linux-kernel - [PATCH V4 09/12] PCI/TPH: Add save/restore support for TPH

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Message-ID: <20240822204120.3634-10-wei.huang2@amd.com>
Date: Thu, 22 Aug 2024 15:41:17 -0500
From: Wei Huang <wei.huang2@....com>
To: <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <netdev@...r.kernel.org>
CC: <Jonathan.Cameron@...wei.com>, <helgaas@...nel.org>, <corbet@....net>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <alex.williamson@...hat.com>, <gospo@...adcom.com>,
	<michael.chan@...adcom.com>, <ajit.khaparde@...adcom.com>,
	<somnath.kotur@...adcom.com>, <andrew.gospodarek@...adcom.com>,
	<manoj.panicker2@....com>, <Eric.VanTassell@....com>, <wei.huang2@....com>,
	<vadim.fedorenko@...ux.dev>, <horms@...nel.org>, <bagasdotme@...il.com>,
	<bhelgaas@...gle.com>, <lukas@...ner.de>, <paul.e.luse@...el.com>,
	<jing2.liu@...el.com>
Subject: [PATCH V4 09/12] PCI/TPH: Add save/restore support for TPH

From: Paul Luse <paul.e.luse@...ux.intel.com>

Save and restore the configuration space for TPH capability to preserve
the settings during PCI reset. The settings include the TPH control
register and the ST table if present.

Co-developed-by: Wei Huang <wei.huang2@....com>
Signed-off-by: Wei Huang <wei.huang2@....com>
Co-developed-by: Jing Liu <jing2.liu@...el.com>
Signed-off-by: Jing Liu <jing2.liu@...el.com>
Reviewed-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Paul Luse <paul.e.luse@...ux.intel.com>
---
 drivers/pci/pci.c      |  2 ++
 drivers/pci/pci.h      |  4 +++
 drivers/pci/pcie/tph.c | 62 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e3a49f66982d..1e4960994b1a 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1813,6 +1813,7 @@ int pci_save_state(struct pci_dev *dev)
 	pci_save_dpc_state(dev);
 	pci_save_aer_state(dev);
 	pci_save_ptm_state(dev);
+	pci_save_tph_state(dev);
 	return pci_save_vc_state(dev);
 }
 EXPORT_SYMBOL(pci_save_state);
@@ -1917,6 +1918,7 @@ void pci_restore_state(struct pci_dev *dev)
 	pci_restore_vc_state(dev);
 	pci_restore_rebar_state(dev);
 	pci_restore_dpc_state(dev);
+	pci_restore_tph_state(dev);
 	pci_restore_ptm_state(dev);
 
 	pci_aer_clear_status(dev);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 289eddfe350b..d7c7f86e8705 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -572,8 +572,12 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)
 #endif /* CONFIG_PCI_IOV */
 
 #ifdef CONFIG_PCIE_TPH
+void pci_restore_tph_state(struct pci_dev *dev);
+void pci_save_tph_state(struct pci_dev *dev);
 void pci_tph_init(struct pci_dev *dev);
 #else
+static inline void pci_restore_tph_state(struct pci_dev *dev) { }
+static inline void pci_save_tph_state(struct pci_dev *dev) { }
 static inline void pci_tph_init(struct pci_dev *dev) { }
 #endif
 
diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
index 5bd194fb425e..b228ef5b7948 100644
--- a/drivers/pci/pcie/tph.c
+++ b/drivers/pci/pcie/tph.c
@@ -483,6 +483,68 @@ int pcie_tph_modes(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL(pcie_tph_modes);
 
+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;
+
+	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;
+	offset = PCI_TPH_BASE_SIZEOF;
+	num_entries = get_st_table_size(pdev);
+	for (i = 0; i < num_entries; i++) {
+		pci_write_config_word(pdev, pdev->tph_cap + offset,
+				      *st_entry++);
+		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;
+
+	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++);
+
+	/* Save all ST entries in extended capability structure */
+	st_entry = (u16 *)cap;
+	offset = PCI_TPH_BASE_SIZEOF;
+	num_entries = get_st_table_size(pdev);
+	for (i = 0; i < num_entries; i++) {
+		pci_read_config_word(pdev, pdev->tph_cap + offset,
+				     st_entry++);
+		offset += sizeof(u16);
+	}
+}
+
 void pci_tph_init(struct pci_dev *pdev)
 {
 	pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
-- 
2.45.1