[PATCH 05/15] PCI: Save PCI-X state in the saved capability store

[David Matlack <dmatlack@google.com>]

Save and restore the PCI-X Command register through the per-device saved
capability store instead of a private pci_cap_saved_state buffer.

Reserve the register by its configuration space offset during device setup
so that the save and restore paths no longer have to locate a buffer, and
so that the saved value can be found without knowing how the PCI core
happens to lay its buffers out.

While here, make pci_save_pcix_state() void now that it cannot fail.

No functional change intended.

Assisted-by: LLM
Signed-off-by: David Matlack <dmatlack@google.com>
---
 drivers/pci/pci.c | 43 ++++++++++++++-----------------------------
 1 file changed, 14 insertions(+), 29 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1c2c572aa49c..9e49806c6891 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1733,40 +1733,26 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
 	}
 }
 
-static int pci_save_pcix_state(struct pci_dev *dev)
+static void pci_save_pcix_state(struct pci_dev *dev)
 {
 	int pos;
-	struct pci_cap_saved_state *save_state;
 
 	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
 	if (!pos)
-		return 0;
-
-	save_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
-	if (!save_state) {
-		pci_err(dev, "buffer not found in %s\n", __func__);
-		return -ENOMEM;
-	}
-
-	pci_read_config_word(dev, pos + PCI_X_CMD,
-			     (u16 *)save_state->cap.data);
+		return;
 
-	return 0;
+	pci_save_cap_word(dev, pos + PCI_X_CMD);
 }
 
 static void pci_restore_pcix_state(struct pci_dev *dev)
 {
-	int i = 0, pos;
-	struct pci_cap_saved_state *save_state;
-	u16 *cap;
+	int pos;
 
-	save_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
 	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
-	if (!save_state || !pos)
+	if (!pos)
 		return;
-	cap = (u16 *)&save_state->cap.data[0];
 
-	pci_write_config_word(dev, pos + PCI_X_CMD, cap[i++]);
+	pci_restore_cap_word(dev, pos + PCI_X_CMD);
 }
 
 /**
@@ -1786,11 +1772,7 @@ int pci_save_state(struct pci_dev *dev)
 	dev->state_saved = true;
 
 	pci_save_pcie_state(dev);
-
-	i = pci_save_pcix_state(dev);
-	if (i != 0)
-		return i;
-
+	pci_save_pcix_state(dev);
 	pci_save_dpc_state(dev);
 	pci_save_aer_state(dev);
 	pci_save_ptm_state(dev);
@@ -3579,7 +3561,7 @@ int pci_add_ext_cap_save_buffer(struct pci_dev *dev, u16 cap, unsigned int size)
 void pci_allocate_cap_save_buffers(struct pci_dev *dev)
 {
 	unsigned int i;
-	int error;
+	int error, pos;
 
 	for (i = 0; pci_is_pcie(dev) && i < ARRAY_SIZE(pcie_saved_regs); i++) {
 		unsigned int off = dev->pcie_cap + pcie_saved_regs[i];
@@ -3591,9 +3573,12 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
 		}
 	}
 
-	error = pci_add_cap_save_buffer(dev, PCI_CAP_ID_PCIX, sizeof(u16));
-	if (error)
-		pci_err(dev, "unable to preallocate PCI-X save buffer\n");
+	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+	if (pos) {
+		error = pci_reserve_saved_cap(dev, pos + PCI_X_CMD, sizeof(u16));
+		if (error)
+			pci_err(dev, "unable to reserve PCI-X save state\n");
+	}
 
 	error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_LTR,
 					    2 * sizeof(u16));
-- 
2.56.0.rc1.315.gc6ed9934b7-goog