[PATCH v5 2/7] PCI: Export pci_dev_save_and_disable() and pci_dev_restore()

[<smadhavan@nvidia.com>]

From: Srirangan Madhavan <smadhavan@nvidia.com>

Export pci_dev_save_and_disable() and pci_dev_restore() so that
subsystems performing non-standard reset sequences (e.g. CXL)
can reuse the PCI core standard pre/post reset lifecycle:
driver reset_prepare/reset_done callbacks, PCI config space
save/restore, and device disable/re-enable.

Signed-off-by: Srirangan Madhavan <smadhavan@nvidia.com>
---
 drivers/pci/pci.c   | 21 +++++++++++++++++++--
 include/linux/pci.h |  3 +++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 497720c64d6d..2ef8d7274b30 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5033,7 +5033,15 @@ 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 any), 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;
@@ -5066,8 +5074,16 @@ 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 any). 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;
@@ -5084,6 +5100,7 @@ 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 1c270f1d5123..b229c1d93735 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2007,6 +2007,9 @@ 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),
  * a PCI domain is defined to be a set of PCI buses which share
--
2.43.0