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Subject[PATCH] pci: support Thunderbolt requirements for I/O resources.
Date
Every Thunderbolt-based devices or Thunderbolt-connected
devices should not allocate PCI I/O resources
per Thunderbolt specs.

On a Thunderbolt PC, BIOS is responsible to allocate IO
resources. Kernel shouldn't allocate the PCI I/O resources
as it interferes with BIOS operation.
Doing this may cause the devices in the Thunderbolt chain
not being detected or added, or worse to stuck the
Thunderbolt Host controller.

To prevent this, we detect a chain contains a Thunderbolt
device by checking the Thunderbolt PCI device id.

The validation is carried out at the pci_enable_device_flags()
function that checks the PCI device or bridge is Thunderbolt
chained and avoid IO resources allocation.

In addition, decode_bar() and pci_bridge_check_ranges()
function has been internally checked for Thunderbolt
as well to ensure no IO resources are allocated.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
---
drivers/pci/pci.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 2 ++
drivers/pci/probe.c | 3 ++-
drivers/pci/setup-bus.c | 4 ++--
include/linux/pci.h | 2 ++
5 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 625a4ac..41c2619 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -198,6 +198,62 @@ static int __pci_bus_find_cap_start(struct pci_bus *bus,
}

/**
+ * pci_is_thunderbolt_device - checks PCI device is Thunderbolt-based.
+ * The only existing way is to check the device id is allocated to Thunderbolt.
+ * @dev: the PCI device structure to check against
+ *
+ * Returns true if the PCI device is of the Thunderbolt type.
+ */
+bool pci_is_thunderbolt_device(struct pci_dev *dev)
+{
+ if ((dev->vendor == PCI_VENDOR_ID_INTEL) &&
+ ((dev->device == 0xcaca)
+ || (dev->device == 0x1513)
+ || (dev->device == 0xcbca)
+ || (dev->device == 0x151A)
+ || (dev->device == 0x151B)
+ || (dev->device == 0x1549)
+ || (dev->device == 0x1547)
+ || (dev->device == 0x1548)
+ || (dev->device == 0x1566)
+ || (dev->device == 0x1567)
+ || (dev->device == 0x1569)
+ || (dev->device == 0x1568)
+ || (dev->device == 0x156A)
+ || (dev->device == 0x156B)
+ || (dev->device == 0x156C)
+ || (dev->device == 0x156D)
+ || (dev->device == 0x1579)
+ || (dev->device == 0x157A)
+ || (dev->device == 0x157D)
+ || (dev->device == 0x157E)))
+ return true;
+
+ return false;
+}
+EXPORT_SYMBOL(pci_is_thunderbolt_device);
+
+/**
+ * pci_is_connected_to_thunderbolt - check if connected to a Thunderbolt chain.
+ * @dev: the PCI device structure to check against
+ *
+ * Returns true if the PCI device s connected is connected to a
+ * Thunderbolt-based in the chain.
+ */
+bool pci_is_connected_to_thunderbolt(struct pci_dev *dev)
+{
+ struct pci_dev *bridge;
+
+ if (pci_is_thunderbolt_device(dev))
+ return true;
+ bridge = pci_upstream_bridge(dev);
+ if (bridge)
+ return pci_is_connected_to_thunderbolt(bridge);
+ return false;
+}
+EXPORT_SYMBOL(pci_is_connected_to_thunderbolt);
+
+/**
* pci_find_capability - query for devices' capabilities
* @dev: PCI device to query
* @cap: capability code
@@ -1285,6 +1341,14 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
if (atomic_inc_return(&dev->enable_cnt) > 1)
return 0; /* already enabled */

+ /*
+ * if IO resource have been requested, but the device is connected
+ * to Thunderbolt chain, don't allocate IO resource
+ */
+ if ((flags & IORESOURCE_IO)
+ && pci_is_connected_to_thunderbolt(dev))
+ flags &= ~IORESOURCE_IO;
+
bridge = pci_upstream_bridge(dev);
if (bridge)
pci_enable_bridge(bridge);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 0601890..fb9a3b1 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -4,6 +4,8 @@
#define PCI_CFG_SPACE_SIZE 256
#define PCI_CFG_SPACE_EXP_SIZE 4096

+bool pci_is_thunderbolt_device(struct pci_dev *dev);
+
extern const unsigned char pcie_link_speed[];

/* Functions internal to the PCI core code */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 5ed9930..d8171af 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -131,7 +131,8 @@ static inline unsigned long decode_bar(struct pci_dev *dev, u32 bar)

if ((bar & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
flags = bar & ~PCI_BASE_ADDRESS_IO_MASK;
- flags |= IORESOURCE_IO;
+ if (!pci_is_connected_to_thunderbolt(dev))
+ flags |= IORESOURCE_IO;
return flags;
}

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 0482235..79ac38f 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -663,12 +663,12 @@ static void pci_bridge_check_ranges(struct pci_bus *bus)
b_res[1].flags |= IORESOURCE_MEM;

pci_read_config_word(bridge, PCI_IO_BASE, &io);
- if (!io) {
+ if (!io || pci_is_thunderbolt_device(bridge)) {
pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0);
pci_read_config_word(bridge, PCI_IO_BASE, &io);
pci_write_config_word(bridge, PCI_IO_BASE, 0x0);
}
- if (io)
+ if (io && !pci_is_thunderbolt_device(bridge))
b_res[0].flags |= IORESOURCE_IO;

/* DECchip 21050 pass 2 errata: the bridge may miss an address
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2a8c405..09ddc2c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -931,6 +931,8 @@ int __must_check pci_enable_device_io(struct pci_dev *dev);
int __must_check pci_enable_device_mem(struct pci_dev *dev);
int __must_check pci_reenable_device(struct pci_dev *);
int __must_check pcim_enable_device(struct pci_dev *pdev);
+
+bool pci_is_connected_to_thunderbolt(struct pci_dev *dev);
void pcim_pin_device(struct pci_dev *pdev);

static inline int pci_is_enabled(struct pci_dev *pdev)
--
1.9.1
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