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pci_root: track downstream bus range

PATCH In review Bjorn Helgaas 2 participants 4 messages Mar 11, 2010 – Apr 4, 2010

Subsystems (4)
x86 ACPI PCI ACPI component architecture (acpica)
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Bjorn Helgaas

author
#0 lore raw

v4 cover pci_root: track downstream bus range

These patches keep track of both the beginning and end of the bus number range under a PCI host bridge (previously we only kept the beginning) and make that range available to the arch code, which will need it so support the _CBA mechanism for reporting MMCONFIG regions.

Changes from v3 to v4:
- Cleanup secondary.start init (Kenji).

Changes from v2 to v3:
- Rework to use struct resource with IORESOURCE_BUS.
---

Bjorn Helgaas (2):
ACPI: pci_root: save downstream bus range
ACPI: pci_root: pass acpi_pci_root to arch-specific scan

 arch/ia64/pci/pci.c         |    5 +++
 arch/x86/pci/acpi.c         |    5 +++
 drivers/acpi/pci_root.c     |   67 ++++++++++++++++++++++++++-----------------
 include/acpi/acpi_bus.h     |    2 +
 include/acpi/acpi_drivers.h |    3 +-
 5 files changed, 50 insertions(+), 32 deletions(-)
author
#1 lore raw

PATCH v4 1/2 ACPI: pci_root: save downstream bus range

Previously, we only saved the root bus number, i.e., the beginning of the downstream bus range. We now support IORESOURCE_BUS resources, so this patch uses that to keep track of both the beginning and the end of the downstream bus range.

It's important to know both the beginning and the end for supporting _CBA (see PCI Firmware spec, rev 3.0, sec 4.1.3) and so we know the limits for any possible PCI bus renumbering (we can't renumber downstream buses to be outside the bus number range claimed by the host bridge).

It's clear from the spec that the bus range is supposed to be in _CRS, but if we don't find it there, we'll assume [_BBN - 0xFF] or [0 - 0xFF].

Signed-off-by Bjorn Helgaas <[email protected]>
Reviewed-by Kenji Kaneshige <[email protected]>

---

 drivers/acpi/pci_root.c |   67 ++++++++++++++++++++++++++++-------------------
 include/acpi/acpi_bus.h |    2 +
 2 files changed, 41 insertions(+), 28 deletions(-)
drivers/acpi/pci_root.c +40 -27
index d724736..bf476fe 100644
@@ -119,7 +119,8 @@ acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
 	struct acpi_pci_root *root;
 	
 	list_for_each_entry(root, &acpi_pci_roots, node)
-		if ((root->segment == (u16) seg) && (root->bus_nr == (u16) bus))
+		if ((root->segment == (u16) seg) &&
+		    (root->secondary.start == (u16) bus))
 			return root->device->handle;
 	return NULL;		
 }

@@ -153,7 +154,7 @@ EXPORT_SYMBOL_GPL(acpi_is_root_bridge);
 static acpi_status
 get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
 {
-	int *busnr = data;
+	struct resource *res = data;
 	struct acpi_resource_address64 address;
 
 	if (resource->type != ACPI_RESOURCE_TYPE_ADDRESS16 &&

@@ -163,28 +164,27 @@ get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
 
 	acpi_resource_to_address64(resource, &address);
 	if ((address.address_length > 0) &&
-	    (address.resource_type == ACPI_BUS_NUMBER_RANGE))
-		*busnr = address.minimum;
+	    (address.resource_type == ACPI_BUS_NUMBER_RANGE)) {
+		res->start = address.minimum;
+		res->end = address.minimum + address.address_length - 1;
+	}
 
 	return AE_OK;
 }
 
 static acpi_status try_get_root_bridge_busnr(acpi_handle handle,
-					     unsigned long long *bus)
+					     struct resource *res)
 {
 	acpi_status status;
-	int busnum;
 
-	busnum = -1;
+	res->start = -1;
 	status =
 	    acpi_walk_resources(handle, METHOD_NAME__CRS,
-				get_root_bridge_busnr_callback, &busnum);
+				get_root_bridge_busnr_callback, res);
 	if (ACPI_FAILURE(status))
 		return status;
-	/* Check if we really get a bus number from _CRS */
-	if (busnum == -1)
+	if (res->start == -1)
 		return AE_ERROR;
-	*bus = busnum;
 	return AE_OK;
 }
 

@@ -428,34 +428,47 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	struct acpi_device *child;
 	u32 flags, base_flags;
 
+	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
+	if (!root)
+		return -ENOMEM;
+
 	segment = 0;
 	status = acpi_evaluate_integer(device->handle, METHOD_NAME__SEG, NULL,
 				       &segment);
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 		printk(KERN_ERR PREFIX "can't evaluate _SEG\n");
-		return -ENODEV;
+		result = -ENODEV;
+		goto end;
 	}
 
 	/* Check _CRS first, then _BBN.  If no _BBN, default to zero. */
-	bus = 0;
-	status = try_get_root_bridge_busnr(device->handle, &bus);
+	root->secondary.flags = IORESOURCE_BUS;
+	status = try_get_root_bridge_busnr(device->handle, &root->secondary);
 	if (ACPI_FAILURE(status)) {
+		/*
+		 * We need both the start and end of the downstream bus range
+		 * to interpret _CBA (MMCONFIG base address), so it really is
+		 * supposed to be in _CRS.  If we don't find it there, all we
+		 * can do is assume [_BBN-0xFF] or [0-0xFF].
+		 */
+		root->secondary.end = 0xFF;
+		printk(KERN_WARNING FW_BUG PREFIX
+		       "no secondary bus range in _CRS\n");
 		status = acpi_evaluate_integer(device->handle, METHOD_NAME__BBN,					       NULL, &bus);
-		if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
-			printk(KERN_ERR PREFIX
-			     "no bus number in _CRS and can't evaluate _BBN\n");
-			return -ENODEV;
+		if (ACPI_SUCCESS(status))
+			root->secondary.start = bus;
+		else if (status == AE_NOT_FOUND)
+			root->secondary.start = 0;
+		else {
+			printk(KERN_ERR PREFIX "can't evaluate _BBN\n");
+			result = -ENODEV;
+			goto end;
 		}
 	}
 
