[PATCH v6 2/9] PCI: Export pci_dev_save_and_disable() and pci_dev_restore()

[Srirangan Madhavan <smadhavan@nvidia.com>]

Export pci_dev_save_and_disable() and pci_dev_restore() so CXL reset
orchestration can reuse the PCI core reset lifecycle for non-standard
reset flows.

These helpers invoke driver reset_prepare/reset_done callbacks, save and
restore PCI config state, and disable the device while the caller holds
the device lock.

Signed-off-by: Srirangan Madhavan <smadhavan@nvidia.com>
---
 drivers/pci/pci.c   | 22 ++++++++++++++++++++--
 include/linux/pci.h |  2 ++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d34266651ad0..75d2f4074750 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5003,7 +5003,15 @@ void pci_dev_unlock(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_dev_unlock);
 
-static void pci_dev_save_and_disable(struct pci_dev *dev)
+/**
+ * pci_dev_save_and_disable - Save device state and disable it
+ * @dev: PCI device to save and disable
+ *
+ * Save the PCI configuration state, invoke the driver's reset_prepare()
+ * callback if present, and disable the device by clearing the Command
+ * register. The device lock must be held by the caller.
+ */
+void pci_dev_save_and_disable(struct pci_dev *dev)
 {
 	const struct pci_error_handlers *err_handler =
 			dev->driver ? dev->driver->err_handler : NULL;
@@ -5036,8 +5044,17 @@ static void pci_dev_save_and_disable(struct pci_dev *dev)
 	 */
 	pci_write_config_word(dev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
 }
+EXPORT_SYMBOL_GPL(pci_dev_save_and_disable);
 
-static void pci_dev_restore(struct pci_dev *dev)
+/**
+ * pci_dev_restore - Restore device state after reset
+ * @dev: PCI device to restore
+ *
+ * Restore the saved PCI configuration state and invoke the driver's
+ * reset_done() callback if present. The device lock must be held by the
+ * caller.
+ */
+void pci_dev_restore(struct pci_dev *dev)
 {
 	const struct pci_error_handlers *err_handler =
 			dev->driver ? dev->driver->err_handler : NULL;
@@ -5054,6 +5071,7 @@ static void pci_dev_restore(struct pci_dev *dev)
 	else if (dev->driver)
 		pci_warn(dev, "reset done");
 }
+EXPORT_SYMBOL_GPL(pci_dev_restore);
 
 /* dev->reset_methods[] is a 0-terminated list of indices into this array */
 const struct pci_reset_fn_method pci_reset_fn_methods[] = {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2c4454583c11..d6303e16e11b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2012,6 +2012,8 @@ void pci_dev_lock(struct pci_dev *dev);
 int pci_dev_trylock(struct pci_dev *dev);
 void pci_dev_unlock(struct pci_dev *dev);
 DEFINE_GUARD(pci_dev, struct pci_dev *, pci_dev_lock(_T), pci_dev_unlock(_T))
+void pci_dev_save_and_disable(struct pci_dev *dev);
+void pci_dev_restore(struct pci_dev *dev);
 
 /*
  * PCI domain support.  Sometimes called PCI segment (eg by ACPI),
-- 
2.43.0