a host bridge */
+			handle = acpi_get_pci_rootbridge_handle(
+					pci_domain_nr(parent),
+					parent->number);
+		else
+			handle = DEVICE_ACPI_HANDLE(&(parent->self->dev));
+		pdev = parent->self;
+	}
+
+	while (handle) {
+		acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
+		dbg("Trying to get hotplug control for %s \n",
+		    (char *)string.pointer);
+		status = pci_osc_control_set(handle, flags);
+		if (status == AE_NOT_FOUND)
+			status = acpi_run_oshp(handle);
+		if (ACPI_SUCCESS(status)) {
+			dbg("Gained control for hotplug HW for pci %s (%s)\n",
+			    pci_name(dev), (char *)string.pointer);
+			kfree(string.pointer);
+			return 0;
+		}
+		if (acpi_root_bridge(handle))
+			break;
+		chandle = handle;
+		status = acpi_get_parent(chandle, &handle);
+		if (ACPI_FAILURE(status))
+			break;
+	}
+
+	dbg("Cannot get control of hotplug hardware for pci %s\n",
+	    pci_name(dev));
+
+	kfree(string.pointer);
+	return -ENODEV;
+}
+EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
 
 /* acpi_root_bridge - check to see if this acpi object is a root bridge
  *