-	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
-	if (!root)
-		return -ENOMEM;
-
 	INIT_LIST_HEAD(&root->node);
 	root->device = device;
 	root->segment = segment & 0xFFFF;
-	root->bus_nr = bus & 0xFF;
 	strcpy(acpi_device_name(device), ACPI_PCI_ROOT_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
 	device->driver_data = root;

@@ -474,9 +487,9 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	/* TBD: Locking */
 	list_add_tail(&root->node, &acpi_pci_roots);
 
-	printk(KERN_INFO PREFIX "%s [%s] (%04x:%02x)\n",
+	printk(KERN_INFO PREFIX "%s [%s] (domain %04x %pR)\n",
 	       acpi_device_name(device), acpi_device_bid(device),
-	       root->segment, root->bus_nr);
+	       root->segment, &root->secondary);
 
 	/*
 	 * Scan the Root Bridge

@@ -485,11 +498,11 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	 * PCI namespace does not get created until this call is made (and 
 	 * thus the root bridge's pci_dev does not exist).
 	 */
-	root->bus = pci_acpi_scan_root(device, segment, bus);
+	root->bus = pci_acpi_scan_root(device, segment, root->secondary.start);
 	if (!root->bus) {
 		printk(KERN_ERR PREFIX
 			    "Bus %04x:%02x not present in PCI namespace\n",
-			    root->segment, root->bus_nr);
+			    root->segment, (unsigned int)root->secondary.start);
 		result = -ENODEV;
 		goto end;
 	}
include/acpi/acpi_bus.h +1 -1
index 7bf83dd..baacd98 100644
@@ -373,7 +373,7 @@ struct acpi_pci_root {
 	struct acpi_pci_id id;
 	struct pci_bus *bus;
 	u16 segment;
-	u8 bus_nr;
+	struct resource secondary;	/* downstream bus range */
 
 	u32 osc_support_set;	/* _OSC state of support bits */
 	u32 osc_control_set;	/* _OSC state of control bits */
author
#2 lore raw

PATCH v4 2/2 ACPI: pci_root: pass acpi_pci_root to arch-specific scan

In reply to Bjorn Helgaas

The acpi_pci_root structure contains all the individual items (acpi_device, domain, bus number) we pass to pci_acpi_scan_root(), so just pass the single acpi_pci_root pointer directly.

This will make it easier to add _CBA support later. For _CBA, we need the entire downstream bus range, not just the base bus number. We have that in the acpi_pci_root structure, so passing the pointer makes it available to the arch-specific code.

Signed-off-by Bjorn Helgaas <[email protected]>
Reviewed-by Kenji Kaneshige <[email protected]>

---

 arch/ia64/pci/pci.c         |    5 ++++-
 arch/x86/pci/acpi.c         |    5 ++++-
 drivers/acpi/pci_root.c     |    2 +-
 include/acpi/acpi_drivers.h |    3 +--
 4 files changed, 10 insertions(+), 5 deletions(-)
arch/ia64/pci/pci.c +4 -1
index 64aff52..aa2533a 100644
@@ -335,8 +335,11 @@ pcibios_setup_root_windows(struct pci_bus *bus, struct pci_controller *ctrl)
 }
 
 struct pci_bus * __devinit
-pci_acpi_scan_root(struct acpi_device *device, int domain, int bus)
+pci_acpi_scan_root(struct acpi_pci_root *root)
 {
+	struct acpi_device *device = root->device;
+	int domain = root->segment;
+	int bus = root->secondary.start;
 	struct pci_controller *controller;
 	unsigned int windows = 0;
 	struct pci_bus *pbus;
arch/x86/pci/acpi.c +4 -1
index 5f11ff6..0c36ad5 100644
@@ -215,8 +215,11 @@ res_alloc_fail:
 	return;
 }
 
-struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int domain, int busnum)
+struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 {
+	struct acpi_device *device = root->device;
+	int domain = root->segment;
+	int busnum = root->secondary.start;
 	struct pci_bus *bus;
 	struct pci_sysdata *sd;
 	int node;
drivers/acpi/pci_root.c +1 -1
index bf476fe..680450c 100644
@@ -498,7 +498,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	 * PCI namespace does not get created until this call is made (and 
 	 * thus the root bridge's pci_dev does not exist).
 	 */
-	root->bus = pci_acpi_scan_root(device, segment, root->secondary.start);
+	root->bus = pci_acpi_scan_root(root);
 	if (!root->bus) {
 		printk(KERN_ERR PREFIX
 			    "Bus %04x:%02x not present in PCI namespace\n",
include/acpi/acpi_drivers.h +1 -2
index 3a4767c..16903b3 100644
@@ -102,8 +102,7 @@ int acpi_pci_bind_root(struct acpi_device *device);
 
 /* Arch-defined function to add a bus to the system */
 
-struct pci_bus *pci_acpi_scan_root(struct acpi_device *device, int domain,
-				   int bus);
+struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root);
 void pci_acpi_crs_quirks(void);
 
 /* --------------------------------------------------------------------------