[PATCH v2 10/17] PCI/TPH: Save TPH state in the saved capability store

[David Matlack <dmatlack@google.com>]

Save and restore the TPH Control register and Steering Tag table through
the per-device saved capability store instead of a private
pci_cap_saved_state buffer.

The Steering Tag table is variable length, so pci_tph_init() had to compute
a buffer size and both the save and restore loops had to walk that buffer
in step with configuration space. Reserve the table by offset instead so
that the loops can address the entries directly.

Reserve the registers in pci_reserve_tph_state(), called from
pci_tph_init(), and report a refused reservation. pci_tph_init() ignored
the return value of pci_add_ext_cap_save_buffer(), so a failed
allocation left TPH state unsaved without any message. An allocation
failure is now reported once by pci_saved_caps_finalize().

No other functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
---
 drivers/pci/tph.c | 54 +++++++++++++++++++++--------------------------
 1 file changed, 24 insertions(+), 30 deletions(-)

diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
index 655ffd60e62f..3ab8d5b2ab10 100644
--- a/drivers/pci/tph.c
+++ b/drivers/pci/tph.c
@@ -439,10 +439,7 @@ EXPORT_SYMBOL(pcie_enable_tph);
 
 void pci_restore_tph_state(struct pci_dev *pdev)
 {
-	struct pci_cap_saved_state *save_state;
 	int num_entries, i, offset;
-	u16 *st_entry;
-	u32 *cap;
 
 	if (!pdev->tph_cap)
 		return;
@@ -450,29 +447,19 @@ void pci_restore_tph_state(struct pci_dev *pdev)
 	if (!pdev->tph_enabled)
 		return;
 
-	save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_TPH);
-	if (!save_state)
-		return;
-
 	/* Restore control register and all ST entries */
-	cap = &save_state->cap.data[0];
-	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, *cap++);
-	st_entry = (u16 *)cap;
+	pci_restore_cap_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL);
 	offset = PCI_TPH_BASE_SIZEOF;
 	num_entries = pcie_tph_get_st_table_size(pdev);
 	for (i = 0; i < num_entries; i++) {
-		pci_write_config_word(pdev, pdev->tph_cap + offset,
-				      *st_entry++);
+		pci_restore_cap_word(pdev, pdev->tph_cap + offset);
 		offset += sizeof(u16);
 	}
 }
 
 void pci_save_tph_state(struct pci_dev *pdev)
 {
-	struct pci_cap_saved_state *save_state;
 	int num_entries, i, offset;
-	u16 *st_entry;
-	u32 *cap;
 
 	if (!pdev->tph_cap)
 		return;
@@ -480,21 +467,14 @@ void pci_save_tph_state(struct pci_dev *pdev)
 	if (!pdev->tph_enabled)
 		return;
 
-	save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_TPH);
-	if (!save_state)
-		return;
-
 	/* Save control register */
-	cap = &save_state->cap.data[0];
-	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, cap++);
+	pci_save_cap_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL);
 
 	/* Save all ST entries in extended capability structure */
-	st_entry = (u16 *)cap;
 	offset = PCI_TPH_BASE_SIZEOF;
 	num_entries = pcie_tph_get_st_table_size(pdev);
 	for (i = 0; i < num_entries; i++) {
-		pci_read_config_word(pdev, pdev->tph_cap + offset,
-				     st_entry++);
+		pci_save_cap_word(pdev, pdev->tph_cap + offset);
 		offset += sizeof(u16);
 	}
 }
@@ -506,16 +486,30 @@ void pci_no_tph(void)
 	pr_info("PCIe TPH is disabled\n");
 }
 
-void pci_tph_init(struct pci_dev *pdev)
+static void pci_reserve_tph_state(struct pci_dev *pdev)
 {
-	int num_entries;
-	u32 save_size;
+	unsigned int off, len;
+	int num_entries, rc;
+
+	off = pdev->tph_cap + PCI_TPH_CTRL;
+	rc = pci_reserve_saved_cap(pdev, off, sizeof(u32));
 
+	num_entries = pcie_tph_get_st_table_size(pdev);
+	if (!rc && num_entries) {
+		off = pdev->tph_cap + PCI_TPH_BASE_SIZEOF;
+		len = num_entries * sizeof(u16);
+		rc = pci_reserve_saved_cap(pdev, off, len);
+	}
+	if (rc)
+		pci_err(pdev, "unable to reserve TPH save state (%pe)\n",
+			ERR_PTR(rc));
+}
+
+void pci_tph_init(struct pci_dev *pdev)
+{
 	pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
 	if (!pdev->tph_cap)
 		return;
 
-	num_entries = pcie_tph_get_st_table_size(pdev);
-	save_size = sizeof(u32) + num_entries * sizeof(u16);
-	pci_add_ext_cap_save_buffer(pdev, PCI_EXT_CAP_ID_TPH, save_size);
+	pci_reserve_tph_state(pdev);
 }
-- 
2.56.0.455.g6c5a503b38-goog