Pci_dummy_ops does nothing when we use it to read/write
pci_device. So we can isolate pci device by replace its
bus pci_ops by pci_dummy_ops. This is preparation for
the later patch.
Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
---
drivers/pci/pci.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 4 +++
2 files changed, 66 insertions(+), 0 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index af34057..283e82e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2226,6 +2226,68 @@ bool pci_serial_number_changed(struct pci_dev *pdev)
}
EXPORT_SYMBOL(pci_serial_number_changed);
+static int pci_dummy_read(struct pci_bus *bus, unsigned int devfn,
+ int where, int size, u32 *val)
+{
+ return PCIBIOS_DEVICE_NOT_FOUND;
+}
+
+static int pci_dummy_write(struct pci_bus *bus, unsigned int devfn,
+ int reg, int size, u32 val)
+{
+ return PCIBIOS_DEVICE_NOT_FOUND;
+}
+
+static struct pci_ops pci_dummy_ops = {
+ .read = pci_dummy_read,
+ .write = pci_dummy_write,
+};
+
+static DEFINE_SPINLOCK(pci_freeze_lock);
+/**
+ * pci_bus_freeze_device - freeze pci bus to access pci device
+ * @bus: the pci bus to freeze
+ *
+ * Replace pci bus ops by pci_dummy_ops, protect system from
+ * accessing pci devices.
+ */
+void pci_bus_freeze_device(struct pci_bus *bus)
+{
+ struct pci_ops *ops;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pci_freeze_lock, flags);
+ if (bus->is_frozen)
+ goto out;
+ bus->is_frozen = 1;
+ ops = pci_bus_set_ops(bus, &pci_dummy_ops);
+ bus->save_ops = ops;
+out:
+ spin_unlock_irqrestore(&pci_freeze_lock, flags);
+}
+
+/**
+ * pci_bus_unfreeze_device - unfreeze pci bus to acess pci devices
+ * @bus: the pci bus to unfreeze
+ *
+ * Restore pci bus original ops, so pci bus can access
+ * pci devices normally.
+ */
+void pci_bus_unfreeze_device(struct pci_bus *bus)
+{
+ unsigned long flags;
+
+ BUG_ON(!bus->save_ops);
+ spin_lock_irqsave(&pci_freeze_lock, flags);
+ if (!bus->is_frozen)
+ goto out;
+ pci_bus_set_ops(bus, bus->save_ops);
+ bus->save_ops = NULL;
+ bus->is_frozen = 0;
+out:
+ spin_unlock_irqrestore(&pci_freeze_lock, flags);
+}
+
/**
* pci_configure_ari - enable or disable ARI forwarding
* @dev: the PCI device
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d60c0b6..e3dd4ea 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -442,6 +442,7 @@ struct pci_bus {
struct resource busn_res; /* bus numbers routed to this bus */
struct pci_ops *ops; /* configuration access functions */
+ struct pci_ops *save_ops; /* save configuration access functions */
struct msi_chip *msi; /* MSI controller */
void *sysdata; /* hook for sys-specific extension */
struct proc_dir_entry *procdir; /* directory entry in /proc/bus/pci */
@@ -460,6 +461,7 @@ struct pci_bus {
struct bin_attribute *legacy_io; /* legacy I/O for this bus */
struct bin_attribute *legacy_mem; /* legacy mem */
unsigned int is_added:1;
+ unsigned int is_frozen:1;
};
#define pci_bus_b(n) list_entry(n, struct pci_bus, node)
@@ -1026,6 +1028,8 @@ ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
bool pci_serial_number_changed(struct pci_dev *pdev);
+void pci_bus_freeze_device(struct pci_bus *bus);
+void pci_bus_unfreeze_device(struct pci_bus *bus);
/* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx);
--
1.7.1
--
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